BeOne Medicines Highlights Accelerating Solid Tumor Pipeline with New Data at ASCO 2026

Oral and poster presentations span three priority programs in breast, gynecologic, and gastrointestinal cancers, advancing rapidly toward pivotal development

Company to host investor webcast showcasing momentum across solid tumor pipeline

BeOne Medicines Ltd. ("BeOne") (NASDAQ:ONC, HKEX: 06160, SSE: 688235)), a global oncology company, today announced new data from its solid tumor pipeline being presented at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting (May 29–June 2, Chicago). These data underscore the significant acceleration across the Company's high-priority breast, gynecologic and gastrointestinal (GI) cancer development programs.

Data from three differentiated BeOne pipeline assets will be presented, including:

• CDK4 inhibitor (BGB-43395) (poster presentation): First disclosure of anti-tumor activity in first-line (1L) HR+/HER2- metastatic breast cancer.
• B7-H4 ADC (BG‑C9074) (rapid oral presentation): Phase 1 dose-escalation and safety expansion data in advanced solid tumors.
• GPC3x4-1BB (BGB-B2033) bispecific antibody (rapid oral presentation): First clinical data in advanced solid tumors, including hepatocellular carcinoma (HCC), the most common type of liver cancer.

Mark Lanasa, M.D., Ph.D., Chief Medical Officer, Solid Tumors, BeOne Medicines, said: "2026 is an inflection year for BeOne's solid tumor portfolio, marked by the encouraging data we are presenting at ASCO combined with upcoming readouts at other major congresses. These programs validate our strategy of pairing the right biology with the right modality, and support advancing several assets in different indications into pivotal trials in 2026."

Selective CDK4 inhibitor shows promising efficacy and differentiated safety in first-line breast cancer (Poster Presentation: 180; June 1, 2026, 1:30 PM-4:30 PM CDT)

BeOne will present data about its highly selective CDK4 inhibitor, BGB-43395, in 1L HR+/HER2- metastatic breast cancer, in combination with letrozole, showing promising anti-tumor activity and a favorable safety profile, characterized by infrequent low-grade hematologic toxicities and manageable GI events, which were further mitigated when administered with food. Highlights include:

• The 240 mg dose of BGB-43395 plus letrozole resulted in a confirmed overall response rate (ORR) of 68.4% (95% CI: 43.4–87.4) and unconfirmed ORR of 73.7% (95% CI: 48.8-90.9).
• The 400 mg dose plus letrozole resulted in a confirmed ORR of 63.2% (95% CI: 38.4–83.7) and unconfirmed ORR of 73.7% (95% CI: 48.8-90.9).
• Low levels of hematologic treatment-related adverse events (TRAEs) with Grade ≥3 neutropenia reported in 5.3% of patients at the 240 mg dose level and 0% at 400 mg, as well as low frequency of fatigue and asthenia; supports profile and validates the molecule's high selectivity for CDK4.
• GI TRAEs were mitigated when administered with food, all of which were Grade 1.
• Median study follow-up was 12.5 (range, 3.1-15.2) months, 12.4 (range, 8.0-15.0) months, and 10.8 (range, 3.2-12.9) months for the 240 mg, 400 mg, and 600 mg dose groups, respectively.

These compelling safety and efficacy findings support the rationale to initiate a global, randomized Phase 3 clinical trial with BGB-43395 in combination with letrozole in 1L HR+/HER2- metastatic breast cancer. The trial, KANDELA-302 (NCT07492641), will begin enrolling patients this month.

B7-H4 ADC demonstrates encouraging efficacy supporting advancement in ovarian cancer (Rapid Oral Abstract: 3013; June 2, 2026, 9:45-11:15 AM CDT)

Data at ASCO from BeOne's B7‑H4-targeting antibody-drug conjugate (ADC), BG‑C9074, include results from Phase 1 dose‑escalation and safety‑expansion cohorts, demonstrating a combination of early efficacy signals and a favorable tolerability profile. Highlights include:

• At doses under consideration for future development, confirmed ORR of 45.5% and unconfirmed ORR of 54.5% in ovarian cancer (OC), and 40.0% in triple-negative breast cancer, with median study follow-up of 6.6 (range, 0.3-20.8) months.
• Anti-tumor activity demonstrated in OC regardless of B7-H4 expression level.
• Treatment was generally well tolerated with low rates of discontinuation at <5%; 31.5% of patients experienced Grade ≥3 TRAEs, with no Grade ≥3 nausea at 6 mg/kg adjusted ideal body weight (AIBW) and 1.2% at 8 mg/kg AIBW. Grade ≥3 neutropenia rates were 14.8% at 6 mg/kg AIBW and 34.6% at 8 mg/kg AIBW.
• AIBW-based dosing used in the ongoing phase 1 study of BG-C9074 effectively reduced pharmacokinetic variability compared with total body weight dosing, as presented in a separate abstract (Poster 166) at ASCO.

These results support continued advancement of the BG‑C9074 development program, with efforts focused on early‑line OC and additional B7‑H4-expressing tumor types.

Potential first-in-class GPC3x4-1BB bispecific demonstrates unprecedented anti-tumor activity in heavily pre-treated HCC patients (Rapid Oral Abstract: 3016; June 2, 2026, 9:45-11:15 AM CDT)

The first clinical data (Phase 1a) for BGB-B2033, a GPC3x4-1BB bispecific antibody, will be presented in a rapid oral session highlighting the first-in-class potential of this program in advanced solid tumors, including heavily pre-treated HCC. BGB-B2033 was rationally designed to target GPC3-expressing tumors, a protein commonly expressed in HCC, the sixth most prevalent cancer and third leading cause of cancer death worldwide,¹ with five-year survival rates of only approximately 20%.²

Highlights include:

• At doses ≥300 mg, confirmed ORR was 28.9% and unconfirmed ORR was 31.6%, with median study follow-up of 4.8 (range, 0.3-15.5) months.
• Treatment was generally well tolerated across all dose levels (1-1000 mg every three weeks [Q3W], N = 61) with no significant dose-dependent increase in rates of treatment-emergent adverse events (TEAEs):
  • 68.9% (42) of patients experienced TEAEs; of these:
    • 47.5% (29) were treatment related
    • 8.2% (5) of patients experienced Grade ≥3 TRAEs
    • 4.9% (3) were treatment-related serious adverse events
  • TEAE leading to treatment discontinuation occurred in 3.3% (2) of patients
  • Dose limiting toxicity occurred in 1.6% (1) of patients
• TRAEs that occurred in >5% of patients were limited to increases in alanine aminotransferase (ALT) and aspartate aminotransferase (AST), both occurring at Grade ≥3 in only 1.6% of patients.

With ORR levels in heavily pretreated patients on par with the current first-line immunotherapy combination standard of care and a differentiated safety profile, BeOne is moving rapidly to advance clinical development of BGB-B2033. The Company has already announced the initiation of a potentially registration-enabling pivotal study in late-line HCC and planned expansion into earlier lines of therapy and additional tumor types, with the ambition to establish a new standard of care in this difficult-to-treat cancer.

Investor webcast to highlight solid tumor pipeline data at ASCO

BeOne will hold an investor webcast at 7:00 p.m. CDT/8:00 p.m. EDT, today, June 1, 2026. The Company's leadership team, with clinical commentary by expert physicians, will highlight key solid tumor programs being presented at ASCO, share progress in BeOne's global R&D portfolio, and outline the strategies and capabilities supporting the Company's continued growth trajectory.

Webcast access details are available in the Investors section of BeOne's website at http://ir.beonemedicines.com, https://hkexir.beonemedicines.com, and https://sseir.beonemedicines.com. An archived webcast will be available on the Company's website.

About BGB-43395, a CDK4 inhibitor

BGB-43395 is an investigational cyclin-dependent kinase (CDK) 4 inhibitor being studied in a global clinical development program in hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) breast cancer. The program includes KANDELA-302 (NCT07492641), a randomized Phase 3 clinical trial, initiated in Q2 2026 in first-line metastatic HR+/HER2- breast cancer. BGB-43395 is highly potent and selective CDK4 inhibitor and has the potential to reduce the dose-limiting hematologic toxicities that exist with the current CDK4/6 standard of care and may improve tolerability and enable deeper CDK4 inhibition.

About BG-C9074, a B7-H4-targeting ADC

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. In a Phase 1 study of BG-C9074 (NCT06233942), patients with advanced solid tumors, irrespective of B7-H4 expression, received BG-C9074 every 3 weeks in escalating doses from 1 to 9 mg/kg. A subsequent safety expansion cohort received BG-C9074 in doses ranging from 4 to 8 mg/kg. Endpoints included safety, recommended dose for expansion, preliminary antitumor activity and pharmacokinetic measures.

About BGB-B2033, a GPC3x4-1BB bispecific antibody

BGB-B2033 is a bispecific antibody targeting GPC3 (glypican 3), a tumor-specific antigen highly expressed in hepatocellular carcinoma (HCC),³ and 4-1BB, a co-stimulatory receptor associated with T-cell activation and tumor reactivity in HCC.⁴ The molecule has been designed with reduced antibody-dependent cellular cytotoxicity (ADCC) to prevent systemic toxicity. BGB-B2033 is being investigated in a Phase 1 study (NCT06427941) in patients with GPC3-expressing advanced solid tumors with at least one prior line of therapy. Patients received BGB-B2033 every 3 weeks in eight escalating dose levels from 1 to 1000 mg, with various safety and anti-tumor activity endpoints. In December 2025, the FDA granted Fast Track Designation to BGB-B2033 for the treatment of HCC, followed by Orphan Drug Designation in March 2026.

About BeOne

BeOne Medicines is a global oncology company that is discovering and developing innovative treatments for 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. The Company has a growing global team spanning six continents who are driven by scientific excellence and exceptional speed to reach more patients than ever before. 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 its solid tumor pipeline; 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 achieve 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 Newsroom site.

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Investor Contact

Liza Heapes

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ir@beonemed.com

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