Cytomegalovirus-Specific Immunity Recovers More Slowly after Cord Blood Transplantation Compared with Matched Sibling Donor Allogeneic Transplantation.

BACKGROUND: Rapid quantitative recovery of NK cells but slower recovery of T-cell subsets along with frequent viral infections are reported after umbilical cord blood (UCB) compared with matched sibling donor (MSD) hematopoietic cell transplantation (HCT). However, it remains unclear whether increased propensity for viral infections is also a result of slower recovery of virus-specific immunity after UCB as compared to MSD HCT. OBJECTIVES: We examined the differences in the function of virus-specific peripheral blood mononuclear cells (PBMC) after UCB (N=17) vs. MSD (N=9) using previously collected patient blood samples at various time points after HCT. METHODS: Interferon-gamma (IFN-γ) enzyme-linked immune absorbent spot (ELISpot) assay was used to quantify the PBMC frequencies that secrete IFN-γ in response to 11 immunopeptides from 5 common viruses. We included the patients who received the same reduced intensity conditioning regimen without ATG, no systemic glucocorticoids and had no relapse or acute/chronic graft-versus-host disease within 1 year after HCT. RESULTS: The CMV-reactive PBMC frequencies were higher in CMV seropositive vs. seronegative patients after HCT. Among CMV seropositive patients, the frequency of CMV-reactive PBMC was lower after UCB compared to MSD throughout one year of HCT. We observed no differences in virus-specific PBMC responses towards HHV6, EBV, BK, and adenovirus antigens between UCB and MSD. CONCLUSION: Our data demonstrate that the reconstitution of CMV-specific immunity is slower in CMV seropositive recipients of UCB vs. MSD HCT in contrast to other viruses which had similar recoveries. These study findings support implementation of more potent prophylactic strategies for preventing CMV reactivation in CMV seropositive patients receiving UCB HCT.

Improving outcomes after allogeneic hematopoietic cell transplantation for Hodgkin lymphoma in the brentuximab vedotin era.

Allogeneic hematopoietic cell transplantation (alloHCT) remains a valuable treatment alternative for relapsed/refractory (R/R) Hodgkin lymphoma (HL). Data on alloHCT outcomes in the era of new HL therapies are needed. We evaluated 72R/R HL patients who received reduced intensity conditioning alloHCT and compared the time periods 2009-2013 (n=20) with 2000-2008 (n=52). Grafts included HLA-matched sibling (35%), unrelated donor (8%) and umbilical cord blood (56%). In the recent period, patients more often received brentuximab vedotin (BV, 60% vs 2%), had fewer comorbidities (Sorror index 0: 60% vs 12%) and were in complete remission (50% vs 23%). Median follow-up was 4.4 years. Three-year PFS improved for patients treated between 2009 and 2013 (49%, 95% CI 26-68%) as compared with the earlier era (23%, 95% CI 13-35%, P=0.02). Overall survival (OS) at 3 years was 84% (95% CI 57-94%) vs 50% (95% CI 36-62%, P=0.01), reflecting lower non-relapse mortality and relapse rates. In multivariate analysis mortality was higher among those with chemoresistance (HR 3.83, 95% CI 1.38-10.57), while treatment during the recent era was associated with better OS (HR for period 2009-2013: 0.24, 95% CI 0.07-0.79) and PFS (HR 0.46, 95% CI 0.23-0.92). AlloHCT in patients with R/R HL is now a more effective treatment than previously.

CD56dimCD57+NKG2C+ NK cell expansion is associated with reduced leukemia relapse after reduced intensity HCT.

We have recently described a specialized subset of human natural killer (NK) cells with a CD56(dim)CD57(+)NKG2C(+) phenotype that expand specifically in response to cytomegalovirus (CMV) reactivation in hematopoietic cell transplant (HCT) recipients and exhibit properties characteristic of adaptive immunity. We hypothesize that these cells mediate relapse protection and improve post-HCT outcomes. In 674 allogeneic HCT recipients, we found that those who reactivated CMV had lower leukemia relapse (26% (17-35%), P=0.05) and superior disease-free survival (DFS) (55% (45-65%) P=0.04) 1 year after reduced intensity conditioning (RIC) compared with CMV seronegative recipients who experienced higher relapse rates (35% (27-43%)) and lower DFS (46% (38-54%)). This protective effect was independent of age and graft-vs-host disease and was not observed in recipients who received myeloablative regimens. Analysis of the reconstituting NK cells demonstrated that CMV reactivation is associated with both higher frequencies and greater absolute numbers of CD56(dim)CD57(+)NKG2C(+) NK cells, particularly after RIC HCT. Furthermore, expansion of these cells at 6 months posttransplant independently trended toward a lower 2-year relapse risk. Together, our data suggest that the protective effect of CMV reactivation on posttransplant relapse is in part driven by adaptive NK cell responses.

The effect of equine antithymocyte globulin on the outcomes of reduced intensity conditioning for AML.

Whether or not the benefits of antithymocyte globulin (ATG) on engraftment and GVHD are offset by increased risk of relapse, delayed T-cell recovery and increased infections remains controversial. We retrospectively studied the effect of ATG in 144 AML patients, 34 of whom received ATG, undergoing reduced intensity conditioning (RIC) umbilical cord blood transplantation (UCB) or HLA-matched sibling PBSC. ATG patients had not received intensive chemotherapy for 3 months before transplantation for UCB, 6 months for PBSC. There were no differences in engraftment between ATG and non-ATG patients. The cumulative incidences of TRM as well as acute and chronic GVHD in ATG-treated patients were not statistically different. ATG patients had significantly more infections between 46 and 180 days post transplantation. Unexpectedly, after adjusting for donor type, relapse was lower among ATG recipients (relative risk (RR) 0.5, 95% confidence interval (CI) 0.3-1.0, P=0.04). In summary, administration of ATG to AML patients undergoing RIC had no adverse impact on major clinical outcomes. ATG may be indicated for patients at higher risk of graft failure after allogeneic hematopoietic cell transplantation (allo-HCT).

Higher therapeutic CsA levels early post transplantation reduce risk of acute GVHD and improves survival.

We studied whether early CsA trough levels were associated with the risk of acute GVHD in 337 patients after either sibling PBSC or double umbilical cord blood transplantation. All patients, regardless of donor type, started CsA at a dose of 5 mg/kg i.v. divided twice daily, targeting trough concentrations 200-400 ng/mL. The CsA level was studied by a weighted average method calculated by giving 70% of the weight to the level that was measured just before the onset of the event or day +30. We found that higher weighted average CsA trough levels early post transplantation contributed to lower risk of acute GVHD, and lower non-relapse and overall mortality. Thus, our data support close monitoring with active adjustments of CsA dosing to maintain therapeutic CsA levels in the first weeks of allo-HCT. In patients who are near or even modestly above the CsA target trough level, in the absence of CsA-related toxicity, dose reduction should be cautious to avoid subtherapeutic drug levels resulting in higher risk of acute GVHD.

Reduced-intensity hematopoietic cell transplantation in older patients with AML/MDS: umbilical cord blood is a feasible option for patients without HLA-matched sibling donors.

Umbilical cord blood (UCB) has increased access to hematopoietic cell transplantation (HCT) for patients without HLA-matched sibling donors (MSD). We compared outcomes of HCT using MSD (N=38) or UCB (N=60) among older patients (age ≥ 55 years) with AML or myelodysplastic syndromes (MDS). All patients received a reduced intensity regimen consisting of CY, fludarabine and 200 cGy TBI. Median age at HCT was 63 years for MSD and 61 years for UCB recipients. Among UCB recipients, 95% received two UCB units and 88% received 1-2 locus HLA-mismatched units to optimize cell dose. OS at 3-years was 37% for MSD and 31% for UCB recipients (P=0.21). On multivariate analysis, donor source (MSD vs UCB) did not impact risks of OS, leukemia-free survival and relapse or treatment-related mortality. UCB is feasible as an alternative donor source for reduced-intensity conditioning HCT among older patients with AML and MDS who do not have a suitable MSD.

Factors predicting single-unit predominance after double umbilical cord blood transplantation.

Double umbilical cord blood transplantation (dUCBT), developed as a strategy to treat large number of patients with hematologic malignancies, frequently leads to the long-term establishment of a new hematopoietic system maintained by cells derived from a single umbilical cord blood unit. However, predicting which unit will predominate has remained elusive. This retrospective study examined the risk factor associated with unit predominance in 262 patients with hematologic malignancies who underwent dUCBT with subsequent hematopoietic recovery and complete chimerism between 2001 and 2009. Dual chimerism was detected at day 21-28, with subsequent single chimerism in 97% of the cases by day +100 and beyond. Risk factors included nucleated cell dose, CD34+ and CD3+ cell dose, colony-forming units-granulocyte macrophage dose, donor-recipient HLA match, sex and ABO match, order of infusion and cell viability. In the myeloablative setting, CD3+ cell dose was the only factor associated with unit predominance (odds ratio (OR) 4.4, 95% confidence interval (CI) 1.8-10.6; P<0.01), but in the non-myeloablative setting, CD3+ cell dose (OR 2.1, 95%CI 1.0-4.2; P=0.05) and HLA match (OR 3.4, 95%CI 1.0-11.4; P=0.05) were independent factors associated with unit predominance. Taken together, these findings suggest that immune reactivity has a role in unit predominance, and should be considered during graft selection and graft manipulation.

Delayed platelet recovery after allogeneic transplantation: a predictor of increased treatment-related mortality and poorer survival.

Delayed platelet recovery (DPR) is common after allo-SCT. Insufficient data on risk factors and association with OS and TRM are available. We conducted a retrospective analysis of all allografts at the University of Minnesota between 2000 and 2005 to characterize the frequency of DPR (platelets <50 000/µL by day 60), risk factors and related complications. A total of 850 patients with hematological malignancies and benign disorders were included. Myeloablative (MA) conditioning was used in 65% of the patients and 45% received umbilical cord blood (UCB) grafts. The 60-day cumulative incidence of platelet recovery was 40% in UCB, 57% in unrelated donor (URD) and 74% in sibling donor. Multivariate analysis confirmed that the variables associated with DPR were MA (versus reduced intensity) conditioning, graft source other than sibling donor, ABO major mismatch, recipient CMV-positive serostatus, the presence of grade II-IV acute GVHD and slower neutrophil recovery. These data demonstrate that DPR is frequent after allogeneic hematopoietic cell transplantation, especially after UCB. DPR is a significant independent risk factor for increased TRM and poorer OS along with HLA-mismatched URD, but not UCB, grade II-IV acute GVHD, old age and advanced disease stage.

High fludarabine exposure and relationship with treatment-related mortality after nonmyeloablative hematopoietic cell transplantation.

Despite its common use in nonmyeloablative preparative regimens, the pharmacokinetics of fludarabine are poorly characterized in hematopoietic cell transplantation (HCT) recipients and exposure-response relationships remain undefined. The objective of this study was to evaluate the association between plasma F-ara-A exposure, the systemically circulating moiety of fludarabine, and engraftment, acute GVHD, TRM and OS after HCT. The preparative regimen consisted of CY 50 mg/kg/day i.v. day -6; plus fludarabine 30-40 mg/m²/day i.v. on days -6 to -2 and TBI 200 cGy on day -1. F-ara-A pharmacokinetics were carried out with the first dose of fludarabine in 87 adult patients. Median (range) F-ara-A area-under-the-curve (AUC((0-∞))) was 5.0 µg h/mL (2.0-11.0), clearance 15.3 L/h (6.2-36.6), C(min) 55 ng/mL (17-166) and concentration on day(zero) 16.0 ng/mL (0.1-144.1). Despite dose reductions, patients with renal insufficiency had higher F-ara-A exposures. There was strong association between high plasma concentrations of F-ara-A and increased risk of TRM and reduced OS. Patients with an AUC((0-∞)) greater than 6.5 µg h/mL had 4.56 greater risk of TRM and significantly lower OS. These data suggest that clinical strategies are needed to optimize dosing of fludarabine to prevent overexposure and toxicity in HCT.

Umbilical cord blood: current status and future directions.

Once considered biological waste, umbilical cord blood (UCB) has become an accepted source of haematopoietic stem cells (HSCs). With initial success in the pediatric setting, UCB transplantation continues to gain favor in the adult patient population. Novel approaches to UCB transplantation include use of two units and a variety of graft manipulations. Additional uses for UCB are currently being explored and include applications in regenerative medicine and immunotherapy.

Going straight to the point: intra-BM injection of hematopoietic progenitors.

Intra-BM injection (IBMI) has been used clinically as a technique to deliver medications, blood products and fluids to critically ill children and war-wounded soldiers. Interest in IBMI has now been renewed in the setting of hematopoietic cell transplantation, in particular when umbilical cord blood is the graft source. Clinical studies have not yet unequivocally shown improvement in hematopoietic recovery. However, most intriguing is the observation, both in the clinical setting and in murine models, that the IBMI delivery of hematopoietic grafts and lymphocytes may reduce in the risk of acute GVHD. The underlying mechanism of the reduced risk of GVHD requires further investigation. In this study, we review the rationale as well as the clinical and pre-clinical data that support the study of IBMI as a method to deliver hematopoietic cells.

A modified comorbidity index for hematopoietic cell transplantation.

A recent validation analysis at our center among allogeneic hematopoietic cell transplant (HCT) recipients did not find the HCT-specific comorbidity index (HCT-CI) to clearly segregate patient's transplant-related risk. We hypothesized that the discriminating and predictive power of the HCT-CI for mortality could be improved by eliminating the assignment of categorical weights to comorbidities and instead replacing them with hazard ratios (HR) from a Fine and Gray adjusted regression model. This approach allowed us to look carefully at each component of the comorbidity index. We developed the modified comorbidity index (MCI) using a cohort of 444 adult allogeneic HCT recipients using a pure multiplicative model. Compared with low-risk patients, the HR for non-relapse mortality (NRM) using the HCT-CI was 1.3 (95% confidence intervals, 0.7-2.4) for intermediate risk and 1.6 (0.9-2.8) for high-risk patients, and with the MCI was 1.6 (0.9-2.8) and 2.7 (1.5-5.0), respectively. In conclusion, we are introducing the MCI which may have higher discriminating and predictive power for overall survival and NRM. Validation of the HCT-CI and the MCI in larger and separate cohorts of HCT recipients is still needed.

Future of cord blood for oncology uses.

The utilization of umbilical cord blood (UCB) as a source of stem cells for transplantation has grown substantially in the last decade. Already an established practice for the treatment of children with hematological malignancies, its application for the treatment of adults is also expanding. The development of the double UCB and reduced-intensity transplantation platforms have contributed to this expansion. Recent registry-based analysis and ongoing single institution and multicenter clinical trials are investigating ways to make UCB transplantation more widely available. We review here the background data on the utilization of UCB for the treatment of hematological malignancies, and discuss the current challenges and future directions in the field of UCB transplantation.

Intra-BM injection to enhance engraftment after myeloablative umbilical cord blood transplantation with two partially HLA-matched units.

The time to neutrophil engraftment for adult patients after myeloablative double unit umbilical cord blood (UCB) transplantation is 23 days when the two units are given i.v. We hypothesized that the intra-BM injection (IBMI) of one of the two UCB units would reduce systemic loss of hematopoietic progenitors and shorten time to neutrophil recovery after myeloablation. Ten patients with a median age of 35 years were transplanted. The unit to be given by IBMI was randomly assigned; the other unit was given i.v. The median infused graft total nucleated cell dose was 3.7 x 10(7)/kg with no difference between i.v. and IBMI units. All patients tolerated the procedure well, and there was no severe adverse event related to IBMI. The median time to neutrophil engraftment and plt recovery >50 000/microl was 21 and 69 days, respectively. In all, 9 of 10 patients engrafted, 5 with the i.v. unit and 4 with the IBMI unit; 7 of 8 evaluable patients developed acute GVHD and 5 of 10 patients died from treatment-related causes. Survival was 47% at 1 year. Despite safety of administration, IBMI of one of two UCB units did not shorten the time to neutrophil engraftment and offers no advantage over conventional double unit transplantation.

Fewer infections and lower infection-related mortality following non-myeloablative versus myeloablative conditioning for allotransplantation of patients with lymphoma.

Non-myeloablative (NMA) allogeneic donor SCT for patients with relapsed lymphoma is associated with lower treatment-related mortality (TRM). However, the impact of conditioning intensity on post transplant infections remains unclear. We evaluated infections in 141 consecutive patients with lymphoma who were allografted using NMA (n=76) or myeloablative (MA; n=65) conditioning regimens. Using infection incidence density per 1000 patient days, we accounted for all infectious episodes during the first post transplant year. Before neutrophil engraftment, the NMA cohort had a 53% lower rate of bacterial infection (relative risk=0.47; P=0.06), whereas after engraftment the density of bacterial infections was similar in the two groups. In the first month, both invasive fungal infections and viral infections were twofold less frequent (P=0.22; P=0.06) in NMA patients. Late viral and fungal infections as well as CMV reactivation were infrequent after either conditioning intensity. The 1-year infection-related mortality was significantly lower after NMA conditioning (NMA 9% (3-16%) vs MA 22% (11-40%); P=0.03). NMA allogeneic transplantation for lymphoma patients results in substantially fewer early infections and lower infection-related deaths, although the similar frequency of later infections suggests that immune reconstitution is delayed with either conditioning intensity.

Infectious complications following unrelated cord blood transplantation.

INTRODUCTION: Infections following cord blood transplantation are just beginning to be defined in the literature. This review will outline infections at death, the epidemiology of individual infections, and the impact of stem cell source. METHODS: A review of studies published since 2000. RESULTS: Based on registry data, most studies demonstrate an approximate rate of infection at death of 30-40% among cord blood recipients. Bacterial infections often occur prior to engraftment and increase among patients with graft failure. In addition, there is delayed recovery of the immune response among patients with graft-versus-host disease that leads to viral infections at later time points. The risk of serious infection among children receiving umbilical cord blood (UCB) grafts is comparable to that of children receiving unmanipulated marrow and is lower than that of recipients of a T-cell-depleted stem cell source. Among adult patients, despite an overall higher incidence of serious infections after UCB transplantation as compared with unrelated donor grafts, non-relapse mortality and overall survival were not significantly different between haematopoietic stem cell sources. CONCLUSIONS: Further studies are needed to confirm these observations and determine whether the risk of infection for cord blood recipients is comparable to that of recipients of unmanipulated marrow.

Leukemia in donor cells after allogeneic hematopoietic stem cell transplant.

The development of leukemia in donor cells after allogeneic hematopoietic stem cell transplant is an extremely rare event. We report here the case of a patient who developed myelodysplastic syndrome/acute myeloid leukemia, in cells of donor origin 3.5 years after related donor HSCT for refractory chronic lymphocytic leukemia and therapy-induced myelodysplastic syndrome. The origin of the leukemia was determined by analysis of minisatillite polymorphism tested on CD34(+) cells.