Ketogenic Diet as Adjunctive Treatment in Refractory/End-stage Glioblastoma Multiforme: a Pilot Study (KGDinGBM)

Malignant gliomas are the most common type of brain tumor in adults. They are the second leading cause of cancer mortality in people under the age of 35 and the fourth leading cause in those under the age of 54. Standard therapy for glioblastoma multiforme (GBM) includes surgery followed by radiation and chemotherapy. Despite optimal treatment the prognosis remains poor. Patients with GBM have a median survival of approximately 10-15 months. Essentially all patients suffer recurrent disease, usually within 8 months of diagnosis. For patients with malignant glioma whose tumors recur, the median time to tumor progression is 9-13 weeks with the current standard of treatment for recurrent glioblastoma, bevacizumab (AVASTIN®). There is an urgent need for more effective therapies.

GBM cancer cells depend on glucose for energy supply and survival. When glucose levels are reduced, normal brain cells metabolize ketone bodies for energy. Brain tumor cells cannot do so. This makes the tumor cells vulnerable to death using therapies that target glucose metabolism. In brain cancer patients, high blood glucose levels are associated with reduced survival. In mice, reduction in circulating glucose levels through ketogenic diet (KD) reduces tumor growth

Ketogenic diet (KD) reduces blood glucose levels while elevating levels of ketone bodies, and may thus be beneficial in the treatment of GBM as a non-toxic metabolic therapy. KD is a high fat, low carbohydrate diet used for treatment of refractory seizures. There have been two case reports of KD use in patients with GBM showing slowing of tumor progression.

Ketogenic diet (KD) is a high fat, low protein, low carbohydrate diet that is an effective treatment of refractory epilepsy in children. The diet consists of long chain saturated triglycerides with a 3:1 or 4:1 [fat] : [protein + carbohydrate] ratio by weight, with 87-90% of calories derived from fat. The investigators have recently evaluated KD with caloric restriction of 1600 kcal /day in adults with refractory epilepsy. The diet was well tolerated. Side effects included mild nausea (n=2), mild diarrhea (n= 2), and mild constipation (n=2). No subjects stopped treatment because of side effects. Mild transient hunger was experienced by 3 subjects but there was no clinically significant hunger.

The goal of the present study is to evaluate efficacy, safety and tolerability of 4:1 KD in a small number of patients with GBM progressing or recurring after standard treatment of surgery, radiation and chemotherapy with temozolamide and, after further rescue threrapy with bevacizumab (AVASTIN®), as the first step in evaluation of therapeutic potential of KD in the treatment of GBM. This will be a small, open label pilot study. 6 patients with GBM recurring or progressing after surgery, radiation and chemotherapy (temazolamide) and after further rescue treatment with bevacizumab will be treated with 4:1 [fat]:[protein+carbohydrate] ratio, 1600 kcal/day diet. Survival, time to steroid rescue treatment and progression free survival will be compared to historical controls with life expectancy of ≤ 3 months.

The diet (KD) will consist of pre-made meals, including breakfast, lunch, dinner and two snacks, one each between breakfast and lunch and lunch and dinner, with a 2 week-long meal plan consisting of different recipes for each day of the month, with repeating 2-week-long cycles. The diet will be supplemented with vitamins, calcium and phosphorus supplements to meet the requirements of US Dietary Reference Intakes (DRI) standard. Treatment will last 6 months. Primary aims of the study will be to (1) obtain pilot data on efficacy of ketogenic diet as adjunctive treatment of treatment-refractory glioblastoma multiforme, (2) evaluate the safety of ketogenic diet as adjunctive treatment of treatment-refractory glioblastoma multiforme, and (3) evaluate tolerability of ketogenic diet as adjunctive treatment of treatment-refractory glioblastoma multiforme.

Participants will be evaluated in face-to face visit during weeks 1, 2 and 4 of the study, then monthly. Primary outcome measures will include (a) survival time and (b) time to dexamethasone rescue therapy for cerebral edema, determined by treating physician, and (c) adverse events. Secondary outcome measures will include MRI progression, treatment compliance, hunger scale scores, fasting serum glucose and BOH levels.