GX-I7, a long-acting IL-7, safely and effectively increased peripheral CD8/CD4 T cells and TILs in patients with locally advanced or metastatic solid tumours.

Background: GX-I7 (rhIL-7-hyFc, efineptakin alfa) is a hybrid Fc-fused long-acting interleukin-7 (IL-7) with the aim of correcting T-cell deficiency, thereby strengthening the immune response to fight against cancer. This Phase 1b, dose-escalation study was designed to assess the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of GX-I7 in patients with locally advanced or metastatic solid tumours.

Methods: This study, conducted in patients with advanced solid tumours at three hospitals in Korea, involved intramuscular GX-I7 administration across eight dose levels (60-1700 µg/kg) in 3- and 6-week cohorts. A dose-expansion phase at 720 and 1200 µg/kg further assessed GX-I7's safety and efficacy.

Results: Anti-tumour responses showed either stable disease (SD) or disease progression (PD). GX-I7 demonstrated dose-dependent increases in the maximum serum concentration (C) and area under the curve up to the last measurable concentration (AUC). In addition, a dose-dependent increase in circulating CD8/CD4 T cells was observed. In five patients who consented for biopsy, a statistically significant increase in tumour-infiltrating lymphocytes (TILs) followed GX-I7 treatment.

Discussion: Findings suggest GX-I7 is a safe T cell-amplifying agent with peripheral immune activation. Ongoing studies are exploring its ability to enhance immune responses in peripheral immune cells and tumour cells when combined with other anti-cancer agents.

Clinical Trial Registration: NCT03478995.