Warren Chow, MD

WARREN CHOW, MD, a sarcoma specialist at City of Hope, Duarte, California, said maintenance therapy has not traditionally been used in the treatment of rhabdomyosarcoma; therefore, the findings represent “a paradigm shift.” 

Although the RMS2005 Maintenance study established a new standard of care for European oncologists, the findings are not yet relevant to clinical practice in the United States, Dr. Chow, serving as an ASCO expert during a press briefing, pointed out. “There are differences in how rhabdomyosarcoma is treated here,” he explained. Specifically, the protocol of the Children’s Oncology Group (COG) includes combinations of vincristine, cyclophosphamide, dactinomycin, and irinotecan. 

“These results will need to be tested with a U.S.-based protocol before becoming a standard in this country,” he maintained. “We also need to determine whether the results are applicable to high-risk patients older than 21 years of age. Despite these caveats, this is the first significant treatment advance in this rare cancer in more than 20 years.” 

Results Attributed to Maintenance Itself or Duration of Therapy? 

Douglas S. Hawkins, MD

DOUGLAS S. HAWKINS, MD, Division Chief and Professor of Pediatrics in the Hematology/Oncology Division of Seattle Children’s Hospital, was the study’s invited discussant. He noted that the RMS2005 Maintenance study is just the third positive randomized trial to be reported in pediatric rhabdomyosarcoma. 

The positive results, in his opinion, were most likely attributable to the addition of vinorelbine or the longer duration of therapy (51 weeks), which brought the regimen in line with the 42-week COG protocol. 

“One could imagine that we could compare the COG and European Paediatric Soft Tissue Sarcoma Study Group strategies to try to tease out whether it’s really the duration of the therapy rather than maintenance itself that led to the improved overall survival in this study,” Dr. Hawkins concluded. ■

DISCLOSURE: Dr. Chow is on the speakers bureau for Novartis, the advisory board for GlaxoSmithKline, and on the data safety monitoring committee for Advenchen. Dr. Hawkins has received travel expenses from Bayer, Bristol-Myers Squibb, Celgene, and Loxo Oncology.