CLYM

CLYM116 Phase 1 data in healthy volunteers to be presented at R&D Spotlight Event on September 3, 2026 Anticipate CLYM116 Phase 2 trial in IgA nephropathy to initiate dosing in Q3 2026 Budoprutug clinical programs continue to advance, with data expected from pMN, ITP, and SLE studies in Q4 2026 Financing extends cash runway into the second half of 2028 WELLESLEY HILLS, Mass., Aug. 06, 2026 (GLOBE NEWSWIRE) -- Climb Bio, Inc. (Nasdaq: CLYM), a clinical stage biotechnology company developing therapeutics for patients with immune-mediated diseases, today reported financial results for the second quarter ended June 30, 2026, and provided business updates. “2026 is proving to be a defining year for Climb Bio, and I am thrilled by the team’s execution,” said Aoife Brennan, M.B., Ch.B., President and Chief Executive Officer of Climb Bio. “We achieved important milestones for both budoprutug and CLYM116 over the past few months, and that momentum continues into the second half of the year with further data readouts across all four of our ongoing trials and the initiation of a Phase 2 trial of CLYM116 in IgAN patients. Currently at the forefront, I look forward to sharing initial Phase 1 data from CLYM116 in our September R&D Spotlight, where we will further highlight its potential as a best-in-class anti-APRIL antibody and provide additional details on our development strategy. With our continued progress across our pipeline, and supported by our strengthened balance sheet, we are well positioned to continue to execute on our strategic priorities and rapidly advance both programs toward pivotal development, setting the stage for what we believe will be an exciting 2027 for Climb.” CLYM116 Program Updates and Anticipated Milestones CLYM116 R&D Spotlight to be held on September 3, 2026. The Company will host a webcast to review the initial Phase 1 PK/PD data and development plans for CLYM116 for the treatment of IgA nephropathy (IgAN). Presented CLYM116 initial Phase 1 safety data and translational PK/PD modeling at the European Renal Association (ERA) Congress in June 2026. Clinical data demonstrated a favorable initial safety profile and supported continued development of CLYM116 for IgA nephropathy (IgAN). Anticipate additional Phase 1 data at a medical meeting in the fourth quarter of 2026. Mabworks Phase 1/2 study, enrollment ongoing. The Phase 1/2 trial being conducted by the Company's partner, Beijing Mabworks Biotech Co., Ltd., is ongoing, with dosing of IgAN patients in the Phase 2 portion expected to begin in the third quarter of 2026. Anticipate initial Phase 1 data at an upcoming medical meeting, and initial Phase 2 data in 2027. Budoprutug Program Updates and Anticipated Milestones PrisMN Phase 2 primary membranous nephropathy (pMN) trial, enrollment ongoing. PrisMN is a global open-label, dose-ranging Phase 2 study designed to evaluate pharmacodynamics (including B cells, anti-PLA2R, and total immunoglobulin) and preliminary efficacy (including complete and partial remission) in pMN patients with persistent proteinuria despite optimized renin-angiotensin-aldosterone system (RAAS) inhibition, and to identify a dose for Phase 3 clinical development. Enrollment is now ongoing in the second cohort (600 mg) and anticipate initial data, including preliminary B cell and anti-PLA2R data from low dose cohort (200mg at 12-24 weeks), at a medical meeting in the fourth quarter of 2026. Presented initial Phase 1b data in previously treated immune thrombocytopenia (ITP) patients at European Hematology Association Congress in June 2026. Initial safety data from the 250 mg and 500 mg cohorts demonstrated favorable safety and tolerability, and initial efficacy data from the 250 mg cohort demonstrated robust B-cell depletion, and encouraging platelet responses. These data support continued development of budoprutug across multiple autoimmune indications. Anticipate additional data from the 500 mg and 1000 mg cohorts in the fourth quarter of 2026. First patient dosed in China Phase 1b/2a trial of budoprutug in systemic lupus erythematosus (SLE); Global Phase 1b SLE trial enrollment ongoing. The global, open-label, dose-escalation Phase 1b trial of budoprutug in moderate to severe SLE is designed to evaluate safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and preliminary efficacy, including B-cell depletion, autoantibody levels, and clinical activity. The parallel China Phase 1b/2a trial in SLE is anticipated to provide complementary data and will also seek to enroll SLE patients with lupus nephritis. Data from these trials are expected to provide insights into budoprutug activity and will also help to inform future development efforts for the program broadly. Anticipate data, including safety and biomarker data from the Global study in the fourth quarter of 2026. Presented positive topline data for subcutaneous (SC) formulation of budoprutug at Company R&D Spotlight in May 2026. The SC formulation of budoprutug was generally safe and well-tolerated and resulted in robust B-cell depletion, which was similar to the IV formulation at a matched dose. The results support the advancement of the SC formulation to a multiple dose study in autoimmune disease patients to evaluate full B-cell depleting doses and optimal dosing regimen. Plan to initiate a multiple-dose study of the SC formulation in autoimmune patients; anticipate initial data in 2027. Corporate Updates On April 29, 2026, the Company completed a private placement financing, generating approximately $110 million in aggregated gross proceeds. The Company's financing supports the Company’s continued advancement of its clinical pipeline, including preparation for later-stage development, and extends its cash runway into the second half of 2028. In June 2026, the Company appointed Breanna O'Reilly, Ph.D., to its Board of Directors. Dr. O’Reilly, of RA Capital Management, brings deep scientific expertise and a valuable investor perspective to support the Company’s clinical development strategy and long-term growth objectives. Dr. O’Reilly fills the seat previously held by Dr. Andrew Levin, Advisor at RA Capital. Second Quarter Financial Results and Guidance Cash Position: Cash, cash equivalents, and marketable securities were $239.2 million as of June 30, 2026. Based on its current operating plan, the Company expects this balance to fund operations into the second half of 2028. Research and Development (R&D) Expenses: R&D expenses were $9.7 million for the three months ended June 30, 2026, compared to $6.6 million for the comparable period in 2025. General and Administrative (G&A) Expenses: G&A expenses were $5.6 million for the three months ended June 30, 2026, compared to $4.1 million for the comparable period in 2025. Other Income, Net: Other income, net was $1.9 million for the three months ended June 30, 2026, compared to $2.0 million for the comparable period in 2025. About Climb Bio, Inc.Climb Bio, Inc. is a clinical-stage biotechnology company with a mission to deliver high impact, disease-modifying medicines for individuals living with immune-mediated diseases, including those affecting kidney health. The Company’s pipeline includes, budoprutug, an anti-CD19 monoclonal antibody that has potential to treat a broad range of B-cell mediated diseases, and CLYM116, an anti-APRIL monoclonal antibody being developed for IgA nephropathy. For more information, please visit climbbio.com. About BudoprutugBudoprutug is a clinical-stage, anti-CD19 monoclonal antibody with the potential to address a broad range of B-cell mediated, immune-driven diseases. Designed with enhanced effector function and low picomolar affinity, budoprutug targets and depletes CD19-expressing B cells, including plasmablasts and certain plasma cells, key sources of pathogenic autoantibodies. Early clinical data suggest budoprutug may offer durable B-cell depletion, rapid reductions in autoantibodies, and clinical remission in primary membranous nephropathy (pMN). Budoprutug is being evaluated in clinical trials for pMN, immune thrombocytopenia (ITP), and systemic lupus erythematosus (SLE). A subcutaneous formulation is also in development to enable broader patient access. Budoprutug has been granted Orphan Drug Designation and Fast Track Designation by the FDA for the treatment of pMN. About CLYM116 CLYM116 is a clinical-stage monoclonal antibody targeting APRIL (A Proliferation-Inducing Ligand), a key driver of pathogenic B-cell activity in autoimmune diseases. CLYM116 employs a novel pH-dependent bind-and-release ‘sweeper’ mechanism to potently block APRIL signaling, promote lysosomal degradation of APRIL, and recycle the antibody to extend its half-life. This differentiated design offers the potential for rapid, deep, and durable inhibition of APRIL with a favorable safety profile and less frequent dosing. CLYM116 is being advanced for the treatment of IgA nephropathy (IgAN) and may also have broader utility across other B-cell mediated diseases where APRIL plays a critical role. Forward-Looking StatementsThis press release contains “forward-looking statements,” including without limitation statements regarding: future expectations, plans and prospects for Climb Bio; expectations regarding the therapeutic benefits, clinical potential and clinical development of CLYM116; the anticipated timelines for announcing data from Climb Bio’s ongoing and planned clinical trials; the anticipated timelines for enrolling patients in planned clinical trials; expectations regarding cash runway; Climb Bio’s expectations regarding the anticipated benefits of Climb Bio’s technology transfer and exclusive license agreement with Mabworks; and other statements containing the words “anticipate,” “believe,” “continue,” “could,” “expect,” “may,” “plan,” “potential,” should,” “suggest,” “target,” “will,” and similar expressions. Forward-looking statements are based on management’s current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in, or implied by, such forward-looking statements. Climb Bio may not actually achieve the plans, intentions or expectations disclosed in these forward-looking statements, and you should not place undue reliance on these forward-looking statements. These risks and uncertainties include, but are not limited to, important risks and uncertainties associated with: the ability of Climb Bio to timely and successfully achieve or recognize the anticipated benefits of its technology transfer and exclusive license agreement with Mabworks; Climb Bio’s ability to advance budoprutug and CLYM116 on the timelines expected or at all and to obtain and maintain necessary approvals from the U.S. Food and Drug Administration and other regulatory authorities; obtaining and maintaining the necessary approvals from investigational review boards at clinical trial sites and independent data safety monitoring boards; replicating in clinical trials positive results found in early-stage clinical trials or nonclinical studies; competing successfully with other companies that are seeking to develop treatments for primary membranous nephropathy, immune thrombocytopenia, systemic lupus erythematosus, IgA nephropathy and other immune-mediated diseases; maintaining or protecting intellectual property rights related to budoprutug, CLYM116 and/or its other product candidates; managing expenses; changes in applicable laws or regulation; the possibility that Climb Bio may be adversely affected by other economic, business and/or competitive factors; and raising the substantial additional capital needed, on the timeline necessary, to continue development of budoprutug, CLYM116 and any other product candidates Climb Bio may develop. For a discussion of other risks and uncertainties, and other important factors, any of which could cause Climb Bio’s actual results to differ materially from those contained in the forward-looking statements, see the “Risk Factors” section, as well as discussions of potential risks, uncertainties and other important factors, in Climb Bio’s most recent filings with the U.S. Securities and Exchange Commission. In addition, the forward-looking statements included in this press release represent Climb Bio’s views as of the date hereof and should not be relied upon as representing Climb Bio’s views as of any date subsequent to the date hereof. Climb Bio anticipates that subsequent events and developments will cause Climb Bio’s views to change. However, while Climb Bio may elect to update these forward-looking statements at some point in the future, Climb Bio specifically disclaims any obligation to do so, except as required by law. Investors and MediaCarlo Tanzi, Ph.D.Kendall Investor [email protected]

Company to share additional CLYM116 clinical data and plans for further development at R&D Spotlight in late summer Initiation of CLYM116 dosing in IgAN patients in Mabworks Phase 2 study expected in Q3 2026 WELLESLEY HILLS, Mass., June 05, 2026 (GLOBE NEWSWIRE) -- Climb Bio, Inc. (Nasdaq: CLYM), a clinical stage biotechnology company developing therapeutics for patients with immune-mediated diseases, today announced translational pharmacometric modeling and initial Phase 1 safety data for CLYM116, its anti-APRIL monoclonal antibody. Clinical data demonstrated a favorable initial safety profile, supporting continued development of CLYM116 in IgA nephropathy (IgAN). These data will be presented today as an oral session at the European Renal Association (ERA) Congress 2026, which is being held June 3-6, 2026, in Glasgow, Scotland. The Company also announced that it plans to share initial pharmacokinetic and pharmacodynamic (PK/PD) data, as well as updated safety data from the ongoing Phase 1 studies of CLYM116 in healthy volunteers, at the next installment of its R&D Spotlight Series, expected to take place in late summer. Based on the interim data from ongoing Phase 1 studies in healthy volunteers, CLYM116 has been generally well tolerated with no unexpected safety findings. These clinical data include results from a Phase 1 study being conducted by Climb Bio in Australia, and a parallel ongoing Phase 1 study being conducted by the Company’s partner, Beijing Mabworks Biotech (Mabworks), in China. With the safety profile observed to date and supportive preclinical data, the Company plans to continue to advance CLYM116 into further clinical development, and Mabworks expects to initiate dosing in IgAN patients in the Phase 2 portion of its ongoing study in the third quarter of 2026. Climb Bio maintains global rights to CLYM116 outside of Greater China. “We are encouraged by the safety profile observed to date with CLYM116 in healthy volunteers at doses up to 320 mg,” said Edgar Charles, M.D., Chief Medical Officer of Climb Bio. “Together with the translational and pharmacometric modeling results, these data support our belief that CLYM116 could potentially offer a differentiated approach in IgAN, with the potential for substantial IgA reduction and less frequent dosing. We are excited to continue to advance CLYM116 development and for Mabworks to begin enrolling IgAN patients. We look forward to providing additional program updates, including initial PK/PD and updated safety data in healthy volunteers and further details on our development strategy, at our upcoming R&D Spotlight event.” Key highlights from the presentation: A translational PK/PD model derived from pooled non-human primate (NHP) data projected healthy human exposure and dose-dependent IgA suppression for CLYM116, suggesting the potential for less-frequent dosing than first generation anti-APRIL approaches. Literature analysis shows strong correlation in IgA reduction between NHP and healthy volunteer studies. Global Phase 1 strategy, incorporating parallel healthy volunteer datasets ex-China and China (n≈80, doses 25 mg to 640 mg), expected to support a robust population PK foundation to inform dose selection. CLYM116 has been generally well tolerated based on preliminary safety data from healthy volunteers receiving single doses up to 320 mg or placebo (n=49), with no unexpected safety findings reported to date. Following the Focused Oral session at 15:03 p.m. BST, the presentation will be available on the Pipeline & Science—Publications page of the Company’s website here. About Climb Bio, Inc.Climb Bio, Inc. is a clinical-stage biotechnology company with a mission to deliver high impact, disease-modifying medicines for individuals living with immune-mediated diseases, including those affecting kidney health. The Company’s pipeline includes, budoprutug, an anti-CD19 monoclonal antibody that has potential to treat a broad range of B-cell mediated diseases, and CLYM116, an anti-APRIL monoclonal antibody being developed for IgA nephropathy. For more information, please visit climbbio.com. About CLYM116 CLYM116 is a clinical-stage monoclonal antibody targeting APRIL (A Proliferation-Inducing Ligand), a key driver of pathogenic B-cell activity in autoimmune diseases. CLYM116 employs a novel pH-dependent bind-and-release ‘sweeper’ mechanism to potently block APRIL signaling, promote lysosomal degradation of APRIL, and recycle the antibody to extend its half-life. This differentiated design offers the potential for rapid, deep, and durable inhibition of APRIL with a favorable safety profile and less frequent dosing. CLYM116 is being advanced for the treatment of IgA nephropathy (IgAN) and may also have broader utility across other B-cell mediated diseases where APRIL plays a critical role. Forward-Looking StatementsThis press release contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, including without limitation statements regarding: future expectations, plans and prospects for Climb Bio; expectations regarding the therapeutic benefits, clinical potential and clinical development of CLYM116; the anticipated timelines for announcing data from Climb Bio’s ongoing and planned clinical trials; the anticipated timelines for enrolling patients in planned clinical trials; Climb Bio’s expectations regarding the translation of results observed in preclinical animal model models to humans; the anticipated benefits of Climb Bio’s technology transfer and exclusive license agreement with Mabworks; and other statements containing the words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “should,” “suggest,” “target,” “would,” “will,” “working” and similar expressions. Forward-looking statements are based on management’s current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in, or implied by, such forward-looking statements. Climb Bio may not actually achieve the plans, intentions or expectations disclosed in these forward-looking statements, and you should not place undue reliance on these forward-looking statements. These risks and uncertainties include, but are not limited to, important risks and uncertainties associated with: the ability of Climb Bio to timely and successfully achieve or recognize the anticipated benefits of its acquisition of Tenet Medicines, Inc. and its technology transfer and exclusive license agreement with Mabworks; Climb Bio’s ability to advance budoprutug and CLYM116 on the timelines expected or at all and to obtain and maintain necessary approvals from the U.S. Food and Drug Administration and other regulatory authorities; obtaining and maintaining the necessary approvals from investigational review boards at clinical trial sites and independent data safety monitoring boards; replicating in clinical trials positive results found in early-stage clinical trials or nonclinical studies; competing successfully with other companies that are seeking to develop treatments for primary membranous nephropathy, immune thrombocytopenia, systemic lupus erythematosus, IgA nephropathy and other immune-mediated diseases; maintaining or protecting intellectual property rights related to budoprutug, CLYM116 and/or its other product candidates; managing expenses; changes in applicable laws or regulation; the possibility that Climb Bio may be adversely affected by other economic, business and/or competitive factors; and raising the substantial additional capital needed, on the timeline necessary, to continue development of budoprutug, CLYM116 and any other product candidates Climb Bio may develop. For a discussion of other risks and uncertainties, and other important factors, any of which could cause Climb Bio’s actual results to differ materially from those contained in the forward-looking statements, see the “Risk Factors” section, as well as discussions of potential risks, uncertainties and other important factors, in Climb Bio’s most recent filings with the U.S. Securities and Exchange Commission. In addition, the forward-looking statements included in this press release represent Climb Bio’s views as of the date hereof and should not be relied upon as representing Climb Bio’s views as of any date subsequent to the date hereof. Climb Bio anticipates that subsequent events and developments will cause Climb Bio’s views to change. However, while Climb Bio may elect to update these forward-looking statements at some point in the future, Climb Bio specifically disclaims any obligation to do so, except as required by law. Investors and MediaCarlo Tanzi, Ph.D.Kendall Investor [email protected]

Robust B-cell depletion observed with budoprutug subcutaneous formulation in healthy volunteers, supporting continued development CLYM116 modeling and initial Phase 1 safety data to be presented at ERA 2026 with initial Phase 1 PK/PD data expected mid-2026 Budoprutug pMN, ITP, and SLE clinical trials enrolling to plan; anticipate data from all ongoing trials in 2026 Secured $110 million private placement led by top-tier healthcare investors WELLESLEY HILLS, Mass., May 07, 2026 (GLOBE NEWSWIRE) -- Climb Bio, Inc. (Nasdaq: CLYM), a clinical-stage biotechnology company developing therapeutics for patients with immune-mediated diseases, today reported financial results for the first quarter ended March 31, 2026, and provided business updates. “During the first quarter, we continued to execute on a focused development strategy aimed at generating clear clinical and translational data across our two programs,” said Aoife Brennan, M.B., Ch.B., President and Chief Executive Officer of Climb Bio. “For budoprutug, our anti-CD19 monoclonal antibody, we recently hosted an R&D Spotlight highlighting our clinical progress, including topline data from the subcutaneous formulation and the broader potential opportunity for CD19 targeting in autoimmune disease. With multiple studies underway, we believe we are well positioned to assess the potential of budoprutug across several indications with significant unmet need. In parallel, we continue to advance CLYM116, our anti-APRIL monoclonal antibody, and look forward to sharing additional data on this program in the coming months. As we move through 2026, we remain focused on disciplined execution and building a robust data foundation to inform the long-term potential of both programs.” Budoprutug Program Updates and Anticipated Milestones Budoprutug CD19 R&D Spotlight held May 5, 2026. The Company held a webcast to review the development strategy and program updates for budoprutug, the potential opportunity presented by targeting CD19, and anticipated upcoming data readouts. Presented data from Phase 1 trial of subcutaneous (SC) formulation in healthy volunteers. At the recent R&D Spotlight the Company shared data from the completed Phase 1 trial of budoprutug’s SC formulation. Data demonstrated robust B-cell depletion that was similar between SC and intravenous (IV) administration at matched doses. These results, together with a favorable pharmacodynamic and tolerability profile, support advancement into an autoimmune patient study to evaluate full B-cell depleting doses and optimal dosing regimen. Plan to initiate a multiple-dose study of the SC formulation in autoimmune patients. PrisMN Phase 2 primary membranous nephropathy (pMN) trial, enrollment ongoing; Fast Track Designation (FTD) granted by FDA. PrisMN is a global open-label, dose-ranging Phase 2 study designed to evaluate pharmacodynamics (including B cells, anti-PLA2R (Phospholipase A2 Receptor), and total immunoglobulin) and preliminary efficacy (including complete and partial remission) in pMN patients with persistent proteinuria despite optimized renin-angiotensin-aldosterone system (RAAS) inhibition, and to identify a dose for Phase 3 clinical development. In April, the U.S. Food & Drug Administration (FDA) granted FTD to budoprutug for the treatment of pMN. Anticipate initial data, including preliminary B cell and anti-PLA2R data from low dose cohort (200mg at 12-24 weeks), in Q4 2026. Phase 1b/2a immune thrombocytopenia (ITP) trial, enrollment ongoing. This global open-label, dose-escalation Phase 1b/2a trial of budoprutug in previously treated patients with ITP is designed to evaluate safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and preliminary efficacy, including B-cell depletion and platelet counts. Data from this trial are expected to provide a deeper understanding of budoprutug activity and dosing and will help inform future development. Anticipate initial data, including initial B-cell depletion and platelet data from the low dose cohort (250mg at 24 weeks), in June 2026 Global Phase 1b systemic lupus erythematosus (SLE) trial, enrollment ongoing; China Phase 1b/2a SLE trial, in study start-up. The global, open-label, dose-escalation Phase 1b trial of budoprutug in moderate to severe SLE is designed to evaluate safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary efficacy, including B-cell depletion, autoantibody levels, and clinical activity. The parallel China Phase 1b/2a trial in SLE is anticipated to provide complementary data and will also seek to enroll SLE patients with lupus nephritis. Data from these trials are expected to provide insights into budoprutug activity and will also help to inform future development efforts for our program broadly. Anticipate initial B cell data from the Global study, in Q4 2026 and anticipate first patient dosed in China SLE study in Q2 2026. CLYM116 Program Updates and Anticipated Milestones Climb Bio to present modeling data for CLYM116 at the upcoming European Renal Association Congress in June. These data will include PK and PD modeling from nonhuman primates to humans, as well as initial safety data from the ongoing Phase 1 study in healthy volunteers. Phase 1 healthy volunteer study, enrollment ongoing. This Phase 1 trial in healthy volunteers is evaluating safety, pharmacokinetics, and pharmacodynamics of CLYM116. Separately, the Company’s partner, Beijing Mabworks Biotech Co., Ltd. (NEEQ Code: 874070, Mabworks), continues to enroll its Phase 1/2 study consisting of a single ascending dose study in healthy volunteers, followed by a multiple ascending dose study in IgAN patients. Anticipate initial PK/PD data from Phase 1 healthy volunteer study in mid-2026. Corporate Updates On April 29, 2026, the Company completed a private placement financing, generating approximately $110 million in gross proceeds, further strengthening the balance sheet ahead of multiple anticipated data readouts. Fourth Quarter and Full Year 2025 Financial Results and Guidance Cash Position: Cash, cash equivalents, and marketable securities were $146.3 million as of March 31, 2026. Based on its current operating plan, the Company expects this balance to fund operations into 2028, excluding the gross proceeds received from the April 2026 private placement. The Company is currently evaluating the impact of the recently completed financing on its operating plan and expects to provide updated cash runway guidance at a later date. Research and Development (R&D) expenses: R&D expenses were $9.4 million for the three months ended March 31, 2026, compared to $17.3 million for the comparable period in 2025, including the $9 million upfront payment to Beijing Mabworks Biotech Co., Ltd. as part of the license agreement for CLYM116. General and Administrative (G&A) expenses: G&A expenses were $5.8 million for the three months ended March 31, 2026, compared to $6.0 million for the comparable period in 2025. Other income, net: Other income, net was $1.5 million for the three months ended March 31, 2026, compared to $2.2 million for the comparable period in 2025. About Climb Bio, Inc. Climb Bio, Inc. is a clinical-stage biotechnology company with a mission to deliver high impact, disease-modifying medicines for individuals living with immune-mediated diseases, including those affecting kidney health. The Company’s pipeline includes, budoprutug, an anti-CD19 monoclonal antibody that has potential to treat a broad range of B-cell mediated diseases, and CLYM116, an anti-APRIL monoclonal antibody being developed for IgA nephropathy. For more information, please visit climbbio.com. About Budoprutug Budoprutug is a clinical-stage, anti-CD19 monoclonal antibody with the potential to address a broad range of B-cell mediated, immune-driven diseases. Designed with enhanced effector function and low picomolar affinity, budoprutug targets and depletes CD19-expressing B cells, including plasmablasts and certain plasma cells, key sources of pathogenic autoantibodies. Early clinical data suggest budoprutug may offer durable B-cell depletion, rapid reductions in autoantibodies, and clinical remission in primary membranous nephropathy (pMN). Budoprutug is being evaluated in clinical trials for pMN, immune thrombocytopenia (ITP), and systemic lupus erythematosus (SLE). A subcutaneous formulation is also in development to enable broader patient access. Budoprutug has been granted Orphan Drug Designation and Fast Track Designation by the FDA for the treatment of pMN. About CLYM116 CLYM116 is a clinical-stage monoclonal antibody targeting APRIL (A Proliferation-Inducing Ligand), a key driver of pathogenic B-cell activity in autoimmune diseases. CLYM116 employs a novel pH-dependent bind-and-release ‘sweeper’ mechanism to potently block APRIL signaling, promote lysosomal degradation of APRIL, and recycle the antibody to extend its half-life. This differentiated design offers the potential for rapid, deep, and durable inhibition of APRIL with a favorable safety profile and less frequent dosing. CLYM116 is being advanced for the treatment of IgA nephropathy (IgAN) and may also have broader utility across other B-cell mediated diseases where APRIL plays a critical role. Forward-Looking Statements This press release contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, including without limitation statements regarding: future expectations, plans and prospects for Climb Bio; expectations regarding the therapeutic benefits, clinical potential and clinical development of budoprutug and CLYM116; the anticipated timelines for initiating Climb Bio’s Phase 1b/2a clinical trial of budoprutug in systemic lupus erythematosus in China; the anticipated timelines for announcing data from Climb Bio’s ongoing and planned clinical trials and Beijing Mabworks Biotech Co., Ltd.’s (“Mabworks”) Phase 1/2 trial of CLYM116; the anticipated benefits of Climb Bio’s technology transfer and exclusive license agreement with Mabworks; the sufficiency of Climb Bio’s cash resources for the period anticipated; the impact of the proceeds from the April 2026 private placement on Climb Bio’s balance sheet; and other statements containing the words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “would,” “will,” “working” and similar expressions. Forward-looking statements are based on management’s current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in, or implied by, such forward-looking statements. Climb Bio may not actually achieve the plans, intentions or expectations disclosed in these forward-looking statements, and you should not place undue reliance on these forward-looking statements. These risks and uncertainties include, but are not limited to, important risks and uncertainties associated with: the ability of Climb Bio to timely and successfully achieve or recognize the anticipated benefits of its acquisition of Tenet Medicines, Inc. and its technology transfer and exclusive license agreement with Mabworks; Climb Bio’s ability to advance budoprutug and CLYM116 on the timelines expected or at all and to obtain and maintain necessary approvals from the U.S. Food and Drug Administration and other regulatory authorities; obtaining and maintaining the necessary approvals from investigational review boards at clinical trial sites and independent data safety monitoring boards; replicating in clinical trials positive results found in early-stage clinical trials or nonclinical studies; competing successfully with other companies that are seeking to develop treatments for primary membranous nephropathy, immune thrombocytopenia, systemic lupus erythematosus, IgA nephropathy and other immune-mediated diseases; maintaining or protecting intellectual property rights related to budoprutug, CLYM116 and/or its other product candidates; the outcome of any legal proceedings or other disputes; managing expenses; changes in applicable laws or regulation; the possibility that Climb Bio may be adversely affected by other economic, business and/or competitive factors; and raising the substantial additional capital needed, on the timeline necessary, to continue development of budoprutug, CLYM116 and any other product candidates Climb Bio may develop. For a discussion of other risks and uncertainties, and other important factors, any of which could cause Climb Bio’s actual results to differ materially from those contained in the forward-looking statements, see the “Risk Factors” section, as well as discussions of potential risks, uncertainties and other important factors, in Climb Bio’s most recent filings with the U.S. Securities and Exchange Commission. In addition, the forward-looking statements included in this press release represent Climb Bio’s views as of the date hereof and should not be relied upon as representing Climb Bio’s views as of any date subsequent to the date hereof. Climb Bio anticipates that subsequent events and developments will cause Climb Bio’s views to change. However, while Climb Bio may elect to update these forward-looking statements at some point in the future, Climb Bio specifically disclaims any obligation to do so, except as required by law. Investors and Media Carlo Tanzi, Ph.D. Kendall Investor Relations [email protected]

Dosing completed in Phase 1 study of budoprutug subcutaneous formulation, with data expected in H1 2026 Budoprutug clinical trials ongoing in pMN, ITP, and SLE, with initial data from all three trials expected in H2 2026 Enrollment ongoing in CLYM116 Phase 1 healthy volunteer study, with initial data expected mid-2026 Strong financial position with cash runway expected into 2028 WELLESLEY HILLS, Mass., March 05, 2026 (GLOBE NEWSWIRE) -- Climb Bio, Inc. (Nasdaq: CLYM), a clinical-stage biotechnology company developing therapeutics for patients with immune-mediated diseases, today reported financial results for the fourth quarter and full year ended December 31, 2025, and provided business updates. “Throughout 2025, we translated strategy into disciplined execution and meaningfully advanced our pipeline,” said Aoife Brennan, M.B., Ch.B., President and Chief Executive Officer of Climb Bio. “With three clinical trials underway for budoprutug, our anti-CD19 monoclonal antibody, we are in a strong position to evaluate the program across multiple indications with high unmet need. We recently completed dosing in a fourth trial evaluating a subcutaneous formulation of budoprutug and are on track to share data from this study in the first half of 2026. In parallel, we continue to advance the clinical development of CLYM116, our anti-APRIL monoclonal antibody, which we believe has the potential to deliver a differentiated clinical profile in IgAN, and could represent a substantial therapeutic and commercial opportunity. With a global clinical footprint and multiple expected data readouts in 2026, we enter the year positioned for continued execution and an exciting, data-rich period ahead.” Budoprutug Program Updates and Anticipated Milestones PrisMN Phase 2 primary membranous nephropathy (pMN) trial, enrollment ongoing. PrisMN is a global open-label, dose-ranging Phase 2 study designed to evaluate pharmacodynamics (including B cells, anti-PLA2R, and total immunoglobulin) and preliminary efficacy (including complete and partial remission) in pMN patients with persistent proteinuria despite optimized renin-angiotensin-aldosterone system (RAAS) inhibition, and to identify a dose for Phase 3 clinical development. In November 2025, we published long-term outcome data from the Phase 1b trial of budoprutug in pMN at the 2025 American Society of Nephrology (ASN) Kidney Week that demonstrated long-term control of proteinuria. Anticipate initial data, including preliminary B cell and anti-PLA2R data, in H2 2026. Phase 1b/2a immune thrombocytopenia (ITP) trial, enrollment ongoing. This global open-label, dose-escalation Phase 1b/2a trial of budoprutug in previously treated patients with ITP is designed to evaluate safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary efficacy, including B-cell depletion and platelet counts. Data from this trial are expected to provide a deeper understanding of budoprutug activity and dosing and will help inform future development. At the 2025 American Society of Hematology (ASH) conference, we detailed the Phase 1b/2a trial design. Anticipate initial data, including preliminary efficacy, in H2 2026. Global Phase 1b systemic lupus erythematosus (SLE) trial, enrollment ongoing; China Phase 1b/2a SLE trial, in study start-up. The global, open-label, dose-escalation Phase 1b trial of budoprutug in moderate to severe SLE is designed to evaluate safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary efficacy, including B-cell depletion, autoantibody levels, and clinical activity. Data from this trial are expected to provide insights into budoprutug activity and will also help to inform future development efforts for our program broadly. In December 2025, we received Investigational New Drug (IND) clearance in China to initiate a separate, parallel Phase 1b trial in SLE, anticipated to provide complementary data, and will also seek to enroll SLE patients with lupus nephritis. Anticipate initial data from the Global study, including preliminary efficacy, in H2 2026 and anticipate first patient dosed in China SLE study in H1 2026. Phase 1 trial of subcutaneous formulation, dosing completed. Dosing in the Phase 1 trial in healthy volunteers has been completed. The study is designed to evaluate bioavailability, pharmacokinetics, and pharmacodynamics, including B-cell depletion, of the subcutaneous formulation of budoprutug. Anticipate data in H1 2026. CLYM116 Program Updates and Anticipated Milestones Phase 1 healthy volunteer study, enrollment ongoing. This Phase 1 trial in healthy volunteers will evaluate safety, pharmacokinetics, and pharmacodynamics of CLYM116. Separately, our partner, Beijing Mabworks Biotech Co., Ltd. (NEEQ Code: 874070, Mabworks), has initiated a Phase 1/2 study consisting of a single ascending dose study in healthy volunteers, followed by a multiple ascending dose study in IgAN patients. In November, we presented a poster highlighting additional data on the favorable CLYM116 preclinical pharmacokinetic and pharmacodynamic profile at 2025 ASN Kidney Week. Anticipate initial healthy volunteer data in mid-2026. Fourth Quarter and Full Year 2025 Financial Results and Guidance Cash Position: Cash, cash equivalents, and marketable securities were $160.7 million as of December 31, 2025, expected to fund operations into 2028. Research and Development (R&D) expenses: R&D expenses were $13.7 million for the three months ended December 31, 2025, compared to $6.0 million for the comparable period in 2024, and were $46.7 million for the full year 2025, compared to $14.3 million for the full year 2024. General and Administrative (G&A) expenses: G&A expenses were $5.6 million for the three months ended December 31, 2025, compared to $5.0 million for the comparable period in 2024, and were $21.2 million for the full year 2025, compared to $16.0 million for the full year 2024. Other income, net: Other income, net was $1.8 million for the three months ended December 31, 2025, compared to $2.5 million for the comparable period in 2024, and was $8.0 million for the full year 2025, compared to $8.1 million for the full year 2024. About Climb Bio, Inc. Climb Bio, Inc. is a clinical-stage biotechnology company with a mission to deliver high impact, disease-modifying medicines for individuals living with immune-mediated diseases, including those affecting kidney health. The Company’s pipeline includes, budoprutug, an anti-CD19 monoclonal antibody that has potential to treat a broad range of B-cell mediated diseases, and CLYM116, an anti-APRIL monoclonal antibody being developed for IgA nephropathy. For more information, please visit climbbio.com. About Budoprutug Budoprutug is a clinical-stage, anti-CD19 monoclonal antibody with the potential to address a broad range of B-cell mediated, immune-driven diseases. Designed with enhanced effector function and low picomolar affinity, budoprutug targets and depletes CD19-expressing B cells, including plasmablasts and certain plasma cells, key sources of pathogenic autoantibodies. Early clinical data suggest budoprutug may offer durable B-cell depletion, rapid reductions in autoantibodies, and clinical remission in primary membranous nephropathy (pMN). Budoprutug is being evaluated in clinical trials for pMN, immune thrombocytopenia (ITP), and systemic lupus erythematosus (SLE). A subcutaneous formulation is also in development to enable broader patient access. Budoprutug has been granted orphan drug designation by the FDA for the treatment of pMN. About CLYM116 CLYM116 is a clinical-stage monoclonal antibody targeting APRIL (A Proliferation-Inducing Ligand), a key driver of pathogenic B-cell activity in autoimmune diseases. CLYM116 employs a novel pH-dependent bind-and-release ‘sweeper’ mechanism to potently block APRIL signaling, promote lysosomal degradation of APRIL, and recycle the antibody to extend its half-life. This differentiated design offers the potential for rapid, deep, and durable inhibition of APRIL with a favorable safety profile and less frequent dosing. CLYM116 is being advanced for the treatment of IgA nephropathy (IgAN) and may also have broader utility across other B-cell mediated diseases where APRIL plays a critical role. Forward-Looking Statements This press release contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, including without limitation statements regarding: future expectations, plans and prospects for Climb Bio; expectations regarding the therapeutic benefits, clinical potential and clinical development of budoprutug and CLYM116; the anticipated timelines for initiating Climb Bio’s parallel Phase 1b clinical trial of budoprutug in China; the anticipated timelines for announcing data from Climb Bio’s ongoing and planned clinical trials and Beijing Mabworks Biotech Co., Ltd.’s (“Mabworks”) Phase 1/2 trial of CLYM116; the anticipated benefits of Climb Bio’s technology transfer and exclusive license agreement with Mabworks; the sufficiency of Climb Bio’s cash resources for the period anticipated; and other statements containing the words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “would,” “will,” “working” and similar expressions. Forward-looking statements are based on management’s current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in, or implied by, such forward-looking statements. Climb Bio may not actually achieve the plans, intentions or expectations disclosed in these forward-looking statements, and you should not place undue reliance on these forward-looking statements. These risks and uncertainties include, but are not limited to, important risks and uncertainties associated with: the ability of Climb Bio to timely and successfully achieve or recognize the anticipated benefits of its acquisition of Tenet Medicines, Inc. and its technology transfer and exclusive license agreement with Mabworks; Climb Bio’s ability to advance budoprutug and CLYM116 on the timelines expected or at all and to obtain and maintain necessary approvals from the U.S. Food and Drug Administration and other regulatory authorities; obtaining and maintaining the necessary approvals from investigational review boards at clinical trial sites and independent data safety monitoring boards; replicating in clinical trials positive results found in early-stage clinical trials or nonclinical studies; competing successfully with other companies that are seeking to develop treatments for primary membranous nephropathy, immune thrombocytopenia, systemic lupus erythematosus, IgA nephropathy and other immune-mediated diseases; maintaining or protecting intellectual property rights related to budoprutug, CLYM116 and/or its other product candidates; managing expenses; changes in applicable laws or regulation; the possibility that Climb Bio may be adversely affected by other economic, business and/or competitive factors; and raising the substantial additional capital needed, on the timeline necessary, to continue development of budoprutug, CLYM116 and any other product candidates Climb Bio may develop. For a discussion of other risks and uncertainties, and other important factors, any of which could cause Climb Bio’s actual results to differ materially from those contained in the forward-looking statements, see the “Risk Factors” section, as well as discussions of potential risks, uncertainties and other important factors, in Climb Bio’s most recent filings with the U.S. Securities and Exchange Commission. In addition, the forward-looking statements included in this press release represent Climb Bio’s views as of the date hereof and should not be relied upon as representing Climb Bio’s views as of any date subsequent to the date hereof. Climb Bio anticipates that subsequent events and developments will cause Climb Bio’s views to change. However, while Climb Bio may elect to update these forward-looking statements at some point in the future, Climb Bio specifically disclaims any obligation to do so, except as required by law. Investors and Media Carlo Tanzi, Ph.D. Kendall Investor Relations [email protected]

PrisMN Phase 2 trial of budoprutug in Primary Membranous Nephropathy (pMN) initiated Phase 1 trial of budoprutug subcutaneous formulation initiated, with initial data expected in H1 2026 Clinical trials of budoprutug in Immune Thrombocytopenia (ITP) and Systemic Lupus Erythematosus (SLE) ongoing, with initial data from both trials expected in H2 2026 Regulatory clearance obtained to initiate CLYM116 Phase 1 trial; anticipate dosing first subject by year-end, with initial data expected mid-2026 Leadership team strengthened with the appointments of Susan Altschuller, Ph.D., MBA, Chief Financial Officer, Adam Villa SVP, Technical Operations, and Ashley Jones SVP, People & Workforce Strategy Cash runway expected through 2027, anticipated to fund company through multiple upcoming clinical milestones WELLESLEY HILLS, Mass., Nov. 06, 2025 (GLOBE NEWSWIRE) -- Climb Bio, Inc. (Nasdaq: CLYM), a clinical-stage biotechnology company developing therapeutics for patients with immune-mediated diseases, today reported financial results for the third quarter ended September 30, 2025, and provided business updates. “We are proud to have executed effectively against our 2025 plan, advancing the development of budoprutug and CLYM116 while continuing to build organizational strength and capabilities,” said Aoife Brennan, M.B., Ch.B., President and Chief Executive Officer of Climb Bio. “Both of our programs, budoprutug, an anti-CD19 antibody in clinical development for multiple B-cell mediated diseases, and CLYM116, an anti-APRIL antibody being advanced for IgA nephropathy, have the potential to deliver differentiated clinical profiles and unlock meaningful therapeutic and commercial opportunities in immune-mediated diseases. Looking ahead, we expect 2026 to be an exciting and data-rich year for Climb Bio, with datasets from both programs that will help guide our ascent and the next phase of development.” Budoprutug Program Updates and Anticipated Milestones Phase 2 primary membranous nephropathy (pMN) trial, known as ‘PrisMN,’ initiated in multiple countries, with dosing expected to initiate in the coming weeks. PrisMN, an open-label, dose-ranging Phase 2 clinical trial, is designed to further evaluate safety, pharmacokinetics, pharmacodynamics (including B cells, anti-PLA2R, total immunoglobulin), and preliminary efficacy, including complete and partial remission, and identify a dose to carry forward into Phase 3. Climb Bio recently published an abstract as part of the upcoming 2025 American Society of Nephrology (ASN) Kidney Week on the long-term follow-up clinical data from the previously conducted Phase 1b trial. Phase 1 trial of subcutaneous (SC) formulation FPI achieved, enrollment ongoing. Climb Bio is now enrolling healthy volunteers in a Phase 1 trial to evaluate bioavailability, pharmacokinetics, and pharmacodynamics. Expect initial Phase 1 SC data in H1 2026. Phase 1b/2a immune thrombocytopenia (ITP) enrollment ongoing. Climb Bio is enrolling an open-label, dose-escalation Phase 1b/2a clinical trial in patients with ITP to evaluate safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary efficacy, including B cell depletion and platelet counts. Data from this trial is expected to provide a deeper understanding of budoprutug activity and dosing and will help inform future development in ITP and other immune-mediated diseases. Anticipate initial ITP data, including preliminary efficacy, in H2 2026. Phase 1b systemic lupus erythematosus (SLE) enrollment ongoing. Climb Bio is enrolling an open-label, dose-escalation Phase 1b clinical trial in patients with SLE to evaluate safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary efficacy, including B-cell depletion, autoantibody levels, and clinical activity. Data from this trial is expected to provide insights into budoprutug activity after a single intravenous dose and will also help to inform future development efforts for the program broadly. Anticipate initial SLE data, including preliminary efficacy, in H2 2026. CLYM116 Program Updates and Anticipated Milestones CLYM116, an antibody targeting the APRIL pathway for IgA nephropathy (IgAN), advancing toward clinical development. Climb Bio held an R&D Spotlight Webcast on September 29, 2025 to review the IgAN development opportunity and preclinical data demonstrating the differentiation of CLYM116 from a first-generation anti-APRIL monoclonal antibody. The Company will be presenting a poster highlighting further data on the favorable CLYM116 preclinical pharmacokinetic and pharmacodynamic profile at the upcoming 2025 ASN Kidney Week, which is being held in Houston, TX, on November 6-9, 2025. In October 2025, the Company obtained regulatory clearance of a Clinical Trial Application to initiate a Phase 1 trial of CLYM116 in healthy volunteers. Expect to dose the first subject by year-end 2025, with initial data anticipated mid-2026. Corporate Updates Appointed New Members of Leadership Team, including Susan Altschuller, Ph.D., MBA as Chief Financial Officer, Adam Villa as SVP, Technical Operations, and Ashley Jones as SVP, People & Workforce Strategy Susan Altschuller brings over two decades of strategic and financial leadership experience and previously served as the Chief Financial Officer of Cerevel Therapeutics until its acquisition by AbbVie and ImmunoGen, supporting the company’s first commercial launch. Dr. Altschuller holds a BSE in Biomedical Engineering with honors from Tulane University, a Ph.D. in Biomedical Engineering from the Illinois Institute of Technology, and an MBA from the MIT Sloan School of Management. Adam Villa is an accomplished executive with experience spanning technical development, chemistry, manufacturing, and controls (CMC) strategy, and global supply management. He most recently served as Vice President, CMC at Generation Bio and previously held leadership roles at CRISPR Therapeutics and Biogen. Adam received an MBA from MIT Sloan School of Management and a Master of Science degree in Chemical Engineering from MIT School of Engineering. He earned a BE in Chemical Engineering and an AB in Engineering Sciences from Dartmouth College. Ashley Jones is a seasoned people and culture leader with nearly 20 years of experience supporting executive teams and building organizations in the biotechnology sector. She previously founded and led Cultivate Co., a consulting practice providing human resources support and led people and operations functions at Ananke Therapeutics, Imara, and SQZ Biotechnologies. Ashley holds a Graduate Certificate in Human Resources Management from Northeastern University and a BA in English and Psychology from Ohio Wesleyan University. Third Quarter 2025 Financial Results Cash Position: Cash, cash equivalents and marketable securities were $175.8 million as of September 30, 2025. Cash, cash equivalents and marketable securities are expected to fund operations through 2027. Research and Development (R&D) expenses: R&D expenses were $9.1 million for the three months ended September 30, 2025, compared to $6.2 million for the comparable period in 2024. General and Administrative (G&A) expenses: G&A expenses were $5.8 million for the three months ended September 30, 2025, compared to $5.5 million for the comparable period in 2024. Other income, net: Other income, net was $2.0 million for the three months ended September 30, 2025, compared to $2.8 million for the comparable period in 2024. About Climb Bio, Inc. Climb Bio, Inc. is a clinical-stage biotechnology company developing therapeutics for patients with immune-mediated diseases. The Company’s pipeline includes, budoprutug, an anti-CD19 monoclonal antibody that has demonstrated B-cell depletion and has potential to treat a broad range of B-cell mediated diseases, and CLYM116, an anti-APRIL monoclonal antibody being developed for IgA nephropathy. For more information, please visit climbbio.com. About Budoprutug Budoprutug is a clinical-stage, anti-CD19 monoclonal antibody being developed by Climb Bio to address a broad range of B-cell mediated, immune-driven diseases. Designed with enhanced effector function and low picomolar affinity, budoprutug targets and depletes CD19-expressing B cells, including plasma blasts that are key sources of pathogenic autoantibodies. Climb Bio is evaluating budoprutug in multiple clinical trials across three lead indications—primary membranous nephropathy (pMN), immune thrombocytopenia (ITP), and systemic lupus erythematosus (SLE)—which represent distinct mechanistic subtypes of immune-mediated disease. Early clinical data suggest budoprutug may offer durable B-cell depletion, rapid reductions in autoantibodies, and clinical remission in pMN. A subcutaneous formulation is also in development to enable broader patient access and potential home-based dosing. Budoprutug has been granted orphan drug designation by the FDA for the treatment of pMN. About CLYM116 CLYM116 is a clinical-stage monoclonal antibody targeting APRIL (A Proliferation-Inducing Ligand), a key driver of pathogenic B-cell activity in autoimmune diseases. CLYM116 employs a novel pH-dependent bind-and-release mechanism to potently block APRIL signaling, promote lysosomal degradation of APRIL, and recycle the antibody to extend its half-life. This differentiated design offers the potential for rapid, deep, and durable inhibition of APRIL with a favorable safety profile and less frequent dosing. CLYM116 is being advanced for the treatment of IgA nephropathy (IgAN) and may also have broader utility across other B-cell mediated diseases where APRIL plays a critical role. Forward-Looking Statements This press release contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, including without limitation statements regarding: future expectations, plans and prospects for Climb Bio; expectations regarding the therapeutic benefits, clinical potential and clinical development of budoprutug and CLYM116; expectations regarding the timing of submitting an investigational new drug application or additional clinical trial applications for CLYM116; the anticipated timelines for initiating the Phase 1 clinical trial of CLYM116; the anticipated timelines for dosing the first patient in Climb Bio’s Phase 2 clinical trial of budoprutug in primary membranous nephropathy and Phase 1 clinical trial of CLYM116; the anticipated timelines for announcing data from Climb Bio’s ongoing and planned clinical trials; the sufficiency of Climb Bio’s cash resources for the period anticipated; and other statements containing the words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “would,” “will,” “working” and similar expressions. Forward-looking statements are based on management’s current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in, or implied by, such forward-looking statements. Climb Bio may not actually achieve the plans, intentions or expectations disclosed in these forward-looking statements, and you should not place undue reliance on these forward-looking statements. These risks and uncertainties include, but are not limited to, important risks and uncertainties associated with: the ability of Climb Bio to timely and successfully achieve or recognize the anticipated benefits of its acquisition of Tenet Medicines, Inc. and its technology transfer and exclusive license agreement with Beijing Mabworks Biotech Co., Ltd.; Climb Bio’s ability to advance budoprutug and CLYM116 on the timelines expected or at all and to obtain and maintain necessary approvals from the U.S. Food and Drug Administration and other regulatory authorities; obtaining and maintaining the necessary approvals from investigational review boards at clinical trial sites and independent data safety monitoring boards; replicating in clinical trials positive results found in early-stage clinical trials or nonclinical studies; competing successfully with other companies that are seeking to develop treatments for primary membranous nephropathy, immune thrombocytopenia, systemic lupus erythematosus, IgA nephropathy and other immune-mediated diseases; maintaining or protecting intellectual property rights related to budoprutug, CLYM116 and/or its other product candidates; managing expenses; changes in applicable laws or regulation; the possibility that Climb Bio may be adversely affected by other economic, business and/or competitive factors; and raising the substantial additional capital needed, on the timeline necessary, to continue development of budoprutug, CLYM116 and any other product candidates Climb Bio may develop. For a discussion of other risks and uncertainties, and other important factors, any of which could cause Climb Bio’s actual results to differ materially from those contained in the forward-looking statements, see the “Risk Factors” section, as well as discussions of potential risks, uncertainties and other important factors, in Climb Bio’s most recent filings with the U.S. Securities and Exchange Commission. In addition, the forward-looking statements included in this press release represent Climb Bio’s views as of the date hereof and should not be relied upon as representing Climb Bio’s views as of any date subsequent to the date hereof. Climb Bio anticipates that subsequent events and developments will cause Climb Bio’s views to change. However, while Climb Bio may elect to update these forward-looking statements at some point in the future, Climb Bio specifically disclaims any obligation to do so, except as required by law. Investors and Media Carlo Tanzi, Ph.D. Kendall Investor Relations [email protected]

Clinical Trials of Budoprutug in Immune Thrombocytopenia (ITP) and Systemic Lupus Erythematosus (SLE) Underway; Trial of Budoprutug in Primary Membranous Nephropathy (pMN) Expected to Initiate in the Coming Weeks Budoprutug Subcutaneous Formulation Demonstrated High Bioavailability and Favorable Tolerability in Non-clinical Studies; Phase 1 Trial Expected to Initiate in the Coming Weeks, with Initial Data Anticipated in First Half 2026 CLYM116 Focused Webcast Event, Including New Preclinical Data, Planned for September 2025; IND or CTA Submission for IgA Nephropathy (IgAN) Expected in Second Half 2025 Edgar D. Charles, M.D., MSc Appointed Chief Medical Officer Strong Financial Position, with Cash Runway Expected Through 2027 WELLESLEY HILLS, Mass., Aug. 12, 2025 (GLOBE NEWSWIRE) -- Climb Bio, Inc. (Nasdaq: CLYM), a clinical-stage biotechnology company developing therapeutics for patients with immune-mediated diseases, today reported financial results for the second quarter ended June 30, 2025 and provided business updates. “I am extremely proud of what the Climb Bio team has accomplished this year – we have executed with focus and discipline, building the team and advancing our pipeline. We have now dosed patients in both the ITP and SLE clinical trials of budoprutug, our anti-CD19 monoclonal antibody, and achieved regulatory clearance to initiate the pMN Phase 2 trial and the Phase 1 trial of subcutaneous budoprutug in healthy volunteers, both of which are expected to begin shortly,” said Aoife Brennan, President and CEO of Climb Bio. “We are also making exciting progress with CLYM116, our differentiated anti-APRIL antibody that we believe could be a best-in-class treatment for IgAN and other indications. This execution momentum sets up a data-rich period ahead, beginning with an investor event planned for September 2025 to showcase our CLYM116 program, share supportive preclinical data, and discuss our IgAN development plans.” Second Quarter 2025 and Recent Highlights Budoprutug Program Updates Phase 1b/2a immune thrombocytopenia (ITP) trial FPI achieved, enrollment ongoing. Climb Bio is enrolling an open-label, dose-escalation Phase 1b/2a clinical trial of budoprutug in patients with ITP to evaluate safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary efficacy, including B cell depletion and platelet counts. Phase 1b systemic lupus erythematosus (SLE) trial FPI achieved, enrollment ongoing. Climb Bio is enrolling an open-label, dose-escalation Phase 1b clinical trial of budoprutug in patients with SLE to evaluate safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary efficacy, including B cell depletion, autoantibody levels, and clinical activity. Phase 2 primary membranous nephropathy (pMN) trial on track to initiate in coming weeks. The pMN trial, an open-label, dose-ranging Phase 2 clinical trial, is designed to further evaluate safety, pharmacokinetics, pharmacodynamics, including B cell depletion and anti-PLA2R antibody levels, and preliminary efficacy, including complete and partial remission. Start-up activities are underway, and the Company expects to initiate the Phase 2 trial in the coming weeks. Continued development of subcutaneous (SC) formulation. Climb Bio obtained supportive non-clinical data for its budoprutug SC formulation, which demonstrated high bioavailability and favorable tolerability. A Clinical Trial Application was cleared in Australia in August, and the Company expects to initiate a Phase 1 trial in healthy volunteers in the coming weeks. Initial Phase 1 trial results for the budoprutug SC formulation are expected in the first half of 2026. CLYM116 Program Updates CLYM116, an antibody targeting the APRIL pathway for IgA nephropathy (IgAN), advancing toward clinical development. Climb Bio remains on track to submit an Investigational New Drug (IND) or Clinical Trial Application (CTA) for CLYM116 in IgAN in the second half of 2025. The Company plans to host a CLYM116-focused investor event in September 2025, where preclinical data on CLYM116, including head-to-head data in nonhuman primates with a first-generation anti-APRIL, will be shared. Corporate Updates Appointed Edgar D. Charles, M.D., MSc as Chief Medical Officer in June 2025. Dr. Charles brings over 20 years of experience in immunology-focused pharmaceutical development, academic research, and clinical medicine to the role. He joins Climb Bio from Bristol Myers Squibb (BMS), where he held clinical roles of increasing responsibility since joining in 2015, leading the development of a number of therapeutic candidates through IND, Phase 1-4 clinical trials, and FDA product approval. Dr. Charles most recently served as Vice President and Senior Global Program Lead, Immunology at BMS, where he led the immunology global program organization, overseeing strategy and execution across a diverse immune therapeutics pipeline spanning rheumatology, pulmonology, dermatology, and gastroenterology. Before his tenure at BMS, Dr. Charles held roles at Merck & Co., where he led global clinical development programs in infectious diseases and vaccines, and served as an Assistant Professor at Rockefeller University, focusing his research on virus-induced autoimmunity and B cell biology. Anticipated Milestones Budoprutug (anti-CD19 monoclonal antibody): pMN Phase 2 study – first patient in (H2 2025) Company to provide guidance on the anticipated timing of clinical readouts in SLE and ITP (H2 2025) Subcutaneous formulation Phase 1 clinical trial in healthy volunteers – first patient in (H2 2025) and initial results (H1 2026) CLYM116 (anti-APRIL monoclonal antibody): Reporting preclinical data (September 2025) and submission of IND or CTA in IgAN (H2 2025) Investor event on CLYM116 to be held in September 2025 Second Quarter 2025 Financial Results Cash Position: Cash, cash equivalents and marketable securities were $187.4 million as of June 30, 2025. Cash, cash equivalents and marketable securities are expected to fund operations through 2027. Research and Development (R&D) expenses: R&D expenses were $6.6 million for the three months ended June 30, 2025, compared to $1.0 million for the comparable period in 2024. Acquired In-Process Research and Development (IPR&D) expense: Acquired IPR&D expense was $51.7 million for the three months ended June 30, 2024, resulting from the Company’s acquisition of Tenet Medicines. There were no IPR&D expenses for the comparable period in 2025. General and Administrative (G&A) expenses: G&A expenses were $4.1 million for the three months ended June 30, 2025, compared to $3.7 million for the comparable period in 2024. Other income, net: Other income, net was $2.0 million for the three months ended June 30, 2025, compared to $1.5 for the comparable period in 2024. About Climb Bio, Inc. Climb Bio, Inc. is a clinical-stage biotechnology company developing therapeutics for patients with immune-mediated diseases. The Company’s pipeline includes, budoprutug, an anti-CD19 monoclonal antibody that has demonstrated B-cell depletion and has potential to treat a broad range of B-cell mediated diseases, and CLYM116, an anti-APRIL monoclonal antibody currently in IND-enabling studies for IgA nephropathy. For more information, please visit climbbio.com. About Budoprutug Budoprutug is a clinical-stage, anti-CD19 monoclonal antibody being developed by Climb Bio to address a broad range of B-cell mediated, immune-driven diseases. Designed with enhanced effector function and low picomolar affinity, budoprutug targets and depletes CD19-expressing B cells, including plasma blasts that are key sources of pathogenic autoantibodies. Climb Bio plans to evaluate budoprutug in multiple clinical trials across three lead indications—primary membranous nephropathy (pMN), immune thrombocytopenia (ITP), and systemic lupus erythematosus (SLE)—which represent distinct mechanistic subtypes of immune-mediated disease. Early clinical data suggest budoprutug may offer durable B-cell depletion, rapid reductions in autoantibodies, and clinical remission in pMN. A subcutaneous formulation is also in development to enable broader patient access and potential home-based dosing. Budoprutug has been granted orphan drug designation by the FDA for the treatment of pMN. About CLYM116 CLYM116 is a preclinical-stage monoclonal antibody targeting APRIL (A Proliferation-Inducing Ligand), a key driver of pathogenic B-cell activity in autoimmune diseases. CLYM116 employs a novel pH-dependent bind-and-release mechanism to potently block APRIL signaling, promote lysosomal degradation of APRIL, and recycle the antibody to extend its half-life. This differentiated design offers the potential for rapid, deep, and durable inhibition of APRIL with a favorable safety profile and less frequent dosing. CLYM116 is being advanced for the treatment of IgA nephropathy (IgAN), with plans to initiate a Phase 1 clinical trial following completion of IND-enabling studies and subject to regulatory clearance. The molecule may also have broader utility across other B-cell mediated diseases where APRIL plays a critical role. Forward-Looking Statements This press release contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, including without limitation statements regarding: future expectations, plans and prospects for Climb Bio; expectations regarding the therapeutic benefits, clinical potential and clinical development of budoprutug and CLYM116; the trial design for the planned clinical trials of budoprutug; the anticipated timelines for initiating clinical trials of budoprutug for primary membranous nephropathy and CLYM116 for IgA nephropathy; plans to optimize the administration of budoprutug; the anticipated benefits of Climb Bio’s license agreement with Mabworks; expectations regarding the timing of an investigational new drug application or clinical trial application submission for CLYM116; anticipated timelines for announcing data from Climb Bio’s ongoing and planned clinical trials; the sufficiency of Climb Bio’s cash resources for the period anticipated; and other statements containing the words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “would,” “will,” “working” and similar expressions. Forward-looking statements are based on management’s current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in, or implied by, such forward-looking statements. Climb Bio may not actually achieve the plans, intentions or expectations disclosed in these forward-looking statements, and you should not place undue reliance on these forward-looking statements. These risks and uncertainties include, but are not limited to, important risks and uncertainties associated with: the ability of Climb Bio to timely and successfully achieve or recognize the anticipated benefits of its acquisition of Tenet Medicines, Inc. and its license agreement with Mabworks; changes in applicable laws or regulation; the possibility that Climb Bio may be adversely affected by other economic, business and/or competitive factors; Climb Bio’s ability to advance budoprutug and CLYM116 on the timelines expected or at all and to obtain and maintain necessary approvals from the U.S. Food and Drug Administration and other regulatory authorities; obtaining and maintaining the necessary approvals from investigational review boards at clinical trial sites and independent data safety monitoring boards; replicating in clinical trials positive results found in early-stage clinical trials; competing successfully with other companies that are seeking to develop treatments for primary membranous nephropathy, immune thrombocytopenia, systemic lupus erythematosus, IgA nephropathy and other immune-mediated diseases; maintaining or protecting intellectual property rights related to budoprutug, CLYM116 and/or its other product candidates; managing expenses; and raising the substantial additional capital needed, on the timeline necessary, to continue development of budoprutug, CLYM116 and any other product candidates Climb Bio may develop. For a discussion of other risks and uncertainties, and other important factors, any of which could cause Climb Bio’s actual results to differ materially from those contained in the forward-looking statements, see the “Risk Factors” section, as well as discussions of potential risks, uncertainties and other important factors, in Climb Bio’s most recent filings with the U.S. Securities and Exchange Commission. In addition, the forward-looking statements included in this press release represent Climb Bio’s views as of the date hereof and should not be relied upon as representing Climb Bio’s views as of any date subsequent to the date hereof. Climb Bio anticipates that subsequent events and developments will cause Climb Bio’s views to change. However, while Climb Bio may elect to update these forward-looking statements at some point in the future, Climb Bio specifically disclaims any obligation to do so, except as required by law. Investors and Media Carlo Tanzi, Ph.D. Kendall Investor Relations [email protected]

Clinical Trials of Budoprutug in Primary Membranous Nephropathy (pMN), Immune Thrombocytopenia (ITP), and Systemic Lupus Erythematosus (SLE) on Track to Initiate in 2025 CLYM116 Progressing Towards Anticipated IND or CTA Submission in Second Half 2025 Appointed Kim Cobleigh Drapkin, CPA, and Bo Cumbo as Independent Directors and Perrin Wilson, Ph.D., as Chief Business Officer Strong Financial Position, with Cash Runway Expected Through 2027 WELLESLEY HILLS, Mass., May 14, 2025 (GLOBE NEWSWIRE) -- Climb Bio, Inc. (Nasdaq: CLYM), a clinical stage biotechnology company developing therapeutics for patients with immune-mediated diseases, today reported financial results for the first quarter ended March 31, 2025, and provided business updates. “2025 is a critical year of execution for Climb Bio and we continue to make excellent progress developing a differentiated pipeline targeting immune-mediated diseases with expansive therapeutic and commercial potential,” said Aoife Brennan, President and CEO of Climb Bio. “Our most advanced program, budoprutug, a potential best-in-class anti-CD19 monoclonal antibody designed to treat B-cell mediated diseases, remains on track to initiate clinical studies in ITP and SLE in the coming weeks and in pMN in the second half of 2025. We plan to provide clarity on the anticipated timing of clinical readouts later this year when enrollment dynamics are clearer. In parallel, we are advancing the subcutaneous formulation of budoprutug and subject to regulatory clearance, anticipate initiating a Phase 1 clinical trial in healthy volunteers in the second half of the year.” Dr. Brennan continued, “We have also made progress with our CLYM116 program, a potential best-in-class anti-APRIL monoclonal antibody with potential to provide therapeutic benefit to patients living with IgA nephropathy and other B-cell mediated diseases. We look forward to sharing detailed preclinical data from the program, including pharmacokinetic and pharmacodynamic markers of biological activity, in the second half of 2025 and we anticipate submitting an investigational new drug (IND) or clinical trial application (CTA) for CLYM116 by year end.”  First Quarter 2025 and Recent Highlights FDA clearance for budoprutug Phase 2 pMN clinical trial. In March 2025, the Company announced that it had received clearance from the FDA to initiate a Phase 2 clinical trial of budoprutug in patients with pMN. This open-label, dose-ranging trial is designed to further evaluate the efficacy and safety of budoprutug in pMN. FDA clearance of budoprutug IND in ITP. In March 2025, the Company announced that it had received clearance from the FDA of its IND to initiate a Phase 1b/2a clinical trial of budoprutug in patients with ITP. In parallel, the Company is also pursuing ex-U.S. regulatory clearance for this clinical trial. This open-label, dose escalation and expansion trial is designed to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary clinical efficacy of budoprutug in ITP. Pursuing ex-U.S. regulatory clearance for budoprutug clinical trial in SLE. Following the Company’s receipt of clearance from the FDA of its IND for SLE, the Company is also pursuing regulatory clearance to initiate the Phase 1b clinical trial of budoprutug in SLE at sites outside the United States. The open-label, single ascending dose study is designed to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary signs of clinical efficacy of budoprutug in SLE. Completed studies supporting a cell line switch for budoprutug. In March 2025, the Company announced that it was advancing the productivity and scalability of the manufacturing process for budoprutug to support later-stage clinical development. Expanded pipeline to include CLYM116, an antibody targeting the APRIL pathway for IgAN. In January 2025, Climb Bio entered into a technology transfer and exclusive license agreement with Beijing Mabworks Biotech Co., Ltd. (Mabworks) for the rights to develop and commercialize CLYM116 in the territory outside of Greater China. CLYM116 is a highly potent, Fc-engineered antibody that has the potential to enable more rapid, deep, and durable inhibition of APRIL signaling through its novel, pH-dependent mechanism of action. CLYM116 is currently in IND-enabling studies and the Company anticipates submitting an IND or CTA by year end. Appointed Kim Cobleigh Drapkin, CPA, and Bo Cumbo as Independent Directors in April 2025. Kim Cobleigh Drapkin, CPA, is a seasoned financial leader with over 30 years of experience guiding private and publicly traded biotechnology and pharmaceutical companies through strategic growth, financial planning, capital raises, and transformative transactions. Ms. Drapkin most recently served as Chief Executive Officer of Graphite Bio. Bo Cumbo brings over 30 years of experience in the pharmaceutical and biotechnology industries, with a proven track record of leading successful commercial launches for 11 specialty and rare disease therapies. Mr. Cumbo currently serves as President, Chief Executive Officer, and Director of Solid Biosciences. Appointed Perrin Wilson, Ph.D., as Chief Business Officer in February 2025. Dr. Wilson has over 17 years of experience in the pharmaceutical and biotech industry and has deep expertise in business development and commercial strategy. During her career, she has led brand strategy and launch preparations and has overseen multiple successful acquisitions and integrations. Anticipated Milestones Budoprutug (anti-CD19 monoclonal antibody): ITP Phase 1b/2a study - first patient in (H1 2025) SLE Phase 1b study - first patient in (H1 2025) pMN Phase 2 study - first patient in (H2 2025) Subcutaneous formulation - obtain additional non-clinical data (H1 2025) and initiation of a Phase 1 clinical trial in healthy volunteers (H2 2025) CLYM116 (anti-APRIL monoclonal antibody): Reporting preclinical data (H2 2025) and submission of IND or CTA (H2 2025) First Quarter 2025 Financial Results Cash Position: Cash, cash equivalents and marketable securities were $197.8 million as of March 31, 2025. Cash, cash equivalents and marketable securities are expected to fund operations through 2027. Research and Development (R&D) expenses: R&D expenses were $17.3 million for the three months ended March 31, 2025, including the $9.0 million upfront payment made to Mabworks in accordance with the license agreement, compared to $1.1 million for the comparable period in 2024. General and Administrative (G&A) expenses: G&A expenses were $5.7 million for the three months ended March 31, 2025, compared to $1.9 million for the comparable period in 2024. Other income, net: Other income, net was $2.2 million for the three months ended March 31, 2025, compared to $1.3 for the comparable period in 2024. About Climb Bio, Inc.Climb Bio, Inc. is a clinical-stage biotechnology company developing therapeutics for patients with immune-mediated diseases. The Company’s pipeline includes, budoprutug, an anti-CD19 monoclonal antibody that has demonstrated B-cell depletion and has potential to treat a broad range of B-cell mediated diseases, and CLYM116, an anti-APRIL monoclonal antibody currently in IND-enabling studies for IgA nephropathy. For more information, please visit climbbio.com. About BudoprutugBudoprutug is a clinical-stage, anti-CD19 monoclonal antibody being developed by Climb Bio to address a broad range of B-cell mediated, immune-driven diseases. Designed with enhanced effector function and low picomolar affinity, budoprutug targets and depletes CD19-expressing B cells, including plasma blasts that are key sources of pathogenic autoantibodies. Climb Bio plans to evaluate budoprutug in multiple clinical trials across three lead indications—primary membranous nephropathy (pMN), immune thrombocytopenia (ITP), and systemic lupus erythematosus (SLE)—which represent distinct mechanistic subtypes of immune-mediated disease. Early clinical data suggest budoprutug may offer durable B-cell depletion, rapid reductions in autoantibodies, and clinical remission in pMN. A subcutaneous formulation is also in development to enable broader patient access and potential home-based dosing. Budoprutug has been granted orphan drug designation by the FDA for the treatment of pMN. About CLYM116CLYM116 is a preclinical-stage monoclonal antibody targeting APRIL (A Proliferation-Inducing Ligand), a key driver of pathogenic B-cell activity in autoimmune diseases. CLYM116 employs a novel pH-dependent bind-and-release mechanism to potently block APRIL signaling, promote lysosomal degradation of APRIL, and recycle the antibody to extend its half-life. This differentiated design offers the potential for rapid, deep, and durable inhibition of APRIL with a favorable safety profile and less frequent dosing. CLYM116 is being advanced for the treatment of IgA nephropathy (IgAN), with plans to initiate a Phase 1 clinical trial following completion of IND-enabling studies and subject to regulatory clearance. The molecule may also have broader utility across other B-cell mediated diseases where APRIL plays a critical role. Forward-Looking StatementsThis press release contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, including without limitation statements regarding: future expectations, plans and prospects for Climb Bio; expectations regarding the therapeutic benefits, clinical potential and clinical development of budoprutug and CLYM116; the trial design for the planned clinical trials of budoprutug; the anticipated timelines for initiating clinical trials of budoprutug for primary membranous nephropathy, immune thrombocytopenia and systemic lupus erythematosus; plans to optimize the administration of budoprutug; the anticipated benefits of Climb Bio’s license agreement with Mabworks; expectations regarding the timing of an investigational new drug application or clinical trial application submission for CLYM116; the sufficiency of Climb Bio’s cash resources for the period anticipated; and other statements containing the words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “would,” “will,” “working” and similar expressions. Forward-looking statements are based on management’s current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in, or implied by, such forward-looking statements. Climb Bio may not actually achieve the plans, intentions or expectations disclosed in these forward-looking statements, and you should not place undue reliance on these forward-looking statements. These risks and uncertainties include, but are not limited to, important risks and uncertainties associated with: the ability of Climb Bio to timely and successfully achieve or recognize the anticipated benefits of its acquisition of Tenet Medicines, Inc. and its license agreement with Mabworks; changes in applicable laws or regulation; the possibility that Climb Bio may be adversely affected by other economic, business and/or competitive factors; Climb Bio’s ability to advance budoprutug and CLYM116 on the timelines expected or at all and to obtain and maintain necessary approvals from the U.S. Food and Drug Administration and other regulatory authorities; obtaining and maintaining the necessary approvals from investigational review boards at clinical trial sites and independent data safety monitoring boards; replicating in clinical trials positive results found in early-stage clinical trials; competing successfully with other companies that are seeking to develop treatments for primary membranous nephropathy, immune thrombocytopenia, systemic lupus erythematosus, IgA nephropathy and other immune-mediated diseases; maintaining or protecting intellectual property rights related to budoprutug, CLYM116 and/or its other product candidates; managing expenses; and raising the substantial additional capital needed, on the timeline necessary, to continue development of budoprutug, CLYM116 and any other product candidates Climb Bio may develop. For a discussion of other risks and uncertainties, and other important factors, any of which could cause Climb Bio’s actual results to differ materially from those contained in the forward-looking statements, see the “Risk Factors” section, as well as discussions of potential risks, uncertainties and other important factors, in Climb Bio’s most recent filings with the U.S. Securities and Exchange Commission. In addition, the forward-looking statements included in this press release represent Climb Bio’s views as of the date hereof and should not be relied upon as representing Climb Bio’s views as of any date subsequent to the date hereof. Climb Bio anticipates that subsequent events and developments will cause Climb Bio’s views to change. However, while Climb Bio may elect to update these forward-looking statements at some point in the future, Climb Bio specifically disclaims any obligation to do so, except as required by law. Investors and MediaCarlo Tanzi, Ph.D.Kendall Investor [email protected]

Received Clearance from the U.S. Food and Drug Administration (FDA) for Clinical Trials of Budoprutug in Primary Membranous Nephropathy (pMN), Immune Thrombocytopenia (ITP), and Systemic Lupus Erythematosus (SLE) Completed Studies to Support Process Optimization through Cell Line Switch for Budoprutug and Filed Additional Patent Applications to Further Strengthen Intellectual Property Position Expanded Pipeline to Include CLYM116, an Anti-APRIL (A PRoliferation-Inducing Ligand) Monoclonal Antibody for Treatment of IgA Nephropathy (IgAN) Appointed Perrin Wilson, Ph.D. as Chief Business Officer Ended 2024 in a Strong Financial Position, with Cash Runway Expected Through 2027 WELLESLEY HILLS, Mass., March 25, 2025 (GLOBE NEWSWIRE) -- Climb Bio, Inc. (Nasdaq: CLYM), a clinical stage biotechnology company developing therapeutics for patients with immune-mediated diseases, today reported financial results for the quarter and year ended December 31, 2024, provided a business update, and reiterated anticipated program milestones. “2024 was a transformational year for Climb Bio, as we rebranded the company and embarked on our mission to bring more inspired medicines to patients living with immune-mediated diseases,” said Aoife Brennan, President and CEO of Climb Bio. “Our momentum continues in 2025, which marks a critical year of execution across our portfolio. Our cornerstone asset, budoprutug, a potentially best-in-class anti-CD19 monoclonal antibody, is being developed for three initial indications: pMN, ITP, and SLE, each of which represents a significant opportunity where we believe budoprutug is differentiated and uniquely positioned to deliver meaningful outcomes for patients. With regulatory clearance from the FDA now in place for clinical trials in all three indications, we have begun initiating clinical trials and expect to begin dosing patients later this year.” Dr. Brennan continued, “Additionally, we recently in-licensed a second asset, CLYM116, a potential best-in-class anti-APRIL monoclonal antibody currently in Investigational New Drug (IND)-enabling studies for the treatment of IgAN and other B-cell mediated diseases. We remain focused on progressing this program towards the clinic and expect to share initial preclinical data in the second half of 2025. With two highly differentiated assets in our pipeline, a strong balance sheet, and a deeply experienced team, we are well positioned to execute on our goals and advance new treatment options for the approximately 50 million people in the U.S. living with immune-mediated diseases.” Recent Highlights FDA Clearance for budoprutug Phase 2 pMN clinical trial. The Company received clearance from the FDA to initiate a Phase 2 clinical trial of budoprutug in patients with pMN. This open-label, dose-ranging trial is designed to further evaluate the efficacy and safety of budoprutug in pMN. FDA Clearance of budoprutug IND in ITP. The Company received clearance from the FDA of its IND, allowing the Company to initiate a Phase 1b/2a clinical trial of budoprutug in patients with ITP. This open-label, dose escalation and expansion trial is designed to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary clinical efficacy of budoprutug in ITP. Completed studies supporting a cell line switch for budoprutug and filed patent applications to strengthen intellectual property position. The Company is advancing the manufacturing process for budoprutug to support later stage clinical development and recently completed studies supporting a cell line switch that allows for improved productivity and scalability. The material from the new process has been cleared by the FDA for use in clinical trials. The Company has filed multiple patent applications that relate to the new manufacturing process, new uses of budoprutug, and new formulations. The patents that may be issued from these pending patent applications are expected to expire in 2045. Expanded pipeline to include CLYM116, an antibody targeting the APRIL pathway for IgAN. In January 2025, Climb Bio entered into a technology transfer and exclusive license agreement with Beijing Mabworks Biotech Co., Ltd. (NEEQ Code: 874070, Mabworks) for the rights to develop and commercialize CLYM116 in the territory outside of Greater China. CLYM116 is a highly potent, Fc-engineered antibody which has the potential to enable more rapid, deep and durable inhibition of APRIL signaling through its novel, pH-dependent mechanism of action. Appointed Perrin Wilson, Ph.D. as Chief Business Officer in February 2025. Dr. Wilson has over 17 years of experience in the pharmaceutical and biotech industry and has deep expertise in business development and commercial strategy. During her career, she has led brand strategy and launch preparations and has overseen multiple successful acquisitions and integrations. Portfolio Overview and Anticipated Key Milestones Budoprutug: anti-CD19 monoclonal antibody designed for a broad range of B-cell mediated diseases. Primary membranous nephropathy (pMN): pMN is an IgG4 mediated disease, with no approved treatment options. A Phase 1b trial of budoprutug in pMN has been completed and the Company has received clearance from the FDA to initiate a Phase 2 clinical trial. The Company anticipates dosing its first patient in this study in the second half of 2025. Immune thrombocytopenia (ITP): ITP is an IgG 1-3 immune-mediated disorder where there is compelling proof-of-concept validating the clinical rationale for using B-cell depletion therapies. The Company now has clearance from the FDA to initiate a Phase 1b/2a clinical trial of budoprutug in ITP and anticipates dosing its first patient in the first half of 2025. Systemic lupus erythematosus (SLE): SLE is a complex, chronic systemic disease affecting multiple organ systems where there is proof-of-concept for a CD19-targeted approach. Following the Company’s receipt of clearance of the IND for SLE in October 2024, the Company remains on track to initiate a Phase 1b clinical study of budoprutug for SLE and anticipates dosing its first patient in the first half of 2025. Subcutaneous formulation: Budoprutug has been successfully formulated above 175 mg/ml while maintaining low viscosity, creating an opportunity to pursue a dosing form that potentially features a low volume injection. The Company plans to share additional non-clinical data for the subcutaneous program in the first half of 2025 and plans to progress the subcutaneous program into clinical development in the second half of 2025. CLYM116: anti-APRIL monoclonal antibody for IgAN and other B-cell mediated diseases. IgA nephropathy (IgAN): IgAN is an autoantibody mediated disease caused by deposition of immune complexes, comprising IgA and IgG, in the glomeruli, where there is clinical validation for an APRIL targeted approach. IND-enabling studies for CLYM116 are ongoing and the Company expects to share initial preclinical data from this program in the second half of 2025. Fourth Quarter and Full Year 2024 Financial Results Cash Position: Cash, cash equivalents and marketable securities were $212.5 million as of December 31, 2024, as compared to $106.8 million as of December 31, 2023. Cash, cash equivalents and marketable securities are expected to fund operations through 2027. Acquired In-Process Research and Development expense: Acquired in-process research and development expense was $51.7 million for the full year ended December 31, 2024 relating to the Company’s acquisition of Tenet Medicines, Inc. in June of 2024. Research and Development (R&D) expenses: R&D expenses were $6.0 million for the three months ended December 31, 2024, and $14.3 million for the full year 2024, compared to $3.1 million and $15.4 million for comparable periods in 2023, respectively. General and Administrative (G&A) expenses: G&A expenses were $5.0 million for the three months ended December 31, 2024, and $16.0 million for the full year 2024, compared to $2.0 million and $24.9 million for comparable periods in 2023, respectively. Other income, net: Other income, net was $2.5 million for the three months ended December 31, 2024, and $8.1 million for the full year 2024, compared to $1.5 million and $5.2 million for comparable periods in 2023, respectively. Net loss: Net loss was $8.4 million for the three months ended December 31, 2024, and $73.9 million for the full year 2024, compared to $3.6 million and $35.1 million for comparable periods in 2023, respectively. Net loss for the full year 2024 included $51.7 million of acquired in-process research and development expenses, while net loss for the full year 2023 included restructuring costs of $18.8 million, of which $3.8 million was included in R&D expenses and $15.0 million in G&A expenses. About Climb Bio, Inc.Climb Bio, Inc. is a clinical-stage biotechnology company developing therapeutics for patients with immune-mediated diseases. The Company’s pipeline includes, budoprutug, an anti-CD19 monoclonal antibody that has demonstrated B-cell depletion and has potential to treat a broad range of B-cell mediated diseases, and CLYM116, an anti-APRIL monoclonal antibody currently in IND-enabling studies for IgA nephropathy. For more information, please visit climbbio.com. Forward-Looking StatementsThis press release contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, including without limitation statements regarding: future expectations, plans and prospects for Climb Bio; expectations regarding the therapeutic benefits, clinical potential and clinical development of budoprutug and CLYM116; the trial design for the planned clinical trials of budoprutug; the anticipated timelines for initiating clinical trials of budoprutug for primary membranous nephropathy, immune thrombocytopenia and systemic lupus erythematosus; plans to optimize the administration of budoprutug; the anticipated benefits of Climb Bio’s license agreement with Mabworks; the sufficiency of Climb Bio’s cash resources for the period anticipated; and other statements containing the words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “would,” “will,” “working” and similar expressions. Forward-looking statements are based on management’s current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in, or implied by, such forward-looking statements. Climb Bio may not actually achieve the plans, intentions or expectations disclosed in these forward-looking statements, and you should not place undue reliance on these forward-looking statements. These risks and uncertainties include, but are not limited to, important risks and uncertainties associated with: the ability of Climb Bio to timely and successfully achieve or recognize the anticipated benefits of its acquisition of Tenet Medicines, Inc. and its license agreement with Mabworks; changes in applicable laws or regulation; the possibility that Climb Bio may be adversely affected by other economic, business and/or competitive factors; Climb Bio’s ability to advance budoprutug and CLYM116 on the timelines expected or at all and to obtain and maintain necessary approvals from the U.S. Food and Drug Administration and other regulatory authorities; obtaining and maintaining the necessary approvals from investigational review boards at clinical trial sites and independent data safety monitoring boards; replicating in clinical trials positive results found in early-stage clinical trials; competing successfully with other companies that are seeking to develop treatments for primary membranous nephropathy, immune thrombocytopenia, systemic lupus erythematosus, IgA nephropathy and other immune-mediated diseases; maintaining or protecting intellectual property rights related to budoprutug, CLYM116 and/or its other product candidates; managing expenses; and raising the substantial additional capital needed, on the timeline necessary, to continue development of budoprutug, CLYM116 and any other product candidates Climb Bio may develop. For a discussion of other risks and uncertainties, and other important factors, any of which could cause Climb Bio’s actual results to differ materially from those contained in the forward-looking statements, see the “Risk Factors” section, as well as discussions of potential risks, uncertainties and other important factors, in Climb Bio’s most recent filings with the U.S. Securities and Exchange Commission. In addition, the forward-looking statements included in this press release represent Climb Bio’s views as of the date hereof and should not be relied upon as representing Climb Bio’s views as of any date subsequent to the date hereof. Climb Bio anticipates that subsequent events and developments will cause Climb Bio’s views to change. However, while Climb Bio may elect to update these forward-looking statements at some point in the future, Climb Bio specifically disclaims any obligation to do so, except as required by law. InvestorsChris Brinzey ICR [email protected] MediaJon YuICR [email protected]