OPTIMIZING CANCER CHEMOTHERAPY

尽管最近出现了令人兴奋的有效抗癌治疗药物的新武器库(如脂质体药物、基因疗法、放射性标记抗体和毒素)，但选择性地将足够浓度的这些新药物输送到构成大于1-2厘米的原发和转移癌的肿瘤细胞仍然是一个问题。我们建议，全身热疗(WBH)，可以用来增加药物对肿瘤的递送和细胞毒性，同时保留正常组织。WBH可以(I)增加肿瘤微血管的通透性，(Ii)增加药物通过肿瘤细胞膜的能力，(Iii)促进药物从脂质体中释放，(Iv)通过增加药物与亚细胞靶点(如DNA)的相互作用而增加直接的细胞毒性，(V)抑制药物引起的细胞损伤的修复，以及(Vi)破坏肿瘤微血管，从而限制肿瘤的生长和转移。本提案侧重于第(一)、(三)和(六)方面。其具体目的是：A)利用WBH通过增加肿瘤微血管的通透性来增加脂质体对肿瘤的输送；B)一旦脂质体在肿瘤中积累，就使用WBH来刺激和同步脂质体的药物释放；C)将脂质体药物与两个旨在靶向微血管通透性的热组分结合起来，使药物从脂质体中同步释放，以平衡肿瘤控制，通过直接的内皮细胞毒性和微血管破坏实现与正常组织毒性的平衡。我们建议通过给Fischer大鼠注射精心设计的WBH和Doxil(多柔比星包裹在聚乙二醇化的、空间稳定的脂质体中)来实现这一点，这些大鼠原位接种了MTLn3乳腺癌，并自发转移到淋巴结。WBH为LL-WBH[长期(6h)，低温(发热)39.5-40.0℃)WHB]和SH-WBH[短期(1h)，高温(41.5℃)WBH]。为了确定这些治疗的有效性，我们将量化a)原发和转移性肿瘤反应，b)正常组织反应，c)血浆药物浓度和药物在肿瘤和正常组织中的积聚作为时间的函数(药代动力学)，d)VPF/VEGF和Flk-1/KDR水平指示的微血管通透性作为时间的函数，以及e)肿瘤微血管密度的时间进程。最终目标是开发一种治疗方法，它使用多个热部位，结合脂质体包封剂，靶向肿瘤新生血管的两个不同方面，以增强肿瘤毒性。该提案中探讨的战略与许多创新的新治疗剂的交付直接相关。我们希望通过这样一种高温介导的多管齐下的攻击，显著提高常见癌症患者的存活率和生活质量。

Despite the recent appearance of an exciting new arsenal of effective anti-cancer therapeutic agents (e.g. liposomal drugs, gene therapies, radiolabeled antibodies, and toxins), selectively delivering adequate concentrations of these new agents to tumor cells making up primary and metastatic cancers larger than 1 - 2 cm remains a problem. We propose that whoel body hyperthermia (WBH), can be used to increase both the delivery and cytotoxicity of drugs to tumors, while sparing normal tissue. WBH can (i) increase the permeability of tumor microvasculature, (ii) increase drug passage across the tumor cell membrane, (iii) stimulate release of drugs from liposomes, (iv) increase direct cytotoxicity by increasing the interaction of drugs with sub-cellular targets such as DNA (v) inhibit the repair of drug-induced cellular damage, and (vi) destroy tumor microvasculature, thereby limiting tumor growth and metastasis. This proposal focuses on aspects (i), (iii), and (vi). The specific aims are A) to use WBH to increase liposome delivery to tumor by increasing tumor microvascular permeability; B) to use WBH once liposomes have accumulated in the tumor to stimulate and synchronize release of drug from the liposome; C) to combine liposomal drug with two heat fractions designed to target microvessel permeability and synchronize drug release from the liposomes in a way which balances tumor control, achieved through direct endothelial cytotoxicity and microvessel destruction, with normal tissue toxicity. We propose to achieve this by administering carefully designed combinations of WBH and Doxil (doxorubicin encapsulated in a pegylated, sterically stabilized liposome) to Fischer rats bearing orthotopically inoculated MTLn3 mammary adenocarcinomas which spontaneously metastasize to lymph nodes. WBH will be administered as LL-WBH [long-duration (6h), low-temperature (fever-like) 39.5-40.0 C) WHB) and SH-WBH [short-duration (1 h), high temperature (41.5 C) WBH]. In order to determine the efficacy of these treatments, we will quantify a) primary and metastatic tumor response, b) normal tissue response, c) plasma drug concentration and drug accumulation in tumor and normal tissues as a function of time (pharmacokinetics), d) microvessel permeability as indicated by VPF/VEGF and Flk-1/KDR levels as a function of time, and e) the time course of tumor microvascular density. The ultimate goal is to develop a treatment, which uses multiple heat fractions, together with liposome-encapsulated agents, to target two different aspects of tumor neovasculature to enhance tumor toxicity. The strategy explored in this proposal has direct relevance to the delivery of many of the innovative, new therapeutic agents. Through such a hyperthermia-mediated multi- pronged attack, we hope to significantly increase the survival and quality of life of patients with common cancers.