在MM细胞存在GPRC5D的情况下，Talquetamab改变T细胞转录组

Background : G protein-coupled receptor class C group 5 member D (GPRC5D) has emerged as a promising immune target in multiple myeloma (MM). Talquetamab, a GPRC5D-directed bispecific antibody, has shown an efficacy of 70% in triple class refractory MM patients however, genomic loss mediated relapse is often observed. To better understand the interplay of talquetamab, GPRC5D loss and T cells within the immune microenvironment, we performed single cell sequencing on a coculture of GPRC5D loss models and healthy T cells in presence and absence of talquetamab. Methods : GPRC5D mono- and biallelic knockout models were generated using CRISPR-Cas9 technology. Cocultures were established using healthy T cells with or without talquetamab for 24 hours. CITE-seq was performed. Cell hashing with TotalSeq-C antibodies enabled multiplexing. Pooled cells underwent 10x Genomics 5' GEM-X workflow and were sequenced on Illumina NovaSeq X Plus. Differential gene expression was assessed using the Wilcoxon rank-sum test, and interferon response scores were calculated using AddModuleScore. Results: Pronounced transcriptomic changes in MM cells were observed with both mono- and bi-alleic loss of GPRC5D via CITE-seq. Based on the expression of canonical markers ( IL2RA, IRF4, TNFRSF4-18, TNF, IFNG ), CD4 and CD8 activated T cells were only observed in presence of talquetamab and GPRC5D + cells and completely disappeared when stimulated with GPRC5D D el/ D el models. A significant induction of interferon stimulated genes ( GBP2-4-5, IFI44, IFIT2, ISG15 ) in presence of talquetamab with GPRC5D on MM cells (p-value < 0.001, absolute log2FC > 2) was observed across T cell subpopulations. Interferon signaling genes ( STAT1, IRF1 ) were found to be upregulated in T cells by talquetamab alone even in absence of GPRC5D + cells in coculture. Additionally, we also identified genes only upregulated in presence of GPRC5D and talquetamab, including SOCS3, CD69, JUNB, BATF, CISH , and PRDM1 , indicating a unique activation status of these T cells. Gene set enrichment analysis performed on T cell sub types indicated an enrichment of IFN-gamma and IFNA-signaling (NES>2.0, FDR 0,0) in CD4, CD8, Tcm and Treg populations. Additionally, IL2-STAT5 signaling and inflammatory response (NES>2.0, FDR 0.0) pathways were found to be enriched only in presence of talquetamab and GPRC5D + cells. Of note, in the absence of talquetamab, T cells transcriptomic profile did not change in response to GPRC5D presence or absence on MM cells. Conclusions: Our findings demonstrate that talquetamab upregulates the expression of interferon signaling genes in T cells even in the absence of GPRC5D and this response is enhanced when GPRC5D is present on MM cells. Moreover, talquetmab alters the activation profile across T cells subsets and both abundance and distribution of different T cells subpopulations is changed by GPRC5D status of the MM cells in coculture.