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Third Arc Bio builds antibodies that link the immune system's T cells to cancer cells. Its first medicine, aimed at tumours carrying the protein Claudin 6, entered its first human trial in 2025.
Third Arc Bio was launched in 2022 with seed funding from Omega Funds and came into public view on 23 July 2024 with an oversubscribed USD 165 million Series A led by Vida Ventures and co-led by Cormorant Asset Management and Hillhouse Investment, under chief executive Peter Lebowitz, formerly head of oncology R&D at Johnson & Johnson. It designs multifunctional antibodies optimised for T cell engagement in solid tumours (its ARCStim platform) and in immunology and inflammation (ARCTag). The lead asset ARC101, a bispecific T cell engager against Claudin 6 (CLDN6), dosed its first patient in a phase 1 dose-escalation trial in CLDN6-expressing advanced solid tumours in March 2025. In November 2025 Adagene licensed it two masked CD3 T cell engagers built on its SAFEbody technology, and on 4 February 2026 the company added a USD 52 million Series A extension led by a16z with Omega Funds.
| Round | Year | Amount | Source |
|---|---|---|---|
| Series A extension · Led by a16z with founding investor Omega Funds | 2026 | $52M | thirdarcbio.com |
| Series A · Led by Vida Ventures, co-led by Cormorant Asset Management and Hillhouse Investment | 2024 | $165M | biospace.com |
Amounts only where the cited source states them. Rounds without a public source are not listed.
Shares Omega Funds, Vida Ventures, Cormorant Asset Management.
Shares Logos Capital, Cormorant Asset Management.
Shares Logos Capital, Foresite Capital.
Shares CD3, Bispecific antibodies, T-cell engagers (bispecific).
Shares CD3, Bispecific antibodies, T-cell engagers (bispecific).
Shares Logos Capital, Foresite Capital, Cormorant Asset Management.
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