Integrating radiation therapy with CDK4/6 inhibitors for breast cancer: A systematic review and meta-analysis of toxicity.

Abstract

e13075 Background: Over the past years, the treatment landscape of breast cancer (BC) has significantly evolved. Several new anticancer agents entered clinical use. Among them CDK4/6i have revolutionised both curative and advanced BC scenarios. The availability of new drugs raises the crucial question on how to integrate them with local and regional treatments. Strong levels of evidence on the safety profile of CDK4/6i in combination with different RT techniques or schedules are currently missing. We aim to systematically review and summarise the published data on the safety profile of palliative and ablative RT combined with CDK4/6i in early and metastatic BC settings. Methods: A literature search (PUBMED/MedLine, Embase, and Cochrane databases) was conducted to identify original studies on the safety profile of the combination of CDK4/6i with RT. This systematic review and meta-analysis project is part of the ESTRO Guidelines Committee consensus recommendations on integration of RT with targeted treatments for breast cancer, an initiative developed by a multidisciplinary Core Group and Expert Panel of medical, clinical, radiation oncologists, preclinical specialists, and patient advocates. Results: Eleven articles finally met all eligible criteria and were included in the meta-analysis. Data could not be collected in the adjuvant setting due to lack of data in the current literature. Pooling data of the included studies show a moderate incidence of hematological toxicities grade 3+ (21.0 %) and a very low-grade 3+ non-hematological toxicity were observed. Conclusions: The safety profile of CK4/6i and RT combination is acceptable. However, international consensus guidelines regarding the safety issue of CDK4/6i and RT combination for breast cancer are warranted.