APR-1051 - (ACESOT-1051)

June 1, 2026: Aprea Therapeutics, Inc. (NASDAQ: APRE) announced presentation of updated early data for APR-1051 (oral WEE1 inhibitor) from the ongoing first-in-human Phase 1 ACESOT-1051 study in biomarker-selected patients with advanced solid tumors, presented May 30 at the ASCO 2026 Annual Meeting (poster/Abstract #3107; data cutoff May 6, 2026).

Clinical activity: Two partial responses were reported in patients with endometrial cancers; six additional patients achieved stable disease, including patients with colorectal cancer, HPV+ head and neck squamous cell carcinoma, and endometrial cancer.

Safety/tolerability: APR-1051 was described as well tolerated across dose levels. Treatment-related adverse events occurred in 54% of patients; the most common were nausea (36%) and fatigue (14%), nearly all Grade 1–2.

PK: Exposure was dose-proportional with an approximately 18-hour half-life, supporting once-daily dosing.

Trial status/upcoming catalyst: 28 patients have enrolled across 10–300 mg once daily; dose escalation is ongoing with enrollment in the 300 mg cohort (dose level 9). Expansion is underway to at least 50 patients with uterine serous carcinoma and to patients with cyclin E-overexpressing, platinum-resistant ovarian cancer. Dose escalation and backfill expansion are expected to complete in Q2 2027 (ClinicalTrials.gov NCT06260514).