Phase I/II Safety of Intracerebral CART45RA‑NKG2D Cell Therapy with Autologous IL‑15‑Stimulated NK Cells in Pediatric and Young Adult Patients with High‑Grade CNS Tumors

Safety of the autologous NKIL15 and CART‑NKG2D cell products administered loco‑regionally in children, adolescents, and young adults with recurrent or refractory high‑grade CNS tumours is the primary objective, defining tolerability of intracerebral cellular immunotherapy. Secondary objectives include: efficacy assessment of tumor response; evaluation of feasibility of ATMP manufacturing; monitoring of tumor cells in cerebrospinal fluid; quantification of NKIL15 and CART‑NKG2D cells in CSF; and analysis of cytokines in CSF as pharmacodynamic markers.

The trial enrolled male and female patients aged 0 to 20 years with recurrent or refractory high‑grade CNS tumours, including medulloblastoma, atypical teratoid/rhabdoid tumour, ependymoma and high‑grade gliomas of the brain or spine. Eligible participants required histological confirmation of tumor at diagnosis or relapse, measurable or evaluable disease, and an assessment by a neurosurgeon indicating suitability for loco‑regional ATMP cell infusion via an implanted catheter or ommaya reservoir. General health criteria included a Lansky score (for age < 16) or Karnofsky score (for age ≥ 16) of 50 or greater, recovery from prior anticancer therapy to ≤ grade 2 toxicity, and adequate bone‑marrow, hepatic and renal function. Additional requirements were controlled seizure disorder (if present), availability of tumor NKG2DL expression testing, and compliance with birth‑control measures for sexually active individuals. An interval of at least 12 weeks since radiation, and specified washout periods after chemotherapy, targeted agents, bevacizumab, or prior immunotherapies, were also mandated. The sponsor did not provide information on the total number of participants.

The study is a Phase I/II, multicentre, prospective, open‑label, randomized clinical trial evaluating loco‑regional administration of autologous NKIL15 cells or CART‑NKG2D cells in patients ≤20 years old with recurrent or refractory high‑grade central nervous system tumours. After an initial screening visit to confirm eligibility, obtain informed consent, assess performance status, perform baseline imaging, laboratory evaluations, and tumour NKG2DL expression, participants receive the first cell infusion (Day 0) via an Ommaya reservoir or intrathecal route as determined by neurosurgery. Subsequent scheduled visits occur on Days 7, 14, 28, and 48 for safety monitoring, including assessment of adverse events, performance status, cytokine release syndrome, and neurotoxicity; thereafter, monthly visits continue through month 12 to evaluate disease status, pharmacokinetics, and immunologic endpoints, culminating in an end‑of‑study visit at month 12. The overall participant involvement spans approximately 12 months from first infusion, with additional long‑term follow‑up permitted per protocol. Early termination may occur if a participant experiences a Grade 4 or higher treatment‑related toxicity, requires intensive care for cytokine release syndrome or ICANS, shows disease progression precluding further treatment, withdraws consent, or if manufacturing of the investigational cell product fails. The primary endpoint is the incidence and severity of adverse reactions and Grade ≥3 toxicities, while secondary endpoints include progression‑free survival, overall survival, objective response rate, duration of response, manufacturing success rate, detection of tumour‑derived cells and persistence of infused cells in cerebrospinal fluid, and cytokine quantification.

The investigational product designated as autologous peripheral blood‑derived NK cells stimulated ex‑vivo with interleukin‑15 is supplied as a cell suspension for injection. The preparation consists of unexpanded adult differentiated NK cells derived from the participant’s peripheral blood and activated with IL‑15 prior to administration. The product is administered loco‑regionally to the central nervous system as a solution for injection; the specific dose volume and frequency are defined in the protocol but are not disclosed in this summary. Infusion procedures are performed under aseptic conditions, and participants are observed for immediate post‑infusion reactions. Compliance with the dosing schedule is monitored through infusion records and site‑based verification of cell product identity and viability.

The second investigational agent, referred to as CART45RA‑NKG2D cells, comprises autologous peripheral blood‑derived CD45RA‑negative T cells transduced with a lentiviral vector encoding a chimeric antigen receptor targeting the NKG2D protein. The product is provided as a solution for injection and is delivered loco‑regionally to the central nervous system in accordance with the trial’s administration schedule. Details of the administered volume and administration frequency are specified in the study protocol. As with the NK cell product, infusion documentation, cell product release criteria, and post‑infusion monitoring are employed to ensure adherence to the dosing regimen and to capture any adverse events.

No placebo or standard‑of‑care comparator is described for this phase I/II study; the trial focuses on the safety evaluation of the two autologous cell‑based therapies when administered directly to the central nervous system. Ongoing compliance monitoring includes real‑time tracking of infusion times, volume administered, and systematic adverse event reporting throughout the observation period.

Efficacy will be evaluated using several secondary endpoints, including progression‑free survival (PFS), overall survival (OS), objective response rate (ORR), duration of response (DoR), successful manufacturing of the investigational cell products, detection of tumour‑derived cells in cerebrospinal fluid (CSF), persistence of NKIL15 and NKG2D‑CAR T cells in CSF, and quantification of cytokine levels in CSF. PFS is defined as the interval from treatment initiation to disease progression or death from any cause and will be assessed according to RAPNO and iRECIST criteria, with rates estimated at 3, 6, and 12 months. OS is defined as the time from treatment start to death from any cause and will be evaluated at the same time points. ORR represents the proportion of patients achieving complete or partial response per RAPNO and iRECIST criteria, and DoR measures the time from the first documented response to subsequent progression or death.

Assessment of disease status will be performed using imaging studies reviewed with RAPNO and iRECIST standards at baseline and at scheduled follow‑up visits corresponding to the 3‑, 6‑, and 12‑month intervals. Manufacturing success will be recorded when sufficient cell doses are produced to complete both planned treatment courses. CSF samples will be collected according to the study schedule for molecular analyses, including detection of tumour‑derived cells, evaluation of NKIL15 and NKG2D‑CAR T cell persistence, and measurement of cytokine concentrations using validated laboratory assays.