A Single-arm, Dose-escalation Trial of Long-acting Recombinant Human IL-7 (NT-I7, Efineptakin Alfa) for Idiopathic CD4 Lymphopenia

Structural Formula: NT-I7 is a fusion protein comprising human IL-7 fused to the human IgD hinge region. This in turn is fused to the N-terminal region of CH2 from IgD and two key regions of the antibody IgG4: C-terminal region of CH2 and the entire CH3 region. NT-I7 will be administered by IM injection once every 12 weeks for a total of 3 doses, with the final dose at week 24. In the absence of treatment delays due to AEs, a treatment course of 24 weeks will be pursued in all enrolled participants. The dose levels to be used in this study are 240, 480, and 720 microgram/kg. NT-I7 dosing will be determined using the weight recorded at the screening visit. The dose will be based on the participant s actual body weight, unless the participant has a BMI \>=30 kg/m2, in which case adjusted body weight will be used.