PHILADELPHIA, PA — Cabaletta Bio (Nasdaq: CABA) reported new clinical data suggesting its lead CAR-T cell therapy candidate could support regulatory filings in multiple autoimmune diseases, prompting the company to expand development plans beyond myositis to include systemic sclerosis and pediatric indications.
The data, presented at the European Alliance of Associations for Rheumatology Congress in London, showed durable responses across studies of rese-cel, an investigational CD19-directed CAR-T therapy designed to reset the immune system after a single treatment.
The results are particularly significant for Cabaletta because they support potential registrational pathways in diseases with limited treatment options while broadening the commercial opportunity for the therapy across multiple autoimmune conditions.
In dermatomyositis and antisynthetase syndrome, eight of 10 patients in the Phase 1/2 RESET-Myositis study would have met the primary endpoint planned for the registrational cohort, according to the company.
Among dermatomyositis patients, 83% achieved a moderate-to-major improvement score after discontinuing immunomodulatory therapies, and all maintained those responses through follow-up periods extending as long as 18 months.
The first juvenile dermatomyositis patient treated with rese-cel also achieved a moderate response while remaining off immunomodulators, with benefits maintained through 32 weeks of follow-up.
Cabaletta indicated juvenile dermatomyositis is expected to be included in a biologics license application planned for the second half of 2027. The company noted that inclusion of the pediatric indication could make the program eligible for a priority review voucher.
The company also elevated systemic sclerosis to a pivotal development program following data showing continued improvement in skin and lung disease among treated patients.
Based on discussions with the U.S. Food and Drug Administration and Phase 1/2 findings, Cabaletta plans to initiate a registrational study in approximately 25 patients with systemic sclerosis-associated interstitial lung disease during the fourth quarter of 2026.
Patients with lung involvement demonstrated a median 7.5% improvement in predicted forced vital capacity after 36 weeks, while most evaluable patients achieved meaningful improvements on systemic sclerosis response measures.
In lupus, Cabaletta reported early evidence that a preconditioning-free version of the therapy may still achieve the deep B-cell depletion believed to be necessary for an immune reset.
One of the first two lupus patients treated without preconditioning achieved deep B-cell depletion comparable to patients previously treated with standard preconditioning regimens. The second patient experienced approximately 90% reduction in peripheral B cells.
The findings could be commercially important because eliminating preconditioning chemotherapy may simplify treatment and potentially broaden patient eligibility if efficacy is maintained.
Across studies, the company reported generally manageable safety findings. Most patients experienced either no cytokine release syndrome or only Grade 1 events, while immune effector cell-associated neurotoxicity syndrome was uncommon.
Chief Medical Officer David Chang said the data suggest the pivotal myositis study may have a favorable probability of success based on observed response rates.
“Over 80% of the Phase 1/2 dermatomyositis patients would have achieved the pivotal primary endpoint and all five of these patients maintained their response through the latest follow-up as long as 1.5 years,” Chang said.
The company expects to report topline data from its registrational dermatomyositis and antisynthetase syndrome cohort in mid-2027 and plans to continue enrolling patients across multiple autoimmune disease programs.
For investors, the update marks an expansion of Cabaletta’s strategy from testing proof-of-concept in individual autoimmune diseases to pursuing a broader platform approach in which a single CAR-T therapy could potentially address multiple immune-mediated disorders through a one-time treatment.
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