Janux says emerging JANX007 data demonstrates ‘substantial clinical activity’

Janux Therapeutics (JANX) announced positive updated interim clinical data for its JANX007 clinical program. “These clinical data show substantial activity with JANX007 in 5L metastatic castration-resistant prostate cancer patients and provide compelling support for the doses we’ve selected for expansion trials directed at pre-PLUVICTO 2L and 3L patients,” said David Campbell, Ph.D., President and CEO, Janux Therapeutics. “We look forward to rapidly advancing JANX007 into second and third-line therapy where a substantial unmet need remains and where we believe JANX007’s highly differentiated profile could allow for broad usage, if approved. This is an exciting day for Janux, but more importantly the prostate cancer patients we serve.” JANX007 is in a Phase 1a clinical trial in patients with advanced or metastatic prostate cancer (mCRPC). The patients enrolled in the trial were heavily pre-treated with a median of four prior lines of therapy. As of the November 15, 2024 data cutoff, 16 pre-PLUVICTO patients have been treated once-weekly at a target dose ranging from 2 mg to 9 mg in the Phase 1a clinical trial. High prostate-specific antigen (PSA) response rates and deep PSA declines were observed across all doses; 100% of patients achieved best PSA50 declines, 63% of patients achieved best PSA90 declines, and 31% of patients achieved best PSA99 declines. Durability of PSA declines at a target dose greater than or equal to 2 mg were observed; 75% of patients maintained PSA50 declines at greater than or equal to 12 weeks and 50% of patients maintained PSA90 declines at greater than or equal to 12 weeks. Deep and durable PSA responses were observed irrespective of resistance driver aberration status, or prior treatments with a taxane or ARPi. In RECIST-evaluable patients, anti-tumor activity was observed with confirmed and unconfirmed partial responses in 50% (4/8) of patients. JANX007 was well-tolerated with cytokine release syndrome (CRS) and CRS-related adverse events primarily limited to cycle 1 and grades 1 and 2. Similarly, treatment-related adverse events (TRAEs) not associated with CRS were primarily limited to cycle 1 and grades 1 and 2. The maximum tolerable dose for JANX007 has not yet been reached. Based on these efficacy and safety results, two once-weekly step dose regimens have been identified for Phase 1b expansion trials directed at pre-PLUVICTO 2L and 3L patients. Janux anticipates providing another update on JANX007 in 2025.