Background Palbociclib was commercialised in November 2017, for the treatment of hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative locally advanced or metastatic breast cancer in combination with an aromatase inhibitor or fulvestrant (in women who had received prior endocrine therapy).
Most common adverse events (AE) described in clinical trials (CT) were: haematological (neutropaenia (80.6%), leucopaenia (45.2%) and anaemia (27.6%)), and no-haematological, above all infections (54.7%). Neutropaenia was the most common AE, experienced in grade (G) 3 or 4 in 55.3% and 10.1% of patients, respectively. Median time for the first neutropaenia episode was 15 days, with a median duration of 7 days.
Purpose To evaluate the safety of palbociclib in real-world clinical practice and compare it with the results of CT.
Material and methods Prospective observational analysis (February to October 2018) on patients treated with palbociclib, in a regional hospital. Patients’ demographics and treatment evolution related to toxicity were analysed. Toxicity grade was classified by CTCAE V5.0. In each visit, the pharmacist revised physician’s prescription according to patient’s analysis results and made recommendations.
Results Nine women (average age of 56) with metastatic breast cancer HR-positive/HER2-negative were included. Five patients had been previously treated: hormonal therapy (3/9), chemotherapy (1/9) or both (1/9). According to prior treatments, five received palbociclib in combination with an aromatase inhibitor and four with fulvestrant. The median number of cycles received per patient was 4.5 (3–7). All presented neutropaenia in G3 (78%) or G1–2 (22%), experienced it after the first 15 days of treatment and although recovered, reappeared in ulterior cycles, leading to various discontinuations in seven patients (delays or interruptions of 7–14 days). Sixty-six per cent required dose reductions down to 100 or 75 mg, but no one had to stop treatment. Other AE with an incidence <24% were: rash and stomatitis G2, asthaenia, diarrhoea, leucopaenia and anaemia G1. No infections were reported.
Conclusion In clinical practice, the proportion of patients affected by neutropaenia was higher than in CT, with a 23% more incidence of G3. Close monitoring contributed to managing neutropaenia and preventing ulterior infections. In the future, it would be interesting to evaluate if discontinuations or dose reductions of palbociclib affect its efficacy.
References and/or acknowledgements No conflict of interest.