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.
- No serious adverse events, dose limiting toxicities, or adverse event related discontinuations observed.
- All adverse events observed were mild to moderate (Grade 1-2), transient, and self-resolving.
- Injection site reactions observed in two patients, both Grade 1, and resolved without intervention.

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 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 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 Media

Carlo Tanzi, Ph.D.

Kendall Investor Relations

ctanzi@kendallir.com

Climb Bio Presents CLYM116 Initial Phase 1 Safety Data and Translational Modeling Results at European Renal Association (ERA) Congress 2026 Supporting Continued Development