Dr Politikos on the Immune Reconstitution Profiles of Orca-T and CD34 Allograft Recipients in Hematologic Malignancies

“[These findings] highlight unique biology in terms of immune reconstitution and may also explain the benefit in terms of lower infection rates in the patients who received Orca-T.”

Ioannis Politikos, MD, assistant attending physician, Memorial Sloan Kettering Cancer Center, discussed findings from a cross-sectional study that compared the immune reconstitution profiles of Orca-T with those from CD34 allograft recipients in patients with hematologic malignancies.

During the 51st Annual EBMT Meeting, Politikos presented data from the study which demonstrated that the rate of Epstein-Barr virus (EBV) reactivation was 2.3% among patients treated with Orca-T (n = 86) compared with 25.4% in those who received CD34 allografts (n = 179 P < .001). The CMV reactivation rates were 1.2% vs 25.6%, respectively (P < .001). The rates of EBV and/or CMV reactivation were 3.5% compared with 45.9%, respectively (P < .001).

Patients who received Orca-T also experienced early T-cell reconstitution, occurring as early as 7 days post-infusion, Politikos said. Comparatively, the CD34-selected patients had earlier recovery of B cells and natural killer cells, he added. These findings in the CD34 group may account for the higher incidence of EBV infections and protracted EBV infections in this cohort, Politikos noted.

Patients who received CD34 allografts experienced faster neutrophil and platelet engraftment. The median neutrophil engraftment time was 10 days (range, 10-11) in the CD34 arm compared with 13 days (range, 12-14) in the Orca-T. In terms of platelet engraftment, the median times were 16 days (range, 16-17) vs 18.5 days (range, 17-19), respectively.

At day 28 post-transplant, the median neutrophil counts were 2.5 (range, 1.8-3.8) in the Orca-T arm compared with 3.1 (range, 2.2-4.0) in the CD34 arm. At days 56, 100, 180, and 365, these respective median counts were 2.5 (range, 1.8-3.4) vs 3.0 (range, 2.2-3.8), 2.8 (range, 2.1-3.9) vs 2.8 (range, 2.2-3.8), 2.6 (range, 2.0-3.7) vs 2.9 (range, 2.1-3.9), and 2.9 (range, 2.2-3.9) vs 2.8 (range, 1.9-3.8). The respective median monocyte counts at days 56, 100, 180, and 365, were 0.7 (range, 0.5-0.9) vs 0.7 (range, 0.5-1.1), 0.4 (range, 0.4-0.6) vs 0.5 (range, 0.3-0.6), 0.4 (range, 0.3-0.6) vs 0.5 (range, 0.4-0.6), 0.4 (range, 0.3-0.6) vs 0.4 (range, 0.3-0.6), and 0.4 (range, 0.3-0.6) vs 0.5 (range, 0.3-0.6).