INDUCE-1: A phase I open-label study of GSK3359609, an ICOS agonist antibody, administered alone and in combination with pembrolizumab in patients with advanced solid tumors.

Abstract

TPS3113 Background: Inducible T cell Co-Stimulator (ICOS), a member of the CD28/B7/CTLA-4 receptor superfamily expressed on T cells after engagement with cognate antigen and activation, provides a co-stimulatory signal augmenting T cell proliferation, survival and cytokine production. GSK3359609 is a humanized IgG4 antibody selected for its potent agonist activity against human ICOS. The unique mechanistic profile of an ICOS agonist antibody, such as GSK3359609, offers an opportunity to investigate the antitumor potential of targeting a T cell co-stimulator alone and in combination with other cancer immunotherapies such as pembrolizumab. Methods: INDUCE-1 is a first- in-human study evaluating safety, pharmacokinetics, pharmacodynamics, immunogenicity, and preliminary antitumor activity of GSK3359609 administered as an intravenous (IV) infusion once every 3 weeks (Q3W) alone (Part 1) and in combination with 200 mg pembrolizumab (Q3W IV infusion) or other immunotherapy (Part 2) in approximately 304 adult patients. In dose escalation, eligible patients are required to have selected relapsed/refractory solid tumors. Primary objective is to determine safety, tolerability, and maximum tolerated or administered dose. Modified toxicity probability interval method will inform dose escalation decisions (minimum 3 patients per dose level [DL]). In expansion, cohorts may be defined by factors such as tumor histology, biomarker features, or prior treatment. More than one GSK3359609 DL may be evaluated in an expansion cohort by random assignment. Blood immunophenotyping is monitored in all patients; tumor biopsies (before and on-treatment) are optional in escalation and required in expansion to provide biomarker data that may inform on optimal dose selection as well as mechanistic understanding of GSK3359609. Efficacy measures are every 9 weeks and are according to immune-related RECIST. As of 7 Feb 2017, the first 3 monotherapy DL cohorts completed without dose limiting toxicities; DL 4 enrollment is ongoing. Study is funded by GlaxoSmithKline and is in collaboration with Merck & Co., Inc. Clinical trial information: NCT02723955.