129P - Naxitamab efficacy in patients with refractory/relapsed high-risk neuroblastoma and bone metastases as assessed by Curie score

Background

High-risk neuroblastoma (HR-NB) commonly metastasizes to the bone, a frequent site of resistant disease. Naxitamab, a humanized GD2-binding monoclonal antibody, in combination with granulocyte-macrophage colony-stimulating factor (GM-CSF), has previously been shown to be effective in the treatment of bone metastases. Here we report the maximum change in Curie score (CS) from baseline based on Trial 201 prespecified interim analysis.

Methods

Trial 201 (NCT03363373, data cutoff 31 Dec 2021) is a Phase 2 study evaluating naxitamab in combination with GM-CSF in patients (pts) with HR-NB with an incomplete response in bone/bone marrow after induction or relapse therapy. Naxitamab was administered intravenously (3 mg/kg/day) on days 1, 3, and 5, and GM-CSF was administered subcutaneously on days -4 to 5 in 4-week cycles. CS and treatment response were evaluated by use of ¹²³I-MIBG scans per independent review in accordance with the International Neuroblastoma Response Criteria. The current analysis reports on the maximum change in CS from baseline in the overall efficacy population and in relapsed and refractory subgroups.

Results

A total of 48 pts with evaluable disease in bone and at least 1 postbaseline CS were eligible for assessment. A summary of baseline and maximum CS change for the overall and relapsed/refractory subgroups are presented in the Table. Among the 20 (42%) pts with a 100% decrease in CS, the median and mean baseline CSs were 2.5 and 4.8, respectively. Notably, 46/48 (96%) pts achieved a decreased or stable CS. Related grade ≥3 adverse events reported in ≥10% of pts included pain, hypotension, urticaria, and bronchospasm and were manageable with appropriate interventions in place. Table: 129P

Conclusions

The maximum change in CS provides a measure of best bone response and demonstrates that naxitamab has the potential to significantly reduce the disease burden in the bones of pts with HR-NB. Safety was in line with prior observations.

Clinical trial identification

NCT03363373.

Legal entity responsible for the study

Y-mAbs Therapeutics.

Funding

Y-mAbs Therapeutics.

Disclosure

J. Mora: Financial Interests, Personal, Speaker, Consultant, Advisor: Y-mAbs. D.A. Morgenstern: Financial Interests, Personal, Speaker, Consultant, Advisor: Y-mAbs, Clarity Pharmaceuticals, Oncoheroes Biosciences, Razyebio, Regeneron, AbbVie. K. Nysom: Financial Interests, Personal, Advisory Board: Y-mAbs, Bayer, EUSA. J. Faber: Financial Interests, Personal, Local PI: Y-mAbs. A. Wingerter: Financial Interests, Personal, Advisory Board: Y-mAbs, EUSA. M. Bear: Financial Interests, Personal, Advisory Board: Y-mAbs. M. During, K. Tornøe: Financial Interests, Personal, Full or part-time Employment: Y-mAbs. All other authors have declared no conflicts of interest.