Glioblastoma (GBM), WHO grade IV glioma, represents the majority of adult malignant primary brain tumors, with an incidence of 2-3 per 100,000 person-years. The survival for GBM has increased in the last decade but is still low with a median survival of 15-18 months. Recurrence after initial standard therapy, radiation therapy and chemotherapy with temozolomide, few options are available. Even with further therapy, median progression free survival at 6 months after first relapse (PFS-6) is only 15%. Similarly, anaplastic astrocytoma and anaplastic oligodendroglioma, grade III gliomas, once recurrent after radiation therapy and first-line chemotherapy, have identical therapeutic options and poor outcomes with PFS-6 of 31%. Temozolomide (TMZ) has a favorable side effect profile and is available orally, however, cytotoxicity occurs. Metronomic temozolomide at low doses on a continuous schedule, have demonstrated better survival in studies. This study will determine the recommended dose and the side effects of PCI-24781/Abexinostat with metronomic temozolomide.

Glioblastoma (GBM), WHO grade IV glioma, represents the majority of adult malignant primary brain tumors, with an incidence of 2-3 per 100,000 person-years. The survival for GBM has increased in the last decade but is still low with a median survival of 15-18 months. Recurrence after initial standard therapy, radiation therapy and chemotherapy with temozolomide, few options are available. Even with further therapy, median progression free survival at 6 months after first relapse (PFS-6) is only 15%. Similarly, anaplastic astrocytoma and anaplastic oligodendroglioma, grade III gliomas, once recurrent after radiation therapy and first-line chemotherapy, have identical therapeutic options and poor outcomes with PFS-6 of 31%. Temozolomide (TMZ) has a favorable side effect profile and is available orally, however, cytotoxicity occurs. Metronomic temozolomide at low doses on a continuous schedule, have demonstrated better survival in studies.

Participants will be enrolled to one of each of four dose levels in cohorts of 3. Dose level escalation/de-escalation will follow Bayesian Optimal Interval (BOIN) design rules based on analysis of dose-limiting toxicities (DLTs) that occur within the first cycle of protocol treatment. Protocol treatment will continue until disease progression or intolerable toxicity. Dose Levels: 1 - 60 mg PCI-24781/Abexinostat two times daily (BID), 1.5 - 80 mg PCI-24781/Abexinostat BID, 2 - 100 mg PCI-24781/Abexinostat BID, and 3 - 140 mg PCI-24781/Abexinostat BID.

The primary study objective is to evaluate the toxicities and determine the recommended dose of PCI-24781/Abexinostat with metronomic temozolomide in participants with recurrent high grade glioma, [grade III or IV glioma (glioblastoma, gliosarcoma, anaplastic astrocytoma, anaplastic oligodendroglioma)]. Other objects are to evaluate changes in the acetylation of peripheral blood mononuclear cell (PBMC) histones H3 and H4 during treatment, evaluate acetylation of histones H3 and H4 using peripheral blood exosomes, evaluate progression-free and overall survival of participants with recurrent high grade glioma treated with therapy with PCI-24781/Abexinostat and metronomic temozolomide, descriptively examine quality of life (QOL) using EORTC QLQ-C30 questionnaire and QLQ-BN20 questionnaire during treatment, characterize the pharmacokinetics (PK) of PCI-24781/Abexinostat, temozolomide, and the combination of the 2 drugs, measure tumor response, and correlate molecular profiles with tumor response.

Inclusion Criteria:

• Pathologically proven diagnosis of high grade (aka grade III or IV) glioma (anaplastic astrocytoma, anaplastic oligodendroglioma, glioblastoma, gliosarcoma)
• Prior radiation therapy and standard temozolomide; additional therapies for previous progressions are eligible (prior bevacizumab and Optune are allowed)
• Three or more months from the end of chemoradiotherapy or have biopsy or imaging consistent with disease progression
• 19 years of age or older (the age of consent in Nebraska)
• Fully recovered from any toxicity of prior therapy that, in the opinion of the investigator, could impact tolerance to the study drug
• Eastern Cooperative Oncology Group (ECOG) Performance Status of 0-2
• Adequate bone marrow reserve (ANC count ≥1,500/mm3, hemoglobin > 8 g/dL, platelet count ≥100,000/mm3)
• Adequate renal function (a serum creatinine that is at or below 2.0 mg/dL)
• Adequate hepatic function (serum AST and ALT less than 1.5 times the upper limits of normal, serum alkaline phosphatase less than 2.5 times the upper limits of normal)
• Able to provide written, informed consent
• Females of child-bearing potential must have a negative pregnancy test within 7 days of initiating study (non-child bearing potential is defined as age 55 years or older and no menses for two years or any age with surgical removal of the uterus and/or both ovaries)
• Females of reproductive potential must agree to employ an effective barrier method of birth control throughout the study and up to 6 months following treatment

Exclusion Criteria:

• Any life-threatening illness, medical condition, or organ system dysfunction which, in the investigator's opinion, could compromise the subject's safety, interfere with the absorption or metabolism of oral PCI-24781/Abexinostat, or put the study outcomes at undue risk

• Significant cardiovascular disease such as uncontrolled or symptomatic arrhythmia, congestive heart failure, or myocardial infarction within 6 months of screening, or any Class 3 or 4 cardiac disease as defined by the New York Heart Association Functional Classification

• Malabsorption syndrome, disease significantly affecting gastrointestinal function, or resection of the stomach or small bowel or ulcerative colitis, symptomatic inflammatory bowel disease, or partial or complete bowel obstruction

• Immunotherapy, chemotherapy, radiotherapy, corticosteroids (at dosages equivalent to prednisone > 20 mg/day) or experimental therapy (other than PCI-24781/Abexinostat PO) within 4 weeks before first dose of study drug

• Concurrent use of enzyme-inducing antiepileptic drugs (phenytoin, phenobarbital, carbamazepine, felbamate, topiramate and oxcarbazepine)

• Any other active malignancy other than nonmelanoma skin cancer or controlled prostate cancer

• Known history of Human Immunodeficiency Virus (HIV) or active infection with Hepatitis C Virus (HCV) or Hepatitis B Virus (HBV) or any uncontrolled active systemic infection (no testing is required for eligibility)

• Creatinine > 1.5 x institutional upper limit of normal (ULN); total bilirubin > 1.5 x ULN (unless from Gilbert's disease), and aspartate aminotransferase (AST) or alanine aminotransferase (ALT) > 2.5 x ULN

• Pregnant or breast-feeding

• Baseline ECG duration of the ventricular action potential corrected for heart rate (QTc interval) prolongation based on Fridericia's formula is > 450 ms in males and > 470 ms in females

• Concomitant valproic acid use, or another histone deacetylases (HDAC) inhibitor

• Receiving treatment with following medications and unable to discontinue treatment or switch medications prior to study enrollment:

  • Amiodarone (Cordarone, Pacerone)
  • Arsenic trioxide (Trisenox)
  • Chlorpromazine (Aralen)
  • Cisapride (Propulsid)
  • Clarithromycin (Biaxin)
  • Disopyramide (Norpace)
  • Dofetilide (Tikosyn)
  • Doperidol (Inapsine)
  • Erythromycin (EryTab, Erythrocin)
  • Flecanide (Tambocor)
  • Haloperidol (Haldol)
  • Ibutilide (Corvert)
  • Methadone (Methadose, Dolophine)
  • Moxifloxacin (Avelox)
  • Pentamidine (Pentam, Nebupent)
  • Pimozide (Orap)
  • Procainamide (Procan, Pronestyl)
  • Quinidine (Cardioquin, Quinaglute)
  • Sotalol (Betapace)
  • Thioridazine (Mellaril)
  • Vandetanib (Zactima)