Journal
CLINICAL CANCER RESEARCH
Volume 18, Issue 24, Pages 6668-6678Publisher
AMER ASSOC CANCER RESEARCH
DOI: 10.1158/1078-0432.CCR-12-0984
Keywords
-
Categories
Funding
- NIH [R01 CA113851, 5P30CA016087-32]
- Chemotherapy Foundation
- NCI [K23 CA125205]
- Molecular Oncology and Immunology Training [T32 CA009161-33-34]
Ask authors/readers for more resources
Purpose: This study tested the hypothesis that topical Toll-like receptor (TLR) 7 agonist imiquimod promotes antitumor immunity and synergizes with other treatments in a model of skin-involving breast cancer. Experimental Design: TSA mouse breast carcinoma cells were injected s.c. into syngeneic mice. Imiquimod 5% or placebo cream was applied topically on the shaved skin overlying tumors three times/wk. In some experiments, local ionizing radiation therapy (RT) was delivered to the tumor in three fractions of 8 Gy, given on consecutive days. Cyclophosphamide was given intraperitoneally (i.p.) in one dose of 2 mg/mouse. Mice were followed for tumor growth and survival. Results: Treatment with imiquimod significantly inhibited tumor growth, an effect that was associated with increased tumor infiltration by CD11c(+), CD4(+), and CD8(+) cells, and abolished by depletion of CD8(+) cells. Administration of imiquimod in combination with RT enhanced significantly tumor response compared with either treatment alone (P < 0.005), and 11% to 66% of irradiated tumors completely regressed. Importantly, the addition of topical imiquimod also resulted in growth inhibition of a secondary tumor outside of the radiation field. Low-dose cyclophosphamide given before start of treatment with imiquimod and RT further improved tumor inhibition and reduced tumor recurrence. Mice that remained tumor-free rejected a tumorigenic inoculum of TSA cells, showing long-term immunologic memory. Conclusions: Topical imiquimod inhibits tumor growth and synergizes with RT. Addition of cyclophosphamide further increases the therapeutic effect and induces protective immunologic memory, suggesting that this combination is a promising strategy for cutaneous breast cancer metastases. Clin Cancer Res; 18(24); 6668-78. (C) 2012 AACR.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available