Population Pharmacokinetic/Pharmacodynamic Modeling of Sunitinib by Dosing Schedule in Patients with Advanced Renal Cell Carcinoma or Gastrointestinal Stromal Tumor

BACKGROUND Sunitinib is a multi-targeted tyrosine kinase inhibitor used in the treatment of advanced renal cell carcinoma (RCC) and imatinib-resistant/intolerant gastrointestinal stromal tumors (GIST). METHODS A meta-analysis of 10 prospective clinical studies in advanced RCC and GIST was performed to support the development of pharmacokinetic (PK) and PK/pharmacodynamic (PD) models that account for the effects of important covariates. These models were used to make predictions with respect to the PK, safety, and efficacy of sunitinib when administered on the traditional 4-weeks-on/2-weeks-off schedule (Schedule 4/2) versus an alternative schedule of 2 weeks on/1 week off (Schedule 2/1). RESULTS The covariates found to have a significant effect on one or more of the PK or PD parameter studies included, age, sex, body weight, race, baseline Eastern Cooperative Oncology Group performance status, tumor type, and dosing schedule. The models predicted that, in both RCC and GIST patients, Schedule 2/1 would have comparable efficacy to Schedule 4/2, despite some differences in PK profiles. The models also predicted that, in both indications, sunitinib-related thrombocytopenia would be less severe when sunitinib was administered on Schedule 2/1 dosing compared with Schedule 4/2. CONCLUSION These findings support the use of sunitinib on Schedule 2/1 as a potential alternative to Schedule 4/2 because it allows for the management of toxicity without loss of efficacy.