Co-targeting BCL-XL and MCL-1 with DT2216 and AZD8055 synergistically inhibit small-cell lung cancer growth without causing on-target toxicities in mice

Sajid Khan, Patrick Kellish, Nick Connis, Dinesh Thummuri, Janet Wiegand, Peiyi Zhang, Xuan Zhang, Vivekananda Budamagunta, Nan Hua, Yang Yang, Umasankar De, Lingtao Jin, Weizhou Zhang, Guangrong Zheng, Robert Hromas, Christine Hann, Maria Zajac-Kaye, Frederic J. Kaye, Daohong Zhou

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Small-cell lung cancer (SCLC) is an aggressive malignancy with limited therapeutic options. The dismal prognosis in SCLC is in part associated with an upregulation of BCL-2 family anti-apoptotic proteins, including BCL-XL and MCL-1. Unfortunately, the currently available inhibitors of BCL-2 family anti-apoptotic proteins, except BCL-2 inhibitors, are not clinically relevant because of various on-target toxicities. We, therefore, aimed to develop an effective and safe strategy targeting these anti-apoptotic proteins with DT2216 (our platelet-sparing BCL-XL degrader) and AZD8055 (an mTOR inhibitor) to avoid associated on-target toxicities while synergistically optimizing tumor response. Through BH3 mimetic screening, we identified a subset of SCLC cell lines that is co-dependent on BCL-XL and MCL-1. After screening inhibitors of selected tumorigenic pathways, we found that AZD8055 selectively downregulates MCL-1 in SCLC cells and its combination with DT2216 synergistically killed BCL-XL/MCL-1 co-dependent SCLC cells, but not normal cells. Mechanistically, the combination caused BCL-XL degradation and suppression of MCL-1 expression, and thus disrupted MCL-1 interaction with BIM leading to an enhanced apoptotic induction. In vivo, the DT2216 + AZD8055 combination significantly inhibited the growth of cell line-derived and patient-derived xenografts and reduced tumor burden accompanied by increased survival in a genetically engineered mouse model of SCLC without causing appreciable thrombocytopenia or other normal tissue injuries. Thus, these preclinical findings lay a strong foundation for future clinical studies to test DT2216 + mTOR inhibitor combinations in a subset of SCLC patients whose tumors are co-driven by BCL-XL and MCL-1.

Original languageEnglish (US)
Article number1
JournalCell Death Discovery
Issue number1
StatePublished - Dec 2023

ASJC Scopus subject areas

  • Cellular and Molecular Neuroscience
  • Cancer Research
  • Cell Biology
  • Immunology


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