Climb Bio, Inc. (CLYM) SEC Filings

Climb Bio, Inc. (CLYM) has a director, Stephen Thomas, filing a notice under Rule 144 to potentially sell up to 100,000 shares of common stock. The shares relate to Performance Stock Units acquired from the issuer on August 7, 2025. As of September 15, 2026, 57,436,255 shares of common stock were outstanding and listed on NASDAQ.

Climb Bio, Inc. (CLYM) reported positive initial Phase 1 data for CLYM116, its anti‑APRIL monoclonal antibody being developed for IgA nephropathy. In healthy volunteers, a single 320 mg subcutaneous dose produced an estimated half‑life of about 29 days and dose‑proportional exposure without evidence of target‑mediated drug disposition at effective dose levels.

The 320 mg dose achieved near‑complete APRIL suppression, with more than 90% free APRIL reduction maintained through 10 weeks and above 75% through 12 weeks, alongside roughly 60–75% reductions in IgA, Gd‑IgA1, and IgM over 12 weeks. CLYM116 was generally well‑tolerated, with no serious adverse events, dose‑limiting toxicities, Grade ≥3 adverse events, discontinuations, or hypogammaglobulinemia; common treatment‑emergent events included headache, upper respiratory tract infection, and mild injection‑site reactions. Based on integrated PK/PD modeling, Climb Bio has defined a target regimen of an 800 mg loading dose followed by 400 mg every 12 weeks and is enrolling the NAVIGATE‑2 Phase 2 IgA nephropathy study, with initial data expected in the first half of 2027 and a Phase 3 initiation planned in 2027 subject to regulatory feedback.

Climb Bio, Inc. received an amended institutional ownership report from MPM BioImpact LLC stating that it no longer holds any of the company’s common stock. MPM BioImpact reports 0 shares beneficially owned, representing 0.0% of the class, with no voting or dispositive power over any shares.

Climb Bio, Inc. reports that its collaborator Beijing Mabworks Biotech Co., Ltd. has dosed the first patient with immunoglobulin A nephropathy in a Phase 2 clinical trial in China. The study is being conducted under a collaboration between the two companies focused on this kidney disease indication.

Climb Bio, Inc. is a clinical-stage biotech developing budoprutug and CLYM116 for immune‑mediated diseases. For the quarter ended June 30, 2026 it reported a net loss of $13.5 million, wider than $8.7 million a year earlier, driven mainly by higher research and development and general and administrative expenses.

For the first six months of 2026, the net loss was $27.2 million versus $29.4 million in 2025 as prior‑year spending included a $9.0 million upfront CLYM116 license payment. Cash, cash equivalents and marketable securities totaled $239.2 million, including $103.4 million of net proceeds from an April 2026 private placement, which the company expects will fund operations into the second half of 2028.

The pipeline advanced with ongoing Phase 2 development of budoprutug in primary membranous nephropathy, Phase 1b/2a trials in immune thrombocytopenia and systemic lupus erythematosus, and a subcutaneous formulation showing robust B‑cell depletion in Phase 1. CLYM116 completed Phase 1 dosing in healthy volunteers, with pharmacokinetic and pharmacodynamic data expected in late 2026, while multiple partnered and in‑licensed programs carry substantial future milestone and royalty obligations.

Climb Bio, Inc. reported results for the quarter ended June 30, 2026 and highlighted progress across its budoprutug and CLYM116 programs. For CLYM116, the company plans an R&D Spotlight on September 3, 2026 to review initial Phase 1 PK/PD data in healthy volunteers and development plans in IgA nephropathy, and anticipates initiating dosing in a Phase 2 IgA nephropathy trial in the third quarter of 2026. A partner-led Phase 1/2 study in IgA nephropathy in China is also ongoing, with Phase 2 dosing expected to begin in the third quarter of 2026.

For budoprutug, enrollment continues in the global PrisMN Phase 2 trial in primary membranous nephropathy, with initial pharmacodynamic data from the low-dose cohort expected in the fourth quarter of 2026. Additional data in immune thrombocytopenia, systemic lupus erythematosus and from a subcutaneous formulation study are expected through late 2026 and 2027. The company completed a private placement on April 29, 2026 generating approximately $110 million in gross proceeds, supporting continued clinical advancement and extending its cash runway into the second half of 2028. Cash, cash equivalents and marketable securities totaled $239.2 million as of June 30, 2026. For the quarter, R&D expenses were $9.7 million, G&A expenses were $5.6 million, and other income, net was $1.9 million; the company reported a net loss for the period.

FMR LLC reports beneficial ownership of 6,790,364 shares of CLIMB BIO INC common stock, representing 11.9% of the class as of 06/30/2026. The filing (Schedule 13G) states FMR LLC holds sole dispositive power over these shares and identifies Abigail P. Johnson as having dispositive power. The report lists the issuer CUSIP 28658R106 and provides FMR's principal office in Boston.

RA Capital Management and affiliates updated their ownership disclosure in Climb Bio, Inc., reporting a sizable stake and a board change. The reporting group beneficially owns 23,249,186 shares of common stock, representing 33.0% of the company, including shares underlying pre-funded warrants and stock options exercisable within 60 days.

The filing explains that RA Capital advises multiple funds and accounts that hold Climb Bio securities and has delegated voting and investment power over those positions. A "Beneficial Ownership Blocker" in the pre-funded warrants limits exercises so the group cannot exceed 33.0% ownership. The amendment also notes that on June 29, 2026, RA Capital analyst Dr. Breanna Celebi was appointed to Climb Bio’s board of directors as RA Capital’s designee, replacing Dr. Andrew Levin, who resigned the same day. Additionally, on July 2, 2026, Sera Medicines made a pro rata in-kind distribution of 2,479,872 Climb Bio shares to its members, with RA Capital funds receiving portions of those shares.

Climb Bio, Inc. reported a Form 4 showing a grant of stock options tied to 70,284 shares of common stock at an exercise price of $13.36 per share. The options vest in equal monthly installments from June 29, 2026 over three years and expire on June 29, 2036. The options are held by Ms. Celebi for the benefit of several RA Capital funds and an account, and any net cash or stock received upon exercise must be turned over to RA Capital Management, offsetting advisory fees. The reporting persons disclaim beneficial ownership of the option and underlying shares except to the extent of any pecuniary interest.