Donor specific anti-HLA antibodies in hematopoietic stem cell transplantation. Single Center prospective evaluation and desensitization strategies employed.

BACKGROUND: In the setting of mismatched-hematopoietic stem cells transplantation, the detection of antibodies directed against donor-specific HLA allele(s) or antigen(s) (DSA) represents a barrier for engraftment. It is thus necessary to plan an immunosuppressive strategy, or to select an alternative donor. This prospective study aimed at evaluating the efficacy of our strategy for testing DSAs and the efficacy of the desensitization strategy (DS) employed between November 2017 and November 2020. MATERIALS AND METHODS: The anti-HLA antibody search was performed using the Luminex bead assays (Lifecode ID and LSA I/II-Immucor) and expressed as mean fluorescence intensity (MFI >1,000 positive). If the patient had DSAs and no alternative donors, a DS was employed with rituximab (day -15), 2 single volume plasmaphereses (PP; days -9 and -8), intravenous immunoglobulins (day -7) and infusion of HLA selected platelets, if persistent DSAs were directed against class I HLA. DS was scheduled with or without PP, according to the DSA MFI (>1,000 or <5,000) and FCXM (flow cytometry crossmatch). RESULTS: Twenty-two out of 126 patients (17.46%) showed anti-HLA antibodies, 5 of them DSAs (3.97% of total); 3 patients underwent DS obtaining engraftment. Female gender (p=0.033) and a history of previous pregnancies or miscarriages (p=0.009) showed a statistically significant impact on alloimmunization. Factors associated with a delayed neutrophil engraftment were patient's female gender (p=0.039), stem cell source (p=0.025), and a high HSCT-specific comorbidity index (p=0.028). None of the analyzed variables, including the DSA detection, influenced engraftment. CONCLUSIONS: Our study confirms the importance to test DSAs in mismatched-hematopoietic stem cells transplantation The DS used proved successful in removing DSAs. Prospective multicenter studies are needed to better define and validate consensus strategies on DSA management in HSCT.

Positive HCMV DNAemia in stem cell recipients undergoing letermovir prophylaxis is expression of abortive infection.

Letermovir (LMV) inhibits HCMV replication by binding to components of the HCMV-terminase complex showing a potential role in prevention of HCMV-related complications in allogenic hematopoietic stem cell transplant recipients (allo-HSCTRs). However, little is known about breakthrough HCMV infection and the relevance of HCMV DNAemia during prophylaxis. We reported the results of a multicenter prospective study involving five Italian centers in the management of HCMV DNAemia in 75 adult HCMV-seropositive allo-HSCTRs undergoing LMV prophylaxis. The aim of the present study was to characterize the presence of real HCMV reactivation during LMV prophylaxis. Then, the presence of circulating infectious HCMV particles was determined by virus isolation and degradation of free-floating viral DNA. This report provides the first evidence that during LMV prophylaxis the clinical relevance of HCMV DNAemia should be critically considered.

Allogeneic stem cell transplantation in patients with atypical chronic myeloid leukaemia: a retrospective study from the Chronic Malignancies Working Party of the European Society for Blood and Marrow Transplantation.

Atypical chronic myeloid leukaemia (aCML) is an aggressive malignancy for which allogeneic haematopoietic stem cell transplantation (allo-HSCT) represents the only curative option. We describe transplant outcomes in 42 patients reported to the European Society for Blood and Marrow Transplantation (EBMT) registry who underwent allo-HSCT for aCML between 1997 and 2006. Median age was 46 years. Median time from diagnosis to transplant was 7 months. Disease status was first chronic phase in 69%. Donors were human leucocyte antigen (HLA)-identical siblings in 64% and matched unrelated (MUD) in 36%. A reduced intensity conditioning was employed in 24% of patients. T-cell depletion was applied in 87% and 26% of transplants from MUD and HLA-identical siblings, respectively. According to the EBMT risk-score, 45% of patients were 'low-risk', 31% 'intermediate-risk' and 24% 'high-risk'. Following allo-HSCT, 87% of patients achieved complete remission. At 5 years, relapse-free survival was 36% and non-relapse mortality (NRM) was 24%, while relapse occurred in 40%. Patient age and the EBMT score had an impact on overall survival. Relapse-free survival was higher in MUD than in HLA-identical sibling HSCT, with no difference in NRM. In conclusion, this study confirmed that allo-HSCT represents a valid strategy to achieve cure in a reasonable proportion of patients with aCML, with young patients with low EBMT risk score being the best candidates.

Can chronic myeloid leukaemia in children and adolescents be successfully treated without haematopoietic stem cell transplant? A single centre experience.

We analysed the long-term outcome of 35 children and adolescents (<20 years at diagnosis) with chronic myeloid leukaemia (CML) in chronic phase: 20 patients had received interferon-alpha and/or tyrosine kinase inhibitors (TKIs), and 15 underwent a haematopoietic stem cell transplant. The 10-year survival probabilities were similar in transplanted and non-transplanted patients (73·3% vs. 72·1%, respectively), whereas the survival probability was significantly lower in patients diagnosed before 1999 compared to those diagnosed afterwards (62·1% vs. 100%, P = 0·0384). The availability of TKIs and the standardized molecular monitoring have significantly improved treatment, management and outcome in children and adolescents with CML.

Impact of FLT3 internal tandem duplication on the outcome of related and unrelated hematopoietic transplantation for adult acute myeloid leukemia in first remission: a retrospective analysis.

PURPOSE: Patients with acute myeloid leukemia (AML) and FLT3/internal tandem duplication (FLT3/ITD) have poor prognosis if treated with chemotherapy only. Whether this alteration also affects outcome after allogeneic hematopoietic stem-cell transplantation (HSCT) remains uncertain. PATIENTS AND METHODS: We analyzed 206 patients who underwent HLA-identical sibling and matched unrelated HSCTs reported to the European Group for Blood and Marrow Transplantation with a diagnosis of AML with normal cytogenetics and data on FLT3/ITD (present: n = 120, 58%; absent: n = 86, 42%). Transplantations were performed in first complete remission (CR) after myeloablative conditioning. RESULTS: Compared with FLT3/ITD-negative patients, FLT3/ITD-positive patients had higher median leukocyte count at diagnosis (59 v 21 × 10(9)/L; P < .001) and shorter interval from CR to transplantation (87 v 99 days; P = .04). Other characteristics were similar in the two groups. At 2 years, relapse incidence (RI; ± standard deviation) was higher (30% ± 5% v 16% ± 5%; P = .006) and leukemia-free survival (LFS) lower (58% ± 5% v 71% ± 6%; P = .04) in FLT3/ITD-positive compared with FLT3/ITD-negative patients. In multivariate analyses, FLT3/ITD led to increased RI (hazard ratio [HR], 3.4; 95% CI, 1.46 to 7.94; P = .005), as did older age, female sex, shorter interval between CR and transplantation, and higher number of chemotherapy courses before achieving CR. FLT3/ITD positivity was associated with decreased LFS (HR, 0.37; 95% CI, 0.19 to 0.73; P = .002), along with older age and higher number of chemotherapy courses before achieving CR. CONCLUSION: FLT3/ITD adversely affected the outcome of HSCT in the same direction it does after chemotherapy; despite this, more than half of the patients harboring this mutation who received transplants were alive and leukemia free at 2 years. To further improve the results, use of FLT3 inhibitors before or after HSCT deserves investigation.

The immune reconstitution after an allogeneic stem cell transplant correlates with the risk of graft-versus-host disease and cytomegalovirus infection.

Aim of the study was to correlate the clinical outcome of eighteen patients who have undergone an allogeneic stem cell transplant (SCT) with the concentration in the peripheral blood (PB) of lymphocyte subpopulations evaluated at 1 year from transplant. The occurrence of acute GVHD and CMV infection correlated with the concentration of Tregs in the PB; CMV infection also correlated with the content of NK cells. The obtained results document that the concentration of Tregs in the PB after an allogeneic SCT may protect from GVHD and from CMV infection; the potential anti-viral role of NK cells is confirmed.

Identical outcome after autologous or allogeneic genoidentical hematopoietic stem-cell transplantation in first remission of acute myelocytic leukemia carrying inversion 16 or t(8;21): a retrospective study from the European Cooperative Group for Blood and Marrow Transplantation.

PURPOSE: Patients with acute myelocytic leukemia carrying inversion 16 (inv16) or t(8;21) have a better initial response to high-dose cytarabine than patients without these chromosomal abnormalities. They presently do not undergo transplantation in first remission (CR1), but there is concern about late relapses. PATIENTS AND METHODS: From 1990 to 2004, 325 adult patients received transplantations in CR1 (159 patients with inv16 and 166 patients with t(8;21), including 35 and 60 patients, respectively, with additional chromosomal abnormalities). Genoidentical allografts were performed in 64 patients with inv16 and 81 patients with t(8;21), and autografts were performed in 95 patients with inv16 and 85 patients with t(8;21). RESULTS: In patients with inv16, after allogeneic and autologous transplantation, the 5-year leukemia-free survival (LFS) rates were 59% and 66% (P = .5), the relapse incidence (RI) rates were 27% and 32% (P = .45), and the transplantation-related mortality (TRM) rates were 14% and 2% (P = .003), respectively. Female patients had a lower RI and a higher LFS. Additional chromosomal abnormalities, compared with no additional abnormalities, were associated with lower RI rate (12% v 34%, respectively; P = .01) and higher 5-year LFS rate (78% v 59%, respectively; P = .04). In patients with t(8;21), after allogeneic and autologous transplantation, the 5-year LFS rates were 60% and 66% (P = .69), the RI rates were 15% and 28% (P = .03), and the TRM rates were 24% and 6% (P = .003), respectively. Younger age and a lower WBC count at diagnosis were associated with a lower TRM and a better LFS. The TRM was lower and the RI was higher in patients with autologous transplantations versus allogeneic transplantations. CONCLUSION: Both autologous and allogeneic transplantation resulted in similar outcomes.

B-cell concentration in the apheretic product predicts acute graft-versus-host disease and treatment-related mortality of allogeneic peripheral blood stem cell transplantation.

BACKGROUND: The influence of the graft composition on the clinical outcome after allogeneic peripheral blood stem cell (PBSC) transplantation is not well established. METHODS: The cellular composition of the apheretic products obtained from 63 human leukocyte antigen-identical siblings was prospectively correlated with the outcome of patients with hematological malignancies undergoing an allogeneic PBSC transplant after myeloablative conditioning. The concentration of nuclear, mononuclear, CD34+, T-cell subsets, B cells, and natural killer cells in the graft has been analyzed. RESULTS: In univariate analysis, acute graft-versus-host disease (GVHD) correlated with the disease (P=0.002), with the phase of disease at transplant (P=0.01), and with the number of CD20+ cells infused (P=0.05). In multivariate analysis, a dose of CD20+ cells in the graft higher than the median dose remained the only factor negatively affecting the incidence of acute GVHD (P=0.01; 95% confidence interval [CI]: 0.12-0.78). In univariate analysis, treatment-related mortality (TRM) correlated with the disease (P=0.04) and was negatively affected by a dose of infused B cells greater than the median value (28% versus 50%; P=0.02). In multivariate analysis, TRM was close to statistical correlation with the dose of CD20+ cells (P=0.06; 95% CI: 0.02-1.05). No other clinical parameter was influenced by the composition of the graft. CONCLUSIONS: Our results suggest that the concentration of B cells in the apheretic product may predict the incidence of acute GVHD and TRM in patients undergoing an allogeneic PBSC transplantation and open the way to the new preventive and therapeutic strategies for the management of GVHD.