Taxol is a novel antineoplastic agent that has demonstrated impressive clinical activity in breast, ovarian, lung, and head and neck cancers. This broad antitumor activity of taxol in cisplatin-sensitive tumors suggests that the combination of taxol and cisplatin may become one of the most commonly used taxol-based chemotherapeutic regimen in the treatment of solid tumors. Both taxol and cisplatin, however, are neurotoxic. To study the neurotoxic effects of these two agents when used in combination, we prospectively evaluated neurological function at baseline, during, and following treatment, in 21 cancer patients treated with taxol (135-350 mg/m2), cisplatin (75-100 mg/m2), and granulocyte-colony stimulating factor (5 micrograms/kg). Twenty of the 21 patients (95%) developed a sensory-motor neuropathy 1 to 21 weeks after the initiation of therapy, that was progressive with each additional course of chemotherapy. The neuropathy was symmetrical, length dependent, axonal in nature by physiological studies, and more pronounced in those patients who received higher doses of taxol. The neuropathy appeared earlier and at lower taxol doses in those patients with preexisting neuropathies. We conclude that sensory-motor neuropathy is a frequent dose-dependent toxicity of combined cisplatin and taxol use. Peripheral neuropathy is likely to become the major dose-limiting toxicity of taxol-cisplatin combination chemotherapy when higher doses of these agents are administered with granulocyte-colony stimulating factor.

Neutropenia is the dose-limiting toxicity, and 1.5 mg/m2 is the recommended starting dose of topotecan for both minimally and heavily pretreated patients in future phase II trials, with escalation to 2.0 mg/m2 if treatment is well tolerated. Non-small-cell lung and platinum-refractory ovarian carcinomas should be among those evaluated in phase II trials of topotecan.

Untreated and minimally pretreated solid tumor patients received alternating sequences of taxol and cisplatin. Sequential dose escalation of each agent using taxol doses of 110 or 135 mg/m2 and cisplatin doses of 50 or 75 mg/m2 resulted in four dosage permutations that induced grades 3 and 4 neutropenia in 72% to 84% and 50% to 53% of courses, respectively. Neutropenia was brief, and hospitalization for neutropenia and fever was required in 13% to 24% of courses. However, further escalation of taxol to 170 or 200 mg/m2 induced grade 4 neutropenia in 79% to 82% of courses. At the highest taxol-cisplatin dose level (200 mg/m2 to 75 mg/m2), the mean neutrophil count nadir was 98/microL, and hospitalization for neutropenia and fever was required in 64% of courses. The sequence of cisplatin before taxol, which has less antitumor activity in vitro, induced more profound neutropenia than the alternate sequence. Pharmacologic studies indicated that this difference was probably due to 25% lower taxol clearance rates when cisplatin preceded taxol. Although neurotoxicity was initially thought to be a potentially serious effect of the combination, mild to modest neurotoxicity occurred in only 27% of patients. Adverse effects also included myalgias, alopecia, vomiting, diarrhea, bradycardia, and asymptomatic ventricular tachycardia. Objective responses were noted in melanoma, as well as non-small-cell lung, ovarian, breast, head and neck, colon, and pancreatic carcinomas. Based on these results, the sequence of taxol before cisplatin at doses of 135 and 75 mg/m2, respectively, is recommended for phase II/III trials, with escalation of taxol to 170 mg/m2 if treatment is well tolerated.

Despite increasing evidence of benefit from adjuvant chemotherapy, older women with breast cancer are commonly given less aggressive treatment than younger patients. Conflicting prior data regarding age-related toxicity prompted this prospective study. Forty-four women (aged 35-79 years) with early-stage breast cancer were treated with four cycles of adjuvant therapy with doxorubicin 60 mg/m2 i.v. and cyclophosphamide 600 mg/m2 i.v. every 21 days. They were monitored for myelosuppression, cardiotoxicity, and decrease in quality of life. Pharmacokinetics were analyzed using cycle 1 plasma samples. Bone marrow granulocyte and macrophage colony-forming units (CFU-GM) were assayed in vitro for dose response to 4-hydroperoxycyclophosphamide and doxorubicin before cycle 1. There was moderate evidence of age-related decrease in nadir absolute neutrophil count (ANC) when age was viewed as a continuous variable. On average there was a 10/microliter drop in cycle 1 nadir ANC for every year increase in age (p = 0.02). However, when age was viewed as a categorical variable (age < 65 vs. > or = 65 years), a similar proportion of women in each group reached an ANC < 100 (18% vs. 19%). Neither neutropenic complications, alteration in cardiac function, nor change in quality of life scores were significantly age related (p > 0.12). Pharmacokinetic analyses did not demonstrate age-related differences in the clearance of either doxorubicin or cyclophosphamide (p > 0.8). Pharmacodynamic analysis of individual patient bone marrow progenitor cell sensitivity did not reveal any correlation with age (p > 0.48). In women undergoing adjuvant therapy for breast cancer, no clinically significant age-related trends in toxicity were observed. These data suggest that older age alone should not exclude patients from receiving adjuvant therapy with doxorubicin and cyclophosphamide.