Younger unrelated donors may be preferable over HLA match in the PTCy era: a study from the ALWP of the EBMT.

ABSTRACT: There is a paucity of information on how to select the most appropriate unrelated donor (UD) in hematopoietic stem cell transplantation (HSCT) using posttransplant cyclophosphamide (PTCy). We retrospectively analyzed the characteristics of 10/10 matched UDs (MUDs) and 9/10 mismatched UDs (MMUDs) that may affect transplant outcomes in patients with acute myeloid leukemia (AML) in first or second complete remission (CR1 or CR2). The primary end point was leukemia-free survival (LFS). Overall, 1011 patients were included with a median age of 54 years (range, 18-77). Donors had a median age of 29 years (range, 18-64); 304 (30%) were females, of which 150 (15% of the whole group) were donors to male recipients, and 621 (61%) were MUDs; 522 (52%) had negative cytomegalovirus (CMV-neg) serostatus, of which 189 (19%) were used for CMV-neg recipients. Donor age older than 30 years had a negative impact on relapse (hazard ratio [HR], 1.38; 95% confidence interval [CI], 1.06-1.8), LFS (HR, 1.4; 95% CI, 1.12-1.74), overall survival (HR 1.45; 95% CI, 1.14-1.85) and graft-versus-host disease (GVHD) free, relapse-free survival (HR, 1.29; 95% CI, 1.07-1.56). In addition, CMV-neg donors for CMV-neg recipients were associated with improved LFS (HR, 0.74; 95% CI, 0.55-0.99). The use of MMUD and female donors for male recipients did not significantly impact any transplant outcomes. For patients undergoing HSCT from a UD with PTCy for AML, donor age <30 years significantly improves survival. In this context, donor age might be prioritized over HLA match considerations. In addition, CMV-neg donors are preferable for CMV-neg recipients. However, further research is needed to validate and refine these recommendations.

Engineering of CD34+ progenitor-derived natural killer cells with higher-affinity CD16a for enhanced antibody-dependent cellular cytotoxicity.

BACKGROUND AIMS: Natural killer (NK) cell transfer is a promising cellular immunotherapy for cancer. Previously, we developed a robust method to generate large NK cell numbers from CD34+ hematopoietic stem and progenitor cells (HSPCs), which exhibit strong anti-tumor activity. However, since these cells express low levels of the Fc receptor CD16a in vitro, antibody-dependent cellular cytotoxicity (ADCC) by these cells is limited. To broaden clinical applicability of our HSPC-NK cells toward less NK-sensitive malignancies, we aimed to improve ADCC through CD16a transduction. METHODS: Using wildtype and S197P mutant greater-affinity (both with V158) CD16a retroviral transgenes (i.e., a cleavable and noncleavable CD16a upon stimulation), we generated CD16a HSPC-transduced NK cells, with CD34+ cells isolated from umbilical cord blood (UCB) or peripheral blood after G-CSF stem cell mobilization (MPB). CD16a expressing NK cells were enriched using flow cytometry-based cell sorting. Subsequently, phenotypic analyses and functional assays were performed to investigate natural cytotoxicity and ADCC activity. RESULTS: Mean transduction efficiency was 34% for UCB-derived HSPCs and 20% for MPB-derived HSPCs, which was enriched by flow cytometry-based cell sorting to >90% for both conditions. Expression of the transgene remained stable during the entire NK expansion cell generation process. Proliferation and differentiation of HSPCs were not hampered by the transduction process, resulting in effectively differentiated CD56+ NK cells after 5 weeks. Activation of the HSPC-derived NK cells resulted in significant shedding of wildtype CD16a transcribed from the endogenous gene, but not of the noncleavable mutant CD16a protein expressed from the transduced construct. The mean increase of CD107+IFNγ+ expressing NK cells after inducing ADCC was tenfold in enriched noncleavable CD16a HSPC-NK cells. Killing capacity of CD16a-transduced NK cells was significantly improved after addition of a tumor-targeting antibody in tumor cell lines and primary B-cell leukemia and lymphoma cells compared to unmodified HSPC-NK cells. CONCLUSIONS: Together, these data demonstrate that the applicability of adoptive NK cell immunotherapy may be broadened to less NK-sensitive malignancies by upregulation of CD16a expression in combination with the use of tumor-targeting monoclonal antibodies.

Human CD34+-derived complete plasmacytoid and conventional dendritic cell vaccine effectively induces antigen-specific CD8+ T cell and NK cell responses in vitro and in vivo.

Allogeneic stem cell transplantation (alloSCT) can be curative for hemato-oncology patients due to effective graft-versus-tumor immunity. However, relapse remains the major cause of treatment failure, emphasizing the need for adjuvant immunotherapies. In this regard, post-transplantation dendritic cell (DC) vaccination is a highly interesting strategy to boost graft-versus-tumor responses. Previously, we developed a clinically applicable protocol for simultaneous large-scale generation of end-stage blood DC subsets from donor-derived CD34+ stem cells, including conventional type 1 and 2 DCs (cDC1s and cDC2s), and plasmacytoid DCs (pDCs). In addition, the total cultured end-product (DC-complete vaccine), also contains non-end-stage-DCs (i.e. non-DCs). In this study, we aimed to dissect the phenotypic identity of these non-DCs and their potential immune modulatory functions on the potency of cDCs and pDCs in stimulating tumor-reactive CD8+ T and NK cell responses, in order to obtain rationale for clinical translation of our DC-complete vaccine. The non-DC compartment was heterogeneous and comprised of myeloid progenitors and (immature) granulocyte- and monocyte-like cells. Importantly, non-DCs potentiated toll-like receptor-induced DC maturation, as reflected by increased expression of co-stimulatory molecules and enhanced cDC-derived IL-12 and pDC-derived IFN-α production. Additionally, antigen-specific CD8+ T cells effectively expanded upon DC-complete vaccination in vitro and in vivo. This effect was strongly augmented by non-DCs in an antigen-independent manner. Moreover, non-DCs did not impair in vitro DC-mediated NK cell activation, degranulation nor cytotoxicity. Notably, in vivo i.p. DC-complete vaccination activated i.v. injected NK cells. Together, these data demonstrate that the non-DC compartment potentiates DC-mediated activation and expansion of antigen-specific CD8+ T cells and do not impair NK cell responses in vitro and in vivo. This underscores the rationale for further clinical translation of our CD34+-derived DC-complete vaccine in hemato-oncology patients post alloSCT.

Additional cytogenetic features determine outcome in patients allografted for TP53 mutant acute myeloid leukemia.

BACKGROUND: The presence of TP53 mutations is associated with an unfavorable outcome in patients allografted for acute myeloid leukemia (AML), leading some to question the benefit of an allogeneic stem cell transplantation (allo-SCT) for this patient group, although this has not been studied in a large cohort. METHODS: A total of 780 patients with AML in first complete remission, with either intermediate- or adverse-risk cytogenetics, whose TP53 mutation status was reported, were included in this study from the European Society for Blood and Marrow Transplantation. RESULTS: Two-year overall survival (OS) was impaired in patients (n = 179) with evidence of a TP53 mutation at diagnosis (35.1%; 95% confidence interval [CI], 26.7-43.7) as compared to the cohort without (n = 601) (64%; 95% CI, 59.1-68.4; P = .001). In patients with mutant TP53 AML with no evidence of either chromosome 17p loss (17p-) and/or complex karyotype (CK) (n = 53, 29.6%), 2-year OS was 65.2% (95% CI, 48.4-77.6). This was not significantly different to patients without TP53 mutations. In patients with mutant TP53 AML with either 17p- and/or CK (n = 126, 70.4%), the OS was lower (24.6%; 95% CI, 16.2-34; P = .001). CONCLUSIONS: In summary, the adverse prognostic effect of TP53 mutations in AML following an allo-SCT is not evident in patients with neither co-occurring 17p- and/or CK, and these data inform decisions regarding allo-SCT in patients with TP53 mutant AML.

Safety and efficacy of fedratinib, a selective oral inhibitor of Janus kinase-2 (JAK2), in patients with myelofibrosis and low pretreatment platelet counts.

Fedratinib, an oral Janus kinase-2 (JAK2) inhibitor, is approved for patients with myelofibrosis (MF) and platelet counts ≥50 × 109 /l, based on outcomes from the phase 3, placebo-controlled JAKARTA trial in JAK-inhibitor-naïve MF, and the phase 2, single-arm JAKARTA2 trial in patients previously treated with ruxolitinib. We evaluated the efficacy and safety of fedratinib 400 mg/day in patients with baseline platelet counts 50 to <100 × 109 /l ("Low-Platelets" cohorts), including 14/96 patients (15%) in JAKARTA and 33/97 (34%) in JAKARTA2. At 24 weeks, spleen response rates were not significantly different between the Low-Platelets cohort and patients with baseline platelet counts ≥100 × 109 /l ("High-Platelets" cohort), in JAKARTA (36% vs. 49%, respectively; p = 0.37) or JAKARTA2 (36% vs. 28%; p = 0.41). Symptom response rates were also not statistically different between the Low- and High-Platelets cohorts. Fedratinib was generally well-tolerated in both platelet-count cohorts. New or worsening thrombocytopaenia was more frequent in the Low-Platelets (44%) versus the High-Platelets (9%) cohort, but no serious thrombocytopaenia events occurred. Thrombocytopaenia was typically managed with dose modifications; only 3/48 Low-Platelets patients discontinued fedratinib due to thrombocytopaenia. These data indicate that fedratinib 400 mg/day is safe and effective in patients with MF and low pretreatment platelet counts, and no initial fedratinib dose adjustment is required for these patients.

Clinically applicable CD34+-derived blood dendritic cell subsets exhibit key subset-specific features and potently boost anti-tumor T and NK cell responses.

Allogeneic stem cell transplantation (alloSCT), following induction chemotherapy, can be curative for hemato-oncology patients due to powerful graft-versus-tumor immunity. However, disease recurrence remains the major cause of treatment failure, emphasizing the need for potent adjuvant immunotherapy. In this regard, dendritic cell (DC) vaccination is highly attractive, as DCs are the key orchestrators of innate and adaptive immunity. Natural DC subsets are postulated to be more powerful compared with monocyte-derived DCs, due to their unique functional properties and cross-talk capacity. Yet, obtaining sufficient numbers of natural DCs, particularly type 1 conventional DCs (cDC1s), is challenging due to low frequencies in human blood. We developed a clinically applicable culture protocol using donor-derived G-CSF mobilized CD34+ hematopoietic progenitor cells (HPCs) for simultaneous generation of high numbers of cDC1s, cDC2s and plasmacytoid DCs (pDCs). Transcriptomic analyses demonstrated that these ex vivo-generated DCs highly resemble their in vivo blood counterparts. In more detail, we demonstrated that the CD141+CLEG9A+ cDC1 subset exhibited key features of in vivo cDC1s, reflected by high expression of co-stimulatory molecules and release of IL-12p70 and TNF-α. Furthermore, cDC1s efficiently primed alloreactive T cells, potently cross-presented long-peptides and boosted expansion of minor histocompatibility antigen-experienced T cells. Moreover, they strongly enhanced NK cell activation, degranulation and anti-leukemic reactivity. Together, we developed a robust culture protocol to generate highly functional blood DC subsets for in vivo application as tailored adjuvant immunotherapy to boost innate and adaptive anti-tumor immunity in alloSCT patients.

Allogeneic stem cell transplantation in AML with t(6;9)(p23;q34);DEK-NUP214 shows a favourable outcome when performed in first complete remission.

Acute myeloid leukaemia (AML) with t(6;9)(p23;q34) is a poor-risk entity, commonly associated with FLT3-ITD (internal tandem duplication). Allogeneic stem-cell tranplantation (allo-SCT) is recommended, although studies analysing the outcome of allo-SCT in this setting are lacking. We selected 195 patients with t(6;9) AML, who received a first allo-SCT between 2000 and 2016 from the EBMT (European Society for Blood and Marrow Transplantation) registry. Disease status at time of allo-SCT was the strongest independent prognostic factor, with a two-year leukaemia-free survival and relapse incidence of 57% and 19% in patients in CR1 (first complete remission), 34% and 33% in CR2 (second complete remission), and 24% and 49% in patients not in remission, respectively (P < 0·001). This study, which represents the largest one available in t(6;9) AML, supports the recommendation to submit these patients to allo-SCT in CR1.

Cell composition and expansion strategy can reduce the beneficial effect of AKT-inhibition on functionality of CD8+ T cells.

AKT-inhibition is a promising approach to improve T cell therapies; however, its effect on CD4+ T cells is insufficiently explored. Previously, we and others showed that AKT-inhibition during ex vivo CD8+ T cell expansion facilitates the generation of polyfunctional T cells with stem cell memory-like traits. However, most therapeutic T cell products are generated from lymphocytes, containing CD4+ T cells that can affect CD8+ T cells dependent on the Th-subset. Here, we investigated the effect of AKT-inhibition on CD4+ T cells, during separate as well as total T cell expansions. Interestingly, ex vivo AKT-inhibition preserved the early memory phenotype of CD4+ T cells based on higher CD62L, CXCR4 and CCR7 expression. However, in the presence of AKT-inhibition, Th-differentiation was skewed toward more Th2-associated at the expense of Th1-associated cells. Importantly, the favorable effect of AKT-inhibition on the functionality of CD8+ T cells drastically diminished in the presence of CD4+ T cells. Moreover, also the expansion method influenced the effect of AKT-inhibition on CD8+ T cells. These findings indicate that the effect of AKT-inhibition on CD8+ T cells is dependent on cell composition and expansion strategy, where presence of CD4+ T cells as well as polyclonal stimulation impede the favorable effect of AKT-inhibition.

Decitabine enhances targeting of AML cells by CD34+ progenitor-derived NK cells in NOD/SCID/IL2Rgnull mice.

Combining natural killer (NK) cell adoptive transfer with hypomethylating agents (HMAs) is an attractive therapeutic approach for patients with acute myeloid leukemia (AML). However, data regarding the impact of HMAs on NK cell functionality are mostly derived from in vitro studies with high nonclinical relevant drug concentrations. In the present study, we report a comparative study of azacitidine (AZA) and decitabine (DAC) in combination with allogeneic NK cells generated from CD34+ hematopoietic stem and progenitor cells (HSPC-NK cells) in in vitro and in vivo AML models. In vitro, low-dose HMAs did not impair viability of HSPC-NK cells. Furthermore, low-dose DAC preserved HSPC-NK killing, proliferation, and interferon gamma production capacity, whereas AZA diminished their proliferation and reactivity. Importantly, we showed HMAs and HSPC-NK cells could potently work together to target AML cell lines and patient AML blasts. In vivo, both agents exerted a significant delay in AML progression in NOD/SCID/IL2Rgnull mice, but the persistence of adoptively transferred HSPC-NK cells was not affected. Infused NK cells showed sustained expression of most activating receptors, upregulated NKp44 expression, and remarkable killer cell immunoglobulin-like receptor acquisition. Most importantly, only DAC potentiated HSPC-NK cell anti-leukemic activity in vivo. Besides upregulation of NKG2D- and DNAM-1-activating ligands on AML cells, DAC enhanced messenger RNA expression of inflammatory cytokines, perforin, and TRAIL by HSPC-NK cells. In addition, treatment resulted in increased numbers of HSPC-NK cells in the bone marrow compartment, suggesting that DAC could positively modulate NK cell activity, trafficking, and tumor targeting. These data provide a rationale to explore combination therapy of adoptive HSPC-NK cells and DAC in patients with AML.

Management of myelofibrosis after ruxolitinib failure.

Myelofibrosis is a BCR-ABL1-negative myeloproliferative neoplasm characterized by anemia, progressive splenomegaly, extramedullary hematopoiesis, bone marrow fibrosis, constitutional symptoms, leukemic progression, and shortened survival. Constitutive activation of the Janus kinase/signal transducers and activators of transcription (JAK-STAT) pathway, and other cellular pathways downstream, leads to myeloproliferation, proinflammatory cytokine expression, and bone marrow remodeling. Transplant is the only curative option for myelofibrosis, but high rates of morbidity and mortality limit eligibility. Several prognostic models have been developed to facilitate treatment decisions. Until the recent approval of fedratinib, a JAK2 inhibitor, ruxolitinib was the only available JAK inhibitor for treatment of intermediate- or high-risk myelofibrosis. Ruxolitinib reduces splenomegaly to some degree in almost all treated patients; however, many patients cannot tolerate ruxolitinib due to dose-dependent drug-related cytopenias, and even patients with a good initial response often develop resistance to ruxolitinib after 2-3 years of therapy. Currently, there is no consensus definition of ruxolitinib failure. Until fedratinib approval, strategies to overcome ruxolitinib resistance or intolerance were mainly different approaches to continued ruxolitinib therapy, including dosing modifications and ruxolitinib rechallenge. Fedratinib and two other JAK2 inhibitors in later stages of clinical development, pacritinib and momelotinib, have been shown to induce clinical responses and improve symptoms in patients previously treated with ruxolitinib. Fedratinib induces robust spleen responses, and pacritinib and momelotinib may have preferential activity in patients with severe cytopenias. Reviewed here are strategies to ameliorate ruxolitinib resistance or intolerance, and outcomes of clinical trials in patients with myelofibrosis receiving second-line JAK inhibitors after ruxolitinib treatment.

Fedratinib in patients with myelofibrosis previously treated with ruxolitinib: An updated analysis of the JAKARTA2 study using stringent criteria for ruxolitinib failure.

Fedratinib is an oral, selective Janus kinase 2 (JAK2) inhibitor. The phase II JAKARTA2 study assessed fedratinib in patients with intermediate- or high-risk myelofibrosis (MF) who were resistant or intolerant to prior ruxolitinib per investigator assessment. Patients received fedratinib 400 mg/day in 28-day cycles. The JAKARTA2 outcomes were initially reported using a last-observation-carried forward (LOCF) analysis in a "Per Protocol" population. This updated analysis of JAKARTA2 employs intention-to-treat analysis principles without LOCF for all treated patients (ITT Population; N = 97), and for a patient subgroup who met more stringent definitions of prior ruxolitinib failure (Stringent Criteria Cohort; n = 79). Median duration of prior ruxolitinib exposure was 10.7 months. The primary endpoint was spleen volume response rate (SVRR; ≥35% spleen volume decrease from baseline to end of cycle 6 [EOC6]). The SVRR was 31% in the ITT Population and 30% in the Stringent Criteria Cohort. Median duration of spleen volume response was not reached. Symptom response rate (≥50% reduction from baseline to EOC6 in total symptom score [TSS] on the modified Myelofibrosis Symptom Assessment Form [MFSAF]) was 27%. Grade 3-4 anemia and thrombocytopenia rates were 38% and 22%, respectively. Patients with advanced MF substantially pretreated with ruxolitinib attained robust spleen responses and reduced symptom burden with fedratinib.

Tandem Autologous Stem Cell Transplantation Improves Outcomes in Newly Diagnosed Multiple Myeloma with Extramedullary Disease and High-Risk Cytogenetics: A Study from the Chronic Malignancies Working Party of the European Society for Blood and Marrow Transplantation.

Although high-dose therapy and autologous stem cell transplant combined with novel agents continues to be the hallmark of first-line treatment in newly diagnosed transplant-eligible multiple myeloma patients, the impact of tandem autologous or autologous/reduced-intensity allogeneic transplant for patients with extramedullary disease (EMD) and high-risk cytogenetics is not yet defined. Here, we analyzed clinical and cytogenetic data from 488 adult myeloma patients with EMD undergoing single autologous (n = 373), tandem autologous (n = 84), or autologous-allogeneic transplant (n = 31) between 2003 and 2015. At least 1 high-risk abnormality was present in 41% (n = 202), with del(17p) (40%) and t(4;14) (45%) the most frequent. More than 1 high-risk abnormality was found in 54%. High-risk cytogenetics showed worse 4-year overall survival (OS) and progression-free survival (PFS) of 54% and 29%, respectively, versus 78% and 49% for standard-risk cytogenetics (P < .001). Co-segregation of high-risk abnormalities did not seem to affect outcome. Regarding transplant regimen, OS and PFS were 70% and 43% for single autologous versus 83% and 52% for tandem autologous and 88% and 58% for autologous-allogeneic (P = .06 and P = .30). In multivariate analysis high-risk cytogenetics were associated with worse survival (hazard ratio [HR], 2.00; P = .003), whereas tandem autologous significantly improved outcome versus single autologous transplant (HRs, .46 and .64; P = .02 and P = .03). Autologous-allogeneic transplant did not significantly differ in outcome but appeared to improve survival, but results were limited because of small population (HR, .31). In conclusion, high-risk cytogenetics is frequently observed in newly diagnosed myeloma with EMD and significantly worsens outcome after single autologous, whereas a tandem autologous transplant strategy may overcome onset poor prognosis.

Allogeneic Hematopoietic Cell Transplantation in Patients Aged 50Years or Older with Severe Aplastic Anemia.

We report on 499 patients with severe aplastic anemia aged ≥ 50years who underwent hematopoietic cell transplantation (HCT) from HLA-matched sibling (n = 275, 55%) or HLA-matched (8/8) unrelated donors (n = 187, 37%) between 2005 and 2016. The median age at HCT was 57.8 years; 16% of patients were 65 to 77years old. Multivariable analysis confirmed higher mortality risks for patients with performance score less than 90% (hazard ratio [HR], 1.41; 95% confidence interval [CI], 1.03 to 1.92; P = .03) and after unrelated donor transplantation (HR, 1.47; 95% CI, 1 to 2.16; P = .05). The 3-year probabilities of survival for patients with performance scores of 90 to 100 and less than 90 after HLA-matched sibling transplant were 66% (range, 57% to 75%) and 57% (range, 47% to 76%), respectively. The corresponding probabilities after HLA-matched unrelated donor transplantation were 57% (range, 48% to 67%) and 48% (range, 36% to 59%). Age at transplantation was not associated with survival, but grades II to IV acute graft-versus-host disease (GVHD) risks were higher for patients aged 65years or older (subdistribution HR [sHR], 1.7; 95% confidence interval, 1.07 to 2.72; P = .026). Chronic GVHD was lower with the GVHD prophylaxis regimens calcineurin inhibitor (CNI) + methotrexate (sHR, .52; 95% CI, .33 to .81; P = .004) and CNI alone or with other agents (sHR, .27; 95% CI, .14 to .53; P < .001) compared with CNI + mycophenolate. Although donor availability is modifiable only to a limited extent, choice of GVHD prophylaxis and selection of patients with good performance scores are key for improved outcomes.

Family Mismatched Allogeneic Stem Cell Transplantation for Myelofibrosis: Report from the Chronic Malignancies Working Party of European Society for Blood and Marrow Transplantation.

This analysis included 56 myelofibrosis (MF) patients transplanted from family mismatched donor between 2009 and 2015 enrolled in the European Society for Blood and Marrow Transplantation database. The median age was 57years (range, 38 to 72); 75% had primary MF and 25% had secondary MF. JAK2 V617F was mutated in 61%. Donors were HLA mismatched at 2 or more loci. Stem cells were sourced from bone marrow in 66% and peripheral blood in 34%. The median CD34+ cell dose was 4.8 × 106/kg (range, 1.7 to 22.9; n = 43). Conditioning was predominantly myeloablative in 70% and reduced intensity in the remainder. Regimens were heterogeneous with thiotepa, busulfan, fludarabine, and post-transplant cyclophosphamide used in 59%. The incidence of neutrophil engraftment by 28days was 82% (range, 70% to 93%), at a median of 21days (range, 19 to 23). At 2years the cumulative incidence of primary graft failure was 9% (95% CI 1% to 16%) and secondary graft failure was 13% (95% CI 4% to 22%). The cumulative incidence of acute graft-versus-host disease (GVHD) grades II to IV and III to IV was 28% (95% CI 16% to 40%) and 9% (95% CI 2% to 17%) at 100days. The cumulative incidence of chronic GVHD at 1 year was 45% (95% CI 32% to 58%), but the cumulative incidence of death without chronic GVHD by 1 year was 20% (95% CI 10% to 31%). With a median follow-up of 32 months, the 1- and 2-year overall survival was 61% (95% CI 48% to 74%) and 56% (95% CI 41% to 70%), respectively. The 1- and 2- year progression-free survival was 58% (95% CI 45% to 71%) and 43% (95% CI 28% to 58%), respectively, with a 2-year cumulative incidence of relapse of 19% (95% CI 7% to 31%). The 2-year nonrelapse mortality was 38% (95% CI 24% to 51%). This retrospective study of MF allo-SCT using family mismatched donors demonstrated feasibility of the approach, timely neutrophil engraftment in over 80% of cases, and acceptable overall and progression-free survival rates with relapse rates not dissimilar to the unrelated donor setting. However, strategies to minimize the risk of graft failure and the relatively high nonrelapse mortality need to be used, ideally in a multicenter prospective fashion.

Allogeneic Stem Cell Transplantation for Blast Crisis Chronic Myeloid Leukemia in the Era of Tyrosine Kinase Inhibitors: A Retrospective Study by the EBMT Chronic Malignancies Working Party.

The prognosis of patients with blast crisis (BC) chronic myeloid leukemia (CML) is still dismal. Allogeneic stem cell transplantation represents the only curative treatment option, but data on transplant outcomes are scarce. We therefore conducted a retrospective, registry-based study of adult patients allografted for BC CML, focusing on patients with active disease at transplant and pretransplant prognostic factors. One hundred seventy patients allografted for BC CML after tyrosine kinase inhibitor pretreatment between 2004 and 2016 were analyzed. Before transplant, 95 patients were in remission, whereas 75 patients had active BC. In multivariable analysis of the entire cohort, active BC at transplant was the strongest factor associated with decreased overall survival (hazrd ratio, 1.87; P = .010) and shorter leukemia-free survival (LFS; hazard ratio, 1.69; P = .017). For patients with BC in remission at transplant, advanced age (≥45 years), lower performance status (≤80%), longer interval from diagnosis BC to transplant (>12 months), myeloablative conditioning, and unrelated donor (UD) transplant were risk factors for inferior survival. In patients with active BC, only UD transplant was significantly associated with prolonged LFS and trended toward improved overall survival. In summary, survival of patients allografted for BC CML was strongly dependent on pretransplant remission status. In patients with remission of BC, conventional prognostic factors remained the major determinants of outcome, whereas in those with active BC at transplant, UD transplant was associated with prolonged LFS in our study.

Phase I/II Trial of a Combination of Anti-CD3/CD7 Immunotoxins for Steroid-Refractory Acute Graft-versus-Host Disease.

Effective therapies for treating patients with steroid-refractory acute graft-versus-host-disease (SR-aGVHD), particularly strategies that reduce the duration of immunosuppression following remission, are urgently needed. The investigated immunotoxin combination consists of a mixture of anti-CD3 and anti-CD7 antibodies separately conjugated to recombinant ricin A (CD3/CD7-IT), which induces in vivo depletion of T cells and natural killer (NK) cells and suppresses T cell receptor activation. We conducted a phase I/II trial to examine the safety and efficacy of CD3/CD7-IT in 20 patients with SR-aGVHD; 17 of these patients (85%) had severe SR-aGVHD, and all 20 patients had visceral organ involvement, including 18 (90%) with gastrointestinal (GI) involvement and 5 (25%) with liver involvement. A validated 2-biomarker algorithm classified the majority of patients (11 of 20) as high risk. On day 28 after the start of CD3/CD7-IT therapy, the overall response rate was 60% (12 of 20), with 10 patients (50%) achieving a complete response. The 6-month overall survival rate was 60% (12 of 20), including 64% (7 of 11) classified as high risk by biomarkers. The 1-week course of treatment with CD3/CD7-IT caused profound but transient depletion of T cells and NK cells, followed by rapid recovery of the immune system with a diverse TCR Vß repertoire, and preservation of Epstein-Barr virus- and cytomegalovirus-specific T cell clones. Furthermore, our results indicate that CD3/CD7-IT appeared to be safe and well tolerated, with a relatively low prevalence of manageable and reversible adverse events, primarily worsening of hypoalbuminemia, microangiopathy, and thrombocytopenia. These encouraging results suggest that CD3/CD7-IT may improve patient outcomes in patients with SR-aGVHD.

Allograft and patient survival after sequential HSCT and kidney transplantation from the same donor-A multicenter analysis.

Tolerance induction through simultaneous hematopoietic stem cell and renal transplantation has shown promising results, but it is hampered by the toxicity of preconditioning therapies and graft-versus-host disease (GVHD). Moreover, renal function has never been compared to conventionally transplanted patients, thus, whether donor-specific tolerance results in improved outcomes remains unanswered. We collected follow-up data of published cases of renal transplantations after hematopoietic stem cell transplantation from the same donor and compared patient and transplant kidney survival as well as function with caliper-matched living-donor renal transplantations from the Austrian dialysis and transplant registry. Overall, 22 tolerant and 20 control patients were included (median observation period 10 years [range 11 months to 26 years]). In the tolerant group, no renal allograft loss was reported, whereas 3 were lost in the control group. Median creatinine levels were 85 µmol/l (interquartile range [IQR] 72-99) in the tolerant cohort and 118 µmol/l (IQR 99-143) in the control group. Mixed linear-model showed around 29% lower average creatinine levels throughout follow-up in the tolerant group (P < .01). Our data clearly show stable renal graft function without long-term immunosuppression for many years, suggesting permanent donor-specific tolerance. Thus sequential transplantation might be an alternative approach for future studies targeting tolerance induction in renal allograft recipients.

Prophylactic donor lymphocyte infusion after allogeneic stem cell transplantation in acute leukaemia - a matched pair analysis by the Acute Leukaemia Working Party of EBMT.

Strategies for relapse prevention after allogeneic transplantation in acute leukaemia are warranted. A registry-based matched-pair analysis evaluated the efficacy of prophylactic donor lymphocyte infusion (proDLI). Adults receiving proDLI in complete remission (CR) and controls were pair-matched for age, diagnosis, cytogenetics, stage, donor, gender, conditioning and T-cell depletion. Eighty-nine pairs were identified (median follow-up: 6.9 years). Within the entire cohort, no difference was observed. However, among patients with high-risk acute myeloid leukaemia (AML) (unfavourable cytogenetics and/or transplanted beyond first CR), proDLI recipients had improved overall survival (69.8% vs. 40.2% in controls, P = 0.027). ProDLI has moderate efficacy, but can contribute to improved outcome in high-risk AML.

Increased Coexpression of PD-1, TIGIT, and KLRG-1 on Tumor-Reactive CD8+ T Cells During Relapse after Allogeneic Stem Cell Transplantation.

Allogeneic stem cell transplantation (allo-SCT) can be a curative treatment for patients with a hematologic malignancy due to alloreactive T cell responses recognizing minor histocompatibility antigens (MiHA). Yet tumor immune escape mechanisms can cause failure of T cell immunity, leading to relapse. Tumor cells display low expression of costimulatory molecules and can up-regulate coinhibitory molecules that inhibit T cell functionality on ligation with their counter-receptors on the tumor-reactive T cells. The aim of this explorative study was to evaluate immune checkpoint expression profiles on T cell subsets and on cytomegalovirus (CMV)- and/or MiHA-reactive CD8+ T cells of allo-SCT recipients using a 13-color flow cytometry panel, and to correlate these expression patterns to clinical outcomes. MiHA-reactive CD8+ T cells exhibited an early differentiated CD27++/CD28++ phenotype with low KLRG-1 and CD57 expression. These T cells also displayed increased expression of PD-1, TIM-3, and TIGIT compared with total effector memory T cells and CMV-specific CD8+ T cells in healthy donors and allo-SCT recipients. Remarkably, high coexpression of PD-1, TIGIT, and KLRG-1 on MiHA-reactive CD8+ T cells was associated with relapse after allo-SCT. Taken together, these findings indicate that MiHA-specific CD8+ T cells of relapsed patients have a distinctive coinhibitory expression signature compared with patients who stay in remission. This phenotype may serve as a potential monitoring tool in patients. Moreover, these findings suggest that PD-1 and TIGIT play important roles in regulating T cell-mediated tumor control, providing a rationale for immunotherapy with blocking antibodies to treat relapse after allo-SCT.