Initial experience with scalp sparing radiation with concurrent temozolomide and tumor treatment fields (SPARE) for patients with newly diagnosed glioblastoma

Standard of care for glioblastoma includes concurrent chemoradiation and maintenance temozolomide with tumor treatment fields (TTFields). Preclinical studies suggest TTFields and radiation treatment have synergistic effects. We report our initial experience evaluating toxicity and tolerability of scalp-sparing radiation with concurrent TTFields.

This is a single arm pilot study (clinicaltrials.gov Identifier: NCT03477110). Adult patients (age ≥ 18 years) with KPS ≥ 60 with newly diagnosed glioblastoma were eligible. All patients received concurrent scalp-sparing radiation (60 Gy in 30 fractions), standard concurrent temozolomide (75 mg/m² daily), and TTFields. Maintenance therapy included standard temozolomide and continuation of TTFields. Radiation treatment was delivered through TTFields arrays. The primary endpoint was safety and toxicity for concurrent TTFields with chemoradiation in newly diagnosed glioblastoma.

We report the first ten patients on the trial. Eight were male, and two were female, with median age 61 years (range 49 to 73 years). Median KPS was 90 (range 70–90). Median follow-up was 7.9 months (2.8 to 17.9 months). Nine (90%) patients with unmethylated MGMT promotor, and one with methylated. Median time from surgery to radiation was 33 days (28 to 49 days). All patients completed concurrent chemoradiation plus TTFields without radiation or TTFields treatment interruption or discontinuation. Scalp dose constraints were achieved for all patients, with mean dose having a median value of 7.7 Gy (range 4.9 to 13.2 Gy), D20cc median 22.6 Gy (17.7 to 36.8 Gy), and D30cc median 19.8 Gy (14.8 to 33.4 Gy). Average daily use during concurrent phase had median value of 83.5% and 77% for maintenance. There was no related ≥ Grade 3 toxicity. Skin toxicity (erythema, dermatitis, pruritus) was noted in 80% of patients, however, these were limited to Grade 1 or 2 events which resolved spontaneously or responded to topical medications. Eight patients (80%) had progression, with median PFS of 6.9 months (range 2.8 to 9.6 months).

Concurrent TTFields with scalp-sparing chemoradiation is a safe and feasible treatment option with limited toxicity. Future randomized prospective trial is warranted to define therapeutic advantages of concurrent TTFields with chemoradiation.

Clinicaltrials.gov Identifier NCT03477110