NB is the most common extracranial solid tumor in children and infants. Despite recent advances in HR-NB treatment, there remains a high unmet need for those with R/R disease. Naxitamab is a humanized GD2-targeted immunotherapy with a high affinity for GD2, abundantly expressed in NB.
In Trial 201 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 wks. Granulocyte-macrophage colony-stimulating factor (GM-CSF) was administered subcutaneously daily for 10 days starting 5 days prior to naxitamab. Patients (pts) were eligible if disease was limited to bone and/or bone marrow. Pts with relapse NB were eligible following salvage therapy and with no progressive disease at trial entry. International criteria (JCO 2017;35:2580) defined responses.
22 pts were included in the primary efficacy analysis; 36 pts were included in the updated safety analyses. Mean number of prior systemic therapy lines was 1.4. Pts could receive more than one systemic therapy per line. By independent review, the overall response rate (ORR) was 68% (15/22) with 59% (13/22) complete responses (CR). In refractory pts the ORR was 71% (10/14) with 64% CR (9/14) and in relapsed pts the ORR was 63% (5/8) with 50% CR (4/8). 32/36 pts received >2 treatment cycles and naxitamab was successfully administered in an outpatient setting in 95% (495/519) infusions. The median (min; max) duration of all infusions was 0.62 hr (0.12; 1.62). 8 pts reported 9 naxitamab-related SAEs: 4 anaphylactic reaction, 2 hypotension, 1 laryngeal oedema, 1 pyrexia, 1 respiratory depression. Naxitamab-related TEAEs grade 3 or higher were reported in 30 (83%) pts; 4 (11%) pts had grade 4 and no pt had grade 5. 3 pts discontinued treatment due to gr 4 naxitamab-related TEAE: 2 anaphylactic reaction, 1 respiratory depression.
Naxitamab+GM-CSF administered in the outpatient setting can achieve major responses in R/R HR-NB, an area of high unmet need. AEs were generally manageable with timely recognition and intervention.
Clinical trial identification
Under direction and guidance from the authors, the initial version of this poster was drafted by Helle Aaes, Senior Medical Writer at Y-mAbs Therapeutics.
Legal entity responsible for the study
J Mora: Advisory/Consultancy: Y-mAbs Therapeutics. D.A. Morgenstern: Advisory/Consultancy, Speaker fee: Y-mAbs Therapeutics; Advisory/Consultancy: Boringer-Ingelheim, Bayer, Roche, Clarity Pharmaceuticals; Speaker fee: EUSA Pharma; Research grant/Funding (institution): BMS. K. Nysom: Advisory/Consultancy: Y-mAbs Therapeutics, Bayer. L. Worsaae Dalby: Full/Part-time employment: Y-mAbs Therapeutics. S. Lisby: Full/Part-time employment: Y-mAbs Therapeutics. All other authors have declared no conflicts of interest.