Combination Therapy of Capecitabine with Cyclophosphamide as a Second-Line Treatment after Failure of Paclitaxel plus Bevacizumab Treatment in a Human Triple Negative Breast Cancer Xenograft Model ()
ABSTRACT
We examined the antitumor efficacy of
the capecitabine (CAPE) plus cyclophosphamide (CPA) combination as a 2nd-line
therapy after paclitaxel (PTX) plus bevacizumab (BEV) treatment in a xenograft
model of human triple negative breast cancer (TNBC) cell line, MX-1. After
tumor growth was confirmed, PTX (20 mg/kg; i.v.) + BEV (5 mg/kg; i.p.) treatment was started (Day 1). Each agent was administered
once a week for 5 weeks and tumor regression was observed for at least the
first 3 weeks. For 2nd-line treatment, we selected mice in which the
tumor volume had increased from day 29 to day 36 and was within 130 - 250 mm3 on day 36. After randomization of mice selected
on day 36, CPA (10 mg/kg; p.o.) and
CAPE (539 mg/kg; p.o.) were
administered daily for 14 days (days 36 - 49), followed by cessation of the
drugs for 1 week. The tumor growth on day 57 was significantly suppressed in
the CPA, CAPE and CAPE + CPA groups as compared with the
control group (p < 0.05). Furthermore, the antitumor activity on day 57 of
CAPE + CPA was significantly stronger than
that of CPA or CAPE alone (p < 0.05). The thymidine phosphorylase (TP) level
in tumor tissue was evaluated by immunohistochemistry on day 50, and was
significantly higher in the CPA group than those in the control group (p <
0.05). Upregulation of TP in tumor tissues by CPA treatment would increase the
5-FU level in tumor tissues treated with CAPE. This would explain the possible
mechanism that made CAPE + CPA superior to
CAPE alone in the 2nd-line treatment. Our preclinical results
suggest that the CAPE + CPA combination therapy may be effective as 2nd-line therapy
after disease progression in PTX + BEV 1st-line
treatment for TNBC patients.
Share and Cite:
M. Yanagisawa, K. Yorozu, M. Kurasawa, Y. Moriya and N. Harada, "Combination Therapy of Capecitabine with Cyclophosphamide as a Second-Line Treatment after Failure of Paclitaxel plus Bevacizumab Treatment in a Human Triple Negative Breast Cancer Xenograft Model,"
Journal of Cancer Therapy, Vol. 4 No. 7, 2013, pp. 1236-1241. doi:
10.4236/jct.2013.47144.
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