Tr1X Receives FDA Clearance for CAR-Treg Therapy in Progressive MS

SAN DIEGO, CA — October 15, 2025 — Tr1X, a clinical-stage biopharmaceutical company focused on allogeneic cell therapies for autoimmune and inflammatory diseases, announced the U.S. Food and Drug Administration (FDA) has cleared its Investigational New Drug (IND) application for TRX319 in progressive multiple sclerosis (MS).

This regulatory milestone is paired with a significant financial boost: the company also announced a $50 million venture financing round, which is expected to extend its cash runway into 2027. This funding is crucial for advancing the newly cleared TRX319 study and continuing the ongoing Phase 1/2a trial for its lead program, TRX103, for refractory Crohn’s disease.

Advancing into the Clinic with a Targeted Approach

TRX319 is an allogeneic, CAR-Tr1 Treg cell therapy—a next-generation therapeutic designed to pair targeted B-cell control with active anti-inflammatory signaling and pathogenic T-cell modulation. The therapy leverages an AAV-like mechanism within its cell product design to ensure CNS-penetrant delivery.

The company is on track to initiate the TRX319 Phase 1/2a dose-escalation trial in early 2026. This multicenter, open-label study will prioritize safety and tolerability while assessing pharmacodynamic, clinical disability, and biomarker objectives in patients with progressive MS, a condition currently limited in therapeutic options.

“We are pleased to receive IND clearance for TRX319 and to advance our second program into the clinic in early 2026,” said David de Vries, co-founder and CEO of Tr1X. He added that the new financing “further underscores investor confidence in our differentiated allogeneic Tr1 and CAR-Tr1 Treg strategy.”

Expert Support and Preclinical Rationale

Experts emphasized the importance of this new therapeutic approach for progressive MS, a condition notorious for disability accumulation outside of defined relapses.

Jennifer Graves, M.D., Ph.D., of the University of California San Diego, stated that the “exploration of new approaches, such as this first-in-human study of an allogeneic CAR-Tr1 Treg cell therapy… is timely and important.”

Preclinical data supported the IND clearance, showing that TRX319 demonstrated robust Central Nervous System (CNS) penetration and CD19-specific cytotoxicity. The therapy also exhibited key regulatory features, including IL-10–associated activity on self-reactive T cells and activated microglia, and the suppression of pro-inflammatory cytokines.

Bruce Cree, M.D., Ph.D., of the University of California San Francisco, noted that an approach that “targets B-cell biology while actively modulating inflammatory signaling within a regulatory cell-therapy framework is a distinct and promising hypothesis in progressive MS.”

Progress with Lead Candidate TRX103

The company is also encouraged by early safety, PK/PD, and clinical signals from its ongoing studies of its lead product, TRX103, for refractory Crohn’s disease and mismatched hematopoietic stem cell transplant. TRX103 is an off-the-shelf engineered T cell product designed to mimic the function of type 1 regulatory (Tr1) cells to dampen inflammation and restore immune tolerance, with a profile designed to avoid lymphodepletion commonly associated with other cell therapies. Tr1X plans to share initial data from these trials in the coming months.