First-in-human phase 1 dose-escalating trial of G305 in patients with advanced solid tumors expressing NY-ESO-1

Human tumor cells express antigens that serve as targets for the host cellular immune system. This phase 1 dose-escalating study was conducted to assess safety and tolerability of G305, a recombinant NY-ESO-1 protein vaccine mixed with glucopyranosyl lipid A (GLA), a synthetic TLR4 agonist adjuvant, in a stable emulsion (SE). Twelve patients with solid tumors expressing NY-ESO-1 were treated using a 3 + 3 design. The NY-ESO-1 dose was fixed at 250 µg, while GLA-SE was increased from 2 to 10 µg. Safety, immunogenicity, and clinical responses were assessed prior to, during, and at the end of therapy. G305 was safe and immunogenic at all doses. All related AEs were Grade 1 or 2, with injection site soreness as the most commonly reported event (100%). Overall, 75% of patients developed antibody response to NY-ESO-1, including six patients with increased antibody titer (≥ 4-fold rise) and three patients with seroconversion from negative (titer < 100) to positive (titer ≥ 100). CD4 T-cell responses were observed in 44.4% of patients; 33.3% were new responses and 1 was boosted (≥ 2-fold rise). Following treatment, 8 of 12 patients had stable disease for 3 months or more; at the end of 1 year, three patients had stable disease and nine patients were alive. G305 is a potent immunotherapeutic agent that can stimulate NY-ESO-1-specific antibody and T-cell responses. The vaccine was safe at all doses of GLA-SE (2–10 µg) and showed potential clinical benefit in this population of patients.