27 October 2025, Shanghai – Abbisko Therapeutics Co., Ltd. ("Abbisko Therapeutics" hereafter, HKEX code: 02256.HK) today announced presentation of the latest preclinical findings from two of its pipeline programs – the CDK4/2 inhibitor ABK-CDK-1 and the SMARCA2 PROTAC degrader ABK-SM2-1 – at the 37^th AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics (AACR-NCI-EORTC Conference). Both drug candidates demonstrated superior preclinical profiles.

Abbisko Therapeutics presented the following findings at the conference:

CDK4/2 Inhibitor ABK-CDK-1

Title: Discovery of ABK-CDK-1, a selective and brain penetrant CDK4/2 inhibitor to overcome resistance of CDK4/6 inhibitors in breast cancer

Session: Poster Session A

Abstract # A092

Date and Time: Thursday, October 23, 12:30pm-4:00pm (ET)

Background: Cyclin-dependent kinase (CDK) 4/6 inhibitors have demonstrated clinical efficacy in advanced breast cancer and their application has also been expanded into early-stage disease with large patient population. However, the clinical benefit of first-generation CDK4/6 inhibitors—such as palbociclib, ribociclib, and abemaciclib—is limited by CDK6-mediated toxicity and the emergence of resistance driven in part by cyclin E/CDK2 activation.

A selective CDK4/2 inhibitor that spares CDK6 and penetrates the blood–brain barrier could provide a differentiated therapeutic option, especially for patients with brain metastases or resistance to existing CDK4/6 inhibitors. Through advanced computational structural analysis and medicinal chemistry effort, we have developed ABK-CDK-1, a novel, selective and brain-penetrant CDK4/2 inhibitor. Preclinical studies demonstrate its good selectivity over CDK6, strong potency in palbociclib-resistant models, robust anti-tumor efficacy, and favorable drug-like properties.

Conclusion: ABK-CDK-1, developed by Abbisko Therapeutics, is a novel selective and brain-penetrant CDK4/2 inhibitor with the potential to address limitations of current CDK4/6 inhibitors. Its promising efficacy, selectivity, and other properties support further preclinical advancement toward clinical development.

SMARCA2 PROTAC Degrader ABK-SM2-1

Title: Discovery and characterization of a highly potent and orally available SMARCA2 PROTAC degrader

Session: Spotlight on Proffered Paper (Oral Presentation)

Presenter: Haiyan Ying

Abstract # LB-C003

Date and Time: Saturday, October 25, 11:45am-12:15pm (ET)

Background: SMARCA2 and SMARCA4 are two mutually exclusive catalytic core subunits of mSWI/SNF (BAF) complexes regulating gene expression through the remodeling of chromatin structure. SMARCA4 is highly mutated in various cancer types, including ~10% of non-small cell lung cancers. SMARCA4 demonstrated a strong synthetic lethal relationship with its paralog, SMARCA2. Therefore, therapeutic strategy of selectively degrading SMARCA2 may provide an effective treatment option for patients with SMARCA4 mutated tumors. This study describes the discovery and preclinical characterization of ABK-SM2-1, a novel, potent, selective and orally bioavailable SMARCA2 PROTAC degrader.

Conclusion: The superior preclinical profile of ABK-SM2-1 supports its advancement into preclinical development.

About Abbisko Therapeutics

Founded in April 2016, Abbisko Therapeutics Co., Ltd. (HKEX: 02256.HK), is an oncology-focused biopharmaceutical company based in Shanghai that is dedicated to the discovery and development of innovative medicines to treat unmet medical needs in China and globally. The Company was established by a group of seasoned drug hunters with rich research & development and managerial expertise from top multinational pharmaceutical companies. Since its founding, Abbisko Therapeutics has built an extensive pipeline of innovative programs focused on precision oncology and immuno-oncology.

Please visit www.abbisko.com for more information.