Intensive Chemo Plus RT Improves EFS in High-Risk Rhabdomyosarcoma

Pediatric patients with metastatic rhabdomyosarcoma with 1 or no Oberlin risk factor had an improved 3-year event-free survival of 69% on the COG ARST0431 regimen compared with a historical cohort of patients, a new study published online ahead of print in the Journal of Clinical Oncology has shown.¹

Because most patients with metastatic rhabdomyosarcoma have an estimated long-term event-free survival of less than 20%, researchers in the Children’s Oncology Group sought to improve outcomes of patients with this type of metastatic sarcoma through dose intensification with interval compression, use of the most active agents, and use of irinotecan as a radiation sensitizer.

For the study, researchers enrolled 109 patients with metastatic rhabdomyosarcoma. Patients received blocks of therapy with vincristine plus irinotecan during weeks 1 to 6, 20 to 25, and 47 to 52, interval compression vincristine plus doxorubicin and cyclophosphamide alternating with etoposide and ifosfamide during weeks 7 to 19 and 26 to 34, and vincristine, dactinomycin, and cyclophosphamide during weeks 38 to 46.

Patients also received radiation therapy to the primary site at weeks 20 to 25, but were eligible to receive it at weeks 1 to 6 for intracranial or paraspinal extension and weeks 47 to 52 for extensive metastatic sites.

Results showed during a median follow-up of 3.8 years, the 3-year event-free survival for all patients was 38% (95% CI, 29 – 48). Researchers found that patients with 1 or no Oberlin risk factor (age > 10 years or < 1 year, unfavorable primary site of disease, 3 or more metastatic sites, and bone or bone marrow involvement) had a 3-year event-free survival of 69% (95% CI, 52 -82), while high-risk patients with 2 or more Oberlin risk factors had a 3-year event-free survival of 20% (95% CI, 11 -30).

In regard to safety, toxicity was similar to that of previously reported studies in patients with rhabdomyosarcoma.

“Those with 2 or more risk factors have a dismal prognosis, and new approaches are needed for this very-high-risk group,” the authors concluded.

Reference

1. Weigel BJ, Lyden E, Anderson JR, et al. Intensive multiagent therapy, including dose-compressed cycles of ifosfamide/etoposide and vincristine/doxorubicin/cyclophosphamide, irinotecan, and radiation, in patients with high-risk rhabdomyosarcoma: a report from the Children’s Oncology Group [published online ahead of print October 26, 2015]. J Clin Oncol. doi: 10.1200/JCO.2015.63.4048.