1:Programa Hemato-Oncologia. Cima Universidad de Navarra. IdiSNA.; 2:Programa de Biologia Computacional. Cima Universidad de Navarra. IdiSNA.; 3:Departamento de Hematología y Terapia Celular. Clínica Universidad de Navarra. IdiSNA.; 4:Servicio de Hematologia, Hospital Universitario de Navarra. IdiSNA.; 5:Departamento de inmunologia e inmunoterapia, Clinica Universidad de Navarra.; 6:Programa inmunologia e inmunoterapia. Cima Universidad de Navarra. IdiSNA.; 7:Centro de Investigación Biomédica en Red de Cancer (CIBERONC).

Refractory or relapsed (R/R) multiple myeloma (MM) is nowadays an incurable disease. CAR-T immunotherapy against BCMA has proven its efficacy with complete response rates of 83-85%. However, despite the initial favorable response, all patients relapse with a progression free survival time of 8-12 months. We hypothesize that this lack of long-term response could be related to fitness and functionality of the CAR-T cells generated from these patients with R/R MM. Thus, we believe that CAR-T cells generated from patients in the early stages of the disease would be more functional.

The objective of this work is to perform a phenotypic and functional characterization of CAR-T produced from healthy donors and MM patients at different disease stage (MGUS, SMM, MM and R/R MM). Thus, we have generated BCMA-targeting CAR-T from each group of donor/patients that were fully characterized using flow cytometry and functional assays including cytotoxicity, cytokine production and in vivo antitumoral efficacy. We observed that CAR-T cells produced from MM and R/R MM patients showed decreased memory phenotype, a reduced cytotoxicity against MM cell lines and lower production of IFNg, suggesting that long-term functionality of CAR-T cells from those patients would be compromised. Transcriptomic analyses by RNAseq corroborated functional results providing valuable mechanistic insights.

In conclusion, our results indicate that CAR-T generated from patients with later stages of the disease show phenotypes associated with worst prognosis and less functionality than those produced from healthy donors or patients in early stages of the disease.