Nonmyeloablative bone marrow transplantation from partially HLA-mismatched related donors using posttransplantation cyclophosphamide

Cohort-Controlled Comparison of Umbilical Cord Blood Transplantation Using Carlecortemcel-L, a Single Progenitor-Enriched Cord Blood, to Double Cord Blood Unit Transplantation

Umbilical cord blood (UCB) transplantation has a high early mortality rate primarily related to transplanted stem cell dose. To decrease early mortality and enhance engraftment, a portion of selected cord blood units (20% to 50%) was expanded with cytokines and the copper chelator tetraethylenepentamine (carlecortemcel-L) and transplanted with the unmanipulated fraction after myeloablative conditioning. The primary endpoint was 100-day survival, which was compared with a contemporaneous double-unit cord blood transplantation (DUCBT) group. We enrolled 101 patients at 25 sites; the DUCBT comparison (n = 295) was selected from international registries using study eligibility criteria. Baseline carlecortemcel-L study group unit nucleated cell (NC) and CD34⁺ were 3.06 × 10⁷ cell dose/kg and 1.64 × 10⁵ cell dose/kg. Median NC and CD34⁺ fold expansion were 400 and 77, with a mean total CD34 infused of 9.7 × 10⁵/kg. The 100-day survival was 84.2% for the carlecortemcel-L study group versus 74.6% for the DUCBT group (odds ratio, .50; 95% CI, .26 to .95; P = .035). Survival at day 180 was similar for the 2 groups; the major cause of death after day 100 was opportunistic infections. Faster median neutrophil (21 days versus 28 days; P < .0001), and platelet (54 days versus 105 days; P = .008) engraftment was seen in the carlecortemcel-L study group; acute and chronic graft-versus-host disease rates were similar. In this multinational comparative study, transplanting expanded CD34⁺ stem cells from a portion of a single UCB unit, with the remaining unmanipulated fraction improved 100-day survival compared with DUCBT control patients while facilitating myeloid and platelet engraftment. This trial was registered at www.clinicaltrials.gov as #NCT00469729.

Cooperation of CD4+ T cells and CD8+ T cells and release of IFN-γ are critical for antileukemia responses of recipient mice treated by microtransplantation

Previous studies have demonstrated that infusion of allogeneic matched and haploidentical peripheral blood stem cells with minimal conditioning (microtransplantation) achieved durable responses in patients with refractory leukemia/lymphoma in the absence of engraftment. The mechanisms underlying this response have not been thoroughly elucidated, while host-versus-graft reactions are likely to have an important role. The present study established a mismatched microtransplantation mouse model of leukemia to study the roles of CD4⁺ T cells and CD8⁺ T cells in changes of interferon (IFN)-γ and interleukin (IL)-4 release to explore the mechanisms of the effects of microtransplantation. It was demonstrated that IFN-γ is critical to the antileukemia response in a mouse model of microtransplantation. The therapeutic efficacy was associated with the number of CD4⁺ T cells (Pearson's r=0.722). In addition, CD8⁺ T cells increased the release of IFN-γ with assistance from CD4⁺ T cells. IL-2 augmented IFN-γ release, partly by increasing CD4⁺ T cells (42.8 vs. 35.6%; P<0.05). The present study suggested that the release of IFN-γ via cooperation of CD4⁺ T cells and CD8⁺ T cells represents a crucial mechanism in the antileukemia responses of recipient leukemic mice treated by microtransplantation. During this process, the cooperation of CD4⁺ T cells and CD8⁺ T cells was demonstrated to have a major role in the antileukemia effect. IL-2 may be developed into an agent used for improving the efficacy of microtransplantation by increasing CD4⁺ T cells.

Grade II Acute Graft-versus-Host Disease and Higher Nucleated Cell Graft Dose Improve Progression-Free Survival after HLA-Haploidentical Transplant with Post-Transplant Cyclophosphamide

Compared with standard graft-versus-host disease (GVHD) prophylaxis platforms, post-transplantation cyclophosphamide (PTCy) after T cell-replete HLA-haploidentical (haplo) bone marrow transplantation (BMT) reduces the risk of grades III to IV acute (a) and chronic (c) GVHD, but maintains similar rates of grade II aGVHD. Given that mild GVHD has been associated with reduced treatment failure in HLA-matched BMT, we evaluated the risk factors for and effects of GVHD on survival in 340 adults with hematologic malignancies who engrafted after nonmyeloablative haplo-BMT with PTCy, mycophenolate mofetil, and tacrolimus. The cumulative incidence at 100 days of grade II and grades III to IV aGVHD were 30% (95% confidence interval [CI], 25% to 35%) and 2% (95% CI, 1% to 4%), respectively. The 1-year cumulative incidence of cGVHD was 10% (95% CI, 7% to 13%). In landmark analyses at 100 days, the 4-year probabilities of overall survival (OS) and progression-free survival (PFS) were, 48% (95% CI, 41% to 56%) and 39% (95% CI, 32% to 47%) for patients without grades II to IV aGVHD, compared with 63% (95% CI, 53% to 73%) and 59% (95% CI, 50% to 71%) for patients with grade II aGVHD (P = .05 and P = .009). In multivariable modeling, when compared with patients who never experienced GVHD, the hazard ratio (HR) for OS and PFS in patients with grade II aGVHD was .78 (95% CI, .54 to 1.13; P = .19) and .69 (95% CI, .48 to .98; P = .04). Higher nucleated cell graft dose was also associated with improved OS (HR, .88; 95% CI, .78 to 1.00; P = .05) and PFS (HR, .89; 95% CI, .79 to 1.0; P = .05) and decreased risk of grades III to IV aGVHD (subdistribution HR, .66; 95% CI, .46 to .96; P = .03). PTCy reduces grades III to IV aGVHD and cGVHD, but retains similar incidence of grade II aGVHD, the development of which improves PFS. Higher nucleated cell graft dose goals may also improve survival after nonmyeloablative haplo-BMT with PTCy.

Hematopoietic stem cell transplantation for acute myeloid leukemia

Although allogeneic hematopoietic stem cell transplantation (allo-HSCT) yields a high rate of curability for acute myeloid leukemia (AML), it is also associated with transplant-related morbidity and mortality (TRM). The risk and severity of TRM increase with the use of an alternative donor graft in the absence of an HLA-matched sibling donor (MSD). With the declining birthrate and aging of the population, the numbers of patients with an MSD are decreasing, and alternative donor transplants, including the post-transplant cyclophosphamide method using haplo-identical donors, are increasing. Autologous (auto)-HSCT, which enables the intensification of chemotherapy, has the advantage of high availability of a transplant graft, and is associated with a lower TRM, but these benefits may be offset by a higher rate of relapse due to the lack of a graft-versus-leukemia (GVL) effect. Although allo-HSCT remains the first-line treatment for poor and very-poor-risk patients, auto-HSCT is again gaining increased attention. It has also recently been suggested that cord blood grafts may induce a stronger GVL effect than other grafts; as such, the positioning of cord blood transplantation should also be reconsidered for AML patients.

Alloantigen expression on malignant cells and healthy host tissue influences graft-versus-tumor reactions after allogeneic hematopoietic stem cell transplantation

Durable remissions of hematological malignancies regularly observed following allogeneic hematopoietic stem cell transplantation (aHSCT) are due to the conditioning regimen, as well as an immunological phenomenon called graft-versus-leukemia (GVL) or graft-versus-tumor (GVT) effect. The development of GVL is closely linked to graft-versus-host disease (GVHD), the main side effect associated with aHSCT. Both, GVHD and GVL are mediated by donor T cells that are initially activated by antigen-presenting cells that present recipient-derived alloantigens in the context of either matched or mismatched MHC class I molecules. Using murine models of aHSCT we show that ubiquitously expressed minor histocompatibility alloantigens (mHAg) are no relevant target for GVT effects. Interestingly, certain ubiquitously expressed MHC alloantigens augmented GVT effects early after transplantation, while others did not. The magnitude of GVT effects correlated with tumor infiltration by CD8+ cytotoxic T cells and tumor cell apoptosis. Furthermore, the immune response underlying GVHD and GVT was oligoclonal, highlighting that immunodominance is an important factor during alloimmune responses. These results emphasize that alloantigen expression on non-hematopoietic tissues can influence GVT effects in a previously unrecognized fashion. These findings bear significance for harnessing optimal GVL effects in patients receiving aHSCT.

Cyclophosphamide-induced tolerance in kidney transplantation avoids long-term immunosuppressive therapy

There has recently been remarkable progress in immunosuppressive agents, such as tacrolimus and cyclosporine. Therefore, the rate of organ establishment has improved in transplantation. However, immunosuppressive agents generally suppress the function of T cells. Thus, opportunistic infections, such as cytomegalovirus infection, are still a major problem in kidney transplantation. Induction of specific tolerance to avoid immunosuppressive drug therapy after kidney transplantation is considered as the ultimate goal of transplantation. Various factors induce tolerance that involves establishment of hematopoietic chimerism and various cell subsets. In particular, we have carried out various studies regarding the cyclophosphamide-induced tolerance system. Tolerance is induced after establishment of hematopoietic chimerism after donor bone marrow transplantation. At the clinical stage, kidney transplantation before administration of cyclophosphamide after transfusion of bone marrow to create hematopoietic chimera is considered to be one of the most successful protocols. Furthermore, recent studies have shown the involvement of multiple populations of immune cells in preserving immunological tolerance and promoting long-term renal grafts. The present review focuses on how cyclophosphamide and other immune factors induce tolerance in kidney transplantation.

Young donor white blood cell immunotherapy induces extensive tumor necrosis in advanced-stage solid tumors

Background

In the past decade, a variety of immunotherapy approaches focused predominantly on the adaptive immune system have shown unprecedented responses in patients with advanced-stage malignancies. However, studies in spontaneous regression/complete resistance (SR/CR) mice and humans have shown a novel innate cancer-killing activity mediated by granulocytes, which is completely transferable for prevention or therapy against established malignancies.

Methods

Three patients with advanced, relapsed or refractory solid tumors for which no standard therapy was available or was refused were enrolled into this ongoing combined phase I/II open label clinical trial testing the safety, dose tolerance, and possible antineoplastic efficacy of sequential infusions of HLA-mismatched non-irradiated allogeneic white cells (68–91% granulocytes) collected by leukapheresis from young, healthy donors (age 18–35) following mobilization with granulocyte colony stimulating factor (G-CSF) and dexamethasone.

Results

Besides fevers and flushing, no infusional toxicities were observed. All patients remained clinically stable following infusions with mild cytokine release syndrome and no evidence of transfusion-associated graft-versus-host disease, acute tumor lysis syndrome,or transfusion-associated acute lung injury. Pathological examination of all cases post-mortem revealed extensive tumor necrosis up to 80% in patients 1–2, 40–50% in patient 3, and leukocyte infiltration in all cases, which could not be attributed to disease progression.

Conclusions

Allogeneic white cell immunotherapy (AWIT) from young, healthy donors is well tolerated with minimal side effects and shows antitumor activity against advanced-stage solid tumors. AWIT represents a novel, safe, and cost-effective immunotherapy that can be administered in an outpatient cancer clinic.

T Cell-Depleted and T Cell-Replete HLA-Haploidentical Stem Cell Transplantation for Non-malignant Disorders

PURPOSE OF REVIEW

Hematopoietic stem cell transplantation (HSCT) is a treatment option for children with malignant and non-malignant disorders as well as an expanding number of inherited disorders. However, only a limited portion of patients in the need of an allograft have an HLA-compatible, either related or unrelated, donor. Haploidentical HSCT is now considered a valid treatment option, especially in view of the recent insights in terms of graft manipulation. This review will offer an overview of clinical results obtained through the use of haploidentical HSCT in non-malignant diseases. We will analyze major advantages and drawbacks of both T cell depleted and unmanipulated HSCT, discussing future challenges for further improving patients' outcome.

RECENT FINDINGS

T cell depletion (TCD) aims to reduce the morbidity and mortality associated with graft-versus-host disease (GvHD). However, the delayed immune recovery and the risk of graft failure still remain potential problems. In the last years, the use of post-transplant cyclophosphamide has been shown to be an alternative effective strategy to prevent GvHD in recipients of haploidentical HSCT. Recent data suggest that both T cell depleted and T cell-replete haplo-HSCT are suitable options to treat children with several types of non-malignant disorders lacking an HLA-identical donor.

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

Use 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.

Haploidentical hematopoietic cell transplantation for adult acute myeloid leukemia: a position statement from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

Allogeneic blood or marrow hematopoietic cell transplantation continues to be the most potent anti-leukemic treatment for adult patients with standard, high-risk, or chemo-refractory acute myeloid leukemia. Until recently, this procedure was generally limited to those recipients who had an available matched-sibling donor or matched-unrelated donor. Technical advances in graft cell processing and manipulation, control of bidirectional T cell alloreactivity, graft-versus-host disease prophylaxis, and other supportive measures in haploidentical transplantation now enable nearly all patients with acute myeloid leukemia to benefit from the graft-versus-leukemia effect with substantial reduction in procedure-related mortality. Over recent years, haploidentical donors have been increasingly adopted as a valid donor source in allogeneic hematopoietic cell transplantation for acute myeloid leukemia in the absence of an HLA-matched donor. Among centers of the European Society for Blood and Marrow Transplantation, the use of haploidentical related donor transplantation has increased by 250% since 2010, and 291% since 2005. On behalf of the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation, we summarize recent utilization trends in haploidentical transplantation for acute myeloid leukemia and describe the transformative changes in haploidentical hematopoietic cell transplantation techniques over the past decade, which have led to the current widespread use of this procedure. Furthermore, we review the efficacy of haploidentical hematopoietic cell transplantation for acute myeloid leukemia from available studies, including preliminary comparative studies, and bring attention to remaining unanswered questions and directions for future research. We conclude this report with our recommendations for the role of haploidentical hematopoietic cell transplantation in acute myeloid leukemia.

Role of metabolites of cyclophosphamide in cardiotoxicity

Background

The dose-limiting toxic effect of cyclophosphamide (CY) is cardiotoxicity. The pathogenesis of myocardial damage is poorly understood, and there is no established means of prevention. In previous studies, we suggested that for CY-induced cardiotoxicity, whereas acrolein is the key toxic metabolite, carboxyethylphosphoramide mustard (CEPM) is protective. We sought to verify that acrolein is the main cause of cardiotoxicity and to investigate whether aldehyde dehydrogenase (ALDH), which is associated with greater CEPM production, is involved in the protective effect for cardiotoxicity. We also evaluated the protective effect of N-acetylcysteine (NAC), an amino acid with antioxidant activity and a known acrolein scavenger.

Methods

H9c2 cells were exposed to CY metabolites HCY (4-hydroxy-cyclophosphamide), acrolein or CEPM. The degree of cytotoxicity was evaluated by MTT assay, lactate dehydrogenase (LDH) release, and the production of reactive oxygen species (ROS). We also investigated how the myocardial cellular protective effects of CY metabolites were modified by NAC. To quantify acrolein levels, we measured the culture supernatants using high performance liquid chromatography. We measured ALDH activity after exposure to HCY or acrolein and the same with pre-treatment with NAC.

Results

Exposure of H9c2 cells to CEPM did not cause cytotoxicity. Increased ROS levels and myocardial cytotoxicity, however, were induced by HCY and acrolein. In cell cultures, HCY was metabolized to acrolein. Less ALDH activity was observed after exposure to HCY or acrolein. Treatment with NAC reduced acrolein concentrations.

Conclusions

Increased ROS generation and decreased ALDH activity confirmed that CY metabolites HCY and acrolein are strongly implicated in cardiotoxicity. By inhibiting ROS generation, increasing ALDH activity and decreasing the presence of acrolein, NAC has the potential to prevent CY-induced cardiotoxicity.

Major Histocompatibility Mismatch and Donor Choice for Second Allogeneic Bone Marrow Transplantation

Large alternative donor pools provide the potential for selecting a different donor for a second allogeneic (allo) bone or marrow transplant (BMT). As HLA disparity may contribute to the graft-versus-tumor effect, utilizing new mismatched haplotype donors may potentially improve the antitumor activity for relapsed hematologic malignancies despite a previous alloBMT. Data from patients who received a second alloBMT for relapsed hematologic malignancies at Johns Hopkins were analyzed. Outcomes were compared between patients who received a second allograft with the same MHC composition and those who received an allograft with a new mismatched haplotype. Loss of heterozygosity analysis was performed for patients with acute myeloid leukemia (AML) whose first allograft was haploidentical. Between 2005 and 2015, 40 patients received a second BMT for a relapsed hematologic malignancy. The median follow-up is 750 (range, 26 to 2950) days. The median overall survival (OS) in the cohort is 928 days (95% confidence interval [CI], 602 to not reached [NR]); median event-free survival (EFS) for the cohort is 500 days (95% CI, 355 to NR). The 4-year OS is 40% (95% CI, 25% to 64%), and the 4-year EFS is 36% (95% CI, 24% to 55%). The cumulative incidence of nonrelapsed mortality by 2 years was 27% (95% CI, 13% to 42%). The cumulative incidence of grade 3 to 4 acute graft-versus-host disease (GVHD) at 100 days was 15% (95% CI, 4% to 26%); the cumulative incidence of extensive chronic GVHD at 2 years was 22% (95% CI, 9% to 36%). The median survival was 552 days (95% CI, 376 to 2950+) in the group who underwent transplantation with a second allograft that did not harbor a new mismatched haplotype, while it was not reached in the group whose allograft contained a new mismatched haplotype (hazard ratio [HR], .36; 95% CI, .14 to .9; P = .02). EFS was also longer in the group who received an allograft containing a new mismatched haplotype, (NR versus 401 days; HR, .50; 95% CI, .22 to 1.14; P = .09). Although the allograft for this patient's second BMT contained a new mismatched haplotype, AML nevertheless relapsed a second time. Second BMTs are feasible and provide a reasonable chance of long-term survival. An allograft with a new mismatched haplotype may improve outcomes after second BMTs for relapsed hematologic malignancies.

Allogeneic Blood or Marrow Transplantation with Post-Transplantation Cyclophosphamide as Graft-versus-Host Disease Prophylaxis in Multiple Myeloma

Allogeneic blood or marrow transplantation (alloBMT) may lead to long-term disease control in patients with multiple myeloma (MM). However, historically, the use of alloBMT in MM has been limited by its high nonrelapse mortality (NRM) rates, primarily from graft-versus-host disease (GVHD). We previously demonstrated that post-transplantation cyclophosphamide (PTCy) decreases the toxicities of both acute and chronic GVHD after alloBMT. Here, we examine the impact of PTCy in patients with MM undergoing alloBMT at Johns Hopkins Hospital. From 2003 to 2011, 39 patients with MM underwent bone marrow or peripheral blood alloBMT from HLA-matched related/unrelated or haploidentical related donors after either myeloablative or nonmyeloablative conditioning. Post-transplantation GVHD prophylaxis consisted of cyclophosphamide (50 mg/kg) on days +3 and +4 with or without mycophenolate mofetil and tacrolimus. Engraftment was detected in 95% of patients, with neutrophil and platelet recovery at a median of 15 and 16 days, respectively. The cumulative incidences of acute grades 2 to 4 and grades 3 and 4 GVHD were .41 and .08, respectively, and no cases of grade 4 acute GVHD were observed. The cumulative incidence of chronic GVHD was .13. One patient succumbed to NRM. All cases of chronic GVHD involved extensive disease and 60% of these patients received systemic therapy with complete resolution. After alloBMT, the overall response rate was 62% with complete, very good partial, and partial response rates of 26%, 21%, and 15%, respectively. The median progression-free survival was 12 months and was associated with the depth of response but not cytogenetic risk. The estimated cumulative incidence of relapse was .46 (95% confidence interval [CI], .3 to .62) at 1 year and .56 (95% CI, .41 to .72) at 2 years. At last follow-up, 23% of patients remain without evidence of disease at a median follow-up of 10.3 years after alloBMT. The median overall survival was 4.4 years and the 5-year and 10-year overall survival probabilities were 49% (95% CI, 35% to 67%) and 43% (95% CI, 29% to 62%), respectively. The use of PTCy after alloBMT for MM is feasible and results in low NRM and GVHD rates. The safety of this approach may allow the development of novel post-transplantation maintenance strategies to improve long-term disease control.

Mobilized Peripheral Blood Stem Cells Versus Unstimulated Bone Marrow As a Graft Source for T-Cell-Replete Haploidentical Donor Transplantation Using Post-Transplant Cyclophosphamide

Purpose T-cell-replete HLA-haploidentical donor hematopoietic transplantation using post-transplant cyclophosphamide was originally described using bone marrow (BM). With increasing use of mobilized peripheral blood (PB), we compared transplant outcomes after PB and BM transplants. Patients and Methods A total of 681 patients with hematologic malignancy who underwent transplantation in the United States between 2009 and 2014 received BM (n = 481) or PB (n = 190) grafts. Cox regression models were built to examine differences in transplant outcomes by graft type, adjusting for patient, disease, and transplant characteristics. Results Hematopoietic recovery was similar after transplantation of BM and PB (28-day neutrophil recovery, 88% v 93%, P = .07; 100-day platelet recovery, 88% v 85%, P = .33). Risks of grade 2 to 4 acute (hazard ratio [HR], 0.45; P < .001) and chronic (HR, 0.35; P < .001) graft-versus-host disease were lower with transplantation of BM compared with PB. There were no significant differences in overall survival by graft type (HR, 0.99; P = .98), with rates of 54% and 57% at 2 years after transplantation of BM and PB, respectively. There were no differences in nonrelapse mortality risks (HR, 0.92; P = .74) but relapse risks were higher after transplantation of BM (HR, 1.49; P = .009). Additional exploration confirmed that the higher relapse risks after transplantation of BM were limited to patients with leukemia (HR, 1.73; P = .002) and not lymphoma (HR, 0.87; P = .64). Conclusion PB and BM grafts are suitable for haploidentical transplantation with the post-transplant cyclophosphamide approach but with differing patterns of treatment failure. Although, to our knowledge, this is the most comprehensive comparison, these findings must be validated in a randomized prospective comparison with adequate follow-up.

T-Cell Manipulation Strategies to Prevent Graft-Versus-Host Disease in Haploidentical Stem Cell Transplantation

Allogeneic haematopoietic stem cell transplantation (HSCT) from an human leukocyte antigen (HLA)-identical donor can be curative for eligible patients with non-malignant and malignant haematological disorders. HSCT from alternative donor sources, such as HLA-mismatched haploidentical donors, is increasingly considered as a viable therapeutic option for patients lacking HLA-matched donors. Initial attempts at haploidentical HSCT were associated with vigorous bidirectional alloreactivity, leading to unacceptably high rates of graft rejection and graft-versus-host disease (GVHD). More recently, new approaches for mitigating harmful T-cell alloreactivity that mediates GVHD, while preserving the function of tumour-reactive natural killer (NK) cells and γδ T cells, have led to markedly improved clinical outcomes, and are successfully being implemented in the clinic. This article will provide an update on in vitro strategies and in vivo approaches aimed at preventing GVHD by selectively manipulating key components of the adaptive immune response, such as T-cell receptor (TCR)-αβ T cells and CD45RA-expressing naive T cells.

Single-agent GvHD prophylaxis with tacrolimus after post-transplant high-dose cyclophosphamide is a valid option for haploidentical transplantation in adults with hematological malignancies

Eighty-one patients with high-risk hematological malignancies received unmanipulated haploidentical stem cell transplants (haploSCT) using the same protocol at four Spanish institutions. The conditioning regimen was thiotepa, busulfan and fludarabine; following bone marrow or peripheral blood infusion. GvHD prophylaxis with high-dose cyclophosphamide on days +3 and +4, and IV tacrolimus from day +5 was administered. 62% were in complete remission, 17% had received previous allogeneic SCT and 44% had a high-very high refined disease risk index. One patient had primary graft failure and three more died before +21. The median days to neutrophil and platelet recoveries were +18 and +23, respectively, and 93% achieved a full donor chimerism on day +30. At 1 year, cumulative incidences (CumInc) of non-relapse mortality and relapse were 27 and 19%. One-year overall survival and PFS were 61 and 51%. CumInc of grade II-IV and III-IV were 23 and 14%. At 30 months, CumInc of limited and extensive GvHD were 20 and 22%. In conclusion, patients with hematological malignancies who receive an unmanipulated haploSCT with post-transplant cyclophosphamide may benefit from less intense pharmacological prophylaxis for GvHD prophylaxis. Whether this approach potentiates the graft-versus-tumor effect and decreases relapses requires further investigation.

Cyclophosphamide improves engraftment in patients with SCD and severe organ damage who undergo haploidentical PBSCT

Peripheral blood stem cell transplantation (PBSCT) offers a curative option for sickle cell disease (SCD). Although HLA-matched sibling transplantation is promising, the vast majority of patients lack such a donor. We sought to develop a novel nonmyeloablative HLA-haploidentical PBSCT approach that could safely be used for patients with severe organ damage. Based on findings in our preclinical model, we developed a phase 1/2 trial using alemtuzumab, 400 cGy total body irradiation, and escalating doses of posttransplant cyclophosphamide (PT-Cy): 0 mg/kg in cohort 1, 50 mg/kg in cohort 2, and 100 mg/kg in cohort 3. A total of 21 patients with SCD and 2 with β-thalassemia received a transplant. The mean hematopoietic cell transplant-specific comorbidity index of 6 reflected patients with cirrhosis, heart failure, and end-stage renal disease. The engraftment rate improved from 1 (33%) of 3 in cohort 1 to 5 (63%) of 8 in cohort 2 and 10 (83%) of 12 in cohort 3. Percentage of donor myeloid and CD3 chimerism also improved with subsequent cohorts. There was no transplant-related mortality, and overall survival was 87%. At present, 0% in cohort 1, 25% in cohort 2, and 50% in cohort 3 remain free of their disease. There was no grade 2 to 4 acute or extensive chronic graft-versus-host disease (GVHD). Therefore, PT-Cy improves engraftment and successfully prevents severe GVHD after nonmyeloablative conditioning in patients with SCD who are at high risk for early mortality. Additional strategies are necessary to decrease the graft rejection rate and achieve a widely available cure for all patients with SCD. This trial was registered at www.clinicaltrials.gov as #NCT00977691.

Cytogenetics and comorbidity predict outcomes in older myelodysplastic syndrome patients after allogeneic stem cell transplantation using reduced intensity conditioning

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only treatment with a curative potential for myelodysplastic syndrome (MDS) patients. Allo-HSCT has substantial risks, particularly in the elderly, and its role for older MDS patients has yet to be defined.

METHODS

We analyzed 88 MDS patients aged ≥ 60 years with allo-HSCT after reduced intensity conditioning regimens over the last decade. The study cohort had high risk features; 47 of 88 (53.4%) patients were > 65 years of age, 24 (27%) patients had cytogenetic abnormalities consistent with monosomal karyotype (MKpos), 33 (38%) patients had histological subtype of RAEB-1 and RAEB-2 at diagnosis, and 45 (51%) patients had a hematopoietic cell transplantation-comorbidity index (HCT-CI) of ≥ 3.

RESULTS

The 3-year incidence of progression, transplant-related mortality (TRM), and overall survival (OS) were 26% (95% confidence interval [CI], 18%-37%), 35% (95% CI, 26%-47%), and 41% (95% CI, 30%-52%), respectively. MKpos was the only prognostic factor that increased the risk of disease progression compared with good-risk cytogenetics (hazard ratio [HR] = 9.5, P = .003) as well as MKneg (HR = 3.3, P = .01). For TRM, HCT-CI ≥ 3, but not age >65 years, was associated with worse outcomes (HR = 3.1, P = .007). Cytogenetics and HCT-CI enabled us to identify prognostic groups for OS. MKpos patients had the worst 3-year OS (17%), whereas patients with good-risk cytogenetics and HCT-CI < 3 had the best OS (92%).

CONCLUSION

Our results confirm that allo-HSCT can provide long-term survival in older MDS patients. Cytogenetics and HCT-CI identify prognostic risk groups and guide selection of older MDS patients who are candidates for allo-HSCT. Cancer 2017;123:2661-70. © 2017 American Cancer Society.

Related haploidentical donors are a better choice than matched unrelated donors: Counterpoint

Publisher's Note: This article has a companion Point by Fuchs. Publisher's Note: Join in the discussion of these articles at Blood Advances Community Conversations.

T Cell-Replete Peripheral Blood Haploidentical Hematopoietic Cell Transplantation with Post-Transplantation Cyclophosphamide Results in Outcomes Similar to Transplantation from Traditionally Matched Donors in Active Disease Acute Myeloid Leukemia

Outcomes for patients with acute myeloid leukemia (AML) who fail to achieve complete remission remain poor. Hematopoietic cell transplantation (HCT) has been shown to induce long-term survival in AML patients with active disease. HCT is largely performed with HLA-matched unrelated or HLA-matched related donors. Recently, HCT with HLA-haploidentical related donors has been identified as a feasible option when HLA-matched donors are not immediately available. However, there are little data comparing outcomes for AML patients with active disease who receive haploidentical versus traditionally matched HCT. We retrospectively analyzed data from 99 AML patients with active disease undergoing allogeneic HCT at a single institution. Forty-three patients received unrelated donor HCT, 32 patients received matched related donor HCT, and 24 patients received peripheral blood haploidentical HCT with post-transplantation cyclophosphamide. We found no significant differences between treatment groups in terms of overall survival (OS), event-free survival, transplantation-related mortality, cumulative incidence of relapse, and cumulative incidence of acute and chronic graft-versus-host disease (GVHD). We performed univariate regression analysis of variables that modified OS in all patients and found only younger age at transplantation and development of chronic GVHD significantly improved outcome. Although limited by our relatively small sample size, these results indicate that haploidentical HCT in active AML patients have comparable outcomes to HCT with traditionally matched donors. Haploidentical HCT can be considered in this population of high-risk patients when matched donors are unavailable or when wait times for transplantation are unacceptably long.

Dose-adapted post-transplant cyclophosphamide for HLA-haploidentical transplantation in Fanconi anemia

We developed a haploidentical transplantation protocol with post-transplant cyclophosphamide (CY) for in vivo T-cell depletion using a novel adapted-dosing schedule (25 mg/kg on days +3 and +4) for Fanconi Anemia. With median follow-up of 3 years (range, 37 days to 6.2 years), all six patients engrafted. Two patients with multiple co-morbidities and late referrals to transplant died from sepsis (n=2) and chronic graft-versus-host disease (GVHD) (n=1). Four patients without pre-existing co-morbidities and early transplant referrals are alive with 100% donor chimerism and excellent performance status. We conclude that modulated-dosing post-transplant CY is effective in vivo T-cell depletion to promote full donor engraftment in patients with Fanconi anemia.

Pharmacokinetics, Pharmacodynamics and Pharmacogenomics of Immunosuppressants in Allogeneic Haematopoietic Cell Transplantation: Part I

Although immunosuppressive treatments and target concentration intervention (TCI) have significantly contributed to the success of allogeneic haematopoietic cell transplantation (alloHCT), there is currently no consensus on the best immunosuppressive strategies. Compared with solid organ transplantation, alloHCT is unique because of the potential for bidirectional reactions (i.e. host-versus-graft and graft-versus-host). Postgraft immunosuppression typically includes a calcineurin inhibitor (cyclosporine or tacrolimus) and a short course of methotrexate after high-dose myeloablative conditioning, or a calcineurin inhibitor and mycophenolate mofetil after reduced-intensity conditioning. There are evolving roles for the antithymyocyte globulins (ATGs) and sirolimus as postgraft immunosuppression. A review of the pharmacokinetics and TCI of the main postgraft immunosuppressants is presented in this two-part review. All immunosuppressants are characterized by large intra- and interindividual pharmacokinetic variability and by narrow therapeutic indices. It is essential to understand immunosuppressants' pharmacokinetic properties and how to use them for individualized treatment incorporating TCI to improve outcomes. TCI, which is mandatory for the calcineurin inhibitors and sirolimus, has become an integral part of postgraft immunosuppression. TCI is usually based on trough concentration monitoring, but other approaches include measurement of the area under the concentration-time curve (AUC) over the dosing interval or limited sampling schedules with maximum a posteriori Bayesian personalization approaches. Interpretation of pharmacodynamic results is hindered by the prevalence of studies enrolling only a small number of patients, variability in the allogeneic graft source and variability in postgraft immunosuppression. Given the curative potential of alloHCT, the pharmacodynamics of these immunosuppressants deserves to be explored in depth. Development of sophisticated systems pharmacology models and improved TCI tools are needed to accurately evaluate patients' exposure to drugs in general and to immunosuppressants in particular. Sequential studies, first without and then with TCI, should be conducted to validate the clinical benefit of TCI in homogenous populations; randomized trials are not feasible, because there are higher-priority research questions in alloHCT. In Part I of this article, we review the alloHCT process to facilitate optimal design of pharmacokinetic and pharmacodynamics studies. We also review the pharmacokinetics and TCI of calcineurin inhibitors and methotrexate.

Anti-thymocyte globulin as graft-versus-host disease prevention in the setting of allogeneic peripheral blood stem cell transplantation: a review from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

Allogeneic hematopoietic stem cell transplantation is increasingly used as treatment for patients with life-threatening blood diseases. Its curative potential is largely based on immune-mediated graft-versus-leukemia effects caused by donor T cells contained in the graft. Unfortunately, donor T cells are also the cause of graft-versus-host disease. The vast majority of human leukocyte antigen-matched allogeneic hematopoietic stem cell transplants are nowadays carried out with peripheral blood stem cells as the stem cell source. In comparison with bone marrows, peripheral blood stem cells contain more hematopoietic stem/progenitor cells but also one log more T cells. Consequently, the use of peripheral blood stem cells instead of bone marrow has been associated with faster hematologic recovery and a lower risk of relapse in patients with advanced disease, but also with a higher incidence of chronic graft-versus-host disease. These observations have been the basis for several studies aimed at assessing the impact of immunoregulation with anti-thymocyte globulin on transplantation outcomes in patients given human leukocyte antigen-matched peripheral blood stem cells from related or unrelated donors. After a brief introduction on anti-thymocyte globulin, this article reviews recent studies assessing the impact of anti-thymocyte globulin on transplantation outcomes in patients given peripheral blood stem cells from human leukocyte antigen-matched related or unrelated donors as well as in recipients of grafts from human leukocyte antigen haploidentical donors.

Haploidentical peripheral blood stem cell transplantation with posttransplant cyclophosphamide in children and adolescents with hematological malignancies

BACKGROUND

Haploidentical hematopoietic stem cell transplantation (haplo-HSCT) using posttransplant cyclophosphamide (Cy) for graft versus host disease (GVHD) prophylaxis has emerged as an alternative transplant strategy for patients without related donors, especially in the setting of limited resources in which T-cell ex vivo depletion is not affordable. Experience with this transplant modality in children and adolescents is limited.

PROCEDURE

We report a retrospective analysis of 25 consecutive outpatients under 21 years of age with high-risk hematological malignancies, who received a haplo-HSCT using posttransplant Cy as GVHD prophylaxis.

RESULTS

Twenty-three (92%) of the 25 patients engrafted, and 20 (95%) of 21 evaluable subjects achieved full donor chimerism by day +30. One-year estimated overall survival and event-free survival were 50% and 33%, respectively. The cumulative incidence rate of severe acute GVHD was 19%, and 15% of patients developed chronic GVHD.

CONCLUSIONS

Haplo-HSCT with posttransplant Cy is a feasible therapeutic option for children and adolescents with high-risk hematological malignancies in a limited resource setting.

Allogeneic Stem Cell Transplantation: A Historical and Scientific Overview

The field of hematopoietic stem cell transplant (HSCT) has made ground-breaking progress in the treatment of many malignant and nonmalignant conditions. It has also pioneered the concepts of stem cell therapy and immunotherapy as a tool against cancer. The success of transplant for hematologic malignancies derives both from the ability to treat patients with intensive chemoradiotherapy and from potent graft-versus-leukemia (GVL) effects mediated by donor immunity. Additionally, HSCT has been a curative therapy for several nonmalignant hematologic disorders through the provision of donor-derived hematopoiesis and immunity. Preclinical and clinical research in the field has contributed to an advanced understanding of histocompatibility, graft-versus-host disease (GVHD), GVL effect, and immune reconstitution after transplant. Improved donor selection, tailored conditioning regimens, and better supportive care have helped reduce transplant-related morbidity and mortality and expanded access. The development of unrelated donor registries and increased utilization of cord blood and partially matched related donor transplants have ensured a donor for essentially everyone who needs a transplant. However, significant barriers still remain in the form of disease relapse, GVHD infectious complications, and regimen-related toxicities. Recent developments in the field of cellular therapy are expected to further improve the efficacy of transplant. In this review, we discuss the current science of HSCT from a historical perspective, highlighting major discoveries. We also speculate on future directions in this field. Cancer Res; 76(22); 6445-51. ©2016 AACR.

First Successful Haploidentical Stem Cell Transplantation in Romania

Hematopoietic stem cell transplantation is an established treatment for many malignant and non-malignant haematological disorders. In the current case report, we describe the first haploidentical stem cell transplantation, used for the first time in Romania, the case of a 33 year-old young woman diagnosed with Hodgkin's lymphoma that has underwent a haploSCT after she relapsed from several chemotherapy regimens, as well as after an autologous stem cell transplantation. This success represents a prèmiere in Romanian clinical hematology, being the first case of a haploSCT in Romania, as well as in South-Eastern Europe.

Haploidentical transplantation in children with unmanipulated peripheral blood stem cell graft: The need to look beyond post-transplantation cyclophosphamide in younger children

Haploidentical transplantation with PTCY following marrow or PBSC graft has been associated with low incidence of GVHD in adults with similar data lacking in children. We report on the outcome of 25 patients <20 yr of age (median age 12 yr), undergoing a haploidentical PBSC transplantation for both malignant and non-malignant disorders. Engraftment was prompt and sustained. Cumulative incidences of acute GVHD and chronic GVHD were 40.3% and 16.7%, respectively. On subgroup analysis, it was evident that acute GVHD developed in 80% of patients <10 yr compared to only 13.3% in those between 10 and 20 yr [log-rank p = 0.001], despite similar graft composition with significantly higher NRM (60% vs. 0%; p = 0.001). The FFS was 63.5%; (79% in >10 yr and 40% in <10 yr, p = 0.01). Our data suggest that PTCY-based haploidentical PBSC transplantation is feasible in older children, but results in early and severe alloreactivity in younger children. These findings, despite being counterintuitive, could be explained by the variable metabolism of CY and oral mycophenolate in younger children indicating that PTCY-based approach as used in adults might not be adequate for younger children.

Comparable Allogeneic Hematopoietic Cell Transplantation Outcome of a Haplo-Identical Family Donor with an Alternative Donor in Adult Aplastic Anemia

We performed a study on allogeneic hematopoietic cell transplantation (alloHCT) from an HLA-haplo-identical familial donor (haploFD) using a busulfan-fludarabine-antithymocyte globulin conditioning regimen for severe aplastic anemia (sAA) and hypoplastic myelodysplastic syndrome. For the comparison between a haploFD and an alternative donor (AD; matched unrelated or partially matched donor) for sAA in adults, we collected haploFD data retrospectively and prospectively. Forty-eight AD cases were selected for the comparison with 16 haploFD cases. All transplantation outcomes except for extensive chronic graft versus host disease (GvHD) were similar. The frequencies of hepatic sinusoidal obstruction syndrome (p = 1.000), acute GvHD (p = 0.769), grade 3/4 acute GvHD (p = 0.258), chronic GvHD (p = 0.173), extensive chronic GvHD (p = 0.099), primary neutrophil engraftment failure (p = 1.000), secondary graft failure (p = 1.000) and platelet engraftment failure (p = 0.505) were similar. Time to neutrophil engraftment was faster in haploFD (p = 0.003), while the cumulative incidence of platelet engraftment was similar (p = 0.505). Overall survival was also similar between AD and haploFD (p = 0.730). In conclusion, alloHCT from haploFD in sAA was comparable with alloHCT from AD, but extensive chronic GvHD seemed frequent in haploFD. Therefore alloHCT from haploFD could be an alternative approach for alloHCT from AD in adult sAA.

Comparison of Outcomes after Peripheral Blood Haploidentical versus Matched Unrelated Donor Allogeneic Hematopoietic Cell Transplantation in Patients with Acute Myeloid Leukemia: A Retrospective Single-Center Review

Recent studies comparing allogeneic hematopoietic cell transplantation (HCT) using HLA-matched unrelated donors (MUD) versus HLA-haploidentical donors in patients with acute myeloid leukemia (AML) have suggested equivalent outcomes. The graft source used in most studies of haploidentical transplants has been bone marrow. Similar comparisons between MUD and haplo-HCT using peripheral blood as a graft source have not been adequately performed. We reviewed the records of all 52 AML patients who underwent haplo-HCT (using peripheral blood and post-transplantation high-dose cyclophosphamide) between January 2010 and August 2015 at our institution and compared their outcomes with 88 patients who had a MUD transplant in the same time frame and were frequency matched (preanalysis) to the haploidentical group for conditioning intensity. Multivariate analysis found no difference in outcomes between the 2 groups with the exception of slower count recovery after haploidentical allografts (HR, .48; 95% CI, .32 to .74 for platelets, and HR, .47; 95% CI, .32 to .71 for neutrophils; P < .001 for both comparisons). Our retrospective analysis, although limited by the small sample size, suggests largely similar outcomes with peripheral blood haploidentical versus MUD transplants for AML.

Advances in haploidentical stem cell transplantation for hematologic malignancies

One of the most important advances in allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the use of alternative donors and cell sources, such as haploidentical transplants (haplo-HSCT) from family donors. Several approaches have been developed to overcome the challenging bidirectional alloreactivity. We discuss these approaches, including ex vivo T-cell-depleted grafts with megadose of CD34(+) cells, not requiring immunosuppression after allogeneic transplantation for graft-versus-host disease (GVHD) prophylaxis, and other strategies using unmanipulated T-cell-replete grafts with intensive immunosuppression or post-transplantation cyclophosphamide to minimize the GVHD. We also address the role of other strategies developed in the context of the haplo-HSCT platforms, such as ex vivo selective depletion of alloreactive donor T-cell subpopulations, infusion of antigen-specific T-cells against several pathogens, and infusion of regulatory T-cells, among other experimental approaches. Finally, some considerations about the selection of the most suitable donor, when more than one family member is available, are also addressed.

HLA Haplotype Mismatch Transplants and Posttransplant Cyclophosphamide

The use of high dose posttransplant cyclophosphamide (PT-CY) introduced by the Baltimore group approximately 10 years ago has been rapidly adopted worldwide and is becoming a standard for patients undergoing unmanipulated haploidentical (HAPLO) transplants. PT-CY has been used following nonmyeloablative as well as myeloablative conditioning regimens, for bone marrow or peripheral blood grafts, for patients with malignant and nonmalignant disorders. Retrospective comparisons of HAPLO grafts with conventional sibling and unrelated donor grafts have been published and suggest comparable outcome. The current questions to be answered include the use of PT-CY for sibling and unrelated donors transplant, possibly in the context of prospective randomized trial.

Antithymocyte globulin in allogeneic hematopoietic cell transplantation: benefits and limitations

Significant advances have been made in allogeneic hematopoietic cell transplantation by reducing toxicities and optimizing its efficacy. Antithymocyte globulin (ATG) is an important in vivo T-cell depletion strategy, which reduces the risk of graft-versus-host disease in HLA-matched or -mismatched donor allografting. ATG effectively targets alloreactive T cells at the expense of potentially increasing the risk of post-hematopoietic cell transplantation infections and delayed immune reconstitution. We summarize the targets, mechanisms, various preparations of ATG, the growing role of ATG in prevention of graft-versus-host disease in various transplant modalities as well as emerging data on pharmacokinetic modeling for individualized ATG dosing. Further research is needed to optimize the ATG administration while minimizing the toxicities.

Choice of Unmanipulated T Cell Replete Graft for Haploidentical Stem Cell Transplant and Posttransplant Cyclophosphamide in Hematologic Malignancies in Adults: Peripheral Blood or Bone Marrow-Review of Published Literature

Allogeneic hematopoietic stem cell transplantation (SCT) is often the only curative option for many patients with malignant and benign hematological stem cell disorders. However, some issues are still of concern regarding finding a donor like shrinking family sizes in many societies, underrepresentation of the ethnic minorities in the registries, genetic variability for some races, and significant delays in obtaining stem cells after starting the search. So there is a considerable need to develop alternate donor stem cell sources. The rapid and near universal availability of the haploidentical donor is an advantage of the haploidentical SCT and an opportunity that is being explored currently in many centers especially using T cell replete graft and posttransplant cyclophosphamide. This is probably because it does not require expertise in graft manipulation and because of the lower costs. However, there are still lots of unanswered questions, like the effect of use of bone marrow versus peripheral blood as the source of stem cells on graft-versus-host disease, graft versus tumor, overall survival, immune reconstitution, and quality of life. Here we review the available publications on bone marrow and peripheral blood experience in the haploidentical SCT setting.