Prediction and prognostic validation of colorectal cancer therapeutic effect of WM-S1-030 using pre-clinical CTC animal model.

Abstract

e15557 Background: CTC (Circulating tumor cells) has the advantage of being able to effectively investigate non-invasive diagnosis, prediction, and prognosis for non-surgical carcinoma or tissue sample collection. We have developed WM-S1-030 (WMBIO) as a novel inhibitor for mtRTK (mutant receptor tyrosine kinase) identified important targets for cancer progression and metastasis in various cancers, including colorectal cancer, and have tried to prove the possibility of CTC diagnosis, prediction and prognosis of WM-S1-030 using tumor animal models. Methods: Six of colon cancer cell lines expressing mtRTK (pTyr-mtRTK) were transplanted into Balb.c nude mice and NSG mice to collect peripheral blood when the tumor size reached 1000 mm3. CTCs were quantified in peripheral blood using the Smart Biopsy cell isolator (Cytogen). The expression of pTyr-mtRTK in CTCs was analyzed via the Smart Biopsy Image Analyzer (Cytogen). Colon cancer cell lines expressing pTyr-mtRTK were transplanted into NSG mice and we examined the tumor suppression, the enumeration of CTCs and pTyr-mtRTK expression in CTCs after administration of WM-S1-030. We also identified CTCs in peripheral blood of colon cancer patients and analyzed expression of pTyr-mtRTK in CTCs through Smart Biopsy system. Results: As results of the enumeration of CTCs after tumor transplantation into Balb.c nude mice and NSG mice, the number of CTC was 8 ~ 20 times higher peripheral blood in the NSG model, which indicates innate immune responses are critical for the survival of CTCs. Half of CTCs isolated from the blood expressed pTyr-mtRTK. The tumor size, the number of CTCs, and the expression of pTyr-mtRTK in CTCs were examined after the administration of WM-S1-030. The volume of tumor decreased by 67% in the WM-S1-030 group compared to the vehicle. The number of CTCs was reduced by approximately three times after the treatment of WM-S1-030 and also the number of CTCs expressing pTyr-mtRTK was significantly decreased. CTC detection and pTyr-mtRTK expression analysis in the peripheral blood of colon cancer patients detected 9 CTCs per 10 ml of peripheral blood, of which 11 % of CTCs representing pTyr-mtRTK were confirmed. Conclusions: WM-S1-030 was developed and confirmed in the CTC-based animal model, which implies that the analysis of CTCs is the powerful tool for predicting/ prognosing WM-S1-030 in the pre-clinical analysis. Currently, we are conducting clinical diagnostic validation using CTC in the blood of colorectal cancer patients and preparing for clinical trial of WM-S1-030.