hIL-7-hyFc, A Long-Acting IL-7, Increased Absolute Lymphocyte Count in Healthy Subjects.

A low lymphocyte count puts immune-compromised patients at risk of mortality. hIL-7-hyFc is a homodimeric interleukin-7 (IL-7), a potent T-cell amplifier, fused to the hybridizing IgD/IgG4 immunoglobulin domain. We performed a randomized, double-blind, placebo-controlled, dose-escalation, phase I study to assess the pharmacokinetic, pharmacodynamic, safety, tolerability, and immunogenicity profiles of hIL-7-hyFc administered s.c. and i.m. to healthy volunteers. Thirty subjects randomly received hIL-7-hyFc or its matching placebo in an 8:2 ratio at 20, 60 µg/kg s.c., or 60 µg/kg i.m. The hIL-7-hyFc was slowly absorbed and its terminal half-life was 63.26 hours after i.m. administration. The hIL-7-hyFc increased absolute lymphocyte count, mostly in T-cells, which peaked 3 weeks after administration and then lasted for several additional weeks. The hIL-7-hyFc was well-tolerated after a single s.c. and i.m. administration. Injection site reaction was the most common treatment-emergent adverse event, which resolved spontaneously without treatment. The hIL-7-hyFc can be developed into a beneficial treatment option for patients with compromised T-cell immunity. This trial was registered at www.clinicaltrials.gov as #NCT02860715.