Effects of ABO incompatibility in allogeneic hematopoietic stem cell transplantation.

INTRODUCTION: The impact of ABO mismatch on outcomes following allo-HSCT remains controversial. In this study, our aim is to define the effect of ABO mismatch on post-transplant outcomes, engraftment kinetics and complications in a large cohort. PATIENTS AND METHODS: We retrospectively identified 1000 patients who underwent allo-HSCT from either bone marrow or peripheral blood stem cells at our center between 1988 and 2016. P<0.05 was considered statistically significant. RESULTS: Five hundred and ninety (59%) patient-donor pairs were ABO matched, 164 (16.4%) were ABO major mismatched (MM), 191 (19.1%) were ABO minor MM, and 55 (5.5%) were ABO bi-directionally MM. ABO matched pairs were more common in transplants from related donors (P<0.001) and using bone marrow as a stem cell source (P<0.001). In minor ABO MM transplantations, mild delayed hemolytic reaction occurred more frequently compared to major and bidirectional ABO MM transplantations (47% vs 35% and 18%, P<0.001). Neutrophil engraftment was slightly delayed in ABO MM patient-donor pairs when compared ABO matched donor pairs according to median engraftment time in all group (167/410, 41% vs 204/590, 35%, P=0.046). Pure red cell aplasia was diagnosed in 6 patients (1%). Higher risk of death was shown in ABO MM transplants compared to ABO matched transplants in overall survival (OS) analysis (HR:1.201, 95% CI:1.004-1.437, P=0.045). The non-relapse mortality (P=0.546) and cumulative incidences of acute graft versus host disease (aGVHD) and chronic (c) GVHD were comparable between ABO MM and ABO matched patient-donor pairs (for aGVHD, P=0.235; for cGVHD, P=0.137). CONCLUSION: ABO MM transplants were associated with decreased OS and slightly delayed neutrophil engraftment. NRM and the risk of GVHD were not related to ABO incompatibility.

Nivolumab for relapsed or refractory Hodgkin lymphoma: real-life experience.

BACKGROUND: Reed-Sternberg cells of classical Hodgkin's lymphoma (cHL) are characterized by genetic alterations at the 9p24.1 locus, leading to over-expression of programmed death-ligand 1 and 2. In a phase 1b study, nivolumab, a PD-1-blocking antibody, produced a high response in patients with relapsed or refractory cHL, with an acceptable safety profile. PATIENTS AND METHODS: We present a retrospective analysis of 82 patients (median age: 30 years; range: 18-75) with relapsed/refractory HL treated with nivolumab in a named patient program from 24 centers throughout Turkey. The median follow-up was 7 months, and the patients had a median of 5 (2-11) previous lines of therapy. Fifty-seven (70%) and 63 (77%) had been treated by stem-cell transplantation and brentuximab vedotin, respectively. RESULTS: Among 75 patients evaluated after 12 weeks of nivolumab treatment, the objective response rate was 64%, with 16 complete responses (CR; 22%); after 16 weeks, it was 60%, with 16 (26%) patients achieving CR. Twenty patients underwent subsequent transplantation. Among 11 patients receiving allogeneic stem-cell transplantation, 5 had CR at the time of transplantation and are currently alive with ongoing response. At the time of analysis, 41 patients remained on nivolumab treatment. Among the patients who discontinued nivolumab, the main reason was disease progression (n = 19). The safety profile was acceptable, with only four patients requiring cessation of nivolumab due to serious adverse events (autoimmune encephalitis, pulmonary adverse event, and two cases of graft-versus-host disease aggravation). The 6-month overall and progression-free survival rates were 91.2% (95% confidence interval: 0.83-0.96) and 77.3% (0.66-0.85), respectively. Ten patients died during the follow-up; one of these was judged to be treatment-related. CONCLUSIONS: Nivolumab represents a novel option for patients with cHL refractory to brentuximab vedotin, and may serve as a bridge to transplantation; however, it may be associated with increased toxicity.