On July 30, 2026 Aprea Therapeutics, Inc. (Nasdaq: APRE) ("Aprea", or the "Company"), a clinical-stage precision medicine oncology company focused on the discovery and development of targeted therapies for patients with biomarker-defined cancers, reported an update on the ongoing Phase 1 dose escalation ACESOT-1051 trial of its oral WEE1 inhibitor APR-1051.

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This latest corporate update builds on the positive progress in ACESOT-1051 to date in which APR-1051 demonstrated early signs of single-agent activity along with a favorable tolerability profile in patients with difficult-to-treat cancers.

Next Clinical Update and Accelerating Enrollment

Aprea expects to report the next clinical data update from ACESOT-1051 at a medical meeting in the fourth quarter of 2026. Enrollment is accelerating ahead of this anticipated clinical catalyst, with the number of active clinical sites expanding from three to ten. Aprea expects enrollment to reach 6 to 10 patients per month by Q4 of 2026, potentially increasing the pace of clinical data generation. The Company also plans to broaden the development by advancing APR-1051 into combination regimens, expanding the current study to include arms enrolling HPV-positive head and neck squamous cell carcinoma and colorectal cancer in combination with standard-of-care therapies.

"Expanding enrollment and adding combination regimens in HPV positive head and neck cancer and colorectal cancer will broaden the clinical dataset as we advance development of ACESOT-1051," said Gene Kennedy, M.D., Chief Medical Advisor of Aprea. "We look forward to sharing the next set of data from the trial at a medical meeting in the fourth quarter of this year,"

As previously announced, the Company is expanding enrollment to include at least 50 patients with uterine serous carcinoma or cyclin E-overexpressing, platinum-resistant ovarian cancer. Completion of dose escalation and backfill expansion is anticipated in the second quarter of 2027. This expansion is intended to further characterize the clinical activity of APR-1051 in biomarker-defined tumor populations with a mechanistic rationale for WEE1 inhibition.

Planned Combination Development

Aprea’s plans to evaluate APR-1051 in combination settings are supported by preclinical synergy observed in relevant disease models. In HPV-positive head and neck squamous cell carcinoma, the Company plans to combine APR-1051 with immune checkpoint therapy. In colorectal cancer, the Company plans to combine APR-1051 with standard-of-care chemotherapy.

The Company intends to advance dose levels that have already cleared safety review and shown single-agent activity into the planned combination regimens. This provides an appropriate starting point to establish the preliminary safety and preliminary efficacy of these regimens. In preclinical models, APR-1051 has demonstrated antitumor activity in combination with chemotherapy and with immuno-oncology agents, providing a rationale for the planned clinical combinations.

About ACESOT-1051 and Trial Design

ACESOT-1051 is a multi-center, open-label Phase 1 study evaluating oral, single-agent APR-1051 administered once daily in 28-day cycles. Part 1 is a dose escalation and dose backfill expansion of up to 100 patients, using accelerated titration at lower dose levels followed by a Bayesian optimal interval (BOIN) design. Part 2 is a dose selection optimization stage of up to 80 patients that will randomize patients 1:1 to two selected doses, to determine the recommended Phase 2 dose (RP2D).

Dose levels considered in the protocol range from 10 mg to 500 mg. Dose escalation is currently enrolling at the 300 mg cohort. Eligible patients are adults with advanced solid tumors harboring cancer-associated gene alterations, including uterine serous carcinoma regardless of biomarker status; cyclin E-overexpressing, platinum-resistant ovarian cancer (PROC); tumors harboring CCNE1, CCNE2, FBXW7, or PPP2R1A alterations; HPV-positive oropharyngeal, cervical, vaginal, or vulvar carcinoma; and KRAS- and TP53-mutated colorectal cancer.

The primary objectives are safety, dose-limiting toxicity, maximum tolerated or maximum administered dose, and RP2D. Secondary objectives include pharmacokinetics and antitumor activity assessed by RECIST/PCWG3.

The most recent update from the ACESOT-1051 trial was presented at the ASCO (Free ASCO Whitepaper) 2026 annual meeting; a copy of the poster can be found on the Aprea corporate website here.

For more information on ACESOT-1051, refer to ClinicalTrials.gov NCT06260514.

(Press release, Aprea, JUL 30, 2026, View Source [SID1234669562])