Thyroid Cancer, Medullary

近期，中国科学院上海药物研究所徐石林团队和暨南大学药学院张章副研究员合作，开发了一类RET PROTAC降解剂，对RET溶剂前沿突变耐药有效，细胞活性显著优于抑制剂；相关工作以“Discovery of an Efficacious RET PROTAC Degrader with Enhanced Antiproliferative Activity Against Resistant Cancer Cells Harboring RET Solvent-front Mutations”为题发表在药物化学TOP期刊Journal of Medicinal Chemistry上。  RET是一种跨膜受体酪氨酸激酶，其信号传导通过胶质细胞系来源的神经营养因子（GDNF）家族配体与其受体结合来介导。RET的基因融合和突变与多种癌症密切相关，例如在60%的甲状腺髓样癌、10%-20%的甲状腺乳头状癌以及1%-2%的非小细胞肺癌中均有发现。因此，RET被视为人类癌症治疗的潜在靶点。 过去几十年中，研究人员开发了多种RET小分子抑制剂。第一代多靶点激酶抑制剂（如Vandetanib和Cabozantinib）因脱靶相关的毒副作用以及守门员突变（V804M/L）引发的耐药性而在临床应用中受到限制。第二代RET抑制剂Selpercatinib和Pralsetinib，通过提高选择性并增强对V804M/L突变的抑制活性，显著提升了安全性和有效性，现已获FDA批准用于治疗非小细胞肺癌和甲状腺癌。然而，这些选择性RET抑制剂对溶剂前沿G810突变导致的耐药性仍然束手无策，推动了第三代RET抑制剂的研发。因此，作者探索了一种新的替代策略，旨在克服溶剂前沿突变引起的选择性RET抑制剂耐药问题。 作者以第二代选择性RET抑制剂Selpercatinib为基础，设计并合成了一系列RET PROTAC降解剂。通过分析Selpercatinib与RET激酶域的共晶结构（PDB ID: 7JU6），发现其吡唑并[1,5-a]吡啶母核6位的2-羟基-2-甲基丙氧基暴露于溶剂区域。结合已有的构效关系数据，作者将该基团替换为吡唑基团，并将其作为连接手柄（图1）。随后，作者对连接链进行优化，最终筛选出具有强效降解活性和抗细胞增殖活性的RET PROTAC降解剂20（QZ2135）。  图1：针对RET的PROTAC降解剂的设计 作者首先对化合物20的降解活性进行了表征，结果显示其能够在Ba/F3-KIF5B-RET细胞中高效降解RET蛋白（DC50 = 4.7 nM，Dmax = 83%）（图2）。随后，在表达RET融合蛋白的人类肺腺癌细胞系LC-2/ad中评估其降解活性，结果表明化合物20同样能够有效诱导RET蛋白降解（图3）。此外，作者还对化合物20进行了蛋白降解动力学研究、RET蛋白稳定性分析以及洗脱实验，这些结果进一步证实化合物20是一种高效且作用快速的RET PROTAC降解剂。  图2：化合物20的降解活性表征  图3：化合物20在LC-2/ad细胞中对RET蛋白水平的影响 作者进一步验证了化合物20的降解机制。通过Selpercatinib、MLN4924、MG132、Lenalidomide和阴性对照物26等竞争性实验，表明其通过泛素-蛋白酶体系统介导RET蛋白的降解（图4）。  图4：化合物20的降解作用机制 作者评估了化合物20在携带RET耐药突变的Ba/F3细胞中的降解活性（图5）。结果显示，化合物20不仅对RET V804M突变具有较高的降解活性（DC50 = 17.2 nM），还能够有效降解溶剂前沿突变RET G810C（DC50 = 73.8 nM）。  图5：化合物20在携带耐药突变的Ba/F3细胞中介导的RET降解 在细胞增殖抑制实验中（图6），化合物20在携带溶剂前沿突变的Ba/F3-KIF5B-RET-G810C/R/S细胞中表现出有效的抗增殖活性，其IC50值分别为0.05μM、0.15μM和0.09μM，相较于Selpercatinib分别提升约14倍、7倍和6.3倍。此外，化合物20在这些突变细胞系中的抑制活性也明显优于其阴性对照化合物26。这一结果表明，化合物20作为PROTAC降解剂的作用机制，可能是其抗增殖活性优于传统RET抑制剂的关键原因。  图6：化合物对携带不同RET融合蛋白和耐药突变的Ba/F3细胞的抗增殖活性 此外，在细胞水平上，化合物20相比于Selpercatinib，对携带溶剂前沿突变G810C/R的RET磷酸化表现出更强的抑制活性（图7）。此外，化合物20还能够以剂量依赖的方式诱导Ba/F3-KIF5B-RET-G810C细胞发生凋亡（图8）。  图7：化合物20在携带KIF5B-RET融合蛋白和耐药突变的Ba/F3细胞中对RET磷酸化及下游信号传导的抑制作用  图8：化合物20在Ba/F3细胞中诱导的凋亡 鉴于化合物20在体外的优异表现，作者进一步评估了其在体内的抗肿瘤疗效。利用Ba/F3-KIF5B-RET-G810C异种移植小鼠模型，作者每天对小鼠腹腔注射化合物20（10 mg/kg或30 mg/kg）。14天后，化合物20有效抑制了肿瘤生长，其中在30 mg/kg剂量下的肿瘤生长抑制率为49.2%。在整个治疗过程中，与对照组相比，小鼠未出现显著的体重变化（图9）。此外，作者进一步检测了连续三天腹腔注射化合物20后，小鼠肿瘤组织中RET蛋白的水平。结果显示，化合物20在10 mg/kg和30 mg/kg剂量下分别诱导了47.0%和55.3%的RET蛋白降解。这些结果充分证明了化合物20的体内有效性和良好的安全性。  图9：化合物 20 在 Ba/F3-KIF5B-G810C 细胞异种移植小鼠模型中的体内抗肿瘤疗效。 本研究利用PROTAC靶向蛋白降解技术，成功设计并鉴定出一种高效的RET PROTAC降解剂——化合物20，为克服由溶剂前沿突变引发的RET抑制剂耐药性提供了一种替代策略。 本论文通讯作者为中国科学院上海药物研究所徐石林研究员和暨南大学张章副研究员，共同第一作者分别为南京中医药大学硕士生张倩、暨南大学硕士生何颖祺和中国科学院上海药物研究所博士生饶丹妮。 声明：发表/转载本文仅仅是出于传播信息的需要，并不意味着代表本公众号观点或证实其内容的真实性。据此内容作出的任何判断，后果自负。若有侵权，告知必删！ 长按关注本公众号  粉丝群/投稿/授权/广告等 请联系公众号助手 觉得本文好看，请点这里↓

THURSDAY, Dec. 26, (2024 HealthDay News) -- The U.S. Food and Drug Administration (FDA) announced on Monday the approval of the first generic version of a daily injectable GLP-1 medicine for people living with Type 2 diabetes. Liraglutide , the generic for Victoza, is similar to semaglutide, the active ingredient in the popular weight-loss drug Ozempic . The FDA supports the development of generic drugs, such as GLP-1s, by funding research and informing industry through guidance, Dr. Iilun Murphy , director of the FDA’s Office of Generic Drugs, said. “Generic drugs provide additional treatment options which are generally more affordable for patients,” she said in a statement released Dec. 23, 2024. “Today’s approval underscores the FDA’s continued commitment to advancing patient access to safe, effective and high-quality generic drug products.” Last month, the agency approved the first generic version in this class of medications with the green lighting of a generic version of Byetta (exenatide) . Experts hope the new approvals will help prevent shortages triggered by demand for injectable weight loss and type 2 diabetes drugs, including semaglutide (Ozempic, Wegovy ) and tirzepatide ( Mounjaro , Zepbound ). Liraglutide is expected to expand access for people managing type 2 diabetes , which affects more than 38 million Americans, according to federal health data. Type 2 diabetes is a chronic condition that occurs when the body does not use insulin well and cannot keep blood sugar at normal levels. It is usually diagnosed in adults, but has been increasingly diagnosed in children and teens. Liraglutide improves blood sugar levels by creating similar effects in the body as GLP-1 in the pancreas, which is often found in insufficient levels in those with type 2 diabetes. The prescribing information for the generic version includes a warning about the increased risk of thyroid C-cell tumors. For this reason, patients who have had, or have family members who have ever had medullary thyroid carcinoma should not use liraglutide, nor should those who have an endocrine system condition called multiple endocrine neoplasia syndrome type 2. The most common side effects reported in the clinical trials for liraglutide injection include nausea, diarrhea, vomiting, decreased appetite, dyspepsia and constipation. Whatever your topic of interest, subscribe to our newsletters to get the best of Drugs.com in your inbox.

THURSDAY, Dec. 26, (2024 HealthDay News) -- The U.S. Food and Drug Administration (FDA) announced on Monday the approval of the first generic version of a daily injectable GLP-1 medicine for people living with Type 2 diabetes . Liraglutide , the generic for Victoza , is similar to semaglutide, the active ingredient in the popular weight-loss drug Ozempic . The FDA supports the development of generic drugs, such as GLP-1s, by funding research and informing industry through guidance, Dr. Iilun Murphy , director of the FDA’s Office of Generic Drugs, said. “Generic drugs provide additional treatment options which are generally more affordable for patients,” she said in a statement released Dec. 23, 2024. “Today’s approval underscores the FDA’s continued commitment to advancing patient access to safe, effective and high-quality generic drug products.” Last month, the agency approved the first generic version in this class of medications with the green lighting of a generic version of Byetta (exenatide) . Experts hope the new approvals will help prevent shortages triggered by demand for injectable weight loss and type 2 diabetes drugs, including semaglutide (Ozempic, Wegovy ) and tirzepatide ( Mounjaro , Zepbound ). Liraglutide is expected to expand access for people managing type 2 diabetes , which affects more than 38 million Americans, according to federal health data. Type 2 diabetes is a chronic condition that occurs when the body does not use insulin well and cannot keep blood sugar at normal levels. It is usually diagnosed in adults, but has been increasingly diagnosed in children and teens. Liraglutide improves blood sugar levels by creating similar effects in the body as GLP-1 in the pancreas, which is often found in insufficient levels in those with type 2 diabetes. The prescribing information for the generic version includes a warning about the increased risk of thyroid C-cell tumors. For this reason, patients who have had, or have family members who have ever had medullary thyroid carcinoma should not use liraglutide, nor should those who have an endocrine system condition called multiple endocrine neoplasia syndrome type 2. The most common side effects reported in the clinical trials for liraglutide injection include nausea, diarrhea, vomiting, decreased appetite, dyspepsia and constipation. Whatever your topic of interest, subscribe to our newsletters to get the best of Drugs.com in your inbox.