Cutaneous T-Cell Lymphoma PDX Drug Screening Platform Identifies Cooperation between Inhibitions of PI3Kα/δ and HDAC

J Invest Dermatol. 2021 Feb;141(2):364-373. doi: 10.1016/j.jid.2020.05.110. Epub 2020 Jun 27.


Cutaneous T-cell lymphoma is a form of non-Hodgkin lymphoma that manifests initially in the skin and disseminates systemically as the disease progresses. Mycosis fungoides and Sézary syndrome are the most common subtypes of cutaneous T-cell lymphoma. Advanced mycosis fungoides and Sézary syndrome are life threatening with few treatment options. We searched for new agents by high-throughput screening of selected targeted compounds and identified high-value targets, including phosphatidylinositol 3-kinase (PI3K) and cyclin-dependent kinases. To validate these hits from the screen, we developed patient-derived xenograft mouse models that recapitulated the cardinal features of mycosis fungoides and Sézary syndrome and maintained histologic and molecular characteristics of their clinical counterparts. Importantly, we established a blood-based biomarker assay using tumor cell-free DNA to measure systemic tumor burden longitudinally in living mice during drug therapy. A PI3K inhibitor, BKM120, was tested in our patient-derived xenograft model leading to disease attenuation and prolonged survival. Isoform-specific small interfering RNA knockdowns and isoform-selective PI3K inhibitors identified PI3K-δ as required for tumor proliferation. Additional studies showed a synergistic combination of PI3K-α/δ inhibitors with histone deacetylase inhibitors. The strong preclinical efficacy of this potent combination against multiple patient-derived xenograft models makes it an excellent candidate for further clinical development.

Publication types

  • Observational Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aminopyridines / pharmacology
  • Aminopyridines / therapeutic use
  • Animals
  • Antineoplastic Combined Chemotherapy Protocols / pharmacology*
  • Antineoplastic Combined Chemotherapy Protocols / therapeutic use
  • Cell Line, Tumor
  • Circulating Tumor DNA / blood
  • Class I Phosphatidylinositol 3-Kinases / antagonists & inhibitors
  • Class I Phosphatidylinositol 3-Kinases / genetics
  • Class I Phosphatidylinositol 3-Kinases / metabolism
  • Drug Synergism
  • Female
  • Gene Knockdown Techniques
  • High-Throughput Screening Assays
  • Histone Deacetylase Inhibitors / pharmacology*
  • Histone Deacetylase Inhibitors / therapeutic use
  • Histone Deacetylases / metabolism
  • Humans
  • Lymphoma, T-Cell, Cutaneous / blood
  • Lymphoma, T-Cell, Cutaneous / diagnosis
  • Lymphoma, T-Cell, Cutaneous / drug therapy*
  • Lymphoma, T-Cell, Cutaneous / pathology
  • Mice
  • Morpholines / pharmacology
  • Morpholines / therapeutic use
  • Protein Kinase Inhibitors / pharmacology*
  • Protein Kinase Inhibitors / therapeutic use
  • Skin / pathology
  • Skin Neoplasms / blood
  • Skin Neoplasms / diagnosis
  • Skin Neoplasms / drug therapy*
  • Skin Neoplasms / pathology
  • Tumor Burden / drug effects
  • Xenograft Model Antitumor Assays


  • Aminopyridines
  • Circulating Tumor DNA
  • Histone Deacetylase Inhibitors
  • Morpholines
  • NVP-BKM120
  • Protein Kinase Inhibitors
  • Class I Phosphatidylinositol 3-Kinases
  • PIK3CA protein, human
  • PIK3CD protein, human
  • Histone Deacetylases