Janux doses first patient in Phase 1 trial of prostate cancer immunotherapy JANX013

What's happened: On 14 September 2026, Janux Therapeutics, a clinical-stage biotechnology company based in San Diego, announced that the first patient has been dosed in a Phase 1 trial of JANX013, an experimental immunotherapy for metastatic castration-resistant prostate cancer — an advanced form of the disease that no longer responds to hormone therapy. JANX013 is designed to strengthen the immune system's attack on tumours by activating a protein called CD28, but only inside the tumour itself, which is intended to limit side effects elsewhere in the body. The trial will test JANX013 in combination with JANX007, Janux's more advanced prostate cancer candidate, with the goal of making anti-tumour immune responses last longer.

Why it matters: Prostate cancer is the most commonly diagnosed cancer in men after skin cancer, and advanced cases still have limited treatment options. Janux's "tumour-activated" technology aims to capture the potency of immune-activating drugs without the toxicities that have held back earlier generations. The start of this combination trial is a step forward for the company's lead clinical franchise.

Read more: BioSpace, 14 September 2026