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.

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.

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.

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.

Immune checkpoint molecules in acute myeloid leukaemia: managing the double-edged sword.

New immunotherapeutic interventions have revolutionized cancer treatment. The immune responsiveness of acute myeloid leukaemia (AML) was first demonstrated by allogeneic stem cell transplantation. In addition, milder immunotherapeutic approaches are exploited. However, the long-term efficacy of these therapies is hampered by various immune resistance and editing mechanisms. In this regard, co-inhibitory signalling pathways have been shown to play a crucial role. Via up-regulation of inhibitory checkpoints, tumour-reactive T cell and Natural Killer cell responses can be strongly impeded. Accordingly, the introduction of checkpoint inhibitors targeting CTLA-4 (CTLA4) and PD-1 (PDCD1, CD279)/PD-L1 (CD274, PDCD1LG1) accomplished a breakthrough in cancer treatment, with impressive clinical responses. Numerous new co-inhibitory players and novel combination therapies are currently investigated for their potential to boost anti-tumour immunity and improve survival of cancer patients. Although the challenge here remains to avoid severe systemic toxicity. This review addresses the involvement of co-inhibitory signalling in AML immune evasion and discusses the opportunities for checkpoint blockers in AML treatment.

Combination Therapy with Inolimomab and Etanercept for Severe Steroid-Refractory Acute Graft-versus-Host Disease.

Steroid-refractory acute graft-versus-host disease (aGVHD) remains an important cause of morbidity and mortality after allogeneic stem cell transplantation (SCT). A protocol on the management of aGVHD was introduced in our center that incorporated a prospective study on combination therapy with inolimomab (anti-IL-2Rα) and etanercept (anti-tumor necrosis factor-α) for steroid-refractory aGVHD. We evaluated the efficacy and safety in 21 consecutively treated patients. The patients had developed refractory aGVHD after SCT (n = 16) or donor lymphocyte infusion (n = 5), and aGVHD was classified as severe in all patients, mostly due to gastrointestinal involvement stages 2 to 4. No drug-related side effects were observed apart from the infections expected to occur in these severely immunocompromised patients. Overall response at day 28 of second-line therapy was 48% (10/21), with 6 and 4 patients achieving a complete and partial response, respectively. Eventually, 19 patients died (90%), with early mortality (<6 months) predominantly resulting from refractory aGVHD and secondary infections and late mortality resulting from relapse of the underlying disease. With a median follow-up of 55 days, the estimated rates of 6-month and 2-year overall survival were dismal, 29% and 10%, respectively. In conclusion, the combination of inolimomab and etanercept for steroid-refractory aGVHD failed to improve the dismal prognosis of severe steroid-refractory aGVHD.

Addition of 10-Day Decitabine to Fludarabine/Total Body Irradiation Conditioning is Feasible and Induces Tumor-Associated Antigen-Specific T Cell Responses.

Allogeneic hematopoietic cell transplantation (HCT) offers the possibility of curative therapy for patients with myelodysplastic syndromes (MDS), chronic myelomonocytic leukemia (CMML), and acute myelogenous leukemia (AML). However, post-HCT relapse remains a major problem, particularly in patients with high-risk cytogenetics and in patients who cannot tolerate consolidation chemotherapy (eg, due to previous toxicity). We assessed the toxicity and efficacy of 10-day decitabine (Dec), fludarabine (Flu), and 2 Gy total body irradiation (TBI) as a new conditioning regimen for allogeneic HCT in patients with MDS, CMML, or AML. Thirty patients were enrolled, including 11 with MDS, 2 with CMML, and 17 with AML. Patients received 20 mg/m(2)/day Dec on days -11 to -2, 30 mg/m(2)/day Flu on days -4 to -2, and 2 Gy TBI on day -1, followed by infusion of a donor stem cell graft on day 0. Postgrafting immunosuppression consisted of cyclosporin A and mycophenolate mofetil. At a median follow-up of 443 days, the overall survival was 53%, relapse incidence was 27%, and nonrelapse mortality was 27%. The incidence of severe acute (grade III/IV) graft-versus-host disease (GVHD) was 27%, and that of (predominantly mild) chronic GVHD was 60%. Immunomonitoring studies revealed that specific CD8(+) T cell responses against epigenetically silenced tumor-associated antigens (TAAs), including cancer-testis antigens (MAGE-A1/A2/A3 and PRAME) and RHAMM, occurred more frequently in patients who had received Dec/Flu/TBI conditioning (8 of 11 patients) compared with a control group of patients who had received only Flu/TBI conditioning (2 of 9 patients). In summary, Dec/Flu/TBI conditioning proved feasible and effective and enhanced the induction of TAA-reactive CD8(+) T cell responses in vivo, which may contribute to disease control post-transplantation.

Thiotepa-based versus total body irradiation-based myeloablative conditioning prior to allogeneic stem cell transplantation for acute myeloid leukaemia in first complete remission: a retrospective analysis from the Acute Leukemia Working Party of the European Group for Blood and Marrow Transplantation.

Thiotepa is an alkylating compound with an antineoplastic and myeloablative activity and can mimic the effect of radiation. However, it is unknown whether this new regimen could safely replace the long-established ones. This retrospective matched-pair analysis evaluated the outcome of adults with acute myeloid leukaemia in first complete remission who received myeloablative conditioning either with a thiotepa-based (n = 121) or a cyclophosphamide/total body irradiation-based (TBI; n = 358) regimen for allogeneic hematopoietic stem cell transplantation from an HLA-matched sibling or an unrelated donor. With a median follow-up of 44 months, the outcome was similar in both groups. Acute graft-versus-host disease grade II-IV was observed in 25% after thiotepa-containing regimen versus 35% after TBI (P = 0.06). The 2-yr cumulative incidence of chronic graft-versus-host disease was 40.5% for thiotepa and 41% for TBI (P = 0.98). At 2 yrs, the cumulative incidences of non-relapse mortality and relapse incidence were 23.9% (thiotepa) vs. 22.4% (TBI; P = 0.66) and 17.2% (thiotepa) vs. 23.3% (TBI; P = 0.77), respectively. The probabilities of leukaemia-free and overall survival at 2 yrs were not significantly different between the thiotepa and TBI groups, at 58.9% vs. 54.2% (P = 0.95) and 61.4% vs. 58% (P = 0.72), respectively. Myeloablative regimens using combinations including thiotepa can provide satisfactory outcomes, but the optimal conditioning remains unclear for the individual patient in this setting.

Human secondary lymphoid organs typically contain polyclonally-activated proliferating regulatory T cells.

Immunomodulating regulatory T-cell (Treg) therapy is a promising strategy in autoimmunity and transplantation. However, to achieve full clinical efficacy, better understanding of in vivo human Treg biology is warranted. Here, we demonstrate that in contrast to blood and bone marrow Tregs, which showed a resting phenotype, the majority of CD4(pos)CD25(pos)CD127(neg)FoxP3(pos) Tregs in secondary lymphoid organs were proliferating activated CD69(pos)CD45RA(neg) cells with a hyperdemethylated FOXP3 gene and a broad T-cell receptor-Vß repertoire, implying polyclonal activation. Activated CD69(pos) Tregs were distributed over both T-cell and B-cell areas, distant from Aire(pos) and CD11c(pos) cells. In contrast to the anergic peripheral blood Tregs, lymphoid organ Tregs had significant ex vivo proliferative capacity and produced cytokines like interleukin-2, while revealing similar suppressive potential. Also, next to Treg-expressing chemokine receptors important for a prolonged stay in lymphoid organs, a significant part of the cells expressed peripheral tissue-associated, functional homing markers. In conclusion, our data suggest that human secondary lymphoid organs aid in the maintenance and regulation of Treg function and homeostasis. This knowledge may be exploited for further optimization of Treg immunotherapy, for example, by ex vivo selection of Tregs with capacity to migrate to lymphoid organs providing an in vivo platform for further Treg expansion.

Early administration of donor lymphocyte infusions upon molecular relapse after allogeneic hematopoietic stem cell transplantation for chronic myeloid leukemia: a study by the Chronic Malignancies Working Party of the EBMT.

Patients with chronic myeloid leukemia relapsing after allogeneic hematopoietic stem cell transplantation may be treated by tyrosine kinase inhibitors and/or by donor lymphocyte infusions. The best strategies and timing of administration of lymphocytes are unclear. We analyzed 155 patients who relapsed after allogeneic stem cell transplantation with disease detectable only by molecular methods and who subsequently received lymphocytes. Transplants were performed in first chronic phase (n=125) or in advanced disease (n=29) from identical siblings (n=84) or unrelated donors (n=71) between 1986 and 2003. They received lymphocytes either during molecular relapse (n=85) or upon progression to more advanced disease (1993 to 2004). The median interval from relapse to lymphocyte infusion was 210 (0-1673) days. The median follow up after it was 46 (3-135) months. Overall survival was 76±4% at five years after lymphocyte infusions (89±8% with sibling donors and 63±13% with unrelated donors (P=0.003)). Survival was 69±14% when lymphocytes were given within six months of the detection of molecular relapse and 81±10% (P=0.061) when given later; 81±11% if given at molecular relapse versus 71±12% (P=0.26) with more advanced disease. In multivariate analysis survival was worse if the donor was unrelated (HR 2.54 (95% CI: 1.15-5.53), P=0.021) and better with lymphocyte infusions beyond six months from molecular relapse (HR 0.4 (95%CI: 0.19-0.84), P=0.018). These data confirm the remarkable efficacy of lymphocyte infusions for this disease. There appears to be no advantage from administering it early upon detection of molecular relapse in patients who received allogeneic stem cell transplantation for chronic myeloid leukemia.

Endothelial Activation and Stress Index (EASIX) to predict mortality after allogeneic stem cell transplantation: a prospective study.

BACKGROUND: We previously reported that the "Endothelial Activation and Stress Index" (EASIX; ((creatinine×lactate dehydrogenase)÷thrombocytes)) measured before start of conditioning predicts mortality after allogeneic hematopoietic stem cell transplantation (alloSCT) when used as continuous score. For broad clinical implementation, a prospectively validated EASIX-pre cut-off is needed that defines a high-risk cohort and is easy to use. METHOD: In the current study, we first performed a retrospective cohort analysis in n=2022 alloSCT recipients and identified an optimal cut-off for predicting non-relapse mortality (NRM) as EASIX-pre=3. For cut-off validation, we conducted a multicenter prospective study with inclusion of n=317 first alloSCTs from peripheral blood stem cell in adult patients with acute leukemia, lymphoma or myelodysplastic syndrome/myeloproliferative neoplasms in the European Society for Blood and Marrow Transplantation network. RESULTS: Twenty-three % (n=74) of alloSCT recipients had EASIX-pre ≥3 taken before conditioning. NRM at 2 years was 31.1% in the high EASIX group versus 11.5% in the low EASIX group (p<0.001). Patients with high EASIX-pre also had worse 2 years overall survival (51.6% vs 70.9%; p=0.002). We were able to validate the cut-off and found that EASIX ≥3 was associated with more than twofold increased risk for NRM in multivariate analysis (HR=2.18, 95% CI 1.2 to 3.94; p=0.01). No statistically significant difference could be observed for the incidence of relapse. CONCLUSIONS: The results of this study provide a prospectively validated standard laboratory biomarker index to estimate the transplant-related mortality risk after alloSCT. EASIX ≥3 taken before conditioning identifies a population of alloSCT recipients who have a more than twofold increased risk of treatment-related mortality.

Allogeneic Stem Cell Transplantation in Patients >40 Years of Age With Acute Lymphoblastic Leukemia: Reduced Intensity Versus Myeloablative Conditioning.

BACKGROUND: The outcome in older patients with acute lymphoblastic leukemia (ALL) remains unsatisfactory due to high relapse and nonrelapse mortality (NRM) rates. Allogeneic stem cell transplantation (alloHSCT) as postremission therapy has an important role in reducing relapse rate, albeit its application is limited in older adult patients due to alloHSCT-related morbidity and mortality. Reduced-intensity conditioning (RIC) alloHSCT has been developed as a less toxic conditioning regimen, but comparative studies with myeloablative conditioning (MAC) are limited in patients with ALL. METHODS: In this retrospective study, RIC-alloHSCT (n = 111) was compared with MAC-alloHSCT (n = 77) in patients aged 41 to 65 y with ALL in first complete remission. MAC was predominantly applied by combining high-dose total body irradiation and cyclophosphamide, whereas RIC mainly consisted of fludarabine and 2 Gy total body irradiation. RESULTS: Unadjusted overall survival was 54% (95% confidence interval [CI], 42%-65%) at 5 y in MAC recipients compared with 39% (95% CI, 29%-49%) in RIC recipients. Overall survival and relapse-free survival were not significantly associated with type of conditioning after adjusted for the covariates age, leukemia risk status at diagnosis, donor type, and donor and recipient gender combination. NRM was significantly lower after RIC (subdistribution hazard ratio: 0.41, 95% CI, 0.22-0.78; P = 0.006), whereas relapse was significantly higher (subdistribution hazard ratio: 3.04, 95% CI, 1.71-5.40; P < 0.001). CONCLUSIONS: Collectively, RIC-alloHSCT has resulted in less NRM, but it was also found to be associated with a significantly higher relapse rate. These results suggest that MAC-alloHSCT may provide a more effective type of consolidation therapy for the reduction of relapse and that RIC-alloHSCT may be restricted to patients at higher risk for NRM.

Invasive Fungal Disease in Patients with Myeloid Malignancies: A Retrospective Cohort Study of a Diagnostic-Driven Care Pathway Withholding Mould-Active Prophylaxis.

OBJECTIVES: Patients receiving remission induction therapy for acute myeloid leukaemia (AML) are at high risk of developing invasive fungal disease (IFD). Newer therapies with targeted antileukemic agents and the emergence of azole resistance pose a challenge to the strategy of primary antifungal prophylaxis. We report the experience of a diagnostic-driven care pathway (DCP) for the management of IFD in these patients, using only culture-directed mould inactive prophylaxis. METHODS: Retrospectively, we used a single-centre study of consecutive patients receiving intensive chemotherapy for myeloid malignancies between 2014 and 2021. DCP consisted of serial cultures and serum galactomannan (sGM) screening, CT imaging, and bronchoscopy to direct targeted antifungal treatment. IFD was classified according to the 2020 EORTC/MSGERC criteria. RESULTS: A total of 192 patients with myeloid malignancies received 300 courses of intensive chemotherapy. There were 14 cases of invasive yeast infections and 18 of probable/proven invasive mould disease (IMD). The incidence of probable/proven IMD during the first cycle of remission-induction chemotherapy was 4.6% (n = 9). sGM remained negative in all cases of invasive aspergillosis (IA), with positive mycology findings in bronchoalveolar lavage. All-cause mortality was 9.4% (n = 18) 100 days after starting chemotherapy and was comparable between patients with or without IFD. The fungal-related mortality was 1% (n = 2). CONCLUSION: Diagnostic-driven based management without universal mould active prophylaxis is a feasible strategy in the management of IFD and limits unnecessary antimould treatment during intensive chemotherapy. The poor performance of serial serum galactomannan screening in detecting IA warrants further investigation.

Polymorphisms in CCR6 are associated with chronic graft-versus-host disease and invasive fungal disease in matched-related hematopoietic stem cell transplantation.

Graft-versus-host disease (GVHD) and fungal infections are frequent complications after allogeneic hematopoietic stem cell transplantation (HSCT). Single nucleotide polymorphisms (SNPs) in genes of the immune system can influence the inflammatory cascade and T cell-driven alloimmune reactions after HSCT, and thus increasing the incidence of GVHD and infectious complications. Here, we investigated the effect of SNPs in IL-23R and CCR6 on posttransplantation outcome in 161 recipients of partially T cell-depleted HSCT. Remarkably, IL-23R SNPs were not associated with clinical outcome, but we found that disparities in the CCR6 tagSNP rs2301436 and SNP rs3093023 are independently associated with the occurrence of chronic GVHD (cGVHD) and invasive fungal disease. In multivariate analysis, patients receiving a transplant from a homozygous rs2301436 G allele donor showed less cGVHD (odds ratio [OR]: 0.16; P = .002), as was the case for a homozygous donor rs3093023 G allele (OR: 0.24; P = .005). In parallel, the GG genotype at rs2301436 in donors was associated with a higher incidence of invasive fungal disease at day 100 after HSCT (OR: 3.59; P = .008). This study shows that CCR6 SNPs can be used to predict clinical outcome, and that polymorphisms in the CCR6 gene may influence T cell-mediated immune reactions after HSCT.

Low relapse risk in poor risk AML after conditioning with 10-day decitabine, fludarabine and 2 Gray TBI prior to allogeneic hematopoietic cell transplantation.

Patients with poor risk acute myeloid leukemia (AML) have a dismal outcome. We hypothesized that combining decitabine with a standard non-myeloablative (NMA) conditioning regimen prior to allogeneic hematopoietic cell transplantation (allo HCT), might decrease the relapse incidence. We conducted a multicenter prospective phase II study (NCT02252107) with 10-day decitabine (20 mg/m2/day) integrated in a standard non-myeloablative conditioning regimen (3 days fludarabine 30 mg/m2 with 2 Gray total body irradiation (TBI)). Patients with AML ≥ 18 years in 1st (in)complete remission (CR/CRi) with a poor or very poor risk profile, as defined by the HOVON-132 protocol, were eligible. Results: Forty-six patients (median age 60; range 23-74) were included. Median follow up time was 44 months (range 31-65 months). The cumulative 1-year incidence of relapse and NRM were respectively 23% and 11%. Incidence of grade III-IV acute graft-vs-host-disease (GVHD) and severe chronic GVHD were 13% and 20%, respectively. One-year OS was 70%. Application of ELN 2017 risk classification to the study cohort revealed a cumulative one-year relapse rate of respectively 31% and 13% for the adverse and intermediate risk patients. To conclude, the 10-day DEC/FLU/TBI conditioning regimen prior to allo HCT in poor risk AML patients is effective and feasible.

CD34+ progenitor-derived NK cell and gemcitabine combination therapy increases killing of ovarian cancer cells in NOD/SCID/IL2Rgnull mice.

Combining natural killer (NK) cell adoptive transfer with tumor-sensitizing chemotherapy is an attractive approach against recurrent ovarian cancer (OC), as OC is sensitive to NK cell-mediated immunity. Previously, we showed that CD34+ hematopoietic progenitor cell (HPC)-derived NK cells can kill OC cells in vitro and inhibit OC tumor growth in mice. Here, we investigated the potential of HPC-NK cell therapy combined with chemotherapeutic gemcitabine (used in recurrent OC patients) against OC. We examined the phenotypical, functional, and cytotoxic effects of gemcitabine on HPC-NK cells and/or OC cells in vitro and in OC-bearing mice. To this end, we treated OC cells and/or HPC-NK cells with or without gemcitabine and analyzed the phenotype, cytokine production, and anti-tumor reactivity. We found that gemcitabine did not affect the phenotype and functionality of HPC-NK cells, while on OC cells expression of NK cell activating ligands and death receptors was upregulated. Although gemcitabine pre-treatment of OC cells did not improve the functionality of HPC-NK cells, importantly, HPC-NK cells and gemcitabine additively killed OC cells in vitro. Similarly, combined HPC-NK cell and gemcitabine treatment additively decreased tumor growth in OC-bearing mice. Collectively, our results indicate that combination therapy of HPC-NK cells and gemcitabine results in augmented OC killing in vitro and in vivo. This provides a rationale for exploring this therapeutic strategy in patients with recurrent OC.

Underdiagnosed veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) as a major cause of multi-organ failure in acute leukemia transplant patients: an analysis from the EBMT Acute Leukemia Working Party.

Allogeneic hematopoietic cell transplantation (alloHCT) is a complex, potentially fatal therapy featuring a myriad of complications. Triggering event(s) of such complications vary significantly, but often a so-called "multi-organ failure" (MOF) is reported as the leading cause of death. The identification of the exact trigger of MOF is critical towards early and disease-specific intervention to improve outcome. We examined data from 202 alloHCT patients reported to have died of MOF from the EBMT registry aiming to determine their exact cause of death focusing on veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) due to its life-threatening, often difficult to capture yet preventable nature. We identified a total of 70 patients (35%) for whom VOD/SOS could be considered as trigger for MOF and leading cause of death, among which 48 (69%) were previously undiagnosed. Multivariate analysis highlighted history of hepatic comorbidity or gentuzumab use and disease status beyond CR1 as the only significant factors predictive of VOD/SOS incidence (OR = 6.6; p = 0.001 and OR = 3.3; p = 0.004 respectively). VOD/SOS-related MOF was widely under-reported, accounting for 27% of deaths attributed to MOF of unknown origin without a previous VOD/SOS diagnosis. Our results suggest most missed cases developed late VOD/SOS beyond 21 days post-alloHCT, highlighting the importance of the newly revised EBMT criteria.