Mosaic Therapeutics to Present Poster Highlighting Preclinical Data for Lead Program MOS101 at the American Association for Cancer Research (AACR) Annual Meeting 2026

• First preclinical data on the Company’s lead program MOS101: a combination of ASTX295, a next-generation, clinical-stage MDM2 antagonist, and olaparib, an FDA-approved PARP inhibitor, in biomarker-selected solid tumors
• Additional data showcasing Mosaic’s Discovery Platform, PRIME, will be presented

CAMBRIDGE, England--(BUSINESS WIRE)--Mosaic Therapeutics, Ltd, (‘Mosaic’, or ‘the Company’) a clinical-stage oncology therapeutics company building the category leader in Synergistic Precision Oncology, today announced it will hold a poster presentation at the American Association for Cancer Research (AACR) Annual Meeting 2026, taking place April 17-22 in San Diego, CA.

Poster Presentation Details:

Title: "Combination of the MDM2 antagonist ASTX295 and olaparib as a novel treatment option for BRCA2 mutant, TP53 wild-type solid tumors”
Abstract Number: 3053
Date and Time: Monday, April 20, 2026, 2:00PM – 5:00PM PST
Session Category: Novel Targets and Pathways
Session: PO.ET09.09
Location: Poster Section 15

For more information and to view the Company’s abstract, visit the AACR Annual Meeting website.

About ASTX295

ASTX295 is a potent, highly selective, potentially best-in-class MDM2 antagonist that has completed a phase I study (NCT03975387) in over 100 patients with advanced solid tumors. Rationally designed to exhibit a short half-life, ASTX295 has demonstrated a compelling safety profile with minimal hematological toxicities, enabling use as a combination therapy.

MDM2 is a clinically validated target for cancer therapy, frequently overexpressed across multiple tumor types. As the primary negative regulator of the p53 tumor suppressor protein, MDM2 inhibition leads to p53 stabilization and re-activation, inducing cell cycle arrest and apoptosis.

Mosaic Therapeutics announced the in-licensing of ASTX295, alongside ASTX029 (an ERK1/2 inhibitor), from Astex Pharmaceuticals in April 2025, and holds full development and commercialization rights.

About MOS101

Plans for a Phase 1b/2a study evaluating the combination of ASTX295 with olaparib (an approved PARP inhibitor) for patients with biomarker-selected solid tumors are being finalized.

About Mosaic Therapeutics

Mosaic Therapeutics is an oncology therapeutics company building the category leader in Synergistic Precision Oncology. The company’s mission is to tackle cancers with substantial unmet need and few targeted treatment options, by reinventing the traditional approach to discovering and developing novel combination medicines.

Born out of pioneering research at the Wellcome Sanger Institute, in collaboration with the Netherlands Cancer Institute, and anchored around a proprietary platform that has seen 20 years of fine-tuning and development, Mosaic has active programs across a variety of oncology indications and disease biology pathways.

Mosaic is applying its advanced experimental and computational platform to identify oncology combinations that have synergistic activity in biomarker-defined patient populations. The Company’s pipeline is anchored by ASTX295, an MDM2 antagonist, and ASTX029, an ERK1/2 inhibitor, both in-licensed from Astex Pharmaceuticals in April 2025. Mosaic’s first clinical combination study is expected to commence in early 2027.

LinkedIn: https://linkedin.com/company/mosaic-tx

Website: https://mosaic-tx.com/