Metronomic Maintenance Therapy Significantly Improves Overall Survival in Rhabdomyosarcoma

CHICAGO—Adding maintenance therapy after completing standard therapy may lead to significantly improved rates of overall survival (OS) among patients with high-risk (HR) rhabdomyosarcoma (RMS), according to a presentation in the Plenary Session at the American Society of Clinical Oncology 2018 Annual Meeting on Sunday, June 3.¹

Although complete remission rates are high among patients with RMS, anywhere between 20% and 30% of these patients will relapse and have poor outcomes with salvage therapy. Researchers sought to determine if maintenance treatment with metronomic chemotherapy would improve survival outcomes.

For this study, researchers enrolled 670 patients between the ages of 6 months and 21 years with nonmetastatic alveolar RMS (ARMS), or incompletely resected embryonal RMS (ERMS) in an unfavorable primary site and/or N1, in complete remission upon the completion of standard therapy (9 cycles of ifosfamide, vincristine, actinomycin D with or without doxorubicin, surgery, with or without radiotherapy). Patients were randomly assigned to stop all treatment (control arm) or receive maintenance therapy with intravenous (IV) vinorelbine 25 mg/m² and oral cyclophosphamide 25 mg/m².

Of the 371 patients found to be eligible for the study, 186 were assigned to the control arm and 185 were assigned to the maintenance arm. Baseline clinical characteristics were well balanced between the 2 arms.

After a median follow-up of 5 years among surviving patients, the 3-year event-free survival (EFS) was 78.4% (95% CI, 71.5-83.8) among patients receiving maintenance chemotherapy compared with  72.3% (95% CI, 65.0-78.3) among patients who discontinued treatment (P = .061).

The 5-year OS rate was 87.3% (95% CI, 81.2-91.6) and 77.4% (95% CI, 70.1-83.1) among patients in the maintenance therapy arm and the control arm, respectively (P = .011).

Grade 3 to 4 febrile neutropenia and neurotoxicity were observed in 25% and 1.1% of patients in the maintenance arm, respectively, but toxicity was noted to be manageable.

The authors concluded that “the addition of maintenance after standard treatment significantly improves OS in HR RMS patients and support its inclusion in future European Paediatric Soft Tissue Sarcoma Study Group (EpSSG) trials.”

Read more of Cancer Therapy Advisor‘s coverage of the American Society of Clinical Oncology (ASCO) 2018 meeting by visiting the conference page.

Reference

1. Bisogno G, De Salvo GL, Bergeron C, et al. Maintenance low-dose chemotherapy in patients with high-risk (HR) rhabdomyosarcoma (RMS): A report from the European Paediatric Soft Tissue Sarcoma Study Group (EpSSG). Late breaking abstract presentation at: 2018 ASCO Annual Meeting; June 1-5, 2018; Chicago, IL.