Janux Therapeutics Announces Positive Interim Clinical Data from Phase 1a Dose Escalation for PSMA-TRACTr JANX007 and an Update on Pipeline Programs

On July 17, 2023 Janux Therapeutics, Inc. (Nasdaq: JANX) (Janux), a clinical-stage biopharmaceutical company developing a broad pipeline of novel immunotherapies by applying its proprietary technology to its Tumor Activated T Cell Engager (TRACTr) and Tumor Activated Immunomodulator (TRACIr) platforms, reported interim Phase 1 clinical data for PSMA-TRACTr JANX007 in adult subjects with metastatic castration-resistant prostate cancer (mCRPC) and provided a pipeline update (Press release, Janux Therapeutics, JUL 17, 2023, View Source [SID1234633263]). Janux will host a virtual investor event today at 4:00 PM ET. To register for the event, please click here.

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"These data showing tumor-activated T cell engagement in patients with prostate cancer represent the first in-human data for the TRACTr platform and give us confidence for continuing clinical development of JANX007 and advancing future programs from this platform. We are encouraged by these positive interim clinical data for JANX007, which displayed PSA reductions coupled with low-grade and transient CRS, which we believe to be consistent with the TRACTr mechanism of action" said David Campbell, Ph.D. "The concept of tumor-specific activation as a new therapeutic strategy for T cell engagers in solid tumors has taken an important step forward, and the JANX007 program has hit an important milestone in its clinical development."

Interim Clinical Data for PSMA-TRACTr JANX007 in mCRPC as of June 28, 2023

The data from eight patients from the first three cohorts of the dose escalation portion of the Phase 1a clinical trial, as of June 28, 2023 show that JANX007 has been generally well tolerated, with no dose-limiting toxicities. JANX007 has been dosed at 300µg flat dose, which is above the projected maximum tolerable dose of the parental T cell engagers. JANX007 showed clinical activity at both 100µg and 300µg flat doses and yielded best overall PSA reductions between 31% and 67% in four of the five patients who received a flat dose. Grade 1 or 2 cytokine release syndrome (CRS) was observed only in patients who demonstrated PSA reductions, suggesting cytokine release resulting from anti-tumor activity was associated with CRS. No Grade 3 CRS has been observed. The most common, non-CRS related adverse event observations have been generally consistent with tumor-specific activity and reduced PSMA(+) healthy tissue activity. No transaminitis was observed. JANX007 clinical development has moved into step-dosing and dose optimization with the goal to enhance efficacy while maintaining suitable safety results.

The TRACTr technology is designed to create potent T cell engagers (TCEs) by tumor-specific activation via mask cleavage by tumor proteases. Plasma levels in patients exhibited prolonged TRACTr exposure, clear evidence of activation as measured by a specific cleavage fragment, and lack of accumulation of the active TCE in the blood. The lack of TCE accumulation shows consistency with TRACTr design principles and suggest that observed PSA reductions have been a result of tumor activation and not systemic TCE exposure.