Abstract CT033: Phase I study of intraventricular infusions of autologous exvivo 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, remain dismal with no defined effective therapy. Current treatment strategies have significant toxicities and 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 central nervous system (CNS) near the tumor area, bypassing the blood brain barrier and alleviating toxicity as seen with systemic chemotherapy. We have shown the efficacy of activated and propagated NK cells to lyse and kill the MPFT in vitro and tumor explants in mice models. Also, in a first-time human in vivo pilot study, we demonstrated the feasibility of infusions of biologic agents into the fourth ventricle. Infusing biologic agents through catheters placed in 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 with intent to avoid the significant side-effects of systemic therapy. This novel trial will hopefully be able to provide therapeutic efficacy and a significant increase in the survival of these children. The current format of this trial incorporates changes including different dose, schedule, routes of intraventricular infusions of NK cells from the previously presented version of the trial, and thus submitted. Correlative studies: Cerebrospinal fluid (CSF) drawn 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 and correlating with tumor response. Methods: This trial (NCT02271711-recruiting) will proceed with infusions of NK cells directly 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 will be eligible. Three to six evaluable patients may be entered at a dose level in this study for determination of maximum tolerated dose (MTD). A minimum of nine patients and a maximum of twenty-four patients will be enrolled. After autologous expanded NK cell product have been manufactured as per good manufacturing practice (GMP) guidelines and released, patients will receive three cycles of NK cell infusions over 12 weeks. Each cycle consists of one infusion per week for three weeks followed by a rest week (week 4). Dosing is based on recipient body surface area (BSA), and three dose levels will be evaluated. Currently, the trial is in the second cohort, with no dose limiting toxicity (DLT) noted with the previous dose level. 35% of the minimal accrual has been met. Also as a secondary aim, we will evaluate the antitumor activity of the NK cell infusions within the confines of a phase I study Citation Format: Soumen Khatua, Vidya Gopalakrishnan, Laurence Cooper, Dean Lee, David I. Sandberg, Michael Rytting, Jason J. Johnson, Leena Ketonen, Diane Liu, Judy Moyes, Wafik Zaky. Phase I study of intraventricular infusions of autologous exvivo 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 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT033. doi:10.1158/1538-7445.AM2017-CT033