Based on the cardioprotective role of neuregulin-1 (NRG-1), clinical trials assessing its safety and efficacy in HF are currently underway.40 Cardiotoxicity with anti-HER2 TKIs was seen at a higher rate in metastatic trials compared to adjuvant trials.28 In a meta-analysis evaluating the cardiac adverse events of anti-HER2 drug lapatinib-treated patients, the overall incidence associated with breast cancer was found to be higher than in other cancers (3% vs 2.7%). Here, NRG1 is linked to hydrops fetalis.