Administration of Mogamulizumab before Allogeneic Hematopoietic Cell Transplantation Against ATLL Might Increase Risks of Acute Gvhd and Non-Relapse Mortality

Background: Mogamulizumab (anti-CCR4 monoclonal antibody; MOG) is effective as a treatment for adult T-cell leukemia/lymphoma (ATLL), but the influence of MOG administration before allogeneic hematopoietic cell transplantation (allo-HCT) on transplant outcomes is not clear. We compared transplant outcomes in patients who received MOG before allo-HCT with outcomes in those who did not. Methods: This study included 88 patients with ATLL who underwent their first allo-HCT between January 2001 and July 2014 at the National Cancer Center Hospital. Three patients who received cord blood transplantation were excluded. Results: MOG was used in 11 patients before allo-HCT. The median time from the last MOG administration to allo-HCT was 46 days (range, 17-198 days), and the median number of administration was 5 times (range, 1-8 times). The median follow-up period among survivors was 1505 days after HCT (range, 100-4393 days) in all patients, and the MOG group had a shorter follow-up period (median 249 days, range 101-284 days). More patients received tacrolimus-based GVHD prophylaxis in MOG group than in non-MOG group (n=10 (91%) vs. n=42 (55%), P=0.024). There was no significant difference in other patient- and transplant-related characteristics. The incidences of grade II-IV and grade III-IV acute GVHD were 82% and 36%, respectively, in MOG group and 46% and 17%, respectively, in non-MOG group. The incidence of grade II-IV acute GVHD in MOG group was significantly higher than that in non-MOG group (P=0.003). The cumulative incidence rate of non-relapse mortality (NRM) and the overall survival (OS) rate at 6 months after allo-HCT were 58.2% and 31.8%, respectively, in MOG group and 13.1% and 76.5%, respectively, in non-MOG group. Patients in MOG group had significantly worse outcomes than those in non-MOG group (NRM, P=0.001; OS, P=0.006). In MOG group, main causes of NRM included infection after acute GVHD (n=3) and multiple organ failure (n=2). In multivariate analyses, MOG administration before HCT was a risk factor for grade II-IV acute GVHD (HR 3.57, 95%CI 1.62-7.78, P=0.002) and NRM (HR 4.58, 95%CI 1.78-11.82, P=0.002). Conclusion: Despite the small sample size and short observation period, our data suggested that the administration of MOG before allo-HCT could increase risks of acute GVHD and NRM. Appropriate management of acute GVHD including prophylaxis and treatment should be investigated for ATLL patients who received MOG before allo-HCT.