1. Early treatment-related neutropenia predicts response to palbociclib
- Author
-
McAndrew, Nicholas P, Dickson, Mark A, Clark, Amy S, Troxel, Andrea B, O’Hara, Mark H, Colameco, Christopher, Gallager, Maryann, Gramlich, Kristi, Zafman, Kelly, Vaughn, David, Schwartz, Gary K, O’Dwyer, Peter J, and DeMichele, Angela
- Subjects
Biomedical and Clinical Sciences ,Clinical Sciences ,Oncology and Carcinogenesis ,Cancer ,Clinical Research ,Breast Cancer ,Clinical Trials and Supportive Activities ,Adolescent ,Adult ,Aged ,Aged ,80 and over ,Cyclin-Dependent Kinase 4 ,Cyclin-Dependent Kinase 6 ,Female ,Humans ,Male ,Middle Aged ,Neoplasms ,Neutropenia ,Piperazines ,Proportional Hazards Models ,Protein Kinase Inhibitors ,Pyridines ,Young Adult ,Public Health and Health Services ,Oncology & Carcinogenesis ,Oncology and carcinogenesis - Abstract
BackgroundPalbociclib is highly active in oestrogen-receptor positive (ER+) metastatic breast cancer, but neutropenia is dose limiting. The goal of this study was to determine whether early neutropenia is associated with disease response to single-agent palbociclib.MethodsBlood count and disease-response data were analysed from two Phase 2 clinical trials at different institutions using single-agent palbociclib: advanced solid tumours positive for retinoblastoma protein and advanced liposarcoma. The primary endpoint was PFS. The primary exposure variable was the nadir absolute neutrophil count (ANC) during the first two cycles of treatment.ResultsOne hundred and ninety-six patients (61 breast, 135 non-breast) were evaluated between the two trials. Development of any grade neutropenia was significantly associated with longer median PFS in both the breast cancer (HR 0.29, 95% CI 0.11-0.74, p = 0.010) and non-breast cancer (HR 0.57, 95% CI 0.38-0.85, p = 0.006) cohorts. Grade 3-4 neutropenia was significantly associated with prolonged PFS in the non-breast cohort (HR 0.57, 95% CI 0.38-0.85, p = 0.006) but not in the breast cohort (HR 0.87, 95% CI 0.51-1.47, p = 0.596). Multivariate analysis yielded similar results.ConclusionsTreatment-related neutropenia in the first two cycles was significantly and independently associated with prolonged PFS, suggesting that neutropenia may be a useful pharmacodynamic marker to guide individualised palbociclib dosing.Clinical trials registration informationBasket Trial: NCT01037790; Sarcoma Trial: NCT01209598.
- Published
- 2020