Abstract
Cyclin dependent kinases 4/6 (CDK4/6) inhibitors gained an essential role in the treatment of metastatic breast cancer. Nevertheless, data regarding their use in combination with radiotherapy are still scarce. We performed a retrospective preliminary analysis of breast cancer patients treated at our Center with palliative radiation therapy and concurrent CDK4/6 inhibitors. Toxicities were measured according to CTCAE 4.0, local response according to RECIST 1.1 or PERCIST 1.0 and pain control using verbal numeric scale. 18 patients (32 treated sites) were identified; 50% received palbociclib, 33.3% ribociclib and 16.7% abemacliclib. Acute non-hematologic toxicity was fair, with the only exception of a patient who developed G3 ileitis. During 3 months following RT, 61.1% of patients developed G 3–4 neutropenia; nevertheless no patient required permanent suspension of treatment. Pain control was complete in 88.2% of patients three months after radiotherapy; 94.4% of patients achieved and maintained local control of disease. Radiotherapy concomitant to CDK4/6 inhibitors is feasible and characterized by a fair toxicity profile, with isolated episodes of high-grade reversible intestinal toxicity. Rate of G 3–4 neutropenia was comparable with that measured for CDK4/6 inhibitors alone. Promising results were reported in terms of pain relief and local control of disease.
Highlights
Cyclin dependent kinases 4/6 (CDK4/6) inhibitors gained an essential role in the treatment of metastatic breast cancer
We performed a retrospective preliminary analysis of breast cancer patients treated at our Center with palliative radiation therapy to bone lesions and concurrent CDK4/6 inhibitors to assess the possible pitfalls of this combination
Patients who were treated with CDK4/6 inhibitors concomitantly with palliative radiotherapy were included in this analysis: the maximum interval allowed between last drug administration and radiotherapy was 2 half lives
Summary
Cyclin dependent kinases 4/6 (CDK4/6) inhibitors gained an essential role in the treatment of metastatic breast cancer. Data regarding their use in combination with radiotherapy are still scarce. We performed a retrospective preliminary analysis of breast cancer patients treated at our Center with palliative radiation therapy and concurrent CDK4/6 inhibitors. After different phase III trials[2,3,4,5,6,7] reporting significant improvements in response rate and progression free survival, palbociclib was the first CDK4/6 inhibitor authorized by European Medicines Agency in November 2016, followed by ribociclib in August 2017 and abemaciclib in September 2018. We performed a retrospective preliminary analysis of breast cancer patients treated at our Center with palliative radiation therapy to bone lesions and concurrent CDK4/6 inhibitors to assess the possible pitfalls of this combination
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