ERGO: a pilot study of ketogenic diet in recurrent glioblastoma

Abstract

Limiting dietary carbohydrates inhibits glioma growth in preclinical models. Therefore, the ERGO trial (NCT00575146) examined feasibility of a ketogenic diet in 20 patients with recurrent glioblastoma. Patients were put on a low-carbohydrate, ketogenic diet containing plant oils. Feasibility was the primary endpoint, secondary endpoints included the percentage of patients reaching urinary ketosis, progression-free survival (PFS) and overall survival. The effects of a ketogenic diet alone or in combination with bevacizumab was also explored in an orthotopic U87MG glioblastoma model in nude mice. Three patients (15%) discontinued the diet for poor tolerability. No serious adverse events attributed to the diet were observed. Urine ketosis was achieved at least once in 12 of 13 (92%) evaluable patients. One patient achieved a minor response and two patients had stable disease after 6 weeks. Median PFS of all patients was 5 (range, 3-13) weeks, median survival from enrollment was 32 weeks. The trial allowed to continue the diet beyond progression. Six of 7 (86%) patients treated with bevacizumab and diet experienced an objective response, and median PFS on bevacizumab was 20.1 (range, 12-124) weeks, for a PFS at 6 months of 43%. In the mouse glioma model, ketogenic diet alone had no effect on median survival, but increased that of bevacizumab-treated mice from 52 to 58 days (p<0.05). In conclusion, a ketogenic diet is feasible and safe but probably has no significant clinical activity when used as single agent in recurrent glioma. Further clinical trials are necessary to clarify whether calorie restriction or the combination with other therapeutic modalities, such as radiotherapy or anti-angiogenic treatments, could enhance the efficacy of the ketogenic diet.

Figures

Figure 1.

Study design and course of treatment. (A) After study inclusion, patients were treated with the ketogenic diet. At 6 weeks on the diet or in the presence of clinical signs of deterioration, MRI was performed. In case of at least stable disease, diet was continued. In case of a progression, the patients were offered salvage therapy while continuing the diet. (B) Flowchart diagram showing the course of dietary treatment in the 20 included patients.

Figure 2.

Urine ketosis. The fraction of ketone body-positive urine analyses (ketone bodies >0.5 mmol/l) is reported in the 13 patients with these tests available. Each bar represents the value of one patient, sorted from lowest to the highest ratios (left to right). The individual values are also presented above each bar.

Figure 3.

Patients’ self reported rating of diet tolerability. The patients were asked to fill out a self-reported questionnaire for possible diet-related side-effects once every week on diet. These sheets were completed at least once in 12 patients. Shown are the ratings of each patient in the categories diarrhea (A), constipation (B), hunger (C) and demand for glucose (D) in every week (dot) and the mean value of these ratings in the corresponding week (line). The scale was defined as follows: 0, not present; 1, weak; 2, moderate; 3, strong. Questionnaires were available in 7–11 patients at the shown time-points.

Figure 4.

MRI finding in 3 patients. (A) T1-weighted images after intravenous application of gadolinium-DTPA (Gd-DTPA) before (left panel) and after 6 weeks on the ketogenic diet (KD) (right panel) in axial (upper) and coronar (lower) planes of the patient with a minor response. (B) T1-weighted images after intravenous application of Gd-DTPA before (left panel) and after 6 weeks on the ketogenic diet (right panel) in axial directions of a patient with stable disease. (C) Fluid-atenuated inversion recovery (FLAIR) images and T1-weighted images after application of Gd-DTPA before (left panel) and 6 weeks after start of bevacizumab (BEV) in a patient with partial response to bevacizumab who continued the diet.

Figure 5.

Analysis of PFS. (A) PFS of patients on diet who achieved stable ketosis as defined as urine ketosis in >50% of measurements (n=8) compared to those patients who did not achieve stabile ketosis (n=5) was analysed by Kaplan-Meier analysis (p=0.069, log-rank-test). (B) PFS of patients who received bevacizumab while on ketogenic diet (n=7) vs. a cohort of patients who were treated in the same period of time with bevacizumab but without ketogenic diet (n=28) (p=0.38, log-rank test).

Figure 6.

Mouse xenograft experiments. (A) 3-OHB levels in the blood were determined 24 days after U87MG tumor cell inoculation in mice on standard diet (SD) or ketogenic diet (KD) treated with PBS (control) or bevacizumab (BEV). (B) Kaplan-Meier analysis of the treatment groups. (C) At day 28 after tumor cell inoculation, 3 mice per group were analysed by MRI. Upper panel, representative T2-weighted images and T1-weighted images after infusion of Gd-DTPA are shown. Lower panel, tumor volumes were measured as described, and individual (dot) and mean values (bar) are indicated. (D) Upper panel, representative hematoxylin-eosin stainings (H&E) and color-coded distribution of ATP concentrations in representative slices. Lower panel, ATP content in the tumor areas was quantified, and individual (dot) and mean values (bar) are shown.