Development of Drug Detoxifying Bacteria for Chemotherapy Induced Gut Injury

点击翻译按钮获取中文摘要

PROJECT SUMMARY/ ABSTRACT Irinotecan-based chemotherapy is widely used for the treatment of various types of metastatic cancers, however, severe drug-induced injury or gastrointestinal (GI) toxicity, especially severe delayed-onset diarrhea (SDOD) induced by SN-38 (an active metabolite of irinotecan), limits its clinical application of the drug. Irinotecan-induced SDOD incidences result in increased healthcare cost due to hospitalization, and poor quality of life and therapeutic outcomes for the cancer patients. Currently, there is no effective treatment available for about ~15% of patients receiving irinotecan therapy, who suffer unmanageable SDOD symptoms, mainly due to their inability to detoxify the SN-38 in the colon. SN-38 mediated intestinal toxicity was found to be more severe in patients with uridine diphosphate glycosyltransferases 1A1 (UGT1A1) polymorphism, delineating the critical role of colonic UGT1A1 in the prevention of SN-38 induced SDOD. Various approaches to reduce SN-38 colonic exposure has been tried without much success, and SDOD remains unmanageable dose-limiting toxicity of irinotecan in adult and pediatric cancer patients. Preliminary research of our academic research collaborators at the University of North Texas and the University of Houston discovered glucosyltransferases from plant Medicago truncatula that could efficiently metabolize typical human UGT1A1 substrates, including SN-38, in an in vitro assay. This led to the novel and innovative concept of bioengineering commensal bacteria E.coli (EC) for overexpressing plant UGT71G1 to create a drug detoxifying bacteria (DDB) that can detoxify SN-38. In this STTR project, we propose to generate proof-of-concept preclinical evidence in support of developing a safe, efficacious, and traceable DDB as a novel live biotherapeutic product (LBP) to alleviate and/or prevent the SN- 38-mediated intestinal toxicity. Here, we will bioengineer a commensal E.coli strain, with good human gut colonization potential, to overexpress the most active variant of UGT71G1 (U71G1*n) tagged with a green fluorescent protein (GFP), which will be delivered in a protective capsule directly to the colon for the effective glycosylation of SN-38 to SN-38-glucose. To achieve this goal, the proposed specific aims are 1) to develop traceable and more active drug detoxifying bacteria EC_U71G1*n (active variant) to detoxify SN-38, 2) to develop a colon-optimized capsule delivery of traceable and highly active lyophilized DDBs, and 3) to evaluate the efficacy of 2 colon-delivered DDBs in irinotecan induced SDOD rat model. An active DDB engineered with pUGT biocatalyst (for the detoxification of SN-38) and GFP (for tracing the effective gut colonization in human feces for therapeutic efficacy monitoring) will accelerate the recovery of cancer patients from SDOD, and lead to the effective management of irinotecan-induced SDOD in clinics. The success of this project will provide Sanarentero with the proof-of-concept evidence needed for developing an SN-38-targeted traceable DDB for preclinical and IND-enabling studies in a phase-II SBIR/STTR application. The novel LBP will act as a complementary therapy to treat SDOD, which should improve the quality of life and even therapeutic outcomes for metastatic cancer patients. Once successful in this endeavor, we plan to apply the same approach to utilize different plant UGTs for inactivating other GI-toxic drugs, xenobiotics, pollutants, or their toxic metabolites in the colon by developing drug-specific DDB.