A Clinical Study to Improve Brain Function and Quality of Life of Patients With Newly Diagnosed Brain Tumors (Gliomas).

Inclusion Criteria: 1. Histologically confirmed, newly diagnosed CNS WHO grade 2 or 3 glioma. 2. Tumor carries an isocitrate dehydrogenase (IDH) mutation (determined by immunohistochemistry (IHC) and/or deoxyribonucleic acid (DNA) sequencing). 3. Tumor is co-deleted for 1p/19q (determined by copy number variations, fluorescence in situ hybridization (FISH), multiplex ligation-dependent probe amplification (MLPA) or other appropriate methods). 4. Biopsy (with sufficient tissue for molecular pathology) or resection. 5. Age: ≥18 years. 6. Karnofsky Performance status (KPI) ≥60%. 7. Life expectancy \>6 months. 8. Availability of formalin-fixed paraffin-embedded (FFPE) or fresh-frozen tissue and ethylenediamine tetraacetic acid (EDTA) blood for biomarker research. 9. Standard magnetic resonance imaging (MRI) ≤ 72 h post-surgery according to the present national and international guidelines. 10. Craniotomy or intracranial biopsy site must be adequately healed. 11. ≥ 2 weeks and ≤ 3 months from surgery without any interim radio- or chemotherapy or experimental intervention. 12. Willing and able to comply with regular neurocognitive and health-related quality of life tests/questionnaires. 13. Indication for postsurgical cytostatic/-toxic therapy. 14. Written Informed consent. 15. Female patients with reproductive potential have a negative pregnancy test (serum or urine) day -6 until day 0 of screening (and 3 days prior to first IMP-intake or RT). Female patients are surgically sterile or agree to use adequate contraception during the period of therapy and 7 months after the end of study treatment, or women have been postmenopausal for at least 2 years. 16. Male patients are willing to use contraception Exclusion Criteria: 1. Participation in other ongoing interventional clinical trials. 2. Inability to undergo MRI. 3. Abnormal (≥ Grade 2 CTCAE v5.0 laboratory values for hematology (Hb, WBC, neutrophils, or platelets), liver (serum bilirubin, ALT, or AST) or renal function (serum creatinine). 4. Clinically active tuberculosis; known HIV infection or active Hepatitis B (HBV) or Hepatitis C (HCV) infection, or active infections requiring oral or intravenous antibiotics or that can cause a severe disease and pose a severe danger to lab personnel working on patients' blood or tissue (e.g. rabies). 5. Any prior anti-cancer therapy or co-administration of anti-cancer therapies other than those administered/allowed in this study. History of low-grade glioma that did not require prior treatment with chemotherapy or radiotherapy is not an exclusion criterion. 6. Immunosuppression, not related to prior treatment for malignancy. 7. History of other malignancies (except for adequately treated basal or squamous cell carcinoma or carcinoma in situ) within the last 5 years unless the patient has been disease-free for 5 years. 8. Any clinically significant concomitant disease (including hereditary fructose intolerance) or condition that could interfere with, or for which the treatment might interfere with, the conduct of the study or the absorption of oral medications or that would, in the opinion of the Principal Investigator, pose an unacceptable risk to the patient in this study. 9. Any psychological, familial, sociological, or geographical condition potentially hampering compliance with the study protocol requirements and/or follow-up procedures; those conditions should be discussed with the patient before trial entry. 10. Pregnancy or breastfeeding. 11. History of hypersensitivity to the investigational medicinal product or to any drug with similar chemical structure or to any excipient present in the pharmaceutical form of the investigational medicinal product. (E.g.: In the discretion of the investigator patients are allowed to take part in the study even if they suffer from celiac disease: Cecenu contains very small amounts of gluten (from wheat starch). It is considered gluten-free and is tolerated by patients suffering from celiac disease. One capsule contains no more than 4 micrograms of Gluten.) 12. QTc time prolongation \>500 ms. 13. Patients under restricted medication for procarbazine, lomustine, vincristine and temozolomide. 14. Liver disease characterized by: 1. ALT or AST (≥ Grade 2 CTCAE v5.0) confirmed on two consecutive measurements OR 2. Impaired excretory function (e.g., hyperbilirubinemia) or synthetic function or other conditions of decompensated liver disease such as coagulopathy, hepatic encephalopathy, hypoalbuminemia, ascites, and bleeding from esophageal varices (≥ Grade 2 CTCAE v5.0) OR 3. Acute viral or active autoimmune, alcoholic, or other types of acute hepatitis. 15. Known uncorrected coagulopathy, platelet disorder, or history of non-drug induced thrombocytopenia. 16. History of autoimmune disease, including but not limited to myasthenia gravis, myositis, autoimmune hepatitis, systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease, vascular thrombosis associated with antiphospholipid syndrome, Wegener's granulomatosis, Sjögren's syndrome, Guillain-Barré syndrome, multiple sclerosis, vasculitis, or glomerulonephritis; autoimmune-related hypothyroidism (patients on a stable dose of thyroid replacement hormone are eligible for this study) and type I diabetes mellitus (patients on a stable dose of insulin regimen are eligible for this study). 17. Vaccination with life vaccines during treatment and 4 weeks before start of treatment. 18. Existing neuromuscular diseases, especially neural muscular atrophy with segmental demyelination (demyelinising form of Charcot-Marie-Tooth syndrome). 19. Chronic constipation and subileus. 20. Combination treatment with mitomycin (risk of a pronounced bronchospasm and acute shortness of breath). 21. Hypersensitivity to dacarbazine (DTIC). 22. Patients with hereditary galactose intolerance, complete lactase deficiency or glucose-galactose malabsorption (Temodal contains Lactose). 23. Patients with clinical wh