74P Pivotal trial 201 data on outpatient administration of naxitamab (Hu3F8), a humanized GD2 targeted immunotherapy for the treatment of refractory/relapsed (R/R) high-risk (HR) neuroblastoma (NB)

For patients with R/R HR NB, the prognosis is poor and there is no standard of care. Among possible treatments for this population is immunotherapy targeting GD2, a disialoganglioside overexpressed in most NB cells. The currently available anti-GD2 chimeric antibody dinutuximab requires inpatient treatment with an infusion of 10-20 hours for 4 consecutive days. Naxitamab, a humanized GD2 receptor antibody with high affinity, is administered over at least 30 minutes in the outpatient setting. Here we describe the outpatient experience from Trial 201 in patients with bone and/or bone marrow (BM) involvement who achieved stable disease, minimal disease, or partial response following initial or subsequent therapy for R/R HR NB. In this phase II trial naxitamab was administered IV in the outpatient setting. Dosing was 9 mg/kg/cycle (∼270 mg/m2/cycle) divided into 3 doses (days 1, 3, 5) with cycles repeated every 4 weeks. Granulocyte-macrophage colony-stimulating factor (GM-CSF) was administered subcutaneously daily for 10 days starting 5 days prior to naxitamab. Patients with relapsed NB were eligible following salvage therapy and with no progressive disease at trial entry. International criteria (JCO 2017;35:2580) defined responses. Outpatient administration for the 36 enrolled patients was achieved for 495/519 (95%) of infusions with similar rates across cycles and infusions. 98% (507/519) of the administered total doses (mg) were as planned. The median (min; max) duration of all infusions was 0.62 hour (0.12; 1.62). Overall, the median duration of the 1st infusion was longer than the 2nd and 3rd (0.74 hour vs 0.60 hour). Patients received the pre-planned dose of naxitamab as an outpatient with all being infused in <2 hrs. The short duration of infusions, plus previously demonstrated ability to achieve major responses in R/R HR-NB with manageable adverse reactions, supports the use of naxitamab as an alternative treatment option for R/R HR NB patients.