BeOne Medicines Unveils Promising Clinical Data for Two Novel Breast Cancer Therapies at ASCO 2025

Preliminary results highlight anti-tumor activity and favorable safety profiles of both B7-H4-targeting ADC and CDK2 inhibitor

Data underscore strength of emerging breast cancer pipeline as part of BeOne’s global transformation with next wave of innovation

BeOne Medicines Ltd. (NASDAQ: ONC; HKEX: 06160; SSE: 688235), a global oncology company, announced new clinical data from its emerging breast cancer pipeline at the American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago. Poster presentations feature preliminary results of the dose escalation studies of two investigational molecules: BG-C9074, a novel B7-H4-targeting antibody-drug conjugate (ADC) in patients with advanced solid tumors, including breast cancer, and BG-68501, a cyclin-dependent kinase-2 inhibitor (CDK2i), in HR+/HER2- breast cancer patients with prior CDK4/6i exposure.

“Presenting the first clinical data for two novel breast cancer candidates at ASCO 2025 marks a pivotal moment for BeOne,” said Mark Lanasa, M.D., Ph.D., Chief Medical Officer, Solid Tumors at BeOne. “These early results highlight the strong potential of our B7-H4-targeting ADC and CDK2 inhibitor to address critical gaps in breast cancer treatment. Alongside our advancing CDK4 inhibitor, they represent just the beginning of a pipeline built on targeted, biology-driven innovation. As we debut our new identity as BeOne, this milestone reflects the momentum behind our science and our commitment to delivering impactful therapies to cancer patients worldwide.”

BeOne is advancing a robust pipeline of differentiated investigational medicines for breast cancer that may both effectively combat the disease and potentially improve quality of life for patients receiving treatment.

BG-C9074, a B7-H4-targeting ADC (Abstract #3033)

BeOne presented initial results of the ongoing first-in-human, Phase 1a dose escalation study of BG-C9074 monotherapy in 78 patients with advanced solid tumors, of which more than a quarter were breast cancer patients. BG-C9074, an investigational topoisomerase I inhibitor ADC that targets the B7-H4 protein, which is broadly expressed in breast and gynecologic cancers, is designed with an innovative drug linker to deliver a potent cancer-killing drug directly to the cancer cells.

With limited follow-up among the 56 efficacy-evaluable patients, preliminary clinical responses were observed at multiple dose levels across various tumor types without selection for B7-H4 expression in these heavily pretreated patients. Confirmed overall response rate (ORR) was 16.1% (9/56; 95% CI: 7.6%–28.3%), with 9 confirmed partial responses; unconfirmed ORR was 25.0% (14/56; 14.4%-38.4%) (n=14 partial responses). Confirmed disease control rate (DCR) was 73.2% (59.7%-84.2%) and confirmed clinical benefit rate (CBR) was 17.9% (8.9%-30.4%). Pharmacokinetics (PK) were observed to be approximately dose-proportional across dose levels.

BG-C9074 showed a manageable safety and tolerability profile in patients with B7-H4 advanced solid tumors, including breast cancer. There were 5 dose-limiting toxicities (DLTs) reported among 3 dose levels, all related to treatment: grade 3 fatigue (n=1); grade 3 febrile neutropenia (n=2); and grade 4 platelet count decreased (n=2). The most common treatment-emergent adverse events (TEAEs) were nausea, fatigue, and neutropenia*. The most common grade ≥3 TEAEs were neutropenia and thrombocytopenia†. There were no TEAEs leading to treatment discontinuation or death.

These data support the continued development of BG-C9074 in patients with advanced solid tumors. (NCT06233942)

BG-68501, a CDK2 inhibitor (Abstract# 3115)

Dose-escalation data from the first-in-human, Phase 1a study of a novel CDK2 inhibitor, BG-68501, were presented as a poster today. BG-68501 is designed to address elevated CDK2 activity as well as cyclin E1-driven upregulation, two key resistance mechanisms that often limit the effectiveness of CDK4/6 inhibitors in treating HR+/HER2- breast cancer. CDK inhibitors target checkpoint proteins that control cell division to stop the growth of cancer cells.

A total of 57 enrolled patients with advanced solid tumors, including 19 patients with HR+/HER2- metastatic breast cancer, received BG-68501 as monotherapy or in combination with fulvestrant in escalating dose cohorts (all received prior CDK4/6i).

Of the 37 efficacy-evaluable patients (all with monotherapy), unconfirmed overall response rate (ORR) was 5.4% (2/37; 95% CI: 0.7%–18.2%). Two extensively pretreated patients (5.4%) experienced unconfirmed partial response (PR), 15 patients (40.5%) had stable disease (SD), 15 patients (40.5%) had progressive disease (PD), and 5 patients (13.5%) were not evaluable/not assessed. Of the 2 patients with PR, both were breast cancer patients, and one was ongoing with treatment at the time of data cutoff, while the other had discontinued treatment. Unconfirmed clinical benefit rate (CBR) was 8.1% (3/37; 95% CI: 1.7%-21.9%) and unconfirmed disease control rate (DCR) was 45.9% (17/37; 95% CI: 29.5%-63.1%). BG-68501 demonstrated a linear PK profile consistent with preclinical data and signs of pharmacodynamic responses.

BG-68501 demonstrated a manageable safety and tolerability profile, with no DLTs observed to date during dose escalation. The most common TEAEs were vomiting, nausea, and fatigue, and TEAEs leading to treatment discontinuation occurred in 4 patients (7%) across all dose levels. There were no TEAEs leading to death.

The data support continued development of BG-68501 as a next-line option for tumors with CDK2 dependency. (NCT06257264)

For additional information about our presence at the 2025 ASCO Annual Meeting, please visit our meeting hub: congress.beonemedicines.com.

BeOne will host an investor R&D Day on June 26 at 8:30 am ET covering its deep and broad global innovation pipeline and platforms, as well as the Company's vision, differentiated capabilities, and value creation drivers. A live webcast will be accessible from the investors section of BeOne’s website at https://ir.beonemedicines.com, https://hkexir.beonemedicines.com, or https://sseir.beonemedicines.com. An archived replay will be available for 90 days following the event.

About Our Breast Cancer Pipeline

BeOne is advancing a robust portfolio of investigational medicines for breast cancer, including three molecules in clinical development – two cyclin-dependent kinase (CDK) inhibitors, BGB-43395, a CDK4 inhibitor, and BG-68501, a CDK2 inhibitor, and an antibody-drug conjugate (ADC), BG-C9074. BeOne also plans to evaluate the potential of BCL2 inhibition in breast cancer, with next-generation BCL2 inhibitor, BGB-21447, expected to begin clinical testing in solid tumor indications soon. Multispecific antibodies and targeted protein degraders with potential applications in breast cancer are among the preclinical assets being developed.

About Breast Cancer

Breast cancer accounts for close to one in four cancer cases and one in six cancer deaths in women worldwide.¹ Globally, breast cancer is the second most common cancer and the fourth highest cause of cancer mortality as well as the leading cause of cancer death in women.¹ More than 2.3 million patients were diagnosed with breast cancer in 2022, and over 666,000 deaths were reported globally.¹ Approximately two-thirds of breast cancer cases are the HR+/HER2- subtype.²

About BeOne

BeOne Medicines is a global oncology company domiciled in Switzerland that is discovering and developing innovative treatments that are more affordable and accessible to cancer patients worldwide. With a portfolio spanning hematology and solid tumors, BeOne is expediting development of its diverse pipeline of novel therapeutics through its internal capabilities and collaborations. With a growing global team of more than 11,000 colleagues spanning six continents, the Company is committed to radically improving access to medicines for far more patients who need them.

To learn more about BeOne, please visit www.beonemedicines.com and follow us on LinkedIn, X, Facebook and Instagram.

Forward-Looking Statement

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 and other federal securities laws, including statements regarding the potential of BeOne’s B7-H4-targeting ADC and CDK2 inhibitor to address critical gaps in breast cancer treatment; the ability of BeOne to deliver impactful therapies to cancer patients worldwide; the ability of BeOne’s pipeline to effectively combat breast cancer and improve quality of life for patients; and BeOne’s plans, commitments, aspirations, and goals under the heading “About BeOne.” Actual results may differ materially from those indicated in the forward-looking statements as a result of various important factors, including BeOne's ability to demonstrate the efficacy and safety of its drug candidates; the clinical results for its drug candidates, which may not support further development or marketing approval; actions of regulatory agencies, which may affect the initiation, timing, and progress of clinical trials and marketing approval; BeOne's ability to achieve commercial success for its marketed medicines and drug candidates, if approved; BeOne's ability to obtain and maintain protection of intellectual property for its medicines and technology; BeOne's reliance on third parties to conduct drug development, manufacturing, commercialization, and other services; BeOne’s limited experience in obtaining regulatory approvals and commercializing pharmaceutical products and its ability to obtain additional funding for operations and to complete the development of its drug candidates and maintain profitability; and those risks more fully discussed in the section entitled “Risk Factors” in BeOne’s most recent quarterly report on Form 10-Q, as well as discussions of potential risks, uncertainties, and other important factors in BeOne's subsequent filings with the U.S. Securities and Exchange Commission. All information in this press release is as of the date of this press release, and BeOne undertakes no duty to update such information unless required by law.

To access BeOne media resources, please visit our News & Media site.

*Neutropenia was defined by a custom MedDRA basket with neutropenia and neutrophil count decrease preferred terms.

†Thrombocytopenia was defined by a custom MedDRA basket with thrombocytopenia and platelet count decreased preferred terms.

¹ Bray F, et al. Global cancer statistics 2022: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer J Clin. April 4, 2024. https://doi.org/10.3322/caac.21834

² National Cancer Institute, SEER. Cancer Stat Facts: Female Breast Cancer Subtypes. https://seer.cancer.gov/statfacts/html/breast-subtypes.html Accessed November 11, 2024.

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