The safety and feasibility of multiple intrathecal injections of allogenic NK cells in pediatrics with refractory/recurrent brain tumors.

Background: Pediatric glioma is a rare condition that can lead to significant mortality and morbidity due to its high recurrence rate. This study is a phase I nonrandomized clinical trial that was conducted to assess the safety, feasibility, and potential efficacy of the intrathecal (IT) injection of multiple doses of allogenic NK cells in pediatric patients with refractory/recurrent gliomas.

Methods: Allogeneic NK cells were isolated from random healthy unrelated donors via positive selection of CD56 + cells. Nine patients were selected according to the inclusion criteria and received weekly doses of up to 10 doses of 5 × 10⁷ NK cells/injection. Adverse events grading was done based on Common Terminology Criteria for Adverse Events (CTCAE) Check lists. The size of the tumor, degree of spinal spreading and duration of relapse during 18 month followup were considered components of efficacy. Additionally, six patients who received conventional treatment were selected retrospectively.

Results: Multiple intrathecal injections of allogeneic NK cells in pediatric gliomas were safe, without any serious adverse events (SAEs). The most prevalent AEs were headache [29% (17% grade 1 and 13% grade 2)], fever and chills [21% (17% grade 1 and 4% grade 2)], vomiting [13% grade 2], and back pain [12% (4% grade 1 and 8% grade 2)]. 18 months of follow-up, among the five patients in the intervention group who were still alive (August 7, 2024), three exhibited stable disease (SD), one had progressive disease (PD), and one experienced a partial response (PR) with a reduction in tumor size. Among the four deceased patients, two died due to tumor progression, and two died due to infections. In the retrospective control group, five out of six patients developed PD and leptomeningeal spread (LMS), four of whom died, and one patient showed radiological evidence of a complete response (CR). Cerebrospinal fluid (CSF) analysis revealed increases in the percentages of NK and T cells and significant reductions in the levels of IFN-γ and TNF-α.

Conclusions: Multiple intrathecal injections of allogeneic NK cells are safe and feasible in pediatric patients with refractory/recurrent gliomas. Although we reported a reduction in recurrence episodes and an increase in overall survival, further studies with extended follow-up periods and appropriate control groups are necessary to assess the efficacy of NK cell therapy in these patients.

Trial registration: The trial was registered on the Iranian Registry of Clinical Trials (IRCT20170122032121N6), Date 2021-11-19.