title: Metronomic cyclophosphamide activation of anti-tumor immunity: tumor model, mouse host, and drug schedule dependence of gene responses and their upstream regulators.
abstract: Cyclophosphamide (CPA) can activate immunogenic tumor cell death, which induces immune-based tumor ablation and long-term anti-tumor immunity in a syngeneic C57BL/6 (B6) mouse GL261 glioma model when CPA is given on a 6-day repeating metronomic schedule (CPA/6d). In contrast, we find that two other syngeneic B6 mouse tumors, LLC lung carcinoma and B16F10 melanoma, do not exhibit these drug-induced immune responses despite their intrinsic sensitivity to CPA cytotoxicity.
  
  
  
  To elucidate underlying mechanisms, we investigated gene expression and molecular pathway changes associated with the disparate immune responsiveness of these tumors to CPA/6d treatment.
  
  
  
  Global transcriptome analysis indicated substantial elevation of basal GL261 immune infiltration and strong CPA/6d activation of GL261 immune stimulatory pathways and their upstream regulators, but without preferential depletion of negative immune regulators compared to LLC and B16F10 tumors. In LLC tumors, where CPA/6d treatment is shown to be anti-angiogenic, CPA/6d suppressed VEGFA target genes and down regulated cell adhesion and leukocyte transendothelial migration genes. In GL261 tumors implanted in adaptive immune-deficient scid mice, where CPA/6d-induced GL261 regression is incomplete and late tumor growth rebound can occur, T cell receptor signaling and certain cytokine-cytokine receptor responses seen in B6 mice were deficient. Extending the CPA treatment interval from 6 to 9 days (CPA/9d) - which results in a strong but transient natural killer cell response followed by early tumor growth rebound - induced fewer cytokines and increased expression of drug metabolism genes.
  
  
  
  These findings elucidate molecular response pathways activated by intermittent metronomic CPA treatment and identify deficiencies that characterize immune-unresponsive tumor models and drug schedules.
authors: Division of Cell and Molecular Biology, Department of Biology and Bioinformatics Program, Boston University, 5 Cummington Mall, Boston, MA, 02215, USA.
authors: Junjie
authors: J
authors: Wu
authors: Division of Cell and Molecular Biology, Department of Biology and Bioinformatics Program, Boston University, 5 Cummington Mall, Boston, MA, 02215, USA.
authors: Marie
authors: M
authors: Jordan
authors: Division of Cell and Molecular Biology, Department of Biology and Bioinformatics Program, Boston University, 5 Cummington Mall, Boston, MA, 02215, USA. djw@bu.edu.
authors: David J
authors: 0000-0001-7982-9206
authors: DJ
authors: Waxman
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage*; D059250:Administration, Metronomic; D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000008:administration & dosage*; D001932:Brain Neoplasms / Q000188:drug therapy* / Q000276:immunology / Q000378:metabolism; D045744:Cell Line, Tumor; D003520:Cyclophosphamide / Q000008:administration & dosage*; D019008:Drug Resistance, Neoplasm; D004354:Drug Screening Assays, Antitumor; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D005910:Glioma / Q000188:drug therapy* / Q000276:immunology / Q000378:metabolism; D007113:Immunity, Innate / Q000187:drug effects; D008297:Male; D008810:Mice, Inbred C57BL; D016513:Mice, SCID; D009368:Neoplasm Transplantation; D011401:Promoter Regions, Genetic
chemical_list: D000276:Adjuvants, Immunologic; D018906:Antineoplastic Agents, Alkylating; D003520:Cyclophosphamide
keywords: Cd8+ T cells; Drug schedule; Immune responsiveness; Metronomic cyclophosphamide; NK cells; RNA-seq; Upstream regulator