CXCL12/CXCR4 signaling, being important in the homing of
cancer cells to lungs, bone and other organs, is a promising therapeutic target. Our purpose was to determine whether a
peptide-based antagonist of CXCR4 would reduce primary
tumor growth and/or
metastasis in a preclinical mouse model of
inflammatory breast cancer. We improved an existing model of
inflammatory breast cancer for this study by
luciferase transfection of SUM149 cells and the monitoring of such cells in mice by imaging and the
luciferase assay. We implanted 2 x 10(6) SUM49-Luc cells along with
matrigel into the left thoracic mammary fat pad of nude mice to produce
tumors. Our mouse model exhibited important features of
inflammatory breast cancer, namely, aggressive local disease, local
metastases and distant
metastases. To evaluate the efficacy of a CXCR4 antagonist
CTCE-9908, by itself or in combination with
paclitaxel, we treated groups of ten mice each with
CTCE-9908 (25 mg/kg, injected subcutaneously 5 days/week), control
peptide SC-9908,
paclitaxel (10 mg/kg, injected subcutaneously twice a week), and
CTCE-9908 plus
paclitaxel concurrently. We assessed all mice weekly by whole-body
luciferase imaging to quantify relative primary
tumor burden and distant
metastases. At the end of the experiment, we quantified primary
tumors by weight and lung
metastases by
luciferase activity assay on tissue lysates.
Paclitaxel, a known chemotherapeutic, inhibited primary
tumor growth in our model (P < 0.05).
CTCE-9908 did not significantly inhibit primary
tumor growth or lung
metastases as compared to control groups, without or with
paclitaxel (P > 0.05). However,
CTCE-9908 as a single
therapy inhibited organ-specific
metastasis to leg (P < 0.05 by chi-squared test and by two-sample t-test).