Third Arc Bio, a clinical-stage biotechnology company developing novel multifunctional antibodies, has closed a startup funding round, raising USD 52 million through a Series A extension. The financing, which adds to a previously announced USD 165 million Series A round, positions the Spring House, Pennsylvania-based company to accelerate its oncology and immunology & inflammation (I&I) drug development programs.
The startup funding round was led by new investor Andreessen Horowitz (a16z), with participation from a syndicate of investors including: Omega Funds (founding investor), Life Sciences at Goldman Sachs Alternatives, BVF Partners LP, funds managed by abrdn. Inc., T. Rowe Price Associates, Inc., Marshall Wace, Hillhouse Investment, Galapagos NV, AbbVie Ventures, Alderline Group.
Third Arc Bio is moving to advance innovative drug development platforms led by ARC101, a bispecific T cell engager currently in Phase I clinical trials targeting CLDN6-expressing solid tumors. The firm’s scientific approach centers on two key platforms: ARCStim Platform (Solid Tumors), and ARCTag Platform (I&I). These platforms leverage multispecific antibodies to generate precise immune synapses, potentially offering enhanced therapeutic efficacy and safety compared to conventional treatments.
Jorge Conde, General Partner at a16z and new member of Third Arc Bio’s Board of Directors, emphasized the company’s unique approach: “Third Arc represents a shift toward more precise immune modulation—moving beyond systemic exposure to therapies designed to deliver highly controlled biological effects at sites of disease.”