Cabaletta Bio Reports Promising CAR-T Therapy Results Across Multiple Autoimmune Diseases, Plans for Pivotal Trials

PHILADELPHIA, PA – June 12, 2025 – Cabaletta Bio (Nasdaq: CABA) today announced updated clinical results for its CAR-T therapy in three distinct autoimmune diseases – myositis, systemic lupus erythematosus (SLE), and systemic sclerosis (SSc) – with plans to initiate pivotal trials for potential FDA approval. The new data, presented at the annual European Alliance of Associations for Rheumatology (EULAR) conference in Barcelona, demonstrate significant clinical improvements and, in some cases, remission, reinforcing the potential of CAR-T technology beyond oncology.

Cabaletta’s CAR-T therapy is designed to target and deplete B cells, which are believed to play a critical role in the pathogenesis of these autoimmune conditions. As of May 30, 2025, 24 patients have been dosed across its Phase 1/2 trials.

Key Clinical Highlights (Data Cutoff: May 6, 2025):

• Myositis: Seven of eight patients achieved a clinical response while off all immunomodulators, with some still tapering off steroids. These responses have been sustained through the data cutoff. Myositis refers to a group of severe, disabling, and potentially life-threatening autoimmune diseases characterized by muscle inflammation and weakness.
• Systemic Lupus Erythematosus (SLE): All seven lupus patients with sufficient follow-up time experienced substantial reductions in disease activity, also while off immunomodulators and glucocorticoids. Notably, three of four patients without kidney disease achieved remission, and one patient with kidney disease achieved remission along with a return of kidney function measures to near-normal. Lupus is a chronic autoimmune disease that can affect various organs and tissues.
• Systemic Sclerosis (SSc): One of two patients with systemic sclerosis responded to the experimental treatment based on a composite disease measure, and both showed “meaningful” improvements in skin thickening and hardening, a hallmark feature of the disease.

Safety Profile:

Cabaletta reported no new serious safety concerns for the CAR-T therapy. While several patients experienced mild cytokine release syndrome (CRS), characterized by transient fever, the company did acknowledge two previously reported cases of immune effector cell-associated neurotoxicity syndrome (ICANS). ICANS is a neurotoxicity that can occur with CAR-T therapies, and its emergence in autoimmune patients has been closely monitored by analysts and industry insiders, raising questions about risk-benefit profiles for these therapies in autoimmune conditions.

Path to Regulatory Approval:

Buoyed by these positive results, Cabaletta is accelerating its regulatory strategy. The biotech plans to:

• Initiate enrollment for two registrational cohorts for myositis later this year.
• Engage with the FDA to discuss registrational studies for lupus in the third quarter of this year.
• Engage with the FDA to discuss registrational studies for systemic sclerosis in the fourth quarter of this year.
• Discuss studies in myasthenia gravis with the FDA next year.