Descartes-08 CAR-T Cells in Generalized Myasthenia Gravis (MG)

In Part 3, the primary objective is to compare the effect of Descartes-08 versus placebo, as measured by the change in MGC score from baseline to Week 12. In Part 1, up to three ascending doses of Descartes-08 will be administered to each of 3 to 6 patients; the patients will be staggered at least 21 days apart and will complete a safety review between each dose. In Part 2, patients will receive up to 6 doses in three different schedules depending on the arm they were enrolled into and will be monitored for up to 1 year to assess the safety and tolerability of a repeated dosing schedule.

The proportion of patients achieving a ≥6-point change from Baseline at each posttreatment follow-up in the MG ADL score and QMG score (all parts), and the difference between this proportion in the treatment arm compared to placebo at Day 85.

The proportion of patients initially randomized to placebo who then cross over to Descartes-08 and achieve a ≥5-point reduction in MGC score from Crossover Day

1 to Crossover Day 85.

Determine the change from baseline over a period of 24 weeks in the titer of myasthenia specific autoantibody titers, e.g. nicotinic acetylcholine receptor autoantibody (anti-nAChR) or muscle-specific tyrosine kinase autoantibody (anti- MusK or anti-Low-Density-Lipoprotein-Related-Protein4 (anti-LRP4) or anti-AChR cluster antibody and the 4 Immunoglobulin types (IgG, IgM, IgA, IgE) following single or multiple infusions of Descartes-08 in MG auto-antibody seropositive patients (Parts 1 and 2 only)

Quantify the clinical effect of single or multiple infusions of Descartes-08 on patients by standard clinical assessment scales (MG ADL, QMG, MG QoL 15R, MG PIS, MG Composite) over a period of 24 weeks in MG auto-antibody seropositive and seronegative patients together and separately (all parts).