Abstract 1407: A dual functional activity subdues the growth of consensus molecular subtypes 1 and 4 in colorectal cancer xenografts

Abstract

Abstract Purpose: We have synthesized a bifunctional hybrid molecule BO-2762, which is able to induce DNA damage and inhibit angiogenesis simultaneously [1] as similar to first-line chemotherapy combination (FOLFOX + Bevacizumab). Recently, colorectal cancers (CRC) were classified into four consensus molecular types (CMS) [2], CMS 1 to 4. We carried out a translational study to investigate the anti-CRC activity of BO-2762 to various CMS subtypes. Experimental Design: We performed in vitro and in vivo studies to determine the potency and selectivity of first-line combo like hybrid small molecule BO-2762 on a panel of CRC cell lines, which were classified into CMS-1 (LoVo & DLD-1), CMS-2 (LS1034 & SW116), CMS-3 (HT-29 & LS174T), CMS-4 (SW620 & CACO2) and several unclassified cell lines (HCT-116, RKO, & COLO205). Immunohistochemistry was adopted to determine the DNA damage marker (γH2AX) and blood vessel marker (CD31) in the tumor xenografts treated with BO-2762. Results: BO-2762 alone has bifunctional activity by lodging DNA crosslinking in CRC cells and inhibiting tube formation of HUVEC cells at IC50 of 0.50 to 3 μM range. Angiogenesis inhibition was possibly due to the suppression of VEGFR-2 phosphorylation in HUVEC cells and the depletion of VEGF-A in the conditioned media. As reported in previous studies [3], we did not observe non-subtype specific cytotoxicity in in vitro assay system. Intriguingly, animal models exhibited their selective suppression on xenografts of various CMS-1 subtypes, e.g., remarkable suppression in CMS-1 LoVo cells (85.8%) and CMS-4 SW620 cells (83.0%), moderate in CMS-2 LS1034 cells (75.4%), and poor in CMS-3 HT29 cells (44.8%). BO-2762 was administrated at 20 mg/kg via iv injection. Furthermore, by immunohistochemically staining of γH2AX and CD31, we found that BO-2762 was able to induce DNA damage in xenografts of all CMS subtypes but unable to suppress the angiogenesis in CMS-3 HT29 xenografts. Our preliminary results showed enriched VEGF-A and VEGFR2 in HT29 cells. Conclusion: CMS classification paves a medical platform to investigate the combination of anti-angiogenic and DNA crosslinking agents in the CRC selective treatment. BO-2762, a novel hybrid displaying anti-angiogenesis and induction of DNA damage, is functional similar to FOLFOX + Bevacizumab. CMS subtype-specific inhibition in xenografts was likely evented according to their expression levels of angiogenic signaling. Accordingly, BO-2762 has a great potential for further development as a potent and specific anti-CRC agent at least against CMS-1 and 4 subtypes. However, biomarker identification for selecting right patients warrants our further investigation.