The purpose of this research study will be to evaluate the safety and effectiveness of two investigational drugs, All-trans retinoic acid (ATRA) and Retifanlimab (anti-PD1 monoclonal antibody), in treating recurrent IDH-mutant gliomas. Objective radiographic response (CR + PR + MR) using Response Assessment in Neuro-Oncology (RANO) criteria by measurable disease (assessed separately in Phase 2 Arms A and B). Rates and severity of adverse events per CTCAE (version 5.0) in the Safety Run-In and Phase 2 cohorts (Arms A and B). Rates and severity of adverse events per CTCAE (version 5.0) in the Surgical cohort (Arms C and D). Progression-free survival (PFS) in the Phase 2 Portion (Arms A and B): the time from date of enrollment until the earliest date of disease progression (as determined by modified RANO criteria) or death due to any cause, whichever occurs first. Progression-free survival (PFS) in the Surgical Portion (Arms C and D): the time from date of enrollment until the earliest date of disease progression (as determined by modified RANO criteria) or death due to any cause, whichever occurs first. Overall survival (OS) in the Phase 2 Portion (Arms A and B): the time from date of enrollment until death from any cause. Overall survival (OS) in the Surgical Portion (Arms C and D): the time from date of enrollment until death from any cause. Duration of response (CR or PR or MR) in Arms A and B: the time from date of initial scan of a response to date of the initial scan deemed tumor progression (as determined by modified RANO criteria).

You may be eligible for this study if you meet the following criteria:

• Conditions: Medical Research
• Age: 99 years or below
• Gender: All