460P - Exploring the efficacy and optimal timing of tumor treating fields in newly diagnosed glioblastoma: A real-world study

Background

The real-world performance of TTFields for newly diagnosed glioblastoma in the Chinese patient population, as well as if an earlier introduction at the concurrent usage with radiotherapy (RT) and temozolomide (TMZ) brings further benefit remains unclear.

Methods

This study emulates the design of the EF-14 and EF-32 randomized clinical trials. Patients with GBM who had undergone surgery from January 2019 to June 2023 were extracted from the Electronic Hospital System of 6 grade A tertiary teaching hospitals in China and followed up till January 2024. For expanded EF-14 emulation, individuals from the West China Hospital were duplicated, and each replicate was assigned to either the strategy “TTFields start during peri-RT period” or “no TTFields therapy.” For EF-32 emulation, individuals who’s had TTFields from all centers were duplicated, and assigned to “TTFields start with RT/TMZ” or “TTFields start with maintenance TMZ”. For each group, TTFields should last for at least 2 months. Replicates were censored when they failed to follow their assigned strategy, and potential selection bias was adjusted for by inverse-probability censoring weighting. Missing data were calculated by multiple imputation.

Results

Emulation of EF-14 led to 154 eligible patients (median age, 51.5 years; range, 20-80; 97 men [63%]). Real-world effect sizes of the emulated trial were close to EF-14 trial, with median overall survival from RT registration was 31.0 months in the TTFields group and 16.0 months in the non-TTFields group (HR, 0.54; 95% CI, 0.32-0.89; P = 0.017). Emulation of modified EF-32 led to 95 eligible patients (median age, 52 years; range, 21-80; 60 men [63.2%]). There was no significant difference in the duration of ovrall survival between the TTFields/RT/TMZ group and TTFields/TMZ group (median, 23.1 and 21.5 months; HR, 0.62; 95% CI, 0.28-1.39; P = 0.2).

Conclusions

Real-world data have bolstered the application of TTFields as an adjunct to the peri-RT period of the Stupp protocol. Although the difference in median overall survival between the TTFields/RT/TMZ and TTFields/TMZ groups was not statistically significant, it suggests an underlying potential to optimize treatment combinations as we anticipate the results of EF-32.

Clinical trial identification

NCT06346821, release date: April 4, 2024.

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.