HER2-specific Chimeric Antigen Receptor (CAR) T Cells for Children With Ependymoma

PBTC-059 is a multicenter, Phase I and Surgical study of the treatment HER2-specific CAR T cells for patients with refractory or recurrent ependymoma. Phase I The primary objectives of the Phase I study are to determine the safety of intravenous injection of HER2-specific CAR T cells after lymphodepleting chemotherapy, and to evaluate the multicenter feasibility of administering up to three infusions of HER2-CAR T cells after lymphodepletion. Patients will receive one infusion of HER2psecific CAR T cells after lymphodepleting chemotherapy. Following recovery from their first treatment (no earlier than 8 weeks and no later than 12 weeks), patients will resume treatment with HER2-specific CAR T cells for up to 2 infusions after lymphodepleting chemotherapy if they meet laboratory parameters. The length of time on study for patients enrolled on the Phase I study is anticipated to be 9 months on treatment. Patients will then be followed for 15 years after treatment. Surgical Study The objective of the Surgical study is to evaluate the post-treatment tumor tissue for presence of HER2-specific CAR T cells administered intravenously in children undergoing surgical resection. The surgical study will be initiated following completion of the safety evaluation period of 6 patients treated in the Phase I study. Once the surgical study is open for enrollment, all patients who have clinical indication for surgery, except those needing urgent surgery, will be eligible for enrollment to the surgical study. Patients will receive one infusion of HER2-specific CAR T cells after lymphodepleting chemotherapy 4-6 weeks before surgical resection of their tumor, at which time samples will be taken for analysis. Following recovery from surgery (no earlier than 8 weeks and no later than 15 weeks), patients will resume treatment with HER2-specific CAR T cells for up to 2 infusions if they meet laboratory parameters. The first patient in the surgical study will complete a 6-week safety evaluation period prior to enrollment of the subsequent patient. The length of time on study for patients enrolled on the Surgical study is anticipated to be 10 months on treatment. Patients will then be followed for 15 years after treatment. Dosing All patients on Phase I and Surgical study will receive HER2 CAR T cells at a patient-specific dose level 1 (8x10\^7 CAR-positive T cells/m\^2) for infusion. The cell dose will be based on the patient weight and height obtained by the treating institution at the time of procurement. For patients whose BMI is greater than 95th percentile for given age and sex, the Body surface area (BSA) will be calculated using the ideal body weight. In the event that dose level 1 is found to have excessive toxicity, three additional doses of CAR T cells at dose level -1 (5x10\^7 CAR-positive T cells/m\^2) will be made to be used in the event that dose de-escalation occurs before a patient is enrolled for treatment.