CHICAGO – More children treated for high-risk neuroblastoma who received a second autologous stem cell transplant in consolidation after induction chemotherapy were alive after 3 years compared with children getting a single transplant, Dr. Julie R. Park reported at the annual meeting of the American Society of Clinical Oncology.
Neuroblastoma (NB) is the most common extracranial tumor of childhood and arises in the sympathetic nervous system of very young children. Fewer than 50% of children with high-risk NB survive 5 years following today’s multiagent, aggressive therapy. Single autologous hematopoietic stem cell transplant (ASCT) has improved outcomes, and in pilot studies, tandem ASCT appeared tolerable with better efficacy as consolidation therapy for high-risk NB.
The present trial enrolled 665 patients (mean age 3.1 years), who received an induction regimen of six cycles of chemotherapy, with harvest of peripheral blood stem cells after the first two cycles and surgery after five cycles. Patients with adequate stem cell collection, adequate organ function, and no evidence of disease progression were randomized to either standard therapy with a single ASCT with carboplatin, etoposide, melphalan and local radiotherapy (n = 179); or to a double (tandem) ASCT with cyclophosphamide and thiotepa prior to the first ASCT followed 6 weeks later by a dose-modified regimen of carboplatin, etoposide, melphalan and radiotherapy prior to a second ASCT (n = 176). The two transplants were separated by 6-8 weeks.
About 70% of patients in each arm received dinutuximab plus cytokine immunotherapy after their transplants. Dinutuximab is an antibody directed against GD2, an antigen present on neuroblastoma cells. About 38% of patients had high-risk tumors based on the presence of MYCN gene amplification.
The children who were randomized to receive a tandem transplant had a statistically significant, improved event-free survival, with a 3-year event-free survival of 61%, compared to those children receiving a single transplant, with a 3-year event-free survival of 48% (P = .0081), reported Dr. Park, professor of pediatrics at the University of Washington, Seattle.
Three-year overall survival did not differ between the two groups, at 74% for the tandem transplant group and 69% for the single transplant group (P = .185). The study was powered to see a difference in event-free survival, and the study was probably not long enough to detect a difference in overall survival, Dr. Park said.
Anti-GD2 immunotherapy improved both event-free and overall survival for both the tandem and single ASCT groups. At 3 years from the time of the patients’ receiving immunotherapy, event-free survival was 73.7% and 56%, respectively (P = .0033), and overall survival was 83.7% and 74.4% (P = .0322), respectively.
The benefit of tandem transplant occurred without an increase in toxicity or regimen-related mortality. The rates of severe toxicities were similar in the two arms. Two patients receiving a tandem ASCT died, compared with eight receiving a single ASCT.
“This finding will change the way we treat children with high-risk neuroblastoma in North America, which still claims many young lives and is in urgent need of better treatments,” Dr. Park said in a press release.
Dr. Park noted that most NB recurrences happen within 2-3 years from diagnosis and that patients who have not had a recurrence by 3 years have a better chance of long-term survival. Patients in this study will continue to be followed for 10 years.
Dr. Park disclosed ties with Roche. Dr. Hunger reported ties with Merck, Sigma Tau, Jazz Pharmaceuticals, and Spectrum Pharmaceuticals.