Children and young adults (≥1 year and ≤ 39 years) with recurrent or progressive malignant brain tumors will be eligible. The first 3 participants enrolled will be ≥ 8 years and ≤ 39 years.

Over the past decade, immunotherapy has emerged as a highly effective treatment modality against malignancies. However, with the exception of cancers arising in patients with mismatch repair deficiencies, pediatric cancers in general and brain tumors specifically have extremely low mutational burden, a central requirement for responses to checkpoint inhibitors. Likewise, surface antigens that allow safe and effective targeting by chimeric antigen receptor (CAR) T cells have yet to show efficacy outside of hematologic cancers. In contrast, NK cells are critical immune effector cells which have the ability to recognize cancer in a non-antigen-dependent manner and have been harnessed as a promising therapeutic strategy against advanced cancers. We have established Good Manufacturing Practice (GMP) infrastructure at Nationwide Children’s Hospital (NCH) to efficiently generate clinical-grade patient-derived NK cells and have extensively tested their preclinical activity against several malignancies including brain tumors. We demonstrated that the membrane-bound IL-21 (mbIL21) -expressing feeder cells promote sustained proliferation of mature NK cells without senescence by increasing the telomere length in the expanded cells.  The method enables large-scale expansion of NK cells from a small volume of peripheral blood, sufficient to deliver multiple infusions of NK cells at high cell doses. Additionally, a primary mechanism of immune escape by solid tumors is the secretion of TGFβ, which we were able to bypass by our recently modifying the expansion method to enhance NK cell function and overcome TGFβ-induced suppression [referred to as TGFβ “imprinting” (TGFβi)] by chronically stimulating the NK cells with TGFβ during the expansion process. The use of autologous cells is also logistically challenging and requires costly manufacturing for each patient product. Hence, through our collaboration with Be The Match Biotherapies (BTMB), we identify individuals with optimal NK cell characteristics who subsequently undergo donor screening, collection, and expansion of the NK cell to generate the UD NK cell bank. This study will be the first clinical trial to utilize this “off-the shelf” NK cell product in pediatric brain tumors. We hypothesize that intra-tumoral infusions of ex vivo expanded UD TGFβi NK cells will be safe and feasible in participants with recurrent or progressive malignant brain tumors, and may provide therapeutic benefit. The potential advantages of direct NK cell infusion into the tumor include bypassing the blood-brain barrier and maximally concentrating NK cells inside the tumor. Participants will receive 3 cycles (consisting of one NK cell infusion per week for three weeks, followed by a rest week) over a total of 12 weeks. We will also perform several correlative studies, including Next Generation Sequencing on all the recurrent tumors in order to determine their mutational landscape, and high-parameter immunophenotyping to determine the persistence and function of the adoptively-transferred expanded NK cells. Additionally, we will utilize the Nanostring platform to determine the tumor’s immune profiles and to characterize the changes in T cell receptor (TCR) repertoire that result from NK cell infusions.

1. To determine the safety and tolerability of natural killer (NK) cells that have been propagated ex vivo with genetically-modified feeder cells and administered intra-tumoral via an Ommaya reservoir in participants with recurrent or progressive malignant brain tumors.
2. To determine the recommended phase 2 dose (RP2D) for NK cells that have been propagated ex vivo with genetically-modified feeder cells and administered intra-tumoral via an Ommaya reservoir in participants with recurrent or progressive malignant brain tumor.

Inclusion Criteria

• Participants must have a histologically-confirmed recurrent or progressive malignant brain tumor, including, but not limited to, infant-type hemispheric glioma, gliosarcoma, intracranial sarcoma, and WHO Grade II ependymoma.
• Participants should be candidates for resection of the recurrent tumor and be deemed candidates for placement of an Ommaya reservoir placed intra-cavitary/intra-tumoral; measurable residual tumor after surgery is not required for study entry. Pre-operative imaging needs to estimate that the resection cavity will be at least 2 cm x 2 cm in two dimensions for participants to be eligible.
• Given the lack of a standard of care treatment for children with recurrent or progressive malignant brain tumors, participants must have completed first-line treatment with radiation and/or chemotherapy prior to participating in this trial if applicable.
• All participants must be ≥ 1 year of age and ≤ 39 years of age at the time of entry into the study. The first 3 participants must be ≥ 8 years of age and ≤ 39 years of age at the time of entry into the study.
• Performance Score: Karnofsky  ≥ 50 for participants > 16 years of age and Lansky ≥ 50 for participants > 16 years of age (See Appendix A). Participants who are unable to walk because of paralysis, but who are up in a wheelchair, will be considered ambulatory for the purpose of assessing the performance score.
• Must have recovered from the acute toxic effects of prior therapy (i.e., NCI-CTCAE version 5, grade 1 or less)
  • An interval of at least 12 weeks must have elapsed since the completion of radiation therapy
  • Chemotherapy/biologic therapy: All cytotoxic chemotherapy/biologic therapy must be discontinued ≥ 7 days prior to enrollment (except 3 weeks for temozolomide and 6 weeks from last dose of nitrosoureas)
  • Immunotherapy: The last dose of anti-tumor antibody therapy must be at least 3 half-lives or 30 days, whichever is shorter, from the time of enrollment.
  • For targeted agents only, the patient should have recovered from any toxicity of the agent and have a minimum of 2 weeks since the last dose
  • For participants who have received prior bevacizumab, at least 4 weeks is required.

Organ Function Requirements

Adequate Bone Marrow Function Defined as:

• Peripheral absolute neutrophil count (ANC) >750/mm3
• Platelet count >75,000/mm3 (transfusion independent, defined as not receiving platelet transfusions for at least 7 days prior to registration).

Adequate Renal Function Defined as:

• A serum creatinine < 1.5 x upper limit normal (ULN) based on age/gender.

Adequate Liver Function Defined as:

• Total bilirubin <5 x upper limit of normal (ULN) for age; in presence of Gilbert’s syndrome, total bilirubin < 3 x ULN or direct bilirubin < 1.5 x ULN
• ALT < 3 x ULN
• AST < 3 x ULN

Adequate Neurologic Function Defined as:

• Participants with a seizure disorder may be enrolled if seizures are well-controlled. Participants on non-enzyme-inducing anticonvulsants may be excluded pending interaction(s) with the study drug.
• Signs and symptoms of neurologic deficit must be stable for > 1 week prior to registration.
• The effects of TGFβi NK cells on the developing human fetus are unknown. For this reason and because TGFβi NK cells as well as other therapeutic agents used in this trial are known to be teratogenic, women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry, for the duration of study participation and 6 months after completion of TGFβi NK cells administration. Should a woman become pregnant or suspect she is pregnant while she or her partner is participating in this study, she should inform her treating physician immediately.
• Participants must enroll in PNOC COMP if PNOC COMP is open to accrual at the enrolling institution.
• A Legal parent/guardian or patient must be able to understand and willing to sign a written informed consent and assent document, as appropriate.
• Corticosteroids: Participants who are receiving dexamethasone must be on a stable or decreasing dose for at least 1 week prior to registration. The patient’s steroid dose should be no more than a steroid-equivalent of dexamethasone 0.1 mg/kg/day (or maximum 4mg/day; whichever is the lower dose) at the time of enrollment.

Exclusion Criteria

• Tumor involvement that would require ventricular or brainstem injection or access through a ventricle or significant risk of ventricular penetration in order to deliver the TGFβi NK cells.
• Participants undergoing needle or open biopsy.
• Participants who are receiving any other investigational agents.
• Women of childbearing potential must not be pregnant or breast-feeding.
• Evidence of active uncontrolled infection or unstable or severe intercurrent medical conditions.
• Any medical condition that precludes surgery.
• Prothrombin time/international normalized ratio (PT/INR) or partial thromboplastin time (PTT) > 1.5 x ULN.
• Participants with a known disorder that affects their immune system, such as human immunodeficiency virus (HIV), or an auto- immune disorder requiring systemic cytotoxic or immunosuppressive therapy are not eligible.
• Evidence of bleeding diathesis or use of anticoagulant medication or any medication which may increase the risk of bleeding. If the medication can be discontinued >1 week prior to NK cell infusion, then the subject may be eligible following consultation with the Study Chairs.
• Participants with significant systemic or major illnesses including but not limited to: congestive heart failure, ischemic heart disease, kidney disease or renal failure, organ transplantation, or significant psychiatric disorder.
• History or current diagnosis of any medical or psychological condition that in the Investigator’s opinion, might interfere with the participants ability to participate or inability to obtain informed consent because of psychiatric or complicating medical problems.

Important note: The eligibility criteria listed above are interpreted literally and cannot be waived.

Funding is provided by CureSearch, Rally Foundation, Tommy Strong Foundation.