3.13.2 Compensation Participants will not be compensated on this study. 3.13.3 Reimbursement Reimbursement is based on site policy. At the NCI site, the NCI will cover the costs of some expenses associated with protocol participation. Some of these costs may be paid directly by the NIH and some may be reimbursed to the participant/guardian as appropriate. The amount and form of these payments are determined by the NCI Travel and Lodging Reimbursement Policy. 3.14 CRITERIA FOR REMOVAL FROM PROTOCOL THERAPY AND OFF STUDY C RITERIA Patients can be taken off the protocol therapy and/or study as a whole at any time at their own request, or they may be withdrawn at the discretion of the investigator for safety, behavioral or administrative reasons. Prior to documenting removal from study, effort must be made to have all subjects complete a safety visit approximately 30 days following the last dose of study therapy. The following evaluation will occur: KPS Toxicity Assessment Physical & Neurological Exam Vital Signs and Weight CBC with Diff, Comprehensive Chemistry Panel, T3, T4, and TSH Tumor Imaging MDASI-BT Correlative Blood Collection 3.14.1 Criteria for Removal from Protocol Therapy The reason(s) for discontinuation must be clearly documented on the appropriate eCRF and may include: Patient voluntarily withdraws from treatment (follow-up permitted) Patient demonstrates disease progression after beginning treatment Patient experiences unacceptable toxicity Treating physician determines that continuation with treatment on the study would not be in the patient’s best interest 58 Abbreviated Title: GBM Pembro HSPPC Version Date: 03/26/2024 Patient develops a second malignancy that requires treatment which would interfere with this study Patient becomes pregnant Patient completes treatment as outlined in section 3.3 Screen failure 3.14.2 Off Study Criteria The reason(s) for discontinuation must be clearly documented on the appropriate eCRF and may include: Screen failure Tumor is identified as a methylated MGMT promoter Tumor is not IDH wildtype by pathology Investigator decision to end study Patient withdraws consent (no follow-up permitted) Patient is unable to comply with protocol requirements Patient becomes lost to follow-up (LTF) Death 3.14.3 Lost to Follow-up A participant will be considered lost to follow-up if he or she fails to return for 3 scheduled visits and is unable to be contacted by the study site staff. The following actions must be taken if a participant fails to return to the clinic for a required study visit: The site will attempt to contact the participant and reschedule the missed visit within 24 hours, and reschedule within 7 days and counsel the participant on the importance of maintaining the assigned visit schedule and ascertain if the participant wishes to and/or should continue in the study.