Abstract P3114: Intermittent Fasting Potentiates Anthracycline Cardiotoxicity

Background: Anthracyclines such as doxorubicin (Dox) cause cardiotoxicity and associated autophagic impairment, though controversy exists increasing autophagy ameliorates or exacerbates Dox cardiotoxicity. Because intermittent fasting (IF), a potent stimulus of autophagy, is presently under clinical investigation in multiple human clinical trials of cancer patients receiving chemotherapy, we tested whether IF would ameliorate or exacerbate Dox cardiotoxicity in multiple murine models. Methods: Chow-fed C57BL/6 mice (n=150) were randomized to ad libitum feeding ( adlib ) or IF (every other day) and treated with vehicle or Dox (5 mg/kg IP x 4 doses). Alternatively, to stimulate autophagy and lysosomal biogenesis transcriptionally, we employed adeno-associated virus 9 (AAV9)-driven overexpression of transcription factor EB (TFEB) vs null, followed by vehicle or Dox (n=40). We further analyzed TFEB nuclear content in myocardial tissue from patients with anthracycline cardiomyopathy vs non-failing donors and patients with other non-ischemic cardiomyopathies (n=17). Results: In Dox-treated mice (but not in vehicle controls), IF significantly reduced survival (18% absolute reduction or AR) ( figure A ), left ventricular ejection fraction (LVEF) (8% AR) ( figure B ) and heart weight index (12% relative reduction) ( figure C ) compared to adlib group. Mechanistically, in Dox-treated mice, IF significantly decreased phosphorylation of mammalian target of rapamycin, increased active, nuclear TFEB content, and increased levels of the atrophy factor muscle RING-finger protein-1. In myocardial tissue from patients with anthracycline cardiomyopathy, we observed a 3.5-fold increase (p<0.01) in nuclear TFEB content compared to both tissues from donors without heart failure and tissues from patients with other non-ischemic cardiomyopathies. Overexpression of TFEB exacerbated Dox-induced cardiotoxicity, including significant decreases in LVEF, left ventricular mass index, and survival. Conclusions: IF exacerbates Dox-related mortality and cardiomyopathy, likely by stimulating the autophagy-lysosomal transcriptional regulator TFEB. Our data raise concerns about the safety of IF and augmentation of TFEB activity in the context of anthracycline chemotherapy.