8-K: Zenas BioPharma's Obexelimab Shines in MS Trial

Zenas BioPharma announced positive Phase 2 MoonStone trial results for obexelimab in relapsing multiple sclerosis, showing a 95% reduction in new lesions.

Summary

• Positive results from the Phase 2 MoonStone trial of obexelimab in Relapsing Multiple Sclerosis (RMS) were announced.
• Obexelimab met the primary endpoint, demonstrating a statistically significant 95% relative reduction in the cumulative number of new gadolinium (Gd)-enhancing T1 hyperintense lesions over week 8 and week 12 compared with placebo (p=0.0009).
• The adjusted mean number of new GdE T1 hyperintense lesions per scan in the obexelimab group was 0.01 (95% CI: 0.00, 0.06) compared to 0.23 (95% CI: 0.11, 0.51) with placebo.
• Obexelimab significantly reduced the cumulative number of new and/or enlarging T2 weighted hyperintense lesions compared to placebo.
• The safety profile of obexelimab was consistent with that observed in prior completed trials, including cases of infections and hypersensitivity, most commonly mild injection site reactions.
• Expect to report 24-week data from the MoonStone trial in the first quarter of 2026.
• Expect topline results from the obexelimab Phase 3 INDIGO trial in IgG4-RD around year-end 2025.
• Expect topline results from the Phase 2 SunStone trial in Systemic Lupus Erythematosus in mid-2026.
• Orelabrutinib, a highly-selective central nervous system-penetrant, oral, small molecule Bruton's Tyrosine Kinase (BTK) inhibitor, is now being studied in a global Phase 3 clinical trial in patients with Primary Progressive Multiple Sclerosis (PPMS).
• Expect to initiate a global Phase 3 trial of orelabrutinib in patients with Secondary Progressive Multiple Sclerosis (SPMS) in the first quarter of 2026.

Sentiment

Score: 9

Explanation: The filing reports highly statistically significant positive Phase 2 clinical trial results for a key pipeline asset (obexelimab in RMS), demonstrating near-complete suppression of active inflammation markers. This strong efficacy, combined with a consistent safety profile and the broad potential across multiple autoimmune diseases, is a significant positive for the company's development pipeline and future prospects. The advancement of another key asset, orelabrutinib, into Phase 3 trials further strengthens the positive outlook.

Positives

• Obexelimab achieved a highly statistically significant 95% relative reduction in new Gd-enhancing T1 hyperintense lesions in RMS patients (p=0.0009).
• Near-complete suppression of new GdE T1 hyperintense lesions was observed by 8 weeks of treatment and sustained through week 12.
• Obexelimab significantly reduced the cumulative number of new and/or enlarging T2 weighted hyperintense lesions, indicating a reduction in disease burden.
• The safety profile of obexelimab was consistent with prior trials, suggesting good tolerability.
• The results validate obexelimab's potential as a meaningful therapy across multiple autoimmune diseases, including Immunoglobulin G4-Related Disease (IgG4-RD) and Systemic Lupus Erythematosus (SLE).
• The unique inhibitory mechanism of action, subcutaneous self-administration, and tolerability profile position obexelimab as a potential broad treatment for B cell-mediated autoimmune diseases.
• Advancement of orelabrutinib into a global Phase 3 trial for PPMS and planned initiation for SPMS expands the company's late-stage pipeline.

Risks

• Limited operating history and anticipation of incurring substantial and increasing losses for the foreseeable future.
• Need for substantial additional financing to achieve goals.
• Uncertainty, length, and expense of clinical development, with risks of additional costs, delays, or failure to complete development and commercialization of current or future product candidates.
• Delays or difficulties in the enrollment and dosing of patients in clinical trials.
• Impact of any significant adverse events or undesirable side effects caused by product candidates.
• Potential competition from large and specialty pharmaceutical and biotechnology companies, many of which already have approved therapies in current indications.
• Ability to realize the benefits of current or future collaborations or licensing arrangements and successfully consummate future partnerships.
• Ability to obtain regulatory approval to commercialize any product candidate in the United States or any other jurisdiction, and the risk that data may be insufficient or approval may be for a narrower indication.
• Dependence on the services of senior management and other clinical and scientific personnel, and the ability to retain these individuals or recruit additional personnel.
• Ability to grow the organization and manage the growth and expansion of operations.
• Risks related to the complex manufacturing of product candidates and potential difficulties encountered by third-party manufacturers.
• Ability to obtain and maintain sufficient intellectual property protection for product candidates.
• Reliance on third parties to conduct preclinical studies and clinical trials.
• Compliance with obligations under licenses granted by others for the rights to develop and commercialize product candidates.
• Significant political, trade, and regulatory developments, including changes in relations between the U.S. and China.
• Risks related to the operations of suppliers, many located outside of the United States, including the current sole contract manufacturing organization for drug substance and drug product, WuXi Biologics (Hong Kong) Limited, which is located in China.

Future Outlook

Zenas BioPharma expects to report 24-week data from the MoonStone trial in the first quarter of 2026, which will include additional secondary and exploratory endpoints to inform obexelimab's potential impact on disability progression and future development in RMS. The company also anticipates topline results from the obexelimab Phase 3 INDIGO trial in IgG4-RD around year-end 2025 and from the Phase 2 SunStone trial in Systemic Lupus Erythematosus in mid-2026. Furthermore, a global Phase 3 clinical trial for orelabrutinib in Primary Progressive Multiple Sclerosis is underway, with plans to initiate another global Phase 3 trial for orelabrutinib in Secondary Progressive Multiple Sclerosis in the first quarter of 2026.

Management Comments

• "These profound MoonStone trial results, including the near elimination of new GdE T1 lesions, provide strong evidence of the deep and sustained inhibitory mechanism of obexelimab and further validate the potential for obexelimab to become a meaningful therapy across multiple autoimmune diseases, including Immunoglobulin G4-Related Disease and Systemic Lupus Erythematosus, which are currently being evaluated by Zenas in Phase 3 and Phase 2 clinical trials." Lonnie Moulder, Founder and Chief Executive Officer of Zenas.
• "The observed clinical activity in the MoonStone trial, combined with obexelimab's unique inhibitory mechanism of action, subcutaneous self-administration and tolerability profile, position obexelimab as a potential option to broadly address the pathogenic role of B cells in autoimmune diseases." Lisa von Moltke, M.D., Head of Research and Development and Chief Medical Officer of Zenas.
• "With these highly statistically significant data, we look forward to reporting 24-week data in the first quarter of 2026, which will include additional secondary and exploratory endpoints that may inform obexelimab's potential impact on disability progression and help us determine next steps for future development of obexelimab in relapsing MS." Lisa von Moltke, M.D., Head of Research and Development and Chief Medical Officer of Zenas.

Industry Context

Multiple Sclerosis (MS) is a chronic, autoimmune disorder affecting approximately 2.9 million people worldwide, primarily females, and is the leading cause of non-traumatic neurological disability in young adults. The disease involves immune system attacks on myelin, leading to inflammation, demyelination, and axonal injury, resulting in diverse clinical manifestations and progressive neurodegeneration. Relapsing Multiple Sclerosis (RMS) is the most common initial diagnosis, and there is a significant unmet need for effective therapies, particularly for non-relapsing Secondary Progressive Multiple Sclerosis (SPMS) and Primary Progressive Multiple Sclerosis (PPMS), where only one approved therapy exists for PPMS. Obexelimab's mechanism of inhibiting B cell activity without depleting them, and orelabrutinib's CNS-penetrant BTK inhibition, aim to address the pathogenic role of B cells and compartmentalized inflammation in MS, aligning with the industry's objective of early intervention with highly effective therapies to slow disability progression.

Comparison to Industry Standards

• The Phase 2 MoonStone trial utilized magnetic resonance imaging (MRI) endpoints that have historically been highly predictive of successful outcomes in large, randomized trials using an annualized relapse rate endpoint in an RMS study population.

Stakeholder Impact

• Shareholders: Highly positive news, likely to increase investor confidence and potentially share price due to strong clinical data for a key pipeline asset.
• Patients (RMS): Offers hope for a new, highly effective treatment option with a favorable safety profile and convenient subcutaneous administration.
• Employees: Positive validation of research and development efforts, potentially boosting morale and attracting talent.
• Regulatory Authorities: Strong data could facilitate future regulatory submissions and approvals.

Next Steps

• Report 24-week data from the MoonStone trial in the first quarter of 2026.
• Report topline results from the obexelimab Phase 3 INDIGO trial in IgG4-RD around year-end 2025.
• Report topline results from the Phase 2 SunStone trial in Systemic Lupus Erythematosus in mid-2026.
• Continue global Phase 3 clinical trial of orelabrutinib in Primary Progressive Multiple Sclerosis (PPMS).
• Initiate a global Phase 3 trial of orelabrutinib in Secondary Progressive Multiple Sclerosis (SPMS) in the first quarter of 2026.

Key Dates

Recommendation

The highly statistically significant positive Phase 2 results for obexelimab in relapsing multiple sclerosis, demonstrating a 95% reduction in new lesions, represent a major de-risking event for a key pipeline asset. This strong efficacy, coupled with a consistent safety profile and the potential for broad application across multiple autoimmune diseases, significantly enhances the company's valuation proposition. The ongoing and planned Phase 3 trials for orelabrutinib further strengthen the long-term growth outlook. While the company acknowledges a need for future financing, the robust clinical data provides a strong foundation for attracting capital. This filing indicates substantial progress and increased probability of commercial success, making it a strong buy for investors seeking exposure to innovative autoimmune disease therapies.

Keywords

Zenas BioPharma, obexelimab, relapsing multiple sclerosis, RMS, autoimmune disease, clinical trial, Phase 2, biopharmaceutical, orelabrutinib, BTK inhibitor, IgG4-RD, Systemic Lupus Erythematosus, SLE, Primary Progressive Multiple Sclerosis, PPMS, Secondary Progressive Multiple Sclerosis, SPMS, neurology, immunology