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Immunoglobulin light chain (AL) amyloidosis is an incurable hematologic disorder typically characterized by the production of amyloidogenic light chains by clonal plasma cells. These light chains misfold and aggregate in healthy tissues as amyloid fibrils, leading to life-threatening multi-organ dysfunction. Here we show that the clonal plasma cells in AL amyloidosis are highly primed to undergo apoptosis and dependent on pro-survival proteins MCL-1 and BCL-2. Notably, this MCL-1 dependency is indirectly targeted by the proteasome inhibitor bortezomib, currently the standard of care for this disease and the related plasma cell disorder multiple myeloma, due to upregulation of pro-apoptotic Noxa and its inhibitory binding to MCL-1. BCL-2 inhibitors sensitize clonal plasma cells to multiple front-line therapies including bortezomib, dexamethasone and lenalidomide. Strikingly, in mice bearing AL amyloidosis cell line xenografts, single agent treatment with the BCL-2 inhibitor ABT-199 (venetoclax) produces deeper remissions than bortezomib and triples median survival. Mass spectrometry-based proteomic analysis reveals rewiring of signaling pathways regulating apoptosis, proliferation and mitochondrial metabolism between isogenic AL amyloidosis and multiple myeloma cells that divergently alter their sensitivity to therapies. These findings provide a roadmap for the use of BH3 mimetics to exploit endogenous and induced apoptotic vulnerabilities in AL amyloidosis., (© 2022. The Author(s).)

Adverse events affecting Black patients, including skin hyperpigmentation, may be overlooked using existing clinical trial data on lenalidomide. The objective of this systematic review is to characterize the representation of Black participants and rate of skin hyperpigmentation in clinical trials. In this systematic review and pooled analysis of 21 clinical trials comprising 4539 participants, the proportion of Black participants in trials (6.9%, n = 315) was significantly less than the multiple myeloma population (p < 0.001). The rate of skin hyperpigmentation (0.066%, n = 3) and all skin changes (6.4%, n = 291) was significantly less compared to a 40.8% incidence in a recent retrospective study (p. <0.001). Among participants undergoing treatment with lenalidomide for multiple myeloma, Black patients were underrepresented and the adverse event of skin hyperpigmentation was underreported. Fair representation of Black patients in clinical trials is needed to better describe this adverse event and other events that may be underreported., (Copyright © 2022 Elsevier B.V. All rights reserved.)