Zenas secures $200M for pivotal obexelimab immunology trials

Zenas BioPharma has successfully secured $200 million in an expanded series C financing round, which will be pivotal in advancing its key asset, obexelimab, through various mid- and late-stage clinical trials targeting an array of autoimmune disorders. CEO Lonnie Moulder expressed, "This financing enables us to complete multiple potentially value-driving clinical programmes."

This latest fundraising effort follows Zenas' $118-million series B round in 2022. The primary focus of the new funds will be the development of obexelimab, a bifunctional monoclonal antibody that targets B-cells, plasmablasts, and CD19-expressing plasma cells implicated in autoimmune conditions.

Leading the development pipeline is the ongoing Phase III INDIGO trial, which began last year to evaluate obexelimab in patients suffering from IgG4-related disease (IgG4-RD). According to a mid-stage study published last August in The Lancet Rheumatology, obexelimab demonstrated "rapid, strong, and sustained" improvements, achieving complete remission in many patients with active IgG4-RD. "Obexelimab's mechanism of action and chronic dosing regimen may broadly and effectively address the pathogenic role of B-cell lineage in chronic autoimmune disease and has the potential to show greater clinical benefits, including over a longer course of maintenance treatment," Moulder told FirstWord.

Zenas also has plans to initiate Phase II studies in multiple sclerosis and systemic lupus erythematosus within the next several months. Additionally, the company is conducting a Phase II/III trial named SApHiAre for warm autoimmune haemolytic anaemia. Initial results from the INDIGO trial are anticipated by the end of 2025, while preliminary findings from the SApHiAre trial are expected by the end of this year.

In a significant development last year, Bristol Myers Squibb secured licensing rights for the experimental bifunctional antibody in various regions including Japan, South Korea, Taiwan, Singapore, Hong Kong, and Australia. This agreement included a $50-million upfront payment and an undisclosed equity investment. Obexelimab was initially developed by Xencor before Zenas obtained global rights to the drug in 2021 for up to $480 million.

Beyond obexelimab, Zenas is progressing with other candidates in its autoimmune pipeline. This includes an anti-TNFα antibody, ZB002, which is currently in Phase I trials, and a preclinical CTLA4-Ig fusion protein named ZB004. "We are considering partnership and collaboration opportunities for these two programmes," Moulder said.

The series C financing round was co-led by SR One, NEA, Norwest Venture Partners, and Delos Capital. It also saw participation from Enavate Sciences and Longitude Capital, along with new investors like the Federated Hermes Kaufmann Funds and Arrowmark Partners. Existing backers such as Fairmount, Wellington Management, Rock Springs Capital, and Vivo Capital continued their support.

This substantial influx of capital will enable Zenas BioPharma to effectively advance its clinical programs, positioning obexelimab as a potential breakthrough in the treatment of multiple autoimmune diseases.