Breast cancer patients undergoing trastuzumab-based HER2-directed therapy are at risk of heart function decline or heart failure symptoms, but it is unknown if, when, and for how long cardiovascular protective strategies, e.g. with a beta-blocker, could help. This study randomly assigns those taking curative-intent trastuzumab-based HER2-directed therapy to the beta-blocker carvedilol-either when significant heart function decline or subtle early signs of heart injury (either by elevation of a cardiac blood biomarker, i.e. cardiac troponin, or by an abnormal heart ultrasound marker, i.e. global longitudinal strain) are noted, or preventatively before beginning trastuzumab-based HER2-directed therapy. This study will further randomly assign those patients on carvedilol to either discontinuation at the end of trastuzumab-based HER2-directed therapy or continuation for another year, providing much needed clinical trial data on what the best strategy ("tactic") for those at risk of cardiotoxicity with trastuzumab-based HER2-directed therapy is.

NCT03879629

Conditions

1. Breast Cancer

Interventions

1. Drug: Carvedilol

MeSH:Cardiomyopathies

HPO:Cardiomyopathy

Correlation of absolute delta change in GLS and LVEF while on trastuzumab and after stopping trastuzumab with the frequency of the following SNPs: trastuzumab-related: p<1x10-5 hits from Norton GWAS (six loci) 130 HER 2 Ile665Val, HER2 Pro1170Ala125, 126, 130, anthracycline-related: ABCB1 rs1128503, ABCB4 rs1149222, ABCC1 rs45511401, ABCC2 res17222723, CAT rs10836235, CBR3 rs1056892, CYBA rs4673, CYP3A4*22 rs35599367, NCF4 rs1883112, RAC2 rs13058338, RARG rs2229774, SLC28A3 rs7853758, TOP2B rs10865801, and UGT 1A6*4 rs1786378374, 150-152, beta-blocker-related: β2-AR Gln27Gln, β1-AR Arg389Arg 80-82 and CYP2D6 polymorphisms (CYP2D6 alleles (*1, *2, *3, *4, *5, *6, *7, *8, *9, *10, *11, *15, *17, *19, *20, *29, *35, *36, *40 and *41), as well as 7 CYP2D6 gene duplications (*1 9 N, *2 9 N, *4 9 N, *10 9 N, *17 9 N, *35 9 N and *41 9 N) by use of the AmpliChip CYP450 GeneChip. --- Ile665Val ---