Relationship of T- and B-cell kinetics to clinical response in patients with relapsed/refractory non-Hodgkin lymphoma treated with blinatumomab.

Blinatumomab is a first-in-class immunotherapy based on the bispecific T-cell engager (BiTE®) immune-oncology platform, which redirects CD3 T cells to kill CD19 target cells. The objective of this analysis was to describe the correlation between B- and T-cell kinetics and response to blinatumomab in patients with relapsed or refractory (r/r) non-Hodgkin lymphoma (NHL). The clinical efficacy of treatment with blinatumomab in patients with r/r NHL was recently investigated in a phase 1 dose-escalation and expansion trial (NCT00274742) wherein 76 patients received blinatumomab by continuous intravenous infusion at various doses (0.5-90 μg/m/day). B-Cell depletion and expansion of CD3, CD4, and CD8 T cells was analyzed in patients stratified per clinical response (complete response [CR], n = 16; partial response [PR], stable disease [SD], or progressive disease [PD], n = 54) for at least 4 weeks (additional 4 weeks after clinical benefit) from the date of administration of blinatumomab until dose-limiting toxicity or PD. B-cell depletion kinetics were faster in patients who had a CR than in patients who did not have a complete response (PR, SD, or PD). T-cell expansion (T-cell counts exceeding the baseline level on day 22) was more pronounced in patients with CR than in patients without CR. T-cell expansion in patients with CR correlated with increased T-cell counts of both CD4 and CD8 T cells compared with patients without CR. Patients with r/r NHL who achieved a CR had faster B-cell depletion and increased expansion of CD3, CD4, and CD8 T cells than patients who did not achieve a CR.