Preclinical evaluation of CD8+anti-BCMA mRNA CAR T cells for treatment of multiple myeloma

Chimeric antigen receptor (CAR) T-cell therapy remains limited to select centers that can carefully monitor adverse events. To broaden use of CAR T cells in community clinics and in a frontline setting, we developed a novel CD8+ CAR T-cell product, Descartes-08, with predictable pharmacokinetics for treatment of multiple myeloma. Descartes-08 is engineered by mRNA transfection to express anti-BCMA CAR for a defined length of time. Descartes-08 expresses anti-BCMA CAR for 1 week, limiting risk of uncontrolled proliferation; produce inflammatory cytokines in response to myeloma target cells; and are highly cytolytic against myeloma cells regardless of the presence of myeloma-protecting bone marrow stromal cells, exogenous a proliferation-inducing ligand, or drug resistance including IMiDs. The magnitude of cytolysis correlates with anti-BCMA CAR expression duration, indicating a temporal limit in activity. In the mouse model of aggressive disseminated human myeloma, Descartes-08 induces BCMA CAR-specific myeloma growth inhibition and significantly prolongs host survival (p < 0.0001). These preclinical data, coupled with an ongoing clinical trial of Descartes-08 in relapsed/refractory myeloma (NCT03448978) showing preliminary durable responses and a favorable therapeutic index, have provided the framework for a recently initiated trial of an optimized/humanized version of Descartes-08 (i.e., Descartes-11) in newly diagnosed myeloma patients with residual disease after induction therapy.

Automated summary

The study introduces a novel CD8+ CAR T-cell product, Descartes-08, for the treatment of multiple myeloma, with predictable pharmacokinetics and limited risks of uncontrolled proliferation and drug resistance. Preclinical data and ongoing clinical trials have demonstrated the effectiveness and safety of Descartes-08 in inhibiting myeloma growth and providing durable responses in patients.