{"entity":{"id":"third-arc-bio","kind":"company","name":"Third Arc Bio","aka":[],"tldr":"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.","summary":"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.","asOf":"2026-10-29","links":[{"label":"Official website","url":"https://www.thirdarcbio.com/"},{"label":"Launch and USD 165 million Series A, July 2024","url":"https://www.biospace.com/third-arc-bio-launches-with-oversubscribed-165-million-series-a-financing-to-deliver-superior-biologics-for-solid-tumors-and-inflammatory-immunology-i-i-diseases"},{"label":"First patient dosed with ARC101, March 2025","url":"https://www.thirdarcbio.com/news/third-arc-bio-announces-first-patient-dosed-in-phase-1-clinical-trial-of-lead-t-cell-engager-arc101-to-treat-cldn6-positive-cancers/"},{"label":"USD 52 million Series A extension, February 2026","url":"https://www.thirdarcbio.com/news/third-arc-bio-announces-$52m-series-a-extension-to-expand-oncology-and-immunology-&-inflammation-portfolio/"}],"tags":[],"related":[],"cancers":[],"sections":["immunotherapy"],"technologies":["t-cell-engager","bispecific-antibody"],"targets":["cldn6","cd3"],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":["The phase 1 trial of ARC101 is registered as NCT06672185 per the company's March 2025 release; that trial has no record in the corpus, so it is not linked. Headquarters follows the dateline of the company's 2025 and 2026 releases; the 2024 launch release was datelined Boston."],"hq":"Spring House, PA","country":"US","companyType":"biotech","website":"https://www.thirdarcbio.com/","founded":2022,"stage":"startup","investors":["vida-ventures","cormorant-asset-management","omega-funds","foresite-capital","logos-capital","abbvie-ventures","a16z-bio-health"],"funding":[{"round":"Series A","year":2024,"amountUsd":165000000,"source":"https://www.biospace.com/third-arc-bio-launches-with-oversubscribed-165-million-series-a-financing-to-deliver-superior-biologics-for-solid-tumors-and-inflammatory-immunology-i-i-diseases","note":"Led by Vida Ventures, co-led by Cormorant Asset Management and Hillhouse Investment"},{"round":"Series A extension","year":2026,"amountUsd":52000000,"source":"https://www.thirdarcbio.com/news/third-arc-bio-announces-$52m-series-a-extension-to-expand-oncology-and-immunology-&-inflammation-portfolio/","note":"Led by a16z with founding investor Omega Funds"}]},"route":"/companies/third-arc-bio/","neighbours":{"section":[{"id":"immunotherapy","kind":"section","name":"Immunotherapy","route":"/fronts/immunotherapy/"}],"technology":[{"id":"bispecific-antibody","kind":"technology","name":"Bispecific antibodies","route":"/technologies/bispecific-antibody/"},{"id":"t-cell-engager","kind":"technology","name":"T-cell engagers (bispecific)","route":"/technologies/t-cell-engager/"}],"target":[{"id":"cd3","kind":"target","name":"CD3","route":"/targets/cd3/"},{"id":"cldn6","kind":"target","name":"Claudin 6","route":"/targets/cldn6/"}],"company":[{"id":"abbvie-ventures","kind":"company","name":"AbbVie Ventures","route":"/companies/abbvie-ventures/"},{"id":"a16z-bio-health","kind":"company","name":"Andreessen Horowitz Bio + Health","route":"/companies/a16z-bio-health/"},{"id":"cormorant-asset-management","kind":"company","name":"Cormorant Asset Management","route":"/companies/cormorant-asset-management/"},{"id":"foresite-capital","kind":"company","name":"Foresite Capital","route":"/companies/foresite-capital/"},{"id":"logos-capital","kind":"company","name":"Logos Capital","route":"/companies/logos-capital/"},{"id":"omega-funds","kind":"company","name":"Omega Funds","route":"/companies/omega-funds/"},{"id":"vida-ventures","kind":"company","name":"Vida Ventures","route":"/companies/vida-ventures/"}]}}