Hawkins DS, et al. - Researchers sought to improve the outcome of patients with intermediate-risk rhabdomyosarcoma (RMS) by substituting vincristine and irinotecan (VI) for half of vincristine, dactinomycin, and cyclophosphamide (VAC) courses. For patients with intermediate-risk RMS, the addition of VI to VAC did not improve EFS or OS. Less hematologic toxicity and a lower cumulative cyclophosphamide dose were seen in VAC/VI, thereby, making VAC/VI an alternative standard therapy for intermediate-risk RMS.

Methods

• Authors randomly assigned the patients at study entry to either VAC (cumulative cyclophosphamide dose, 16.8 g/m²) or VAC/VI (cumulative cyclophosphamide dose, 8.4 g/m²) for 42 weeks of therapy.
• At week 4, the radiation therapy started, with individualized local control plans permitted for patients younger than 24 months.
• Event-free survival (EFS) was the primary study end point.
• In order to detect an improved long-term EFS from 65% (with VAC) to 76% (with VAC/VI), the study design had an 80% power (5% one-sided α-level).

Results

• As per data, a total of 448 eligible patients were enrolled in the study.
• Findings suggested that at a median follow-up of 4.8 years, the 4-year EFS was 63% with VAC and 59% with VAC/VI (P=.51), and 4-year overall survival was 73% for VAC and 72% for VAC/VI (P=.80).
• Results did not demonstrated any difference in the outcome by treatment arm within the ARMS and ERMS subgroups.
• With VAC/VI therapy, severe hematologic toxicity was less common.