10-K: Climb Bio Reports FY25 Loss, Advances Immune Disease Pipeline

Climb Bio, Inc. reported a net loss of $59.9 million for fiscal year 2025, while actively progressing its lead product candidates, budoprutug and CLYM116, through multiple clinical trials for immune-mediated diseases.

Summary

• Climb Bio, Inc. is a clinical-stage biotechnology company focused on developing therapeutics for immune-mediated diseases.
• The company's lead product candidate, budoprutug, an anti-CD19 monoclonal antibody, is in clinical trials for primary membranous nephropathy (pMN), immune thrombocytopenia (ITP), and systemic lupus erythematosus (SLE).
• CLYM116, a next-generation anti-APRIL monoclonal antibody, is being developed for IgA Nephropathy (IgAN) and other B-cell mediated diseases.
• For the fiscal year ended December 31, 2025, the company reported a net loss of $59.9 million, an improvement from a $73.9 million net loss in 2024.
• The accumulated deficit as of December 31, 2025, was $289.7 million.
• Cash, cash equivalents, and marketable securities totaled $160.7 million as of December 31, 2025, which is estimated to fund operations into 2028.
• Research and development expenses significantly increased to $46.7 million in 2025 from $14.3 million in 2024, primarily due to the advancement of budoprutug clinical trials and the licensing of CLYM116.
• The company is actively enrolling patients in Phase 2 PrisMN trial for budoprutug in pMN, Phase 1b/2a trial for budoprutug in ITP, and a global Phase 1b trial for budoprutug in SLE.
• A parallel Phase 1b clinical trial for budoprutug in SLE patients in China received IND clearance in December 2025, with first-patient-in anticipated in the first half of 2026.
• A Phase 1 clinical trial for a high-concentration subcutaneous (SC) formulation of budoprutug in healthy volunteers in Australia completed dosing in September 2025, with data anticipated in the first half of 2026.
• A Phase 1 clinical trial for CLYM116 in healthy volunteers in Australia was initiated in November 2025, with initial data anticipated in mid-2026.
• The company's partner, Mabworks, initiated a Phase 1/2 clinical trial of CLYM116 in China in December 2025.
• Material weaknesses in internal control over financial reporting were identified, with two remaining unremediated as of December 31, 2025.
• A complaint was filed on December 31, 2025, in Delaware Superior Court against Alumis Inc. and Acelyrin, disputing a milestone payment related to budoprutug.

Sentiment

Score: 6

Explanation: StockSavvy.ai views this as a moderately positive report, reflecting solid clinical progress and a clear strategic direction in a high-potential market, balanced by significant ongoing losses, the inherent risks of drug development, and unremediated internal control weaknesses.

Positives

• Significant progress across multiple clinical trials for budoprutug (pMN, ITP, SLE) and CLYM116 (IgAN), demonstrating active pipeline advancement.
• Encouraging Phase 1b data for budoprutug in pMN, showing 60% complete remission of proteinuria in 3 of 5 patients, complete B-cell depletion, and durable reductions for up to three years, suggesting strong therapeutic potential.
• FDA orphan-drug designation for budoprutug in pMN provides potential market exclusivity and financial incentives, enhancing its commercial prospects.
• Advancement of a high-concentration subcutaneous (SC) formulation of budoprutug offers potential for improved patient convenience and a differentiated commercial profile.
• Successful cell line switch for budoprutug manufacturing resulted in a tenfold increase in productivity and improved scalability, which is crucial for future commercialization.
• The company's cash, cash equivalents, and marketable securities of $160.7 million as of December 31, 2025, are projected to fund operations into 2028, providing a solid financial runway.
• Net loss decreased from $73.9 million in 2024 to $59.9 million in 2025, indicating some improvement in financial performance despite ongoing R&D investments.

Negatives

• The company has incurred significant operating losses since inception, with an accumulated deficit of $289.7 million as of December 31, 2025, and does not expect to generate product revenue for the foreseeable future.
• Two material weaknesses in internal control over financial reporting remain unremediated as of December 31, 2025, which could impact financial reporting accuracy and timeliness.
• The company is involved in a legal dispute with Alumis Inc. and Acelyrin regarding a milestone payment for budoprutug, creating financial and operational uncertainty.
• Reliance on third-party manufacturers and single-source suppliers for product candidates introduces risks of supply chain disruptions, quality control issues, and potential delays.
• Incurred a foreign currency loss of $291 thousand in 2025, indicating exposure to foreign exchange rate fluctuations.

Risks

• Incurred significant losses since inception and expects to continue incurring substantial losses for the foreseeable future, potentially never achieving or sustaining profitability.
• Inability to access capital when needed and on acceptable terms may force delays, reductions, or discontinuations of product candidate development programs or commercialization efforts.
• Future success is dependent on the regulatory approval and commercialization of product candidates; delays or failures could materially harm the business.
• Preliminary, initial, or interim results from clinical trials may change as more data and information become available, potentially leading to material changes in final trial results.
• Nonclinical and clinical development is a lengthy, complex, and expensive process with an uncertain outcome, and product candidates may not demonstrate safety or efficacy in later-stage trials or satisfy regulatory requirements.
• Clinical development in immunology and autoimmune diseases presents inherent challenges, such as disease heterogeneity, variable clinical course, and evolving regulatory expectations, which may delay or impair regulatory approval.
• Difficulties enrolling or retaining patients in clinical trials could delay or adversely affect clinical development activities.
• Significant competition in an environment of rapid technological change; competitors may develop or obtain regulatory approval for products before the company or develop superior products.
• Estimates of market opportunity and forecasts of market growth for product candidates may prove to be inaccurate.
• Involvement in litigation could result in significant costs, divert management attention, and harm the business.
• Enacted and future legislation (e.g., IRA, trade policies) may increase the difficulty and cost of obtaining marketing approval and commercializing product candidates, and may affect pricing.
• Disruptions in the supply chain or manufacturing, including reliance on single-source suppliers and complexities of biologics manufacturing, could delay, prevent, or impair development or commercialization efforts.
• Inability to obtain, maintain, or enforce adequate intellectual property protection, or heavy reliance on in-licensed patents, could harm the competitive position.
• Compromised or interrupted information technology systems or data, or those of third parties upon which the company relies, could lead to regulatory investigations, litigation, fines, business disruptions, and reputational harm.
• Inability to attract or retain key personnel necessary to execute the business strategy.
• The trading price of common stock has been and may continue to be volatile, and purchasers could incur substantial losses.
• Identified material weaknesses in internal control over financial reporting; inability to remediate or identify additional weaknesses could affect accurate and timely financial reporting.
• Product candidates may cause adverse events or undesirable side effects, delaying or preventing regulatory approval, limiting commercial profile, or resulting in significant negative consequences following marketing approval.
• Exposure to product liability lawsuits based on the use of product candidates in clinical testing or after marketing approval and commercialization.
• Disruptions at the FDA and other government agencies from funding cuts, personnel losses, regulatory reform, or government shutdowns could hinder the ability to obtain guidance and secure timely approval of product candidates.
• Changes in and uncertainty surrounding U.S. and international trade policies, particularly with respect to China, may adversely impact business and operating results.
• Patent terms may be inadequate to protect the competitive position on product candidates for an adequate amount of time.
• Changes in patent law could diminish the value of patents, thereby impairing the ability to protect intellectual property.
• Failure to comply with procedural requirements imposed by governmental patent agencies could reduce or eliminate patent protection.
• Third parties may initiate legal proceedings alleging infringement, misappropriation, or violation of intellectual property rights.
• Reliance on third parties requires sharing trade secrets, increasing the possibility of discovery or misappropriation.
• Inability to protect and enforce trademarks and trade names or build name recognition in markets of interest.
• Unfavorable global economic conditions could adversely affect business, financial condition, stock price, and results of operations.
• As an emerging growth company and a smaller reporting company, reduced reporting requirements may make common stock less attractive to investors.
• Inability to maintain adequate insurance coverage.
• Changes in tax laws or regulations that are applied adversely may seriously harm the business.

Future Outlook

The company expects to continue incurring operating losses for the foreseeable future and anticipates that expenses will increase due to advancing product candidates, expanding corporate infrastructure, and potential commercialization costs. Existing capital resources of $160.7 million are projected to fund operations into 2028. The company anticipates sharing data from the Phase 1 SC formulation of budoprutug trial and reporting initial data from the first, low dose cohort of the PrisMN Phase 2 trial in pMN, the Phase 1b portion of the budoprutug in ITP trial, and the Phase 1b clinical trial of budoprutug in SLE in the second half of 2026. Initial data from the Phase 1 study of CLYM116 is expected in mid-2026, and first-patient-in for the parallel Phase 1b clinical trial of budoprutug in SLE patients in China is anticipated in the first half of 2026.

Management Comments

• "We are a clinical-stage biotechnology company committed to developing potential best-in-class therapeutics that address significant unmet need for patients living with immune-mediated diseases."
• "We have built our pipeline by strategically acquiring or in-licensing product candidates that we believe have clear biological rationale, well-defined development pathways, and the potential to address multiple indications."
• "We believe budoprutug may offer a meaningful and potentially durable treatment for patients [with pMN]."
• "Given the chronic nature of many autoimmune diseases, we believe an SC formulation represents an important strategic and commercial differentiator."
• "We believe CLYM116s differentiated sweeper mechanism and potential for favorable PK and potent APRIL and IgA suppression position it for meaningful differentiation from other anti-APRIL and B-cell activating factor (BAFF)/APRIL programs."
• "Business development is a core element of our corporate strategy."
• "We believe our existing cash, cash equivalents and marketable securities of $160.7 million as of December 31, 2025 will be sufficient to fund our operations into 2028."
• "Management has concluded that the material weaknesses in internal control over financial reporting were due to the fact that we were a private company with limited resources when the material weaknesses were identified and did not have the necessary business processes and related internal controls formally designed and implemented, coupled with the appropriate resources with the appropriate level of experience and technical expertise, to oversee our business processes and controls."

Industry Context

StockSavvy.ai notes that Climb Bio operates in the highly competitive and rapidly evolving immunology and inflammation field, characterized by significant R&D investment and a strong emphasis on intellectual property. The company's focus on CD19 and APRIL targets aligns with emerging strategies to address B-cell mediated diseases, building on the success and limitations of earlier anti-CD20 therapies like rituximab. Competitors include major pharmaceutical and biotechnology companies developing similar modalities (e.g., Amgen, Novartis, Bristol Myers Squibb, Otsuka, Vera Therapeutics) as well as CAR-T and bispecific engager therapies, highlighting the need for differentiated efficacy, safety, and convenience. The recent accelerated approval of sibeprenlimab (VOYXACT) by Otsuka for IgAN validates the APRIL pathway, but also intensifies competition for CLYM116, emphasizing the importance of its 'sweeper mechanism' and potential for less frequent dosing.

Comparison to Industry Standards

• Budoprutug (anti-CD19 mAb) in pMN: Phase 1b data showing 60% complete remission of proteinuria in 3 of 5 patients, complete B-cell depletion, and durable reductions for up to three years, suggests a potentially superior or more durable response compared to current immunosuppressive therapies and even anti-CD20 mAbs like rituximab, which often have delayed responses and lower complete remission rates.
• Budoprutug's differentiation: Positioned against Amgen's UPLIZNA (inebilizumab) for NMOSD, IgG4-RD, gMG, and other CD19-targeting therapies including CAR-T (e.g., Novartis AG, Bristol Myers Squibb Company) and bispecific T-cell engagers (e.g., Cullinan Therapeutics, Zenas BioPharma). Budoprutug's low-fucosylated Fc region for enhanced ADCC and high-concentration SC formulation aim to offer a better balance of efficacy, safety, and convenience, potentially avoiding the severe side effects (CRS, ICANS) and logistical complexities of CAR-T therapies.
• CLYM116 (anti-APRIL mAb) differentiation: Competing with other APRIL or BAFF/APRIL inhibitors for IgAN, such as Otsuka's VOYXACT (sibeprenlimab) (FDA accelerated approval), Novartis AG's zigakibart, and Vera Therapeutics, Inc.'s atacicept (BLA submitted). Preclinical studies indicate CLYM116's unique 'sweeper mechanism' with pH-dependent binding, enhanced APRIL clearance, and a 2-3 fold longer half-life compared to sibeprenlimab in NHPs, leading to deeper and more prolonged IgA reduction (over 70% maximal reduction, 50% maintained for three months after single SC dose). This profile aims to address limitations of first-generation inhibitors, such as incomplete APRIL suppression and frequent dosing.
• CLYM116's safety profile: Favorable tolerability in NHP studies with no local tolerance issues or CLYM116-related toxicity findings, and forming fewer high molecular weight complexes compared to sibeprenlimab, potentially suggesting a lower risk of immunogenicity in humans, which could be a significant advantage in chronic treatment settings.

Management Changes

Corporate Governance

Legal Proceedings

• On December 31, 2025, the company filed a complaint in Delaware Superior Court against Alumis Inc. and its wholly owned subsidiary, Acelyrin.
• The dispute concerns the Asset Purchase Agreement, seeking a declaratory judgment that the company's budoprutug drug candidate is not a 'Product' under the agreement, and that the company does not owe a milestone payment sought by Alumis.
• This matter is currently pending, and the company is unable to predict the timeline for resolution or the outcome of this matter.
• The company's financial guidance includes the full potential milestone burden, irrespective of the outcome of this matter.

Related Party Transactions

• The company completed the acquisition of Tenet Medicines, Inc. on June 27, 2024, which was majority-owned by funds affiliated with RA Capital Management L.P. prior to the closing.
• Immediately following the acquisition, the company issued 31,238,282 shares of its common stock in a private placement to several accredited institutional investors, including funds affiliated with RA Capital Management, L.P.
• On December 11, 2025, the company entered into an Exchange Agreement with RA Capital Management L.P. and an affiliated entity (the Exchanging Holder), where the Exchanging Holder exchanged 20,440,000 shares of common stock for a pre-funded warrant to purchase the same number of shares.
• RA Capital Management and its affiliates beneficially own approximately 24% of the company's outstanding common stock and have the right to exercise pre-funded warrants to purchase up to 33.0% of common stock.
• RA Capital and the Exchanging Holder have agreed to vote all securities beneficially owned by them or their respective affiliates in excess of 33.0% of the total voting power in proportion to and in accordance with the vote of all other stockholders.
• The company had a service agreement with Sera Services, Inc., a wholly-owned subsidiary of Sera Medicines, LLC, which is controlled by RA Capital Management. Dr. Stephen Thomas, a company board member, owns a minority interest and is a board member of Sera Medicines. The company paid $0.1 million to Sera Services in 2024, and the agreement was terminated in March 2026.
• The company had a service agreement with Blackbird Clinical, Inc., an entity controlled by RA Capital Management, for consulting services. The company paid approximately $0.1 million to Blackbird in 2024, and the agreement was terminated in October 2024.

Stakeholder Impact

• Shareholders: Potential for dilution from future capital raises, volatility in stock price, impact of legal proceedings on share value, and influence of concentrated ownership by RA Capital Management. Capital appreciation is the sole source of gain due to no anticipated dividends.
• Employees: Opportunities for professional growth and development, competitive compensation, benefits, and equity incentives. The ability to attract and retain key personnel is critical for business success.
• Customers (future patients): Potential for new, best-in-class therapeutic options for unmet needs in immune-mediated diseases, including more convenient subcutaneous formulations.
• Suppliers/CDMOs: Continued reliance on third-party manufacturers and single-source suppliers, with associated risks of supply chain disruptions, quality issues, and compliance failures.
• Creditors: Impact of ongoing operating losses and the need for future financing on the company's creditworthiness.

Next Steps

• Report data from the Phase 1 clinical trial of the subcutaneous (SC) formulation of budoprutug in healthy volunteers in the first half of 2026.
• Report initial data from the first, low dose cohort of the Phase 2 PrisMN trial in pMN in the second half of 2026.
• Report initial data from the Phase 1b portion of the budoprutug in ITP trial in the second half of 2026.
• Report initial data from the Phase 1b clinical trial of budoprutug in SLE in the second half of 2026.
• Achieve first-patient-in (FPI) in the parallel Phase 1b clinical trial of budoprutug in SLE patients in China in the first half of 2026.
• Report initial data from the Phase 1 study of CLYM116 in mid-2026.
• Advance budoprutug into late-stage development in pMN, including identifying a dose for Phase 3 clinical development.
• Expand budoprutug into additional B-cell mediated diseases based on data from ongoing pMN, ITP, and SLE clinical trials and external data.
• Explore opportunities to expand the pipeline through business development, prioritizing immune-mediated diseases and nephrology.
• Remediate identified material weaknesses in internal control over financial reporting.
• Continue to pursue regulatory clearance to open additional trial sites outside the U.S. for the PrisMN trial.
• Mabworks, the company's partner, will continue its Phase 1/2 clinical trial of CLYM116 in China.

Key Dates

Recommendation

Climb Bio demonstrates promising clinical progress with its lead candidates, budoprutug and CLYM116, targeting significant unmet needs in immune-mediated diseases. The positive Phase 1b data for budoprutug in pMN and the strategic advancement of a subcutaneous formulation are notable. However, the company faces substantial financial challenges, including recurring losses and a significant accumulated deficit, necessitating future capital raises that could dilute existing shareholders. The ongoing legal dispute over a milestone payment and unremediated material weaknesses in internal controls introduce additional uncertainty. While the long-term potential is present, the early stage of development, competitive landscape, and operational risks warrant a cautious 'Hold' recommendation for seasoned investors, awaiting further de-risking through later-stage clinical data and resolution of internal control issues.

Keywords

Biotechnology, Clinical-stage, Immune-mediated diseases, Autoimmune disorders, Monoclonal antibody, CD19, APRIL, Budoprutug, CLYM116, Primary membranous nephropathy, pMN, Immune thrombocytopenia, ITP, Systemic lupus erythematosus, SLE, IgA Nephropathy, IgAN, Drug development, Clinical trials, Regulatory approval, SEC filing, 10-K, Financial reporting, Corporate governance, Risk management, Intellectual property, Pharmaceutical, Therapeutics