Abstract 1384: CRLX101, an investigational camptothecin-containing nanoparticle-drug conjugate, reverses the HIF-1α-mediated increase in cancer stem cells caused by bevacizumab in a preclinical model of triple-negative breast cancer

Antiangiogenic agents are designed to impede the development of new tumor blood vessels, thereby starving tumors of oxygen and nutrients to ultimately block tumor growth. Despite advances made in developing antiangiogenic therapies, clinical and preclinical data suggest that these drugs have limited efficacy in breast cancer patients. Tumors inevitably develop resistance to antiangiogenic agents and patients frequently fail to demonstrate significantly better overall survival. Acquired resistance to antiangiogenic agents has been attributed in part to the induction of intra-tumoral hypoxia and the concomitant stabilization of hypoxia-inducible factor 1α (HIF-1α), a transcription factor that promotes tumor angiogenesis, invasion, metastasis, and cancer stem cell (CSC) self-renewal. In this preclinical model, we demonstrate that CRLX101, an investigational nanoparticle-drug conjugate (NDC) containing the payload camptothecin (CPT), can reverse the stimulatory effects of hypoxia on the CSC population in an orthotopic triple-negative xenograft model. The payload, camptothecin, a topoisomerase 1 inhibitor, inhibits HIF-1α protein accumulation at concentrations below those that were cytotoxic to tumor cells, and inhibits hypoxia-mediated CSC induction at these low concentrations in vitro. In an orthotopic triple-negative breast cancer model, CRLX101 is synergistic with bevacizumab. Tumor reimplantation experiments confirm that the combination therapy effectively targets both the bulk tumor cell and CSC populations. Results generated from these preclinical studies support the clinical research of combining antiangiogenic agents with CRLX101 to increase patient survival. CRLX101 is currently in phase 2 clinical trials in combination with bevacizumab in both recurrent ovarian cancer and metastatic renal cell carcinoma. Citation Format: Sarah J. Conley, Trenton L. Baker, Joseph P. Burnet, Rebecca L. Thiesen, Douglas Lazarus, Christian G. Peters, Shawn G. Clouthier, Scott Eliasof, Max S. Wicha. CRLX101, an investigational camptothecin-containing nanoparticle-drug conjugate, reverses the HIF-1α-mediated increase in cancer stem cells caused by bevacizumab in a preclinical model of triple-negative breast cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1384. doi:10.1158/1538-7445.AM2015-1384