Histocompatibility assessment in hematopoietic stem cell transplantation: recommendations from the Italian Association of Immunogenetics and Biology of Transplantation (Associazione Italiana di Immunogenetica e Biologia dei Trapianti - AIBT).

The outcome of allogeneic hematopoietic stem cell transplantation (HSCT) is significantly influenced by the degree of HLA histocompatibility between donor and recipient. To provide shared indications for required histocompatibility testing and interpretation before HSCT, the Italian Society for Immunogenetics and Transplantation Biology (Associazione Italiana di Immunogenetica e Biologia dei Trapianti [AIBT]) gathered members and created a working group to discuss and develop recommendations for histocompatibility assessment in HSCT.After a review of the literature and multiple panel discussions, AIBT developed up-to-date recommendations for the resolution levels of HLA typing, histocompatibility definitions of patients and donors, importance of anti-HLA antibodies, and significance of NK alloreactivity, which are reported in this document. These recommendations have been shared with the Italian Group for Bone Marrow Transplantation (Gruppo Italiano per il Trapianto di Midollo Osseo, cellule staminali emopoietiche e terapia cellulare [GITMO]) and the Italian National Center for Transplantation (Centro Nazionale Trapianti [CNT]). Notably, the increased use of HLA-mismatched transplantation (i.e., mismatched unrelated, haploidentical) in recent years has made these indications even more relevant for the standardization and improvement of quality of care.This document represents a useful instrument for health care workers involved in the field of HSCT, enhancing synergy with transplant physicians and enabling greater optimization of the available resources.

SARS-COV-2 screening in allogeneic hematopoietic stem cell donors: Implications for the evaluation process and eligibility

Abstract Introduction Soon after the onset of the SARS-CoV-2 pandemic, viral screening by nasopharyngeal swab became mandatory for allogeneic hematopoietic stem cell (HSC) donor eligibility. Methods We described our monocenter experience with allogeneic HSC donors from February 1 to the October 31, 2020 to verify whether the introduction of SARS-CoV-2 screening altered the donor eligibility and/or entailed a prolongation of the evaluation process. Results A total of 21 allogeneic HSC donors were screened during the above-mentioned period upon request by the local transplant physicians or by the Italian Bone Marrow Donor Registry; among the HSC donors (n = 17) who completed the eligibility process and further received the nasopharyngeal swab, all but one were negative for the presence of SARS-CoV-2. The positive donor remained asymptomatic for the whole duration of the infection, which lasted six weeks. However, he was temporarily excluded from donation. The median duration of the evaluation process was not significantly different, compared to the same period of 2019 (p-value = 0.11). Conclusion The mandatory SARS-CoV-2 screening in allogeneic HSC donors allowed for the detection of 6% positivity in this monocenter series over a 9-month period. Despite the inconvenience of this unexpected non-eligibility, the exclusion of a SARS-CoV-2 positive donor represented an important safety measure for the donor, with respect to a new and still partially unknown virus. The screening did not alter the length of the donor evaluation and thus, did not cause a delay in the eligibility process.

SARS-COV-2 screening in allogeneic hematopoietic stem cell donors: Implications for the evaluation process and eligibility.

INTRODUCTION: Soon after the onset of the SARS-CoV-2 pandemic, viral screening by nasopharyngeal swab became mandatory for allogeneic hematopoietic stem cell (HSC) donor eligibility. METHODS: We described our monocenter experience with allogeneic HSC donors from February 1 to the October 31, 2020 to verify whether the introduction of SARS-CoV-2 screening altered the donor eligibility and/or entailed a prolongation of the evaluation process. RESULTS: A total of 21 allogeneic HSC donors were screened during the above-mentioned period upon request by the local transplant physicians or by the Italian Bone Marrow Donor Registry; among the HSC donors (n = 17) who completed the eligibility process and further received the nasopharyngeal swab, all but one were negative for the presence of SARS-CoV-2. The positive donor remained asymptomatic for the whole duration of the infection, which lasted six weeks. However, he was temporarily excluded from donation. The median duration of the evaluation process was not significantly different, compared to the same period of 2019 (p-value = 0.11). CONCLUSION: The mandatory SARS-CoV-2 screening in allogeneic HSC donors allowed for the detection of 6% positivity in this monocenter series over a 9-month period. Despite the inconvenience of this unexpected non-eligibility, the exclusion of a SARS-CoV-2 positive donor represented an important safety measure for the donor, with respect to a new and still partially unknown virus. The screening did not alter the length of the donor evaluation and thus, did not cause a delay in the eligibility process.

Allelic HLA Matching and Pair Origin Are Favorable Prognostic Factors for Unrelated Hematopoietic Stem Cell Transplantation in Neoplastic Hematologic Diseases: An Italian Analysis by the Gruppo Italiano Trapianto di Cellule Staminali e Terapie Cellulari, Italian Bone Marrow Donor Registry, and Associazione Italiana di Immunogenetica e Biologia dei Trapianti.

HLA molecules are important for immunoreactivity in allogeneic hematopoietic stem cell transplantation (HSCT). The Gruppo Italiano Trapianto di Cellule Staminali e Terapie Cellulari, Italian Bone Marrow Donor Registry, and Associazione Italiana di Immunogenetica e Biologia dei Trapianti promoted a retrospective observational study to evaluate HLA matching and the impact of allelic HLA mismatching and non-HLA factors on unrelated Italian HSCT outcomes. From 2012 to 2015, 1788 patients were enrolled in the study. The average donor age was 29 years and the average recipient age was 49 years. As a conditioning regimen, 71% of the patients received myeloablative conditioning. For GVHD prophylaxis, 76% received either antithymocyte or anti-T lymphocyte globulin, cyclosporine A, and methotrexate. Peripheral blood was the stem cell source in 80%. The median duration of follow-up was 53 months. Regarding HLA matching, 50% of donor-recipient pairs were 10/10 matched, 38% had 1 mismatch, and 12% had 2 or more mismatches. A total of 302 pairs shared Italian origin. Four-year overall survival (OS), progression-free survival, GVHD-free relapse-free survival, and relapse rates were 49%, 40%, 22%, and 34%, respectively. The 4-year NRM was 27%, and the 100-day cumulative incidence of grade ≥II acute GVHD (aGVHD) was 26%. In multivariate analysis, 9/10 and ≤8/10 HLA allele-matched pairs were associated with worse OS (P = .04 and .007, respectively), NRM (P = .007 and P < .0001, respectively), and grade III-IV aGVHD (P = .0001 and .01, respectively). Moreover, the incidences of grade II-IV aGVHD (P = .001) and chronic GVHD (P = .002) were significantly lower in Italian pairs. In conclusion, 10/10 HLA matching is a favorable prognostic factor for unrelated HSCT outcome in the Italian population. Moreover, the presence of 2 HLA-mismatched loci was associated with a higher NRM (P < .0001) and grade II-IV aGVHD (P = .006) and a poorer OS (P = .001) compared with 1 HLA-mismatched locus in early or intermediate disease phases. Finally, we found that Italian donor and recipient origin is a favorable prognostic factor for GVHD occurrence.

The Rome Transplant Network model compared to the Italian Bone Marrow Donor Registry activity for unrelated donor search process and transplant efficiency for hematologic malignancy.

BACKGROUND: From 2011 to 2014, a total of 71% of the 3834 patients with hematologic malignancies successfully identified a matched unrelated donor (MUD) through the Italian Bone Marrow Donor Registry (IBMDR), corresponding to a transplant efficiency of 62%. STUDY DESIGN AND METHODS: From 2006, the Rome Transplant Network (RTN) followed a hierarchical selection strategy for the alternative donor search: first MUD, second cord blood, and third haploidentical donor. Using a low-resolution HLA, a preliminary query (PQ) was performed in all cases with assignment of good or poor score if more or less than 10 MUDs were identified in Bone Marrow Donors Worldwide. Herein we assessed the utility of PQ and of high-resolution (HR) HLA from the start of the search. Moreover, we compared the donor identification and the transplant efficiency between IBMDR and RTN. RESULTS: At RTN 79% of 417 patients met a good PQ with a 50% MUD identification versus 12.5% with poor PQ. Our policy led to 78 and 74% of alternative donor identification and transplant efficiency, respectively, higher than IBMDR data equal to 71% (p = 0.007) and 62% (p < 0.0001). The timing for donor identification was significantly reduced using HR HLA at the start of the search from 88 to 66 days at IBMDR (p < 0.001) and from 61 to 41 days at RTN (p < 0.001). CONCLUSIONS: Both PQ and HR HLA at the start of the process represents a useful tool to address the search towards the best and timely donor choice. Moreover, establishing a specific donor policy significantly improves the transplant efficiency.

Quality of harvest and role of cell dose in unrelated bone marrow transplantation: an Italian Bone Marrow Donor Registry-Gruppo Italiano Trapianto di Midollo Osseo Study.

In this study, we investigated the factors affecting cell dose harvest and the role of cell dose on outcome. We analysed data from a cohort of 703 patients who underwent unrelated bone marrow transplantation facilitated by IBMDR in GITMO centers between 2002 and 2008. The median-infused cell doses is 3.7 × 10(8)/kg, the correlation between the nucleated cells requested from transplant centers and those harvested by collection centers was adequate. A harvested/requested cells ratio lower than 0.5 was observed only in 3% of harvests. A volume of harvested marrow higher than the median value of 1270 ml was related to a significant lower infused cell dose (χ(2): 44.4; P < 0.001). No patient- or donor-related variables significantly influenced the cell dose except for the recipient younger age (χ(2): 95.7; P < 0.001) and non-malignant diseases (χ(2): 33.8; P < 0.001). The cell dose resulted an independent predictor factor for a better outcome in patients affected by non-malignant disease (P = 0.05) while early disease malignant patients receiving a lower cell dose showed a higher risk of relapse (P = 0.05).

Outcome of patients activating an unrelated donor search for severe acquired aplastic anemia.

Patients with severe aplastic anemia (SAA) without a sibling donor receive immunosuppressive treatment (IST) with anti-thymocyte globulin (ATG). In the case of no response to IST, a voluntary unrelated donor (VUD) search is usually started. This study analyzes the outcome of ATG-refractory SAA patients activating a VUD search. Of 179 patients, 68 had at least one HLA-A, -B, and -DR matched donor identified and underwent HSCT while 50 also with a donor were not transplanted because of early death (8), late response to IST (34), transplant refusal (1), or other (7). Conversely, 61 had no matched donor, 13 of those ultimately received a mismatched HSCT. All but one received marrow stem cells. Among patients aged <17 years, those with at least one matched donor had a significant higher 4-year survival as compared to others (79% ± 6% versus 53% ± 10%, P = 0.01). There was also a survival advantage independent of recipient age when the donor search was initiated in the recent 2000-2005 study-period (74% ± 6% versus 47% ± 10%, P < 0.05). In multivariate analysis, the identification of a matched VUD tended to impact favourably on survival in patients with a recent donor search (P = 0.07). This study provides evidence for the use of unrelated donor HSCT in children and adults with IST-refractory SAA.

Allogeneic hematopoietic cell transplantation from unrelated donors in multiple myeloma: study from the Italian Bone Marrow Donor Registry.

To evaluate trends in allografting from unrelated donors, we conducted a study on 196 consecutive myeloma patients transplanted between 2000 and 2009 in Italy. Twenty-eight percent, 37%, and 35%, respectively, received myeloablative, reduced-intensity, and nonmyeloablative conditioning. In these 3 cohorts, 1-year and 5-year transplantation-related mortalities were 28.8% and 37.0%, 20.3% and 31.3%, and 25.0% and 30.3%, respectively (P = .745). Median overall survival (OS) and event-free survival from transplantation for the 3 cohorts were 29 and 10 months, 11 and 6 months, and 32 and 13 months, respectively (P = .039 and P = .049). Overall cumulative incidences of acute and chronic graft-versus-host-disease (GVHD) were 46.1% and 51.1%. By Cox multivariate analyses, chronic GVHD was significantly associated with longer OS (hazard ratio [HR], .51; P = .009), whereas the use of peripheral blood stem cells was borderline significant (HR, .55; P = .051). Better response posttransplantation was associated with longer event-free survival (HR, 2.13 to 4.25; P < .001). Acute GVHD was associated with poorer OS (HR, 2.53; P = .001). This analysis showed a strong association of acute and chronic GVHD and depth of response posttransplantation with clinical outcomes. Long-term disease control remains challenging regardless of the conditioning. In the light of these results, prospective trials may be designed to better define the role of allografting from unrelated donors in myeloma.

Estimation of human leukocyte antigen class I and class II high-resolution allele and haplotype frequencies in the Italian population and comparison with other European populations.

The high-resolution (HR) allele and haplotype frequencies of class I and II human leukocyte antigen (HLA) system were determined in the Italian population from a sample of donors recruited in the Italian Bone Marrow Donor Registry (IBMDR). This study analyzed the HLA-A, -B, -C, -DRB1, and -DQB1 loci. Two different samples were used: donors HR typed at least for one allele, usually when selected for donor-recipient matching (respectively: 3596, 7591, 4715, 57345, and 8196), to make a list of the observed alleles and determine the relative frequencies of the alleles in each class of the corresponding antigen; donors HR randomly typed for both the alleles (respectively: 975, 1643, 1569, 22114, and 2087) to estimate the allele and haplotype frequencies, and two loci linkage disequilibrium. The number of alleles showing a frequency >1% on the total number of observed alleles are 18/75 HLA-A, 28/142 -B, 17/57 -C, 23/154 -DRB1, and 13/31 -DQB1. In each locus they account for more than 88% of the total cumulative frequencies. The most frequent alleles are A*02: 01, B*35: 01, C*04:01, DRB1*07:01, DQB1*03:01. The most frequent five-locus haplotype in the 338 donors randomly typed is A*01: 01-C*07:01-B*08: 01-DRB1*03:01-DQB1*02:01. The genetic comparison of the Italian population with 16 European populations shows a south-north gradient.

Nonpermissive HLA-DPB1 disparity is a significant independent risk factor for mortality after unrelated hematopoietic stem cell transplantation.

The importance of donor-recipient human leukocyte antigen (HLA)-DPB1 matching for the clinical outcome of unrelated hematopoietic stem cell transplantation (HSCT) is controversial. We have previously described an algorithm for nonpermissive HLA-DPB1 disparities involving HLA-DPB1*0901,*1001,*1701,*0301,*1401,*4501, based on T-cell alloreactivity patterns. By revisiting the immunogenicity of HLA-DPB1*02, a modified algorithm was developed and retrospectively tested in 621 unrelated HSCTs facilitated through the Italian Registry for oncohematologic adult patients. The modified algorithm proved to be markedly more predictive of outcome than the original one, with significantly higher Kaplan-Meier probabilities of 2-year survival in permissive compared with nonpermissive transplantations (55% vs 39%, P = .005). This was the result of increased adjusted hazards of nonrelapse mortality (hazard ratio [HR] = 1.74; confidence interval [CI], 1.19-2.53; P = .004) but not of relapse (HR = 1.02; CI, 0.73-1.42; P = .92). The increase in the hazards of overall mortality by nonpermissive HLA-DPB1 disparity was similar in 10 of 10 (HR = 2.12; CI, 1.23-3.64; P = .006) and 9 of 10 allele-matched transplantations (HR = 2.21; CI, 1.28-3.80; P = .004), both in early-stage and in advanced-stage disease. These data call for revisiting current HLA matching strategies for unrelated HSCT, suggesting that searches should be directed up-front toward identification of HLA-DPB1 permissive, 10 of 10 or 9 of 10 matched donors.

Early (day -7) versus conventional (day -1) inception of cyclosporine-A for graft-versus-host disease prophylaxis after unrelated donor hematopoietic stem cell transplantation in children. Long-term results of an AIEOP prospective, randomized study.

We carried out a randomized, multicenter study comparing the inception of cyclosporine- A (CsA) on day -7 to conventional CsA (on day -1) to evaluate the influence of this modification on graft-versus-host disease (GVHD), treatment-related mortality (TRM), relapse rate (RR), and event-free survival (EFS) in children with hematologic malignancies given unrelated donor (UD) hematopoietic stem cell transplantation (HSCT). Between 1997 and 2002, 152 children transplanted for acute leukemia (102), myelodysplastic syndromes (23), chronic myelogenous leukemia (20), and non-Hodgkin lymphoma (7) were enrolled in the study and randomized to receive either early CsA (group 1, N = 72) or conventional CsA (group 2, N = 80), after stratification according to HLA compatibility and disease phase. The cumulative incidence of both grade II-IV and grade II-IV acute GVHD (aGVHD), as well as of chronic GVHD (cGVHD), did not differ between the 2 groups. No significant differences were observed also with regard to TRM and RR. The 8-year Kaplan-Meier estimates of EFS were 56% in group 1, and 46% in group 2 (P = NS). In the Cox model, advanced disease phase, male recipient, older donor, and occurrence of grade III-IV aGVHD predicted inferior overall EFS. These data indicate that early inception of CsA does not improve posttransplantation outcome of children with hematologic malignancies given UD-HSCT.

Unrelated donor haematopoietic cell transplantation after non-myeloablative conditioning for patients with high-risk multiple myeloma.

BACKGROUND: Allografting induces long-term molecular remissions and possibly cure in myeloma patients. The development of non-myeloablative conditionings has reduced the transplant-related mortality (TRM) associated with myeloablation and extended the eligible age for transplantation. Moreover, high response rates are reported especially when allografting is preceded by cytoreductive high-dose chemotherapy. We investigated the feasibility of unrelated donor non-myeloablative transplantation as either part of the initial treatment plan or as salvage treatment in heavily pretreated patients. METHODS: Twenty-two patients underwent non-myeloablative allografting, 10 as part of their initial treatment and 12 at relapse. Donors were matched for HLA-A, B, C, DRB1 and DQB1 by high-resolution typing. Only one single class I allele disparity was allowed. Conditioning consisted of fludarabine 90 mg/m(2) and 2 Gy total body irradiation. Graft-vs.-host disease (GVHD) prophylaxis included cyclosporin and mycophenolate mofetil. RESULTS: All patients except two (91%) readily engrafted. After a median follow-up of 20 (10-30) months, incidences of grade II-IV acute and extensive chronic GVHD were 50% and 61%. Overall response (OR) was 55%, with four (20%) complete and seven (35%) partial remissions. However, in patients allografted up-front OR was 89% whereas in the heavily pretreated group OR was 27% (P = 0.01). Two-year overall and event-free survivals were both 79% in the group transplanted up-front and 27% and 25% among relapsed patients (P = 0.025 and P = 0.006, respectively). Overall, six patients died of TRM and three of disease progression. CONCLUSIONS: Unrelated donor non-myeloablative allografting is feasible in myeloma. Disease control appears more pronounced when patients are treated soon after diagnosis.

Unrelated donor marrow transplantation in childhood: a report from the Associazione Italiana Ematologia e Oncologia Pediatrica (AIEOP) and the Gruppo Italiano per il Trapianto Midollo Osseo (GITMO).

BACKGROUND AND OBJECTIVES: Unrelated donor bone marrow transplant (UD-BMT) has become an attractive, alternative source of hematopoietic cells for patients lacking a matched sibling. The aim of this paper is to report on 520 patients below 19 years of age undergoing UD BMT in 31 Italian centers between September 1989 and December 2001, and to focus on the results achieved in the 423 patients grafted before December 2000. DESIGNS AND METHODS: In 1989 the Italian Bone Marrow Transplant Group (GITMO) and the Italian Association for Pediatric Hematology and Oncology (AIEOP) established the Italian Bone Marrow Donor Registry (IBMDR) to facilitate donor search and marrow procurement for patients lacking an HLA identical sibling. By the end of December 2001, 296,720 HLA-A, B typed volunteer donors had been cumulatively registered and 3,411 searches had been activated for Italian patients. At least one HLA-A, B, DRB1 matched donor was found for 54% of the patients and 520 UD BMTs were performed in patients below 19 years of age before December 2001. Since 1999 more than 90% of the patients < or = 14 years old, and more than 50% of the patients 15-18 years old undergoing UD BMT have been treated in AIEOP institutions. In 50% of the cases donors were found in the IBMDR, and in 50% they were found in 14 other Registries. The average time from search activation to transplant was 6 months for diseases other than chronic myeloid leukemia (CML), while for CML it was 8.7 months. RESULTS: Actuarial 100-day transplant-related mortality (TRM) was 32% in patients grafted between 1989 and 1997, and 21% for patients grafted after 1998 (p = 0.003). Twenty-eight per cent of the patients developed grade III or IV acute graft-versus-host disease (GvHD), and 20% developed extensive chronic GvHD. The rate of disease-free survival at three years was 37% for patients with acute lymphoblastic leukemia, 38% for acute myeloid leukemia or myelodysplastic syndrome patients, 59% for patients with inborn errors, and 51% for patients with CML. INTERPRETATION AND CONCLUSIONS: We conclude that the IBMDR has benefited a substantial number of patients lacking a matched sibling and has facilitated the recruitment of UDs into the international donor pool. Results show a positive trend after 1998, mainly due to a decrease in transplant-related-mortality.