Phase I study of NT-I7, a long-acting interleukin-7, in severe treatment-related lymphopenia following standard radiation and temozolomide for high-grade glioma

BACKGROUND: High-grade gliomas (HGG) have a poor prognosis despite aggressive treatment. Severe, persistent lymphopenia occurring in HGG patients after concurrent chemoradiation is associated with worse survival. NT-I7, a long-acting interleukin-7 analog, has been shown to increase CD4 and CD8 counts in healthy, septic, and HIV-positive adults. This multi-institutional, NCI-funded dose-escalation trial is the first to evaluate NT-I7 safety and activity in HGG patients with severe treatment-related lymphopenia (TRL) and the effect of co-administered glucocorticoids. METHODS: Eligible HGG patients had CD4 counts <300 cells/mm(3) after 5 weeks of standard chemoradiation and were receiving either ≤0.75 or ≥4 mg/day of dexamethasone. Patients received a single intramuscular dose of NT-I7 (60 or 360 µg/kg) post-chemoradiation, followed by safety evaluation and multi-parameter, longitudinal monitoring of lymphocyte populations and immunologic function. RESULTS: NT-I7 was well tolerated in all 12 patients (median age 64; median CD4 count 161 cells/mm³) before the study closed prematurely. Absolute lymphocyte counts doubled in 83% (10/12; 95% CI: 51.6%-97.9%) of patients, and CD4 counts doubled in 42% (5/12; 95% CI: 15.2%-72.3%) of patients. Glucocorticoid use did not significantly affect CD4 or lymphocyte increases. Correlative immune profiling revealed increased Ki67 expression in CD4 (P†<†.005) and CD8 (P†<†.05) after one week, along with the expansion of CD4 and CD8 T-cell subsets and CD56†+†natural killer cells. CONCLUSIONS: NT-I7 is well tolerated and effectively increases lymphocyte and CD4 counts in severe TRL patients, regardless of glucocorticoid use, suggesting its potential to mitigate TRL and improve outcomes in HGG.