Abstract CT216: Phase I study of intraventricular infusions of autologous ex vivo expanded NK cells in children with recurrent/refractory malignant posterior fossa tumors of the central nervous system

Scientific background/rationale: The prognosis of recurrent/refractory medulloblastoma (MB), ependymoma (EP) and atypical teratoid/rhabdoid neoplasms (AT/RT) which constitutes the majority of malignant posterior fossa tumors (MPFT) in children, remains dismal with no defined effective therapy. Current treatment strategies have significant toxicities, thus profiling newer trials with clinical efficacy and minimal side-effects are imperative. Advantages of direct infusion of Natural Killer (NK) cells into the ventricles could enhance therapeutic efficacy by maximally concentrating them in the brain in close proximity to the tumor area, bypassing the blood brain barrier and alleviating toxicity often seen with systemic chemotherapy. We have shown efficacy of activated and propagated NK cells to lyse and kill the MPFT in vitro and tumor explants in mice models. We demonstrated in a pilot study for the first time in humans, the feasibility of infusions of biologic agents into the fourth ventricle. Infusing biologic agents into the lateral ventricles are well established in neurooncology. The current ongoing study is the first-in-human, loco-regional infusion of NK cells directly into the brain evaluating safety and efficacy in the context of a phase I trial with an intent to avoid the significant side-effects of systemic therapy. This novel trial, will hopefully be able to provide therapeutic efficacy and a meaningful increase in the survival of these children. Correlative studies: Cerebrospinal fluid (CSF) withdrawn during infusions of NK cells will be evaluated for the immunophenotype, function, persistence of NK cells and influx or presence of any other immune cells. Methods: NK cells are directly infused into the lateral or fourth ventricles, after placement of a catheter at that location. Recurrent or refractory MB, AT/RT and EP involving the brain and/or spine at original diagnosis or relapse with histological verification are eligible. Three to six evaluable patients, are entered at a dose level in this study for determination of maximum tolerated dose (MTD). A minimum of 9 patients and a maximum of 24 patients are planned to be enrolled. After autologous expanded NK cell product have been manufactured as per good manufacturing guidelines (GMP) and released, patients receive 3 cycles of NK cell infusions over 12 weeks. Each cycle consists of 1 infusion per week for 3 weeks followed by a rest week (week 4). Dosing is based on recipient body surface area (BSA) and 3 dose levels will be evaluated. Currently the trial is at the final cohort (third dose level), with no dose limiting toxicity (DLT) noted with the previous dose levels. 80% of the initial minimal accrual have been met. Also as a secondary aim we will evaluate the anti-tumor activity of the NK cell infusions within the confines of a phase I study. Trial (NCT02271711-recruiting) Citation Format: Soumen Khatua, Dean Lee, Laurence Cooper, Judy Moyes, David Sandberg, Zsila Sadighi, Heather Meador, Leena Ketonen, Michael E. Rytting, Jason M. Johnson, Dristhi Raagonanan, Diane D. Liu, Vidya Gopalakrishnan, Wafik Zaky. Phase I study of intraventricular infusions of autologous ex vivo expanded NK cells in children with recurrent/refractory malignant posterior fossa tumors of the central nervous system [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT216.