The use of ATG abrogates the antileukemic effect of cytomegalovirus reactivation in patients with acute myeloid leukemia receiving grafts from unrelated donors

Memory T-cell enriched haploidentical transplantation with NK cell addback results in promising long-term outcomes: a phase II trial

BACKGROUND

Relapse remains a challenge after transplantation in pediatric patients with hematological malignancies. Myeloablative regimens used for disease control are associated with acute and long-term adverse effects. We used a CD45RA-depleted haploidentical graft for adoptive transfer of memory T cells combined with NK-cell addback and hypothesized that maximizing the graft-versus-leukemia (GVL) effect might allow for reduction in intensity of conditioning regimen.

METHODS

In this phase II clinical trial (NCT01807611), 72 patients with hematological malignancies (complete remission (CR)1: 25, ≥ CR2: 28, refractory disease: 19) received haploidentical CD34 + enriched and CD45RA-depleted hematopoietic progenitor cell grafts followed by NK-cell infusion. Conditioning included fludarabine, thiotepa, melphalan, cyclophosphamide, total lymphoid irradiation, and graft-versus-host disease (GVHD) prophylaxis consisted of a short-course sirolimus or mycophenolate mofetil without serotherapy.

RESULTS

The 3-year overall survival (OS) and event-free-survival (EFS) for patients in CR1 were 92% (95% CI:72-98) and 88% (95% CI: 67-96); ≥ CR2 were 81% (95% CI: 61-92) and 68% (95% CI: 47-82) and refractory disease were 32% (95% CI: 11-54) and 20% (95% CI: 6-40). The 3-year EFS for all patients in morphological CR was 77% (95% CI: 64-87) with no difference amongst recipients with or without minimal residual disease (P = 0.2992). Immune reconstitution was rapid, with mean CD3 and CD4 T-cell counts of 410/μL and 140/μL at day + 30. Cumulative incidence of acute GVHD and chronic GVHD was 36% and 26% but most patients with acute GVHD recovered rapidly with therapy. Lower rates of grade III-IV acute GVHD were observed with NK-cell alloreactive donors (P = 0.004), and higher rates of moderate/severe chronic GVHD occurred with maternal donors (P = 0.035).

CONCLUSION

The combination of a CD45RA-depleted graft and NK-cell addback led to robust immune reconstitution maximizing the GVL effect and allowed for use of a submyeloablative, TBI-free conditioning regimen that was associated with excellent EFS resulting in promising long-term outcomes in this high-risk population. The trial is registered at ClinicalTrials.gov (NCT01807611).

Prognostic factors and impact of CMV reactivation on acute myeloid leukemia patients after HLA-matched myeloablative allogeneic stem cell transplantation in a high CMV prevalence country

INTRODUCTION

Relapse of acute myeloid leukemia (AML) after allogeneic stem cell transplantation (allo-SCT) leads to dismal outcomes. This study aimed to identify high-risk patients and explore the effects of cytomegalovirus (CMV) reactivation in a high CMV-seropositive population.

METHODS

The study involved a single-center retrospective cohort in Thailand, analyzing clinical risk factors and CMV-mediated immune responses, correlated with transplant outcomes in AML patients.

RESULTS

Eighty-five patients with AML in complete remission (CR) undergoing HLA-matched myeloablative allo-SCT between 2011 and February 2021 were enrolled. The relapse rate was 27.1% with the median time of 7 months after transplantation. The 3-year relapse-free-survival (RFS) and overall-survival (OS) were 72.2% and 80.8%, respectively. The disease status (>CR1) and absence of chronic graft-versus-host disease (cGVHD) were independently significant adverse prognostic factors of RFS and OS. Ninety-two percent of recipient-donor pairs were both CMV seropositive. The CMV reactivation occurred in 54.1% of the patients. The clinically significant CMV infection rate was 49.4%. No CMV syndrome/disease or CMV-related mortality occurred. One-year cumulative incidence of relapse among CMV-reactivation and non-reactivation groups were 14.3% and 25.6%, respectively, without a statistically significant difference. Transplantation-related mortality was 11.1%.

CONCLUSIONS

The transplantation beyond CR1 and absence of cGVHD are powerful prognostic factors associated with inferior RFS and OS. In a high CMV prevalence country, there appears to be no impact of CMV reactivation on relapse in AML patients undergoing an allo-SCT.

Impact of CMV reactivation on relapse of acute myeloid leukemia after HCT is dependent on disease stage and ATG

The impact of CMV reactivation on hematologic relapse after HCT is modulated by AML stage (CR1 or advanced) and in vivo T cell depletion.

Following CMV reactivation, NRM was increased in CR1 patients without ATG, but not in patients with ATG or advanced disease stages.

Cytomegalovirus (CMV) reactivation is a frequent complication after allogeneic hematopoietic cell transplantation (HCT), whose impact on clinical outcome, in particular on leukemic relapse, is controversial. We retrospectively analyzed 687 HCT recipients with acute myeloid leukemia (AML) and ciclosporin-based immunosuppression to better understand the differential impact of CMV on transplant outcomes depending on AML disease stage and in vivo T cell depletion with antithymocyte globulin (ATG). Without ATG, CMV reactivation associated with significantly reduced relapse, yet its effect was more pronounced for advanced disease AML (P = .0002) than for patients in first complete remission (CR1, P = .0169). Depending on the disease stage, ATG exposure abrogated relapse protection following CMV reactivation in advanced stages (P = .796), while it inverted its effect into increased relapse for CR1 patients (P = .0428). CMV reactivation was associated with significantly increased nonrelapse mortality in CR1 patients without ATG (P = .0187) but not in those with advanced disease and ATG. Following CMV reactivation, only patients with advanced disease had significantly higher event-free survival rates as compared with patients without CMV. Overall, our data suggest that both ATG and disease stage modulate the impact of post-HCT CMV reactivation in opposite directions, revealing a level of complexity that warrants future studies regarding the interplay between antivirus and antitumor immunity.

Ruxolitinib early administration reduces acute GVHD after alternative donor hematopoietic stem cell transplantation in acute leukemia

This study aimed to observe the safety and clinical efficacy of early application of ruxolitinib to prevent acute graft-versus-host disease (aGVHD) after alternative donor transplantation in acute leukemia. There were 57 patients undergoing allo-HSCT at the Affiliated Cancer Hospital of Zhengzhou University from July 2017 to October 2019. They were divided into control(16 patients) and ruxolitinib (41 patients) groups. For aGVHD prophylaxis, the control group received post-transplantation cyclophosphamide, antithymocyte globulin-Fresenius, cyclosporine A, and mycophenolate mofetil, while in the ruxolitinib group, ruxolitinib 5 mg/d in adults or 0.07–0.1 mg/(kg d) in children was administered from the day of neutrophil engraftment to 100 days post-transplantation based on control group. We found 55 patients had successful reconstitution of hematopoiesis; No significant difference was found in cGVHD, hemorrhagic cystitis, pulmonary infection, intestinal infection, Epstein-Barr virus infection, cytomegalovirus infection, relapse, death, and nonrelapse mortality. The incidences of aGVHD (50 vs. 22%, P = 0.046) and grade II–IV aGVHD (42.9 vs. 12.2%, P = 0.013) were significantly higher in the control group than in the ruxolitinib group. No significant differences were observed in overall survival (P = 0.514), disease-free survival (P = 0.691), and cumulative platelet transfusion within 100 days post-transplantation between two groups. This suggests early application of ruxolitinib can reduce the incidence and severity of aGVHD and patients are well tolerated.

Cytomegalovirus kinetics after hematopoietic cell transplantation reveal peak titers with differential impact on mortality, relapse and immune reconstitution

Even in the era of PCR-based monitoring, prophylaxis, and preemptive therapy, Cytomegalovirus (CMV) viremia remains a relevant cause of non-relapse mortality (NRM) after allogeneic hematopoietic cell transplantation (HCT). However, studies using binary analysis (presence/absence of CMV) reported contradicting data for NRM, overall survival and leukemia relapse. Here, we analyzed CMV replication kinetics in 11 508 whole blood PCR samples of 705 patients with HCT between 2012 and 2017. Using two independent models based on CMV peak titers and on the time point of first CMV reactivation, we stratified patients into risk cohorts. Each cohort had distinct cellular immune reconstitution profiles and differentiated for relevant clinical outcomes. Patients with high CMV peak titers had significantly reduced overall survival (HR 2.13, 95% CI 1.53-2.96; p < .0001), due to high NRM. Early impaired T cell reconstitution was a risk factor for high CMV peak titers, however relevant CMV viremia also related to boosted T cell reconstitution. Importantly, intermediate CMV peak titers associated with a significantly reduced relapse probability (HR 0.53, 95% CI 0.31-0.91; p = .022). In short, CMV kinetics models distinguished relevant clinical outcome cohorts beyond the R+ serostatus with distinct immune reconstitution patterns and resolve in part contradicting results of previous studies exclusively focused on the presence or absence of CMV.

Sequential allogeneic hematopoietic stem cell transplantation for active refractory/relapsed myeloid malignancies: results of a reduced-intensity conditioning preceded by clofarabine and cytosine arabinoside, a retrospective study on behalf of the SFGM-TC

Allogeneic stem cell transplantation (allo-SCT) represents the most beneficial treatment for patients with active relapsed/refractory (R/R) hematologic malignancies. Recently, sequential regimens combining debulking chemotherapy followed by reduced-intensity conditioning (RIC) have shown encouraging results for these patients. In this retrospective study, we report the extended results of a sequential regimen of clofarabine, cytosine arabinoside, and RIC in 131 adults with active R/R myeloid disease at transplant. Conditioning consisted of clofarabine (30 mg/m²/day) and cytosine arabinoside (1 g/m²/day) for 5 days, followed, after a rest of 3 days, by an RIC combining cyclophosphamide (60 mg/kg) for 1 day, iv busulfan (3.2 mg/kg/day) for 2 days, and anti-thymocyte globulin (2.5 mg/kg/day) for 2 days. Between 2007 and 2016, 131 patients (males n = 75, median age: 52.6 years) were identified from the SFGM-TC registry. There were 111 acute myeloid leukemia (AML) patients and 20 cases with myelodysplastic or myeloproliferative syndrome. Status at transplant was known for all but 4 patients and was primary refractory (n = 81) and 1st or 2nd relapse (n = 46). All patients received allo-SCT from a matched donor (sibling n = 64, unrelated n = 67). Engraftment was observed in 105/122 (86%) evaluable cases and 63% of the patients achieved complete remission (CR) after transplant. The 1-year overall survival, disease-free survival, relapse incidence, non-relapse mortality, and graft-versus-host disease-free/relapse-free survival were 39.2%, 28.1%, 41.0%, 30.8%, and 22.2%, respectively. This study confirms that this sequential clofarabine-based regimen provides a high CR rate in this critical population, although relapse remains a matter of concern.

Favorable Effect of Cytomegalovirus Reactivation on Outcomes in Cord Blood Transplant and Its Differences Among Disease Risk or Type

The effects of cytomegalovirus (CMV) reactivation on cord blood transplant (CBT) are unclear. We assessed the effect of CMV reactivation in adult single-unit CBT without in vivo T cell depletion. Of 3147 eligible cases, 2052 were acute myeloid leukemia (AML), 643 acute lymphoblastic leukemia (ALL), and 452 myelodysplastic syndrome (MDS). CMV reactivation up to 100 days after CBT was associated with better overall survival (OS) compared with no reactivation cases (57.3% versus 52.6% at 3 years after CBT), whereas nonrelapse mortality (NRM) was increased in ALL (16.2% versus 8.9%) and standard disease risk (17.1% versus 10.6%, P = .014) by CMV reactivation. On multivariate analysis, CMV reactivation had favorable effects on relapse in MDS (hazard ratio [HR], .55; P = .044) and high disease risk (HR, .77; P = .047). In NRM, only standard-risk cases showed adverse effects of CMV reactivation (HR, 1.56; P = .026). OS was significantly improved with CMV reactivation in a subgroup of patients with AML (HR, .84; P = .044), MDS (HR, .68; P = .048), and high disease risk (HR, .81; P = .013). This favorable effect of CMV reactivation on OS in AML and high disease risk cases was maintained even after considering the effect of grades II to IV acute graft-versus-host disease. Thus, CMV reactivation might have beneficial or adverse effects on relapse, NRM, and OS, depending on the disease type or disease risk.

Influence of donor KIR genotypes on reduced relapse risk in acute myelogenous leukemia after hematopoietic stem cell transplantation in patients with CMV reactivation

Multiple retrospective studies have demonstrated an association between cytomegalovirus (CMV) reactivation and reduced risk of AML relapse. However, the potential mechanism explaining this association remains elusive. We investigated a homogeneous cohort of 288 adult patients with AML in remission who received allogeneic hematopoietic stem cell transplantation (HCT) from matched sibling/unrelated donors between 1995 and 2011. The 5-year cumulative incidence of relapse was greater in patients without CMV reactivation compared with those with reactivation (30.2% vs. 12.1%, p = 0.001) in a landmark analysis. In multivariate analyses CMV reactivation was independently associated with reduced relapse risk (HR: 0.49 [0.25-0.95], p = 0.036) and increased non-relapse mortality (26.5% vs. 13.1%, p = 0.002) resulting in similar 5-year overall survival (64.5% vs. 59.1%, p = 0.8). In further subgroup analyses the protective effect of CMV reactivation was significant in patients who received HCT from donors with KIR Bx compared to KIR AA (11.7% vs. 29.5%, p = 0.01). Likewise, the protective effect of CMV reactivation was more significant when the donors had 2DS1 activating KIR (11.5% vs. 30.7%, p = 0.05) compared with those without 2DS1 (14.3% vs. 27.5%, p = 0.12). Our data independently confirmed the association between CMV reactivation and AML relapse, suggesting the involvement of donor KIR genotypes and NK cell-mediated graft-versus-leukemia effect.

Adaptive NK cell reconstitution is associated with better clinical outcomes

BACKGROUND

Human cytomegalovirus (CMV) reactivation is a common occurrence early after transplant and is associated with heterogeneous NK cell subset expansion. These adaptive NK cell expansions are highly variable between recipients, with respect to magnitude and relative frequencies of adaptive NK cell subsets.

METHODS

To gain insight into the factors that influence adaptive NK cell expansion from a CMV naive graft source, we performed a high-resolution NK cell and CD8+ T cell phenotypic analysis of 215 patients with hematological malignancies that were transplanted with 2 partially HLA matched CMV negative umbilical cord blood units.

RESULTS

We found that adaptive NK cells were significantly higher in recipients who received nonmyeloablative conditioning (NMAC) relative to myeloablative conditioning (MAC), and high CMV neutralizing antibody titers correlated with the degree of adaptive NK cell expansion. The frequencies of adaptive NK cell subsets (defined by NKG2C, FcεRγ, EAT-2, and SYK expression) that reconstitute from donor hematopoietic progenitor cells largely matched the frequencies observed in the NK cell compartment of the recipient prior to conditioning, suggesting that host - as well as viral reactivation factors - may determine the phenotypic diversification after transplant. Additionally, multivariable analyses show that higher adaptive NK cell expansion associated with better disease-free survival.

CONCLUSIONS

Our findings provide important insights into adaptive NK cell reconstitution after transplant and support a role for adaptive NK cells in promoting better clinical outcomes.

FUNDING

The NIH and the National Marrow Donor Program.

Cytomegalovirus: an unlikely ally in the fight against blood cancers?

Cytomegalovirus (CMV) infection is a potentially fatal complication in patients receiving haematopoietic stem cell transplantation (HSCT), but recent evidence indicates that CMV has strong anti-leukaemia effects due in part to shifts in the composition of natural killer (NK) cell subsets. NK cells are the primary mediators of the anti-leukaemia effect of allogeneic HSCT, and infusion of allogeneic NK cells has shown promise as a means of inducing remission and preventing relapse of several different haematological malignancies. The effectiveness of these treatments is limited, however, when tumours express human leucocyte antigen (HLA)-E, a ligand for the inhibitory receptor NKG2A, which is expressed by the vast majority of post-transplant reconstituted and ex-vivo expanded NK cells. It is possible to enhance NK cell cytotoxicity against HLA-Epos malignancies by increasing the proportion of NK cells expressing NKG2C (the activating receptor for HLA-E) and lacking the corresponding inhibitory receptor NKG2A. The proportion of NKG2Cpos /NKG2Aneg NK cells is typically low in healthy adults, but it can be increased by CMV infection or ex-vivo expansion of NK cells using HLA-E-transfected feeder cells and interleukin (IL)-15. In this review, we will discuss the role of CMV-driven NKG2Cpos /NKG2Aneg NK cell expansion on anti-tumour cytotoxicity and disease progression in the context of haematological malignancies, and explore the possibility of harnessing NKG2Cpos /NKG2Aneg NK cells for cancer immunotherapy.

Cytomegalovirus induces HLA-class-II-restricted alloreactivity in an acute myeloid leukemia cell line

Cytomegalovirus (HCMV) reactivation is found frequently after allogeneic hematopoietic stem cell transplantation (alloSCT) and is associated with an increased treatment-related mortality. Recent reports suggest a link between HCMV and a reduced risk of cancer progression in patients with acute leukemia or lymphoma after alloSCT. Here we show that HCMV can inhibit the proliferation of the acute myeloid leukemia cell line Kasumi-1 and the promyeloid leukemia cell line NB4. HCMV induced a significant up-regulation of HLA-class-II-molecules, especially HLA-DR expression and an increase of apoptosis, granzyme B, perforin and IFN-γ secretion in Kasumi-1 cells cocultured with peripheral blood mononuclear cells (PBMCs). Indolamin-2,3-dioxygenase on the other hand led only to a significant dose-dependent effect on IFN-γ secretion without effects on proliferation. The addition of CpG-rich oligonucleotides and ganciclovir reversed those antiproliferative effects. We conclude that HCMV can enhance alloreactivity of PBMCs against Kasumi-1 and NB4 cells in vitro. To determine if this phenomenon may be clinically relevant further investigations will be required.

Role of thymoglobulin in matched sibling allogeneic hematopoietic stem cell transplantation with busulfan and fludarabine conditioning in myeloid malignanicies

In vivo T-cell depletion using anti-thymocyte globulin (ATG) is widely used in allogeneic hematopoietic stem cell transplantation (HSCT) for prophylaxis of GvHD. We investigated the influence of thymoglobulin dose (an ATG) on GvHD following matched sibling donor (MSD) HSCT with a busulfan and fludarabine preparative regimen. Medical records of 180 patients who received MSD HSCT with a conditioning regimen of busulfan, fludarabine, and ATG (BuFluATG) were reviewed retrospectively. The median age was 53 years (range 18-68). Initial diagnoses were acute myeloid leukemia (73.3%) and myelodysplastic syndrome (26.7%). Forty-four and 68 patients (24.4 and 37.7%) experienced acute and chronic GvHD of any grade, respectively. High-dose (⩾4.5 mg/kg) ATG was independently associated with decreased risk of acute GvHD (hazard ratio=0.36, 95% confidence interval (CI): 0.15-0.84, P=0.019) compared to low-dose ATG (<4.5 mg/kg). Although ATG dose was associated with the risk of acute GvHD, it was not associated with the risk of chronic GvHD in our study. A higher dose (⩾4.5 mg/kg) of ATG decreases the risk of acute GvHD but had no significant impact on disease-free survival in MSD HSCT patients conditioned with BuFluATG. The optimal dose of ATG should be further investigated in a large prospective study context.

Cytomegalovirus reactivation is associated with a lower rate of early relapse in myeloid malignancies independent of in-vivo T cell depletion strategy

The association between cytomegalovirus (CMV) reactivation and relapse risk has not been evaluated in relation to T cell depletion strategies. We evaluated 93 patients who underwent allogeneic hematopoietic stem cell transplantation (HSCT) and analyzed the association between T cell depletion strategies with the cumulative incidence of relapse and CMV reactivation. A total of 33% of patients who received ATG vs. 34% who received alemtuzumab developed CMV reactivation. The cumulative incidence of relapse was 3% at 1year and 20% at 3 years in patients with CMV reactivation vs. 30% at 1year and 38% at 3 years in patients without CMV reactivation (p=0.02). When analyzed separately, this effect persisted in the myeloid, but not the lymphoid group. There was a numerical trend towards increased non-relapse mortality (NRM) in patients with CMV reactivation, especially in the myeloid group. The choice of T cell depleting agent and the rate of CMV reactivation were not associated with different overall survival (OS) rates. These results suggest that the choice of T cell depletion strategy may have similar effects on rates of CMV reactivation, disease relapse, and survival. Further studies examining these variables in patients not exposed to in-vivo T cell depleting agents may be of interest.

Naive Donor NK Cell Repertoires Associated with Less Leukemia Relapse after Allogeneic Hematopoietic Stem Cell Transplantation

Acute and latent human CMV cause profound changes in the NK cell repertoire, with expansion and differentiation of educated NK cells expressing self-specific inhibitory killer cell Ig-like receptors. In this study, we addressed whether such CMV-induced imprints on the donor NK cell repertoire influenced the outcome of allogeneic stem cell transplantation. Hierarchical clustering of high-resolution immunophenotyping data covering key NK cell parameters, including frequencies of CD56(bright), NKG2A(+), NKG2C(+), and CD57(+) NK cell subsets, as well as the size of the educated NK cell subset, was linked to clinical outcomes. Clusters defining naive (NKG2A(+)CD57(-)NKG2C(-)) NK cell repertoires in the donor were associated with decreased risk for relapse in recipients with acute myeloid leukemia and myelodysplastic syndrome (hazard ratio [HR], 0.09; 95% confidence interval [CI]: 0.03-0.27; p < 0.001). Furthermore, recipients with naive repertoires at 9-12 mo after hematopoietic stem cell transplantation had increased disease-free survival (HR, 7.2; 95% CI: 1.6-33; p = 0.01) and increased overall survival (HR, 9.3; 95% CI: 1.1-77, p = 0.04). Conversely, patients with a relative increase in differentiated NK cells at 9-12 mo displayed a higher rate of late relapses (HR, 8.41; 95% CI: 6.7-11; p = 0.02), reduced disease-free survival (HR, 0.12; 95% CI: 0.12-0.74; p = 0.02), and reduced overall survival (HR, 0.07; 95% CI: 0.01-0.69; p = 0.02). Thus, our data suggest that naive donor NK cell repertoires are associated with protection against leukemia relapse after allogeneic HSCT.