Abstract 17055: Novel Dual mTOR Inhibitor/AMPK Activator Mitigates Doxorubicin Cardiotoxicity and Potentiates Its Chemotherapeutic Efficacy Against Triple Negative Breast Cancer

Abstract

Background: Doxorubicin (DOX) is a first-line anticancer drug for the treatment of triple negative breast cancer (TNBC). However, its dose-dependent delayed and progressive cardiotoxicity limits its therapeutic application. NovoMedix (NM922) is a novel dual mTOR inhibitor/AMPK activator that was shown to attenuate adverse cardiac remodeling and fibrosis in a pressure-overload mouse model of heart failure. We investigated whether combination therapy with DOX and NM922 exhibits synergistic chemotherapeutic effect while mitigating DOX cardiotoxicity. Methods & Results: Tumors were generated in athymic female BALB/cAnNCr-nu/nu mice by implanting MDA-MB-231 cells into the rear right flank. Mice with tumors (volume≈200mm 3 ) were randomized into 6 groups and treated as follows: 1) Control (n=10); 2) DOX (3 mg/kg; i.p. twice weekly, total 15 mg/kg; n=10); 3) NM922 (25 mg/kg/d; p.o. n=5); 4) DOX+NM922 (25 mg/kg/d; p.o. n=15); 5) NM922 (100 mg/kg/d; p.o. n=5); 6) DOX+NM922 (100 mg/kg/d; p.o. n=15). Tumor size, body weight and cardiac function were assessed throughout the study. DOX alone, and to a significant extent when in combination with NM922 (25 mg/kg) reduced tumor growth compared to control. NM922 (100 mg/kg) with/without DOX significantly reduced tumor growth as compared to DOX alone (Fig A). DOX caused reduction in body weight and survival of tumor-bearing mice. NM922 did not prevent DOX-induced cachexia, but significantly improved survival in DOX-treated mice (Fig B). DOX treatment caused a significant decline in left ventricular ejection fraction compared to control over 3 weeks, which was ameliorated with NM922 (100 mg/kg) co-treatment (Fig C&D). Conclusion: Our results suggest that NM922 may potentiate the chemotherapeutic efficacy of DOX in TNBC, while mitigating its cardiotoxicity. Moreover, these findings advocate the potential efficacy of utilizing lower DOX dosages when combined with NM922, which would have significant clinical implications.