Impact of donor NKG2D and MICA gene polymorphism on clinical outcomes of adult and paediatric allogeneic cord blood transplantation for malignant diseases.

OBJECTIVES: NKG2D is an activating receptor expressed by natural killer (NK) and CD8+ T cells and activation intensity varies by NKG2D expression level or nature of its ligand. An NKG2D gene polymorphism determines high (HNK1) or low (LNK1) expression. MICA is the most polymorphic NKG2D ligand and stronger effector cell activation associates with methionine rather than valine at residue 129. We investigated correlation between cord blood (CB) NKG2D and MICA genotypes and haematopoietic stem cell (HSC) transplant outcome. METHODS: We retrospectively studied 267 CB HSC recipients (178 adult and 87 paediatric) who underwent transplant for malignant disease between 2007 and 2018, analysing CB graft DNA for NKG2D and MICA polymorphisms using Sanger sequencing. Multivariate analysis was used to correlate these results with transplant outcomes. RESULTS: In adult patients, LNK1 homozygous CB significantly improved 60-day neutrophil engraftment (hazard ratio (HR) 0.6; 95% confidence interval (CI) 0.4-0.9; p = .003). In paediatrics, HNK1 homozygous CB improved 60-day engraftment (HR 0.4; 95% CI 0.2-0.7; p = .003), as did MICA-129 methionine+ CB grafts (HR 1.7 95% CI 1.1-2.6; p = .02). CONCLUSION: CB NKG2D and MICA genotypes potentially improve CB HSC engraftment. However, results contrast between adult and paediatric recipients and may reflect transplant procedure disparities between cohorts.

HLA-B leader and survivorship after HLA-mismatched unrelated donor transplantation.

Hematopoietic cell transplantation (HCT) from HLA-mismatched unrelated donors can cure life-threatening blood disorders, but its success is limited by graft-versus-host disease (GVHD). HLA-B leaders encode methionine (M) or threonine (T) at position 2 and give rise to TT, MT, or MM genotypes. The dimorphic HLA-B leader informs GVHD risk in HLA-B-mismatched HCT. If the leader influences outcome in other HLA-mismatched transplant settings, the success of HCT could be improved for future patients. We determined leader genotypes for 10 415 patients receiving a transplant between 1988 and 2016 from unrelated donors with one HLA-A, HLA-B, HLA-C, HLA-DRB1, or HLA-DQB1 mismatch. Multivariate regression methods were used to evaluate risks associated with patient leader genotype according to the mismatched HLA locus and with HLA-A, HLA-B, HLA-C, HLA-DRB1, or HLA-DQB1 mismatching according to patient leader genotype. The impact of the patient leader genotype on acute GVHD and mortality varied across different mismatched HLA loci. Nonrelapse mortality was higher among HLA-DQB1-mismatched MM patients compared with HLA-DQB1-mismatched TT patients (hazard ratio, 1.35; P = .01). Grades III to IV GVHD risk was higher among HLA-DRB1-mismatched MM or MT patients compared with HLA-DRB1-mismatched TT patients (odds ratio, 2.52 and 1.51, respectively). Patients tolerated a single HLA-DQB1 mismatch better than mismatches at other loci. Outcome after HLA-mismatched transplantation depends on the HLA-B leader dimorphism and the mismatched HLA locus. The patient's leader variant provides new information on the limits of HLA mismatching. The success of HLA-mismatched unrelated transplantation might be enhanced through the judicious selection of mismatched donors for a patient's leader genotype.

Recipients Receiving Better HLA-Matched Hematopoietic Cell Transplantation Grafts, Uncovered by a Novel HLA Typing Method, Have Superior Survival: A Retrospective Study.

HLA matching at an allelic-level resolution for volunteer unrelated donor (VUD) hematopoietic cell transplantation (HCT) results in improved survival and fewer post-transplant complications. Limitations in typing technologies used for the hyperpolymorphic HLA genes have meant that variations outside of the antigen recognition domain (ARD) have not been previously characterized in HCT. Our aim was to explore the extent of diversity outside of the ARD and determine the impact of this diversity on transplant outcome. Eight hundred ninety-one VUD-HCT donors and their recipients transplanted for a hematologic malignancy in the United Kingdom were retrospectively HLA typed at an ultra-high resolution (UHR) for HLA-A, -B, -C, -DRB1, -DQB1, and -DPB1 using next-generation sequencing technology. Matching was determined at full gene level for HLA class I and at a coding DNA sequence level for HLA class II genes. The HLA matching status changed in 29.1% of pairs after UHR HLA typing. The 12/12 UHR HLA matched patients had significantly improved 5-year overall survival when compared with those believed to be 12/12 HLA matches based on their original HLA typing but were found to be mismatched after UHR HLA typing (54.8% versus 30.1%, P = .022). Survival was also significantly better in 12/12 UHR HLA-matched patients when compared with those with any degree of mismatch at this level of resolution (55.1% versus 40.1%, P = .005). This study shows that better HLA matching, found when typing is done at UHR that includes exons outside of the ARD, introns, and untranslated regions, can significantly improve outcomes for recipients of a VUD-HCT for a hematologic malignancy and should be prospectively performed at donor selection.

Immunotherapy after hematopoietic stem cell transplantation using umbilical cord blood-derived products.

Umbilical cord blood (UCB) is being increasingly used as a source of hematopoietic stem cells (HSC) for transplantation. UCB transplantation (UCBT) has some advantages such as less stringent HLA-matching requirements, fast availability of the graft and reduced incidence and severity of graft-versus-host disease. However, UCBT is also associated with a higher incidence of infection, graft failure, slow engraftment and slow immune reconstitution. UCB is mainly used as a source of HSC; however, it is also rich in immune cells that could be used to treat some of the main complications post-UCBT as well as other diseases, thus implicating the use of UCB for immunotherapy. Here, we aim to describe some of the therapies currently developed that use UCB as a cell source, focusing in particular on regulatory T cells and natural killer cells.

Natural killer cells differentiated in vitro from cord blood CD34+ cells are more advantageous for use as an immunotherapy than peripheral blood and cord blood natural killer cells.

BACKGROUND AIMS: Natural killer (NK) cells have the potential to become a successful immunotherapy as they can target malignant cells without being direct effectors of graft-versus-host disease. Our group has previously shown that large numbers of functional NK cells can be differentiated in vitro from umbilical cord blood (CB) CD34+ cells. To produce a clinically relevant and effective immunotherapy, we hypothesized that it is essential that the NK cells are able to proliferate and persist in vivo while maintaining an optimal activation status and killing capacity. METHODS: We evaluated the proliferation capacity, telomere length and terminal differentiation markers expressed by NK cells differentiated in vitro. We also determined how their cytotoxicity compared with peripheral blood (PB) NK cells and CBNK cells when targeting patient acute myeloid leukemia (AML) blasts and solid tumor cell lines. RESULTS: We found that the differentiated NK cells could respond to interleukin-2 and proliferate in vitro. Telomere length was significantly increased, whereas CD57 expression was significantly reduced compared with PBNK cells. The cytotoxicity of the differentiated NK cells was equivalent to that of the PBNK and CBNK cell controls, and priming consistently led to higher levels of killing of patient leukemic blasts and solid tumor cell lines in vitro. Interestingly, this activation step was not required to observe killing of patient AML blasts in vivo. CONCLUSION: We are able to generate NK cells from CBCD34+ cells in high numbers, allowing for multiple infusions of highly cytotoxic NK cells that have potential to further proliferate in vivo, making them a desirable product for application as an immunotherapy in the clinic.

Umbilical cord blood plasma contains soluble NKG2D ligands that mediate loss of natural killer cell function and cytotoxicity.

NK cells play a key role in innate elimination of virally infected or neoplastic cells but they can be circumvented by immunoevasive mechanisms enabling viral spread or tumor progression. Engagement of the NKG2D activating receptor with soluble forms of its ligand is one such mechanism of inducing NK cell hyporesponsiveness. Interestingly, this immunoevasive strategy among others is described at the maternal-fetal interface where tolerance of the semi-allogeneic fetus is required to allow successful human pregnancy. Understanding of maternal-fetal tolerance is increasing but mechanisms preventing alloreactivity of fetal immune cells against the maternal host are less well understood. The study of umbilical cord blood has enabled insight of the fetal immune system, which appears immature and inert. We have found that soluble NKG2D ligands (sNKG2DLs) are present in cord blood plasma (CBP) and associate with adult NK cell hyporesponsiveness demonstrated by reduced CD107a expression and secretion of IFN-γ upon stimulation. The capacity of NK cells to kill K562 cells or proliferate was also reduced by incubation with CBP; however, physical removal of sNKG2DL from CBP restored K562 lytic function and NKG2D expression. Therefore, our results strongly suggest sNKG2DLs are expressed in CBP as a mechanism of fetal-maternal tolerance in human pregnancy.

Polymorphism in TGFB1 is associated with worse non-relapse mortality and overall survival after stem cell transplantation with unrelated donors.

Transforming growth factor ß-1, encoded by the TGFB1 gene, is a cytokine that plays a central role in many physiological and pathogenic processes. We have sequenced TGFB1 regulatory region and assigned allelic genotypes in a large cohort of hematopoietic stem cell transplantation patients and donors. In this study, we analyzed 522 unrelated donor-patient pairs and examined the combined effect of all the common polymorphisms in this genomic region. In univariate analysis, we found that patients carrying a specific allele, 'p001', showed significantly reduced overall survival (5-year overall survival 30.7% for p001/p001 patients vs. 41.6% others; P=0.032) and increased non-relapse mortality (1-year non-relapse mortality: 39.0% vs. 25.4%; P=0.039) after transplantation. In multivariate analysis, the presence of a p001/p001 genotype in patients was confirmed as an independent factor for reduced overall survival [hazard ratio=1.53 (1.04-2.24); P=0.031], and increased non-relapse mortality [hazard ratio=1.73 (1.06-2.83); P=0.030]. In functional experiments we found a trend towards a higher percentage of surface transforming growth factor ß-1-positive regulatory T cells after activation when the cells had a p001 allele (P=0.07). Higher or lower production of transforming growth factor ß-1 in the inflammatory context of hematopoietic stem cell transplantation may influence the development of complications in these patients. Findings indicate that TGFB1 genotype could potentially be of use as a prognostic factor in hematopoietic stem cell transplantation risk assessment algorithms.

Cryopreservation has no effect on function of natural killer cells differentiated in vitro from umbilical cord blood CD34(+) cells.

BACKGROUND AIMS: Natural killer (NK) cells offer the potential for a powerful cellular immunotherapy because they can target malignant cells without being direct effectors of graft-versus-host disease. We have previously shown that high numbers of functional NK cells can be differentiated in vitro from umbilical cord blood (CB) CD34(+) cells. To develop a readily available, off-the-shelf cellular product, it is essential that NK cells differentiated in vitro can be frozen and thawed while maintaining the same phenotype and functions. METHODS: We evaluated the phenotype and function of fresh and frozen NK cells differentiated in vitro. We also assessed whether the concentration of NK cells at the time of freezing had an impact on cell viability. RESULTS: We found that cell concentration of NK cells at the time of freezing did not have an impact on their viability and on cell recovery post-thaw. Moreover, freezing of differentiated NK cells in vitro did not affect their phenotype, cytotoxicity and degranulation capacity toward K562 cells, cytokine production and proliferation. CONCLUSIONS: We are therefore able to generate large numbers of functional NK cells from CB CD34(+) cells that maintain the same phenotype and function post-cryopreservation, which will allow for multiple infusions of a highly cytotoxic NK cell product.

Harvests from bone marrow donors who weigh less than their recipients are associated with a significantly increased probability of a suboptimal harvest yield.

BACKGROUND: Previous studies have demonstrated the importance of bone marrow (BM) harvest yield in determining transplant outcomes, but little is known regarding donor and procedure variables associated with achievement of an optimal yield. We hypothesized that donor demographics and variables relating to the procedure were likely to impact the yield (total nucleated cells [TNCs]/kg recipient weight) and quality (TNCs/mL) of the harvest. STUDY DESIGN AND METHODS: To test our hypothesis, BM harvests of 110 consecutive unrelated donors were evaluated. The relationship between donor or procedure characteristics and the BM harvest yield was examined. RESULTS: The relationship between donor and recipient weight significantly influenced the harvest yield; only 14% of BM harvests from donors who weighed less than their recipient achieved a TNC count of more than 4 × 10(8) /kg compared to 56% of harvests from donors heavier than their recipient (p = 0.001). Higher-volume harvests were significantly less likely to achieve an optimal yield than lower-volume harvests (32% vs. 78%; p = 0.007), and higher-volume harvests contained significantly fewer TNCs/mL, indicating peripheral blood contamination. BM harvest quality also varied significantly between collection centers adding to recent concerns regarding maintenance of BM harvest expertise within the transplant community. CONCLUSION: Since the relationship between donor and recipient weight has a critical influence yield, we recommend prioritizing this secondary donor characteristic when selecting from multiple well-matched donors. Given the declining number of requests for BM harvests, it is crucial that systems are developed to train operators and ensure expertise in this procedure is retained.

Predonation health-related quality of life scores predict time to recovery in hematopoietic stem cell donors.

The physical reactions to hematopoietic stem cell donation have been extensively studied, but less is known about factors that predict poorer donation experiences. The aim of this prospective study was to examine demographic and health-related quality of life (HRQOL) factors that might be associated with recovery and side effects. We also described the changes in HRQOL during the donation process. In total, 275 peripheral blood stem cell (PBSC) and 37 bone marrow (BM) consecutive donors completed the SF-36 questionnaire predonation and 4 weeks, and 3 months postdonation. Predonation HRQOL markers were the strongest predictors of time to recovery. Poorer predonation physical health was associated with longer recovery (P = .017) and certain side effects in PBSC donors. Poorer predonation mental health was associated with longer recovery in BM donors (P = .03) and pain after PBSC donation (P = .003). Physical HRQOL scores declined significantly from predonation to 4 weeks postdonation. This was shown both for PBSC and BM donors (P < .001 and P = .009, respectively), but the decline was much greater for BM donors. There was a return to predonation HRQOL values 3 months after donation in both groups with values well above the mean of the general population (P < .001).

Female donors and donors who are lighter than their recipient are less likely to meet the CD34+ cell dose requested for peripheral blood stem cell transplantation.

BACKGROUND: It is of clinical relevance to recognize donors who are unlikely to meet the requested stem cell dose for transplantation, as this group may benefit from an alternative mobilization regimen. This study was performed to evaluate the frequency of unrelated donor peripheral blood stem cell (PBSC) collections that meet the target yield and the impact of donor factors on this. STUDY DESIGN AND METHODS: All sequential PBSC collections facilitated by the national registry (n = 323) from January through December 2011 were analyzed. Donor factors analyzed included age, sex, weight, and presence of a central line. RESULTS: In univariate analyses, we found that reaching the target yield was significantly associated with a higher donor weight (85.6 kg vs. 75.3 kg, p < 0.001), male donor sex (55% vs. 19%, p < 0.001), a positive difference in weight between donor and recipient (4.3 kg vs. -8 kg, p < 0.001), and a higher volume of blood processed (13.8 L vs. 11.9 L, p < 0.001). After stepwise binary logistic regression, sex (p < 0.001) and difference between donor and recipient weight (p < 0.005) remained significantly associated with target yield being met after 1 day of collection. CONCLUSIONS: This study shows than women and donors who are lighter than their recipient have a decreased likelihood of meeting the transplant physician's requested dose. New strategies to improve mobilization in such donors are needed. These findings may also impact future donor recruitment strategies.

Subsequent donation requests among 2472 unrelated hematopoietic progenitor cell donors are associated with bone marrow harvest.

Approximately 1 in 20 unrelated donors are asked to make a second donation of hematopoietic progenitor cells, the majority for the same patient. Anthony Nolan undertook a study of subsequent hematopoietic progenitor cell donations made by its donors from 2005 to 2011, with the aims of predicting those donors more likely to be called for a second donation, assessing rates of serious adverse reactions and examining harvest yields. This was not a study of factors predictive of second allografts. During the study period 2591 donations were made, of which 120 (4.6%) were subsequent donations. The median time between donations was 179 days (range, 21-4016). Indications for a second allogeneic transplant included primary graft failure (11.7%), secondary graft failure (53.2%), relapse (30.6%) and others (1.8%). On multivariate analysis, bone marrow harvest at first donation was associated with subsequent donation requests (odds ratio 2.00, P=0.001). The rate of serious adverse reactions in donors making a subsequent donation appeared greater than the rate in those making a first donation (relative risk=3.29, P=0.005). Harvest yields per kilogram recipient body weight were equivalent between donations, although females appeared to have a lower yield at the subsequent donation. Knowledge of these factors will help unrelated donor registries to counsel their donors.

Effect of T-cell-epitope matching at HLA-DPB1 in recipients of unrelated-donor haemopoietic-cell transplantation: a retrospective study.

BACKGROUND: The risks after unrelated-donor haemopoietic-cell transplantation with matched HLA-A, HLA-B, HLA-C, HLA-DRB1, HLA-DQB1 alleles between donor and recipient (10/10 matched) can be decreased by selection of unrelated donors who also match for HLA-DPB1; however, such donors are difficult to find. Classification of HLA-DPB1 mismatches based on T-cell-epitope groups could identify mismatches that might be tolerated (permissive) and those that would increase risks (non-permissive) after transplantation. We did a retrospective study to compare outcomes between permissive and non-permissive HLA-DPB1 mismatches in unrelated-donor haemopoietic-cell transplantation. METHODS: HLA and clinical data for unrelated-donor [corrected] transplantations submitted to the International Histocompatibility Working Group in haemopoietic-cell transplantation were analysed retrospectively. HLA-DPB1 T-cell-epitope groups were assigned according to a functional algorithm based on alloreactive T-cell crossreactivity patterns. Recipients and unrelated donors matching status were classified as HLA-DPB1 match, non-permissive HLA-DPB1 mismatch (those with mismatched T-cell-epitope groups), or permissive HLA-DPB1 mismatch (those with matched T-cell-epitope groups). The clinical outcomes assessed were overall mortality, non-relapse mortality, relapse, and severe (grade 3-4) acute graft-versus-host disease (aGvHD). FINDINGS: Of 8539 transplantations, 5428 (64%) were matched for ten of ten HLA alleles (HLA 10/10 matched) and 3111 (36%) for nine of ten alleles (HLA 9/10 matched). Of the group overall, 1719 (20%) were HLA-DPB1 matches, 2670 (31%) non-permissive HLA-DPB1 mismatches, and 4150 (49%) permissive HLA-DPB1 mismatches. In HLA 10/10-matched transplantations, non-permissive mismatches were associated with a significantly increased risk of overall mortality (hazard ratio [HR] 1·15, 95% CI 1·05-1·25; p=0·002), non-relapse mortality (1·28, 1·14-1·42; p<0·0001), and severe aGvHD (odds ratio [OR] 1·31, 95% CI 1·11-1·54; p=0·001), but not relapse (HR 0·89, 95% CI 0·77-1·02; p=0·10), compared with permissive mismatches. There were significant differences between permissive HLA-DPB1 mismatches and HLA-DPB1 matches in terms of non-relapse mortality (0·86, 0·75-0·98; p=0·03) and relapse (1·34, 1·17-1·54; p<0·0001), but not for overall mortality (0·96, 0·87-1·06; p=0·40) or aGvHD (OR 0·84, 95% CI 0·69-1·03; p=0·09). In the HLA 9/10 matched population, non-permissive HLA-DPB1 mismatches also increased the risk of overall mortality (HR 1·10, 95% CI 1·00-1·22; p=0·06), non-relapse mortality (1·19, 1·05-1·36; p=0·007), and severe aGvHD (OR 1·37, 95% CI 1·13-1·66; p=0·002) compared with permissive mismatches, but the risk of relapse was the same in both groups (HR 0·93, 95% CI 0·78-1·11; p=0·44). Outcomes for HLA 10/10-matched transplantations with non-permissive HLA-DPB1 mismatches did not differ substantially from those for HLA 9/10-matched transplantations with permissive HLA-DPB1 mismatches or HLA-DPB1 matches. INTERPRETATION: T-cell-epitope matching defines permissive and non-permissive HLA-DPB1 mismatches. Avoidance of an unrelated donor with a non-permissive T-cell-epitope mismatch at HLA-DPB1 might provide a practical clinical strategy for lowering the risks of mortality after unrelated-donor haemopoietic-cell transplantation. FUNDING: National Institutes of Health; Associazione Italiana per la Ricerca sul Cancro; Telethon Foundation; Italian Ministry of Health; Cariplo Foundation; National Cancer Institute; National Heart, Lung and Blood Institute; National Institute of Allergy and Infectious Diseases; Office of Naval Research; IRGHET Paris; Swedish Cancer Society; Children's Cancer Foundation; Swedish Research Council; Cancer Society in Stockholm; Karolinska Institutet; and Leukemia and Lymphoma Society.

Cytomegalovirus-specific CD8+ T cells targeting different peptide/HLA combinations demonstrate varying T-cell receptor diversity.

Cytomegalovirus (CMV) infection and reactivation pose a serious threat for patients after haematopoietic stem cell transplantation. We have previously shown that CD8(+) T cells targeting different CMV epitopes correlate with protection at different threshold frequencies in those patients. To investigate if this may relate to a different quality of these cells here we analyse the T-cell receptor diversity of pp50 (245-253)/HLA-A*0101 specific CD8(+) T cells with that of CD8(+) T cells targeting various pp65 peptides. The results from this pilot study show differences in the breadth of the T-cell receptor usage of the different cell populations. We observe for the first time that the T-cell receptor Vß CDR3 spectratypes used by CMV pp50 (245-253)/HLA-A*0101-specific CD8(+) T cells can reach higher numbers than those used by CD8(+) T cells targeting various pp65 peptides in our patient cohort. This merits further investigation into the effectiveness of the different CMV-specific T cells and their impact on immunosenescence, which is important to eventually define the most useful source of adoptive therapy and monitoring protocols for cytomegalovirus-specific immune responses.

Flow cytometry assessment of apoptotic CD34+ cells by annexin V labeling may improve prediction of cord blood potency for engraftment.

BACKGROUND: Nonviable CD34+ cells are commonly assessed by standard flow cytometry using the nuclear stain 7-aminoactinomycin D (7AAD). 7AAD, however, only detects necrotic and late apoptotic cells, not earlier apoptosis, which engraft poorly in animal models of cord blood (cord) transplantation. The standard method, therefore, may overestimate engraftment potency of cord units under certain conditions. STUDY DESIGN AND METHODS: To detect apoptotic events, costaining with 7AAD and annexin V (AnnV), in parallel with the quantitative, standard enumeration, was used. Cord units were assessed before and after cryopreservation using both staining methods and colony-forming units (CFU) to determine if graft potency can be predicted using a "functional flow cytometry" approach. RESULTS: Significant numbers of CD34+ AnnV+ events were found within the 7AAD-gated population. Nonapoptotic cell dose (CD34+ AnnV-) correlated well with CFUs in both a small-scale (n = 10) and a large-scale banking study (n = 107). Finally, following samples postthaw with time showed increasing numbers of apoptotic CD34+ cells and consequently the AnnV assessed dose was better at predicting the CFU compared with just the standard enumeration. CONCLUSION: Defining the apoptotic population of CD34+ cells improved the prediction of CFU, making this method a rapid test of potency for assessment of cord units for clinical use.

Transforming growth factor-ß1 polymorphisms and the outcome of hematopoietic stem cell transplantation.

Hematopoietic stem cell transplantation (HSCT) is a medical procedure used to treat malignant and nonmalignant haematological diseases, congenital immunodeficiency syndromes, solid tumours and metabolic diseases. Despite its usefulness, several major complications, such as graft-versus-host disease, can negatively affect patients treated with HSCT. Apart from clinical factors well known to affect the outcome of HSCT, patient and donor genetics have been shown to play an important role in the susceptibility to post-transplant complications. Histocompatibility as determined by the human leucocyte antigen (HLA) system has been a major genetic determinant of the success of HSCT. Non-HLA immunogenetics are increasingly recognized to play a part in the events related to transplantation. Cytokine genes, and their receptors, bear a considerable amount of polymorphism. One of the genes that may play an important role on the outcome of allogeneic HSCT is TGFB1, which encodes transforming growth factor, ßeta 1 (TGF-ß1). TGF-ß1 is a pleiotropic cytokine, which plays a central role in the development, homeostasis and responses of the immune system. Several functional polymorphisms in TGFB1 have been identified, and these are known to cause alterations in cytokine secretion in several settings. The present review will focus on the current knowledge surrounding the effect of polymorphisms within TGFB1 on the outcome of HSCT.

Advanced Cell Therapy: Beyond the last Frontier in the Treatment of Cancer. A Historical Perspective Emphasizing the Work of Nobel Prize Laureates.

During the last five decades different therapies have been developed for the treatment of cancer, and as a result, patients can now live longer and better lives. Among such therapies, hematopoietic cell transplantation and immunotherapy have played key roles. In this short article, we present our particular point of view on the development of these two cellular therapies. We have focused on a historical perspective emphasizing the work of some of the Nobel Prize winners whose studies constituted cornerstones in our knowledge of the biology of cancer and in our fight against this devastating disease.

Unrelated donor peripheral blood stem cell transplants incorporating pre-transplant in-vivo alemtuzumab are not associated with any increased risk of significant acute or chronic graft-versus-host disease.

There is little information published comparing peripheral blood stem cells (PBSC) with bone marrow (BM) as the stem cell source in the long-term outcome in recipients of T-cell depleted (TCD) unrelated donor (UD) transplants. We present retrospective outcome data on 306 recipients of myeloablative, human leucocyte antigen-matched UD allografts using pre-transplant in-vivo Alemtuzumab. Transplants were performed between 2000 and 2007 for chronic myeloid leukaemia in first chronic phase and acute leukaemia in first or second complete remission; 184 patients received BM and 122 PBSC. The median age was 28·9 years (<1-58) and the median follow-up was 48 months. Overall survival at 8 years was 53%. The incidence of acute graft-versus-host disease (GvHD) was significantly higher in PBSC (65%) than BM recipients (49%; P=0·012). This represented only grade 1 GvHD with no difference in grade II-IV aGvHD (BM 23% PBSC 24%). The incidence of chronic GvHD, either overall (BM 47%, PBSC 49%) or extensive (BM 15%, PBSC 13%) was not increased with PBSC. The incidence of relapse, non-relapse mortality and survival were not significantly different. Whilst accepting the limitations of retrospective analyses, we suggest the increased risk of GvHD in recipients of PBSC in T-replete transplants is offset by in-vivo Alemtuzumab, and that either stem cell source can be used with good outcomes in this setting.

The impact of HLA genotyping on survival following unrelated donor haematopoietic stem cell transplantation.

One of the major factors that have contributed to improving the outcomes of Stem Cell Transplantation is progress made in the field of human leucocyte antigen(s) (HLA). This is evident not only in developing techniques for rapid and accurate tissue typing, but also in the greatly improved understanding of the HLA system and the impact of HLA matching on transplant complications. It is now accepted that high-resolution HLA matching for transplant recipients and unrelated donors is associated with the best clinical outcomes. The most important HLA determinants are the six 'classical' polymorphic HLA loci: HLA-A, -B, -C, -DRB1,-DQB1, -DPB1. For several years, based on the outcome of numerous studies, a 10/10 matched donor (HLA-A, -B, -C, -DRB1, -DQB1) was considered the ideal. The impact of HLA-DPB1 has been less clear, in view of reduced likelihood of patient/donor matching for this locus. More recently, several large studies have questioned the importance of HLA-DQB1 matching on outcome. Based on the findings of recent studies, the current gold standard unrelated donor is believed to be one matched for 8/8 alleles at high resolution i.e. matched for HLA-A, -B, -C, -DRB1, however, in certain circumstances, mismatches may be tolerated and/or permissive.