Third Arc Bio Announces First Patient Dosed in Phase 1 Clinical Trial of Lead T Cell Engager ARC101 to Treat CLDN6 Positive Cancers

-- ARC101 is the company's first bispecific antibody targeting Claudin 6 (CLDN6), optimized for best-in-class T cell engagement

-- First-in-human study will evaluate the safety, tolerability, pharmacokinetics and antitumor activity of ARC101 in patients with advanced cancer

SPRING HOUSE, Pa., March 13, 2025 /PRNewswire/ -- Third Arc Bio Inc., a clinical stage biotech company developing novel multifunctional antibodies for a range of oncology and immunology & inflammation (I&I) indications, today announced the first patient has been dosed in its first-in-human study evaluating ARC101, a potential best-in-class T cell engager targeting Claudin 6 (CLDN6).

This Phase 1 study will evaluate the optimal dosing, safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD) and preliminary antitumor efficacy of ARC101 as monotherapy in patients with locally advanced or metastatic solid tumors expressing CLDN6.

"ARC101 is the first program from our growing pipeline to reach the clinic – signifying Third Arc Bio's transition into a clinical stage company," said Peter F. Lebowitz, MD, PhD, Chief Executive Officer and Chief Medical Officer of Third Arc Bio. "Given ARC101's remarkable specificity for CLDN6 over other Claudin proteins, we believe ARC101 has the potential to achieve a superior therapeutic index in the clinic. As we advance the ARC101 clinical program, we are also rapidly progressing our next programs towards the clinic with the execution of critical IND-enabling studies."

ARC101 represents the company's first clinical effort to evaluate in humans its immune cell engaging antibodies that modulate the immune system in precise ways to target specific disease states. Building upon ARC101 as a foundation, Third Arc Bio continues to invest in its Synergy Platform to develop a pipeline of novel CD3 and CD28 targeting multispecifics to create transformational drugs against solid tumors.

Third Arc Bio will present a poster highlighting preclinical results for ARC101 at the upcoming 2025 American Association for Cancer Research (AACR) Annual Meeting. The data will highlight ARC101's best-in-class specificity for CLDN6 versus other closely related Claudin proteins.  

About Third Arc Bio
Third Arc Bio is a clinical stage biotech company developing multifunctional antibodies that generate immune synapses to precisely activate or inhibit T cells. The company's drug development engine delivers superior biologics optimized to create best-in-class T cell engagement by leveraging novel technologies that power a pipeline of high value therapeutics. The Third Arc Bio platforms include a solid tumor Synergy Platform and an immunology & inflammation (I&I) Tethering Platform that offers precision immune regulation to achieve superior efficacy and safety. To learn more, visit www.thirdarcbio.com.

About ARC101
ARC101 is a potential best-in-class T cell engager that targets solid tumors expressing CLDN6. ARC101 exhibits high specificity with no off-target binding, avoids other Claudin family proteins, and has potent cytotoxicity, a long half-life and optimal biophysical properties. ARC101 is currently in Phase 1 studies (NCT06672185) to assess its safety, tolerability, pharmacokinetics and antitumor activity in patients with advanced cancer.

Media Contact
Peg Rusconi, Deerfield Group
[email protected]

SOURCE Third Arc Bio