Study findings suggest adding noninvasive tumor treating fields (TTFields) prior to and during radio-chemotherapy is well tolerated in adult patients with newly diagnosed glioblastoma. These findings were presented by lead author Seid Kebir, University Duisburg-Essen, Essen, Germany at the 2023 American Society of Clinical Oncology (ASCO) Annual Meeting.

The phase 1/2 PriCoTTF study enrolled 33 patients. Patients received post-surgical TTFields therapy alongside radio-chemotherapy and adjuvant chemotherapy administered via scalp arrays for a duration of 9 months. In the event of disease recurrence, patients were permitted to re-initiate TTFields therapy. Most patients displayed typical baseline characteristics for glioblastoma at trial enrollment, except for 7 (22.5%) patients with gross total resection.

The study’s primary end points included safety and tolerability, which were compared to pre-selected treatment-limiting toxicities. At the data cutoff point, the median duration of TTFields therapy was 8.4 months. Despite 48% of events occurring, median overall survival (OS) was not achieved, preventing the development of an efficacy conclusion.

Multivariable Cox regression showed that OS was independently associated with the amount of time a patient achieved >23 hours of TTFields therapy (hazard ratio, 0.96; 95% confidence interval, 0.93 to 0.99; P = .008).

The frequency of grade ≥3 adverse events (AEs) was consistent with that of other glioblastoma studies, however in this investigation, grade ≥3 AEs occurred in 2 patients (6%) and patients did not develop treatment-limiting toxicities. Additionally, the development of high-grade skin toxicities was rare.

“Longer follow up is needed to estimate the efficacy of TTFields therapy in this setting and will need to consider the relatively low overall duration of TTFields therapy and proportion of patients who received [Guided Tissue Regeneration],” concluded Dr Kebir and coauthors.

Source:

Kebir S, Lazaridis L, Schmidt T, et al. Safety and efficacy of tumor treating fields (TTFields) prior and concomitant to radiotherapy in patients with newly diagnosed glioblastoma: Results from PriCoTTF. Presented at 2023 ASCO Annual Meeting; June 2-6, 2023; Chicago, IL. Abstract 2050