Bar M, et al. - A multicenter prospective Phase II study was planned to examine the safety and efficacy of pentostatin followed by donor lymphocyte infusion (DLI) in patients with low donor T-cell chimerism after allogeneic hematopoietic cell transplantation (HCT). Findings suggested that pentostatin/DLI had acceptable toxicity. It seemed increasing low donor CD3 chimerism after HCT but had no impact on mortality.

• This study enrolled 36 patients with low donor blood CD3 chimerism.
• A total of 41 DLIs were offered to 35 patients following a dose of pentostatin, and one patient was administered pentostatin only.
• In this study, median donor CD3 chimerism prompting the initiation of pentostatin/DLI was 28 (5 to 47)%.
• In 16 patients (44.4%), responses (defined by increases in donor CD3 chimerism ≥10% maintained to day 56 post-DLI) were observed with a median rise in CD3 donor chimerism to 64 (48 to 100)%.
• Among the 21 patients who received first treatment within 100 days after transplant, a trend for better responses (57% response rate) was observed compared to the 15 patients who received first treatment more than 100 days after HCT (27% response rate) (p=0.07).
• At a median of 10 (0 to 83) days after DLI, grade II-IV acute GVHD developed in14 patients (39%).
• Extensive chronic GVHD developed in ten patients (28%).
• After DLI, new grade 4 cytopenias developed in 17 patients (47%).
• Findings revealed no difference in relapse between non-responders and responders.
• Findings revealed death of 28 patients (78%), these were mostly (n= 21) due to relapse.
• At a median 60 (range 21 to 132) months after DLI, five of the 16 responders (31%) were alive, all disease-free.
• At median of 47 (range 16 to 100) months after DLI, 6 of the 20 non-responders (30%) were alive, 3 in complete remission.