Pharmacokinetics (PK) of Tiragolumab in First-in-Human Study in Patients with Mixed Solid Tumors (GO30103).

Abstract

Tiragolumab is a first-in-class, fully human IgG1/kappa anti-TIGIT monoclonal antibody that blocks the binding of TIGIT to CD155 (the poliovirus receptor). We summarize the pharmacokinetics (PK) data from the phase1a/1b GO30103 study of Q3W (every 3weeks) sequential dosing of tiragolumab (2, 8, 30, 100, 400, 600, or 1200mg) followed by atezolizumab (1200mg), Q4W (every 4weeks) sequential dosing (tiragolumab 840mg followed by atezolizumab 1680mg), and Q4W co-infusion (tiragolumab 840mg plus atezolizumab 1680mg). Serum samples were collected at multiple time points following tiragolumab and atezolizumab intravenous infusion in patients with solid tumors for PK and immunogenicity assessment. The serum PK profile of tiragolumab appeared to be biphasic, with a rapid distribution phase followed by a slower elimination phase when administered alone or in combination with atezolizumab. In phase1a, across doses of tiragolumab ranging from 2 to 1200mg (cycle1), the geometric mean (GM), coefficient of variation (CV%), serum tiragolumab Cmax ranged from 0.682 to 270µg/mL (18.6% to 36.5%) and Cmin ranged from 0.0125 to 75.3µg/mL (0.0% to 24.2%). The GM systemic exposure (area under the plasma drug concentration-time curve, AUC0-21) ranged from 310 to 2670µgday/mL (20.5% to 27.0%); interindividual variability in AUC0-21 ranged from 20.5% to 43.9%. Tiragolumab exposure increased in an approximately dose-proportional manner when administered alone or with atezolizumab at doses ≥100mg. Postbaseline, 4/207 patients (1.9%) were positive for treatment-emergent antidrug antibodies (ADA) against tiragolumab, each at a single time point. Tiragolumab combined with atezolizumab demonstrated desirable PK properties, with no drug-drug interactions or immunogenicity liability. There were no meaningful differences in tiragolumab or atezolizumab exposure between the Q4W co-infusion and sequential dosing cohorts. ClinicalTrials.gov: NCT02794571 (date of registration June 6, 2016).