Exposure-toxicity associations
Associations were explored between palbociclib Cmax and AUC0-Tlast after single and repeated doses and hematologic toxicities occurring during course 1 that were at least possibly attributable to the drug. Toxicities included neutropenia, thrombocytopenia, lymphopenia, and leukopenia. Patients were classified into three categories (0/1/2) based on their highest toxicity grade reported for course 1 for each toxicity: 0 = no toxicity reported, 1 = grade 1 or 2, and 2 = grade 3 or 4. Ordinal logistic regression models were built for each hematological toxicity outcome, and explanatory pharmacokinetic variables were transformed by dividing by 100. Statistical significance was defined by a p-value P < 0.05.