Effect of Tandem Autologous Stem Cell Transplant vs Single Transplant on Event-Free Survival in Patients With High-Risk Neuroblastoma: A Randomized Clinical Trial.

IMPORTANCE Induction chemotherapy followed by high-dose therapy with autologous stem cell transplant and subsequent antidisialoganglioside antibody immunotherapy is standard of care for patients with high-risk neuroblastoma, but survival rate among these patients remains low. OBJECTIVE To determine if tandem autologous transplant improves event-free survival (EFS) compared with single transplant. DESIGN, SETTING, AND PARTICIPANTS Patients were enrolled in this randomized clinical trial from November 2007 to February 2012 at 142 Children's Oncology Group centers in the United States, Canada, Switzerland, Australia, and New Zealand. A total of 652 eligible patients aged 30 years or younger with protocol-defined high-risk neuroblastoma were enrolled and 355 were randomized. The final date of follow-up was June 29, 2017, and the data analyses cut-off date was June 30, 2017. INTERVENTIONS Patients were randomized to receive tandem transplant with thiotepa/cyclophosphamide followed by dose-reduced carboplatin/etoposide/melphalan (n = 176) or single transplant with carboplatin/etoposide/melphalan (n = 179). MAIN OUTCOMES AND MEASURES The primary outcome was EFS from randomization to the occurrence of the first event (relapse, progression, secondary malignancy, or death from any cause). The study was designed to test the 1-sided hypothesis of superiority of tandem transplant compared with single transplant. RESULTS Among the 652 eligible patients enrolled, 297 did not undergo randomization because they were nonrandomly assigned (n = 27), ineligible for randomization (n = 62), had no therapy (n = 1), or because of physician/parent preference (n = 207). Among 355 patients randomized (median diagnosis age, 36.1 months; 152 [42.8%] female), 297 patients (83.7%) completed the study and 21 (5.9%) were lost to follow-up after completing protocol therapy. Three-year EFS from the time of randomization was 61.6% (95% CI, 54.3%-68.9%) in the tandem transplant group and 48.4% (95% CI, 41.0%-55.7%) in the single transplant group (1-sided log-rank P = .006). The median (range) duration of follow-up after randomization for 181 patients without an event was 5.6 (0.6-8.9) years. The most common significant toxicities following tandem vs single transplant were mucosal (11.7% vs 15.4%) and infectious (17.9% vs 18.3%). CONCLUSIONS AND RELEVANCE Among patients aged 30 years or younger with high-risk neuroblastoma, tandem transplant resulted in a significantly better EFS than single transplant. However, because of the low randomization rate, the findings may not be representative of all patients with high-risk neuroblastoma.