Climb Bio, Inc.

CLIMB BIO, INC. is a clinical-stage biotechnology company focused on developing therapeutics for immune-mediated diseases, primarily through the strategic acquisition or in-licensing of product candidates with clear biological rationale and well-defined development pathways ⁶. The company operates in the highly competitive and rapidly evolving field of immune-mediated diseases, characterized by significant competition and a strong emphasis on intellectual property ⁶. CLIMB BIO, INC. has incurred significant losses since its inception, with a net loss of $59.9 million ⁴ for the year ended December 31, 2025, and an accumulated deficit of $289.7 million ⁵ as of the same date. The company currently has no source of product revenue and does not anticipate generating revenue from product sales for the foreseeable future ⁶.

The company's core business model revolves around the research, development, and potential commercialization of product candidates for immune-mediated diseases. Revenue generation is currently absent, and the business model is entirely focused on advancing product candidates through clinical trials and regulatory approval processes ⁶. The primary customer segments, if products are approved, would be patients living with immune-mediated diseases such as primary membranous nephropathy (pMN), immune thrombocytopenia (ITP), systemic lupus erythematosus (SLE), and IgA Nephropathy (IgAN) ⁶. The company estimates a potential patient population of over 500,000 ⁶ in the U.S. across pMN, ITP, SLE, and IgAN, and approximately 2.0 million ⁶ people in the U.S. living with immune-mediated diseases that its product candidates could potentially benefit.

CLIMB BIO, INC.'s lead product candidate is budoprutug, a clinical-stage anti-CD19 monoclonal antibody (mAb) designed to deplete CD19-positive B cells ⁶. The company has worldwide rights to develop and commercialize budoprutug for all indications except oncology ⁶. Initial development for budoprutug is focused on pMN, ITP, and SLE ⁶. In pMN, budoprutug has received orphan-drug designation from the FDA ⁶. A Phase 2 clinical trial (PrisMN) for budoprutug in pMN was cleared by the FDA in March 2025 ⁶, with the first patient dosed in November 2025 ⁶. A Phase 1b/2a clinical trial for budoprutug in ITP received FDA clearance in March 2025 ⁶, and a Phase 1b clinical trial for budoprutug in SLE received FDA clearance in October 2024 ⁶. Additionally, a high-concentration subcutaneous (SC) formulation of budoprutug is being advanced, with a Phase 1 clinical trial initiated in September 2025 ⁶ in healthy volunteers in Australia.

The second major product candidate is CLYM116, a next-generation anti-APRIL (A PRoliferation-Inducing Ligand) mAb for the treatment of IgA Nephropathy (IgAN) and other B-cell mediated diseases ⁶. CLIMB BIO, INC. has rights to develop and commercialize CLYM116 for all indications worldwide outside of Greater China ⁶, obtained through the Mabworks Agreement in January 2025 ⁶. CLYM116 is an Fc-engineered antibody designed to prevent APRIL signaling by blocking binding to its receptors and promoting lysosomal APRIL degradation ⁶. A Phase 1 clinical trial of CLYM116 in healthy volunteers in Australia was initiated in November 2025 ⁶, following CTA clearance in October 2025 ⁶. Mabworks, the company's partner, also received IND clearance in December 2025 ⁶ to initiate a parallel Phase 1/2 clinical trial of CLYM116 in China for healthy volunteers and IgAN patients.

For the fiscal year ended December 31, 2025, CLIMB BIO, INC. reported a net loss of $59.9 million ⁴. As of December 31, 2025, the company held cash, cash equivalents, and marketable securities totaling $160.7 million ⁷. The accumulated deficit stood at $289.7 million ⁵. No revenue from product sales was reported for the period ⁶. The filing does not provide specific figures for gross profit, gross margin, operating income, operating margin, basic EPS, free cash flow, total debt, or net debt.

The filing does not provide year-over-year comparisons for revenue growth by segment, margin expansion or contraction, or notable shifts in business mix, as the company has no product revenue ⁶.

Significant operational developments during the reported fiscal period include the FDA clearance in March 2025 ⁶ for the Phase 2 PrisMN clinical trial of budoprutug in pMN, and the dosing of the first patient in November 2025 ⁶. Also in March 2025 ⁶, FDA clearance was received for a Phase 1b/2a clinical trial of budoprutug in ITP. In October 2024 ⁶, FDA clearance was obtained for a Phase 1b clinical trial of budoprutug in SLE. A separate, parallel Phase 1b clinical trial in SLE patients in China received IND clearance in December 2025 ⁶. The company initiated a Phase 1 clinical trial of the SC formulation of budoprutug in healthy volunteers in Australia in September 2025 ⁶, and dosing has been completed. For CLYM116, the company entered into the Mabworks Agreement in January 2025 ⁶. In October 2025 ⁶, CTA clearance was received in Australia to initiate a Phase 1 clinical trial of CLYM116 in healthy volunteers, with the first subject dosed in December 2025 ⁶. Mabworks also received IND clearance in December 2025 ⁶ for a parallel Phase 1/2 clinical trial of CLYM116 in China. The company completed a cell line switch for budoprutug manufacturing in the first quarter of 2025 ⁶, resulting in approximately ten-fold higher productivity ⁶.

CLIMB BIO, INC. has not issued formal revenue, margin, or EPS guidance for the upcoming period. However, the company believes its existing capital resources of $160.7 million ⁷ as of December 31, 2025, will be sufficient to fund its operations into 2028 ⁶. This estimate is based on current operating plans and assumptions, which are subject to change and could lead to earlier exhaustion of capital ⁶.

A major growth area for the company is the advancement of budoprutug into late-stage development in pMN. The company achieved first-patient-in (FPI) in the PrisMN Phase 2 trial in November 2025 ⁶. This trial is designed to evaluate pharmacodynamics (PD), including B cells, anti-PLA2R, and total immunoglobulin, and preliminary efficacy, including complete and partial remission, in pMN patients with persistent proteinuria despite optimized RAAS inhibition ⁶. The goal is to identify a dose for Phase 3 clinical development ⁶. Initial data from the first, low dose cohort, including B cells and anti-PLA2R, are anticipated in the second half of 2026 ⁶. The company believes budoprutug has the potential to offer deep and durable remissions in pMN, supported by encouraging Phase 1b data and the biological rationale for CD19 in the disease ⁶.

Another significant growth vector is the evaluation of budoprutug in ITP and SLE. Dosing is ongoing in an open-label, dose-escalation Phase 1b/2a clinical trial for ITP, which aims to assess safety, tolerability, pharmacokinetics (PK), PD, and preliminary efficacy, including B-cell depletion and platelet counts ⁶. Initial data from the Phase 1b portion of the ITP trial are anticipated in the second half of 2026 ⁶. Concurrently, dosing is ongoing in a global, open-label, dose-escalation Phase 1b clinical trial of budoprutug in moderate to severe SLE patients, evaluating safety, tolerability, PK, PD, and preliminary efficacy, including augmented B cell and antibody analysis ⁶. Initial data from the global SLE trial are also anticipated in the second half of 2026 ⁶. A separate, parallel Phase 1b clinical trial in SLE patients in China, which will also seek to enroll SLE patients with lupus nephritis (LN), received IND clearance in December 2025 ⁶, with FPI anticipated in the first half of 2026 ⁶.

The company is also advancing a subcutaneous (SC) formulation of budoprutug, which is considered an important strategic and commercial differentiator due to the chronic nature of many autoimmune diseases ⁶. Nonclinical data have demonstrated high bioavailability, B-cell depletion, and favorable tolerability for this SC formulation ⁶. A Phase 1 clinical trial in healthy volunteers in Australia was initiated in September 2025 ⁶, with dosing completed and data anticipated in the first half of 2026 ⁶. This formulation aims to offer a differentiated convenience profile and potential commercial advantage through a low volume injection and potential for self-administration ⁶.

The acceleration of CLYM116 development is a key operational outlook. The company believes CLYM116's differentiated 'sweeper' mechanism, potential for favorable PK, and potent APRIL and IgA suppression position it for meaningful differentiation from other anti-APRIL and BAFF/APRIL programs ⁶. A Phase 1 clinical trial of CLYM116 in healthy volunteers in Australia was initiated in December 2025 ⁶ to evaluate safety, tolerability, PK, PD (including IgA reductions), and immunogenicity. Initial data from this Phase 1 study are anticipated in mid-2026 ⁶. Positive results from this trial could lead to advancement into patients with IgAN ⁶.

CLIMB BIO, INC. plans to continue evaluating external opportunities to expand its pipeline through business development, prioritizing opportunities that leverage its expertise in immune-mediated diseases and nephrology, supported by strong human biology and translational data, with well-defined development pathways and potential for efficient, capital-disciplined development in clearly defined patient populations ⁶. This strategy is demonstrated by the acquisition of Tenet Medicines, Inc. and the Mabworks Agreement ⁶.

The company has identified several structural headwinds and execution risks. It has incurred significant losses since inception and expects to continue incurring substantial losses for the foreseeable future, with no current source of product revenue and no guarantee of future profitability ⁶. The company's future success is dependent on the regulatory approval and commercialization of its product candidates, which is a lengthy, complex, and expensive process with uncertain outcomes ⁶. Preliminary or interim clinical trial results may change, and nonclinical and clinical development in immunology and autoimmune diseases presents inherent challenges such as disease heterogeneity and evolving regulatory expectations ⁶. Difficulties in enrolling or retaining patients in clinical trials could delay development activities ⁶. The company faces significant competition in an environment of rapid technological change, with competitors potentially developing or obtaining regulatory approval for products before CLIMB BIO, INC. or developing superior products ⁶. Estimates of market opportunity and forecasts of market growth for its product candidates may prove inaccurate ⁶.

Geopolitical and macro factors also pose risks. The company's international operations expose it to business, regulatory, political, operational, financial, pricing, and reimbursement risks associated with doing business outside of the U.S. ⁶. This includes multiple, conflicting, and changing laws and regulations, foreign exchange fluctuations, and potential trade restrictions or sanctions, particularly with respect to China ⁶. For example, recent and proposed U.S. legislation, such as the BIOSECURE Act, could restrict or prohibit federal funding for contracts with certain Chinese biotechnology companies, potentially impacting CLIMB BIO, INC.'s ability to work with key suppliers and collaborators like Mabworks ⁶. The company relies on certain foreign or foreign-owned third-party vendors, including WuXi and its affiliates, for manufacturing and services ⁶. Unfavorable government policies on international trade, such as export controls, capital controls, or tariffs (e.g., potential 100% tariff on branded or patented drugs imported into the U.S. announced by President Trump ⁶), could increase manufacturing costs, disrupt supply chains, and delay development timelines ⁶.

CLIMB BIO, INC. faces numerous material risks, including significant and expected ongoing losses, with a net loss of $59.9 million ⁴ for the year ended December 31, 2025, and an accumulated deficit of $289.7 million ⁵ as of December 31, 2025, and no current product revenue ⁶. The company's ability to access capital when needed is uncertain, and a failure to secure additional funding could force delays or termination of product development programs ⁶. The success of its product candidates, budoprutug and CLYM116, is dependent on lengthy, complex, and expensive nonclinical and clinical development processes with uncertain outcomes, and preliminary clinical data may not predict final results ⁶. Clinical development in immunology and autoimmune diseases presents inherent challenges, and difficulties in patient enrollment or retention could adversely affect development timelines ⁶. The company operates in a highly competitive environment with rapid technological change, where competitors may achieve regulatory approval sooner or develop superior products ⁶. Estimates of market opportunity and growth forecasts may be inaccurate ⁶. Legal and regulatory risks include potential litigation, which could result in significant costs and divert management attention ⁶. Enacted and future legislation, such as the Inflation Reduction Act of 2022 (IRA), may increase the difficulty and cost of obtaining marketing approval and commercializing products, and could affect pricing, particularly for drugs subject to Medicare price negotiations or inflation-based rebates ⁶. Disruptions in the supply chain or manufacturing, including reliance on single-source suppliers and the complexities of biologics manufacturing, could delay or impair development efforts ⁶. The company relies heavily on in-licensed intellectual property, and failure to obtain, maintain, or enforce adequate patent protection could harm its competitive position ⁶. Geopolitical risks, particularly concerning U.S. and international trade policies with China, including potential restrictions from legislation like the BIOSECURE Act, could disrupt supply chains, increase costs, and limit collaborations with Chinese partners like Mabworks ⁶. Data privacy and security laws, such as GDPR and CCPA, impose stringent requirements, and any actual or perceived failure to comply could lead to regulatory investigations, litigation, fines, and business disruptions ⁶. The company has identified two unremediated material weaknesses in its internal control over financial reporting as of December 31, 2025 ⁶, which could impact the accuracy and timeliness of financial reporting and adversely affect its business and reputation.

Management's message to shareholders emphasizes a commitment to developing potential best-in-class therapeutics for immune-mediated diseases, built upon strategically acquired or in-licensed product candidates with clear biological rationale and well-defined development pathways ⁶. The overall tone is one of cautious optimism regarding the pipeline, particularly budoprutug and CLYM116, while acknowledging the significant financial and operational challenges inherent in clinical-stage biotechnology ⁶. Management explicitly states that the company has incurred significant losses and expects to continue incurring substantial losses for the foreseeable future, with no current source of product revenue ⁶. They project that existing capital resources of $160.7 million ⁷ as of December 31, 2025, will be sufficient to fund operations into 2028 ⁶, though this estimate is based on assumptions that may prove incorrect.

Three strategic priorities are emphasized for the period ahead. First, the company aims to advance budoprutug into late-stage development in pMN, with initial data from the Phase 2 PrisMN trial's low dose cohort, including B cells and anti-PLA2R, anticipated in the second half of 2026 ⁶. Second, management is focused on evaluating budoprutug in ITP and SLE, with initial data from the Phase 1b portion of the ITP trial and the global Phase 1b SLE trial also anticipated in the second half of 2026 ⁶, and first-patient-in for the parallel China SLE trial expected in the first half of 2026 ⁶. Third, the company is accelerating the development of CLYM116, with initial data from the Phase 1 study in healthy volunteers anticipated in mid-2026 ⁶. These priorities underscore a focus on progressing the clinical pipeline and leveraging differentiated mechanisms of action to address unmet medical needs in immune-mediated diseases.