Cabaletta Bio Inc. saw its stock price jump approximately 32% in late trading Monday, driven by early-stage clinical results from its cell therapy program and the announcement of a $150 million equity offering that included participation from pharmaceutical giant Eli Lilly. Shares reached $3.895 on heavy volume, with an intraday high of $4.04.
The Philadelphia-based biotechnology company priced 51.7 million shares at $2.90 each, an at-the-market transaction compliant with Nasdaq rules. The offering attracted a range of institutional investors, including Bain Capital Life Sciences, Adage Capital Management, Cormorant Asset Management, as well as mutual and sovereign wealth funds, alongside Eli Lilly.
Proceeds from the stock sale bolster Cabaletta's balance sheet. According to a preliminary prospectus supplement, the company held approximately $117 million in cash and equivalents as of March 31. Combined with the new funds, management expects sufficient resources to cover operating and capital expenditures through mid-2027.
The clinical data that sparked investor enthusiasm came from a small trial of rese-cel (formerly CABA-201), an investigational CD19-directed CAR-T therapy. In four patients with refractory pemphigus vulgaris—a severe autoimmune blistering disease—the therapy was administered at the lowest dose without preconditioning chemotherapy, which typically involves cyclophosphamide and fludarabine.
Results from the April 2 data cutoff showed that two of the four patients demonstrated what the company termed 'compelling clinical activity' at six months. Three patients remained off immunomodulators and steroids, and the same number achieved complete peripheral B-cell depletion, a key pharmacodynamic marker. Safety data revealed one case of Grade 1 cytokine release syndrome, but no instances of immune effector cell-associated neurotoxicity syndrome, a known CAR-T risk.
Cabaletta has begun enrolling additional patients into a higher-dose cohort of the RESET-PV study, with durability data expected in the second half of 2026. The company plans to present full results at the American Society of Gene & Cell Therapy meeting on May 14 in Boston.
Beyond pemphigus vulgaris, Cabaletta's RESET program is evaluating rese-cel in multiple autoimmune indications, including lupus, myositis, systemic sclerosis, and generalized myasthenia gravis. The company is particularly focused on myositis, having initiated a registrational cohort for dermatomyositis and anti-synthetase syndrome in December 2025. The 17-patient study could support a biologics license application as early as 2027.
Manufacturing scalability remains a critical factor. Cabaletta recently signed a supply agreement with Cellares, aiming to leverage automated production via the Cell Shuttle platform. CEO Steven Nichtberger highlighted the potential to treat 'thousands of patients per year with minimal capital investment,' while Cellares CEO Fabian Gerlinghaus noted that autoimmune applications will require a significantly larger manufacturing footprint than oncology CAR-T.
The competitive landscape is intensifying. Kyverna Therapeutics is advancing its CAR-T candidate KYV-101 in lupus nephritis, multiple sclerosis, myasthenia gravis, and systemic sclerosis. Cartesian Therapeutics is developing Descartes-08 for generalized myasthenia gravis and myositis, also without preconditioning chemotherapy.
Despite the positive market reaction, significant risks remain. Monday's data are based on only four patients at the lowest dose. Questions around durability, higher-dose safety, manufacturing consistency, and regulatory approval persist. Additionally, the prospectus notes that management has broad discretion over the use of proceeds, with no guarantee of optimal deployment.
