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10004 Background: Post-consolidation anti-GD2 antibody-based immunotherapy has improved survival for newly diagnosed patients (pts) with high-risk neuroblastoma (HRNBL). However, nearly half of newly diagnosed pts relapse. Based upon the efficacy of anti-GD2 antibody dinutuximab given with chemotherapy (chemoimmunotherapy) in the relapse setting, we hypothesized that post-consolidation chemoimmunotherapy may further improve frontline outcomes. ANBL19P1 first assessed the feasibility of delivering chemoimmunotherapy after tandem high-dose chemotherapy with autologous stem cell transplant (ASCT). Methods: Pts <31 years old with HRNBL who received 4-6 cycles of Induction chemotherapy +/- up to 4 cycles of post-Induction chemotherapy or chemoimmunotherapy, underwent tandem ASCT, had no evidence of progressive disease (PD), and met organ function criteria were eligible. Therapy, administered every 28 days, consisted of temozolomide and irinotecan on Days 1-5, dinutuximab on Days 2-5, and sargramostim on Days 6-12 during Cycles 1-5; isotretinoin on Days 8-21 during Cycles 1-6. Therapy was deemed feasible if the 95% confidence interval (CI) placed on the percentage of pts that completed 5 cycles of dinutuximab + chemotherapy without PD within 30 weeks contained 75%, and if the interim monitoring rules for feasibility and excessive toxicity were not triggered. Event-free (EFS) and overall survival (OS) were determined from time of enrollment. Results: From 11/30/20-6/30/23, 40 eligible pts enrolled and started protocol therapy. 87.5% (n=35) were ≥18 months old and 97.5% (n=39) had INRG Stage M disease, at diagnosis. 87.5% (95% CI 73.9%, 94.5%) completed 5 cycles of dinutuximab + chemotherapy without PD within 30 weeks, exceeding the feasibility benchmark of 75%. Feasibility and monitoring rules were not triggered. Five pts were removed from protocol therapy prior to Cycle 4 physician determination (n=2), pt/parent refusal of further therapy (n=2), and PD (n=1). No unacceptable toxicities or deaths on protocol therapy were reported. Toxicities of interest are summarized (Table). One-year EFS and OS were 90.0±5.0% and 97.5±2.7%, respectively (median follow-up time for pts without event=1.2 years). Conclusions: Administration of post-consolidation chemoimmunotherapy in pts who underwent tandem ASCT is tolerable and met pre-defined feasibility criteria. The impact of this approach on survival outcomes will be studied in a future COG trial. Clinical trial information: NCT04385277 . Table: see text
Desai et al. (Sat,) studied this question.