ACTR-52. TUMOR TREATING FIELDS (TTFIELDS) IN COMBINATION WITH LOMUSTINE (CCNU) IN THE EF-14 PHASE 3 CLINICAL STUDY – A SAFETY ANALYSIS

Abstract INTRODUCTION: TTFields are low intensity, intermediate frequency, alternating electric fields. The significant overall and progression-free survival benefit, shown in the EF-14 phase 3 study was seen in all patient-subgroups, independent of e.g. MGMT-promotor methylation-status or age. TTFields were not associated with additional systemic toxicity. At recurrence, patients were allowed to continue TTFields with second-line therapies. Here, we analyzed the safety data of TTFields + lomustine (CCNU) to evaluate safety and feasibility of this combination. METHODS Patients in the EF-14 trial received TTFields until second progression, or for 24 months. Change in chemotherapy regimen was allowed after tumor progression. We compared the patients who received lomustine as second-line chemotherapy in combination with TTFields (n=134) to the patients who received lomustine as monotherapy after first progression (n=39). We compared baseline characteristics and the adverse event profile between the groups. RESULTS Baseline characteristics were well balanced except for less female patients in the lomustine only group (7.7% vs. 22.4%). Median age in the TTFields/lomustine group was 55.5 years (29–83) compared to 50.0 years (19–71) for lomustine alone. The addition of TTFields to lomustine therapy was not associated with any significant increase in systemic adverse events compared to lomustine therapy alone (number of patients with 1 SAE 30 % vs. 31 %) and the distribution, severity and overall incidence of adverse events were not statistically different in patients in the two treatment groups. CONCLUSION: The data show that the combination of TTFields and lomustine is safe and feasible. This analysis emphasizes again the strong safety profile of TTFields and the high potential of combining TTFields with other modalities. This data is especially important in light of the recently presented, promising data from a small randomized trial that tested the combination of lomustine + TMZ in newly diagnosed (MGMT promotor-methylated only) glioblastoma patients.