Tuvusertib in Astrocytoma With ATRX Mutation

The TUVASTRAT study is a phase 2, non-randomized, two.cohort, CRS clinical trial of tuvusertib in patients with first recurrence of IDH1/2-mutated, ATRX-mutated and p53-mutated astrocytoma (Grade 2-4 from WHO classification). The mutational status of IDH (required for diagnosis) is also required. CDKN2A and ATRX will be also determined locally as per standard of care. All enrolled patients should have received first-line chemotherapy and have reported a contrast enhanced PD. Eligible patients are enrolled in two cohorts depending on their eligibility to undergo rescue surgery: * Cohort A: First recurrence of IDH1/2-mutated, ATRX-mutated astrocytoma NOT eligible for rescue surgery. * Cohort B: First recurrence of IDH1/2-mutated, ATRX-mutated astrocytoma candidates to rescue surgery. The primary hypothesis is that treatment with tuvusertib, an ATR inhibitor, will improve the efficacy outcomes and increase the 6-months PFS rate from 45% reported by the standard therapies up to 65% in patients with recurrent IDH-mutated astrocytomas with ATRX mutation. Clinic visits will occur every 3 weeks ±3 days. Tumor assessments by MRI according to RANO 2.0 criteria will be performed at baseline, and every 12 weeks +/-2 weeks (Q12W) until PD, patient withdrawal, start of new treatment line or death. This schedule must be maintained regardless of any delays in dosing. After the first suspect of progression, we recommend a second MRI at 4-8 weeks to confirm the progression, except if there is clinical progression. The MRI imaging will be assessed by PI and central radiologists. The trial includes the assessment of safety (AEs, comorbidities) throughout the study period at every visit, the collection of health-related patient reported outcomes through validated questionnaires at baseline, coincident with the tumor assessments and at the safety visit. Neurologic / neurocognitive status will be assessed through validated tests administered by the physicians. Additionally, ATRX, IDH, P53 and CDK2A mutations will be centrally reviewed in tumor biopsies or archival tumor tissue obtained as close as possible to the baseline. PKs will be determined in sparse peripheral blood samples during the treatment phase. The study includes a data safety monitoring committee (DSMC) to regularly review safety and efficacy. The DSMC will review efficacy and safety at least yearly and more frequently if deemed necessary.