Ribociclib plus letrozole and concomitant palliative radiotherapy for metastatic breast cancer.

Ribociclib is a CDK4-6 inhibitor recently approved by the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) as first-line treatment for metastatic breast cancer (MBC). The pivotal trial showed a significant improvement in progression-free survival when compared to endocrine therapy alone. However, having a challenging toxicity profile in comparison with exclusive endocrine therapy, safety may be a concern when combined to radiotherapy (RT) with palliative approach. There are no available published data regarding the combination of ribociclib and palliative RT. We reported our preliminary experience on the first five patients treated at the Radiation Oncology Unit of the Florence University (Florence, Italy) giving palliative RT concomitant to ribociclib plus letrozole as first-line treatment for MBC.