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Biomarker-driven strategy for MCL1 inhibition in T-cell lymphomas

Raphael Koch, Amanda L. Christie, Jennifer L. Crombie, Adam C. Palmer, Deborah Plana, Kay Shigemori, Sara N. Morrow, Alexandria Van Scoyk, Wenchao Wu, Elizabeth A. Brem, J. Paul Secrist, Lisa Drew, Alwin Schuller, Justin Cidado, Anthony Letai and David M. Weinstock

Key points

  • We outline a biomarker-driven treatment strategy for targeting MCL1 in T-cell lymphomas.

  • AZD5991 shows promising activity as both a single agent and in combination with CHOP-based therapy.

Abstract

There is a pressing need for more effective therapies to treat patients with T-cell lymphomas (TCL), including first-line approaches that increase the response rate to CHOP chemotherapy. We characterized the mitochondrial apoptosis pathway in cell lines and patient-derived xenograft (PDX) models of TCL and assessed the in vitro efficacy of BH3 mimetics, including the BCL2 inhibitor venetoclax, the BCL2/BCL-xL inhibitor navitoclax and the novel MCL1 inhibitor AZD5991. The abundance of anti-apoptotic BCL2 family members based on immunoblotting or RNA transcript levels correlated poorly with the activity of BH3 mimetics. In contrast, the functional approach BH3 profiling reliably predicted sensitivity to BH3 mimetics in vitro and in vivo. We used BH3 profiling to select TCL PDXs that were dependent on MCL1. Mice xenografted with these PDXs and treated with AZD5991 had markedly improved survival. The combination of AZD5991 and CHOP achieved synergy based on survival improvement beyond a mathematical 'sum of benefits' model. Thus, MCL1 inhibition is a promising strategy as both a single agent and in combination with chemotherapy for patients with TCL and functional dependence on MCL1.

  • Submitted July 30, 2018.
  • Accepted November 26, 2018.