Synthesis and Pre-Clinical Evaluation of Targeted, Iron-Based MRI Contrast Agents

标题：完整的项目A--靶向铁基MRI对比剂的合成和临床前评估 加强卵巢癌检测和治疗计划的药物 共同领导：MDACC-Jim Klostergaard，博士，分子与工程系教授 细胞肿瘤学 UPRCCC-Raphael G.Raptis，博士，化学系教授 摘要 卵巢癌仍然是最致命的妇科恶性肿瘤，只有在 过去几十年的存活率。由于缺乏适当的筛查目标和明确的 风险因素对于大多数卵巢癌来说，腹膜已有癌性受累 在大多数新诊断的患者中，不祥的是，这种肿瘤负担经常决定患者的存活率。 非侵入性检测已在腹膜内的卵巢癌早期疗效 去茎后微小残留疾病的背景，以及检测到最早的 这种疾病在治疗诱导缓解后复发，对理想的患者来说可能被证明是无价的 管理和治疗干预。 具体地说，对于这一临床前提案，我们计划对两种初始治疗的临床情景进行建模 监测III/IV期患者，以及检测他们最早复发的情况，以表明有必要进一步 干预。未来验证的一个关键方面将是与CA-125水平(或与 可能是在过渡期间发展的)，在进入缓解期和作为预后指标 旧病复发。目前，卵巢癌的监测通常依赖于血清CA-125和 诊断成像，最常见的是计算机断层扫描或超声波，在这种情况下， 磁共振成像(MRI)是一种相对未得到充分利用的手段。我们建议通过改进使用 靶向对比剂(CA)、MRI在监测中可发挥重要作用。 构成这一提议基础的首要假设是：1)铁基的cas先生将 优于基于Gd(Gd)和超顺磁性氧化铁(SPIO)的那些，2)在临床前 卵巢癌模型，我们基于铁簇的新型CA将增强MR成像能力 与目前的技术相比，以及3)肿瘤靶向CA将提供更好的肿瘤检测 与非目标CA相比。 在这项计划中，我们将合成和评估一系列新的铁基磁共振成像CA，以尝试 加强对播散到腹膜的卵巢肿瘤的检测。重点将放在人类卵巢上 肿瘤/裸鼠异种移植模型，采用腹膜腔内注射。植入。这些肿瘤模型反映了 许多与人类疾病相关的方面，是细胞表面蛋白多糖的高表达者， CD44在高达90%的人卵巢癌标本中过度表达。在 临床情况，CD44在肿瘤组织上的表达将在手术去髓鞘时得到证实。 透明质酸(HA)是CD44的配体，是腹膜间皮细胞的组成部分。HA将结合在一起 以创建一种新的CA先导配方，专门针对CD44(+)肿瘤。 拟议研究的具体目标包括：1)评估非目标以及 专有Fe8-铅化合物及其水溶性结合物的靶向制剂以增强磁共振 IP的成像。人卵巢癌异种移植模型；2)开发/筛选高亲和力硫代核酸 对于CD44家族成员、亲本和/或选定的剪接变异体；以及3)合成适当的 铅Fe8-簇的化学官能化衍生物，这将允许连接抗CD44 以确定CD44适配子-Fe8-簇偶联物是否提高了MR成像的敏感性 就是IP。CD44(+)卵巢癌移植瘤与HA-Fe8 CA以及非靶向移植瘤的比较 复合体。 我们的目标和期望是，在本研究结束时，我们将能够选择一位首席CA 用于进一步的临床前开发的配方，并随后跟踪到临床评估。使用 最近的临床试验结果表明，使用基于I.P的药物治疗方案的证据令人信服， 这种磁共振成像的可用性和相关的非侵入性序列成像灵敏度的改善 在目前诊断为CD44(+)的肿瘤中，腹膜肿瘤的负担可能会找到一个重要的临床利基 成像技术不够理想(例如结直肠癌腹膜转移)。

TITLE: Full Project A - Synthesis and Pre-Clinical Evaluation of Targeted, Iron-Based MRI Contrast Agents to Enhance Ovarian Cancer Detection and Treatment Scheduling CO-LEADERS: MDACC - Jim Klostergaard, Ph.D., Professor, Department of Molecular & Cellular Oncology UPRCCC - Raphael G. Raptis, Ph.D., Professor, Department of Chemistry ABSTRACT Ovarian cancer remains the most lethal gynecologic malignancy, with only incremental improvements in survival rates over the last decades. Due to the absence of appropriate screening targets and clearly-defined risk factors for the majority of ovarian cancers, carcinomatous involvement of the peritoneum is already present in the majority of newly-diagnosed patients; ominously, this tumor burden alone frequently determines survival. Non-invasive detection of early therapeutic responses of ovarian cancer already in the peritoneum in the contexts of minimal residual disease following debulking, as well as detection of the earliest evidence of relapse of such disease after treatment-induced remission, might prove invaluable for optimal patient management and treatment intervention. Specifically, for this pre-clinical proposal, we plan to model the clinical scenarios of both initial treatment monitoring of stage III/IV patients, as well as the detection of their earliest relapse to signal the need for further intervention. A key aspect of future validation would be comparison to CA-125 levels (or to other markers that may have been developed in the interim), both during entry into remission and as a prognostic indicator of relapse. Currently, ovarian cancer monitoring typically depends on a combination of serum CA-125 and diagnostic imaging, most frequently computed tomography or ultrasound, and in this setting magnetic resonance imaging (MRI) is a comparatively under-utilized modality. We propose that with improved use of targeted contrast agents (CAs), MRI could play a valuable role in monitoring. The overarching hypotheses that form the basis for this proposal are 1) that iron-based MR CAs will be superior to those based on gadolinium (Gd) and superparamagnetic iron oxides (SPIOs), 2) that in preclinical ovarian cancer models, our novel iron-cluster-based CAs will enhance MR imaging capabilities compared to current technigues, and 3) that tumor-targeted CAs will provide superior detection of tumors compared to non-targeted CAs. In this proposal, we will synthesize and evaluate a novel series of Fe-based MRI CAs to attempt to enhance detection of ovarian tumors disseminated to the peritoneum. The focus will be on human ovarian carcinoma/nude mouse xenograft models, using intraperitoneal (i.p.) implantation. These tumor models reflect numerous relevant aspects of the human disease, and are high expressors of the cell-surface proteoglycan, CD44, which is over-expressed on as many as 90% of human ovarian carcinoma specimens. In the clinical scenario, CD44 expression on tumor tissue would be confirmed at the time of surgical debulking. Hyaluronic acid (HA), a component of the peritoneal mesothelium, is a ligand of CD44. HA will be conjugated to a CA "module" to create a novel lead formulation of a CA, specifically targeted to CD44(+) tumors. Specific aims for the proposed studies include: 1) To evaluate the ability of non-targeted as well as targeted formulations of the proprietary lead Fe8-compound and its water-soluble conjugates to enhance MR imaging of i.p. human ovarian carcinoma xenograft models; 2) To develop/select thioaptamers with high affinity for CD44 family members, parental and/or selected splice variants; and 3) To synthesize appropriate chemically functionalized derivatives of the lead Fe8-cluster, which will allow the attachment of the anti-CD44 aptamers; to determine whether the CD44 aptamer-Fe8-cluster conjugate improves the MR imaging sensitivity of i.p. CD44(+) ovarian carcinoma xenografts, by comparison to the HA-Fe8 CA, as well as to non-targeted complexes. Our goal and expectation is that at the end of this study, we will be in a position to select a lead CA formulation for further pre-clinical development and to subsequently follow a track to clinical evaluation. With recent clinical trial results demonstrating compelling evidence for the use of i.p-based drug treatment protocols, the availability of such MRI CAs and the associated improvements in sensitivity for non-invasive, serial imaging of peritoneal tumor burden may find a significant clinical niche in CD44(+) tumors where current diagnostic imaging techniques are suboptimal (e.g. colorectal cancer peritoneal metastases).