On May 6, the website of the National Medical Products Administration (NMPA) showed that the second indication for Culmerciclib Capsules (Saitanxin^®), independently developed by Chia Tai Tianqing, the core enterprise of Sino Biopharm (1177.HK), has been approved for marketing. It is to be used in combination with fulvestrant for the initial endocrine therapy of patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative locally advanced or metastatic breast cancer. Last December, the indication for Culmerciclib for the second-line treatment of advanced breast cancer was approved for marketing, making it the world's first approved CDK2/4/6 inhibitor. The approval of this new indication is mainly based on data from the CULMINATE-2 study. 

 

 

Breast Cancer Treatment Landscape May See a "Generational Shift"

 

The CULMINATE-2 study is the world's first Phase III trial of a CDK2/4/6 inhibitor combined with endocrine therapy for the first-line treatment of HR+/HER2- advanced breast cancer to achieve positive results. At the 2025 European Society for Medical Oncology (ESMO) Congress, the results of the CULMINATE-2 study were first announced as a Late-Breaking Abstract (LBA) report^[1]:

 

● The mPFS for Culmerciclib plus fulvestrant versus placebo plus fulvestrant was NE (24.90 months, NE) vs. 20.17 months (14.78 months, NE), with a 44% reduction in the risk of disease progression or death (HR=0.56, p=0.0004). The ORR and DOR were significantly improved compared to the control group; a more significant PFS benefit was shown in subgroups with poor prognosis, such as those with visceral metastasis and liver metastases. 

 

● The most common treatment-related adverse events with Culmerciclib combination were mostly Grade 1-2 and manageable; Grade ≥3 myelosuppression toxicities such as neutropenia were only 20.3%; the rate of therapy cessation was low (3.5%), and the safety of long-term medication was controllable and manageable. 

 

Breast cancer is the "number one cancer" among women globally and in China. HR+/HER2- breast cancer is the most common subtype, accounting for about 65%-70% of all breast cancer cases^[2]. Guidelines such as the Chinese Society of Clinical Oncology (CSCO) Breast Cancer Guidelines (2025) recommend CDK4/6 inhibitors in combination with endocrine therapy as the first-line treatment for advanced HR+/HER2- breast cancer^[3,4]. However, the subsequent issues of drug resistance and toxicity have become pressing clinical problems to be solved. 

 

CDK6 is an essential molecule for the proliferation and differentiation of hematopoietic stem cells. Its inhibition leads to an abnormal decrease in neutrophil levels, increasing the risk of infection, which clinically requires mitigation through drug discontinuation, dose adjustment, or injection of granulocyte colony-stimulating factor (GCSF). By enhancing the selective inhibition of CDK2 and CDK4 while reducing the inhibition of CDK6, Culmerciclib is mechanistically expected to delay or overcome drug resistance mediated by compensatory activation of CDK2, while achieving a balance between anti-tumor effects and bone marrow safety^[5]. With the approval of this first-line indication, Culmerciclib is expected to bring new treatment options to a broader range of patients with its clinical potential for deeper remission and lower toxicity. 

 

Leveraging "Mechanism Innovation" to Drive "Full-Spectrum Layout"

 

Culmerciclib has great clinical potential, and indications covering the entire treatment cycle of breast cancer are being developed simultaneously. Among them, the indication for combination with fulvestrant for HR+/HER2- breast cancer with disease progression after prior endocrine therapy was approved for marketing in China in December 2025; a Phase III clinical trial for adjuvant treatment of early-stage HR+/HER2- breast cancer is progressing smoothly and is expected to further expand its clinically benefiting population. 

 

Focusing on the field of breast cancer treatment, Sino Biopharm has established a layout covering all molecular subtypes, including HER2+, HER2-low, HR+/HER2-, and triple-negative breast cancer (TNBC). In terms of the treatment cycle, it systematically covers the entire spectrum of treatment scenarios from neoadjuvant therapy, adjuvant therapy, to advanced first-line, second-line and above therapy, striving to provide new treatment options for more patients. 

 

In the field of HR+/HER2- breast cancer treatment, in addition to Culmerciclib, the company has also made a differentiated layout of products such as TQB3126 (ER-PROTAC), TQB3122 (PARP1 inhibitor), and TQB2101 (ROR1 ADC). Currently, TQB2102 (an HER2 bispecific ADC) for the treatment of breast cancer has been granted Breakthrough Therapy Designation twice. Enrollment for the Phase III clinical trial for developing indications such as HER2-low and HER2+ advanced breast cancer has been completed. Similarly, TQB2930 (an HER2 bispecific antibody), also for the treatment of HER2+ breast cancer, is in the Phase III clinical research stage. 
With the advancement of more potential pipelines, Sino Biopharm is poised to reshape the entire breast cancer treatment landscape with its product matrix covering all subtypes and the full cycle of treatment. 

 

References:

 

[1] Erwei song, et al.Culmerciclib plus fulvestrant as first-line treatment for HR+/HER2- advanced breast cancer cancer:A phase 3 trial(CULMINATE-2),ESMO 2025 LBA25.

[2] Wu Hao, Lyu Qing. Epidemiological trends of breast cancer globally and in China and implications for prevention and control: An interpretation of the "Global Cancer Statistics Report" 2018-2022 [J]. Chinese Journal of Bases and Clinics in General Surgery, 2024, 31(07):796-802. 

[3] National Comprehensive Cancer Network.NCCN Clinical Practice Guidelines in Oncology (NCCN Guideline).Breast Cancer, version 5.2023[EB/OL].[2024-01-12]. 

[4] Chinese Society of Clinical Oncology Guidelines Working Committee. Chinese Society of Clinical Oncology Guidelines for the Diagnosis and Treatment of Breast Cancer 2025 [M]. Beijing: People's Medical Publishing House. 

[5] Xu Z, Liu Y, Song B, et al.Discovery and preclinical evaluations of TQB3616, a novel CDK4-biased inhibitor.Bioorganic & Medicinal Chemistry Letters 2024; 107.

 

Declaration:

 

1. This press release is intended to facilitate the communication and exchange of medical information and is for reference by healthcare professionals only. It is not for advertising purposes. 

2. The company does not recommend any drugs and/or indications. 

3. The information contained in this press release is for reference only and cannot replace professional medical guidance in any way, nor should it be considered as a diagnosis or treatment recommendation. If you wish to understand specific disease diagnosis and treatment information, please follow the advice or guidance of a physician or other healthcare professional. 

 

Forward-Looking Statements:

 

This press release contains certain forward-looking statements, including statements regarding the clinical development plan, expected clinical benefits and advantages, commercialization prospects, the possibility of clinical benefit to patients, and potential commercial opportunities for [Cumociclib Capsules (Saitanxin®)]. Words such as "expect", "believe", "continue", "may", "estimate", "hope", "intend", "plan", "potential", "predict", "project", "should", "will", "propose", and similar expressions are intended to identify forward-looking statements, but not all forward-looking statements contain these identifying words. These forward-looking statements are predictions or expectations made by the company based on currently available data and information, and actual results may differ materially from these forward-looking statements due to uncertainties or risks such as policy, R&D, market, and regulatory factors. Current or potential investors are advised to carefully consider the potential risks and should not place undue reliance on the forward-looking statements in this press release, which contain information only as of the date of this press release. Unless required by law, the company undertakes no obligation to update or revise any forward-looking statements in this press release as a result of new information, future events, or other circumstances.