Baseline lymphopenia as prognostic factor in patients with metastatic breast cancer treated with palbociclib
George Emile, Sarah Penager, Christelle Lévy, Alison Johnson, Djelila Allouache, Justine Lequesne, Ioana Hrab, Carine Ségura, Adeline Morel, Katarina Gunzer, Audrey Faveyrial, François Cherifi, Angélique Da Silva
Abstract
Cyclin‑dependent‑kinase 4‑6 inhibitors (CDK4/6i) have improved the management of hormone receptor (HR)<sup>+</sup>/human epidermal growth factor receptor (HER)2‑ metastatic breast cancer (mBC). Currently, there are no valid prognostic factors for response to CDK4/6i. Baseline lymphopenia is reported as a prognostic factor in several types of cancer. The present retrospective study aimed to evaluate the effect of baseline absolute lymphocyte count (ALC) on response to palbociclib. Progression‑free survival (PFS) was the primary endpoint. Secondary endpoints were overall survival (OS), best response and safety. A total of 114 patients treated for mBC between 2016 and 2019 were included. Median baseline ALC was 1.4 g/l (range, 0.2‑4.3 g/l). A total of 65 (57%) and 49 (43%) patients had baseline ALC values of <1.5 and ≥1.5 g/l, respectively. Patients with baseline lymphopenia exhibited significantly shorter PFS (6 vs. 10 months; P=0.004) and OS (20 vs. 33 months; P=0.02). ALC <1.5 g/l independently predicted worse survival, as indicated by multivariate analysis (P=0.04; hazard ratio, 1.76; 95% confidence interval, 1.02‑3.02). Patients with baseline ALC <1.5 g/l had significantly less partial response (14 vs. 22%; P=0.016) and more disease progression (46 vs. 20%; P=0.016) than those with ALC ≥1.5 g/l. ALC is a strong and easy‑to‑use dosage with prognostic factor for patients with HR<sup>+</sup>/HER2<sup>‑</sup> mBC treated with palbociclib and endocrine therapy. Lymphopenia may also be a predictive factor of early progression. These data need to be verified in a larger prospective study.