Publication Date:
2020-11-05
Description:
Introduction: B-cell maturation antigen (BCMA) is primarily expressed by malignant and normal plasma cells, making it an attractive target for the treatment of multiple myeloma (MM). bb21217 is a BCMA-directed chimeric antigen receptor (CAR) T cell therapy that uses the same CAR molecule as idecabtagene vicleucel (ide-cel, bb2121), but adds the PI3K inhibitor bb007 during manufacturing to enrich the drug product (DP) for memory-like T cells, thereby reducing the proportion of highly differentiated or senescent T cells. We conducted correlative analyses to investigate the mechanistic hypothesis that CAR+ T cells with memory like phenotypes may persist and function longer, which may be one determinant of duration of response (DOR). Methods: An ongoing phase I clinical study (CRB-402; NCT03274219) is assessing safety and efficacy of bb21217 in relapsed/refractory MM patients. A total of 44 patients had PBMCs, collected from apheresis, and DP characterized by RNA sequencing (RNAseq) and mass Cytometry (CyTOF). The correlation of T cell phenotype with peak expansion, response and DOR per IMWG Uniform Response Criteria was explored. P-values were determined by Wilcoxon test, Spearman correlation, or Cox PH regression on DOR with categorical marker values (high/low). Results: In this patient population, substantial cross patient heterogeneity in T cell phenotypes was observed both in PBMCs and DP. Late differentiation/senescent markers in PBMCs were negatively correlated with clinical response. In particular, patients whose DP had higher expression of CD57 had lower peak expansion (p
Print ISSN:
0006-4971
Electronic ISSN:
1528-0020
Topics:
Biology
,
Medicine
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