Third Arc Bio, Inc.

Based in Pennsylvania, US, and founded in 2021 by Sanjaya Singh, Third Arc Bio, Inc. is a biotech company that focuses on developing multifunctional antibodies that are optimized for best-in-class T cell engagement across solid tumors and inflammatory and immunology diseases. In February 2026, Third Arc Bio, Inc. raised USD 52 million in series A funding led by new investor Andreessen Horowitz, with participation from other new investor Galapagos NV.

Returning investors Goldman Sachs Asset Management, BVF Partners, T. Rowe Price Associates, Janus Henderson Investors, Marshall Wace, Foresite Capital, Logos Capital, Freepoint Capital Group, and AbbVie Ventures, Omega Funds, Vida Ventures, Cormorant Asset Management, Hillhouse Investment, and Alderline Group also participated in the round. The round was a part of larger USD 217 million series A funding. As of 2026 the company is headed by its CEO Peter F.

Lebowitz. Third Arc Bio specializes in the development of multifunctional antibodies designed to create immune synapses that precisely activate or inhibit T cells. The company's therapies are targeted at treating solid tumors and inflammatory and immunological (I&I) diseases. Through its expertise in immunology and antibody engineering, Third Arc Bio aims to advance next-generation biologic treatments that could redefine the standard of care in these therapeutic areas.

The company’s solutions are focused on enhancing the immune response to treat complex diseases by optimizing T cell activity, offering a potential breakthrough in the treatment of challenging conditions. The company will use the February 2026 funding to expand its oncology, immunology and inflammation drug portfolio and advance existing drug candidates into early clinical studies.