Aprea Therapeutics Announces Early Clinical Proof-Of-Concept in the Ongoing ACESOT-1051 Dose-Escalation Trial Evaluating WEE1 Inhibitor APR-1051, Including Partial Response Observed on First Scan

Core Insights - Aprea Therapeutics announced the first unconfirmed partial response (uPR) in a patient from its Phase 1 ACESOT-1051 study, indicating early clinical activity of APR-1051 in treating advanced solid tumors [1][2] Group 1: Clinical Trial Results - The uPR was observed in a patient with PPP2R1A-mutated uterine serous carcinoma, showing a 50% reduction in target lesion size and a decrease in CA-125 levels from 732 to 70 U/mL after treatment with APR-1051 at the 150 mg dose level [2][7] - Earlier cohorts in the ACESOT-1051 study reported stable disease in multiple patients, including a 5% reduction in tumor burden in a patient with HPV-positive head and neck squamous cell carcinoma and a 15% reduction in a patient with FBXW7-mutated colon cancer [3] - The ongoing dose-escalation study is currently enrolling patients in the 220 mg cohort, with plans to increase enrollment of HPV-positive patients [4][6] Group 2: Drug Mechanism and Strategy - APR-1051 is a small-molecule inhibitor of WEE1 kinase, designed to exploit cancer-specific vulnerabilities while minimizing damage to healthy cells [8][9] - The company aims to target cancers with specific genomic alterations, including mutations in PPP2R1A, FBXW7, CCNE1, TP53, and KRAS, reinforcing the potential of APR-1051 as a differentiated treatment option [5] Group 3: Future Outlook - Aprea Therapeutics plans to provide additional updates in the first half of 2026 and complete dose escalation later in the year, indicating ongoing commitment to the development of APR-1051 [5]