Pilot Study of Pembrolizumab Combined With Pemetrexed or Abemaciclib for the Treatment of Patients With High Grade Glioma

This is a prospective, open-label, multi-arm exploratory study of pembrolizumab in combination with pemetrexed or abemaciclib for the treatment of adult patients with newly diagnosed high grade glioma. Patients having a clinically planned surgical procedure (biopsy or cytoreduction) for a suspected diagnosis of high grade glioma will be approached for participation in this study. Tumor tissue obtained from surgery will be used for histological diagnosis and clinical molecular profiling, and excess tumor tissue may be collected for potential correlative studies. A small sample of blood and cerebrospinal fluid (CSF) for research will also be collected.

Once a diagnosis of high grade glioma is confirmed, the patient will be allocated to either Treatment Arm 1 (pembrolizumab + pemetrexed), or Treatment Arm 2 (pembrolizumab + abemaciclib). Treatment will be started approximately 7-42 days following surgery once the patient has recovered from surgery. Routine clinical evaluations will be performed prior to treatment initiation and throughout treatment as clinically indicated. Radiographic brain imaging will be performed approximately 21-42 after treatment initiation and then routinely for medical management. Tumor response will be assessed according to immunotherapy Response Assessment in Neuro-Oncology (iRANO) Working Group criteria.

Treatment may continue until the patient experiences unacceptable toxicity or clear disease progression. The determination of whether to stop treatment due to disease progression will be based on the investigator's evaluation of the patient's clinical and radiographic condition, taking into consideration the interpretation of localized inflammatory responses that can mimic radiographic features of tumor progress. Patients discontinuing treatment will be directed by their treating physician to either receive a different treatment regimen (e.g., standard radiation therapy with or without chemotherapy) or undergo a clinically-indicated cytoreductive surgery. If another treatment is started, clinical evaluations and response assessments will continue as clinically-indicated and blood and CSF will be collected after the first month, then every three months.