T-cell Replete Transplantation Research Articles

Feasibility of Cyclosporine a Instead of Tacrolimus after Haploidentical Transplantation Using PBSC Grafts with Post-Transplant Cyclophosphamide for Hematological Malignancies

Introduction T cell replete Haploidentical transplants have usually employed Tacrolimus and Mycophenolate Moefetil as the GVHD prophylaxis with Post-transplant cyclophosphamide(PTCy). Cyclosporine A(CsA) has been successfully utilized earlier in place of Tacrolimus with this strategy. Injectable tacrolimus is not available in India so we considered replacing it with injectable Cyclosporine A. In this retrospective analysis we describe our initial experience with the above strategy. Objectives To assess the feasibility of using intravenous Cyclosporine A with PBSC and PTCy in T-cell replete transplantation for hematological malignancies. Methods From April 2017 to July 2019, 13 patients underwent 14 such transplants, median age 30 years (1-56) for various hematological malignancies AML-6, ALL-3, MPAL-1,CML-BC-4. 3 transplants were done in CR1, 4 in active disease and 7 in CR2. Conditioning used was Flu-Bu in 5 patients, Flu-Cy-TBI in 5 patients, Clofarabine(Clo)-Bu in 1 patient, Clo-Mel-TBI in 2 patients and Bu-Mel in 1 patient. Intravenous CsA and MMF were started 24 hours after PTCy. CsA trough levels were monitored thrice weekly to target level of 200-300 µg/L. Results All patients except one successfully engrafted at a median of 15.5 days (13-25). At a median follow up of 8 months (2-28 months) the relapse-free suvival was 65.4% while the overall survival was 68%. There were 4 relapses in 3 patients. 2 relapses occurred in patients transplanted in active disease (AML). Grade 1-2 acute GVHD occurred in 28% while grade 1-2 chronic GVHD occurred in 21.4% patients. No patient developed grade 3 or 4 GVHD. There were no treatment related deaths. Conclusion CsA is a feasible option in place of Tacrolimus in T cell replete haploidentical transplantation for hematological malignancies and has an acceptable outcome.

Clinical Determinants of T-Cell Receptor Diversity after Allogeneic Hematopoietic Stem Cell Transplantation for Acute Myeloid Leukemia

T-cell reconstitution after allogeneic haematopoietic stem cell transplantation (alloSCT) is critical for protection against infection and to mediate the graft versus leukemia (GVL) effect against hematological malignancies including acute myeloid leukemia (AML). T-cell reconstitution post-alloSCT is significantly impacted by exogenous factors including T-cell depleting strategies, immunosuppressive medications and the prohibitive effects of graft versus host disease (GVHD) and infection. The early T-cell repertoire post-alloSCT is oligoclonal and clinical events such as infection and GVHD may adversely impact recovery of a diverse TCR repertoire. The objectives of this study were to investigate clinical determinants of TCR diversity at day 100 after alloSCT and the impact of TCR diversity on risk of early AML relapse after alloSCT. Methods Twenty-nine patients who underwent HLA-matched sibling or unrelated donor alloSCT were included in this cohort comprising 16 patients with AML relapse at day 100 to 180 post-alloSCT and 13 control patients who did not relapse post-alloSCT. All patients received unmanipulated peripheral blood or bone marrow stem cells. Anti-thymocyte globulin was administered to all patients receiving unrelated donor stem cells as per institutional practice. Surveillance for cytomegalovirus (CMV) viremia in peripheral blood (plasma) was monitored twice weekly using polymerase chain reaction (PCR) and pre-emptive therapy with intravenous ganciclovir or oral valganciclovir was commenced in patients with plasma viral load of 400 copies/mL or greater. Peripheral blood samples were obtained at day 100 (early time-point). Eleven patients had follow-up samples 1-2 years post-transplant (late time-point). T-cells were isolated using immunomagnetic separation. Following DNA extraction, TCRβ loci deep amplicon sequencing was performed using LymphoTrack TRB. Sequence assembly, annotation and error correction was performed by MiXCR. TCR diversity was quantified using inverse Simpson's diversity index (1/D). Results TCRβ sequencing of the entire cohort of 29 patients was performed with a mean of 454516 sequence reads per patient. Median time from transplant for the early post-alloSCT timepoint was 99 days. Median TCR repertoire diversity (1/D) early post-transplant was 104.3 (IQR 46.5-398.4). TCR diversity was significantly greater in patients who received T-cell replete transplants from matched sibling donors compared with T-cell depleted transplants from unrelated donors (siblings 130.1 [IQR 54-1017] vs unrelated donors 64 [IQR 28.9-96.9]; P=0.04). Early TCR diversity was significantly reduced in recipients who were CMV seropositive prior to transplant compared with seronegative patients (77.5 [IQR 42.4-127.5] vs 718.8 [IQR 75.5-1884]; P=0.01). Twenty patients (69%) developed CMV viremia, defined as any detectable CMV virus in peripheral blood, prior to day 100 post-alloSCT. Early TCR diversity was significantly reduced in patients with CMV viremia within the first 100 days post-alloSCT (83.5 [IQR 42.4-131.5] vs 964.4 [IQR 71.7-2399]; P=0.02). There was no significant difference in TCR diversity at day 100 in patients who had prior acute GVHD compared to those who did not. There was no significant difference in early TCR diversity at the time of AML relapse compared with patients who remained in remission (78.4 [IQR 38-799.2] vs 132.8 [IQR 59.5-753.6]; P=0.22), suggesting that a restricted TCR repertoire early post-transplant is not a mechanism of AML relapse. Eleven patients had serial samples analysed at early (day 100) and late (between 1-2 years post-transplant) timepoints. All patients remained free of leukemia relapse between these two timepoints. Patients with early CMV viremia (prior to day 100) continued to have a significantly reduced TCR diversity late post-transplant compared with patients who did not have early CMV reactivation (33.2 [IQR 27.3-61.4] vs 3868 [IQR 1421-4565]; P=0.006), indicating that early CMV viremia had a persistent effect on post-transplant T-cell recovery extending to 1-2 years post-transplant. Conclusion T-cell depletion and CMV viremia are key determinants of early TCR repertoire diversity post-alloSCT. CMV viremia has persistent and deleterious effects on TCR repertoire late post-transplant. TCR diversity does not impact early AML relapse post-alloSCT. Disclosures Ritchie: Amgen: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy; BMS: Research Funding; Takeda: Research Funding; Beigene: Research Funding; Imago: Research Funding; Novartis: Honoraria; Sanofi: Honoraria. Koldej:NanoString Technologies: Other: Travel grant. Blombery:Novartis: Consultancy; Janssen: Honoraria; Invivoscribe: Honoraria.

Low-dose post-transplant cyclophosphamide can mitigate GVHD and enhance the G-CSF/ATG induced GVHD protective activity and improve haploidentical transplant outcomes

ABSTRACTUse of high-dose, post-transplant cyclophosphamide (PTCy) results in low rates of graft-versus-host-disease (GVHD) and favorable immune reconstitution, although with higher rates of relapse and somewhat high rates of graft failure. We hypothesized that permissible dose reduction of PTCy might be feasible. The current study attempts to establish a murine model and focus on regulatory T cells (Tregs) to clarify the immunological mechanisms for GVHD prevention by low-dose PTCy. In addition, a prospective, clinical cohort study in haploidentical, T-cell replete transplantation is initiated to support the rational. We found that acute GVHD could be alleviated by low-dose PTCy and could be further mitigated after the combined use of low-dose PTCy and antithymocyte globulin (ATG) in mice. Flow-cytometric analyses in mice showed that low-dose PTCy could increase the number of Tregs and the effect on Tregs is significantly prominent with the combined use of low-dose PTCy and ATG. In the clinical cohort study, the cumulative incidence of grades II-IV acute GVHD in combined treatment cohort with low-dose PTCy and ATG/granulocyte colony-stimulating factor (G-CSF) (17%; 95% CI, 5–29%) was significantly lower than both that in matched-pair cohort (33%; 95% CI, 25–41%; P = 0.04) and that in historical cohort (56%; 95% CI, 42–70%; P < 0.001). In-vivo immune reconstitution analysis showed that low-dose PTCy could facilitate suppressive Tregs reconstitution. In conclusion, low-dose PTCy is sufficient for GVHD abrogation under lymphopenic situation and can enhance the protective effect of ATG/G-CSF on GVHD. Intensified conditioning followed by low-dose PTCy might be a feasible option for patients undergoing haploidentical transplantation.

JC Virus and Progressive Multifocal Leukoencephalopathy After Haplo-Identical T-Cell Replete Transplantation with Post-Infusion Cyclophosphamide Recipient

JC Virus and Progressive Multifocal Leukoencephalopathy After Haplo-Identical T-Cell Replete Transplantation with Post-Infusion Cyclophosphamide Recipient

Haploidentical T-cell replete transplantation with post-transplant cyclophosphamide or matched unrelated donor for patients with high-risk hematologic malignancies? A single-center experience

S80 2.134, 95% CI [1.186-3.843]) and 2) chronic GVHD development, 10.2% vs 1.4% (p1⁄40.0002, HR 5.762, 95% CI [2.289-14.510]). Incidence of AVN was 15.7% in patients with moderate to severe grade chronic GVHD and 3.6% in those with mild grade GVHD(p1⁄40.00015). A risk score model was generated assigning 1 score to each risk factor and summing the score thus dividing into three groups: low(score 0, n1⁄4349, 41.3%), intermediate (score 1, n1⁄4379, 44.9%) and high risk (score 2; n1⁄4116, 13.7%). This risk score could stratify the patients according to AVN risk (p1⁄42.49x10). The risk of AVN was 1.5% (0.5-3.6%) in low, 6.2% (3.7-9.5%) in intermediate and 20.8% (13.0-29.9%) in high risk group. Conclusions: Moderate/ severe grade of chronic GVHD and younger age ( 45 years old) are key risk factors for AVN following allogeneic HCT.

Impact Of Female Donor On Allogeneic Stem Cell Transplantation Outcome Of Male Recipient After T-Cell Depletion By Rabbit Antithymocyte Globulin

The female donor/male recipient combination (FM) increases the risks of graft-versus-host disease (GVHD) and non-relapse mortality (NRM) after allogeneic stem cell transplantation (allo-SCT), with a possible deleterious impact on overall survival (OS) [Gahrton G. Best Pract Res Clin Haematol. 2007 Jun;20(2):219-29]. Most patients in these studies received T-cell replete transplants. As a consequence, and because antithymocyte globulin (ATG) reduces the risk of GVHD, the impact of FM in the specific setting of allo-SCT with ATG remains poorly defined.To explore the impact of FM in the ATG setting, we undertook a retrospective analysis of male adult patients transplanted with rabbit ATG at our center between 01/01/2000 and 12/31/2012. Overall survival and disease-free survival (DFS) were calculated using the Kaplan-Meier estimate, with comparisons by the log-rank test. Cumulative incidences (CI) were used for NRM, relapse (REL), and GVHD in a competing risks setting, NRM being a competing event for REL, and death for GVHD. The Gray test was used to compare CI curves. For multivariate analysis, the variables with p value < 0.1 were entered into a Fine-Gray model where the least significant variables were excluded in sequential fashion until all remaining factors were significant at the p=0.05 level. The following variables were considered: recipient age (≥ vs < 56 years, median age), female donor (FD) vs male donor (MD), matched related (MRD) vs matched unrelated (MUD) donor, peripheral blood (PB) vs bone marrow (BM) graft, GVHD prophylaxis with cyclosporine (CsA)+metho vs others, myeloablative (MAC) vs reduced-intensity conditioning (RIC) regimen, CMV-seropositive vs seronegative recipient, early (CR1 or PR1 or chronic phase or untreated) vs advanced disease. Steroid-refractory (SR) acute (a) GVHD was defined as aGVHD progressing after 3 days of treatment, or unchanged after 7 days, or in incomplete response after 14 days. MUD were matched at the allele level for HLA-A, B, C, DRB1, DQB1.Two hundred and twelve male patients were identified and included in the present study. The median age was 56 years (18-67). Diseases were AML (n=61), ALL (n=16), NHL (n=36), Hodgkin's disease (n=10), myeloma (n=37), MDS (n=26), aplastic anemia (n=7), CLL (n=11), CML (n=1), and MPS (n=7). Status at transplant were CR1 or PR1 or chronic phase (n=74), > CR1 or PR1 (n=83), refractory (n=34), or untreated (n=21). Conditioning regimens were RIC (n=195) or MAC (n=17). Donors were MRD (n=110) or MUD (n=102). Eighty-eight patients were transplanted with a FD. Source of stem cells were PB (n=193), BM (n=18), missing data (n=1). Prophylaxis of GVHD consisted of CsA+metho for 84 patients.The median follow-up was 42 months (5-149). In univariate analysis, the 3-year OS and DFS in FD vs MD groups were 48% ± 6% vs 56% ± 5% (p=0.3) and 42% ± 5% vs 50% ± 5% (p=0.4), respectively. The 3-year NRM and REL in the same groups were 25% ± 5% vs 19.6% ± 4% (p=0.4) and 30% ± 5% vs 31% ± 4% (p=0.9), respectively. The CI of aGVHD II-IV, aGVHD III-IV, SR aGVHD, and extensive chronic GVHD in FD vs MD groups were 37.5% ± 5% vs 33% ± 4% (p=0.5), 22.7% ± 4% vs 17% ± 3% (p=0.3), 17.2% ± 4% vs 8.3% ± 3% (p=0.049), and 20% ± 4% vs 22.5% ± 4% (p=0.9), respectively. Other variables considered in univariate analysis for SR aGVHD were recipient age (p=0.9), recipient CMV status (p=0.7), disease status (p=0.9), RIC vs MAC (p=0.16), MRD vs MUD (p=0.09), PB vs BM graft (p=0.4), and GVHD prophylaxis (p=0.2). In multivariate analysis, the risk factors for SR aGVHD were FD (HR=3.1, 95%CI: 1.2-7.9, p=0.01) and MUD (HR=2.9, 95%CI: 1.1-7.1, p=0.02). The CI of SR aGVHD were 32.3% ± 9.7% in the FD + MUD group (n=29), 9.7% ± 3.8% in the MD + MUD group (n=73), 10.7% ± 4.1% in the FD + MRD group (n=59), and 6.5% ± 3.7% in the MD + MRD group (n=51); p=0.004.We conclude that FD was an independent risk factor for SR aGVHD after allo-SCT with rabbit ATG in male adult patients mostly transplanted with PB after RIC. There was no impact of FD on aGVHD II-IV or III-IV, chronic GVHD, NRM, REL or survival. Finally, the absence of impact of FD on NRM and survival should be interpreted with caution given the retrospective design of the study and because we cannot exclude a possible limiting effect of an insufficient number of patients. Disclosures:No relevant conflicts of interest to declare.

Predominant or complete recipient T-cell chimerism following alemtuzumab-based allogeneic transplantation is reversed by donor lymphocytes and not associated with graft failure

The clinical significance of mixed chimerism following allogeneic haematopoietic stem cell transplantation (HSCT) remains controversial. Its relevance and incidence are probably influenced by the conditioning regimen and incorporation of T-cell depletion. The presence of recipient chimerism levels >40-50% following T-cell replete reduced intensity transplantation correlates with a high risk of graft rejection, regardless of donor-lymphocyte infusions, but it is unclear whether this finding translates to T-cell depleted transplants. We conducted a retrospective single-institution analysis of patients receiving alemtuzumab-based HSCT. 27/152 (18%) evaluable cases had predominantly recipient T-cell chimerism at 3 months or beyond. By contrast, coincident chimerism in the granulocyte lineage was predominantly of donor origin (median 100%) in all but one patient. Donor lymphocyte infusion effectively converted predominantly recipient T-cell chimerism to ful donor chimerism in all evaluable cases including three cases with no detectable donor T cells. The only graft failure occurred in the patient with predominantly recipient myeloid chimerism in whom rejection occurred rapidly before donor lymphocytes could be administered. We conclude that predominant or complete recipient T-cell chimerism following alemtuzumab-based regimens does not have the same clinical implications as that following T-cell replete transplants and can be effectively converted with donor lymphocytes without the need for lympho-depleting agents or re-conditioning.

NK cell education after allogeneic transplantation: dissociation between recovery of cytokine-producing and cytotoxic functions

AbstractNatural killer (NK) cells mediate GVL effects after allogeneic hematopoietic cell transplantation (allo-HCT) by the production of inflammatory cytokines and by direct target lysis. The acquisition of both functions was presumed to be developmentally linked, but this linkage remained unstudied after allo-HCT. We tested the cytokine production and degranulation of reconstituting NK cells after adult unrelated donor or umbilical cord blood grafting. Recipients of T cell–depleted transplants, receiving no immune suppression, showed diminished NK cell degranulation. In contrast, degranulation was normal or increased after T-cell replete transplants given with immune suppression. Strikingly, target cell-induced IFNγ production was markedly diminished in all transplant settings, especially with T cell–depleted or naive T cell–containing umbilical cord blood grafts, suggesting a role for T cells in NK education. Although degranulation was similar in the KIR+ and KIR− populations that coexpressed NKG2A, target cell-induced IFNγ production was limited to the subset of NK cells expressing KIR inhibited by self-ligands. Thus, cytokine production and cytotoxic function do not consistently coexist in NK cells reconstituting after allo-HCT. Exposure to IL-15 rapidly increased target-inducible IFNγ production, indicative of IL-15's potential as a therapeutic tool to enhance NK cell function to protect against infection and relapse after allo-HCT.

Lymphocyte subset recovery and outcome after T-cell replete allogeneic hematopoietic SCT

Rapid recovery of lymphocytes after T-cell depleted hematopoietic SCT (HSCT) protects from relapse of myeloid malignancies. Whether lymphocyte reconstitution has a similar role after non-manipulated transplantation is controversial. We assessed numbers of CD4 and CD8 T-cells, natural killer (NK) cells and B-cells, before and 1, 3, 6, 12 and 24 months after T-cell replete transplantation in 345 patients. Lymphocyte subset counts up to 6 months post transplant had no effect on relapse. Elevated number of NK cells 12 months post transplant protected from relapse. As a novel finding, early recovery of NK cells was associated with significant protection from TRM already at the 3 and 6 months time points (P=0.03, P=0.02). In Cox multivariable models, patients with NK cells above 150/μL were significantly protected from TRM (hazard ratio (HR) 0.45, 95% confidence interval (95% CI) 0.21-0.95, P=0.03), an effect comparable in magnitude with that of carrying >200 CD4 T-cells/μL (HR 0.37, 95% CI 0.19-0.74, P=0.005). CD8 T-cell and B-cell recovery did not affect the rates of relapse or TRM. Early reconstitution of NK cells and CD4 T-cells in patients undergoing T-cell replete HSCT independently protected from TRM. Only a weak protection from disease relapse was noted for patients with high numbers of NK cells, and this occurred only late after transplantation.

CMV-Specific T Cell Immunotherapy Promotes Restoration of Durable Functional Immunity in High Risk Patients Following Allogeneic Stem Cell Transplantation

Adoptive cellular therapy with virus-specific T-cells offers the potential for accelerating pathogen-specific immune reconstitution, thus limiting the morbidity and mortality of viral infections following allogeneic haematopoietic stem cell transplantation (aHSCT). However, the logistics of production and the risk of inducing graft-versus-host disease (GvHD) secondary to the infusion of alloreactive clones have restricted their application. We examined the use of polyclonal cytomegalovirus (CMV)-specific mixed CD4+ and CD8+ T-cell lines, generated by short-term ex vivo culture of donor lymphocytes with donor monocyte-derived dendritic cells pulsed with virus-lysate. Following initial evaluation in a phase I study of pre-emptive cellular therapy in mainly matched related donor transplant recipients, we performed a phase I-II study including a higher risk population routinely receiving CMV-specific T cells 28 days following transplantation. Thirty patients received CMV-specific T cells in this study. The majority were at high risk of viral infection, being CMV seropositive recipients (24/30), having received a T-cell depleted graft (24/30), and/or having an unrelated or mismatched donor (14/30). T cell lines were administered prior to viral DNA detection (prophylaxis) in 10 patients, following a single viral DNA detection episode (pre-emptive) in 10 and concurrent with antiviral drug therapy in 10. There were no significant immediate toxicities. Acute GvHD > Grade I occurred in 2/24 T-cell depleted transplants (1 Grade II, 1 Grade III), and 2/6 T-cell replete transplants (2 Grade III), but in 0/14 unrelated or mismatched donor transplants, suggesting no excess of GvHD associated with cellular therapy. Only 3/10 treated prophylactically developed CMV infection requiring therapy (2 following introduction of systemic steroids). All 10 receiving cells pre-emptively required antiviral drugs. CMV-specific immune reconstitution was monitored using class I HLA-pentamers restricted by HLA-A*0201 (the NLV epitope of pp65, and the VLE epitope of IE-1) and HLA-B*0702 (the TPR and RPH epitopes of pp65). In vivo expansions of hCMV-specific T-lymphocytes were observed within days to weeks of adoptive transfer and temporally associated with periods of viral replication. Peak pp65-directed responses following infection ranged between 6.7–43% of CD8+ T cells, with absolute levels of 60.2–371.5 × 106/l, well in excess of those previously reported to offer protection against CMV (10–20 × 106/l), whilst those in patients not experiencing viral DNAemia reached maximal levels of 0.5–0.8% of CD8+ T cells equivalent to absolute levels of 0.2–0.8 × 106/l. Assuming transfused cells are largely responsible for the increase in CMV-specific T cell numbers, at least in the T-cell depleted unrelated donor setting which is associated with markedly impaired immune reconstitution within the first 100 days following transplantation, we estimate that NLVspecific T cells were expanded up to 5 log over a period as short as 10 days following transfer (assuming a 5 litre circulating volume and that 2% of the lymphocyte pool is located in the peripheral blood) with lymphocyte doubling times possibly as low as every 12 hours. Expanding populations maintained functional competence in terms of ability to produce IFNγ in ex vivo restimulation assays (up to 77% of pentamer-labelling cells secreted IFNγ). Following a primary post-transplantation treatment episode 20 patients were evaluable for subsequent viral infection. With a median follow-up of 953 days (range 250–1590) none developed a second episode requiring therapy (compared to 45/72 historical controls, P < 0.0001) and there were no cases of CMV disease. Combined with the absolute circulating levels attained and the functional competence of CMV-specific T cells following transfer, these data indicate that infusion of cell lines containing both CD4+ and CD8+ virus-specific T cells promotes reconstitution of durable functional CMV-specific immunity, effectively preventing recurrent viral infection and late CMV disease in a group of high risk aHSCT recipients.

A Comparison of Stem Cell Source in Recipients of T-Cell Depleted Myeloablative Transplants for Leukaemia: No Difference in Mortality Using BM or PBSC.

The use of GSCF-mobilised Peripheral Blood Stem Cells (PBSC) for unrelated donor (UD) transplantation has increased dramatically since 2000. The association of PBSC with more rapid engraftment and with an increase in chronic Graft versus Host Disease (GvHD), compared to bone marrow (BM) has been reported in a number of studies. More recently the use of PBSC has been associated with an increase in transplant related mortality (TRM) and decrease in survival (OS) in T-cell replete transplants. We sought to analyse the impact of PBSC compared to BM in a cohort of UD transplant recipients, where T-cell depleting agents (in-vivo campath in >90%) were included in the transplant conditioning. The study included 145 patients transplanted between January 2000 and March 2006: CML- 35 in 1CP; acute leukaemia (AML in 61, ALL in 49)-110 in CR1 or 2. All had myeloablative conditioning regimens and received grafts with 9–10/10 matched HLA alleles. 86 patients received BM and 59 PBSC. There were no associations between the stem cell source and any transplant variable (including disease and stage). There was a trend to an increased use of PBSC in patients with a single antigen mismatch (p=0.052). All evaluable patients achieved neutrophil engraftment, with a significantly faster time to engraft in recipients of PBSC compared to BM (16 vs 20 days; p=0.0003). The incidence of acute GvHD was 46% (grade I in 50%, II in 41%, III in 8%, IV in 2%). This was significantly higher in recipients of PBSC (60%) compared to BM (36%; p=0.006), however there was no increase in either II/IV (p=0.69) or III/IV (p=0.18) disease in PBSC recipients. In univariate analysis, the presence of a single HLA mismatch (p=0.026) was the only other variable to be associated with an increase in acute GvHD. In a logistic regression model including both these variables, the use of PBSC remained significantly associated with an increase in aGvHD (OR=2.3; 95% CI 1.1,4.7;p=0.020). The TRM was 14%, 27% and 39% at 100 days, 1 and 5 years respectively. At none of these time points was the stem cell source associated with a significant difference in TRM. The 5-year incidence of chronic GvHD was 58% (BM 55%, PBSC 60%; NS), extensive disease in one third, and of relapse was 61% (BM 60%, PBSC 62%; NS). The 5-years OS was 41% with a median follow-up of 3.4 years (0.5–7.1). This was 44% using PBSC and 40% using BM (NS). In conclusion, although we observed an increase in acute GVHD with PBSC this was only of grade 1 disease. We found no association between the use of PBSC and an increased risk of chronic GVHD or of a worse transplant outcome, when compared to BM, in recipients of T-cell depleted myeloablative transplants for leukaemia.

Activating KIR (B Haplotype) in Unrelated Donors Improves Disease-Free Survival after HLA-Matched and Mismatched Allogeneic Transplantation for Acute Myeloid Leukemia: Implications for Donor Selection Using KIR Genotyping.

The importance of killer immunoglobulin-like receptors (KIR) in determining clinical outcome after hematopoietic cell transplantation (HCT) remains controversial. We analyzed 428 unrelated, T-cell replete transplants for acute myeloid leukemia (AML) facilitated by the National Marrow Donor Program between 1988 and 2003. Fifty seven KIR-ligand mismatched (thus HLA mismatched; KIR-Lmm/HLAmm) transplants were selected as cases. By matching on 15 clinical and demographic variables, KIR ligand matched, HLA mismatched (KIR-Lm/HLAmm; n = 162) and 10/10 HLA matched (HLAm; n = 209) comparison groups were selected. Using a validated single nucleotide polymorphism (SNP)-based MALDI-TOF assay, DNA samples were typed for 16 individual KIR genes which were used to estimate KIR haplotypes. About 1/3 of donors and recipients were A/A (lacking any activating KIR except 2DS4) and 2/3 possessed at least one B haplotype (B/X). As expected, 3 year survival was better in HLAm vs. HLAmm KIR-Lm or KIR-Lmm HCT (32%; p = .07 and 0.0004 respectively). However, survival was similar in both HLAmm groups (KIR-Lm 27% vs. KIR-Lmm 17%; p = .11). Importantly, transplants from donors with an activating B KIR haplotype had significantly better survival. Using a Cox regression that stratifies the baseline hazard according to sets of patients matched on important clinical variables, transplants using B KIR haplotype donors had a 42% reduced risk of mortality [B/X (vs. A/A) KIR haplotype donors (RR .58, 95% CI .44–.78; p = .0002]. Similarly, for disease-free survival (DFS), the risk of relapse and/or death decreased 43% [B/X (vs. A/A) RR .57, 95% CI .43–.76; p = .0001]. No differences were seen in risks of acute GVHD. The significant improvements in overall survival and DFS conferred by donor B KIR haplotype were seen in both the HLAm and KIR-Lm/HLAmm groups, but not in the KIR-Lmm/HLAmm group. The recipient KIR haplotype had no effect on outcomes, and the benefit of donor B KIR haplotype was equal regardless of recipient KIR haplotype (figure). Individual KIR genes were also analyzed and in Cox regression only donor 2DL2 and 2DS2 were favorable. As these genes are in strong linkage disequilibrium, the effects were similar (donor 2DL2 RR of death .70, 95% CI .54–.91; p = .008 and 2DS2 RR .66, 95% CI .50–.86; p = .002). 2DS2 defines a B KIR haplotype, confounding interpretation of these single gene effects. In summary, data from this analysis of the effect of KIR genes in unrelated T-replete HCT for AML suggest that using B KIR haplotype donors improves survival and DFS. Therefore, KIR genotyping could be incorporated into unrelated donor selection algorithms to identify B haplotype donors for patients with AML. [Display omitted]

Influence of HLA-C Matching on aGvHD of Unrelated and Family Donor Hematopoietic Stem Cell Transplantation in Pediatric Patients with Hematologic Malignancies.

With a continuous decrease in family size, identification of an HLA identical sibling donor for allogeneic hematopoietic stem cell transplantation (HSCT) is often unsuccessful. High resolution HLA-Typing of HLA class I and II loci has opened new avenues for identification of the optimal unrelated donor. Yet, the role of HLA-C matching in HSCT remains controversial. This is particularly true for pediatric transplantation recipients in whom currently little data are available. Here we report on the role of HLA-C matching in a single center cohort of children aged 0–18 years (median: 9,6 years; n=32) who underwent HSCT from an unrelated (n=28) or non-sibling family (n=4) donor for hematopoietic malignancies with a typical disease distribution for pediatric transplant recipients (11 ALL, 6 AML, 8 MDS, 3 JMML, 3 CML, 1 NHL). Patients (pts) with acute leukemia not in remission were excluded from the study. Donor selection was performed prospectively on the basis of HLA A, B low resolution and DR, DQ high resolution-typing with 4 donors exhibiting an isolated HLA-A or -B MM. Donors mismatched for HLA-DRB1 and -DQB1 (n=2) were excluded from the evaluation. In retrospective analysis, the number of donors with additional 1–2 HLA-C antigen MM was high (12/32 pts, 38%). Upon evaluation of the influence of HLA-C MM on critical transplantation parameters, significant correlation between HLA-C MM and severe acute GvHD (aGvHD III–IV; p=0,012) was documented. Of 31 pts evaluable for aGvHD, 7/12 (58%) pts in the HLA-C-MM group suffered from severe aGvHD vs. 2/19 (10%) pts without an HLA-C MM. There was no correlation with severe aGvHD and patient age, sex, underlying disease, stem cell source nor HLA-C KIR epitope or HLA-A/B MM. While none of the 4 pts with isolated HLA-A/B MM showed severe aGVHD, 3/5 pts with combined HLA-A/B plus -C MM exhibited grade III–IV aGvHD. In those pts evaluable for chronic GvHD there was no difference between pts transplanted from an HLA-C MM vs. -matched donor. As in other studies, in our transplantation cohort, aGvHDIII–IV is significantly correlated with transplant-related mortality (TRM) with 6/9 (66%) pts with aGvHDIII–IV dead of complications vs. 3/23 (13%) with no or low grade aGvHD (p=0,007). Accordingly TRM is also increased in HLA-C MM pts with 5/12 (42%) pts vs 5/20 (25%) pts in the HLA-C matched group. High TRM is counterbalanced by a complete absence of relapses in the HLA-C MM group compared to 4/20 relapses in the HLA-C matched group resulting in comparable overall survival with 53+/−16% vs. 69+/−11% after a median observation time of 3.5 vs. 2.9 years, respectively (p=0.59). The high risk of GvHDIII–IV in pts. with HLA-C MM documents the necessity for HLA-C typing for optimal donor selection in T-cell replete transplants. Our data demonstrate that in a T cell-replete transplant setting, increased risk for severe aGvHD may neutralize the beneficial effect that an HLA-C-based KIR MM might have on the graft-versus-leukemia effect. In the absence of an ideally matched donor, awareness of the HLA-C constellation will assist with optimization of immunsuppressive prophylaxis.