Treatment Regimen, Drug Administration, and Dose Escalation
Palbociclib was supplied by Pfizer as 75, 100, and 125 mg capsules, taken orally once a day for 21 days followed by a 7-day rest. One course was equivalent to 28 days. Patients were encouraged to take palbociclib with food at the same time each day. The pediatric equivalent dosage of the adult MTD (125 mg daily on this same schedule)6,7was approximately 75 mg/m2. The starting dosage for Stratum I was 50 mg/m2 with planned dose escalations to 75 mg/m2 and 95 mg/m2. The planned starting dosage for Stratum II was one dosage level below the MTD for Stratum I. Dosage escalation was governed by the Rolling-6 statistical design separately in each of the two strata.16 Therapy was allowed to continue for up to two years (26 courses) in the absence of disease progression or unacceptable toxicity.