Janux Therapeutics, a clinical-stage biopharmaceutical company, recently announced positive updated interim clinical data from its Phase 1a dose escalation trial for JANX007, a novel PSMA-TRACTr (Prostate-Specific Membrane Antigen – Tumor Activated T Cell Engager) therapy for metastatic castration-resistant prostate cancer (mCRPC). The data, presented at a virtual investor event on December 2, 2024, showed that JANX007 was well-tolerated and demonstrated substantial clinical activity in patients with mCRPC who had received a median of four prior lines of therapy.

The key findings from the trial include:

• High PSA response rates: All 16 patients treated in the trial achieved at least a 50% decline in their PSA levels (PSA50).
• Deep PSA declines: 63% of patients achieved at least a 90% decline in PSA levels (PSA90), and 31% achieved at least a 99% decline (PSA99)
• Durable PSA response: 75% of patients maintained PSA50 declines for at least 12 weeks, and 50% maintained PSA90 declines for at least 12 weeks.
• Encouraging anti-tumor activity: In the eight patients who were evaluable for tumor response by RECIST criteria, 50% achieved an objective response rate (ORR), including confirmed and unconfirmed partial responses.
• Well-tolerated safety profile: The most common side effects were cytokine release syndrome (CRS) and treatment-related adverse events (TRAEs), which were mostly limited to the first cycle of treatment and were generally mild (Grade 1 or 2).

The maximum tolerable dose for JANX007 has not yet been reached.

Based on these encouraging efficacy and safety results, Janux has selected two once-weekly step dose regimens for Phase 1b expansion trials in patients with mCRPC who have not yet received PLUVICTO. The company plans to provide another update on the JANX007 program in 2025.

Janux Therapeutics is dedicated to developing tumor-activated immunotherapies for cancer. Their proprietary TRACTr and TRACIr platforms aim to provide cancer patients with safe and effective treatments by harnessing their own immune system to target and destroy tumor cells while minimizing safety concerns.

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