Metal Chelate Conjugated Monoclonal Antibodies for Tumor Diagnosis and Therapy

肿瘤相关单克隆抗体（mAbs）作为恶性肿瘤细胞毒性药物的选择性载体是一种治疗药物。这一假设在动物模型系统中进行了测试，其中单克隆抗体针对与人类疾病相关的抗原。所使用的细胞杀伤剂是粒子发射放射性核素。在适当验证的小鼠肿瘤异种移植模型系统中评估其相对疗效。所选择的放射性核素集中在适当的α和β发射体上。目前的研究继续集中在Pb-212上，这是一种与α发射器At-211平行的β -发射α粒子源。正在进行的临床前试验使用螯合剂1B4M-DTPA（又名MX-DTPA或tixetan）或CHX-A（双prime） DTPA。两者在临床应用中都很成熟；前者是泽瓦林的组成部分。化学使泽伐林，第一个FDA批准的放射性标记抗体治疗，可能是由化学部门开发的。几乎所有正在进行的研究现在都使用第三代双功能螯合剂CHX-A（双prime） DTPA来隔离In-111、Y-90、Bi-213和Lu-177。先前的研究证实了CHX-A（双撇）DTPA在PET成像中的使用，Y-86生产的（由化学部门精制和纯化的）旋转加速器通过化学部门最近报道的许多PET成像研究，关于Y-86用于PET成像靶向HER2和HER1(EGFR)，用于可视化各种疾病，如卵巢癌，结肠直肠癌，胰腺癌，前列腺癌。Y-86靶向HER1(EGFR) PET成像间皮瘤的相关研究已发表。与用于免疫pet的Y-86的开发相辅相成，化学部门继续开发用于Zr-89免疫pet的新型和优质双功能螯合剂。目前的技术是繁琐的，不稳定的体内导致骨沉积释放的Zr-89。通过这一研究项目开发的Zr-89配合物稳定性显著提高的先导化合物现已发表，双功能类似物的创造已经实现。对这些药物的评价已经开始。新型双功能螯合剂和靶向放疗连接剂的临床前评估继续完善偶联化学选择和放射性标记改进。这些改进源于提供用于肽化学的试剂以及适用于放射性镧系元素和α粒子发射放射性核素的位点特异性偶联策略。针对位点特异性连锁策略，如点击化学和碳水化合物修饰策略，已经创建了新的连锁化学试剂。临床前At-211研究已经启动，针对HER2的剂量递增生存研究使用连接试剂N-Me-SAPS将At-211与曲妥珠单抗连接起来。包括毒性评估在内的这些研究的重复将为扩展到长期治疗研究提供最佳剂量。at -211已被生产并提供给约翰霍普金斯大学的合作者，以努力建立at -211使用者/研究者联盟，以加速评估这种放射性核素的治疗潜力及其临床转化。对使用Pb-212治疗弥漫性腹腔内疾病（如卵巢癌或胰腺癌）的高度广泛和集中的临床前研究仍在继续。Pb-212的开发继续进入开放的I期临床试验，有14名患者接受治疗，患者的累积仍在继续，其他地点正在开放。该部门为支持IND而进行的小鼠毒理学实验，以及该部门开发的大量额外文件、研究和标准操作程序，确保了这个世界上第一个使用Pb-212的第一阶段试验将继续进行。因此，该科一直处于真正新颖的转化实验室到床边研究的最前沿。对Pb-212与特异性单克隆抗体及其与化疗药物联合的评估仍在系统地进行。单一剂量的单一靶向放射性核素缺乏癌症治疗的合理基础；假设是联合治疗方式将取得显著的治疗效果。单剂量Pb-212结合临床相关抗体（如曲妥珠单抗或帕尼单抗）的模型系统中，中位生存期的显著增加已被证明与吉西他滨、紫杉醇或卡铂联合使用。有关了解体内细胞过程参与肿瘤根除的实际机制研究尚不存在。本节报道了前3项此类研究，以确定细胞水平上对高let辐射的损伤反应和修复的生物学机制以及细胞生物学的遗传调控。基线研究表明，不仅双链断裂普遍存在，而且DNA修复机制受损，细胞凋亡增强，细胞周期受到影响。吉西他滨的纳入证明了该药物如何促进治疗，而正在进行的将紫杉醇纳入治疗方案的研究评估了该药物对治疗机制的影响。平行基因图谱研究已完成，第一篇已发表，第二篇已提交发表，第三篇正在准备中。有关结合放射性核素成像（SPECT或PET）和含聚乙二醇的近红外染料（光学成像）的三功能显像剂的研究继续进行。关于自聚集、共价键与非共价键的关键发现，以及适当的表征，使大量文献受到质疑。这一进展为创建直接定量双模态分子显像剂提供了对基础化学的真正理解。继续进行合作研究；提供试剂和/或专业知识，以方便所有研究人员迅速进行实验，以充分确定靶向放射治疗的临床影响。为此，该科继续与代谢科、NCI和路德维希研究所进行非常强有力的合作，并将这一活动充分扩展到与AREVA Med和UAB的合作关系，将Pb-212转化为治疗传播性卵巢癌的首个临床试验，同时将at -211合作扩展到约翰霍普金斯大学的研究人员。

Tumor associated monoclonal antibodies (mAbs) are therapeutic agents when used as selective carriers of cytotoxic agents to malignancies. This hypothesis is tested in animal model systems with mAbs directed toward antigens associated with human disease. The cytocidal agents employed are particle emitting radionuclides. The relative efficacy is evaluated in the appropriately validated murine tumor xenograft model system. The radionuclides chosen focus on appropriate alpha emitters and beta emitters. Current research continues to focus on Pb-212, a beta-emitting alpha particle source, in parallel with the alpha emitter, At-211. Ongoing pre-clinical trials employ chelating agents 1B4M-DTPA (aka MX-DTPA or tiuxetan) or CHX-A (double prime) DTPA. Both are well established in clinical applications; the former is a component of, Zevalin. The chemistry that makes Zevalin, the 1st FDA approved radiolabeled antibody therapeutic, possible was developed by the Chemistry Section. Nearly all ongoing studies now employ the 3rd generation bifunctional chelating agent, CHX-A (double prime) DTPA for sequestering In-111, Y-90, Bi-213, and Lu-177. Prior studies validated the use of CHX-A (double prime) DTPA in PET imaging with the cyclotron produced (refined and purified by the Chemistry Section) Y-86 through the number of PET imaging studies recently reported by the Chemistry Section regarding applications of Y-86 for PET imaging targeting HER2 and HER1(EGFR) for visualizing a variety of diseases such ovarian, colorectal, pancreatic, prostate cancer. Related studies on Y-86 for PET imaging targeting HER1(EGFR) for imaging mesothelioma have been published. Complementary to the development of Y-86 for immunoPET, the Chemistry Section continues to develop novel and superior bifunctional chelating agent useful for Zr-89 immunoPET. The current technology is cumbersome and not stable in vivo leading to bone deposition of released Zr-89. Lead compounds of significantly greater Zr-89 complex stability developed through this program of study have now been published and creation of bifunctional analogs has been achieved. Evaluation of these agents has started. Pre-clinical evaluation of novel bifunctional chelating agents and linkers for targeted radiotherapy continues to refine conjugation chemistry options and radiolabeling improvements. These refinements stem from provision of agents for peptide chemistry as well as for site-specific conjugation strategies amenable for use with both radio-lanthanides and alpha-particle emitting radionuclides. Novel linkage chemistry agents for site-specific linkage strategies such as click chemistry and carbohydrate modification strategies have been created. Pre-clinical At-211 studies have been initiated with dose escalation survival studies targeting HER2 linking At-211 to trastuzumab employing the linker reagent, N-Me-SAPS. Replication of these studies with inclusion of toxicity assessments will provide an optimal dose for extension forward into long-term therapy studies. At-211 has been produced and supplied to collaborators at Johns Hopkins in an effort to establish an At-211 users/ investigators consortium to accelerate evaluation of the therapy potentials of this radionuclide and its clinical translation. The highly extensive and focused pre-clinical investigation into the use of Pb-212 continues for the treatment of disseminated intraperitoneal disease, e.g., from either ovarian or pancreatic cancer. Development of Pb-212 continued through to an open Phase I clinical trial with 14 patients treated, patient accrual continuing, and additional sites being opened. Murine toxicology experiments by the Section in support of the IND along with development of numerous additional documents, studies, and SOPs by the Section insured this Phase 1 trial, the first in the world using Pb-212, would proceed forward. Thus, the Section has routinely been at the forefront of truly novel translational bench to bedside research. Evaluation of Pb-212 with specific mAbs and their combinations with chemotherapeutics continues systematically. A single dose of a single, targeted radionuclide lacks a rational basis for cancer therapy; the hypothesis is that combined modality therapies will achieve significant therapeutic enhancements. Substantial increases in median survival in model systems with single doses of Pb-212 conjugated to clinically relevant antibodies, e.g., trastuzumab or panitumumab have been achieved in combination with gemcitabine, paclitaxel, or carboplatin have been demonstrated. Actual mechanistic studies related to understanding in vivo cellular processes involved in tumor eradication are non-existent. The first 3 such studies have been reported by the Section to define the biological mechanisms at the cellular level of both damage response and repair as well as genetic regulation of the cell biology in response to high-LET radiation. Baseline studies revealed that not only are double strand break prevalent, but that the DNA repair mechanisms are compromised, that apoptosis is enhanced, and that cell cycle impacted. Inclusion of gemcitabine demonstrated how that drug promoted therapy, while ongoing studies integrating taxol into the therapy regimen assess the impact of that drugs mechanism on this therapy. Parallel genetic profiling studies have been completed with the first published, the 2nd submitted for publication, and the 3rd in preparation. Studies pertaining to trifunctional imaging agents combining radionuclidic imaging (SPECT or PET) and NIR dye (Optical imaging) incorporating PEG continue. Critical discoveries regarding self-aggregation, convalent vs. non-covalent bonding, and appropriate characterization puts a significant body of literature in doubt. This advance provides real understanding of basic chemistry for creation of directly quantitative dual modality molecular imaging agents. Collaborative studies continue to be executed; reagents and/or expertise are supplied to facilitate all researchers to expeditiously perform experiments to fully define the clinical impact of targeted radiation therapy. To this end, the Section continues to enjoy very strong and potent collaborations with the Metabolism Branch, NCI and with the Ludwig Institute, and has fully extended this activity to a collaborative relationship with AREVA Med and UAB to translate Pb-212 into its first clinical trial for treatment of disseminated ovarian cancer while extending At-211 collaborations to researchers at Johns Hopkins.