Zenas secures $200M Series C for lead monoclonal antibody milestones

Zenas BioPharma has secured $200 million in a series C funding round, extending its financial runway by 18 months and supporting several key readouts for its leading monoclonal antibody, obexelimab. This financing round, notably Zenas' second significant capital infusion in succession, was led by SR One, New Enterprise Associates, Norwest Venture Partners, and Delos Capital.

The primary allocation of these funds will be directed towards advancing mid- to late-stage clinical trials for obexelimab, which is being developed to treat various autoimmune diseases. Lonnie Moulder, founder and CEO of Zenas, explained that the decision to remain private stemmed partly from an unfavorable IPO environment at the onset of fundraising. Moulder highlighted the challenging market conditions for potential IPOs in their sector, despite a brief surge of public offerings in January.

The newly raised capital will enable Zenas to further the clinical development of obexelimab, a dual-acting antibody that targets CD19 and FcγRIIb. Zenas acquired this asset from Xencor and has projected four phase 2 or phase 3 trial readouts by 2026. High on their agenda is a phase 3 trial for patients with IgG4-related diseases, with data expected by late 2025.

Obexelimab was previously a focus for Xencor until a disappointing lupus trial in 2018 led the company to abandon plans for a phase 3 study in another indication and seek a partner. Zenas acquired the asset more than three years later, obtaining it in exchange for equity and milestone commitments. Bristol Myers Squibb has also shown interest, providing Zenas with $50 million upfront in September 2023 for certain rights in Asia.

Zenas is gearing up to launch two phase 2 trials this summer, targeting patients with multiple sclerosis (MS) and systemic lupus erythematosus (SLE). Moulder stated that both studies are expected to conclude before the IgG4-related diseases study, with the MS trial anticipated to report results first. This capital infusion will support the completion of these trials ahead of the phase 3 readout.

Additionally, Zenas is looking forward to a phase 2 readout for warm autoimmune hemolytic anemia by the end of the year. The company is also exploring partnerships for two of its earlier-stage assets: an anti-TNFα therapy named ZB002 and a TLA4-Ig fusion protein called ZB004. Moulder, who also co-founded the cancer-focused biotech Tesaro (later acquired by GSK), is navigating these developments.

Autoimmune diseases like MS and lupus have attracted considerable interest from biotech companies, especially those pivoting from oncology to autoimmune conditions. Moulder believes that obexelimab, which inhibits rather than depletes B cells, could offer better tolerability compared to other therapies.

Founded in 2021, Zenas initially described itself as a "cross-border" company with operations in both China and the U.S. However, the company has since evolved into what Moulder now calls a "global company," with a significant presence in the Boston area. This evolution reflects Zenas' growth and adaptation, which might not be apparent since the company is not publicly traded.