Dose-Escalation Study Of Palbociclib + Nab-Paclitaxel In mPDAC

The study has 2 parts: • Part A (Dose-Escalation Cohorts): Consecutive cohorts of patients will receive escalating doses of oral palbociclib in combination with intravenous nab-P in 28-day cycles, in order to estimate the MTD(s) of the combination. The starting doses will be 75 mg palbociclib, and 100 mg/m2 nab-P. The observation period for dose-limiting toxicities (DLTs) will be from Day 1 to Day 28. Pharmacokinetic (PK) and pharmacodynamic (PD) properties of palbociclib and nab-P will also be assessed. Up to approximately 30 patients will be enrolled. The criteria for dose escalation will be based on a modified toxicity probability interval (mTPI) method. • Part B \[MTD Expansion Cohort(s)\]: When the MTD(s) of palbociclib plus nab-P has been estimated with confidence, enrollment will proceed into 1 or 2 MTD expansion cohort(s) of up to 20 patients each at the MTD(s). The objective of the MTD expansion cohort(s) will be to provide additional information on safety, tolerability, biomarkers, PD activity, and PK/PD relationship for the combination regimen in order to determine the RP2D. The MTD expansion cohort(s) will only enroll patients who have not received previous treatment for their metastatic disease in order to evaluate preliminary activity of the combination in the target patient population. All patients (in Part A and B) will receive nab-P intravenously once weekly for 3 weeks out of each 28-day cycle. Palbociclib oral dosing will be once daily on Days 1-21 of each 28-day cycle. To allow for PK evaluation of nab-P administered alone, nab-P will be administered on Day -2 for Cycle 1 only. Subsequent cycles will administer both nab-P and palbociclib on Day 1. Alternate dosing schedules for palbociclib may be explored based on emerging PK, PD, and safety data. Patients will be treated as long as they are clinically benefiting from investigational product without unacceptable toxicity, objective disease progression, or withdrawal of consent. A modified visit schedule will be implemented for patients who are on investigational product for more than 2 years.