In December 2025, the world's first CDK2/4/6 inhibitor culmerciclib was approved by China's National Medical Products Administration (NMPA), attracting considerable attention within the industry. On the surface, this is a first-in-class (FIC) innovative drug successfully developed by Chia Tai Tianqing Pharmaceutical Group Co., Ltd., a subsidiary of Sino Biopharmaceutical Limited. From a deeper perspective, this breakthrough also offers many industry insights.

The CDK4/6 inhibitor field is not a niche sector. To date, 11 related products have been launched globally and nine in China. With a large number of generics present, the track has long been in a state of saturated competition. However, it was precisely within such limited room for innovation that culmerciclib broke through.

As more and more candidates are validated and competition intensifies, the key to breaking the deadlock ultimately returns to clinical value. Precisely because of this, the approval of culmerciclib is not just about a FIC label. What is determinant is how innovation can still raise the ceiling of treatment and leverage incremental clinical value in a relatively mature field.

As part of its Decision Makers DeepTALK column, PharmCube interviews on this topic Wei Zhao, Senior Vice President and Dean of the Research Institute at Chia Tai Tianqing.

Building a FIC Drug Despite Uncertainty

Zhao admits that the initial project not only aimed at a FIC label but was based on a very practical observation: CDK4/6 inhibitors are a highly valuable approach in breast cancer treatment, but efficacy and resistance bottlenecks still exist. «Our goal was to develop a molecule with more differentiated advantages», he notes.

Against this background, the potential value of CDK2 began to be re-examined. Basic research suggested that CDK2 might be involved in various tumour mechanisms and related to resistance pathways, but for a long time, this remained a hypothesis. Clinically, there were no approved drugs targeting CDK2. Choosing to include it as a research target meant the project was high-risk from the very beginning.

No innovative drug can see the finish line immediately upon project design. Looking good in pre-clinical stages is often just the beginning of a long trial-and-error process. Even after entering human trials, uncertainty remains, an unavoidable rule in innovative drug R&D.

The real turning point came from clinical results. «Preclinical data showed that culmerciclib had varying degrees of inhibitory effects on CDK2, CDK4 and CDK6 kinases, but whether it could deliver on its designed advantages and potential in a clinical setting — before Phase I data was available — we did not have complete certainty», Zhao recalled. «It was not until the Phase I results were released, and through horizontal comparative analysis with multiple CDK4/6 inhibitors, where we observed its efficacy advantages, that we truly gained confidence».

As the Phase III clinical research deepened further, the value of culmerciclib was further validated. For patients with HR+/HER2- advanced breast cancer previously treated with endocrine therapy, the median progression-free survival (mPFS) for the culmerciclib plus fulvestrant group reached 16.62 months (HR=0.36, p<0.0001). Compared horizontally with historical data, its objective response rate (ORR) was the only one exceeding 40% in similar studies.

Notably, this study also included high-risk patients with primary resistance to endocrine therapy, who are typically cautiously avoided by other trials, yet they still experienced benefit. Furthermore, studies have shown that a considerable proportion of patients who developed resistance to previous CDK4/6 inhibitor therapy can respond positively to culmerciclib. These are long-standing concerns within the existing treatment system.

It can be said that the significance of culmerciclib is not just the launch of another FIC drug, but lies in the path it represents: returning to the mechanism itself amidst uncertainty, guided by clinical value, and gradually opening new possibilities through repeated data validation.

Finding Opportunity through Mobile Warfare

With the launch of innovative drugs such as culmerciclib, Chia Tai Tianqing has also grown and transformed throughout this process, gradually accumulating a set of R&D insights.

Within its R&D system, innovation has never been an all-or-nothing gamble, but rather a form of mobile warfare requiring continuous calibration of direction and flexible adaptation. One of the core principles is that promising candidate drugs enter clinical trials as early as possible, with real efficacy and safety serving as the most important basis for decision-making. Only those showing an advantage compared to standard therapy are worth continued investment; if the signal is insufficient, the stop button is pressed. This dynamic decision-making mechanism avoids the long-term consumption of resources on low-probability projects and allows truly promising molecules to receive more concentrated support.

Simultaneously, deep interaction with clinical and other field experts is an indispensable part of the process. «The R&D team is very familiar with pharmacy and mechanisms of action, but it is often clinicians who sense earliest whether a product has potential», Zhao elalborates. «This was also the case with the development of [tyrosine kinase inhibitor] anlotinib. When we were conducting dose-escalation and exploratory studies, at a time when there were fewer drugs available, experts enrolled patients with difficult and complicated conditions. The result was discovering efficacy across various tumour types. In fact, many research directions were also identified from this experience».

Beyond methodology, what is even more commendable is the courage to make decisions and the sense of responsibility behind them. The R&D process for culmerciclib was not smooth sailing. Zhao indicated that the company internally discussed multiple times whether to pursue the adjuvant therapy indication. This study would need to enrol two to three thousand subjects, an investment amounting to several hundred million or even over a billion RMB (about USD 140 million) along with the associated risk. This is not an easy choice for most companies. Chia Tai Tianqing ultimately decided to continue the investment, showcasing the vision required in R&D decision-making.

Furthermore, changes in China's regulatory environment are also pushing innovation towards higher standards. Now, regulatory requirements are not limited just being novel; they demand proof of superiority compared to the latest standard therapy. This is what constitutes high-quality innovation and is the basic condition for the approval of innovative drugs. This brings greater benefit for patients, promoting further upgrades to the entire treatment regimen. However, it also presents an immense challenge for companies: the development window is narrowing amidst the rapid iteration within treatment fields. Culmerciclib precisely seized this window of opportunity, entering the market with a strategy of rapid commercialisation.

One Drug, The Full Picture

The recent authorisation and launch of culmerciclib provides an excellent observation perspective, offering a picture of the innovation evolution and strategic layout of parent company Sino Biopharm by zooming out from this specific start point.

Prior to this approval, Chia Tai Tianqing had already established a solid foundation in the breast cancer field through generic drugs such as fulvestrant, as well as biosimilars like trastuzumab and pertuzumab. This stage was more akin to capability accumulation, deepening the understanding of clinical needs and insights into R&D opportunities on one hand, and honing a more mature commercialisation system on the other.

The advent of culmerciclib marks a qualitative leap in Chia Tai Tianqing's innovation journey within the breast cancer field. Taking this as a core pivot point, the company continues to expand the boundaries of innovation, incorporating next-generation technologies such as the HER2 bispecific antibody-drug conjugate (ADC) TQB2102 into its pipeline, gradually building a product matrix covering different subtypes and treatment stages. Breast cancer has already become a core area where Chia Tai Tianqing deploys significant resources and accumulates an increasingly comprehensive product matrix.

This change did not occur in isolation. In recent years, the proportion of revenue from innovative products at Chia Tai Tianqing has been continuously increasing, gradually transforming into the main growth driver. Zhao explains, «In recent years, we have undergone a transition from combinations and generics to innovative medicines. As novel drugs successively enter the harvest period, the rising sales proportion will inevitably occur, and this trend is becoming increasingly apparent now. Within the last half-year to a year, among our newly initiated projects, the number of innovative drugs has already held an overwhelming advantage».

«Over the past five years, Chia Tai Tianqing's proportion of R&D investment dedicated to innovative drugs has exceeded 85%. At the same time, team building and development is another key factor, which has also led to our self-developed products gradually becoming the mainstay, accounting for as high as 70% to 80% [of our pipelines]», Zhao added.

While strengthening internal R&D, the group has simultaneously accelerated its pace in external cooperation and global expansion, becoming another focal point of its development strategy. A series of strategic decisions, such as a partnership with Boehringer Ingelheim and the acquisition of LaNova Medicines by Sino Biopharm, have not only enriched the innovative pipeline but also introduced a large number of high-end talents and teams. Sufficient exchange and knowledge sharing among various Sino Biopharm subsidiaries, including Chia Tai Tianqing, has further driven the growth of the internal R&D teams.

An international presence is of great significance for product innovation. Firstly, it represents a shift in mindset, and secondly, it involves a change in working methods. Zhao remarks, «Fortunately, within our current pipeline, multiple products are being closely watched by multinational corporations (MNCs). Over the past decade or so, we have transitioned from generic drugs to innovative drugs, which has also laid the foundation for orienting our innovation capabilities towards the world. Becoming an international pharmaceutical company is a process, but we are moving towards that goal».

Conclusion

Despite the constantly changing domestic regulatory, market, and reimbursement environment, Sino Biopharm and Chia Tai Tianqing still see enormous opportunities within the industry. As the Chinese government places greater emphasis on innovation, the market space for novel drugs will continue to expand. However, only those products that truly possess market value will be able to better meet clinical needs under higher standards and promote the sustainable development of the industry.