Climb Bio: 3-year Phase 1b data in 4 patients; no grade 3+ AEs

Climb Bio (CLYM) filed an 8-K announcing new long-term follow-up data for budoprutug, an anti‑CD19 monoclonal antibody in development for B‑cell mediated diseases.

Rhea-AI Filing Summary

Climb Bio (CLYM) filed an 8-K announcing new long-term follow-up data for budoprutug, an anti‑CD19 monoclonal antibody in development for B‑cell mediated diseases. An abstract reports results from a previously conducted Phase 1b trial (NCT04652570) in primary membranous nephropathy.

The data showed long-term control of proteinuria for up to three years after initial dosing in four patients who received up to four doses of budoprutug. Three patients required no further immunosuppressive treatment during follow-up. No treatment‑related adverse events grade 3 or higher were observed in the trial.

The company’s forward‑looking statements section references development plans for budoprutug and CLYM116 and outlines risks including clinical progress, regulatory approvals, competition, intellectual property, and capital needs.

Insights

Biotech clinical development analyst

Early Phase 1b signal in 4 patients with favorable safety noted.

The company highlighted an abstract from a Phase 1b study in primary membranous nephropathy showing proteinuria control for up to three years after initial dosing in four patients, with up to four doses administered. Three of these patients did not require additional immunosuppressive therapy, and no treatment‑related adverse events grade 3 or higher were observed.

These findings are encouraging but come from a small Phase 1b cohort, which is typically designed to assess safety and early signals rather than confirm efficacy. The forward‑looking section underscores dependencies on future clinical progress and regulatory interactions, along with competitive and funding considerations.

Further disclosures in company materials may detail larger cohorts, durability across broader populations, and how CLYM116 development proceeds alongside budoprutug.

8-K Event Classification

Item 8.01 — Other Events

1 item

Item 8.01 Other Events Other

Voluntary disclosure of events the company deems important to shareholders but not covered by other items.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What did Climb Bio (CLYM) announce?

The company reported an abstract with long-term follow-up data for budoprutug from a previously conducted Phase 1b trial in primary membranous nephropathy.

What is budoprutug and what disease was studied?

Budoprutug is a novel anti‑CD19 monoclonal antibody; the data come from a Phase 1b study in primary membranous nephropathy.

What efficacy-related outcome was reported for budoprutug?

Long-term control of proteinuria for up to three years after initial dosing in four patients was reported in the abstract.

How many patients and doses were involved in the follow-up data?

The follow-up included four patients, each receiving up to four doses of budoprutug.

Were further immunosuppressive treatments needed?

In three of the four patients, no further immunosuppressive treatment was required during follow-up.

What safety findings were reported?

The trial observed no treatment‑related adverse events grade 3 or higher.

What other programs did Climb Bio reference?

The forward‑looking statements referenced the clinical development of budoprutug and CLYM116.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 10/17/2025 - 12:00 AM Learn about SEC filing dates

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): October 17, 2025

CLIMB BIO, INC.

(Exact Name of Registrant as Specified in its Charter)

Delaware		001-40708		83-2273741
(State or Other Jurisdiction of Incorporation)		(Commission File Number)		(IRS Employer Identification No.)

20 William Street, Suite 145 Wellesley Hills, Massachusetts		02481
(Address of Principal Executive Offices)		(Zip Code)

Registrant’s Telephone Number, Including Area Code: (866) 857-2596

Not Applicable

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class		Trading Symbol(s)		Name of each exchange on which registered
Common Stock, par value $0.0001 per share		CLYM		The Nasdaq Stock Market LLC (The Nasdaq Global Market)

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 8.01 Other Events.

On October 17, 2025, Climb Bio, Inc. (the “Company”) issued a press release announcing the publication of an abstract providing new long-term follow-up clinical data for budoprutug, a novel anti-CD19 monoclonal antibody in development for B-cell mediated diseases. The follow-up clinical data from the previously conducted Phase 1b clinical trial (NCT04652570) of budoprutug in primary membranous nephropathy demonstrated long-term control of proteinuria for up to three years after initial dosing in four patients who received up to four doses of budoprutug. Additionally, in three of the patients, no further immunosuppressive treatment was required. In the trial, no treatment-related adverse events grade 3 or higher were observed.

Forward-Looking Statements

This Current Report on Form 8-K 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 the Company; expectations regarding the therapeutic benefits, clinical potential and clinical development of budoprutug and CLYM116; 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. The Company 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 the Company 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.; the Company’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 preclinical 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 the Company 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 the Company may develop. For a discussion of other risks and uncertainties and other important factors, any of which could cause the Company’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 the Company’s most recent filings with the U.S. Securities and Exchange Commission. In addition, the forward-looking statements included in this Current Report on Form 8-K represent the Company’s views as of the date hereof and should not be relied upon as representing the Company’s views as of any date subsequent to the date hereof. The Company anticipates that subsequent events and developments will cause the Company’s views to change. However, while the Company may elect to update these forward-looking statements at some point in the future, the Company specifically disclaims any obligation to do so, except as required by law.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

						Climb Bio, Inc.
Date: October 17, 2025				By:		/s/ Aoife Brennan
						Aoife Brennan, M.B., Ch.B.
						President and Chief Executive Officer