The program is initially being developed in combination with JANX007, with the goal of further enhancing the durability of anti-tumor immune responses through tumor-restricted CD28 co-stimulation. Over time, Janux intends to evaluate JANX013 in combination with additional candidates within its prostate cancer portfolio.

Prostate cancer is the most commonly diagnosed cancer in men, excluding skin cancers. Clinical experience with Janux's PSMA-targeted T cell engager candidates has demonstrated the potential of tumor-activated T cell immunotherapy in patients with metastatic castration-resistant prostate cancer. CD28 is a key co-stimulatory receptor involved in T-cell activation, expansion, and persistence. JANX013 is designed to selectively deliver CD28 co-stimulation within the tumor microenvironment using Janux’s proprietary tumor-activation technology, with the goal of further enhancing the durability of anti-tumor immune responses while minimizing systemic CD28 activation.

"Co-stimulation plays a critical role in promoting sustained T-cell function and persistence," said Simon Butikofer, M.D., Vice President, Clinical Development. "JANX013 is designed to selectively deliver tumor-restricted co-stimulation in combination with our CD3 T cell engagers, with the goal of extending the durability of anti-tumor immune responses."

"The initiation of the JANX013 clinical program represents an important milestone in the continued evolution of our prostate cancer franchise," said David Campbell, Ph.D., President and Chief Executive Officer of Janux Therapeutics. "By combining complementary tumor-activated immunotherapies, we believe we have an opportunity to further improve long-term outcomes for patients with prostate cancer."

The Phase 1 clinical trial (NCT07813637) is a first-in-human, open-label, multicenter study designed to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary efficacy of JANX013 in combination with JANX007 in adult patients with mCRPC. In addition to evaluating safety, the study is intended to evaluate biomarkers of immune activation, including T-cell expansion and persistence, to characterize the effects of tumor-restricted CD28 co-stimulation and inform future clinical development of JANX013.