Abstract

Administration of posttransplant cyclophosphamide (PTCy) has significantly expanded the number of patients undergoing HLA-haploidentical hematopoietic cell transplantation (haplo-HCT). To examine immune reconstitution in these patients, we monitored T- and natural killer (NK)-cell recovery in 60 patients receiving bone marrow or peripheral blood stem cell (PBSC) grafts after haplo-HCT with PTCy and 35 patients receiving HLA-matched donor PBSC grafts with standard graft-versus-host disease (GVHD) prophylaxis. Compared with HLA-matched recipients, early T-cell recovery was delayed in haplo-HCT patients and skewed toward effector memory T cells with markedly reduced naive T cells. We found higher regulatory T (Treg)-cell/conventional T (Tcon)-cell ratios early after HCT and increased PD-1 expression on memory T cells. Within the haplo-HCT, patients who did not develop chronic GVHD (cGVHD) had higher PD-1 expression on central and effector memory CD4+ Treg cells at 1 month after transplant. These findings suggest an immunologic milieu that promotes immune tolerance in haplo-HCT patients. NK cells were decreased early after haplo-HCT with preferential expansion of immature CD56brightCD16- NK cells compared with matched donor transplants. One month after transplant, mass cytometry revealed enrichment of immature NK-cell metaclusters with high NKG2A, low CD57, and low killer-cell immunoglobulin-like receptor expression after haplo-HCT, which partially recovered 3 months post-HCT. At 2 months, immature NK cells from both groups were functionally impaired, but interleukin-15 priming corrected these defects in vitro. Increased immature/mature NK-cell ratios were associated with cytomegalovirus reactivation and increased incidence of cGVHD after haplo-HCT. These homeostatic imbalances in T- and NK-cell reconstitution after haplo-HCT reveal opportunities for early immune-based interventions to optimize clinical outcomes.

Abstract

Allogeneic hematopoietic cell transplantation (alloHCT) can cure previously treated high-risk chronic lymphocytic leukemia (CLL) patients if they are suitable for transplant through the graft-versus-leukemia effect. However, since the emergence of targeted therapies, the role of alloHCT for high-risk CLL is less clear. To address this question, we evaluated 108 high-risk CLL patients who underwent alloHCT from 2010 to 2018. Thirty patients from the period of 2013 to 2018 received targeted therapy prior to alloHCT. The median age for the targeted therapy cohort was 60 years (range, 30-71 years), and 20% and 73% had complete and partial remission, respectively: 76% had del(17p), 46.2% had 5 or more cytogenetic abnormalities, and 78.9% were IGHV unmutated. The median number of prior therapies was 4 (range, 1-9). With a median follow-up time of 36 months (range, 10-72 months), the 3-year overall (OS) and progression-free survival (PFS) were 87% and 69%, respectively. The 3-year cumulative incidence of nonrelapse mortality and relapse was 7% and 24%, respectively. For the control cohort of 78 patients who underwent alloHCT from 2010 to 2014 and received only chemoimmunotherapy prior to transplant, the 3-year OS and PFS were 69% and 58%, respectively. Patients treated with targeted therapy prior to alloHCT had a significantly higher number of circulating T and B cells and a lower ratio of CD4 regulatory T cells to CD4 conventional T cells early after transplant. In summary, despite multiple high-risk features, the clinical outcome of CLL patients who receive targeted therapy prior to transplant is excellent and alloHCT should be offered while the disease is under control.

Abstract

We retrospectively analyzed outcomes in patients with acute myeloid leukemia (AML) receiving reduced intensity conditioning (RIC) hematopoietic stem cell transplants (HCT) from a peripheral blood (PB) source. We identified 46 haploidentical HCT (haplo), 59 matched unrelated donor HCT (MUD), and 40 matched related donor HCT (SIB) patients at a single institution. Haplo had improved overall survival (OS) when compared to MUD, HR 2.03 (p=0.01) but not SIB, HR 1.17, (p=0.61). There were no differences in relapse rates or treatment related mortality (TRM). Haplo had higher rates of acute graft versus host disease (GVHD) grade II-IV at day 180 than MUD (44% vs 25%, p=0.03) and SIB (44% vs 13% p<0.01). Rates of acute GVHD III-IV and chronic GVHD were similar among the groups. Haplo had slower engraftment rates compared to MUD with neutrophil engraftment at 87% vs 93%, (p<0.01) and platelet engraftment at 59% vs 86%, (p<0.01) at 28 days. Although patients receiving haplo had higher acute GVHD II-IV and slower engraftment, they did not have increased TRM. These data may suggest that patients receiving haplo have improved OS compared to MUD for AML patients receiving RIC transplants. This should be confirmed using a larger cohort.

Abstract

While hematopoietic cell transplant from an HLA-matched unrelated donor is potentially curative for hematologic malignancy, survival is lower for African Americans compared to Caucasians. As only about 20% of African Americans will have an HLA-matched unrelated donor many of these patients undergo HLA-haploidentical relative or umbilical cord blood transplantation. Thus, the current analyses studied transplant-outcomes after HLA-haploidentical relative (n=249) and umbilical cord blood (n=118) transplants for African Americans with hematologic malignancy between 2008 and 2016. The predominant disease was acute myeloid leukemia for both donor types. Grade II-IV and III-IV acute graft versus host disease was higher after umbilical cord blood (56% and 29%, respectively) compared to HLA-haploidentical relative transplantation (33% and 11%), p<0.0001. The 2-year incidence of transplant-related mortality adjusted for age and conditioning regimen intensity was higher after umbilical cord blood compared to HLA-haploidentical relative transplantation (31% versus 18%, p=0.008). However, there were no differences in the 2-year adjusted incidence of relapse (30% versus 34%, p=0.51), overall survival (54% versus 57%, p=0.66), or disease-free survival (43% versus 47%, p=0.46). HLA-haploidentical and umbilical cord blood extend access to transplantation with comparable leukemia-free and overall survival for African Americans with hematologic malignancy.

Abstract

Clinical disease caused by BK virus reactivation is a frequent complication of allogeneic hematopoietic cell transplantation (HCT). Because of the lack of effective antiviral agents, BK virus-specific T cells are emerging as a potential therapy for BK virus disease, but the immune response to BK virus after allogeneic HCT has not been well characterized. Our study describes reconstitution of BK virus-specific T-cell immunity in 77 adult patients after HCT. All patients had urinary symptoms, and urine was tested for BK virus replication; 33 patients were positive for BK virus (cases), and 44 were negative (controls). In BK virus cases, the median time to first positive test was 75 days (range, 2-511). BK virus cases had lower CD4 T-cell counts 3 to 9 months after transplant, but CD8 T-cell counts were similar in cases and controls. BK virus-specific T cells were identified by cytokine flow cytometry in cryopreserved samples collected prospectively. BK virus-specific CD4 T cells producing T helper 1 (Th1) cytokines recovered quickly after HCT. BK virus-specific T cells were detected more frequently in patients with BK virus reactivation at most time points, and CD4 T cells producing Th1 cytokines were more frequent than BK virus-specific cytolytic CD8 T cells. Early detection of interferon-gamma+ and cytolytic BK virus-specific CD4 T cells was associated with lower rates of hematuria among cases. Overall, our study describes recovery of BK virus-specific T cells after HCT and the distinct roles for BK virus-specific T cells in the development and resolution of clinical symptoms.

Abstract

Post-transplant cyclophosphamide (PTCy) has significantly increased the successful use of haploidentical donors with relatively low incidence of GVHD. Given its increasing use, we sought to determine risk factors for GVHD after haploidentical hematopoietic cell transplantation (haploHCT) using PTCy. Data from the Center for International Blood and Marrow Transplant Research on adult patients with AML, ALL, MDS, or CML who underwent PTCy-based haploHCT (2013-2016) were analyzed and categorized into 4 groups based on myeloablative (MA) or reduced intensity (RIC) conditioning and bone marrow (BM) or peripheral blood (PB) graft source. 646 patients were identified (MA-BM=79, MA-PB=183, RIC-BM=192, RIC-PB=192). The incidence of grade 2-4 aGVHD at 6 months was highest in MA-PB (44%), followed by RIC-PB (36%), MA-BM (36%), and RIC-BM (30%) (p=0.002). The incidence of chronic GVHD at 1 year was 40%, 34%, 24%, and 20%, respectively (p<0.001). In multivariable analysis, there was no impact of stem cell source or conditioning regimen on grade 2-4 acute GVHD; however, older donor age (30-49 versus <29 years) was significantly associated with higher rates of grade 2-4 acute GVHD (HR 1.53, 95% CI 1.11-2.12, p=0.01). In contrast, PB compared to BM as a stem cell source was a significant risk factor for the development of chronic GVHD (HR 1.70, 95% CI 1.11-2.62, p=0.01) in the RIC setting. There were no differences in relapse or overall survival between groups. Donor age and graft source are risk factors for acute and chronic GVHD, respectively, after PTCy-based haploHCT. Our results indicate that in RIC haploHCT, the risk of chronic GVHD is higher with PB stem cells, without any difference in relapse or overall survival.

Abstract

The a4ß7 integrin is upregulated on naive and memory T cell subsets in patients who subsequently develop gastrointestinal (GI) acute GVHD. Natalizumab (Tysabri(®), Biogen Inc.) acts against the a4 subunit that mediates homing of lymphocytes to the GI tract. We initiated a phase II study of natalizumab with corticosteroids for initial treatment of acute GI GVHD. In total, 300?mg IV of natalizumab was given, with steroids initiated up to 3 days prior. Twenty-one subjects were treated, median age was 63 years (range 38-74), and 15 (71%) were male. Eighteen (86%) underwent RIC, 15 (71%) received MUD, and all received PBSCs. Overall GVHD at enrollment was grade II in 4 and grade III in 17. The primary endpoint, day 56 GVHD-free survival rate, was attained in 33.3%. The overall response rate at day 28 and 56 was 57% and 52%, respectively. Six of eight CRs were durable for 1 year. Five experienced toxicity possibly related to natalizumab and ten had infections before day 100. 2-year OS was 43% (95% CI 22-62%) and 2-year NRM was 52% (95% CI 29-71%). Natalizumab with corticosteroids as initial treatment of acute GI GVHD is safe, effective, and durable.

Abstract

We sought to study whether survival after haplo-identical transplantation is comparable to that after matched unrelated donor transplantation for 822 patients aged 50-75 years with acute myeloid leukemia in first or second complete remission. One hundred and ninety-two patients received grafts from haplo-identical donors (sibling 25%; offspring 75%) and 631 patients from matched unrelated donors aged 18-40 years. Patient and disease characteristics of the two groups were similar except recipients of matched unrelated donor transplantation were more likely to have poor risk cytogenetics and more likely to receive myeloablative conditioning regimens. Time from documented remission to transplant did not differ by donor type. Five-year overall survival was 32% and 42% after haplo-identical and matched unrelated donor transplant, respectively (p-value=0.1). Multivariable analysis showed higher mortality (hazard ratio 1.27, p-value=0.04) and relapse (hazard ratio 1.32, p-value=0.04) after haplo-identical transplantation, with similar non-relapse mortality risks. Chronic graft-versus-host disease was higher after matched unrelated donor compared to haplo-identical transplantation when bone marrow was the graft (hazard ratio 3.12, p-value<0.001), but when the graft was peripheral blood the risk of chronic graft-versus-host disease did not differ by donor type. These data support matched unrelated donor transplant with donors younger than 40 years is preferred.

Abstract

Classical Hodgkin lymphoma (cHL) patients with relapsed or refractory disease may benefit from allogeneic hematopoietic cell transplantation (allo-HCT), but many lack a matched sibling donor (MSD). Herein, we compare outcomes of two reduced-intensity conditioning (RIC) HCT platforms in cHL: T cell-replete related donor haploidentical (haplo) HCT with post-transplantation cyclophosphamide (PTCy)-based approach versus MSD/calcineurin inhibitor (CNI)-based approach. The study included 596 adult patients who underwent a first RIC allo-HCT for cHL between 2008-2016, using either haplo-PTCy (n=139) or MSD/CNI-based (n=457) approach. Overall survival (OS) was the primary endpoint. Secondary endpoints included acute (a) and (c) graft-versus-host disease (GVHD), non-relapse mortality (NRM), relapse/progression, and progression-free survival (PFS). On multivariate analysis, there was no significant difference between haplo/PTCy and MDS/CNI-based approaches in terms of OS (hazard ratio [HR]=1.07; 95%CI=0.79-1.45; p=0.66) or PFS (HR=0.86; 95%CI=0.68-1.10; p=0.22). Haplo/PTCy was associated with a significantly higher risk of grade 2-4 aGVHD (odds ratio [OR]=1.73, 95%CI=1.16-2.59, p=0.007), but the risk of grade 3-4 aGVHD was not significantly different between the two cohorts (OR=0.61, 95%CI=0.29-1.27, p=0.19). The haplo/PTCy platform provided a significant reduction in cGVHD risk (HR=0.45, 95%CI=0.32-0.64, p<0.001), and a significant reduction in relapse risk (HR=0.74, 95%CI=0.56-0.97, p=0.03). There was a statistically non-significant trend towards higher NRM with haplo/PTCy approach (HR=1.65, 95%CI=0.99-2.77, p=0.06). Haplo/PTCy-based approaches are associated with lower incidence of cGVHD and relapse, with PFS and OS outcomes comparable to MSD/CNI-based approaches. There was a leaning towards higher NRM with haplo/PTCy-based platform. These data show that haplo/PTCy allo-HCT in cHL results in survival comparable to MSD/CNI-based allo-HCT.

Abstract

The Predicted Indirectly Recognizable HLA Epitopes (PIRCHE) score quantifies the number of PIRCHE between patient and donor pairs and represents an in silico measure of indirect alloreactivity. This biologic process is defined as T cell recognition of epitopes derived from mismatched, allogeneic HLA peptides that are subsequently presented by shared HLA molecules. Its association with clinical outcome has not been examined in haplo-HCT with PTCy. We hypothesized that PIRCHE scores would correlate with indirect alloreactivity and predict graft-versus-host disease (GvHD) risk and incidence of relapse after haplo-HCT with PTCy. To address this, we retrospectively analyzed 148 patients who received peripheral blood, T cell-replete haplo-HCT with PTCy at a single center between 2009 and 2016. PIRCHE scores (PS) were calculated using the PIRCHE online matching tool. PS were categorized by class and vector. The median class I graft-versus-host (GvH) PS was 11 (range, 0-56), while the median class I host-versus-graft (HvG) PS was 10 (range 0-51). The class I GvH PS was associated with increased grade II-IV aGvHD (adjusted HR or aHR 1.03 per PS unit increase; 95% CI 1.01-1.05; p=0.008) but not chronic GvHD or incidence of relapse. PIRCHE scores represent a novel strategy to predict clinical outcome in haplo-HCT. Further studies using registry data and prospective cohorts are warranted to validate these findings.