Cartesian Therapeutics Reports Positive Phase 2b Results for Descartes-08 in Myasthenia Gravis

Cartesian Therapeutics, Inc., a clinical-stage biotechnology firm specializing in mRNA cell therapy for autoimmune diseases, has reported promising results from its Phase 2b trial of Descartes-08 for generalized myasthenia gravis (MG). The trial's primary endpoint was met with statistical significance, showing that 71% of patients treated with Descartes-08 experienced a clinically meaningful improvement in their MG Composite (MGC) score at three months, compared to 25% in the placebo group.

Descartes-08 is a novel mRNA-engineered chimeric antigen receptor T-cell (mRNA CAR-T) therapy targeting the B cell maturation antigen (BCMA). It is designed for outpatient administration, circumventing the need for the lymphodepleting chemotherapy typically required by conventional CAR-T therapies. The U.S. Food and Drug Administration (FDA) has granted Descartes-08 both Regenerative Medicine Advanced Therapy (RMAT) and Orphan Drug Designations for MG.

Dr. Carsten Brunn, President and CEO of Cartesian, emphasized the significance of these findings as a clinical proof-of-concept for their mRNA platform. He noted that the RMAT designation would facilitate ongoing collaboration with the FDA, with plans for an End-of-Phase 2 meeting by year-end.

Myasthenia gravis is a rare autoimmune disorder characterized by severe muscle weakness and fatigue, often necessitating chronic immunosuppressive treatments. Current therapies are linked with broad immunosuppression and limited effectiveness. Dr. Tahseen Mozaffar, a Neurology Professor at the University of California, Irvine, highlighted the deep and durable improvements from Descartes-08, which substantially exceeded what is considered clinically meaningful. He expressed optimism about its potential as a new outpatient treatment option for MG.

The Phase 2b trial involved 36 heavily pre-treated, highly symptomatic MG patients. They were randomized to receive either Descartes-08 or a placebo through six weekly outpatient infusions. At the end of three months, patients on placebo were offered the chance to switch to Descartes-08.

The primary endpoint focused on the proportion of patients achieving a five-point or more reduction in the MGC score—a rigorous measure of MG severity and impact. In the modified intent-to-treat (mITT) population, 71% of Descartes-08 patients achieved this improvement compared to 25% in the placebo group. The safety profile of Descartes-08 was favorable, showing no cases of cytokine release syndrome or immune effector cell-associated neurotoxicity syndrome.

Secondary endpoints confirmed significant improvements across other MG severity scales, such as the Activities of Daily Living (MG-ADL), Quantitative MG (QMG), and MG Quality of Life Revised Scale (MG-QoL-15R). These benefits persisted or even improved at subsequent follow-ups at four and six months.

Additionally, Cartesian shared updated results from two patients in the Phase 2a open-label segment of the trial. Both patients experienced rapid and sustained improvements after a second treatment cycle, maintaining minimal symptoms for up to a year.

Cartesian's announcement also included the initiation of a clinical trial to evaluate Descartes-08 in systemic lupus erythematosus (SLE). This Phase 2 open-label trial aims to include up to 30 adult patients with moderate to severe, treatment-resistant SLE.

In another development, Cartesian appointed Dr. Kemal Malik to its Board of Directors. Dr. Malik brings over 30 years of global pharmaceutical expertise, enhancing Cartesian's strategic and regulatory capabilities.

Descartes-08 represents a promising advancement in mRNA cell therapy for autoimmune diseases, distinguishing itself with its outpatient applicability and avoidance of preconditioning chemotherapy. Cartesian continues to pioneer mRNA-based therapeutic solutions, aiming to address significant unmet needs in autoimmune disease treatment.