Cytheris SA announced recently that it has begun enrolling patients in INSPIRE 2. INSPIRE 2 is a Phase IIa clinical program evaluating Cytheris's investigative immune modulator, recombinant human interleukin-7 (CYT107), in the treatment of chronically infected HIV-1 patients classified as immunological non-responders after at least 12 months of highly active anti-retroviral therapy (HAART). The Phase IIa study is designed to evaluate the biological activity and pharmacokinetic (PK) profile of CYT107 at a dose of 20 microgram/kg/week in patients with CD4 counts of 101–400 cells/mL.
‘In most HIV patients, the first year of HAART therapy effectively suppresses viral replication but does not result in restoration and maintenance of CD4 T-cell counts above 500 cells/mm3, the threshold accepted as indicative of sufficient immune reconstitution in this patient population’, said Michel Morre, President and CEO of Cytheris. ‘In fact, some 30 percent of these patients will never achieve the 500 cells/mm3 level even after years of HAART treatment.’
The risk of disease progression or death in patients who remain below the 500 cells/mm3 level is significantly higher than in patients who achieve an optimal T-cell restoration. INSPIRE 2 is being launched to confirm the ability of CYT107 to trigger and support immune reconstitution in these patients, as documented in the first INSPIRE study.
CYT107 induces a dose dependent and sustained increase of CD4 T-cells, with many patients achieving CD4 counts >500 cells/mm3. The median CD4 and CD8 T-cell increases per mm3 over baseline, from 240 to 563 (135%) and from 659 to 1210 (65%), respectively, at the 20mcg/kg dose, suggest the potential of CYT107 to play a part in HIV therapy and represent part of the rationale for initiating the INSPIRE 2 study to further explore the immunological properties of CYT107.
INSPIRE 2 is an open-label, multicenter study of subcutaneous intermittent recombinant interleukin-7 (CYT107) in chronically infected HIV patients with CD4 T-lymphocyte counts between 101 and 400 cells/mm3 and plasma HIV RNA <50 copies/mL after at least 12 months of HAART.
The primary objective of the study is to determine in detail the biological activity and PK profile of CYT107 (20 microgram/kg/week) during a 12-week study period with a follow up period of up to one year, in an HIV-infected cohort with CD4 counts of 101–400 cells/mL. The dose of 20 microgram/Kg/week that will be evaluated in this study has shown a good safety profile and biological activity in the first INSPIRE study (CLI-107-06) conducted in a similar population.
Recombinant human interleukin-7 (CYT107) is a crucial immune modulator for immune T-cell recovery and enhancement. As a growth factor and cytokine physiologically produced by marrow or thymic stromal cells and other epithelia, IL-7 has a crucial and, at some steps, a non-redundant stimulating effect on T lymphocyte development, notably on thymopoïesis and, downstream from the thymus, on homeostatic expansion of peripheral T-cells.