LAUSR

Simple Summary Naxitamab (Danyelza®) is a newly FDA-approved humanized anti-GD2 antibody for the treatment of relapsed/refractory in the bone/bone-marrow-only compartment high-risk neuroblastoma. In our center, we had the unique opportunity to use Naxitamab in patients achieving complete remission with standard management including autologous stem cell transplantation or not. In 2021, we reported the first cohort ever of such patients (n = 55) and showed very encouraging survival results at 3 years. Hereby, we present an updated report on the outcome of a larger cohort (n = 82) of patients followed for significantly longer (a median follow-up of 37 months). The results demonstrate reassuring survival rates (5-year event-free survival of 57.9% and overall survival of 78.6%) for high-risk neuroblastoma patients achieving end-of-induction complete remission. This study adds to increasing evidence that high-dose chemotherapy with an autologous stem cell transplant may not be required to achieve long-term survival in, at least, this subgroup of neuroblastoma patients. Abstract Naxitamab is an anti-GD2 antibody approved for the treatment of relapsed/refractory HR-NB. We report the survival, safety, and relapse pattern of a unique set of HR-NB patients consolidated with naxitamab after having achieved first CR. Eighty-two patients were treated with 5 cycles of GM-CSF for 5 days at 250 μg/m2/day (−4 to 0), followed by GM-CSF for 5 days at 500 μg/m2/day (1–5) and naxitamab at 3 mg/kg/day (1, 3, 5), on an outpatient basis. All patients but one were older than 18 months at diagnosis and had stage M; 21 (25.6%) pts had MYCN-amplified (A) NB; and 12 (14.6%) detectable MRD in the BM. Eleven (13.4%) pts had received high-dose chemotherapy and ASCT and 26 (31.7%) radiotherapy before immunotherapy. With a median follow-up of 37.4 months, 31 (37.8%) pts have relapsed. The pattern of relapse was predominantly (77.4%) an isolated organ. Five-year EFS and OS were 57.9% (71.4% for MYCN A) 95% CI = (47.2, 70.9%); and 78.6% (81% for MYCN A) 95% CI = (68.7%, 89.8%), respectively. EFS showed significant differences for patients having received ASCT (p = 0.037) and pre-immunotherapy MRD (p = 0.0011). Cox models showed only MRD as a predictor of EFS. In conclusion, consolidation with naxitamab resulted in reassuring survival rates for HR-NB patients after end-induction CR.