Quadruple immunotherapy with allogeneic natural killer cell infusion for recurrent neuroblastoma

Relapsed/refractory (R/R) neuroblastoma remains lethal despite multi-modality therapy. We evaluated a quadruple immunotherapy regimen combining haploidentical natural killer (NK) cell infusion, dinutuximab beta, cytokines and spironolactone, which enhances NK cytotoxicity via retinoid X receptor gamma agonism.

In this single-arm clinical trial, children with R/R neuroblastoma received chemotherapy (cyclophosphamide/topotecan), dinutuximab beta, spironolactone, low-dose interleukin 2 and granulocyte-macrophage colony-stimulating factor along with haploidentical NK cell infusion. Cycles were repeated every 4-8 weeks until complete remission or no objective response. The primary endpoint was response rate. Adverse events were graded by Common Terminology Criteria for Adverse Events version 5.0. NK cell frequency and cytotoxicity were profiled serially.

A total of 26 cycles of quadruple immunotherapy were administered (one to 10 per patient), with the NK cell dose of each cycle ranging from 12.4 to 42 × 10⁶ cells/kg recipient weight. Three complete responses, one partial response and one minor response were achieved; both patients with bone marrow involvement cleared the disease. Grade ≥3 cytopenia occurred after all cycles, accompanied by fever; median neutropenia duration was 24.2 days (range, 13-42 days). Cytokine release syndrome was mild; no neurotoxicity occurred. All treatment-related toxicities resolved to grade ≤1 before the next course. No patient discontinued therapy because of toxicity. After NK cell infusion, blood NK cell frequencies reproducibly peaked on day 21, coinciding with effective in vitro killing of IMR-32 neuroblastoma targets in the presence of anti-GD2 antibody. The 1-year progression-free survival and overall survival rates were 60% and 100%, respectively.

Quadruple immunotherapy appeared feasible and effective for recurrent neuroblastoma with tolerable adverse effects. Future investigation regarding consolidation therapy is warranted to further improve remission durability.