A chemoenzymatic technology for the efficient synthesis of novel cryptophycins

描述（由申请人提供）：隐菌素是一种结构多样的聚酮类/非核糖体肽天然产物，具有强大的抗癌活性。然而，尽管有这种令人印象深刻的活性，隐菌素发展成为一种有益的癌症化疗药物，却遭受了与治疗相关的临床显着的神经毒性。尽管如此，这种天然产物有前景的治疗光谱促使Acera Biosciences Inc.继续探索和开发一种可以重新进入临床评估的隐藻素化合物。在这项发现工作中，该公司寻求生成大型的、结构多样的隐藻素化合物文库，用于随后的生物活性筛选。由于隐苔素天然产物的化学结构复杂，具有多个立体中心、一个大内酯环和一个活性的2-环氧化物部分，因此通过传统的合成方法生成这些化合物需要多个步骤，导致总收率低，每个化合物的成本高。因此，这些方法不适合快速生产结构多样的化合物。因此，在这个I期STTR提案中，Acera将开发一种新的高通量合成技术，使多种隐藻素类似物能够快速筛选所需的药理学特性。这个创新的合成平台旨在利用常规固相合成来构建含有线性隐藻中间体的化合物文库。所提出的策略的标志包括将线性隐藻中间体转化为成熟的大环隐藻类似物的化学酶。特别是，Acera Biosciences Inc.寻求利用隐藻素硫酯酶（Crp TE）和隐藻素环氧化酶（CrpE）的催化能力，特异性和有效地将树脂结合的中间体转化为具有关键环氧化物官能团的大环化合物。为了确定这种方法的可行性，本研究旨在通过18种市售的苯丙氨酸类似物取代，将结构多样性纳入3-氯- o-甲基-酪氨酸隐藻合成物中。由此产生的18种新型隐藻素化合物将使用亨利福特健康系统开发的多方面临床前药物开发范式进行抗肿瘤活性和神经毒性筛选。该策略的一个关键特征是，需要少量的化合物来鉴定初始先导化合物，使其成为高通量化学酶生产隐藻素类似物的理想补充。一旦建立了概念验证，第二阶段的研究工作将把这项技术应用于产生数千种化学上不同的隐藻素化合物，这些化合物将被筛选为理想的药理活性。确定的先导化合物可以授权给有意扩大其抗癌开发项目的制药或生物技术公司。

DESCRIPTION (provided by applicant): The cryptophycins are a structurally diverse class of polyketide/non-ribosomal peptide natural products that possess potent anticancer activity. However, despite this impressive activity, the development of the cryptophycins into a beneficial cancer chemotherapeutic agent has suffered from clinically significant neurotoxicity that correlates with treatment. Nonetheless, the promising therapeutic spectrum of this natural product has motivated Acera Biosciences Inc. to pursue the discovery and development of a cryptophycin compound that that can re-enter clinical evaluation. Within this discovery effort, the company seeks to generate large, structurally diverse libraries of cryptophycin compounds for subsequent biological activity screening. Due to the complex chemical structure of the cryptophycin natural products, which features multiple stereocenters, a macrolactone ring, and a reactive 2-epoxide moiety, the generation of these compounds by traditional synthetic methods requires multiple steps, resulting in low overall yields and a high cost per compound. As such, these methods are not amenable to the rapid production of structurally diverse compounds. Accordingly, in this Phase I STTR proposal, Acera will develop a novel high throughput synthetic technology that will enable access to a diversity of cryptophycin analogues that can be rapidly screened for desirable pharmacological properties. This innovative synthetic platform seeks to utilize routine solid-phase synthesis for the construction of compound libraries containing linear cryptophycin intermediates. The hallmark of the proposed strategy involves chemoenzymatic transformation of the linear cryptophycin intermediates into mature, macrocyclic cryptophycin analogues. In particular, Acera Biosciences Inc. seeks to leverage the catalytic power of the cryptophycin thioesterase (Crp TE) and the cryptophycin epoxidase (CrpE) to specifically and efficiently transform the resin-bound intermediates to macrocyclic compounds bearing the key epoxide functional group. To establish the feasibility of this approach, this proposed research aims to incorporate structural diversity into the 3-chloro-O-methyl-tyrosyl cryptophycin synthon via substitution with 18 commercially available phenylalanine analogues. The resulting 18 novel cryptophycin compounds will be screened for anti-tumor activity and neurotoxicity using a multi-faceted preclinical drug development paradigm developed at Henry Ford Health System. A key feature of this strategy is that small quantities of compounds are required to identify an initial lead compound, making it an ideal complement to the high throughput chemoenzymatic production of cryptophycin analogues. Once proof-of-concept is established, research efforts in Phase II will apply this technology toward the generation of thousands of chemically diverse cryptophycin compounds that will be screened for desirable pharmacological activity. Identified lead compounds can then be licensed to pharmaceutical or biotechnology companies interested in expanding their anti-cancer development programs. PUBLIC HEALTH RELEVANCE: Cancer represents a significant global human health concern that justifies substantial research investments for the discovery and development of novel treatments. Cryptophycin is a known, potent anti-cancer compound that has been dropped from clinical testing due to intolerable side-effects. This proposed research seeks to develop a novel technology for the rapid generation of cryptophycin analogues that may display fewer side effects, thereby enabling cryptophycin to be utilized by physicians in the battle against this often deadly disease.