Cartesian licenses mRNA payload to WestGene for in vivo CAR-T
Cartesian Therapeutics has signed a strategic licensing agreement with Chinese biotech WestGene Biopharma to develop in vivo CAR-T therapies for autoimmune diseases, combining Cartesian's clinically tested mRNA payloads with WestGene's targeted lipid nanoparticle (tLNP) delivery platform.
The NASDAQ-listed company (RNAC) said the collaboration will initially focus on a Phase 1 dose-escalation study in patients with generalised myasthenia gravis (MG), using the mRNA construct from its lead asset Descartes-08 delivered via WestGene's proprietary tLNPs. The trial is expected to initiate in the second half of 2026, with in-human data anticipated in the first half of 2027.
The deal
Under the terms of the agreement, WestGene receives an upfront payment and is eligible for development and commercial milestone payments; the financial quantum was not disclosed. The partnership was brokered by Chapel Hill-based intermediary Uni-Pioneers BioMed.
The trial will use a Bayesian Optimal Interval (BOIN) adaptive design across multiple dose levels, with a translational assessment package covering clinical response measures. The in vivo approach, if it yields positive proof-of-concept data, is intended to eliminate the ex vivo manufacturing step that characterises conventional autologous CAR-T production — a significant operational and cost burden that has historically limited the scalability of cell therapies.
Carsten Brunn, President and CEO of Cartesian, said the collaboration provides "an accelerated and efficient path to human clinical data" and that the company intends, contingent on positive MG results, to advance programmes across multiple autoimmune indications into US clinical development. Beyond Descartes-08, Cartesian is also planning to evaluate internally developed next-generation anti-BCMA CAR constructs and a BCMA-directed T-cell engager (TCE) through the WestGene platform.
WestGene's tLNP technology has been evaluated in earlier clinical studies across oncology and autoimmune settings using mRNA CAR-T constructs. The company reported no dose-limiting toxicities, serious adverse events, or ICANS across multiple dosing regimens — including up to 14 doses in a single patient — with only one Grade 1 cytokine release syndrome event recorded. High levels of circulating CD8⁺ CAR-T cells and sustained B-cell depletion were observed, and CAR expression was maintained on repeat dosing.
Market context
The in vivo CAR-T field is attracting growing attention as a potential route around the logistical and manufacturing constraints of ex vivo cell therapies. Several academic groups and early-stage companies are pursuing LNP-based and viral-vector-based in vivo T-cell engineering approaches, and the autoimmune indication is increasingly viewed as a near-term proving ground ahead of oncology applications, where tumour heterogeneity poses additional engineering challenges.
Cartesian itself is a relatively rare example of a company with late-stage clinical data in autoimmune CAR-T: Descartes-08 is in Phase 3 development for MG, Phase 2 for myositis, and Phase 1/2 for paediatric autoimmune diseases. That existing clinical infrastructure gives the company a credible basis for a rapid read-through from the new in vivo programme. Investors will focus on whether the WestGene tLNP platform can replicate the efficacy signals seen with autologous Descartes-08 while delivering the simpler administration profile that in vivo approaches promise. The 1H 2027 data readout will be an early test of that thesis.