Exelixis initiates phase 1b trial of cabozanitinib, atezolizumab combination
Exelixis announced the initiation of the dose-escalation stage of a phase 1b trial of cabozantinib in combination with atezolizumab in patients with locally advanced or metastatic urothelial carcinoma or renal cell carcinoma. The primary objective is to determine the optimal dose and schedule of daily oral administration of cabozantinib when given in combination with atezolizumab to inform the trial's subsequent expansion stage. This multicenter phase 1b, open-label study is divided in two parts: a dose-escalation phase and an expansion cohort phase. The dose-escalation phase will enroll 9 to 36 patients with inoperable, locally advanced, metastatic or recurrent UC after prior platinum-based therapy or RCC with or without prior systemic therapy. The starting dose of cabozantinib will be 40 mg daily and may be increased to 60 mg daily or decreased to 20 mg daily. All patients will receive the standard atezolizumab dosing regimen. The secondary objectives of the dose-escalation stage are to evaluate the plasma pharmacokinetics of daily oral administration of cabozantinib when given in combination with atezolizumab and to assess safety of the combination therapy through the evaluation of incidence and severity of adverse events, including immune-related adverse events. Exploratory endpoints include the correlation of clinical outcome with immune cell, tumor cell and blood biomarker analyses. Once the recommended dose and schedule are determined, the trial will enroll four expansion cohorts, each with up to 30 patients, for a total of up to 120 patients with advanced or metastatic UC or RCC. The primary objective in the expansion stage of the trial is to determine the objective response rate in each cohort.