Aprea Therapeutics, Inc. announced that the Safety Review Committee (SRC) overseeing the ongoing ABOYA-119 clinical trial has determined that dosing of patients with ATRN-119 at 800 mg once daily (Cohort 6) can commence and that Cohort 6 is open for enrollment. This decision follows review of the safety and pharmacokinetic data from patients treated at 550 mg once daily (COHort 5). ABOYA-119 is a Phase 1/2a multi-center, open-label, dose-escalation and expansion clinical trial designed to test ATRN-119 monotherapy in patients with advanced solid tumors harboring defined mutations in DDR pathways.

Part 1 (Phase 1) of the study is assessing tolerability, pharmacokinetics, recommended Phase 2 dose (RP2D) and analysis of patient biomarkers. A total of 17 patients have been enrolled in the first five cohorts of the dose escalation stage (50 mg once daily, 100 mg once daily, 200 mg once daily, 350 mg once daily, and 550 mg once daily). Based on the safety profile, in March 2024 Aprea submitted an amendment to the FDA for the additional cohorts of 1,100 mg and 1,300 mg, with the goal of dosing patients in up to eight cohorts in total.

Preliminary signs of clinical benefit have been observed with two patients (data cutoff of March 12, 2024) achieving stable disease (SD) - one in the 50 mg once daily cohort and a second patient who showed longer duration when treated at 200 mg once daily. Cancers with mutation in DDR-related genes represent a high unmet medical need and these patients have poor prognosis and, currently, have no approved effective therapies. The data demonstrate near dose proportional exposure following oral administration of ATRN-119 doses between 50 mg once daily to 550 mg once daily.

Aprea has completed all IND enabling studies for its oral, small molecule WEE1 inhibitor, APR-1051, and recently received FDA clearance of its IND.