PATIENTS AND METHODS
The primary objectives of this Phase I study (PBTC-042, NCT02255461)
were to determine the maximum tolerated dose (MTD)/recommended Phase II
dose (RP2D), describe toxicities, and characterize palbociclib
pharmacokinetics. Secondary objectives were to record preliminary
evidence of palbociclib antitumor effect, evaluate CDK4/6, cyclin D1-3,
Ink4a-ARF copy-number variations, explore potential relationships
between palbociclib pharmacokinetics and pharmacodynamics, and relate
pharmacogenetic polymorphisms to palbociclib pharmacokinetics.