Researchers affiliated with the Southwest Oncology Group (SWOG) reported that Camptosar® (irinotecan) plus Platinol® (cisplatin) did not demonstrate a survival improvement compared with VePesid® (etoposide)/cisplatin in the treatment of extensive-stage small cell lung cancer (SCLC). The SWOG researchers state that in North America, “etoposide remains the reference standard for treatment of SCLC.” These results were presented at the 2008 annual meeting of the American Society of Clinical Oncology.

Little progress has been made in terms of advancements of therapy for extensive-stage SCLC, with the reference chemotherapy regimen remaining VePesid/cisplatin. In 2002, a trial conducted by Japanese researchers reported that Camptosar/cisplatin produced a significant improvement in survival over the standard VePesid/cisplatin for extensive-stage SCLC. In light of these results, SWOG researchers conducted a confirmatory trial to validate these findings among patients in North America.

The trial included 671 patients with extensive SCLC who were randomized to receive Camptosar (60 mg/m2 at days one, eight, and 15) in addition to cisplatin (60 mg/ m2 on day one and then once every four weeks for a total four cycles), or receive etoposide (100 mg/ m2 at day one, two, and three) in addition to cisplatin )80 mg/ m2 at day one and then once a week for three weeks) for a maximum of four cycles. All patients had a performance status of 0-1 and had adequate hepatic, renal, and hematologic function.

• Median progression-free survival was 5.7 months for patients treated with Camptosar compared with 5.2 months for those treated with VePesid (P=0.07).
• Median overall survival was also not significantly different between the two groups: 9.9 months for the Camptosar group and 9.1 months for the VePesid group (P=0.71).

In the Japanese trial, medial overall survival was nearly 13 months for patients treated with Camptosar. Interestingly, toxicity profiles also differed between the Japanese and SWOG trials, with much lower rates of neutropenia and leucopenia reported in the SWOG trial.

• Rates of neutropenia were 32% for the Camptosar arm and 66% for the VePesid arm.
• Leucopenia was reported in 17% of patients treated with Camptosar and 33% of patients treated with VePesid.

Comments: These researchers concluded that “etoposide remains the reference standard for treatment of SCLC” in North America. Pharmacogenomic differences as well as the early stopping of the Japanese trial may have played a role in the different outcomes between the Japanese and SWOG trials.

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Reference: Natale, R et al. S0124: A randomized phase III trial comparing irinotecan/cisplatin (IP) with etoposide/cisplatin (EP) in patients (pts) with previously untreated extensive stage small cell lung cancer (E-SCLC). Proceedings from the 2008 annual meeting of the American Society of Clinical Oncology (ASCO). Abstract 7512.