Fa. Holmes et al., SECONDARY DRUG-RESISTANCE IN BREAST-CANCER - FAILURE TO REVERSE WITH ORAL NIFEDIPINE, International journal of cancer, 73(2), 1997, pp. 184-186
We tested the efficacy of nifedipine to reverse acquired resistance to
chemotherapy regimens containing doxorubicin or vinblastine or both i
n 12 patients with metastatic breast cancer, Ail patients had been rec
eiving one or both of these drugs, had had a prior partial response (m
edian duration 5 months, range 2-10) and subsequently progressed. Imme
diately after drug resistance was documented by tumor progression, eli
gible patients with measurable or evaluable disease were treated with
nifedipine beginning 3 days before restarting the same chemotherapy. T
he initial dose of nifedipine was 20 mg TID, escalating daily to 40 mg
TID on day 3 if the patient had no serious side effects, Nifedipine w
as continued at the highest tolerable dose during and for 2 days after
completion of the chemotherapy, Most patients had less than or equal
to 2 prior chemotherapy regimens and a median Zubrod performance statu
s of 1. Twelve patients received a total of 23 courses preceded by nif
edipine. No objective tumor responses were observed, The expected toxi
c effects attributable to nifedipine occurred, but nifedipine did not
increase the toxicity caused by the chemotherapy, Nifedipine, given in
this dose and schedule, did not reverse acquired drug resistance in p
atients with breast cancer. (C) 1997 Wiley-Liss, Inc.