BeOne Medicines Showcases Early Clinical Success of Two Innovative Breast Cancer Therapies at ASCO 2025
BeOne Medicines Ltd. a global biotechnology company dedicated to developing targeted therapies for cancer, announced promising new data from two early-stage breast cancer drug candidates during poster presentations at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago. The company unveiled preliminary clinical findings from two investigational agents in its expanding oncology pipeline: BG-C9074, a novel antibody-drug conjugate (ADC) targeting B7-H4, and BG-68501, a cyclin-dependent kinase 2 inhibitor (CDK2i) designed to overcome resistance to CDK4/6 inhibitors in hormone receptor-positive (HR+)/HER2-negative breast cancer.
The presentation of this data at ASCO 2025 marks a major milestone for BeOne, which is reintroducing itself to the oncology community under its new corporate identity. These initial clinical findings represent the first in-human results from both programs and underscore the company’s strategy to develop differentiated, biology-driven treatments for patients with limited therapeutic options.
“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’s breast cancer pipeline is strategically designed to address major unmet medical needs, including resistance to existing therapies and limited treatment options for heavily pretreated patients. The two candidates showcased at ASCO aim to improve both survival and quality of life by offering potent, targeted mechanisms of action and favorable early safety profiles.
BG-C9074: A Novel B7-H4-Targeting Antibody-Drug Conjugate
One of BeOne’s key investigational agents, BG-C9074, is a next-generation ADC designed to selectively deliver a topoisomerase I inhibitor payload to tumor cells expressing the B7-H4 protein. B7-H4, a member of the B7 family of immune checkpoint proteins, is broadly expressed across multiple tumor types, particularly breast and gynecologic cancers, making it an attractive therapeutic target.
In the first-in-human, Phase 1a dose escalation study, BG-C9074 was administered as monotherapy to 78 patients with advanced solid tumors, more than 25% of whom had breast cancer. The study aimed to assess safety, pharmacokinetics (PK), and preliminary antitumor activity. Importantly, enrollment was not restricted by B7-H4 expression levels, demonstrating the molecule’s activity even in an unselected patient population.
Among the 56 patients evaluable for efficacy, BG-C9074 achieved a confirmed overall response rate (ORR) of 16.1% (9/56; 95% CI: 7.6%–28.3%), including nine confirmed partial responses. The unconfirmed ORR reached 25.0% (14/56; 95% CI: 14.4%-38.4%), suggesting additional responses pending confirmation. The disease control rate (DCR)—which includes patients with stable disease in addition to partial responses—was an encouraging 73.2%, and the clinical benefit rate (CBR) was 17.9%.
Pharmacokinetic data showed dose-proportional increases across escalating dose levels, supporting the drug’s predictability and consistency in human subjects. Notably, these early signs of activity were seen in a heavily pretreated patient population, where treatment resistance is often a major barrier to response.
In terms of safety, BG-C9074 exhibited a manageable tolerability profile. Five dose-limiting toxicities (DLTs) were reported across three dose levels, including Grade 3 fatigue (n=1), Grade 3 febrile neutropenia (n=2), and Grade 4 thrombocytopenia (n=2). The most commonly reported treatment-emergent adverse events (TEAEs) were nausea, fatigue, and neutropenia. Grade ≥3 TEAEs were primarily neutropenia and thrombocytopenia. Importantly, there were no TEAEs that led to treatment discontinuation or death.
These findings support the continued clinical development of BG-C9074, which is being evaluated under the trial registration number NCT06233942, as a promising therapeutic option for patients with B7-H4-positive advanced solid tumors, including breast cancer.
BG-68501: Tackling Resistance with a CDK2 Inhibitor
BeOne’s second highlighted program, BG-68501, is a selective CDK2 inhibitor designed to address one of the most pressing challenges in HR+/HER2- breast cancer—acquired resistance to CDK4/6 inhibitors. CDK2 is often upregulated in tumors that become resistant to CDK4/6 inhibitors, particularly through the overexpression of cyclin E1. By directly inhibiting CDK2, BG-68501 aims to restore sensitivity and halt tumor progression.
The ongoing Phase 1a trial evaluated BG-68501 in 57 patients with advanced solid tumors, including 19 patients with HR+/HER2- metastatic breast cancer who had all received prior CDK4/6 inhibitor therapy. Patients were treated with BG-68501 either as monotherapy or in combination with fulvestrant, a selective estrogen receptor degrader (SERD), across multiple dose-escalation cohorts.
Among 37 patients evaluable for efficacy (all monotherapy recipients), the unconfirmed ORR was 5.4% (2/37; 95% CI: 0.7%–18.2%). Both responses occurred in patients with HR+/HER2- breast cancer. One of these patients remained on treatment at the time of data cutoff, indicating potential durability, while the other had discontinued. An additional 15 patients (40.5%) achieved stable disease, while another 15 (40.5%) experienced disease progression. The unconfirmed clinical benefit rate (CBR) was 8.1%, and the unconfirmed disease control rate (DCR) was 45.9%.
BG-68501 also demonstrated favorable pharmacokinetic characteristics, including linear dose-exposure relationships and signs of target engagement, as suggested by pharmacodynamic markers.
Importantly, no DLTs were observed in the dose-escalation phase, and the drug’s safety profile was deemed manageable. The most common side effects were vomiting, nausea, and fatigue, and treatment discontinuation due to adverse events occurred in only four patients (7%). No treatment-related deaths were reported.
These findings support BG-68501’s potential as a resistance-overcoming agent for HR+/HER2- breast cancer, a subtype that accounts for the majority of breast cancer diagnoses globally.
A Strategic Pipeline with Global Ambition
BeOne Medicines is positioning itself as a key innovator in oncology, with a pipeline designed to address complex resistance mechanisms and introduce more targeted and tolerable treatment options. In addition to BG-C9074 and BG-68501, the company is also advancing a proprietary CDK4 inhibitor and other targeted therapies aimed at genetically defined cancer subtypes.
By focusing on biological mechanisms that drive treatment resistance and tumor progression, BeOne aims to offer therapies that extend survival and improve the patient experience—especially in heavily pretreated populations who often face limited therapeutic choices.
BeOne’s presentations at ASCO 2025 not only mark the debut of its rebranded identity but also signal a new phase in the company’s growth as it progresses from early development into broader clinical exploration. With promising early efficacy and manageable safety profiles, both BG-C9074 and BG-68501 are poised for further clinical advancement and represent important steps forward in the fight against breast cancer.
