Treatment With Azacitidine of Recurrent Gliomas With IDH1/2 Mutation

Scientific justification:

Gliomas are the most frequent brain tumors. Prognosis is poor. It depends on the histological grade (I to IV), and on the molecular profile, and particularly on the presence of IDH (Isocitrate dehydrogenase) mutation which is associated with a better prognosis. Mutations of IDH1R132, less frequently IDH2R172 affect 40% of gliomas, mostly grade II and grade III. IDH mutation results in the accumulation of D-2 hydroxyglutarate (D2HG) produced by the IDH1 mutant enzyme. D2HG acts as a competitive inhibitor of the alphaketoglutarate cofactor in a wide range of cellular reactions, including TET family enzymes and histone demethylases, resulting in DNA hypermethylation (CpG Island Methylator Phenotype, CIMP) and histone hypermethylation. IDH mutation is probably the earliest genetic alteration in the tumorigenesis of gliomas, and is also the most stable, as shown in a whole exome analysis of initial and recurring low grade gliomas. It is therefore an attractive target. In an attempt to reverse the CIMP status, in vitro and in vivo experiments showed a dramatic anti-tumor effect of hypomethylating drugs (5-azacytidine and 5-deoxyazacytidine) on IDH1 mutated human gliomas . These hypomethylating drugs are routinely used in myelodysplasic syndrome and are well tolerated. Despite glioma with IDH1/2 mutation have a better outcome compared to the IDH wild-type counterpart, the prognosis remains grim with no therapeutic perspective after radiotherapy, temozolomide and/or nitrosourea treatment. Another reason to administer the hypomethylating drug after failure of alkylating chemotherapy is based on the assumption that demethylation of O6-methylguanine-DNA-methyltransferase (MGMT) promoter could compromise the efficacy of future alkylating treatment. Based on preclinical data obtained in animal models and clinical data of patients with MDS, we will treat with demethylating drug (Azacitidine, Vidaza®) patients with recurrent IDH mutated gliomas (as authentificated by IDHR132H Immunochemistry or direct sequencing). Preclinical data on experimental gliomas and clinical data on MDS, has shown that efficacy is delayed by three or more cycles. This has important consequences in the selection of the population, and the follow-up of the treatment. We will exclude patients with important mass effect and intracranial hypertension, and more generally patients whose life expectancy is inferior to 9 months. Despite such treatment has never been evaluated in IDH mutated glioma patients, the biological and preclinical backgrounds are extremely strong and the drug is well tolerated and widely used in the field of haematology.

Azacitidine is believed to exert its antineoplastic effects by multiple mechanisms including cytotoxicity on abnormal haematopoietic cells in the bone marrow and hypomethylation of DNA. The cytotoxic effects of azacitidine may result from multiple mechanisms, including inhibition of DNA, RNA and protein synthesis, incorporation into RNA and DNA, and activation of DNA damage pathways. Non-proliferating cells are relatively insensitive to azacitidine. Incorporation of azacytidine into DNA results in the inactivation of DNA methyltransferases, leading to hypomethylation of DNA.

DNA hypomethylation of aberrantly methylated genes involved in normal cell cycle regulation, differentiation and death pathways may result in gene re-expression and restoration of cancer suppressing functions to cancer cells. The relative importance of DNA hypomethylation versus cytotoxicity or other activities of azacitidine to clinical outcomes has not been established.

Azacitidine is small molecule. Pharmacokinetic data suggest a good penetration in the Central Nervous System (CNS). 5-aza-dCyd, active metabolite of azacitidine, can cross the blood-Cerebro Spinal Fluid (CSF) barrier effectively, producing cytotoxic concentrations in the CSF when given by i.v. infusion in animal models .

In IDH mutated tumors, it is believed that the inactivation of tumor suppressor genes by aberrant DNA methylation of CpG islands plays an important role in the development of malignancy. DNA methylation usually occurs at the 5-position of the cytosine ring within cytosine-phosphate-guanine (CpG) dinucleotide by a transfer of the methyl group from S-adenosyl-L-methionine. Azacitidine reactivates many tumor suppressor genes that are aberrantly silenced in hypermethylated tumors, including Rb, p53, CDKN2A, and mismatch repair genes which are involved in alkylating resistance. It may also reactivate MGMT, which makes the cell more sensitive to alkylating drugs: this may be a deleterious effect. This is one more reason to reserve this treatment to patients previously treated with alkylating drugs which developed secondary resistance: one of the mechanisms of resistance is the inactivation of mismatch repair genes which occurs after alkylating treatment and is a mechanism of secondary resistance in MGMT promoter methylated gliomas. Re-expressing these genes may render the tumor more sensitive to chemotherapy.

Description and justification of the dosage, route of administration, administration schedule and treatment duration:

Vidaza® is approved by the European Commission for the treatment of adult patients who are not eligible for haematopoietic stem cell transplantation (HSCT) with: intermediate-2 and high-risk myelodysplastic syndromes (MDS) according to the International Prognostic Scoring System (IPSS),, chronic myelomonocytic leukaemia (CMML) with 10-29 % marrow blasts without myeloproliferative disorder, acute myeloid leukaemia (AML) with 20-30 % blasts and multi-lineage dysplasia, according to World Health Organization (WHO) classification, AML with >30% marrow blasts according to the WHO classification.

In these approved indications, the recommended starting dose for the first treatment cycle, for all patients regardless of baseline haematology laboratory values, is 75 mg/m2 of body surface area, injected subcutaneously, daily for 7 days, followed by a rest period of 21 days (28-day treatment cycle) every 4 weeks until progression, intolerance or end of the study. It is recommended that patients be treated for a minimum of 6 cycles. In absence of study in neuro-oncology, it was decided to use same dosage and schedule as in haematological malignancies.

Summary of the known and foreseeable benefits and risks for the study participants:

In this population, there is currently no available treatment, shown to have any efficacy. Despite there is no data on efficacy of azacitidine in this population there is a strong biological and preclinical background. Furthermore the tolerance is well known since the drug is widely used in hematology. The toxicity is mostly haematologic and renal and easily manageable. However there are two caveats:

• Since the response is delayed, we expect no effect before 3 cycles. Moreover neurological worsening must be expected and anticipated and treated if necessary by introducing or increasing steroids.
• Demethylation modifies gene expression and reactivates tumor suppressor genes; however we cannot not exclude a deleterious effect (ie reactivation of deleterious genes). This is a theoretical risk though it has not been reported in the MDS and AML treated with azacitidine.

Objectives and endpoints:

The primary objective of this study will be to evaluate the efficacy based on RANO criteria, of azacitidine in patients with recurrent IDH1/2 mutated glioma after conventional treatments. The primary assessment criterion will be Progression-Free Survival at 6 months (PFS-6) (24 weeks) estimated by the RANO criteria.

The Secondary objectives will be 1/ to evaluate the clinical efficacy: objective response rate after 6 cycles of treatment evaluated by RANO criteria and overall survival, 2/ to evaluate the safety and tolerability of azacitidine by description and graduation of adverse events according to the revised NCI Common Terminology Criteria for Adverse Events (CTCAE V4.0).

Design of the Study:

The AGIR Trial will be a phase II, non-comparative, open label, non randomised monocentric trial evaluating efficacy of a treatment by azacitidine in recurrent IDH1/2 mutant gliomas.

Statistical aspects:

A Fleming two-stage design is used to assess the efficacy of Azacitidine on the 6-months progression free survival. Minimal efficacy (p0) and expected efficacy (p1) are respectively fixed to 15% and 30%. With a type I error rate of 5%, and an 80% power, 19 patients are required for the first step, and 36 additional patients for the second step if no conclusion has been reached at intermediate analysis. In this configuration we plan to enroll 63 patients in order to have 55 patients who will receive at least 1 cycle of treatment.