On Monday, Janux Therapeutics Inc (NASDAQ:JANX) released updated data for its JANX007 in metastatic castration-resistant prostate cancer and JANX008 in late-stage solid tumors.

• As of February 12, 2024, 23 subjects were treated with JANX007 in the dose escalation portion of the Phase 1a trial. An increasing depth of prostate-specific antigen (PSA) declines, RECIST responses at higher doses were observed, and a favorable safety profile was maintained. 
•  At a starting dose ≥ 0.1 mg, 14 of 18 (78%) subjects achieved PSA30 declines, and 10 of 18 (56%) subjects achieved PSA50 declines. 
•  At a starting step dose of ≥ 0.2 mg, 6 of 6 (100%) subjects achieved PSA30 declines, and 5 of 6 (83%) subjects achieved PSA50 declines. 
•  Initial step doses of JANX007 ≥ 0.2 mg drove deeper and more durable PSA responses, including one subject that achieved a PSA90 decline.
•  Cytokine Release Syndrome (CRS) was observed to be temporary and mild, presenting only as low-grade 1 or 2 events, and was quickly managed with treatment. 
•  Janux anticipates providing an update on doses for expansion in the second half of 2024.

• Encouraging signs of clinical activity were observed while a favorable safety profile was maintained. 
•  In one subject with NSCLC treated with JANX008 at 0.15mg once-weekly, a confirmed partial response (PR) by RECIST criteria with 100% reduction of the target lung lesion and elimination of liver metastasis with no CRS or TRAEs has been observed.
•  This subject remains on treatment, and their PR has been maintained through their week-18 scan. 
•  One subject with RCC experienced a 12% reduction in the size of a large RCC mass and significant clinical benefit with Grade 1 CRS.
•  The company continues the dose escalation and optimization portion of the trial for JANX008.