Study of Pembrolizumab and M032 (NSC 733972)

This Phase I (Cohort I and Cohort II) and Phase II trial is designed to confirm the safety and tolerability of Pembrolizumab when given in conjunction with M032, an Oncolytic Herpes Simplex Virus (oHSV) that expresses IL-12 and perform the Phase II portion using a Recommended Phase 2 Dose (RP2D) of M032 (provided by the Phase I) when given in conjunction with Pembrolizumab for recurrent malignant glioma (glioblastoma multiforme, anaplastic astrocytoma, or glio-sarcoma).

Phase I/Cohort I: For the Phase I portion of this trial, patients whose malignant gliomas recur after undergoing initial surgical resection, standard of care radiotherapy (60Gy) and standard of care temozolomide chemotherapy and who are candidates for, and would bene-fit from, a surgical debulking. Patients whose tumors have unmethylated MGMT promoters who have completed radiation therapy will also be eligible, regardless of whether or not they received temozolomide, since some centers are not using temozolomide in these patients. M032 will initially be administered directly into the tumor bed at the time of craniotomy and immediately after resection of the tumor. Patients will be treated with a total dose of 1 x 106 pfu of M032 initially and then subsequently with each dose of Pembrolizumab. If one toxicity occurs at a given dose level, that cohort will be increased to six patients. If two or more toxicities occur at the 1 x 106 pfu dose level, then a new cohort will be enrolled at 1 x 105 pfu, using the same approach. If two or more toxicities occur at the 1 x 105 pfu dose level, then the Data Safety and Monitoring Board (DSMB) will be consulted to determine if a stopping rule should be invoked or consideration of dose de-escalation to 1 x 104 pfu be considered. The highest safe dose will be considered the starting dose for Phase I/Cohort II. Details of initial dose administration of M032. Patients must be candidates for a resection of the enhancing portion of the recurrent tumor; they will undergo craniotomy, with additional burr holes as needed, and then stereotactic placement of up to 4 infusion catheters. Planned catheter tip locations will include: a) \> 2.5 cm from a cortical surface; b) \> 1 cm from an ependymal surface or the margin of the planned resection cavity; and c) if possible, \> 0.5 cm from a sulcus. This will minimize loss of dose into the subarachnoid or intra-ventricular space during subsequent M032 inoculations. Only after catheters have been successfully placed (with Rickham reservoirs used to cap off catheters and hold them in place for the remainder of surgery) will patients will then undergo resection of the enhancing portion of the tumor. Subsequent to the resection but prior to dural closure, M032 will be administered if no ventricular entry has occurred during the resection. M032 will be administered by by multiple free hand injections into the resected tumor bed, using approximately equal volumes at each site (6 ml total). Each inoculation will be administered \~1 cm apart and delivered into the resected tumor bed over 1 minute and at a 1 cm depth (28G, 1/2-inch needle fitted to a 1-cc tuberculin syringe), where possible. Injections will be placed with careful avoidance of penetration of the ventricular system or any significant vascular structures, and any of the already-placed catheters. Intraoperative ultrasound will be used as needed to define positions of structures or catheters to avoid. After each inoculation the needle will be left in place for up to two minutes before removal and, after removal, the entry site will be covered with hemostatic agent. Both of these measures should minimize reflux of inoculum back into the tumor cavity. Before closing the dura, a fifth catheter will be left in place and then anchored with a Rickham in the tumor resection cavity to allow later access for CSF collection. This Rickham will not be used for M032 administration. The surgical procedure will then be completed in standard fashion. If ventricular entry has occurred during surgery, no M032 will be administered intraoperatively. Instead, a post-operative CT scan will be obtained on Day 1, and the initial M032 dose will be administered as outlined below, using all catheters felt to be appropriately positioned adjacent to the tumor cavity without violating the constraints of the exclusion criteria. Pembrolizumab treatment and subsequent treatments of M032. Starting at week four, patients will undergo treatment on the same day, and every three weeks thereafter, with intra-venous infusion of 200mg of Pembrolizumab (for dosing detail, see Section 5.2.1). A total of 3 combined doses of Pembrolizumab and M032 will be given. Patients will then undergo treatment with inoculation of the calculated total dose of M032 as follows: each total dose (1 x 105 pfu for dose level one, 1 x 106 pfu for dose level two) directly into the remaining tumor bed at the time of craniotomy and immediately after resection for a particular dose level will be divided into up to four aliquots depending on the number of catheters available for inoculation. Each aliquot will be 1ml in total volume, consisting of 0.5 ml of M032 and will be infused over two minutes after puncture of each individual reservoir with a 22-24 g needle (using sterile techniques, after sterile preparation of the overlying scalp), followed by 0.5 ml of preservative free saline. Determination of the suitability of each reservoir/catheter for inoculation will be made by the PI before each dosing and will include known patency status of each catheter, location of catheter tip and degree of adherence to the placement guidelines described above; 3) concerns for associated neurotoxicity related to M032 and/or inflammation in area of a particular reservoir/catheter tip; and 4) availability of other catheters for inoculation. Catheters whose reservoir(s) are closely associated with overlying scalp infections/inflammation will not be injected. Each catheter will be gently aspirated after the Rickham has been accessed but prior to M032 inoculation; catheters from which CSF can be aspirated will not be inoculated to avoid inoculation into the CSF space. The MRI obtained immediately prior to assessment (see schedule, below) will be used to help inform the decision-making above. If there is any question regarding reservoir/catheter suitability, an additional CT or MRI may be obtained prior to inoculation at the PI's discretion. Combined Pembrolizumab and M032 treatments at each dose level will be repeated at three-week intervals for up to three cycles total, or until unacceptable toxicity or tumor progression occurs. Patients who are responding to treatment may be considered for additional dosing after the trial period has been completed. The first two patients treated will not require any waiting period between enrollments. If one of the two should develop a toxicity, the third and subsequent (up to six) patients at that level will not be enrolled until seven weeks from the initial dose of M032 and three weeks from the first combined dose of Pembrolizumab and M032 has transpired for the initial two patients and every patient thereafter, to allow adequate duration of time for development of potential dose limiting toxicities in each treated patient before treating the next patient at that level. Patients will undergo and then subsequently with each dose of Pembrolizumab; i If one toxicity occurs at a given dose level, that cohort will be increased to 6 patients. If 2 or more toxicities occur at the tested dose level, then with the approval of the DSMB, the dose will be de-escalated by one log and a new cohort enrolled with similar rules at the level. If 2 or more toxicities occur at the de-escalated dose level, then the DSMB will be consulted to determine if a stopping rule should be invoked or consideration of further dose de-escalation should be considered. The investigators anticipate as few as four patients (given two or more DLTs initially) and as many as 12 (only one DLT at each dose level). However, based on experience with M032 and Pembrolizumab, the investigators expect that this combination will not pro-duce any dose-limiting toxicities (DLTs). Phase I/Cohort II: Having established for the safety and tolerability of M032 in conjunction with Pembrolizumab in patients with recurrent Malignant Glioma (MG), the trial will immediately transition into a Phase I Cohort II study of Pembrolizumab and M032 in patients with newly diagnosed MG. Patients who are previously untreated but suspected of having a high grade glioma by MRI and are eligible for craniotomy and resection will be offered participation in this two-Cohort trial. As in Phase I Cohort I, for the Phase I/Cohort II, consented subjects will have safe gross total resection, implantation of up to four Rickham catheters in the peritumoral brain and M032 injected into the wall of the resection cavity as described above. Patients will be treated with a total dose of of M032 initially at the time of craniotomy as determined in Cohort I, above. They will then undergo treatment with standard fractionated radiation, and temozolomide as determined by treating physician. Starting at week four, patients will undergo treatment on the same day, and every three weeks thereafter, with intra-venous infusion of 200mg of Pembrolizumab (for dosing detail, see Section 5.2.1) and intratumoral M032 (via the Rickham-catheters placed at the periphery of the tumor cavity-the catheter left in the tumor cavity itself will not be used for M032 inoculation, but only to access CSF). Patients will then undergo treatment with inoculation of the calculated total dose of M032 for that dose level divided into up to four aliquots depending on the number of catheters available for inoculation. Each aliquot will be 1ml in total volume, consisting of 0.5 ml of M032 and will be infused over 2 minutes after puncture of each individual reservoir with a 22-24 g needle (using sterile techniques, after sterile preparation of the over-lying scalp). Determination of the suitability of each reservoir/catheter for inoculation will be made by the PI before each dosing and will include known patency status of each catheter, location of catheter tip and degree of adherence to the placement guidelines described above; 3) concerns for associated neurotoxicity related to M032 and/or inflammation in area of a particular reservoir/catheter tip; and 4) availability of other catheters for inoculation. Catheters whose reservoir(s) are closely associated with overlying scalp infections/inflammation will not be injected. Each catheter will be gently aspirated after the Rickham has been accessed but prior to M032 inoculation; catheters from which CSF can be aspirated will not be inoculated to avoid inoculation into the CSF space. The MRI obtained immediately prior to assessment (see schedule, below) will be used to help inform the decision-making above. If there is any question regarding reservoir/catheter suitability, an additional CT or MRI may be obtained prior to inoculation at the PI's discretion. Combined Pembrolizumab and M032 treatments at each dose level will be repeated at three-week intervals for up to three cycles total, or until unacceptable toxicity or tumor progression occurs. Patients who are responding to treatment may be considered for additional dosing after the trial period has been completed. The first two patients treated will not require any waiting period between enrollments. If one of the two should develop a toxicity, the third and subsequent (up to six) patients at that level will not be enrolled until seven weeks from the initial dose of M032 and three weeks from the first combined dose of Pembrolizumab and M032 has transpired for the initial two patients and every patient thereafter, to allow adequate duration of time for development of potential dose limiting toxicities in each treated patient before treating the next patient at that level. Patients will undergo and then subsequently with each dose of Pembrolizumab; i If one toxicity occurs at a given dose level, that cohort will be increased to 6 patients. If 2 or more toxicities occur at the tested dose level, then with the approval of the DSMB, the dose will be de-escalated by one log and a new cohort enrolled with similar rules at the level. If 2 or more toxicities occur at the deescalated dose level, then the DSMB will be consulted to determine if a stopping rule should be invoked or consideration of further dose de-escalation should be considered. The investigators anticipate as few as four patients (given two or more DLTs initially) and as many as 12 (only one DLT at each dose level). However, based on experience with M032 and Pembrolizumab, the investigators expect that this combination will not produce any dose-limiting toxicities (DLTs). Phase II: Having established for the safety and tolerability of M032 in conjunction with Pembrolizumab in patients with newly-diagnosed MG, the trial will immediately transition into a Phase II study of Pembrolizumab and M032 in patients with newly diagnosed MG. Patients who are previously untreated but suspected of having a high grade glioma by MRI and are eligible for craniotomy and resection will be offered participation in this two-Cohort trial. Unlike the Phase I, patients will be eligible to receive Pembrolizumab and M032 every 3 weeks for up to one year. The Phase II design will employ the Simon two-stage optimal study design. It will be a single-arm open-label study of M032+ pembrolizumab and the primary endpoints of Over-all Survival at 12 months and 24 months, and Progression Free Survival rate at 6 months (PFS-6). In the first stage, 6 patients will be accrued. Data will be allowed to mature, and an interim analysis per-formed at that time. During this period, additional subjects may be accrued. If there are 2 or fewer responses in the initial 6 patients, further accrual to the study may be stopped. Otherwise, 10 additional patients will be accrued for a total of 16. The null hypothesis will be rejected if 11 or more responses are observed in 16 patients. This design yields a type I error rate of 0.05 and power of 80% when the PFS-6 is 75%. To allow for 25% unevaluable subjects, a maximum of 22 subjects will be enrolled.