Single cell dissection of plasma cell heterogeneity in symptomatic and asymptomatic myeloma

Multiple myeloma (MM), a plasma cell (PC) malignancy, is the second most common blood cancer. Despite extensive research, disease heterogeneity within and between patients is poorly characterized, hampering efforts for early diagnosis and improved treatments. Here, we apply single cell RNA-seq to study the heterogeneity of 40 individuals along the MM progression spectrum. We define malignant PC at single cell resolution, demonstrating high inter-patient variability that can be explained by expression of known MM drivers and additional putative factors. Within newly diagnosed patients, we identify extensive sub-clonal structures for 10/29 patients. In asymptomatic patients with early disease and in minimal residual disease post-treatment, we detect tumor PC for a subset of the patients, with the same drivers of active myeloma. Single cell analysis of rare circulating tumor cells (CTC) allows detection of malignant PC, which reflect the BM disease. Our work establishes scRNA-seq for dissecting blood malignancies and devising detailed molecular characterization of tumor cells in symptomatic and asymptomatic patients. Overall design: The study includes 29 newly diagnosed patients with plasma cell neoplasms and 11 control donors, for which bone marrow plasma cells were single cell sorted by FACS, and their mRNA sequenced. For 11 patients, targeted genomic DNA panel analysis for myeloma was performed.

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Ledergor G, Weiner A, Zada M, Wang SY, Cohen YC, Gatt ME, Snir N, Magen H, Koren-Michowitz M, Herzog-Tzarfati K, Keren-Shaul H, Bornstein C, Rotkopf R, Yofe I, David E, Yellapantula V, Kay S, Salai M, Ben Yehuda D, Nagler A, Shvidel L, Orr-Urtreger A, Halpern KB, Itzkovitz S, Landgren O, San-Miguel J, Paiva B, Keats JJ, Papaemmanuil E, Avivi I, Barbash GI, Tanay A, Amit I