"No donor"? Consider a haploidentical transplant

Myeloablative Haploidentical Donor Hematopoietic Transplantation Using Post-Transplantation Cyclophosphamide and Antithymocyte Globulin

Haploidentical donor (haplo-) hematopoietic stem cell transplantation (HSCT) with post-transplantation cyclophosphamide (PTCy) is now performed on a large scale worldwide. Our patient outcomes did not completely reflect the results published by other groups. We herein present the results of 60 patients with hematologic malignancies treated homogeneously on a modified version of the standard protocol by adding ATG as an additional graft-versus-host disease (GVHD) prophylaxis measure. This was a retrospective analysis of 60 haplo-HSCT recipients using a myeloablative conditioning regimen with antithymocyte globulin and PTCy for GVHD prophylaxis. At 5 years, overall survival was 59.2%, relapse-free survival (RFS) was 48.6%, and chronic GVHD (cGVHD) and relapse-free survival was 40%. The median time to neutrophil and platelet engraftment was 16 days and 28.5 days, respectively. The rates of grade II-IV acute GVHD and extensive cGVHD were 46.7% and 23.3%, respectively. The cumulative incidence of relapse was 30%, nonrelapse mortality was 21.6%, and transplantation-related mortality was 11%. Higher Disease Risk Index and 50% HLA match were associated with lower RFS. Female donor to male recipient and older donor age were associated with an elevated risk of cGVHD. The use of PTCy might not yield the same results in different populations. Many remaining questions need to be addressed in randomized trials, including optimal graft source and donor, date of calcineurin inhibitor initiation, personalized or targeted dose of PTCy, immune reconstitution, and others.

PTCY-Based Haploidentical Donor Transplantation versus HLA-Matched Related and Unrelated Donor Transplantations in Patients with Refractory or Relapsed Lymphoma-A Matched-Pair Analysis

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has demonstrated its potential as a curative option for patients with r/r lymphoma. With the introduction of post-transplant cyclophosphamide-based (PTCY) graft-versus-host disease (GvHD) prophylaxis, allo-HCT using haploidentical related donors (Haplo-HSCT) has emerged as a valuable alternative for patients without an available HLA-matched donor. In this study, we compared intermediate and long-term outcomes between Haplo-HSCT and HLA-matched related donor (MRD) and unrelated donor (URD) transplantations in 16 matched pairs using age, disease status, lymphoma classification and performance status as matching criteria. Of note, 88% of patients in each group presented with active disease at the time of conditioning. After a median follow-up of >10 years, 10-year overall and progression-free survival and non-relapse mortality incidence after Haplo-HSCT were 31%, 25% and 38%, respectively, and did not differ compared to the values observed in MRD-HSCT and URD-HSCT. A remarkable lower incidence of acute GvHD ≥ II and moderate and severe chronic GvHD was observed after Haplo-HSCT compared to MRD-HSCT (50%/50%, p = 0.03/0.03) and URD-HSCT (44%/38%, p = 0.04/0.08), resulting in slightly higher 10-year GvHD-free and relapse-free survival (25%) and chronic GvHD-free and relapse-free survival (25%) in the Haplo-HSCT group. In conclusion, Haplo-HSCT is an effective treatment in patients with non-remission NHL. Given its advantage of immediate availability, haploidentical donors should be preferably used in patients with progressive disease lacking an HLA-matched related donor.

"Incidence and significance of donor-specific antibodies in haploidentical stem cell transplantation"

PGF is a devastating complication after allogeneic transplant. We retrospectively analyzed our haploidentical transplant registry to report the incidence and impact of DSA and anti-HLA on engraftment. 107 patients were identified. Median recipient-age of 22, median donor-age of 31. Sixty-two patients had AML (58%), 29 had ALL (27%), 16 (15%) had other malignancies. Sixty-one recipients (57%) had positive anti-HLA, 56 of them had the DSA results available, of these 17 patients had DSAs (15% of the total number of patients, or 28% of patients who have anti-HLA antibodies). The median cumulative MFI was 2062. Sixty-three percent of the DSA were against class-II HLA antigens. The OS, CIR, aGvHD, and cGvHD did not differ between patients with and without anti-HLA antibodies, nor between patients with and without DSA. The gender of the recipient and donor, as well as the gender mismatch between recipient and donor, were statistically associated with the incidence of anti-HLA antibodies. Three patients only developed GF (2.8%), one was primary (0.9%) and the other two secondary GF (1.9%). None of the GF cases was in patients with anti-HLA antibodies or DSA. The presence of anti-HLA or DSAs did not affect the outcomes including the incidence of PGF.

Lower dose of ATG combined with basiliximab for haploidentical hematopoietic stem cell transplantation is associated with effective control of GVHD and less CMV viremia

Currently, the graft-versus-host disease (GVHD) prophylaxis consists of an immunosuppressive therapy mainly based on antithymocyte globulin (ATG) or post-transplant cyclophosphamide (PTCy). GVHD remains a major complication and limitation to successful allogeneic haploidentical hematopoietic stem cell transplantation (haplo-HSCT). We modified the ATG-based GVHD prophylaxis with the addition of basiliximab in the setting of haplo-HSCT and attempted to explore the appropriate dosages. We conducted a retrospective analysis of 239 patients with intermediate- or high-risk hematologic malignancies who received haplo-HSCT with unmanipulated peripheral blood stem cells combined or not with bone marrow. All patients received the same GVHD prophylaxis consisting of the combination of methotrexate, cyclosporine or tacrolimus, mycofenolate-mofetil, and basiliximab with different doses of ATG (5-9mg/kg). With a median time of 11 days (range, 7-40 days), the rate of neutrophil engraftment was 96.65%. The 100-day cumulative incidences (CIs) of grade II-IV and III-IV aGVHD were 15.8 ± 2.5% and 5.0 ± 1.5%, while the 2-year CIs of total cGVHD and extensive cGVHD were 9.8 ± 2.2% and 4.1 ± 1.5%, respectively. The 3-year CIs of treatment-related mortality (TRM), relapse, overall survival (OS), and disease-free survival (DFS) were 14.6 ± 2.6%, 28.1 ± 3.4%, 60.9 ± 3.4%, 57.3 ± 3.4%, respectively. Furthermore, the impact of the reduction of the ATG dose to 6 mg/kg or less in combination with basiliximab on GVHD prevention and transplant outcomes among patients was analyzed. Compared to higher dose of ATG(>6mg/kg), lower dose of ATG (≤6mg/kg) was associated with a significant reduced risk of CMV viremia (52.38% vs 79.35%, P<0.001), while the incidences of aGVHD and cGVHD were similar between the two dose levels. No significant effect was found with regard to the risk of relapse, TRM, and OS. ATG combined with basiliximab could prevent GVHD efficiently and safely. The optimal scheme of using this combined regimen of ATG and basiliximab is that administration of lower dose ATG (≤6mg/kg), which seems to be more appropriate for balancing infection control and GVHD prophylaxis.

Donor selection for KIR alloreactivity is associated with superior survival in haploidentical transplant with PTCy

With the continuous increase in the use of haploidentical donors for transplantation, the selection of donors becomes increasingly important. Haploidentical donors have been selected primarily based on clinical characteristics, while the effects of killer cell immunoglobulin-like receptors (KIRs) on outcomes of haploidentical-hematopoietic stem cell transplantation (haplo-HSCT) with post-transplant cyclophosphamide (PTCy) remain inconclusive. The present study aimed to thoroughly evaluate the effect of KIRs and binding ligands assessed by various models, in addition to other patient/donor variables, on clinical outcomes in haplo-HSCT. In a cohort of 354 patients undergoing their first haplo-HSCT, we found that a higher Count Functional inhibitory KIR score (CF-iKIR) was associated with improved progression-free survival (adjusted hazard ratio [HR], 0.71; P = .029) and overall survival (OS) (HR, 0.66; P = .016), while none of the other models predicted for survival in these patients. Moreover, using exploratory classification and regression tree analysis, we found that donor age &lt;58 years combined with cytomegalovirus-nonreactive recipient was associated with the best OS, whereas donor age &gt;58 years was associated with the worst OS. In the rest of our cohort (80%), cytomegalovirus-reactive recipients with a donor &lt;58 years old, a higher CF-iKIR was associated with superior OS. The 3-year OS rates were 73.9%, 54.1% (HR, 1.84; P = .044), 44.5% (HR, 2.01; P = .003), and 18.5% (HR, 5.44; P &lt;.001) in the best, better, poor, and worse donor groups, respectively. Our results suggest that KIR alloreactivity assessed by CF-iKIR score can help optimize donor selection in haplo-HSCT.

Number of HLA-Mismatched Eplets Is Not Associated with Major Outcomes in Haploidentical Transplantation with Post-Transplantation Cyclophosphamide: A Center for International Blood and Marrow Transplant Research Study

The number of haploidentical hematopoietic stem cell transplantations (haplo-HSCT) performed has increased substantially in recent years. Previous single-center studies using in silico algorithms to quantitively measure HLA disparity have shown an association of the number of HLA molecular mismatches with relapse protection and/or increased risk of acute graft-versus-host disease (GVHD) in haplo-HSCT. However, inconsistent results from small studies have made it difficult to understand the full clinical impact of molecular mismatch in haplo-HSCT. In this study, we investigated the potential of the HLA class I and II mismatched eplet (ME) score measured by HLAMatchmaker, as well as ME load at a specific locus to predict outcomes in a registry-based cohort of haplo-HSCT recipients. We analyzed data from 1287 patients who underwent their first haplo-HSCT for acute lymphoblastic leukemia, acute myelogenous leukemia, or myelodysplastic syndrome between 2013 and 2017, as entered in the Center for International Blood and Marrow Transplant Research database. ME load at each HLA locus and total class I and II were scored using the HLAMatchmaker module incorporated in HLA Fusion software v4.3, which identifies predicted eplets based on the crystalized HLA molecule models and identifies ME by comparing donor and recipient eplets. In the study cohort, ME scores derived from total HLA class I or class II loci or individual HLA loci were not associated with overall survival, disease-free survival, nonrelapse mortality, relapse, acute GVHD, or chronic GVHD (P < .01). An unexpected strong association was identified between total class II ME load in the GVH direction and slower neutrophil engraftment (hazard ratio [HR], 0.82; 95% confidence interval [CI], 0.75 to 0.91; P < .0001) and platelet engraftment (HR, 0.80; 95% CI, 0.72 to 0.88; P < .0001). This was likely attributable to ME load at the HLA-DRB1 locus, which was similarly associated with slower neutrophil engraftment (HR, 0.82; 95% CI, 0.73 to 0.92; P = .001) and slower platelet engraftment (HR, 0.76; 95% CI, 0.70 to 0.84; P < .0001). Additional analyses suggested that this effect is attributable to a match versus a mismatch in the graft-versus-host direction and not to ME load, as a dose effect was not identified. These findings contradict those of previous relatively small studies reporting an association between ME load, as quantified by HLAMatchmaker, and haplo-HSCT outcomes. This study failed to demonstrate the predictive value of ME from HLA molecules for major clinical outcomes, and other molecular mismatch algorithms in haplo-HSCT settings should be tested.

Treatment of allosensitized patients receiving allogeneic transplantation

Treatment with PE, rituximab, IVIg, and donor buffy coat is effective in promoting engraftment in patients with DSA <20 000 MFI.

Patients with persistent positive C1q at transplant have a higher risk of engraftment failure and poor survival.

Donor-specific anti-HLA antibodies (DSAs) are a major cause of engraftment failure in patients receiving haploidentical stem cell transplantation (HaploSCT). Effective treatments are needed for these patients, who often have no other donor options and/or are in need to proceed urgently to transplantation. We studied a multimodality treatment with alternate-day plasma exchange (PE), rituximab, intravenous γ globulin (IVIg) and an irradiated donor buffy coat for patients with DSAs at 2 institutions. Thirty-seven patients with a median age of 51 years were treated with this desensitization protocol. Treatment outcomes were compared with a control group of HaploSCT patients without DSAs (n = 345). The majority of patients in the DSA group were female (83.8% vs 37.1% in controls, P < .001) and received stem cells from a child as the donor (67.6% vs 44.1%, P = .002). Mean DSA level before and after desensitization was 10 198 and 5937 mean fluorescence intensity (MFI), respectively, with mean differences of 4030 MFI. Fourteen of 30 tested patients (46.7%) had C1q positivity, while 8 of 29 tested patients (27.6%) remained positive after desensitization. In multivariable analysis, patients with initial DSA > 20 000 MFI and persistent positive C1q after desensitization had a significantly lower engraftment rate, which resulted in significantly higher non-relapse mortality and worse overall survival (OS) than controls, whereas graft outcome and survival of patients with initial DSA < 20 000 MFI and those with negative C1q after treatment were comparable with controls. In conclusion, treatment with PE, rituximab, IVIg, and donor buffy coat is effective in promoting engraftment in patients with DSAs ≤20 000 MFI.

Molecular disparity in human leukocyte antigens is associated with outcomes in haploidentical stem cell transplantation

Haploidentical donors are increasingly used for patients requiring hematopoietic stem cell transplantation (HSCT). Although several factors have been associated with transplant outcomes, the impact of HLA disparity in haploidentical HSCT (haplo-HSCT) remains unclear. We investigated the impact of HLA disparity quantified by mismatched eplets (ME) load of each HLA locus on the clinical outcome of 278 consecutive haploidentical transplants. Here, we demonstrated that the degree of HLA molecular mismatches, at individual HLA loci, may be relevant to clinical outcome in the haplo-HSCT. A significantly better overall survival was associated with higher ME load from HLA-A (hazard ratio [HR], 0.97; 95% confidence interval [CI], 0.95-0.99; P = .003) and class I loci (HR, 0.99; 95% CI, 0.97-0.99; P = .045) in the host-versus-graft direction. The apparent survival advantage of HLA-A ME was primarily attributed to reduced risk in relapse associated with an increase in HLA-A ME load (subdistribution HR, 0.95; 95% CI, 0.92-0.98; P = .004). Furthermore, we have identified an association between the risk of grade 3-4 acute graft-versus-host disease (GVHD) and a higher ME load at HLA-B and class I loci in graft-versus-host (GVH) direction. Additionally, GVH nonpermissive HLA-DPB1 mismatch defined by T-cell epitope grouping was significantly associated with relapse protection (subdistribution HR, 0.19; 95% CI, 0.06-0.59; P = .004) without a concurrent increase in GVHD. These findings indicate that alloreactivity generated by HLA disparity at certain HLA loci is associated with transplant outcomes, and ME analysis of individual HLA loci might assist donor selection and risk stratification in haplo-HSCT.

Haploidentical stem cell transplantation vs matched unrelated donor transplantation in adults with hematologic malignancies: a systematic review and meta-analysis

OBJECTIVES

Haploidentical hematopoietic stem cell transplantation (Haplo-SCT) and matched unrelated donor transplantation (MUD-SCT) are two important options when a matched sibling donor (MSD) is unavailable. Several studies comparing Haplo-SCT and MUD-SCT have reported inconsistent clinical outcomes. Therefore, it is necessary to synthesize the existing evidence regarding outcomes of stem cell transplantations comparing Haplo-SCT with MUD-SCT.

METHODS

We searched for titles of articles in MEDLINE (PubMed), Cochrane library, EMBASE database that compared transplantation with Haplo-SCT versus MUD-SCT. To compare clinical outcomes between Haplo-SCT and MUD-SCT, we performed a meta-analysis of 17 studies and reported the pooled odd ratios (OR) of 6 endpoints including overall survival (OS), progression free survival (PFS), non-relapse mortality (NRM), relapse rate (RR), acute graft-versus-host disease (aGVHD) and chronic graft- versus-host disease (cGVHD).

RESULTS

We found that Haplo-SCT was associated with a comparable OS (pooled OR of 0.99, 95% Confidence Interval (CI) 0.86-1.14), PFS (OR 1.00, 95% CI 0.88-1.15), NRM (OR 0.83, 95% CI 0.65-1.04) and RR (OR 1.08, 95% CI 0.95-1.22) compared to MUD-SCT. We also found a significantly decreased risk of aGVHD (OR 0.74, 95% CI 0.62-0.88) and cGVHD (OR 0.50, 95% CI 0.38-0.66) in Haplo-SCT group.

CONCLUSION

Results of this meta-analysis demonstrates that Haplo-SCT achieves comparable clinical outcomes compared to MUD-SCT in terms of OS, PFS, TRM and RR, but is better than MUD-SCT in terms of decreased aGVHD and cGVHD risk. Haplo-SCT is a valid option for patient needing urgent transplantation.

Haploidentical transplants for patients with relapse after the first allograft

Relapse after allogeneic hematopoietic stem-cell transplantation (AHSCT) is associated with very poor outcomes. A second transplant offers the possibility of long-term disease control. We analyzed outcomes with haploidentical donors for second allograft at our institution. All consecutive patients with hematological malignancies (N = 29) who relapsed after AHSCT and underwent a haploidentical transplant (haploSCT) as second transplant between February 2009 and October 2018 were included. Median age was 36 years (interquartile range (IQR) 24-60); 83% of patients had high/very high disease risk index; 61% of AML/MDS patients had high-risk cytogenetics; and only 24% were in complete remission at transplant. With a median follow-up of 46.9 months, the 3-year relapse, non-relapse mortality (NRM), progression-free survival (PFS) and overall survival (OS) were 30%, 39%, 31% and 40%, respectively. In multivariable analysis (MVA), comorbidity index (HCT-CI) and detectable donor-specific anti-HLA antibodies (DSA) prior to second transplant were significantly associated with worse outcomes. Patients with HCT-CI <3 and without DSA had 3-year PFS and OS of 53% and 60.3%, respectively. Our findings suggest that haploSCT as second AHSCT is feasible and potentially curative. Lower HCT-CI and no DSA were associated with lower NRM and improved survival. Haploidentical grafts might be a preferred donor source for second AHSCT as these are high-risk patients who frequently need to proceed urgently to transplant.

Similar transplant outcomes between haploidentical and unrelated donors after reduced-intensity conditioning with busulfan, fludarabine, and anti-thymocyte globulin in patients with acute leukemia or myelodysplastic syndrome

Background

Although T-cell-replete hematopoietic cell transplantation (HCT) from haploidentical donors (HIDs) using anti-thymocyte globulin (ATG) has shown promising outcomes, previous studies often adopted heterogenous graft sources and conditioning.

Methods

We retrospectively compared HCT outcomes from 62 HIDs, 36 partially-matched unrelated donors (PUDs), and 55 matched unrelated donors (MUDs) in patients with acute leukemia or myelodysplastic syndrome using the same graft source of peripheral blood and a reduced intensity conditioning of busulfan, fludarabine, and ATG.

Results

The estimates of 3-yr disease-free survival (DFS) and overall survival (OS) rates were not significantly different among the MUD, HID, and PUD groups, at 46%, “41%, and 36%” for the DFS rate (P=0.844), and 55%, 45%, and 45% for the OS rate (P=0.802), respectively. Cumulative incidence of relapse and non-relapse mortality at 3 yr was similar among different donor types. Subsequent multivariable analyses showed that the sex of the patient (male) and a high/very high disease risk index were independently associated with poorer DFS and OS, while the donor type was not.

Conclusion

T-cell replete HCT from HIDs using an ATG-containing reduced intensity conditioning regimen may be a reasonable option in the absence of matched related donors in patients with acute leukemia or myelodysplastic syndrome.

Let's Talk About BiTEs and Other Drugs in the Real-Life Setting for B-Cell Acute Lymphoblastic Leukemia

Background: Therapy for acute lymphoblastic leukemia (ALL) are currently initially efficient, but even if a high percentage of patients have an initial complete remission (CR), most of them relapse. Recent data shows that immunotherapy with either bispecific T-cell engagers (BiTEs) of chimeric antigen receptor (CAR) T cells can eliminate residual chemotherapy-resistant B-ALL cells.

Objective: The objective of the manuscript is to present improvements in the clinical outcome for chemotherapy-resistant ALL in the real-life setting, by describing Romania's experience with bispecific antibodies for B-cell ALL.

Methods: We present the role of novel therapies for relapsed B-cell ALL, including the drugs under investigation in phase I-III clinical trials, as a potential bridge to transplant. Blinatumomab is presented in a critical review, presenting both the advantages of this drug, as well as its limitations.

Results: Bispecific antibodies are discussed, describing the clinical trials that resulted in its approval by the FDA and EMA. The real-life setting for relapsed B-cell ALL is described and we present the patients treated with blinatumomab in Romania.

Conclusion: In the current manuscript, we present blinatumomab as a therapeutic alternative in the bridge-to-transplant setting for refractory or relapsed ALL, to gain a better understanding of the available therapies and evidence-based data for these patients in 2019.

Low incidence of hemorrhagic cystitis following ex vivo T-cell depleted haploidentical hematopoietic cell transplantation in children

Hemorrhagic cystitis (HC) is a debilitating complication following allogenic hematopoietic cell transplantation (HCT). HLA disparity and T-cell depletion have been implicated as risk factors for HC. However, reports on the incidence and risk factors for HC in ex vivo T-cell depleted haploidentical HCT (haploHCT) in children are lacking. We studied 96 haploHCT procedures performed in 83 children between 2002 and 2017. Sixty-three patients were diagnosed with a malignant disease and 20 with nonmalignant disease. All but three patients with SCID underwent myelotoxic and/or lymphotoxic conditioning therapy. Grafts were CD3+ (36.5%) or TcRαβ+ (63.5%) depleted to prevent graft versus host disease (GvHD). Fourteen patients (14.6%) were diagnosed with HC; 12 (12.5%) had clinically significant stage II-IV HC. All patients with HC had BK viruria and/or viremia. Increasing age and chemotherapeutic treatment prior to conditioning were identified as risk factors for HC. Immune recovery did not significantly differ between patients with and without HC. Thus, we report a low incidence of HC in pediatric haploHCT using ex vivo T-cell depletion. The combination of a reduced toxicity conditioning regimen, and typically absent pharmaceutical post-HCT GvHD prophylaxis in our patients might have contributed to the decreased the risk of HC, despite HLA disparity.

New Strategy of Acute Graft-vs-Host Disease: Investigation of a Reduced Dose of Antithymocyte Globulin in Haploidentical Hematopoietic Stem Cell Transplantation

Graft-vs-host disease (GVHD) is one of the biggest challenges in haploidentical hematopoietic stem cell transplantation. Antithymocyte globulins (ATGs) are widely used to overcome GVHD, but excessive immunosuppression increases the chances of relapse and infection following transplantation. No defined standard of the appropriate dose of ATG usage is recognized. The study included 11 patients who were treated with a reduced dose of ATG to prevent GVHD in haploidentical hematopoietic stem cell transplantation. A reduced dose of ATG-Thymoglobulin (total dose of 5 mg/kg) was used in the pretreatment protocol for 2 consecutive days. All patients had successful transplantation. The median time of neutrophil engraftment was 12 days. All chimerism tests passed on day 30, 60, and 90 post transplantation. None of the patients had acute GVHD, while only 2 patients had I to II degree chronic GVHD (18.2%). No transplantation-related deaths were observed. The current findings suggest that the reduced dose of ATG can effectively prevent the incidence of acute GVHD in haploidentical hematopoietic stem cell transplantation.

High-resolution HLA phased haplotype frequencies to predict the success of unrelated donor searches and clinical outcome following hematopoietic stem cell transplantation

HLA matching is a critical factor for successful allogeneic hematopoietic stem cell transplantation. For unrelated donor searches, matching is usually based on high-resolution typing at five HLA loci, looking for a 10/10 match. Some studies have proposed that further matching at the haplotype level could be beneficial for clinical outcome. In this study, we determined the phased haplotypes of 291 patients using family members and segregation analysis. The sum of ranks of the haplotypes carried by patients was used as a surrogate predictor of a successful unrelated donor search. The putative impact of haplotypes was then analyzed in a cohort of 211 recipients transplanted with 10/10 matched unrelated donors. A logistic regression analysis showed a highly significant effect of the haplotypes in the outcome of a search, but we did not find any significant effect on overall survival, graft versus host disease or relapse/progression following HSCT. This study provides useful data for the optimization of unrelated bone marrow donor searches, but does not confirm previous reports that matching at the haplotype level has a clinical impact following HSCT. Due to the extreme polymorphism of HLA genes, further studies are warranted to better understand the many factors at play.

Review of Haploidentical Hematopoietic Cell Transplantation

Use of haploidentical (haplo) donors for hematopoietic cell transplantation (HCT) has significantly increased in the last decade. The major advantage with this strategy is universal availability and faster acquisition of the donor, along with affordability and provision of immunotherapy in post-transplantation period. Historically, haplo-HCT was associated with compromised outcomes because of high rates of graft-versus-host disease and graft failure, but after the development of a post-transplantation high-dose cyclophosphamide strategy, which results in selective T-cell depletion, these issues have been addressed to a large extent. Nevertheless, graft failure, high treatment-related mortality due to graft-versus-host disease, infections, delayed immune reconstitution, and disease relapse remain significant concerns. As the experience with haplo-HCTs grows, the clinical outcomes are becoming more at par with those seen with fully matched unrelated donor allogeneic HCTs.

Evidence for persistence of the SHIV reservoir early after MHC haploidentical hematopoietic stem cell transplantation

Allogeneic transplantation (allo-HCT) has led to the cure of HIV in one individual, raising the question of whether transplantation can eradicate the HIV reservoir. To test this, we here present a model of allo-HCT in SHIV-infected, cART-suppressed nonhuman primates. We infect rhesus macaques with SHIV-1157ipd3N4, suppress them with cART, then transplant them using MHC-haploidentical allogeneic donors during continuous cART. Transplant results in ~100% myeloid donor chimerism, and up to 100% T-cell chimerism. Between 9 and 47 days post-transplant, terminal analysis shows that while cell-associated SHIV DNA levels are reduced in the blood and in lymphoid organs post-transplant, the SHIV reservoir persists in multiple organs, including the brain. Sorting of donor-vs.-recipient cells reveals that this reservoir resides in recipient cells. Moreover, tetramer analysis indicates a lack of virus-specific donor immunity post-transplant during continuous cART. These results suggest that early post-transplant, allo-HCT is insufficient for recipient reservoir eradication despite high-level donor chimerism and GVHD.

Allogeneic hematopoietic cell transplantation (allo-HCT) has led to the cure of HIV in one individual, but the underlying mechanisms are unclear. Here, the authors present a model of allo-HCT in SHIV-infected nonhuman primates and show that the SHIV reservoir persists in multiple tissues early after transplantation.

T-cell replete haploidentical stem cell transplantation attenuates the prognostic impact of FLT3-ITD in acute myeloid leukemia: A report from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

Acute myeloid leukemia (AML) patients harboring the FLT3-ITD mutation are considered a high risk patient subset preferentially allocated for allogeneic stem cell transplantation in first remission. Whether FLT3-ITD retains a prognostic role in haploidentical stem cell transplantation (haplo-SCT) is unknown. To analyze the prognostic impact of FLT3-ITD in haplo-SCT, we performed a retrospective analysis of the multicenter registry of the acute leukemia working party of the European Society for Blood and Marrow Transplantation. We included all adult AML patients with known FLT3 status who underwent a first T-cell replete related haplo-HCT in first complete remission from 2005 to 2016. We evaluated 293 patients of whom 202 were FLT3^wt and 91 were FLT3-ITD mutated. FLT3-ITD patients were more likely to be NPM1 mutated as well as be in the intermediate risk cytogenetic risk category. In multivariate analysis, patients with FLT3-ITD had comparable rates of relapse incidence [Hazard ratio (HR) = 1.34, confidence interval (CI) 95%, 0.67-2.7; P = .9] and leukemia-free survival (HR = 0.99, CI 95%, 0.62-1.57; P = .9) to those of FLT3^wt patients. Overall survival, the incidence of nonrelapse mortality, and graft versus host disease-free/relapse-free survival were not significantly impacted by FLT3-ITD status. Furthermore, relapse and overall survival were comparable between FLT3-ITD patients transplanted from various donor pools, namely matched siblings, unrelated donors, haplo-SCT). Finally, subset analysis of patients with intermediate risk cytogenetics confirmed the absence of a prognostic impact of FLT3-ITD also for this patient segment. In AML patients undergoing T-cell replete haplo-SCT, the FLT3-ITD mutation possibly does not retain its prognostic significance.

Idarubicin-intensified haploidentical HSCT with GvHD prophylaxis of ATG and basiliximab provides comparable results to sibling donors in high-risk acute leukemia

We designed a novel haploidentical hematopoietic stem cell transplantation (haplo-HSCT) system using idarubicin (IDA) intensified conditioning regimens and combination of antithymocyte globulin and basiliximab for GvHD prophylaxis. The outcomes of 110 high-risk acute leukemia patients undergoing haplo-HSCT were compared with 69 contemporaneous high-risk patients receiving HLA-matched sibling transplantation using uniform IDA-intensified regimens. The relapse incidence of haplo-HSCT was 23.4%, and 3-year overall survival (OS) and disease-free survival (DFS) achieved 62.9%, 59.1%, respectively. The cumulative incidences of II-IV and III-IV aGvHD were 28.6 and 14.3%, while limited and extensive cGvHD were 19.4, 13.8%. All these results were equivalent to those of concurrent identical sibling transplantation. Three-year OS and DFS for patients in advance stage reached 48.5, 47.3%. Furthermore, the relapse, 3-year OS of positive minimal residual disease (MRD) patients did not differ from negative MRD patients (18.9% vs 11.5%, 63.6% vs 69.6%), indicating our intensified haplo-HSCT technique could circumvent the dismal prognosis of MRD. These data provide reinforcing evidence that our haplo-HSCT system could dramatically improve the survival of high-risk acute leukemia with low relapse and acceptable transplantation-related mortality, and might be a promising therapeutic option for high-risk patients.

Unmanipulated haploidentical stem cell transplantation in adults with acute lymphoblastic leukemia: a study on behalf of the Acute Leukemia Working Party of the EBMT

Background

Allogenic hematopoietic stem cell transplantation (allo-SCT) is the most effective post-remission treatment for adults with high-risk acute lymphoblastic leukemia (ALL). The aim of the study was to analyze results of unmanipulated haploidentical allo-SCT (haplo-SCT) for adults with ALL and to identify prognostic factors.

Methods

We performed a retrospective analysis on 208 adults transplanted in EBMT centers from 2007 to 2014.

Results

Median age at haplo-SCT was 32 years and median follow-up, 31 months. Forty-four percent of the patients were in first complete remission (CR1). Stem cell source was the bone marrow (BM) for 43% and peripheral blood (PB) for 57% of patients. Myeloablative conditioning (MAC) was used for 66% and reduced intensity regimen (RIC) for 34% of patients. GVHD prophylaxis was based on post-transplant cyclophosphamide (PT-Cy) for 118 (57%) or on anti-thymocyte-globulin (ATG) for 90 (43%) plus standard prophylaxis. One hundred eighty-four (92%) patients achieved engraftment. Cumulative incidence (CI) of grade II–IV acute-graft-versus-host-disease (GVHD) was 31%, grade III–IV 11%, and chronic GVHD 29%. Non-relapse mortality (NRM) and relapse-incidence (RI) were 32 and 37%, respectively. Overall survival (OS), leukemia-free survival (LFS), and GVHD-free, relapse-free-survival (GRFS) at 3 years were 33, 31, and 26%. For patients in CR1, OS, LFS, and GRFS were 52, 47, and 40%, respectively. Disease status was the main factor associated with transplant outcomes. Use of BM was independently associated with improvement in NRM, acute GVHD, GRFS, LFS, and OS.

Conclusions

Unmanipulated haplo-SCT may be considered a valid option for adult patients with high-risk ALL lacking HLA identical donor preferably in early disease status.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-017-0480-5) contains supplementary material, which is available to authorized users.

Outcomes of haploidentical transplant compared with matched donor allogeneic stem cell transplant

The risk of acute and chronic graft-versus-host disease (GVHD) with haploidentical transplant with post-transplant high-dose cyclophosphamide may be lower compared with matched unrelated donor transplant and largely similar to matched related donor transplant. The lower probability of GVHD with the haploidentical donor may result in a risk of nonrelapse mortality that is at least similar to or even lower than the matched donor. The incidence of relapse and survival are also largely similar to different donor types. Haploidentical transplant may be associated with slower engraftment. Given a lower risk of GVHD, haploidentical transplant has gained popularity. Additionally, the use of post-transplant high-dose cyclophosphamide has been extended to lower the risk of GVHD with matched donor and mismatched unrelated donor transplant.

Preservation of Antigen-Specific Functions of αβ T Cells and B Cells Removed from Hematopoietic Stem Cell Transplants Suggests Their Use As an Alternative Cell Source for Advanced Manipulation and Adoptive Immunotherapy

Hematopoietic stem cell transplantation is standard therapy for numerous hematological diseases. The use of haploidentical donors, sharing half of the HLA alleles with the recipient, has facilitated the use of this procedure as patients can rely on availability of a haploidentical donor within their family. Since HLA disparity increases the risk of graft-versus-host disease, T-cell depletion has been used to remove alloreactive lymphocytes from the graft. Selective removal of αβ T cells, which encompass the alloreactive repertoire, combined with removal of B cells to prevent EBV-related lymphoproliferative disease, proved safe and effective in clinical studies. Depleted αβ T cells and B cells are generally discarded as by-products. Considering the possible use of donor T cells for donor lymphocyte infusions or for generation of pathogen-specific T cells as mediators of graft-versus-infection effect, we tested whether cells in the discarded fractions were functionally intact. Response to alloantigens and to viral antigens comparable to that of unmanipulated cells indicated a functional integrity of αβ T cells, in spite of the manipulation used for their depletion. Furthermore, B cells proved to be efficient antigen-presenting cells, indicating that antigen uptake, processing, and presentation were fully preserved. Therefore, we propose that separated αβ T lymphocytes could be employed for obtaining pathogen-specific T cells, applying available methods for positive selection, which eventually leads to indirect allodepletion. In addition, these functional T cells could undergo additional manipulation, such as direct allodepletion or genetic modification.

Haploidentical Stem Cell Transplantation in Adult Haematological Malignancies

Haematopoietic stem cell transplantation is a well-established treatment option for both hematological malignancies and nonmalignant conditions such as aplastic anemia and haemoglobinopathies. For those patients lacking a suitable matched sibling or matched unrelated donor, haploidentical donors are an alternative expedient donor pool. Historically, haploidentical transplantation led to high rates of graft rejection and GVHD. Strategies to circumvent these issues include T cell depletion and management of complications thereof or T replete transplants with GVHD prophylaxis. This review is an overview of these strategies and contemporaneous outcomes for hematological malignancies in adult haploidentical stem cell transplant recipients.

Optimal graft source for allogeneic hematopoietic stem cell transplant: bone marrow or peripheral blood?

Peripheral blood (PB), compared with bone marrow graft, has higher stem cell content, leads to faster engraftment and is more convenient for collection. Consequently, the use of PB graft has significantly increased in recent years. Although the use of PB graft is acceptable or even preferred to bone marrow graft in matched related donor allogeneic transplant due to a possibility of improved survival, PB graft increases the risk of chronic graft-versus-host disease and associated long-term toxicities in the setting of matched unrelated donor allogeneic transplant. In haploidentical transplant, mitigation of graft-versus-host disease with the use of post-transplant cyclophosphamide is a hypothesis-generating possibility; however, available studies have significant limitations to draw any definite conclusion.

How do we choose the best donor for T-cell-replete, HLA-haploidentical transplantation?

In haploidentical stem cell transplantations (haplo-SCT), nearly all patients have more than one donor. A key issue in the haplo-SCT setting is the search for the best donor, because donor selection can significantly impact the incidences of acute and chronic graft-versus-host disease, transplant-related mortality, and relapse, in addition to overall survival. In this review, we focused on factors associated with transplant outcomes following unmanipulated haplo-SCT with anti-thymocyte globulin (ATG) or after T-cell-replete haplo-SCT with post-transplantation cyclophosphamide (PT/Cy). We summarized the effects of the primary factors, including donor-specific antibodies against human leukocyte antigens (HLA); donor age and gender; killer immunoglobulin-like receptor-ligand mismatches; and non-inherited maternal antigen mismatches. We also offered some expert recommendations and proposed an algorithm for selecting donors for unmanipulated haplo-SCT with ATG and for T-cell-replete haplo-SCT with PT/Cy.

Recent advances in haploidentical hematopoietic stem cell transplantation using ex vivo T cell-depleted graft in children and adolescents

Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative treatment for children and adolescents with various malignant and non-malignant diseases. While human leukocyte antigen (HLA)-identical sibling donor is the preferred choice, matched unrelated volunteer donor is another realistic option for successful HSCT. Unfortunately, it is not always possible to find a HLA-matched donor for patients requiring HSCT, leading to a considerable number of deaths of patients without undergoing transplantation. Alternatively, allogeneic HSCT from haploidentical family members could provide donors for virtually all patients who need HSCT. Although the early attempts at allogeneic HSCT from haploidentical family donor (HFD) were disappointing, recent advances in the effective ex vivo depletion of T cells or unmanipulated in vivo regulation of T cells, better supportive care, and optimal conditioning regimens have significantly improved the outcomes of haploidentical HSCT. The ex vivo techniques used to remove T cells have evolved from the selection of CD34⁺ hematopoietic stem cell progenitors to the depletion of CD3⁺ cells, and more recently to the depletion of αβ⁺ T cells. The recent emerging evidence for ex vivo T cell-depleted haploidentical HSCT has provided additional therapeutic options for pediatric patients with diseases curable by HSCT but has not found a suitable related or unrelated donor. This review discusses recent advances in haploidentical HSCT, focusing on transplant using ex vivo T cell-depleted grafts. In addition, our experiences with this novel approach for the treatment of pediatric patients with malignant and non-malignant diseases are described.

Specific removal of alloreactive T-cells to prevent GvHD in hemopoietic stem cell transplantation: rationale, strategies and perspectives

Hemopoietic stem cell transplantation (HSCT) is a standard procedure for treatment of malignant and non-malignant hematological diseases. HSCT donors include HLA-identical siblings, matched or mismatched unrelated donors and haploidentical related donors. Graft-versus-host disease (GvHD), mediated by donor alloreactive T-cells in the graft, can be triggered by minor histocompatibility antigens in HLA-identical pairs, by alleles at loci not considered for MUD-matching or by the mismatched haplotype in haplo-HSCT. Therefore, removal of donor T-cells, that contain the alloreactive precursors, is required, but T-cell depletion associates with opportunistic infections and with reduced graft-versus-leukemia effect. Selective T-cell depletion strategies have been introduced, like removal of αβ T-lymphocytes and of naive T-cells, two subsets including the alloreactive precursors, but the ultimate goal is specific removal of alloreactive T-cells. Here we review the different approaches to deplete alloreactive T-cells only and discuss pros and cons, specificity, efficiency and efficacy. Combinations of different methods and innovative approaches are also proposed for depleting specific alloreactive T-cells with high efficiency.

Haploidentical Donors: Can Faster Transplantation Be Life-Saving for Patients with Advanced Disease?

Haploidentical stem cell transplantation is a therapeutic option for patients without an HLA-matched donor. It is increasingly being used worldwide due to the application of posttransplantation cyclophosphamide and is associated with lower incidence of graft-versus-host disease and treatment-related mortality. Haploidentical donors are generally available for most patients and stem cells can be rapidly obtained. Delays in transplantation while waiting for unrelated donor cells can be potentially problematic for patients with advanced disease at risk for progression; thus, the use of haploidentical donors, especially in this setting, can be life-saving. Here we reviewed the literature on haploidentical stem cell transplantation performed with posttransplantation cyclophosphamide.

Outcomes of Haploidentical Stem Cell Transplantation for Lymphoma with Melphalan-Based Conditioning

Haploidentical transplantation (Haplo-SCT) with post-transplantation cyclophosphamide (PTCy) is increasingly utilized for the treatment of lymphoma and almost exclusively with the nonmyeloablative fludarabine (Flu)/cyclophosphamide/total body irradiation (TBI) conditioning regimen. We present early results of a reduced-intensity (RIC) regimen utilizing fludarabine and melphalan (FM) for the treatment of advanced lymphoma. All patients with a diagnosis of lymphoma or chronic lymphocytic leukemia (CLL) who received Haplo-SCT at the University of Texas MD Anderson Cancer Center between 2009 and 2014 were reviewed (N = 22). Patients received Flu 160 mg/m(2) and melphalan 100 mg/m(2) to 140 mg/m(2) with thiotepa 5 mg/kg or 2 Gy TBI. Because of concerns of increased treatment-related mortality (TRM) with the melphalan 140 mg/m(2) regimen (FM140), a RIC regimen with melphalan 100 mg/m(2) (FM100) was devised. Rituximab was included for CD20(+) disease. Graft-versus-host disease prophylaxis consisted of PTCy 50 mg/kg on days +3 and + 4, tacrolimus, and mycophenolate mofetil. Sixty-eight percent of all patients were not in complete remission at the time of transplantation. The 2-year progression-free survival (PFS) and overall survival (OS) for the entire cohort were 54%, 1-year TRM was 19%, and the cumulative incidence of relapse at 2 years was 27%. Two-year PFS for Hodgkin lymphoma, non-Hodgkin lymphoma, and CLL/small lymphocytic lymphoma were 57%, 51%, and 75%. Patients treated with FM100 compared to FM140 had equivalent PFS (71% versus 37%, P = .246) and OS (71% versus 58%, P = .32). These early results establish Flu and melphalan 100 mg/m(2) with 2 Gy TBI or thiotepa 5 mg/kg as a very promising conditioning regimen for the treatment of advanced lymphoma with Haplo-SCT and PTCy.