Gliosarcoma

迄今为止，超过260款ADC已在临床中针对各种肿瘤适应症进行研究，其中92款已终止(图1)[1]，主要归因于以下三个原因中的一种或多种：1)由于无法耐受的毒性而导致治疗效果不足。2)由于疗效不足而导致治疗效果与当前护理标准相比无优势。3)商业考量/发展决策。 图1. 已终止临床研究的ADC简要概况(按Payload及临床进展分类)“ADC终止”系列将对已终止研究的ADC相关局限性进行分析，助力后续该系列药物的的设计与开发。本期我们将讨论Glembatumumab Vedotin (2006→2018；CDX-011, CR011vcMMAE；Celldex Therapeutics公司)、Depatuxizumab Mafodotin (2013→2019；ABT-414, Depatux-M；Abbvie公司)的相关数据及终止开发原因。01 Glembatumumab Vedotin (CDX-011, CR011vcMMAE)Glembatumumab Vedotin (CDX-011, CR011vcMMAE)由Celldex Therapeutics公司研发，管线生存期为2006-2018年。CDX-011主要用于治疗表达糖蛋白非转移性黑色素瘤蛋白B (GPNMB)的癌症。Glembatumumab是一种完全人源化IgG2单克隆抗体(CR011)，通过HEK293细胞纯化得到的GPNMB胞外域结构(ECD)作为免疫原，利用XenoMouse技术[2]生成全人抗GPNMB mAb，其对纯化的GPNMB-ECD蛋白表现出52 nmol/L的Kd值[3]。实验表明，CR011单独给药并不能抑制表达GPNMB的黑色素瘤细胞系的生长，但与含有毒素(Saporin，皂草素)的二抗结合时，细胞的生长能够得到有效且特异性的抑制。受上述实验结果的影响，为了能够产生适合癌症治疗的药物，后续采用非特异性偶联(TCEP还原链间二硫键)的方法，将Glembatumumab通过组织蛋白酶B可裂解的缬氨酸-瓜氨酸(Val-Cit)二肽Linker与高效的微管抑制剂MMAE偶联缀合，平均DAR约为2.7[3, 4]。通过流式细胞术检测发现，偶联后仍与表达GPNMB的SK-Mel-2黑色素瘤细胞保持良好的结合活性(图2A)。为了评估CDX-011是否特异性抑制表达GPNMB的黑色素瘤细胞的生长，通过克隆形成测定以评估CDX-011处理后的细胞活力。实验结果表明，CDX-011能够抑制GPNMB+的SKMel-2和SK-Mel-5黑色素瘤细胞系的生长(IC50分别为216和300 ng/mL，图2A)，但不抑制GPNMB-的LOXIMVI和TK-10细胞系生长(IC50均>1000 ng/mL，图2A)。相比之下，当使用浓度高达1000 ng/mL时，MMAE偶联同种型对照抗体(IgG2-vcMMAE)不会抑制GPNMB+/-细胞系的生长。由于所有测试的细胞系对游离MMAE的敏感性大致相同(图2A)，因此这些结果表明GPNMB+细胞对CDX-011敏感性的增加并不是由于这些细胞对MMAE生长抑制作用的敏感性固有增加。通过竞争实验进一步说明了CDX-011介导的生长抑制特异性，其中发现裸抗CR011能够降低CDX-011对SKMel-2细胞系的生长抑制水平。 图2. CDX-011的体内外抗肿瘤活性体内实验表明，在人黑色素瘤异种移植小鼠中静脉注射CDX-011评估其抗肿瘤活性，在用PBS处理的对照组中观察到持续性的肿瘤生长，在用CDX-011处理的小鼠中肿瘤体积以剂量依赖性的方式受到抑制(图2B)。在最低浓度CDX-011 (0.313 mg/kg)处理下肿瘤生长抑制是显著的，并且在用≥1.25 mg/kg浓度的CDX-011治疗后大多数动物中观察到肿瘤完全消退，大多数在CDX-011治疗后消退的肿瘤在200天的治疗后观察期内没有再生[3, 5]。与游离的MMAE和裸抗CR011的治疗相比，相同剂量(5.0 mg/kg)下仅有CDX-011展现抗肿瘤活性并使肿瘤完全消退，另外两者均不能抑制肿瘤生长(图2C)。在对另一种GPNMB+人类黑色素瘤细胞系(SK-Mel-5)异种移植物的小鼠给药CDX-011时，也能发现肿瘤消退。在异种移植实验中没有观察到接受治疗的动物中毒死亡，也没有出现异常行为或其他非特异性药物毒性迹象。此外，每周两次的体重测量并未显示由于给药CDX-011而导致的体重减轻。为了更进一步地探究CDX-011的药理学特性[6]，采用q4d×4的给药方式处理人SK-MEL-2和SK-MEL-5异种移植模型(PDX)，CDX-011以剂量依赖性方式产生显著的抗肿瘤作用并引起肿瘤消退，值得注意的是消退的肿瘤在观察期间(200天)没有重新生长；此外，CDX-011抗肿瘤活性优于化疗药物Vinblastine和Paclitaxel (均为最大耐受剂量，图3A)。服药后30天以上可在血清中检测到CDX-011≥1 μg/mL (∼0.01 μM，图3B)；CDX-011的消除半衰期为10.3天；低分布体积表明CDX-011仅限于血液和组织液中。CDX-011可以通过单次推注剂量或间歇给药(即每1、2、4、8或16天)的方式给药，无肿瘤幸存者的比例没有明显差异，表明缺乏时间依赖性。此外，血浆IL-8可能作为治疗反应的替代指标，经CDX-011处理后血浆中肿瘤来源的人IL-8的减少与肿瘤结节的消失同时发生(图3C)。 图3. CDX-011药理学性质研究虽然上述提供的数据可与临床应用相关，但应注意的是CR011不结合正常小鼠组织中表达的小鼠GPNMB蛋白，因此体内治疗研究可能会低估毒性和ADC在临床环境中的交叉反应[3, 6]。但总体而言，CDX-011的药理学特性表明该药物可能在控制人类黑色素瘤方面具有临床实用价值。CDX-011于2006年6月22日进行Ⅰ期临床试验，2008年四月份开始Ⅱ期临床试验，2010年五月在美国获得快速审查资格(Fast Track Designation)用于治疗表达GPNMB的晚期、难治性或耐药性乳腺癌，2014年第一季度开展Ⅲ期临床试验，2018年4月18日Celldex宣布不再继续CDX-011的临床试验，主要原因是该临床试验的结果表明CDX-011与Xeloda® (capecitabine)相比对转移性三阴性乳腺癌(GPNMB高表达)的疗效并未到达主要终点[7]。这期间开展了多项临床试验(表1)，其临床试验结果多不尽人意[8-13]。表1. CDX-011涉及的临床试验临床试验中Gr≥3 AEs较为常见，严重皮疹是CDX-011的剂量限制毒性之一，这可能是与靶点GPNMB在皮肤中表达相关，此外中性粒细胞减少症、神经病变、瘙痒、脱发等毒性也不容小觑，这些现象背后的机制尚不清楚，可能与健康细胞中GPNMB表达有关。在CDX-011中期临床试验失败后，Celldex宣布裁员20%。除CDX-011开发计划终止后，该公司宣布还将取消正在进行的CDX-014开发[14]。该款ADC以TIM-1为靶点，目前正处于肾细胞癌和透明细胞卵巢癌的早期I期开发阶段。02 Depatuxizumab Mafodotin (ABT-414, Depatux-M)Depatuxizumab Mafodotin (ABT-414)由Abbvie公司研发，管线生存期为2013-2019年。ABT-414靶向表皮生长因子受体(EGFR)，其主要适应症为星形胶质瘤。ABT-414主要由ABT-806和MMAF通过不可裂解Linker (Maleimido Caproyl, MC)偶联组成，其偶联方式为非特异性链间Cys偶联，DAR~3.8[15]。ABT-806是单体mAb806的人源化形式，可结合EGFR CR1结构域中的隐匿表位，该表位在表达扩增和过表达的野生型EGFR或缺失突变型EGFR变体III的肿瘤中多见[16]。ABT-806的正常组织结合率较低，已在I期试验中得到证实，其中ABT-806在最高测试剂量(24 mg/kg)下具有良好的耐受性，并且没有出现特征性EGFR抑制剂涉及的皮肤病不良事件[17]。此外，ABT-806具有较长的半衰期，并呈现剂量依赖性的药代动力学特征。因此，ABT-806是一种极具吸引力的候选药物，可用作ADC的构建，向表达野生型或突变型EGFR的肿瘤细胞递送有效的细胞毒性载荷，从而降低对正常组织的细胞毒性。ABT-806与MMAF偶联后构建的ABT-414并不会改变亲本抗体的结合特性，同时以相似的活性抑制EGFR介导的信号传导(图4A)。针对表达不同形式和数量的EGFR的人类肿瘤细胞系，ABT-414对过表达野生型或突变型EGFR的肿瘤细胞系表现出显著的细胞毒性，IC50可达纳摩尔浓度水平，且杀伤作用呈现靶标依赖性，与EGFR数量呈现良好的相关性(图4B)。 图4. ABT414结合活性及细胞毒性研究ABT-414的体内活性在11个异种移植模型中进行验证，经ABT-414给药处理，其中9个异种移植模型中的肿瘤生长得到延迟或抑制(图5A)，且在所有模型中，ABT-414的抗肿瘤活性均显着高于亲本ABT-806。对ABT-414治疗敏感的肿瘤模型可观察到肿瘤消退，特别是在A431异种移植鳞状肿瘤模型中ABT-414可介导肿瘤消退并治愈(图5B)；此外，ABT-414对NCI-H1703 (肺鳞状细胞癌)、HCC827.ER.LMC (具有EGFR激活突变的肺腺癌)和SCC-15 (头颈鳞状细胞癌)异种移植模型也非常有效(图5C-E)。当然，并非所有表达EGFR的异种移植模型都容易受到ABT-414给药的抑制，其中EGFR表达水平较低的HCT-15和A549异种移植模型对ABT-414治疗没有反应。 图5. ABT-414在野生型和突变型EGFR表达模型中的体内活性基于前期ABT-806的体内实验设计，在扩增表达外源EGFRvIII的U87MGde2-7多形性胶质母细胞瘤(GBS)模型中评估ABT-414的活性，ABT-414在4 mg/kg剂量下引起肿瘤完全消退并治愈(图6A)，相比之下，即使剂量为20 mg/kg ABT-806也不会引起肿瘤消退，仅能抑制肿瘤生长。在共表达扩增的EGFR野生型和EGFRvIII的GBS PDX模型SN0199和表达野生型EGFR的SN0207中评估ABT-414活性，在SNO199和SNO207模型中，ABT-414治疗均引起显着的肿瘤生长抑制(SN0207，87% TGImax；SN0199，96% TGImax)和消退(图6B)。此外，还在U87MGde2-7异种移植模型中评估ABT-414与GBS标准护理化疗和放疗相结合的肿瘤抑制活性。在替莫唑胺(1.5 mg)的临床组合中添加ABT-414 (1 mg/kg)和分段放射(2 Gy)导致显著的额肿瘤生长抑制和肿瘤生长延迟(图6C-E)。三重组合疗法显示出比当前护理标准更显著的抗肿瘤效果，说明该组合方案有增强疗效的潜力。 图6. ABT-414对GBS细胞系和PDX模型的疗效总之，ABT-414是一种具有独特靶向能力、有前途的治疗药物。临床前数据支持ABT-414在表达EGFR的恶性肿瘤中的持续临床评估。ABT-414在2012年十月进行I/II临床试验(NCT01741727)，用于肺鳞状细胞癌的治疗；分别于2014年7月27日和8月4日在欧盟和美国获得治疗GBS的孤儿药资格(Orphan Drug Designation)；于2016年7月11日在美国获得罕见儿科疾病认定(Rare Pediatric Disease Designation)，用于治疗弥漫性内源性脑桥胶质瘤。2019年5月17日，ABT-414在Ⅲb期临床试验(NCT03419403，UNITE)中联合放化疗给药用于GBS治疗，由于缺乏生存获益而终止研究。此外，同种联合给药疗法在治疗恶性胶质瘤/神经胶质肉瘤的Ⅱ/Ⅲ期临床试验(NCT02573324)中ABT-414与对照组相比无明显的总生存时间(OS)差异[18, 19]。此外，ABT-414还具有一定的眼毒性[20, 21]。ABT-414临床的失败是否与其适应症有关，毕竟GBS属于脑部肿瘤，ABT-414透过血脑屏障(BBB)的效率可能是影响疗效的重要因素。针对此问题，AbbVie采用ABT-806进行研究，注射(IV)后到达大脑的皮质层和深层皮质下结构，同时也验证了ABT-414，注射后可与EGFR+ GBM植入物结合[22]。但是，异种移植物的位置差异以及实际肿瘤的微环境是否会对ABT-414脑内暴露程度有影响并未进行更深一步的研究。免责声明：本文仅作信息交流之目的，文中观点不代表个人立场，亦不代表个人支持或反对文中观点。本文并非治疗方案推荐。如需获得治疗方案指导，请前往正规医院就诊。欲有所明，终有所蔽。欢迎各位批评指正(dyc21@mails.tsinghua.edu.cn)，谢谢！ 主要参考文献 1. Maecker, H., et al., Exploration of the antibody–drug conjugate clinical landscape. mAbs, 2023. 15(1): p. 2229101.2. Foltz, I.N., K. Gunasekaran, and C.T. King, Discovery and bio-optimization of human antibody therapeutics using the XenoMouse® transgenic mouse platform. Immunol Rev, 2016. 270(1): p. 51-64.3. Tse, K.F., et al., CR011, a fully human monoclonal antibody-auristatin E conjugate, for the treatment of melanoma. Clinical Cancer Research, 2006. 12(4): p. 1373-1382.4. Doronina, S.O., et al., Development of potent monoclonal antibody auristatin conjugates for cancer therapy. Nat Biotechnol, 2003. 21(7): p. 778-84.5. Naumovski, L. and J.R. Junutula, Glembatumumab vedotin, a conjugate of an anti-glycoprotein non-metastatic melanoma protein B mAb and monomethyl auristatin E for the treatment of melanoma and breast cancer. Curr Opin Mol Ther, 2010. 12(2): p. 248-57.6. Pollack, V.A., et al., Treatment parameters modulating regression of human melanoma xenografts by an antibody–drug conjugate (CR011-vcMMAE) targeting GPNMB. Cancer Chemotherapy and Pharmacology, 2007. 60(3): p. 423-435.7. https://ir.celldex.com/news-releases/news-release-details/celldexs-metric-study-metastatic-triple-negative-breast-cancer-0.8. Vaklavas, C. and A. 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Adam Zamecnik @a_zamecnik The UK has rejoined EU’s Horizon Europe science research programme. Image Credit: Shutterstock / vlastas The UK has re-joined the EU’s Horizon Europe science research programme after the country’s post-Brexit absence and long-stalled talks. British scientists will now be able to apply for grants and bids to take part in Horizon Europe projects, based on the UK Government’s 7 September announcement. Recommended Reports Reports LOA and PTSR Model - RRX-001 in Gliosarcoma GlobalData Reports State of the Biopharmaceutical Industry 2022 GlobalData View all As an EU member state at the time, the UK was part of the EU’s past Horizon 2020 research funding programme. This programme has since been succeeded by Horizon Europe, which uses its budget of €95.5bn to support research across the region. The programme not only offers funding for research but also provides a chance for collaboration across Europe and beyond such as Armenia, Israel, and New Zealand. “The UK’s decision to re-join the Horizon Europe funding programme will be welcomed warmly by researchers across the EU and Great Britain today,” said Dr Harshil Pate, head of scientific development at Seqera Labs after the announcement. “Tackling the many challenges facing humanity in the 21st century requires international collaboration that sees past borders, uniting our innovative research sectors to improve human health through cutting-edge discoveries in RNA vaccines, DNA analysis and more.” Whilst the UK was initially supposed to be a part of the programme as an associate, its membership was halted by disagreements with the EU over the future of trade rules in Northern Ireland. While a breakthrough in the Northern Ireland talks opened the possibility of readmission , the process faced further delays as reported by outlets at the time. However, the country has now re-joined the scheme and will be a fully associated member of the programme until it concludes in 2027, based on the 7 September announcement . The UK will start financially supporting the Horizon Europe scheme only in January 2024. Furthermore, the UK will also have a new automatic clawback that gives it compensation rights in case that British scientists receive less funding from the programme than what the country will invest. The European Commission estimates that the UK will pay almost €2.6bn per year for its participation in Horizon Europe and the Copernicus earth observation programme, which the country will also rejoin, based on a 7 September European Commission press release. However, the country will not rejoin the EU’s atomic Euratom programme. “We have worked with our EU partners to make sure that this is the right deal for the UK, unlocking unparalleled research opportunities, and also the right deal for British taxpayers,” said UK Prime Minister Rishi Sunak in the statement. The political agreement must now be approved by the European Council before being formally adopted in the EU-UK Specialised Committee on Participation in Union Programmes, per the European Commission’s statement.

Dasiglucagon is intended for usage in infants aged seven days and above with congenital hyperinsulinism. Credit: Liudmila Fadzeyeva / Shutterstock.com. The US Food and Drug Administration (FDA) has granted priority review for Zealand Pharma ’s dasiglucagon for hypoglycemia prevention and treatment in the paediatric population with congenital hyperinsulinism (CHI), a rare genetic ailment. Dasiglucagon is intended for usage in infants aged seven days and above, dosing for up to three weeks. Recommended Reports Reports LOA and PTSR Model - Aminolevulinic Acid Hydrochloride in Cervical Intraepithelial Neoplasia (CIN) GlobalData Reports LOA and PTSR Model - Pazopanib Hydrochloride in Gliosarcoma GlobalData View all Companies Intelligence Zealand Pharma AS CGM SpA View all A decision on the approval from the regulatory agency is anticipated on 30 December 2023. The regulator will carry out the review in two stages under one new drug application (NDA) to guarantee the best regulatory approach. Part one is linked to dosing with dasiglucagon for up to three weeks while part two is linked to the product’s usage beyond that time. To assess the usage of dasiglucagon for the disease beyond three weeks, the regulator sought further assessments from existing continuous glucose monitoring datasets. Zealand Pharma is expected to make the submission before the end of 2023. The Prescription Drug User Fee Act (PDUFA) date for the second part will be decided after filing data from further analyses of existing datasets sought by the FDA. The company chose CGM as a secondary outcome measure in Phase III clinical trials of dasiglucagon. Zealand Pharma chief medical officer David Kendall stated: “We believe that the decision of the FDA to provide such a fast review cycle for the first part of the NDA is a strong testament to the potential value of this product to patients. “We remain in close dialogue with the FDA and appreciate the collaborative nature of our work with the agency, recommending a review of the NDA in two parts under the same application to ensure patient access as fast as possible. “We look forward to continued dialogue with the FDA in generating additional analyses from existing datasets around the use of CGM to be submitted before the end of the year for part two of the NDA review.”