Gemcitabine is a new
deoxycytidine derivative that shows a distinguishing, potent antitumor activity against various human
tumor lines transplanted to nude mice. We have investigated the antitumor activity of
gemcitabine combined with
cisplatin (CDDP) or
vindesine (VDS) using a
lung cancer line,
H-74, that was insensitive to almost all
antitumor drugs and relatively insensitive to
gemcitabine. We found that the antitumor effects of
gemcitabine combined with CDDP or VDS were more potent and lasted longer than that of each
drug alone, without an increase in side effects such as
body weight loss. In this study, the antitumor activity of combined
gemcitabine with topotecin (CPT-11) was evaluated using a similar method for 8 weeks, including a 4-week treatment period and a subsequent 4-week
drug-free period, with reference to
tumor growth inhibition rate, histological changes, and side effects. The treatment combining
gemcitabine with
CPT-11 administered at each 1/2 MTD showed an additive effect at 4 and 8 weeks after start of administration. Furthermore, no remarkable side effects were observed. Since these study results demonstrated that
gemcitabine combined with
CPT-11 increased and prolonged the antitumor activity without increasing side effects such as
body weight loss, it is expected that
CPT-11 could be one of the useful drugs used in combination with
gemcitabine for
lung cancer therapy.