The Impact of Using Nicorandil for the Prevention of Doxorubicin-Induced Cardiotoxicity (NICBREASTRCT)

There are different modalities for the treatment of breast cancer, including surgery, chemotherapy, radiotherapy, endocrine therapy, targeted therapy, and immunotherapy. Chemotherapy is important to decrease the tumor size of the breast, making breast conservation possible.

Doxorubicin (DOX) is an anticancer agent used in chemotherapy to treat hematological and solid cancers. In breast cancer, DOX is used in many protocols. One of the well-known chemotherapeutic protocols is AC-T (adriamycin, cyclophosphamide, and paclitaxel). The mechanism of DOX cytotoxicity is due to free radical formation, which is associated with DOX cardiotoxic adverse events. DOX-induced cardiomyopathy leads to fibrosis of myocardial cells that causes cardiovascular disorders. DOX-cardiotoxicity is considered irreversible (type I) cardiotoxicity. Echocardiography remains the gold standard for assessing cardiac function primarily by evaluating the left ventricular ejection fraction (LVEF). Besides, echocardiography could assess the global longitudinal strain (GLS), a measure of the left ventricle's longitudinal shortening, which is more sensitive for detecting early myocardial dysfunction that cannot be assessed by LVEF alone. Changes in GLS can indicate subclinical cardiac impairment, which is considered an early warning sign of doxorubicin-induced cardiotoxicity.

Biomarkers of cardiotoxicity are a non-invasive method for early detection in patients undergoing doxorubicin therapy. These biomarkers enable clinicians to initiate preventive treatment regimens earlier, as they indicate long-term LVEF deterioration. Studies have shown that the risk of DOX cardiotoxicity increases at a cumulative dose of 400 mg/m² without other risk factors. DOX-induced cardiotoxicity may lead to increased morbidity and mortality.

As a consequence, for most of the patients with DOX-induced cardiotoxicity, their quality of life will be affected. One of the methods used for quality of life assessment is the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC) Core 30 (QLQ-C30), and another one for breast cancer patients (BR-42). A study has shown the deterioration in the psychological and physical state of breast cancer patients on chemotherapy treatment.

Many antioxidant supplements are used to treat DOX-induced cardiotoxicity. Dexrazoxane is the only FDA-approved cardioprotective agent for DOX cardiotoxicity. Although other supplements like omega-3, vitamin E, and levocarnitine have shown significant effects in preclinical studies, only a few have been investigated in clinical practice. Yet, few studies have targeted the Ca²⁺ imbalance caused by DOX administration.

Nicorandil (NIC), a nicotinamide ester with a nitrate group, is used in several medical conditions in Japan and Europe. Nicorandil's (NIC) cardioprotective effect was caused by selective activation of the mitochondrial ATP-sensitive K+ channel (mitoKATP) and nitric oxide (NO) donor activity. These will lead to cardiac muscle relaxation and decrease reactive oxygen species and cell death. They also maintain calcium homeostasis and prevent high intracellular calcium levels, which can cause cellular malfunction and apoptosis.

Available studies show promising results for NIC in patients with heart failure. Preclinical studies suggested that NIC may also have a protective effect against DOX-induced cardiotoxicity by avoiding mitochondrial dysfunction without affecting the antitumor activity of DOX. Further clinical studies are needed to confirm the protective effect of NIC against DOX-induced cardiotoxicity.