Treating Heart Dysfunction Related to Cancer Therapy With Sacubitril/Valsartan

This trial is testing sacubitril/valsartan (a heart failure medication also known as Entresto) in children and young adults who developed heart dysfunction as a side effect of anthracycline chemotherapy — a common type of cancer treatment. The study aims to improve heart function before symptoms develop. **You may be eligible if...** - You were 39 years old or younger at the time of your cancer diagnosis - You received anthracycline chemotherapy (such as doxorubicin) - Your heart function shows early signs of damage (reduced strain or slightly reduced ejection fraction of 40–lower limit of normal) on an echocardiogram - You currently have no symptoms of heart failure (no shortness of breath, fatigue, or swelling at rest or with normal activity) **You may NOT be eligible if...** - You are under 18 years old - You have severe kidney disease (GFR below 30) - You have high potassium levels in your blood - You have known significant heart valve disease, congenital heart disease, or cardiomyopathy unrelated to treatment - You are pregnant or breastfeeding - You are currently taking ACE inhibitors, ARBs, or other medications that interact with sacubitril/valsartan Talk to your doctor to see if this trial is right for you.