Rajesh Belani

B-cell maturation antigen (BCMA) plays a critical role in regulating B-cell proliferation and survival. There is evidence for BCMA expression in various hematologic malignancies, suggesting that BCMA may play an important role as a biomarker or therapeutic target in these diseases. Given advances in understanding the role of BCMA in B-cell development and the promise of BCMA as a therapeutic target, a systematic review is needed to rigorously assess the evidence for BCMA expression and identify areas of consensus and future research. The objective of this review was to summarize the evidence on BCMA protein and mRNA expression across hematologic malignancies. Using a PubMed database search up to 28 August 2019, a systematic literature review of publications reporting BCMA expression in patients with hematologic malignancies was conducted. Data from published congress abstracts presented at the American Society of Clinical Oncology and the American Society of Hematology were also searched. Studies that assessed BCMA expression (protein or mRNA) in patients of any age with hematologic malignancies were included. A total of 21 studies met inclusion criteria and were included in the review. BCMA was expressed in several hematologic malignancies, including multiple myeloma (MM), chronic lymphocytic leukemia, acute B-lymphoblastic leukemia, non-Hodgkin lymphoma (NHL), and Hodgkin lymphoma. BCMA was expressed at uniformly high levels across all 13 MM studies and at low to moderate levels in acute myeloid leukemia and acute lymphoblastic leukemia. These results suggest that BCMA is a relevant target in MM as well as in a subset of B-cell leukemia. BCMA expression in Hodgkin lymphoma and NHL varied across studies, and further research is needed to determine the utility of BCMA as an antibody target and biomarker in these diseases. Differences in sample type, timing of sample collection, and laboratory technique used may have affected the reporting of BCMA levels.

Multiple myeloma treatment has evolved with approvals of new immunomodulatory imide drugs (IMiDs), monoclonal antibodies (MoABs), and proteasome inhibitors (PIs). We characterized U.S. treatment trends and survival from 2011 to 2019 using Flatiron data from multiple myeloma patients followed from treatment index until death/end of data. Patients (n = 10,553) were primarily (88%) treated in community centers. Frontline PI-IMiD-dexamethasone use increased over time, while IMiD-dexamethasone and PI-dexamethasone use decreased. MoAB-IMiD-dexamethasone use increased in relapsed/refractory disease. In all lines, use of doublets decreased and triplets increased, with triplets becoming the most prescribed combination by 2018–2019, especially in first line (62%). Monotherapy use decreased in first line (19% to 10%) but remained steady in relapsed/refractory disease (∼20%). With each increasing line of therapy, median overall survival decreased (60, 48, 36, 29, 23 months). Survival increased with more recent diagnosis. Our results indicate that the multiple myeloma landscape has evolved significantly in the last decade.

Significance Aminoacyl-tRNA synthetases (aaRSs) catalyze aminoacylation of tRNAs in the first step of protein synthesis in the cytoplasm. However, in higher eukaryotes, they acquired additional functions beyond translation. In the present study, we show that an activated form of tyrosyl-tRNA synthetase (YRS ACT ) functions to enhance megakaryopoiesis and platelet production in vitro and in vivo. These findings were confirmed with human megakaryocytes differentiated from peripheral blood CD34 + hematopoietic stem cells and with human induced pluripotent stem (iPS) cells. The activity of YRS ACT is independent of thrombopoietin (TPO), as evidenced by expansion of the megakaryocytes from iPS cell-derived hematopoietic stem cells from a patient deficient in TPO signaling. These findings demonstrate a previously unrecognized function of an aaRS which may have implications for therapeutic interventions.