The TAC-GReD trial: The combination of talazoparib and carboplatin in DNA damage repair deficient recurrent high-grade glioma.

Abstract

2047 Background: Recurrent high-grade glioma (rHGG) has a dismal prognosis with limited treatment options. Given that a high proportion of these gliomas harbor deficiencies in the DNA damage repair (DDRd) pathway, this genomic occurrence may confer synergistic lethality and sensitivity to poly (ADP-ribose) polymerase (PARP) inhibitors. Therefore, we hypothesize that DDRd rHGG may be sensitive to the combination of a PARP inhibitor, talazoparib, and carboplatin. Methods: This is a prospective phase II, single-arm open-label biomarker stratified single-institution trial conducted in Hong Kong (NCT04740190). Tumor tissue was sent for comprehensive next-generation sequencing (C-NGS) to screen for genomic aberrations associated with the DDRd pathway. Patients with rHGG (WHO grade III-IV) and at least one pathogenic mutation in the DDR pathway were deemed eligible. Patients were initially treated with whole-brain radiotherapy (2 Gy/1 Fr) on C1D1. Starting at dose level 0, talazoparib (0.75mg on Days 1-4) and carboplatin (AUC 1.5 on Day 1), were administered weekly for a total of 18 cycles, followed by maintenance talazoparib. The primary endpoint was the 6-month progression-free survival (PFS-6). Results: 61 patients were screened and 33 patients with DDRd rHGG were enrolled, 23 males, 10 females, and a median age of 55 years (range: 29-70 years). 73% (n=24) had a baseline ECOG PS of 0-1. Among the recruited patients, 12% (n=4) were classified as WHO grade III, while the remaining 88% (n=29) were WHO grade IV. Dose level escalation was achieved in 27% (n=9) of the cohort. The 6-PFS was 29% (95% CI 16.2-51.9%) and the median PFS was 3.5 months (95% CI: 2.4-6.3 months). The OS at 3 and 12 months were 90.4% (95% CI 80.7-100%) and 30% (95% CI 17-53%), respectively. The most common grade 3-4 toxicities were neutropenia (21.2%, n=7), thrombocytopenia (18.2%, n=6) and anemia (9.1%, n=3). One patient developed a grade 4 thromboembolic event. Dose level reduction was implemented in 54% (n=18) of patients and treatment was terminated in 6.1% (n=2) due to toxicity. Conclusions: Talazoparib and carboplatin in a DDRd-enriched rHGG is feasible and tolerable. Additional analysis including correlation of biomarkers with long-term outcomes is underway. Clinical trial information: NCT04740190 .