XPO1 Enables Adaptive Regulation of mRNA Export Required for Genotoxic Stress Tolerance in Cancer Cells

Novel Targets and Advanced Therapies in Diffuse Large B Cell Lymphomas

Since the introduction of rituximab in the late 1990s, significant progress has been made in advancing targeted therapies for B cell lymphomas, improving patients' chance of being cured and clinicians' therapeutic armamentarium. A better understanding of disease biology and pathogenic pathways, coupled with refinements in immunophenotypic and molecular diagnostics, have been instrumental in these achievements. While traditional chemotherapy remains fundamental in most cases, concerns surrounding chemorefractoriness and cumulative toxicities, particularly the depletion of the hemopoietic reserve, underscore the imperative for personalized treatment approaches. Integrating targeted agents, notably monoclonal antibodies, alongside chemotherapy has yielded heightened response rates and prolonged survival. A notable paradigm shift is underway with innovative-targeted therapies replacing cytotoxic drugs, challenging conventional salvage strategies like stem cell transplantation. This review examines the landscape of emerging targets for lymphoma cells and explores innovative therapies for diffuse large B cell lymphoma (DLBCL). From Chimeric Antigen Receptor-T cells to more potent monoclonal antibodies, antibody-drug conjugates, bispecific antibodies, checkpoint inhibitors, and small molecules targeting intracellular pathways, each modality offers promising avenues for therapeutic advancement. This review aims to furnish insights into their potential implications for the future of DLBCL treatment strategies.

Nuclear to cytoplasmic transport is a druggable dependency in MYC-driven hepatocellular carcinoma

The MYC oncogene is often dysregulated in human cancer, including hepatocellular carcinoma (HCC). MYC is considered undruggable to date. Here, we comprehensively identify genes essential for survival of MYChigh but not MYClow cells by a CRISPR/Cas9 genome-wide screen in a MYC-conditional HCC model. Our screen uncovers novel MYC synthetic lethal (MYC-SL) interactions and identifies most MYC-SL genes described previously. In particular, the screen reveals nucleocytoplasmic transport to be a MYC-SL interaction. We show that the majority of MYC-SL nucleocytoplasmic transport genes are upregulated in MYChigh murine HCC and are associated with poor survival in HCC patients. Inhibiting Exportin-1 (XPO1) in vivo induces marked tumor regression in an autochthonous MYC-transgenic HCC model and inhibits tumor growth in HCC patient-derived xenografts. XPO1 expression is associated with poor prognosis only in HCC patients with high MYC activity. We infer that MYC may generally regulate and require altered expression of nucleocytoplasmic transport genes for tumorigenesis.

XPO1-Mediated mRNA Export of Genome Maintenance Regulators Drives Chemotherapy Resistance in Aggressive Lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoid malignancy and displays vast genetic and transcriptomic heterogeneity. Current treatment guidelines recommend first-line chemoimmunotherapy consisting of an anthracycline backbone, which produces cure rates of approximately 65%. However, the remaining patients will face relapsed or refractory disease, which, even in the era of chimeric antigen receptor T cells, is difficult to treat. In this issue of Cancer Research, Marullo and colleagues investigate the biological underpinnings of the tumor-suppressive activity of the newly approved XPO1 inhibitor selinexor in the treatment of lymphoma. In a translational effort covering genomic and biochemical approaches, combined with in vivo validation experiments and a phase I clinical trial, they demonstrate that upon DNA damage, XPO1 selectively exports transcripts encoding proteins involved in genome maintenance via the RNA-binding proteins THOC4 and eIF4E. Pharmacologic interception of this export process enhances chemosensitivity in various lymphoma models, and combined selinexor plus chemoimmunotherapy displays a favorable toxicity profile and early evidence of efficacy in patients. See related article by Marullo et al., p. 101.