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On September 30, Genentech, a division of Roche, entered into a major agreement with Rueger, with Genentech successfully acquiring Rueger's portfolio of next-generation CDK inhibitors for $850 million in upfront cash and other potential milestone payments. This transaction not only refreshes the down payment record for the foreign authorization of domestic molecules, but also marks a new milestone in the cooperation between the two sides. The previous record was held by Benefi Tianheng's agreement with BMS for the BL-B01D1 molecule, which was valued at $800 million. It is worth noting that the transaction between Benefi Tianhengand BMS only involves a single molecule BL-B01D1, which is already in the late clinical stage, and both parties share the subsequent overseas clinical costs. The collaboration with Genentech builds on a broader portfolio of next-generation CDK inhibitors, which is expected to include the Phase I CDK2/4/6 inhibitor RGT-419B and the preclinical CDK2 inhibitor QR-6401. Under the terms of the agreement, Genentech will be responsible for the global clinical development, manufacturing and commercialization of these products after the end of the existing Phase 1 clinical phase. Recently, the field of CDK inhibitors has become a hot spot pursued by many companies. In addition to Genentech, Beigene also announced the introduction of ETX-197, a CDK2 inhibitor from Onsun Pharma, at the end of November last year. Although the amount of the upfront payment was not disclosed, taking into account potential future milestone payments and sales sharing, the total value of the deal is up to $1.33 billion. With some generic CDK4/6 inhibitors entering the market in bulk, some investors are questioning whether the competitive landscape on the CDK inhibitor circuit has reached saturation. However, leading companies such as Roche and Beigene are still actively developing next-generation CDK inhibitors, which has a profound scientific and commercial logic behind it. CDKs (cyclin-dependent kinases), as an important member of the serine/threonine protein kinase family, play a crucial role in cell cycle regulation. CDK family targets are mainly divided into two categories: one is involved in cell cycle regulation and related mitosis, such as CDK1, 2, 4, 6; The other group is mainly involved in transcriptional regulation and phosphorylation of RNA polymerase II, such as CDK7, 8, 9, 11. Among them, CDK4/6 and CDK2 have attracted much attention due to their important roles in the development of tumors. CDK4/6 is a key condition protein in the human cell division and proliferation cycle, which can trigger the cell cycle transition from the growth phase (G1 phase) to the DNA replication phase (S phase). In many cancer cells, CDK4/6 is overexpressed, which promotes the disorderly proliferation of cancer cells through over-phosphorylation and inhibition of Rb protein. Therefore, CDK4/6 inhibitors can inhibit the proliferation of tumor cells by blocking the cell growth cycle in the G1 phase. CDK2 plays a key role in the early phase of DNA synthesis (G1 phase) and the phase of DNA synthesis (S phase) of the cell cycle, and its overexpression is closely related to the abnormal regulation of the cell cycle and the excessive proliferation of cancer cells. From a market perspective, breast cancer, as the world's largest malignant tumor (accounting for about 24.5% of all malignant tumors), provides a broad application space for CDK inhibitors. In particular, the large population of HR+/HER2- advanced breast cancer patients (about 60%-70%) makes endocrine therapy combined with CDK4/6 inhibitors a first-line treatment in this area. This also explains why CDK4/6 inhibitors can occupy an important position in the treatment of breast cancer and create a large drug market size. Despite the proliferation of blockbuster drugs in recent years, existing and older CDK4/6 inhibitors inevitably have several shortcomings, the most significant of which are drug toxicity and resistance. First, in terms of toxicity, hematotoxicity is the most common side effect of CDK4/6 inhibitors. These inhibitors inhibit cell proliferation by blocking the cell cycle, thus killing rapidly dividing cells, but this mechanism also leads to myelosuppression, which reduces blood cell production. Specifically, neutropenia, leukopenia, anemia, and thrombocytopenia are the most common hematological toxic side effects of commercialized CDK4/6 inhibitors. In addition, CDK4/6 inhibitors may also cause gastrointestinal adverse reactions, which should not be ignored. Second, in terms of drug resistance, although CDK4/6 inhibitors have achieved remarkable results in improving disease control in HR+/ HER2-breast cancer patients, 15-20% of patients still develop primary resistance to the drug at the beginning of treatment, while 30-40% of patients develop resistance gradually over the course of treatment. The mechanisms of drug resistance are complex and diverse, including but not limited to ESR1 gene mutation, upregulation of PI3K/AKT/mTOR signaling pathway, and BRCA2 gene mutation. In view of the influx of generic drugs of the older generation of CDK4/6 inhibitors and the urgent need to solve the existing toxicity and drug resistance problems, the new generation of CDK inhibitors ushered in more development opportunities. The RRT-419B that Roche is concerned about is a new generation of CDK2/4/6 small molecule inhibitor developed by Rueger Pharmaceutical. The drug is not commercially available worldwide, and its kinase activity profile has been optimized to target "better" safety and resistance CDK inhibitors from the outset. Regal's RRT-419B shows unique ingenuity in both design ideas and drug mechanisms, and has achieved preliminary validation of ideas in existing breast cancer clinical data. Unlike existing commercialized CDK inhibitors, which mainly inhibit subtypes 4 and 6, RGT-419B aims to reduce the occurrence of resistance to existing CDK4/6 inhibitors by increasing the inhibition of CDK2 subtypes, thereby achieving long-term efficacy. When CDK4/6 activity is inhibited, expansion of Cyclin E and activation of the oncogene MYC lead to up-regulation of MYC and activation of CDK2. CDK2-CyclinE, as a compensatory pathway, phosphorylates Rb, thereby releasing E2F transcription factors and promoting tumor cell proliferation. This process is the key to the development of acquired resistance to CDK4/6 inhibitors. Preliminary data from overseas studies such as Pfizer's CDK2 inhibitor PF-07104091 also revealed an association between CDK2 activation and acquired resistance to CDK4/6 inhibitors. In December 2023, Rueger presented the latest clinical data for RGT-419B at the SABCS Conference. The drug performed well in a Phase 1a clinical trial of monotherapy in 12 patients with HR+/ HER2-metastatic breast cancer receiving CDK4/6is and ET progression: three patients achieved partial response (PR) and continued treatment; Six patients received RGT-419B for more than 24 weeks; The drug was safe and well tolerated, no dose-limiting toxicity occurred, and no patient stopped treatment due to adverse events. Given the huge potential of next-generation CDK inhibitors in second-line breast cancer monotherapy, and the successful performance of commonly used second-line endocrine drugs such as fluvestrant in the market (such as the peak sales of $1.028 billion for fluvestrant in 2018), the global market for next-generation CDK inhibitors is expected to reach at least $2-3 billion. That is one of the reasons Roche is willing to bet so heavily. Faced with such a broad market prospect, many domestic pharmaceutical companies have also devoted themselves to the research and development of a new generation of CDK2/4/6 inhibitors or CDK2 inhibitors. One kind of large pharmaceutical companies further expand the development of CDK2 inhibitors on the basis of CDK4/6 inhibitor layout, such as Hengrui Pharmaceutical and First Sound Pharmaceutical; The other category is the first to enter the CDK inhibitor track of Biotech or big pharmaceutical companies such as Ruge Pharmaceutical, Stone pharmaceutical Group and Homology Kang Pharmaceutical. These companies are advancing the CDK inhibitor field and competing for future market share through continuous research and development and innovation. Although most of the CDK2/4/6 inhibitors that have entered the clinical stage in China are still in the early clinical stage, and most of them have not yet been validated by clinical data, it can be observed from the transaction cases of Regal Medicine and Beigene that these two authorized molecules have been deeply optimized by AI technology. From the information that has been made public, the AI pharmaceutical platform has played a key driving role in Genentech/Regal Pharma's RGT-419B and Beigene/Angsen Pharma's ETX-197 project. It is worth noting that the high degree of similarity among CDK family members makes the development of highly selective CDK2 inhibitors a great challenge. If the molecular selectivity is insufficient, it may lead to off-target phenomenon, which will affect the efficacy and safety of the drug. With the assistance of the AI model Kinetic EnsemNET, Onson has successfully identified a key hidden dynamic binding pocket of CDK2, thereby developing a potential BIC CDK2 candidate with high activity, high selectivity and a wide therapeutic window, which lays the foundation for its subsequent collaboration with Beigene. On the other hand, Ruge Pharmaceutical relied on its self-developed AI-assisted new drug research and development platform CARD to achieve the best selective screening of multiple CDK targets, and successfully promoted the clinical trial process of RGT-419B in the United States. From the licensing trend of CDK inhibitors, we can take a lesson: in the future, investors may need to pay more attention to the investment opportunities of Biotech companies that use AI technology to solve the difficult drug target or hot target iterative drug development challenges.

国产创新药出海的记录不断被刷新。 最新的记录创造者是锐格医药。近日，锐格医药宣布已与罗氏集团旗下的基因泰克就下一代CDK抑制剂达成收购协议。 根据协议条款，锐格医药将获得8.5亿美元的预付款，并有资格根据特定的开发、监管和商业里程碑的实现获得额外的现金付款。 这笔交易也刷新了国产创新药出海的预付款记录。之前的记录，由百利天恒的EGFR×HER3双抗ADC BL-B01D1对百时美施贵宝的授权交易保持（8亿美元）。 记录的不断刷新，不仅证明了国产创新药的质量，而且从产业角度来看，也反映了一个趋势： 经过十余年的缠斗，下一代CDK抑制剂的研发正在迈入一个新的高度。 卡位下一代CDK抑制剂 自从发现细胞周期蛋白依赖性激酶（CDK）以来，科学家们一直试图以它们为靶点来破坏癌细胞的分裂和增殖。 乳腺癌尤其依赖于这个过程来生长。也正因此，靶向CDK4和CDK6的第一代CDK抑制剂，大获成功。 2015年2月，由辉瑞研发的首款CDK4/6抑制剂哌柏西利在美国获批上市，用于治疗HR+/HER2-的局部晚期或转移性乳腺癌。 乳腺癌患者众多，2020年全球新增乳腺癌患者超230万人，成为全球第一大癌种。基于庞大的患者规模，哌柏西利的销售规模也颇为可观。 2016年，哌柏西利上市首个完整年度的销售额就已经达到21.35亿美元，成为一款当之无愧的重磅炸弹药物。此后，礼来、诺华、勃林殷格翰、恒瑞医药的CDK4/6抑制剂陆续获批上市。 2023年，仅辉瑞、诺华、礼来三家CDK4/6抑制剂，销售总额就接近100亿美元。基于CDK4/6抑制剂在乳腺癌领域的成功商业表现，Nature Reviews Drug Discovery预计，到2029年，CDK4/6抑制剂预计将贡献200亿美元，占乳腺癌药物销售市场份额的42%。 不过，已经上市的CDK4/6抑制剂并非完美，它们都或多或少有一些缺点。首先，困扰CDK4/6抑制剂的一个问题就在于毒性问题。目前，CDK4/6抑制剂最常见的不良反应是中性粒细胞减少，哌柏西利和瑞波西利出现比例最高，3-4级中性粒细胞减少的比例为60%-66%。 此外，骨髓抑制也是CDK4/6抑制剂最常见的毒性反应，在服用哌柏西利或瑞波西利的女性中出现率高达80%，在服用阿贝西利时出现率则高达50%。 这些不良反应限制了CDK4/6的给药剂量，在一定程度上影响了CDK4/6抑制剂的临床应用。也正因此，下一代CDK抑制剂的研发如火如荼。 备受关注的CDK2 CDK抑制剂的潜力不仅限于靶向CDK4和CDK6。 CDK家族成员众多，目前已发现有20个不同的亚型，根据其功能可分为两类：一类CDK参与细胞周期调控，如CDK1、CDK2、CDK4、CDK6等；另一类CDK参与转录调节，主要包括CDK7、CDK8、CDK9、CDK10、CDK11等。 其中，许多家族成员都是有潜力的药物靶点，CDK2是目前研究的热点之一。 与罗氏达成重要合作的锐格医药，其产品线中有两个在研的CDK抑制剂，均以CDK2为靶点：一款是CDK2/4/6抑制剂RGT-419B，另一款是CDK2抑制剂QR-6401。 同样，去年11月21日，百济神州与昂胜医药合作，获得了后者在研口服CDK2抑制剂ETX-197的全球独家权益。 CDK2受到关注并不意外，关键在于其巨大的潜力。 例如，CDK2可能有助于解决CDK4/6抑制剂的耐药问题。CDK4/6抑制剂作为一线治疗，无论是联合芳香化酶抑制剂还是氟维司群，都有15%-20%的患者会出现原发性耐药，而且在CDK4/6抑制剂使用后期几乎都会发展出继发性耐药。一旦产生耐药，患者的治疗选择将非常有限。 看来，CDK2是一个潜在的突破口。研究表明，在CDK4被抑制后，CDK2会接管其作用并促进癌细胞增殖。这些癌细胞不仅会继续生长，还可能对之前的CDK抑制剂治疗产生耐药。这表明CDK2可能是CDK4/6耐药机制之一。 这一点也得到了辉瑞的初步验证。在临床试验中，16名接受过2线CDK4/6i+内分泌单药治疗的转移性乳腺癌患者，在经过辉瑞研发的CDK2选择性抑制剂PF-07104091治疗后，有3名患者达到部分缓解，6名患者达到疾病稳定。初步结果显示，PF-07104091对CDK4/6抑制剂耐药的HR+/HER2-乳腺癌患者具有良好的疗效。 这意味着，CDK2与CDK4/6联合使用，可能有助于解决耐药问题。 锐格医药进展较快的RGT-419B，其研发目标也是解决对CDK4/6和其他激素受体调节疗法的耐药性问题。临床前数据显示，在对目前批准的CDK4/6抑制剂耐药的ER+乳腺癌细胞中，RGT-419B显示出对癌细胞增殖的完全抑制。在这些实验中，RGT-419B与选择性雌激素受体降解剂或PI3K信号通路抑制剂联合使用时，其对肿瘤细胞的抑制作用进一步增强。 站队进行时 面对CDK抑制剂百亿美金市场的巨大诱惑，已经有不少国内外药企开始跃跃欲试。 目前，针对CDK2以及CDK4/6的药企布局已经相当广泛。在国内，辰欣药业、石药集团、齐鲁制药、同源康医药等都在进行CDK2/4/6抑制剂的临床试验。 在海外，辉瑞的研发进展最快，在去年的ASCO大会上，辉瑞已经公布了其候选药物PF-07104091的1/2a期临床数据，并且正在进行为期三年的研究。此外，Incyte的INCB123667、Blueprint的BLU-222等CDK2抑制剂也都处于临床研究阶段。 现在，随着罗氏的加入，围绕新一代CDK抑制剂的竞争无疑将更加激烈。对于生物技术公司来说，在研发更优秀的分子的同时，可能还需要考虑关于战略选择的问题。 毕竟，大型药企的加入会时刻改变竞争格局。一方面，像罗氏这样的巨头引进项目的核心，本质上是利用其“临床开发实力、制造能力和商业影响力”来创造更多价值的交易。在这三个方面，biotech并不占优势。 另一方面，一些大型药企在乳腺癌领域已经形成了生态突破的能力。最典型的例子就是罗氏，从HER2到PI3K靶点，罗氏引领了乳腺癌领域靶向药物的研发热潮，并且至今仍在推动这一领域向更高层次发展。换句话说，这些大型药企在这些特定领域的竞争力将进一步得到加强。 对于biotech而言，需要做得更快，也需要确保商业化预期的实现，在这种背景下，战略选择可能是最关键的。 那么，在这一领域，国内biotech是否还会创造新的BD记录呢？ 来源 | 氨基观察（药智网获取授权转载） 撰稿 | 郑晓 责任编辑 | 八角 声明：本文系药智网转载内容，图片、文字版权归原作者所有，转载目的在于传递更多信息，并不代表本平台观点。如涉及作品内容、版权和其它问题，请在本平台留言，我们将在第一时间删除。 商务合作 | 王存星 19922864877（同微信）  阅读原文，是受欢迎的文章哦