G. Ross

A Phase I Trial of a 5-Day Schedule of Intravenous Topotecan and Etoposide in Previously Untreated Patients with Small-Cell Lung Cancer

A phase I dose-escalation study was undertaken to determine the maximum tolerated dose of the intravenous combination of topotecan and etoposide in previously untreated patients with small-cell lung cancer. Nineteen patients were treated with 30-min infusions of topotecan (0.5 mg/m2/day for cohort 1; 0.75 mg/m2/day for cohort 2) followed by 1-hour infusions of a fixed daily dose of etoposide (60 mg/m2/day) for 5 consecutive days every 3 weeks. Patient cohort 1 (n = 7) received a total of 41 courses of chemotherapy. Grade 4 neutropenia occurred after 17% of the courses of therapy, and there was 1 episode of dose-limiting toxicity in this patient cohort. In patient cohort 2 (n = 12), a total of 64 courses of chemotherapy were administered. Grade 3 or 4 neutropenia occurred following 41 and 37% of the courses of therapy, respectively. Grade 3 thrombocytopenia occurred following 19% of the courses of therapy, and there were 3 episodes of dose-limiting toxicity in this patient cohort. There were no toxic deaths, and all nonhematologic toxicity (except hair loss) was ≤ grade 2. No further dose escalation was performed because of the degree of myelosuppression seen in patient cohort 2. All 19 patients were evaluable for response. Eighteen (95%) patients responded (14 partial responses and 4 complete responses) and the median survival was 10 months. This 5-day schedule of intravenous topotecan and etoposide administered sequentially on the same day is well tolerated, and the preliminary response rates were high in patients with previously untreated small-cell lung cancer.

Preliminary Results of Combined Therapy with Topotecan and Carboplatin in Advanced Non-Small-Cell Lung Cancer

Topotecan is a topoisomerase I inhibitor and an analogue of camptothecin with demonstrated activity in small-cell lung cancer. However, less is known about the potential role of topotecan in advanced non-small-cell lung cancer (NSCLC). Platinum-based combination therapy is currently recommended in NSCLC patients presenting with good performance status. Because topotecan demonstrates a novel mechanism of action, its investigation in platinum combinations is warranted. In phase I/II trials of topotecan given as part of a cisplatin-based regimen, significant antitumor activity has been observed, providing the rationale for conducting further studies aimed at assessing survival benefit. However, this combination exhibits sequence dependence, with increasing hematologic toxicity observed when cisplatin is administered on day 1 of a 5-day topotecan course. Cisplatin has been associated with dose-limiting nonhematologic toxicities. Carboplatin exhibits a different toxicity profile compared with cisplatin, which makes it an attractive agent to study in combination. A hypothesis can be made that carboplatin in combination with newer agents such as topotecan might compare favorably with classic cisplatin-based regimens, particularly with respect to efficacy:toxicity ratio. Therefore, a phase II study was initiated to determine the efficacy, toxicity, and safety of carboplatin-topotecan combination in advanced NSCLC. Preliminary results reported here show that topotecan with carboplatin is generally well tolerated with manageable hematologic toxicity. Indirect comparison with cisplatin-topotecan combination suggests a lower incidence of dose-limiting nonhematologic toxicity. Whether or not the carboplatin-topotecan regimen is able to offer tumor response and survival benefit comparable to those observed with cisplatin-based combinations remains to be established.