Phase I study of the safety and clinical activity of the interleukin-8 inhibitor AMY109 combined with atezolizumab in patients with advanced solid cancers.

BACKGROUND

Immunosuppressive conditions within the tumor microenvironment (TME) can allow tumors to evade the immune system, including by hampering programmed death ligand 1 (PD-L1) inhibitor activity. Interleukin (IL)-8 contributes to immunosuppression and fibrosis in the TME. AMY109, a humanized anti-IL-8 monoclonal antibody, reduced fibrosis and decreased immunosuppressive cells in tumor tissue in animals. Combining AMY109 with atezolizumab (anti-PD-L1 antibody) may enhance its antitumor effects by making the TME more favorable to PD-L1 inhibition.

METHODS

This multicenter, open-label, dose-escalation study evaluated the safety, pharmacokinetics, and clinical activity of AMY109 plus atezolizumab in patients with previously treated advanced solid tumors and Eastern Cooperative Oncology Group performance status 0 or 1. Patients received AMY109 (2-45 mg/kg) plus atezolizumab (1200 mg) intravenously every 3 weeks in part 1, and AMY109 (15-45 mg/kg) plus atezolizumab (1200 mg) in part 2. Primary endpoints were the dose-limiting toxicity (DLT), safety, and pharmacokinetics of AMY109 and atezolizumab in Part 1, and safety and antitumor activity per investigator-assessed Response Evaluation Criteria in Solid Tumors 1.1 in part 2. Exploratory analyses of peripheral and tumor biomarker were conducted.

RESULTS

Overall, 38 patients (18 in part 1 and 20 in part 2) were enrolled. Part 1 showed no DLTs and a dose-proportional increase in AMY109 exposure over 2-45 mg/kg, with no apparent change in mean atezolizumab serum concentrations across AMY109 dosing. Plasma IL-8 concentration accumulation was seen in all dose cohorts after AMY109 initiation. Grade 1-3 treatment-related adverse events (AEs) occurred in 21 of 38 patients (55%). Treatment-related serious AEs occurred in two patients (5%). No AEs led to treatment withdrawal. Partial responses (PRs) occurred in 2 of 38 patients; the confirmed objective response rate was 5%. These patients had uterocervical and pancreatic cancer, respectively, and had been treated for >500 days at the cut-off date: one had received 45 mg/kg of AMY109 throughout, and the other received 30 mg/kg of AMY109 until cycle 5, then 45 mg/kg thereafter.

CONCLUSIONS

With no DLTs, AMY109 plus atezolizumab was well tolerated in patients with advanced solid tumors, with no new safety signals. AMY109 showed a dose-proportional increase in exposure. The PRs in two patients were durable.