The influence of body mass index on Tumor Treating Fields therapy in patients with metastatic non-small cell lung cancer: A post-hoc and simulation analysis from the phase III LUNAR study

Introduction: In the phase III LUNAR study, overall survival (OS) with PD-(L)1 inhibitor or docetaxel was improved by adding Tumor Treating Fields (TTFields) therapy in patients with metastatic non-small cell lung cancer progressing on/after platinum-based therapy. This post-hoc analysis evaluated the effects of body mass index (BMI) on TTFields delivery. Methods: OS was assessed in LUNAR patients with BMI < 25 kg/m² versus ≥ 25 kg/m². TTFields intensity was evaluated via simulations using three array layouts in computerized phantom models with BMIs of 22, 26, and 30 kg/m². Results: In the BMI < 25 kg/m² subgroup (n = 140), median OS was 11.6 versus 8.2 months (hazard ratio [HR] 0.70 [95 % CI, 0.47─1.04]; p = 0.08) in patients treated with TTFields + PD-(L)1 inhibitor/docetaxel versus PD-(L)1 inhibitor/docetaxel, respectively. In the BMI ≥ 25 kg/m² subgroup (n = 119), median OS was 13.9 versus 10.1 months, respectively (HR 0.74 [95 % CI, 0.49─1.13]; p = 0.27). No significant interaction effect between BMI subgroups and treatment arm was identified for OS (p = 0.36). Device-related skin AEs occurred in 68 % and 64 % of BMI < 25 kg/m² and ≥ 25 kg/m² patients, respectively. Therapeutic field intensities (>1 V/cm) were achieved in all lung regions for all simulation models using appropriately sized arrays and layouts. Conclusions: In this post-hoc analysis, we found no difference in OS benefit of TTFields therapy between patients with BMI < 25 kg/m² versus ≥ 25 kg/m². Simulation data demonstrated the feasibility of delivering TTFields at therapeutic intensities to the lungs regardless of BMI.