Sulfasalazine and Stereotactic Radiosurgery for Recurrent Glioblastoma

Inclusion Criteria: * Histologically verified glioblastoma multiforme with recurrence (first or second relapse, all subtypes) based on the Response Assessment in Neuro-Oncology criteria. * Prior standard therapy for newly diagnosed glioblastoma consisting of surgery, standard fractionated radiotherapy to 60 Gy concomitant with Temozolomide * Has been informed of other treatment options * Must be eligible to gamma knife treatment * Tumor size ≤ 3 cm in diameter (≤ 15 cm3 ) on MRI dated no more than 30 days before SRS treatment * Must be at least 18 years of age * Must be ambulatory with a Karnofsky performance status of ≥ 70 * Life expectancy \> 12 weeks * Laboratory parameters for vital functions should be in the normal reference range. Laboratory abnormalities that are not clinically significant are generally permitted, except for the following laboratory parameters, which must be within the ranges specified: Hematology: White blood cell count: ≥ 3.0 x 109/l, Platelet count:: ≥ 100 x 109/l, Hemoglobin: ≥ 100 g/l, Total bilirubin level: \<1.5 times the upper limit of normal (ULN) (except in patients with Gilbert's Syndrome who must have a total bilirubin less than 51,3 µmol/L), alanine aminotransferase \< 3 times the ULN, Creatinine \< 1.5 times the ULN, Normal prothrombin time / international normalized ratio (PT INR) \< 1.4, Absolute neutrophil count: ≥ 1 x109/L without the support of filgrastim. * More than four weeks must have elapsed since any prior systemic therapy at the time the patient receives the preparative regimen, and patients' toxicities must have recovered to a grade 1 or less. Patients may have undergone minor surgical procedures within the past 3 weeks, as long as all toxicities have recovered to grade 1 or less or as specified in the eligibility criteria. * Signed informed consent and expected cooperation of the patients for the treatment and follow up must be obtained and documented according to national/local regulations Exclusion Criteria: * Allergy to sulfa drugs * Adverse reactions to salicylates * Known hypersensitivity to sulfasalazine, its metabolites or any of the excipients (Povidone; Maize starch; magnesium stearate; colloidal silicon dioxide) * Eligible to alternative standard treatments with temozolomide * Treatment with sulfasalazine after glioblastoma diagnosis * Participation in pharmacokinetic trial within 4 weeks * Participation in immunotherapy trial within 4 weeks * History of psychological symptoms affecting ability to consent to and/or fulfill the protocol * Other malignant diseases and multiple sclerosis * Pregnant or breast feeding patients. * Porphyria * Kidney of liver deficiencies * Glucose-6-phosphate dehydrogenase deficiency * Severe allergy or bronchial asthma * History of erythema multiforme * Significant heart failure or renal failure * Intestinal or urinary obstruction * Any reason why, in the opinion of the investigator, the patient should not participate (e.g. not able to comply with study procedures).