Janux Therapeutics Doses First Patient in Phase 1 Trial of JANX011 for Autoimmune Diseases

Janux Therapeutics has dosed the first participant in a Phase 1 clinical study of JANX011, a CD19-targeted bispecific engineered using the company's proprietary Adaptive Immune Response Modulator (ARM) platform. JANX011 is being developed for autoimmune diseases and is designed to enable deep and durable immune reset through targeted depletion of CD19-expressing B cells in blood and tissue.

JANX011 is the first clinical candidate from Janux's proprietary ARM platform, which is designed to deliver sustained target B-cell depletion by harnessing an adaptive-like immune response while improving the safety and convenience of immune-engaging therapies. Unlike conventional T-cell engagers, which typically require repeated dosing to maintain B-cell depletion, ARM molecules are engineered to drive controlled T-cell expansion while target cells are present, followed by contraction after target cell elimination. This response is designed to enable deep tissue-level target cell clearance without the need for lymphodepletion or pre-conditioning.

In preclinical studies, a single, subcutaneous dose of JANX011 demonstrated deep and durable B-cell depletion in both blood and tissue compartments along with prolonged memory B-cell reset. Across a greater than 100-fold preclinical dose range, cytokine levels remained low, supporting a wide safety window and reduced risk of cytokine release syndrome while maintaining ongoing target cell depletion.

The Phase 1 study (NCT07291323) is an open-label, dose-escalation trial designed to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of JANX011 in healthy adult volunteers. The study is intended to characterize key immune effects, including B-cell depletion, memory B-cell reset, T-cell expansion, and cytokine release risk. The study is expected to generate early pharmacodynamic insights to inform dose selection and prioritization of autoimmune indications for subsequent clinical development.

The president and CEO stated that dosing the first participant with JANX011 marks an important milestone for Janux and the first clinical evaluation of the ARM platform. While JANX011 is initially being developed for autoimmune diseases, the differentiated immune profile of the ARM platform may also have broader implications across CD19-expressing diseases, including hematologic malignancies.

The chief scientific officer and co-founder stated that based on compelling preclinical data, JANX011 has the potential to achieve pharmacodynamic effects comparable to those seen with CAR-T therapies, including stable immune cell population changes and reductions in autoantibody drivers of disease, while offering the safety, convenience, and re-dosing flexibility required for autoimmune patients.

In May 2025, Janux started Phase Ib expansion trials with JANX007 in the first-in-human ENGAGER-PSMA-01 clinical trial, aimed at treating advanced metastatic castration-resistant prostate cancer. Janux is 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), Tumor Activated Immunomodulator (TRACIr), and ARM platforms.