Are there arguments for CDK4/6 inhibitors in visceral crisis in metastatic luminal breast cancer? Review of recent data and presentation of the clinical case

Breast cancer (BC) is the most common malignant tumour and the leading cause of cancer death in women worldwide [1, 2]. Significant progress has been made in the treatment of this disease over the last decade [3], largely due to the introduction of new drug treatment options, of which CDK4/6 inhibitors are one of the most important. CDK4/6 inhibitors in combination with hormonal therapy (aromatase inhibitors, fulvestrant) have shown in a number of trials a convincing increase in progression-free survival, objective response rate [4–12] and in some cases — an advantage in overall survival compared to hormonal therapy as monotherapy [6, 8, 11, 12], making the combination of CDK4/6 and hormonal therapy the unquestioned standard in first-line treatment of metastatic breast cancer [6, 8, 11–However, for a long time the possibility of using CDK4/6 inhibitors in the first-line setting of visceral crisis and aggressive disease was controversial and not considered an acceptable treatment option because of the lack of prospective data supporting the use of CDK4/6 inhibitors in the described clinical setting and their advantages over chemotherapy, which seemed to be an alternative treatment option. The following case describes the outcome of treatment with ribociclib and anastrozole in a patient with metastatic luminal breast cancer complicated by visceral crisis.