Translational Oncology (Jan 2021)

Enhanced efficacy of JAK1 inhibitor with mTORC1/C2 targeting in smoldering/chronic adult T cell leukemia

  • Anusara Daenthanasanmak,
  • Yuquan Lin,
  • Meili Zhang,
  • Bonita R. Bryant,
  • Michael N. Petrus,
  • Richard N. Bamford,
  • Craig J. Thomas,
  • Milos D. Miljkovic,
  • Kevin C. Conlon,
  • Thomas A. Waldmann

Journal volume & issue
Vol. 14, no. 1
p. 100913

Abstract

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Adult T-cell leukemia (ATL) is an aggressive T-cell lymphoproliferative malignancy of regulatory T lymphocytes (Tregs), caused by human T-cell lymphotropic virus 1 (HTLV-1). Interleukin 2 receptor alpha (IL-2Rα) is expressed in the leukemic cells of smoldering/chronic ATL patients, leading to constitutive activation of the JAK/STAT pathway and spontaneous proliferation. The PI3K/AKT/mTOR pathway also plays a critical role in ATL cell survival and proliferation. We previously performed a high-throughput screen that demonstrated additive/synergistic activity of Ruxolitinib, a JAK1/2 inhibitor, with AZD8055, an mTORC1/C2 inhibitor. However, effects of unintended JAK2 inhibition with Ruxolitinib limits it therapeutic potential for ATL patients, which lead us to evaluate a JAK1-specific inhibitor. Here, we demonstrated that Upadacitinib, a JAK-1 inhibitor, inhibited the proliferation of cytokine-dependent ATL cell lines and the expression of p-STAT5. Combinations of Upadacitinib with either AZD8055 or Sapanisertib, mTORC1/C2 inhibitors, showed anti-proliferative effects against cytokine-dependent ATL cell lines and synergistic effect with reducing tumor growth in NSG mice bearing IL-2 transgenic tumors. Importantly, the combination of these two agents inhibited ex vivo spontaneous proliferation of ATL cells from patients with smoldering/chronic ATL. Combined targeting of JAK/STAT and PI3K/AKT/mTOR pathways represents a promising therapeutic intervention for patients with smoldering/chronic ATL.

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