Effect of multiple HLA-locus mismatches on outcomes after single cord blood transplantation

BACKGROUND

Effect of single or multiple mismatches at each HLA locus on outcomes after cord blood transplantation (CBT) is controversial.

OBJECTIVE

We analyzed the effects of single or multiple HLA-locus mismatches on the outcomes after single CBT using a Japanese registry data from the Japan Society for Hematopoietic Cell Transplantation (JSHCT).

STUDY DESIGN

Patients with acute leukemia and myelodysplastic syndromes, aged 16 years or older, who underwent their first CBT between 2003 and 2017 (n = 4,074) were included. The effect of the number of HLA-locus mismatches (0, 1, and 2, for the HLA-A, -B, -C, and -DRB1 loci) on outcomes was analyzed after adjusting for other significant variables.

RESULTS

The median age of the patients was 54 years. Median total nucleated and CD34 cell doses were 2.6 × 10⁷/kg and 0.8 × 10⁵/kg, respectively. The number of CBTs with single or double mismatches were 2,099 and 292 for HLA-A locus, 2,699 and 341 for HLA-B locus, 2,555 and 609 for HLA-C locus, and 2,593 and 571 for HLA-DRB1 locus, respectively. Single and double HLA-DRB1 mismatches were associated with a higher risk of grade II-IV acute graft-versus-host disease (GVHD, single: HR 1.29, P<0.001, double: HR 1.49, P<0.001, trend-P: P<0.001). Single and double mismatches at HLA-DRB1 as well as single mismatches at HLA-A and HLA-B were also associated with grade III-IV acute GVHD. Single and double HLA-B mismatches and double HLA-DRB1 mismatches were associated with a high risk of non-relapse mortality. On the other hand, double mismatches at HLA-A or HLA-DRB1 and single mismatches at HLA-B were associated with a lower risk of relapse.

CONCLUSION

HLA-DRB1 double mismatch was associated with high risks of grade II-IV and III-IV acute GVHD and non-relapse mortality but lower risk of relapse. Not only the locus mismatch but also the number of mismatches may be considered in cord blood unit selection.

Ideal body weight is useful for predicting neutrophil engraftment and platelet recovery for overweight and obese recipients in single-unit cord blood transplantation

BACKGROUND

Since cord blood (CB) units are usually selected based on the cell dose /kg, overweight (25 kg/m² ≤ body mass index (BMI) < 30 kg/m²) and obese (30 kg/m² ≤ BMI) recipients tend to have difficulty in getting appropriate CB units. In general, actual body weight (ABW) is used for CB unit selection. However, ideal body weight (IBW) has been reported to be more closely correlated with successful engraftment after autologous, allogeneic bone marrow, and peripheral blood stem cell transplantation than ABW.

OBJECTIVES

We conducted this analysis to clarify the threshold of CD34⁺ cell doses based on ideal body weight (CD34^IBW) and to compare the outcomes among the groups stratified by the threshold according to actual body weight (CD34^ABW) and CD34^IBW for overweight and obese recipients in cord blood transplantation (CBT).

STUDY DESIGN

We retrospectively analyzed 650 overweight and obese recipients who received single-unit CBT. To focus on the recipients who received a low CD34⁺ cell dose /kg, those who received 1.5×10⁵ CD34⁺ cells /ABW or more were excluded. Using a cut-off of 0.8×10⁵ CD34⁺ cells/kg, we compared the outcomes in 3 groups with low CD34^ABW and low CD34^IBW (CD34^Low/Low), low CD34^ABW but high CD34^IBW (CD34^Low/High), and high CD34^ABW and high CD34^IBW (CD34^High/High).

RESULTS

Hematopoietic recoveries were significantly delayed in the CD34^Low/Low group compared with those in the CD34^Low/High group (hazard ratio (HR) 0.67 for neutrophil, P < 0.001; HR 0.72 for platelet, P = 0.014), while those were comparable in the CD34^Low/High and CD34^High/High groups (HR 1.22 for neutrophil, P = 0.16; HR 1.29 for platelet, P = 0.088). Moreover, the CD34^Low/High group demonstrated longer overall survival than the CD34^Low/Low group (HR 1.48, P = 0.011) and comparable survival to the CD34^High/High group (HR 0.93, P = 0.68).

CONCLUSIONS

This finding may address the lack of availability of CB units for some overweight and obese recipients for whom suitable donors are unavailable. Further investigations are warranted to evaluate the appropriateness of ABW and IBW.

Long-term incidence of varicella zoster virus disease in adults receiving single-unit cord blood transplantation

BACKGROUND

Varicella zoster virus (VZV) disease is a common complication after allogeneic hematopoietic cell transplantation (HCT). However, research into the long-term incidence of VZV disease in adults receiving cord blood transplantation (CBT) has been limited.

OBJECTIVE

The objective of this study was to evaluate the incidence, risk factors, and clinical impact of VZV disease after CBT with a long-term follow-up in our institute.

STUDY DESIGN

We retrospectively analyzed the data for 156 adult patients who received single-unit CBT at our institute between 2007 and 2020, who achieved neutrophil engraftment and survived at least 100 days without recurrence of the underlying disease.

RESULTS

VZV disease occurred in 61 patients at a median of 608 days (range, 36 - 4090 days) after CBT. The cumulative incidence of VZV disease was 14% (95% confidence interval [CI], 9% to 20%) at 1 year and 40% (95% CI, 31% to 48%) at 5 years after CBT. Multivariate analysis showed that the cessation of antiviral prophylaxis was an independent risk factor for a higher risk of VZV disease (hazard ratio: 15.65, 95% CI: 6.59-37.21, P<0.001). The cumulative incidence of VZV disease was significantly lower in the long-term antiviral prophylaxis group given for around 1 year after CBT or the end of immunosuppressive therapy compared to the short-term antiviral prophylaxis group given for 35 days after CBT (P=0.005). Among patients who developed VZV disease, the median onset of VZV disease was significantly delayed in the long-term antiviral prophylaxis group compared to the short-term antiviral prophylaxis group (694 days vs 130 days, P<0.001), but the median onset of VZV disease after the cessation of antiviral prophylaxis was not significantly different between long-term and short-term antiviral prophylaxis (166 days vs 95 days, P=0.087).

CONCLUSION

These data demonstrated that the long-term incidence of VZV disease was relatively high in adult patients receiving CBT. Given that the incidence of VZV disease after the cessation of antiviral prophylaxis remained high, additional interventions, such as recombinant zoster vaccine administration, could be required to prevent VZV disease in long-term adult survivors after CBT.

Unrelated cord blood transplantation for adult-onset EBV-associated T-cell and NK-cell lymphoproliferative disorders

Adult-onset EBV-associated T-cell and NK-cell lymphoproliferative disorders (EBV-T/NK-LPDs) often progress rapidly, and require allogeneic stem cell transplantation early in the course of treatment. Unrelated cord blood transplantation (UCBT) is a readily available option for patients without HLA-matched donors. We retrospectively analyzed the outcomes of 12 UCBT in adult patients with chronic active EBV infection (CAEBV, n = 8), EBV-positive hemophagocytic lymphohistiocytosis following primary EBV infection (n = 2), hydroa vacciniforme-like lymphoproliferative disorder (n = 1), and systemic EBV-positive T-cell lymphoma of childhood (STCLC, n = 1). The median age at transplantation was 31.5 years (range 19-58). At the median follow-up time for survivors, which was 6.3 years (range 0.3-11.3), 3-year overall survival (OS) rates in all patients and 8 CAEBV patients were 68.2% (95% CI 28.6-88.9) and 83.3% (95% CI 27.3-97.5), respectively. Graft failure occurred in 4 of 8 CAEBV patients, requiring a second UCBT to achieve neutrophil engraftment. The cumulative incidence of grade II-IV acute GVHD was 33.3% (95% CI 9.1-60.4%). The EBV-DNA load became undetectable or very low after UCBT in all cases. UCBT may be a promising treatment option for adult-onset EBV-T/NK-LPDs.

Risk factors and outcomes of cytomegalovirus infection in children post cord blood transplantation with focus on impact of graft-versus-host disease and immunosuppressants

Cytomegalovirus (CMV) infection remains an important cause of morbidity and mortality post cord blood transplantation (CBT). It has been suggested that the graft-versus-host disease (GVHD) and immunosuppressants have an impact on CMV infection. This study evaluated the incidence, outcomes, and risk factors of CMV infection, while focusing on GVHD and the use of immunosuppressants, in 103 children who had received CBT. Among the patients, 92.2% were positive for CMV serology, while CMV antigenemia was observed in 68.9% and CMV disease developed in 26.2%. CMV enterocolitis was the most common, followed by retinitis and pneumonia. Patients with positive CMV serology and grade II to IV GVHD were independently associated with CMV antigenemia. Recurrent CMV antigenemia was observed significantly more frequently in patients with extensive chronic GVHD. Patients with CMV disease showed significantly worse overall survival, relapse-free survival, and non-relapse mortality than those without CMV disease. In conclusion, CMV infection is common post-CBT in countries with a high rate of CMV seropositivity in the general population and is related to worse outcomes. GVHD severity is associated with the development and recurrence of CMV infection. Thus, efforts need to be made to prevent CMV infection in children post-CBT.

Total body irradiation-based versus busulfan-based myeloablative conditioning for single-unit cord blood transplantation in adults

Comparative studies between total body irradiation (TBI)-based and busulfan-based myeloablative conditioning (MAC) regimens for cord blood transplantation (CBT) have been limited. We retrospectively analyzed the results of single-unit CBT in 333 adult patients who received either TBI-based (n = 258) or busulfan-based (n = 75) MAC regimens at our institute. After adjusting for significant variables in the univariate analysis, there were no significant differences in neutrophil recovery (hazard ratio (HR), 0.88; p = .460), grade III-IV acute graft-versus-host disease (GVHD) (HR: 1.40, p = .410), extensive chronic GVHD (HR: 0.73, p = .380), relapse (HR: 0.61, p = .270), non-relapse mortality (HR: 1.38, p = .420), overall survival (HR: 1.18, p = .637), or event-free survival (HR: 1.08, p = .773), although platelet recovery was lower with marginal significance for the busulfan-based regimen (HR: 0.67, p = .068). In subgroup analysis, TBI-based regimens were superior to busulfan-based regimens in terms of survival for acute lymphoblastic leukemia, but not for myeloid malignancies. Further investigation is warranted even for CBT.

Decision Analysis for Unrelated Bone Marrow Transplantation or Immediate Cord Blood Transplantation for Patients with Philadelphia Chromosome-Negative Acute Lymphoblastic Leukemia in First Complete Remission

An HLA-matched relative is the first-choice donor for patients with Philadelphia chromosome (Ph)-negative acute lymphoblastic leukemia (ALL) in first complete remission (CR1). The most promising alternative donor is thought to be an HLA-matched unrelated donor (MUD) in patients who do not have an HLA-matched related donor. Cord blood transplantation (CBT) is an alternative option. Higher rates of engraftment failure and nonrelapse mortality are significant problems, but the ready availability of cord blood can be an advantage, because patients can immediately undergo transplantation before progression. This study was conducted to identify an appropriate alternative donor in patients with Ph-negative ALL in CR1 who do not have an HLA-matched related donor (MRD). Decision analyses using a Markov model were performed to compare immediate CBT, in which CBT was performed at 1 month after the achievement of CR1, with elective unrelated bone marrow transplantation (uBMT) from an 8/8 HLA-matched unrelated donor (MUD) (8/8 uBMT) or uBMT from 7/8 MUD (7/8 uBMT), in which uBMT was performed at 4 months, in patients age 16 to 55 years with Ph-negative ALL in CR1 who did not have an MRD. We constructed a decision tree. The cycle length was set at 3 months, and analyses were performed for 19 cycles for uBMT and 20 cycles for CBT, resulting in evaluation of the 5-year life expectancy after both decisions. Transition probabilities (TPs) and utilities were estimated from prospective and retrospective Japanese studies and the registry database of Japan. Subgroup analyses were performed according to risk stratification based on WBC count and cytogenetics at diagnosis and according to age stratification, with a cutoff of 25 years. One-way sensitivity analyses for TPs and utilities were performed as well. The baseline analyses showed that 8/8 uBMT or 7/8 uBMT had superior results to CBT, with quality-adjusted life years (QALYs) of 2.86 in 8/8 uBMT, 2.84 in 7/8 uBMT, and 2.75 in CBT. One-way sensitivity analyses showed that the results of the baseline analyses were reversed if the probability of nonrelapse mortality (NRM) in CBT improved. Subgroup analyses showed similar results in younger, older, and high-risk patients. However, QALY was worse in 8/8 uBMT compared with CBT in standard-risk patients. In one-way sensitivity analyses, the probabilities of NRM in uBMT and CBT affected the baseline results in all analyses except for comparisons between 8/8 uBMT and CBT in younger and high-risk patients. In these 2 populations, the superiority of 8/8 uBMT was consistently demonstrated throughout the one-way sensitivity analyses. For patients with Ph-negative ALL in CR1 who decide to undergo transplantation from an alternative donor, elective uBMT from either an 8/8 MUD or a 7/8 MUD is expected to yield a better outcome than immediate CBT. Nonetheless, CBT is a viable option, and improvements to reduce the risk of NRM in CBT may change these results.

Radiation-sparing reduced-intensity unrelated umbilical cord blood transplantation for rare hematological disorders in children

Graft failure is a major pitfall of unrelated umbilical cord blood transplantation (CBT) in children with rare hematological disorders other than acute leukemia, such as acquired and inherited bone marrow failure, myelodysplastic syndrome, juvenile myelomonocytic leukemia, and chronic myeloid leukemia. We developed a less-toxic conditioning regimen for CBT that achieves a higher rate of complete donor chimerism, and retrospectively compared it against two other conditioning regimens for CBT performed at our single institution. The engraftment rate with complete donor chimerism was 100% and 5-year event-free survival (5y-EFS) was 90.9% in patients using our latest regimen (n = 11) of reduced-intensity conditioning (RIC) containing fludarabine (Flu) 180 mg/m², melphalan (MEL) 210 mg/m², and low-dose rabbit anti-thymocyte globulin (LD-rATG) 2.5 mg/kg without irradiation (regimen C). Outcomes were better than in patients (n = 10) treated with previous regimens involving irradiation (5y-EFS 30.0%, p = 0.004): regimen A, consisting of myeloablative conditioning containing cyclophosphamide (CY) and total body irradiation (TBI) with 8-12 Gy, or regimen B, consisting of RIC with Flu, CY, horse ATG, and thoracoabdominal irradiation (TAI) with 6 Gy. In conclusion, Flu/MEL/LD-rATG (regimen C) without TBI/TAI may be preferable as RIC for unrelated CBT in children with rare hematological disorders.

Long-term outcomes following the addition of granulocyte colony-stimulating factor-combined high-dose cytarabine to total body irradiation and cyclophosphamide conditioning in single-unit cord blood transplantation for myeloid malignancies

An intensified myeloablative conditioning regimen, involving the addition of granulocyte colony-stimulating factor (G-CSF)-combined high-dose cytarabine (12 g/m²) to standard total body irradiation and cyclophosphamide, has been performed for adult patients with myeloid malignancies in single-unit cord blood transplantation (CBT) since 1998 in our institute. We update the results of CBT, as the first allogeneic hematopoietic cell transplantation after this conditioning regimen, in 169 patients with a median long-term follow-up of 10.4 years. The median age was 43 years (range, 16 to 59 years). Ninety-four patients (56%) were in non-remission at the time of CBT, and 124 patients (73%) were acute myeloid leukemia. The median cryopreserved cord blood total nucleated cell dose and CD34⁺ cell dose was 2.40 × 10⁷/kg and 0.93 × 10⁵/kg, respectively. The cumulative incidence of neutrophil recovery at 42 days was 94.4% (95% confidence interval [CI]: 88.6-97.3%). Among the whole cohort, 105 patients were still alive at the end of the study period. The cumulative incidences of relapse and non-relapse mortality at 10 years were 26.0% (95% CI: 19.5-33.0%) and 16.9% (95% CI: 11.4-23.4%), respectively. There was an overall survival probability of 62.5% (95% CI: 54.3-69.7%) at 10 years. Higher disease risk index alone significantly affected higher overall mortality (hazard ratio 2.21, P = 0.003) in multivariate analysis. These outcomes demonstrate that G-CSF-combined myeloablative conditioning could have favorable long-term remission rates for adult patients with myeloid malignancies undergoing single-unit CBT.

Total body irradiation-containing conditioning regimens without antithymocyte globulin in adults with aplastic anemia undergoing umbilical cord blood transplantation

Thus far, there have been no large cohort studies on total body irradiation (TBI)-containing conditioning regimens without antithymocyte globulin (ATG) in adults with aplastic anemia (AA) undergoing umbilical cord blood (UCB) transplantation (UCBT). We retrospectively analyzed 115 adults with idiopathic AA undergoing UCBT using TBI-containing reduced-intensity conditioning (RIC) regimens without ATG between 2000 and 2018 on behalf of the Adult Aplastic Anemia Working Group of the Japanese Society for Hematopoietic Cell Transplantation. We then compared transplantation outcomes between a fludarabine (Flu)- and melphalan (Mel)-based regimen (FM) and a Flu- and cyclophosphamide (Cy)-based regimen (FC). The median patient age at UCBT was 41 years. The median total nucleated cell and total CD34⁺ cell doses in a UCB unit at cryopreservation were 2.5 × 10⁷/kg and 0.7 × 10⁵/kg, respectively. The median follow-up period for survivors was 47 months. The cumulative incidence rate of neutrophil engraftment was 76.5%, and the 4-year overall survival (OS) rate was 64.3%. In multivariate analysis, the covariates that were significantly associated with a higher neutrophil engraftment were total CD34⁺ cell dose in an UCB unit (≥ 0.7 × 10⁵/kg; hazard ratio, 0.57, P = 0.01) and total dose of TBI (4 Gy of TBI; hazard ratio, 0.32, P = 0.01). There was no significant difference in the cumulative incidence of neutrophil engraftment and the 4-year OS between the FM and FC groups. In conclusion, TBI-containing RIC regimens without ATG are suitable for adults with AA undergoing UCBT. There were no significant differences in transplantation outcomes between the FM and FC groups.

Hematopoietic Cell Transplantation for Severe Combined Immunodeficiency Patients: a Japanese Retrospective Study

Purpose

Hematopoietic cell transplantation (HCT) is a curative therapy for patients with severe combined immunodeficiency (SCID). Here, we conducted a nationwide study to assess the outcome of SCID patients after HCT in Japan.

Methods

A cohort of 181 SCID patients undergoing their first allogeneic HCT in 1974–2016 was studied by using the Japanese national database (Transplant Registry Unified Management Program, TRUMP).

Results

The 10-year overall survival (OS) of the patients who received HCT in 2006–2016 was 67%. Umbilical cord blood (UCB) transplantation was performed in 81 patients (45%). The outcomes of HCT from HLA-matched UCB (n = 21) and matched sibling donors (n = 22) were comparable, including 10-year OS (91% vs. 91%), neutrophil recovery (cumulative incidence at 30 days, 89% vs. 100%), and platelet recovery (cumulative incidence at 60 days, 89% vs. 100%). Multivariate analysis of the patients who received HCT in 2006–2016 demonstrated that the following factors were associated with poor OS: bacterial or fungal infection at HCT (hazard ratio (HR): 3.8, P = 0.006), cytomegalovirus infection prior to HCT (HR: 9.4, P = 0.03), ≥ 4 months of age at HCT (HR: 25.5, P = 0.009), and mismatched UCB (HR: 19.8, P = 0.01).

Conclusion

We showed the potential of HLA-matched UCB as a donor source with higher priority for SCID patients. We also demonstrated that early age at HCT without active infection is critical for a better prognosis, highlighting the importance of newborn screening for SCID.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10875-021-01112-5.

[Correlation between immune reconstitution and chronic graft-versus-host disease after unrelated cord blood transplantation and sibling peripheral blood stem cell transplantation]

Objective: To explore the relationship between the reconstitution of immune cells in patients with hematological malignancies and the occurrence of chronic graft-versus-host disease (cGVHD) after treatment with unrelated cord blood transplantation (UCBT) and sibling peripheral blood stem cell transplantation (PBSCT) . Methods: A total of 124 patients undergoing allogenic hematopoietic stem cell transplantation (allo-HSCT) in the First Affiliated Hospital of University of Science and Technology of China from March 2018 to August 2019, including 96 patients with UCBT and 28 patients with PBSCT. Peripheral blood immune cells of patients with UCBT and PBSCT were detected at 1, 3, 6, 9, and 12 months after transplantation using flow cytometry, and both UCBT and PBSCT patients were divided into cGVHD and non-cGVHD groups based on whether cGVHD occurred to explore the correlation between the immune cells reconstitution of the two types of transplantation and cGVHD. Results: ①The cumulative incidence of the moderate to severe cGVHD in the UCBT group was significantly lower than that in the PBSCT group[9.38% (95% CI 3.35%-15.02%) vs 28.57% (95% CI 9.72%-43.50%) , P=0.008]; the 2-year cumulative incidence of cGVHD and moderate to severe cGVHD in the UCBT group was lower than that in the PBSCT group[15.60% (95% CI 9.20%-23.60%) vs 32.10% (95% CI 15.80%-49.70%) , P=0.047; 10.40% (95% CI 5.30%-17.50%) vs 28.60% (95% CI 13.30%-46.00%) , P=0.014]. ②The absolute counts of CD4(+)T cells in the UCBT group were higher than those in the PBSCT group at 6, 9, and 12 months after transplantation[59.00 (36.70-89.65) ×10(7)/L vs 31.40 (18.10-44.00) ×10(7)/L, P<0.001; 71.30 (49.60-101.45) ×10(7)/L vs 41.60 (25.82-56.27) ×10(7)/L, P<0.001; 83.00 (50.17-121.55) ×10(7)/L vs 44.85 (31.62-62.10) ×10(7)/L, P<0.001]; the proportions of CD4(+)T cells in the UCBT group were always higher than those in the PBSCT group (P<0.05) . The absolute counts and proportions of B cells in the PBSCT group were higher than those in the UCBT group at the first month after transplantation[0.70 (0.30-1.70) ×10(7)/L vs 0.10 (0-0.30) ×10(7)/L, P<0.001; 0.45% (0.30%-2.20%) vs 0.20% (0.10%-0.40%) , P=0.002]; the absolute counts and proportions of B cells in the UCBT group were higher than those in the PBSCT group at 9 and 12 months after transplantation[53.80 (28.00-103.20) ×10(7)/L vs 23.35 (5.07-35.00) ×10(7)/L, P<0.001; 21.45 (11.80-30.45) % vs 9.00% (3.08%-16.73%) , P<0.001. 66.70 (36.97-98.72) ×10(7)/L vs 20.85 (7.72-39.40) ×10(7)/L, P<0.001; 22.20% (14.93%-29.68%) vs 8.75% (5.80%-18.93%) , P<0.001]. The absolute counts and proportions of regulatory B (Breg) cells in the UCBT group were higher than those in the PBSCT group at 6, 9, and 12 months after transplantation[1.23 (0.38-3.52) ×10(7)/L vs 0.05 (0-0.84) ×10(7)/L, P<0.001; 5.35% (1.90%-12.20%) vs 1.45% (0-7.78%) , P=0.002. 2.25 (1.07-6.71) ×10(7)/L vs 0.12 (0-0.77) ×10(7)/L, P<0.001; 6.25% (2.00%-12.33%) vs 0.80% (0-5.25%) , P<0.001. 3.69 (0.83-8.66) ×10(7)/L vs 0.46 (0-0.93) ×10(7)/L, P<0.001; 6.15% (1.63%-11.75%) vs 1.40% (0.18%-5.85%) , P<0.001].The absolute counts and proportions of CD3(+)T cells, CD8(+)T cells, and Treg cells in the UCBT group were not significantly different from those in the PBSCT group. ③The absolute counts of B cells in the non-cGVHD group of UCBT patients were higher than those in the moderate to severe cGVHD group at 6 and 12 months after transplantation (P=0.038, P=0.043) ; the proportions of B cells in the non-cGVHD group were higher than those in the moderate to severe cGVHD group at 6 months after transplantation (P=0.049) . The absolute counts of Breg cells in the non-cGVHD group of patients with UCBT were higher than those in the moderate to severe cGVHD group at 6, 9, and 12 months after transplantation (P=0.006, P=0.028, P=0.050) ; the proportions of Breg cells in the non-cGVHD group were higher than those in the moderate to severe cGVHD group at 9 months after transplantation (P=0.038) . ④The absolute counts and proportions of B and Breg cells in the non-cGVHD group of patients with PBSCT were not statistically different than those in the moderate to severe cGVHD group. Conclusion: In the process of immune cell reconstitution, the Breg cells in the UCBT group were higher than those in the PBSCT group, and the Breg cells in the non-cGVHD group of the two types of transplantation were always higher than those in the moderate to severe cGVHD group, indicating that Breg cells can reduce the occurrence of cGVHD, revealing the possible reason for the lower incidence of cGVHD in the UCBT group.

Engraftment of Double Cord Blood Transplantation after Nonmyeloablative Conditioning with Escalated Total Body Irradiation Dosing to Facilitate Engraftment in Immunocompetent Patients

To improve accrual to a randomized clinical trial of double unrelated cord blood (dUCB) versus HLA-haploidentical bone marrow (haplo-BM) transplantation, patients with less previous therapy and potentially greater immunocompetence were enrolled. To reduce the risk of graft rejection, patients randomized to receive dUCB received a higher dose of total body irradiation (TBI) (300 cGy versus 200 cGy). In this study, we investigated whether the inclusion of recipients of 300 cGy TBI influenced the trial outcomes. This was a secondary analysis of dUCB recipients, 161 who received TBI 200 cGy and 18 who received TBI 300 cGy. Fine and Gray regression was used to evaluate the effect of TBI dose on relapse and nonrelapse mortality (NRM). Cox regression was used for evaluation of neutrophil engraftment and overall survival. Patient characteristics were similar in the 2 TBI dose subgroups. The probability of neutrophil engraftment was 100% for patients who received TBI 300 cGy versus 91% (95% confidence interval, 86% to 95%) for those who received TBI 200 cGy (P = .64), which was similar after regression analysis adjusting for age, total infused nucleated cell dose, HLA matching to the patient, and comorbidity score. We also investigated whether the lower survival probability and higher cumulative incidence of NRM observed in the dUCB arm of BMT CTN 1101 could be influenced by the TBI 300 cGy patient subset. There was no significant difference in the 1-year incidences of NRM and relapse or in 1-year survival, even after adjustment in multivariate analysis. Patients in BMT CTN 1101 who received TBI 300 cGy and 200 cGy had similar engraftment and early mortality. We conclude that inclusion of a modified regimen for dUCB transplantation had no demonstrable influence on this large randomized trial.

[Optimal selection of alternative donors for allogeneic hematopoietic stem cell transplantation]

A human leukocyte antigen (HLA)-matched related donor is considered as the first donor candidate in case of allogenic hematopoietic stem cell transplantation (allo-HSCT). Given the declining birthrate and aging population in Japan, the number of sibling donors is also decreasing. Hence, candidates other than HLA-matched siblings, named "alternative donors," have attracted increasing attention. Improved graft-versus-host disease (GvHD) prophylaxis with posttransplant cyclophosphamide or pretransplant antithymocyte globulin represented a major breakthrough in allo-HSCT with alternative donors by overcoming the barriers of HLA mismatch. In addition, there have been improved outcomes of unrelated cord blood transplantation, owing to better unit selection along with improved GvHD prophylaxis and supporting strategies. These changes have expanded the range of donor options and consequently, increased donor availability at the critical moment for allo-HSCT. The next challenge that warrants further investigation is the development of personalized strategies to select the best donor from the available multiple options according to the status of each patient.

Combined impact of HLA-allele matching and the CD34-positive cell dose on optimal unit selection for single-unit cord blood transplantation in adults

The combined effects of HLA-allele matching at six-loci (HLA-A, -B, -C, -DRB1, -DQB1, and -DPB1) and CD34⁺ cell dose on clinical outcomes were analyzed in 1,226 adult cases with single-unit unrelated cord blood transplantation. In the six-loci analysis, low HLA-allele matches did not significantly increase the overall mortality compared to higher matches, whereas in the five-loci analysis excluding HLA-DPB1, they caused a higher overall mortality (HR 1.42, p = .002), possibly due to the graft-versus-leukemia effect of HLA-DPB1 mismatches. A lower CD34⁺ cell dose (<.50 × 10⁵/kg) resulted in higher mortality and lower engraftment; these inferior outcomes were offset by high HLA-allele matches (7-10/10 match), while the inferior outcomes of low HLA-allele matches were improved by increasing the CD34⁺ cell dose. Consideration of the combined effects of the CD34⁺ cell dose and HLA matching may expand the options for transplantable units when HLA matching or the CD34⁺ cell dose is inadequate.

Prognostic impact of the dosage of methotrexate combined with tacrolimus for graft-versus-host disease prophylaxis after cord blood transplantation

The optimal dosage of methotrexate (MTX) for graft-versus-host disease (GVHD) prophylaxis after cord blood transplantation (CBT) has not been well elucidated. Therefore, we conducted a retrospective study comparing a mini-MTX group (5 mg/m² on day 1, 3 and 6) to a short-MTX group (10 mg/m² on day 1 and 7 mg/m² on day 3 and 6) after CBT. Sixty-three patients were classified as the mini-MTX group and 20 as the short-MTX group. The median time and cumulative incidence of neutrophil engraftment did not vary between the two groups. The cumulative incidence of grade 2-4 and grade 3-4 acute GVHD was similar in both groups. Overall survival in the mini-MTX group was significantly lower than in the short-MTX group (46.9% vs. 88.7% at 1 year, p < 0.01), contributing to higher non-relapse mortality (NRM) in the mini-MTX group (32.0% vs. 5.0% at 1 year, p = 0.02). In multivariate analysis, the mini-MTX regimen was the most powerful prognostic factor for OS (hazard ratio 4.11; p = 0.03). Although the reduced dosage of MTX had no effect on neutrophil engraftment, increased NRM due to higher incidence of infection, graft failure, and severe acute GVHD resulted in a lower survival rate in the mini-MTX group after CBT.

Successful Cord Blood Transplantation for Idiopathic CD4+ Lymphocytopenia

Idiopathic CD4+ lymphocytopenia (ICL) is the depletion of CD4+ lymphocytes to <300 cells/mm3 without human immunodeficiency virus infection or other causes of lymphocytopenia. ICL causes fatal infections; its etiology remains unclear and it lacks consensus regarding therapeutic options. We report the first patient with ICL who had a successful clinical course following a cord blood transplant (CBT). A 45-year-old woman was diagnosed with ICL and underwent partial hepatectomy for an abscess caused by the Mycobacterium avium complex. No specific gene alterations were detected through next generation sequencing-based evaluation. Following a reduced-intensity conditioning (RIC) regimen consisting of fludarabine, busulfan, and 4 Gy total body irradiation, a single-unit CBT was performed. Neutrophils were engrafted on day +14. CD4+ lymphocyte counts increased to over 300 cells/mm3 on day +436. After 75 months, she was alive without any sequelae. CBT with an RIC regimen could be a curable treatment option for ICL.

Elevation of HHV-6 viral load mimicking HHV-6 reactivation after second umbilical cord blood transplantation in chromosomally integrated human herpesvirus-6

Human herpesvirus-6 (HHV-6) reactivation is an important complication in patients receiving umbilical cord blood transplantation (CBT). Chromosomally integrated human herpesvirus-6 (ciHHV-6) is a condition in which the complete HHV-6 genome is integrated into the host germline genome and is transmitted in a Mendelian manner. The influence of ciHHV-6 in recipients or donors in cases of CBT is unknown. We report the first case with ciHHV-6 that received CBT twice for acute lymphoblastic T-cell leukemia. HHV-6 DNA in peripheral blood leukocytes (PBLs) was examined over time through two CBTs. After the first CBT, the HHV-6 viral load was significantly reduced by conversion to PBLs derived from the first donor. During the second CBT, an increase in HHV-6 DNA in PBLs and plasma were observed. However, HHV-6 mRNA was not detected in either the sample before 2nd CBT or at the time of HHV-6 DNA elevation. It is considered that the HHV-6 DNA detected in PBLs and plasma samples might be the HHV-6 genome released due to tissue damage. This case suggests that physicians should be aware of HHV-6 DNA variability during allogeneic hematopoietic stem cell transplantation in ciHHV-6 patients.

Kinetics of IgG subclasses and their effects on the incidence of infection after allogeneic hematopoietic stem cell transplantation

BACKGROUND

The impact of the reconstitution of IgG subclasses after allogeneic hematopoietic cell transplantation (allo-HCT) on the outcomes is unclear.

METHODS

We investigated the effects of stem cell source on the levels of serum IgG subclasses and their influence on the infection risk and prognosis. The levels of serum IgG, IgG2 and IgG4 were measured chronologically in 100 patients who underwent allo-HCT at our institute.

RESULTS

The median levels of serum IgG, IgA and IgM and the number of total B-cells were determined up to one year after allo-HCT. The serum IgG2 levels decreased within one year. A multiple linear regression analysis identified lymphoid malignancy, cord blood, and days after allo-HCT as significant risk factors for low serum IgG2 levels. There were no significant differences in the level of IgG or IgG2 at 90 days after allo-HCT between the late bacterial infection group (≥90 days following allo-HCT) and the control group (P = 0.34 and 0.45, respectively). There was no significant impact of the IgG, IgG2 or IgG4 levels on the survival or non-relapse mortality.

CONCLUSION

The results suggest that cord blood transplantation might affect humoral immune reconstitution, including the IgG2 level, after allo-HCT.

Allogeneic hematopoietic cell transplantation with cord blood versus mismatched unrelated donor with post-transplant cyclophosphamide in acute myeloid leukemia

BACKGROUND

Allogeneic hematopoietic cell transplantation (allo-HCT) using a mismatched unrelated donor (MMUD) and cord blood transplantation (CBT) are valid alternatives for patients without a fully human leukocyte antigen (HLA)-matched donor. Here, we compared the allo-HCT outcomes of CBT versus single-allele-mismatched MMUD allo-HCT with post-transplant cyclophosphamide (PTCy) in acute myeloid leukemia.

METHODS

Patients who underwent a first CBT without PTCy (N = 902) or allo-HCT from a (HLA 9/10) MMUD with PTCy (N = 280) were included in the study. A multivariate regression analysis was performed for the whole population. A matched-pair analysis was carried out by propensity score-based 1:1 matching of patients (177 pairs) with known cytogenetic risk.

RESULTS

The incidence of grade II-IV and grade III-IV acute graft-versus-host disease (GVHD) at 6 months was 36% versus 32% (p = 0.07) and 15% versus 11% (p = 0.16) for CBT and MMUD cohorts, respectively. CBT was associated with a higher incidence of graft failure (11% vs. 4%, p < 0.01) and higher 2-year non-relapse mortality (NRM) (30% vs. 16%, p < 0.01) compared to MMUD. In the multivariate analysis, CBT was associated with a higher risk of, NRM (HR = 2.09, 95% CI 1.46-2.99, p < 0.0001), and relapse (HR = 1.35, 95% CI 1-1.83, p = 0.05), which resulted in worse leukemia-free survival (LFS) (HR = 1.68, 95% CI 1.34-2.12, p < 0.0001), overall survival (OS) (HR = 1.7, 95% CI 1.33-2.17, p < 0.0001), and GVHD-free, relapse-free survival (GRFS) (HR = 1.49, 95% CI 1.21-1.83, p < 0.0001) compared to MMUD. The risk of grade II-IV acute GVHD (p = 0.052) and chronic GVHD (p = 0.69) did not differ significantly between the cohorts. These results were confirmed in a matched-pair analysis.

CONCLUSIONS

CBT was associated with lower LFS, OS, and GRFS due to higher NRM, compared to MMUD allo-HCT with PTCy. In the absence of a fully matched donor, 9/10 MMUD with PTCy may be preferred over CBT.

Outcomes of Adolescents and Young Adults Compared with Children with Acute Leukemia after Single-Unit Unrelated Cord Blood Transplantation Using Myeloablative Conditioning without Antithymocyte Globulin

BACKGROUND

Although the use of cord blood transplantation (CBT) is becoming more frequent in acute leukemia, considering the relationship between the low stem cell dose and graft failure, whether use of CBT for adolescents and young adults (AYAs) is appropriate remains uncertain.

METHODS

A retrospective registry-based analysis of clinical outcomes and immune reconstitution was conducted for 105 AYAs and 187 children with acute leukemia who underwent single-unit CBT using myeloablative conditioning (MAC) without antithymocyte globulin (ATG).

RESULTS

Outcomes were similar between AYAs and children, except for nonrelapse mortality (NRM) and recovery rates of neutrophils and platelets. The 30-day cumulative incidence of neutrophil engraftment was similar between AYAs and children, but children had faster rates of neutrophil and platelet recovery than AYAs. The median time to neutrophil engraftment was earlier in children than in AYAs (AYAs, 19 days, 95% confidence interval [CI] 17.3-21.7; children, 16 days, 95% CI 13.1-19.5, p = 0.00003). The incidence of platelet recovery on day 120 was higher in children than in AYAs (AYAs, 80%, 95% CI 71-81%; children, 88%, 95% CI 82-92%, p = 0.037). CD34+ cell dose was the only independent factor influencing both neutrophil and platelet recovery. The cumulative incidence of NRM at 2 years was higher among AYAs than among children (AYAs, 27.5%, 95% CI 20-37%; children, 15%, 95% CI 10-21%, p = 0.008). Conditioning regimen was an independent factor influencing NRM. With respect to immune reconstitution, natural killer cell counts quickly recovered to normal levels 1-month post-CBT in both children and AYAs. CD8+ T-cell counts were higher in children than in AYAs at 1 and 3 months post-CBT. CD4+ T-cell counts were similar in both children and AYAs after CBT.

CONCLUSION

AYAs with acute leukemia have outcomes of single-unit CBT using MAC without ATG that are as good as those of children. Thus, single-unit CBT using modified MAC without ATG is an acceptable choice for both AYAs and children who do not have a suitable donor.

Post-transplant food anaphylaxis in an adult cord blood transplant recipient (Ms. No. IJHM-D-20-01037R1)

Transplant acquired food allergy (TAFA) is a well-known complication following pediatric liver transplantation, but post-cord blood transplantation (post-CBT) TAFA has rarely been reported. Here, we describe a case of new-onset food anaphylaxis after CBT in an adult patient that demonstrates that post-CBT allergen-challenge is not a risk for long-term allergic sensitization even in adult recipients. The patient was a 39-year-old Japanese man with aggressive NK cell leukemia. He had no previous history of allergies. After receiving CBT, the patient had an unbalanced diet with high preference for bread, bananas, miso-soup, cow's milk, cheese, egg, sesame and buckwheat soba noodles, and experienced repeated diarrhea. Six months later, he developed symptoms such as vomiting, epigastric pain, diarrhea, high fever and hypotension. The condition was initially diagnosed as enterocolitis, but symptoms recurred after consumption of buckwheat. Anaphylaxis induced by buckwheat was confirmed with serum radioallergosorbent tests (RAST), showing allergen-specific IgE for buckwheat (greater than 100 U/mL, Class 6) and egg ovomucoid (Class 4). Nineteen months after a buckwheat and egg-free diet, serum RAST for buckwheat and egg significantly improved. As a result, the patient acquired a tolerance and was able to consume buckwheat and egg without allergic symptoms.

Feasibility of an intensified myeloablative conditioning regimen consisting of busulfan, fludarabine, cytarabine, and total body irradiation before single cord blood transplantation in elderly patients

The optimal conditioning regimen for stem cell transplantation in elderly patients remains to be established. We developed a novel preparative regimen using fludarabine 180 mg/m², intravenous busulfan 12.8 mg/m², cytarabine 8 g/m², and 4-Gy total body irradiation before cord blood transplantation (CBT) in patients older than 55 years with various hematological malignancies. All but one patient received graft-versus-host disease (GVHD) prophylaxis consisting of cyclosporine (CsA) and short-term methotrexate (sMTX). Thirty-three patients were included in this study, with a median age of 64 years (range 56-70). The disease risk index was high or very high in 67% of patients, and 73% had a disease status other than complete remission. The probabilities of overall survival and disease-free survival at 3 years were 60 and 57%, respectively. The cumulative incidences of relapse and non-relapse mortality at 3 years were 18 and 25%, respectively. Regimen-related toxicities were generally tolerable. Disease-free survivors (n = 20) stopped immunosuppressants at a median of 7.4 months (range 2.6-25.0), in all cases by the time of the last follow-up. In conclusion, this highly myeloablative conditioning regimen resulted in a high probability of disease-free, GVHD-free, immunosuppressant-free survival after single CBT.(190 words).

Favorable Outcomes after Single Cord Blood Transplantation for Patients with High-Risk Hematologic Diseases: A Single-Institute Retrospective Analysis

The donor selection algorithm for cord blood (CB) with regards to matched related and unrelated donors has not been fully investigated. To assess the potential of CB transplantation (CBT) in patients with hematologic malignancies, especially for high-risk patients, we performed a single-institute retrospective analysis and compared the clinical outcomes of CBT with those of HLA-matched sibling and unrelated donor transplantation. We included 394 patients aged 16 years and older with hematologic diseases who received their first allogeneic hematopoietic cell transplantation between 1990 and 2018 at Kyoto University Hospital. These included 394 recipients of single unrelated cord blood units (UCB, n = 108), HLA-matched sibling donors (MSDs, n = 143), or HLA-matched unrelated donors (MUDs, n = 143). There was no significant difference in relapse-free survival (RFS) between UCB, MSD, and MUD recipients (P = .975). However, we found a significant interaction between transplant year and CBT outcomes (P = .010), with significantly better outcomes observed in the more recent years. Furthermore, we found that CBT showed better RFS than matched donor transplantation (hazard ratio [HR], 0.50; 95% confidence interval [CI], 0.30 to 0.84). This impact was more prominent in high-risk patients (HR, 0.35; 95% CI, 0.16 to 0.77), with lower relapse rates (HR, 0.25; 95% CI, 0.11 to 0.54), and comparable non-relapse mortality (NRM) compared to matched donor transplantation. Extensive chronic graft-versus-host disease was less frequently observed in CBT (HR, 0.58; 95% CI, 0.26 to 1.28). CBT associated with favorable outcomes, particularly in high-risk patients, with good RFS and low relapse rates without an increase in NRM in the single-institute study. Although the findings should be externally validated, CBT might serve as a reasonable donor choice, particularly in high-risk patients.

Single cord blood transplantation for acute myeloid leukemia patients aged 60 years or older: a retrospective study in Japan

The availability of alternative donor sources could allow elderly patients to receive allogeneic hematopoietic cell transplantation (HCT). We retrospectively evaluated the outcomes of single-unit cord blood transplantation (CBT) in 1577 patients aged ≥60 years with acute myeloid leukemia (AML) in Japan between 2002 and 2017. In total, 990 (63%) patients were not in complete remission (CR) at the time of CBT. A myeloablative conditioning regimen (52%) and calcineurin inhibitor (CI) + mycophenolate mofetil (MMF)-based graft-versus-host disease (GVHD) prophylaxis (45%) were more commonly used. With a median follow-up for survivors of 31 months, the probability of overall survival and the cumulative incidence of leukemia-related mortality at 3 years was 31% and 29%, respectively. The cumulative incidence of non-relapse mortality (NRM) at 100 days and 3 years were 24% and 41%, respectively. The cumulative incidences of grade II-IV and grade III-IV acute GVHD at 100 days and extensive chronic GVHD at 2 years were 44%, 16%, and 14%, respectively. The cumulative incidence of neutrophil engraftment was 80% at 42 days. Results of multivariate analysis indicated that the following factors were significantly associated with higher overall mortality: performance status ≥1, hematopoietic cell transplantation-specific comorbidity index ≥3, adverse cytogenetics, extramedullary disease at diagnosis, and non-CR status at CBT. By contrast, female sex, HLA disparities ≥2, mycophenolate mofetil-based GVHD prophylaxis, and recent CBT were significantly associated with lower overall mortality. In conclusion, single CBT offers a curative option for AML patients aged ≥60 years with careful patient selection.