Zenas Biopharma Highlights Results From Phase 2 MoonStone Trial Of Obexelimab In RMS In Late-Breaking Oral Presentation At ACTRIMS Forum 2026

- Obexelimab met the primary endpoint with a 95% relative reduction in new gadolinium (Gd)-enhancing T1 lesions compared with placebo over weeks 8 and 12 (p=0.0009) -

- Separately announced 24-week data support the robust and durable activity of obexelimab and further validate its unique inhibitory mechanism of action -

- Obexelimab was well tolerated, and no new safety signals were observed -

WALTHAM, Mass., Feb. 09, 2026 (GLOBE NEWSWIRE) -- Zenas BioPharma, Inc. ("Zenas," "Zenas BioPharma" or the "Company") (NASDAQ:ZBIO), a clinical-stage global biopharmaceutical company committed to being a leader in the development and commercialization of transformative therapies for patients living with autoimmune diseases, today announced that results from the Phase 2 MoonStone trial of obexelimab in Relapsing Multiple Sclerosis (RMS) were presented in a late-breaking oral presentation at the Americas Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS) Forum 2026, which took place from February 5-7, 2026 in San Diego, California.

Obexelimab met the primary endpoint, demonstrating a highly statistically significant 95% relative reduction in the cumulative number of new gadolinium (Gd)-enhancing (GdE) T1 hyperintense lesions over week 8 and week 12 compared with placebo (p=0.0009). Near-complete suppression of new GdE T1 hyperintense lesions, markers of active inflammation, was observed with obexelimab by 8 weeks of treatment and was sustained through week 12. The adjusted mean number of new GdE T1 hyperintense lesions per scan was 0.01 (95% CI: 0.00, 0.06) in the obexelimab group compared to 0.23 (95% CI: 0.11, 0.51) with placebo. Over weeks 8 and 12, only two new GdE T1 lesions were observed in obexelimab-treated patients compared to 19 in placebo-treated patients, with 97.2% of obexelimab treated patients free from T1 lesions over this period. Consistent with the inhibitory mechanism of obexelimab, mean B cell values remained within the normal range for obexelimab-treated patients. 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.

Separately announced 24-week data further confirm the robust and durable activity of obexelimab. The highly statistically significant reductions in total GdE T1 lesions observed with obexelimab over weeks 8 and 12 were maintained through week 24; unadjusted means were 0.87 at baseline, 0.08 at week 12 and 0.04 at week 24 for obexelimab indicating a 95% reduction. Obexelimab meaningfully reduced serum Neurofilament Light (NfL) by 40% through week 24; 15.28 pg/mL at baseline declining to 12.7 pg/mL at week 12 and 9.2 pg/mL at week 24. New and/or enlarging T2 lesions were also lower in the obexelimab arm and the Expanded Disability Status Scale (EDSS) scores were stable, indicating a lack of progression in physical disability. No new safety signals were observed at week 24.

The ongoing open-label expansion portion of the Phase 2 MoonStone trial continues to follow patients for longer-term outcomes. Within Multiple Sclerosis, Zenas is currently advancing orelabrutinib, a potentially best-in-class, highly selective central nervous system (CNS)-penetrant, oral, small molecule Bruton's Tyrosine Kinase (BTK) inhibitor. Orelabrutinib is being studied in a global Phase 3 clinical trial in patients with Primary Progressive Multiple Sclerosis (PPMS). Zenas also expects to initiate a global Phase 3 trial of orelabrutinib in patients with non-active Secondary Progressive Multiple Sclerosis (naSPMS) in this quarter.