Effect of race on outcomes after allogeneic hematopoietic cell transplantation for severe aplastic anemia

Immunosuppression-Free Status at 1 Year after Haploidentical Hematopoietic Cell Transplantation with Post-Transplantation Cyclophosphamide

The development of chronic graft-versus-host disease (GVHD) in 1-year survivors after matched related or unrelated hematopoietic cell transplantation was shown to be associated with higher nonrelapse mortality (NRM) and worse overall survival (OS). The impact of chronic GVHD requiring immunosuppression (IS) for recipients of haploidentical transplantation (HIDT) with post-transplantation cyclophosphamide (PTCy) who have survived to 1 year post-transplantation has not been studied previously and was investigated for this analysis. A total of 322 adult patients who underwent HIDT at our center were included in this study. The effect of IS-free status on post-transplantation outcomes was assessed. The median follow-up for survivors was 63.9 months (range, 18.3 to 165 months). A total of 163 patients (65%) were IS-free at 1 year post-HIDT. Baseline characteristics of this group were similar to those of patients still requiring IS, except for higher percentages of female donor-male recipient pairs (28% versus 15%; P =.03) and female donors (48% versus 30%; P =.008). Logistic regression to identify patients more likely to be on IS at 1 year post-HIDT identified the use of a female donor as a significant risk factor (odds ratio, 2.11; P = .009). In a Cox regression analysis, patients requiring IS at 1 year post-transplantation had higher NRM (hazard ratio [HR], 4.18; 95% confidence interval [CI], 1.80 to 6.72; P < .001) and showed a trend toward worse disease-free survival (DFS) (HR, 1.59; 95% CI, .95 to 2.66; P =.08), with no impact on OS (HR, 1.44; 95% CI, .90 to 2.31; P = .13) or relapse (HR, .77; 95% CI, .37 to 1.61; P = .49). These results indicate that use of a female donor is a significant risk factor for requiring IS at 1 year post-HIDT. Additionally, chronic GVHD requiring IS at 1-year post-HIDT no significant effect on relapse but is associated with higher NRM and a trend toward worse DFS.

Utilization and outcome disparities in allogeneic hematopoietic stem cell transplant in the United States

Allogeneic hematopoietic stem cell transplant (allo-HSCT) is increasingly being used in the United States (US) and across the world as a curative therapeutic option for patients with certain high-risk hematologic malignancies and non-malignant diseases. However, racial and ethnic disparities in utilization of the procedure and in outcome following transplant remain major problems. Racial and ethnic minority patients are consistently under-represented in the proportion of patients who undergo allo-HSCT in the US. The transplant outcomes in these patients are also inferior. The interrelated driving forces responsible for the differences in the utilization and transplant outcome of the medical intervention are socioeconomic status, complexity of the procedure, geographical barriers, and the results of differences in the genetics and comorbidities across different races. Bridging the disparity gaps is important not only to provide equity and inclusion in the utilization of this potentially life-saving procedure but also in ensuring that minority groups are well represented for research studies about allo-HSCT. This is required to determine interventions that may be more efficacious in particular racial and ethnic groups. Various strategies at the Federal, State, and Program levels have been designed to bridge the disparity gaps with varying successes. In this review paper, we will examine the disparities and discuss the strategies currently available to address the utilization and outcome gaps between patients of different races in the US.

Comparative Analysis of Allogeneic Bone Marrow Transplantation Outcomes Between Japanese and Non-Japanese Populations

BACKGROUND

As the Japanese population may have less genetic diversity than other ethnic groups, treatment outcomes may be affected when allogeneic hematopoietic cell transplantation is performed in other races. However, evidence explaining the effect of racial differences is limited.

METHODS

We used the Japanese National Database to examine the outcomes of first allogeneic bone marrow transplantations (BMTs) performed between Japanese and non-Japanese patients from 1996 to 2021. We performed propensity score matching using sex, age group, underlying disease group, HLA mismatch, conditioning regimen intensity, and BMT implementation age to select Japanese-to-Japanese BMT patients as the controls.

RESULTS

The numbers of non-Japanese-to-Japanese and Japanese-to-non-Japanese BMT cases included in the analysis were 48 and 75, respectively, and the following outcomes were compared: overall survival, non-relapse mortality, acute graft-vs-host disease (GVHD) ≥ grade II, chronic GVHD, and engraftment of neutrophils and platelets. Most parameters did not differ when comparing BMTs according to ethnicity; only platelet engraftment was delayed in Japanese-to-non-Japanese BMT but not in non-Japanese-to-Japanese BMT.

CONCLUSIONS

The results of this study suggested that BMT performed in Japanese and non-Japanese patients has little effect on treatment outcomes. The results of this study may be useful for donor selection in Japan, where internationalization has progressed in recent years.

Racial disparities in hematopoietic stem cell transplant: a systematic review of the literature

Background

Hematopoietic stem cell transplant (HSCT) is an expensive and complex treatment regimen that can be curative in many diseases of the bone marrow, including malignant and non-malignant conditions. The introduction of the Affordable Care Act increased access to potential candidates and removed or reduced many barriers previously identified in the literature, however, racial disparities continue to persist. As HSCT expands its utilization and indications, there is a continued need to understand the multifactorial barriers which lead to inequalities in transplant referral, utilization, and survival. The objective of this systematic review is to summarize these racial disparities, expand the current understanding of the literature, and determine whether the increases in insurance status from Medicaid expansion have played a role in HSCT utilization and survival rates by race.

Methods

We explored studies based on retrospective reviews, literature reviews, and focus groups with the key-terms of 'race', 'hematopoietic stem cell transplant', and 'disparities'. The included studies were extracted from Cochrane and Medline databases. After screening for relevancy to research aims and objectives, 10 articles were utilized for background information and discussion, while 30 articles were categorized into main groups of outcomes, chiefly, (I) access/referral to transplant and (II) survival.

Results

Eight of the eleven retrospective reviews found substantial variation in access to HSCT by ethnic minorities (Black, Hispanic, or Asian) when compared to their Caucasian counterparts. Thirteen of the fourteen publications found racial disparities in either overall survival, progression free survival, treatment related mortality, relapse, or combinations of these outcomes. The majority of the studies evaluated African American patients with six of eight studies showing significantly elevated mortality compared to Caucasian patients.

Discussion

Substantial variation exists in access to HSCT, particularly in black patients. Having less generous insurance coverage was previously hypothesized to reduce the likelihood of HSCT utilization. Studies performed after full implementation of the Affordable Care Act continue to show poorer survival among ethnic minorities, particularly black patients, despite this increased coverage. Perceived racial bias and health-related stigma, as well as physician decisions and delay in referral process are likely contributing factors.

Race as a factor in donor selection and survival of children with hematologic malignancies undergoing hematopoietic stem cell transplant in Florida

BACKGROUND

Previous studies have explored posthematopoietic cell transplant (HCT) outcomes by race in adults; however, pediatric data addressing this topic are scarce.

PROCEDURE

This retrospective registry study included 238 White (W) and 57 Black (B) children with hematologic malignancies (HM) receiving first allogeneic HCT between 2010 and 2019 at one of the five Florida pediatric HCT centers.

RESULTS

We found no differences between W and B children in transplant characteristics, other than donor type. There was a significant difference in use of human leukocyte antigen (HLA)-mismatched donors (HLA-MMD) (53% W, 71% B, p = .01). When comparing HLA-MMD use to fully HLA-matched donors, B had relative risk (RR) of 1.47 (95% CI 0.7-3) of receiving a mismatched unrelated donor (MMUD), RR of 2.34 (95% CI 1.2-4.4) of receiving a mismatched related donor (MMRD), and RR of 1.9 (95% CI 0.99-3.6) of receiving a mismatched cord blood donor (MMCBD) HCT, respectively. There was no significant difference in the incidence of aGVHD (48% W, 35% B), p = .1, or cGVHD (19% W, 28% B, p = .1), or primary cause of death. Overall 24-month survival was 61% (95% CI 55%-68%) for W, and 60% (95% CI 48-75) for B children, log-rank p = .7. While HLA matching improved survival in W children, the number of B children receiving HLA-matched HCT was too small to identify the impact of HLA matching on survival.

CONCLUSIONS

In this contemporary cohort of children with HM, we found that B children were more likely to receive HLA-MMD transplants, but this did not adversely affect survival or GVHD rates.

Parental limited English proficiency in pediatric stem cell transplantation: Clinical impact and health care utilization

BACKGROUND

Limited English proficiency (LEP) is associated with adverse clinical outcomes. The clinical impact of LEP in hematopoietic stem cell transplant (HSCT) has not been studied. The objectives of this study were to compare HSCT outcomes and health care utilization of Hispanic pediatric patients with and without parental LEP.

METHODS

We conducted a retrospective review of Hispanic/Latino pediatric patients receiving HSCT at a single institution. Families were identified as LEP or English proficient (EP) based on clinicians' notes, social work documentation, or the signature of a Spanish interpreter on treatment consents.

RESULTS

A total of 83 Hispanic/Latino patients were identified with 53 (65.1%) having parental LEP. More patients in the LEP group had a documented financial burden at pretransplant psychosocial evaluation (72.2% vs. 41.4%, p = .009). LEP patients were more likely to have health insurance coverage through government-sponsored Medicaid (76.9% vs. 27.6%, p < .001). LEP patients were hospitalized on average 13 days longer than EP patients, and LEP patients were more likely to have pretransplant cytomegalovirus (CMV) reactivity (67.3%) than EP patients (p = .001). Overall survival was lower in LEP than EP, but was not statistically significant (p = .193). Multivariable Cox modeling suggested a potentially higher risk of death in LEP versus EP (hazard ratio = 1.56, 95% CI: 0.38, 6.23).

CONCLUSIONS

Parental LEP in HSCT is associated with prolonged hospitalization and pretransplant CMV reactivity. These factors are associated with posttransplant complications and death. Our results suggest parental LEP is a risk factor for poor HSCT outcomes. Further study is warranted in a larger cohort.

Abatacept is effective as GVHD prophylaxis in unrelated donor stem cell transplantation for children with severe sickle cell disease

We report results of a phase 1 multicenter stem cell transplantation (SCT) trial from HLA-matched (n = 7) or one-antigen-mismatched (n = 7) unrelated donors (URD) using bone marrow or cord blood as stem cell source, following reduced-intensity conditioning (RIC) in severe sickle cell disease (SCD). Conditioning included distal alemtuzumab, fludarabine, and melphalan (matched donors), with thiotepa (mismatched donors). Abatacept, a selective inhibitor of T cell costimulation, was added to tacrolimus and methotrexate as graft-versus-host disease (GVHD) prophylaxis to offset GVHD risks, and was administered for longer duration in bone marrow recipients than in cord blood recipients because of increased incidence of chronic GVHD with bone marrow. Median age at transplant was 13 years (range, 7-21 years). The incidence of grades II to IV and grades III to IV acute GVHD at day +100 was 28.6% and 7%, respectively. One-year incidence of chronic GVHD was 57% and mild/limited in all but 1 patient who received abatacept for a longer duration. Only 1 patient developed reversible posterior encephalopathy syndrome and recovered. With a median follow-up of 1.6 years (range, 1-5.5 years), the 2-year overall and disease-free survival was 100% and 92.9%, respectively. The encouraging results from the phase 1 portion of this RIC SCT trial, despite risk factors such as older age, URD, and HLA-mismatch, support further evaluation of URD SCT in clinical trial settings. The phase 2 portion of the trial is in progress. This trial was registered at www.clinicaltrials.gov as NCT03128996.

An Examination of Cytomegalovirus, Socioeconomic Status, Race, and Ethnicity on Outcomes after Haploidentical Hematopoietic Transplantation

Previous analyses of the effects of race and socioeconomic status (SES) on outcomes after hematopoietic stem cell transplantation (HSCT) have suggested that minority populations and those in disadvantaged groups have inferior outcomes. However, the results of these studies have been inconsistent, potentially due to a multitude of factors, both medical and nonmedical, that have confounded results. In haploidentical (HI) HSCT, an expanding approach with the potential to enfranchise more minority patients, data on the effect of race and SES on outcomes are very limited. To identify and potentially correct factors that negatively impact outcomes after HI HSCT in disadvantaged groups at our institution, we performed a retrospective, multivariable analysis of the impact of race and SES as single and combined variables on HI HSCT outcomes of relapse, transplantation-related mortality, acute and chronic graft-versus-host disease (GVHD), and overall survival (OS). In addition to controlling for race and SES, all patients had HI donors and were treated with the same 2-step approach, with consistent T cell dosing and GVHD prophylaxis to further reduce the impact of confounders in this complex area. The study cohort of 239 patients was 71% Caucasian, 19.7% African American, 4.6% Hispanic, and 4.2% Asian. The majority of minority patients were in areas of higher deprivation (P = .001) and had the highest incidence of cytomegalovirus (CMV) seropositivity (P = .001) and the lowest likelihood of possessing a CMV immunodominant (IMD) allele (P = .001), which was previously associated with an OS benefit. Positive CMV serostatus was highly linked to post-transplantation CMV reactivation (P = .001) which was associated with higher relapse rates (hazard ratio [HR], 1.56; 95% confidence interval [CI], 1.06 to 2.30; P = .026), higher TRM (HR, 2.10; 95% CI, 1.09 to 4.05; P = .027), and lower OS (HR, 1.77; 95% CI, 1.18 to 2.65; P = .006). The lack of a CMV IMD allele largely replicated the results of CMV reactivation on HSCT results. Although race and SES did not directly correlate with either OS or relapse incidence, non-Caucasians in a more disadvantaged group had a higher incidence of chronic GVHD (HR, 2.55; 95% CI, 1.08 to 6.01; P = .033) compared with Caucasians and minorities in less disadvantaged groups. Regardless of SES, minorities had a lower incidence of acute GVHD than Caucasians in a more advantaged SES group (HR, 0.52; 95% CI, 0.30 to 0.90; P = .020). The primary finding of this study is that CMV reactivation was the major driver of mortality after HI HSCT. CMV reactivation may have be associated with poor HSCT outcomes in HI HSCT recipients in disadvantaged areas, most of whom were minorities. The data suggest that the prevention of post-transplantation CMV reactivation possibly could have a major impact on HI HSCT outcomes, especially in minority recipients. The finding of different GVHD manifestations between races are intriguing and merits further study.

Comparison of characteristics and outcomes of late acute and NIH chronic GVHD between Japanese and white patients

Although differences in the incidence of chronic graft-versus-host disease (GVHD) across the races have been suggested, these have not been systematically investigated. This study compared the incidence, sites, severity, and outcomes of late acute GVHD and chronic GVHD according to National Institutes of Health (NIH) consensus criteria between Japanese (n = 413) and white (n = 708) patients after first allogeneic hematopoietic cell transplantation. Analysis was stratified according to bone marrow transplantation (BMT) or peripheral blood stem cell transplantation (PBSCT). Japanese patients, compared with white patients, had a similar incidence of late acute GVHD (BMT, 19% vs 16%; PBSCT, 19% vs 16%) but experienced more frequent liver late acute GVHD as defined by transaminase elevation (BMT, 79% vs 8%; PBSCT, 92% vs 33%) and less frequent gastrointestinal late acute GVHD (BMT, 11% vs 58%; PBSCT, 20% vs 68%). Japanese patients were more likely to discontinue systemic immunosuppression after late acute GVHD than white patients (hazard ratio, 3.68; 95% confidence interval, 1.96-6.94; P < .001). Japanese patients, compared with white patients, had a lower incidence of chronic GVHD (BMT, 15% vs 30% [P = .002]; PBSCT, 37% vs 45% [P < .001]) and experienced more frequent chronic GVHD of the mouth, eyes, and liver and less frequent gastrointestinal chronic GVHD. The duration of immunosuppressive treatment of NIH chronic GVHD was similar between the races. These differences could not be entirely attributed to practice variation between the centers. This study shows that the incidence, affected sites, severity, and clinical outcomes of late acute GVHD and NIH chronic GVHD differ between Japanese and white patients.

Patient features and survival of pediatric aplastic anemia in the USA: a large institution experience

BACKGROUND

We performed the first epidemiologic investigation to examine association of demographics and clinical characteristics at diagnosis, as well as health care expense coverage, with survival of US children with aplastic anemia (AA).

METHODS

We obtained electronic medical record data of 1140 children aged 0-19 years diagnosed with AA followed at a pediatric health system between 2004 and 2014. Kaplan-Meier curve and Cox proportional hazards regressions were used.

RESULTS

Self-pay patients had a mortality risk five times higher than that of those insured by publicly funded insurance (hazards ratio, 95% CI: 6.0, 3.7-9.8). Other features associated with higher mortality risk include pancytopenia (hazards ratio, referent: 4.2, constitutional AA); underweight (2.0, normal-weight); platelet count <50 × 109/l (1.3, ≥50 × 109/l); male sex (1.3, female); and ages at diagnosis 6-11, 11-16 and 16-19 years (1.6, 1.9, 2.3, 1-3 years), respectively.

CONCLUSIONS

Self-pay was the strongest prognostic factor for pediatric AA mortality. Older age, pancytopenia, underweight, male sex and lower platelet count were also associated with increased risk of mortality. These findings may be useful for providers, researchers and policymakers to ensure effective health care delivery to this population and to motivate future etiologic research and establishment of a surveillance registry.

Principles of alemtuzumab immunoablation in hematopoietic cell transplantation for non-malignant diseases in children: A review

Alemtuzumab is a humanized mAb targeted to CD52. Alemtuzumab is highly immunosuppressive with the ability to deplete T and B cells (in addition to other immune cell lines). A growing understanding of the PKs, dosing, and timing of administration of alemtuzumab has allowed for the study of its use as a conditioning agent for allogeneic HCT. The highly immunosuppressive properties of the drug are particularly appealing in the setting of non-malignant HCT, where GVHD provides no clinical benefit and relapse of malignancy is not applicable. In addition, the degree of immune suppression achieved with alemtuzumab has allowed for a reduction in the intensity of myeloablative cytotoxic agents included in some HCT conditioning regimens, allowing for fewer acute and late toxicities. This review paper will provide a comprehensive summary of the mechanism of action, PKs, dosing, and timing of alemtuzumab, a brief description of its use in various allogeneic HCT protocols for non-malignant conditions and a summary of the data regarding its use for GVHD therapy. The goal of this review was to provide an understanding as to how alemtuzumab might be safely incorporated into HCT conditioning regimens for children with non-malignant disease, allowing for expanded access to curative HCT therapy.

A trial of unrelated donor marrow transplantation for children with severe sickle cell disease

Children with sickle cell disease experience organ damage, impaired quality of life, and premature mortality. Allogeneic bone marrow transplant from an HLA-matched sibling can halt disease progression but is limited by donor availability. A Blood and Marrow Transplant Clinical Trials Network (BMT CTN) phase 2 trial conducted from 2008 to 2014 enrolled 30 children aged 4 to 19 years; 29 were eligible for evaluation. The primary objective was 1-year event-free survival (EFS) after HLA allele-matched (at HLA-A, -B, -C, and -DRB1 loci) unrelated donor transplant. The conditioning regimen included alemtuzumab, fludarabine, and melphalan. Graft-versus-host disease (GVHD) prophylaxis included calcineurin inhibitor, short-course methotrexate, and methylprednisolone. Transplant indications included stroke (n = 12), transcranial Doppler velocity >200 cm/s (n = 2), ≥3 vaso-occlusive pain crises per year (n = 12), or ≥2 acute chest syndrome episodes (n = 4) in the 2 years preceding enrollment. Median follow-up was 26 months (range, 12-62 months); graft rejection was 10%. The 1- and 2-year EFS rates were 76% and 69%, respectively. The corresponding rates for overall survival were 86% and 79%. The day 100 incidence rate of grade II-IV acute GVHD was 28%, and the 1-year incidence rate of chronic GVHD was 62%; 38% classified as extensive. There were 7 GVHD-related deaths. A 34% incidence of posterior reversible encephalopathy syndrome was noted in the first 6 months. Although the 1-year EFS met the prespecified target of ≥75%, this regimen cannot be considered sufficiently safe for widespread adoption without modifications to achieve more effective GVHD prophylaxis. The BMT CTN #0601 trial was registered at www.clinicaltrials.gov as #NCT00745420.

Successful matched sibling donor marrow transplantation following reduced intensity conditioning in children with hemoglobinopathies

Fifty-two children with symptomatic sickle cell disease sickle cell disease (SCD) (N = 43) or transfusion-dependent thalassemia (N = 9) received matched sibling donor marrow (46), marrow and cord product (5), or cord blood (1) allografts following reduced intensity conditioning (RIC) with alemtuzumab, fludarabine, and melphalan between March 2003 and May 2014*. The Kaplan-Meier probabilities of overall and event-free survival at a median of 3.42 (range, 0.75-11.83) years were 94.2% and 92.3% for the group, 93% and 90.7% for SCD, and 100% and 100% for thalassemia, respectively. Treatment-related mortality (all related to graft versus host disease, GVHD) was noted in three (5.7%) recipients, all 17-18 years of age. Acute and chronic GVHD was noted in 23% and 13%, respectively, with 81% of recipients off immunosuppression by 1 year. Graft rejection was limited to the single umbilical cord blood recipient who had prompt autologous hematopoietic recovery. Fourteen (27%) had mixed chimerism at 1 year and beyond; all had discontinued immunosuppression between 4 and 12 months from transplant with no subsequent consequence on GVHD or rejection. Infectious complications included predominantly bacteremia (48% were staphylococcus) and CMV reactivation (43%) necessitating preemptive therapy. Lymphocyte recovery beyond 6 months was associated with subsidence of infectious complications. All patients who engrafted were transfusion independent; no strokes or pulmonary complications of SCD were noted, and pain symptoms subsided within 6 months posttransplant. These findings support using RIC for patients with hemoglobinopathy undergoing matched sibling marrow transplantation (*www.Clinical Trials.gov: NCT00920972, NCT01050855, NCT02435901).

Advances in unrelated and alternative donor hematopoietic cell transplantation for nonmalignant disorders

PURPOSE OF REVIEW

The role of hematopoietic cell transplantation in non-malignant disorders has increased exponentially with the recognition that multiple diseases can be controlled or cured if engrafted with donor-derived cells. This review provides an overview of advances made in alternative donor transplants for nonmalignant disorders.

RECENT FINDINGS

Stem cell sources, novel transplant methods, and sophisticated supportive care have simultaneously made giant strides toward improving the safety and efficacy of hematopoietic cell transplantation. This has led to the utilization of marrow, cord, peripheral blood stem cell and haploidentical stem cell sources, and novel reduced toxicity or reduced intensity conditioning regimens to transplant non-malignant disorders such as immune dysfunctions, marrow failure syndromes, metabolic disorders and hemoglobinopathies. Transplant complications such as graft rejection, infections, and graft versus host disease are better combated in this modern era of medicine, achieving better survival with decreased late effects. These aspects of transplant for non-malignant disorders are discussed.

SUMMARY

This review presents the progress made in the realm of hematopoietic cell transplantation for non-malignant disorders. It advocates the consideration of alternative donor transplants in the absence of human leukocyte antigen matched siblings when indicated by disease severity. The ultimate goal is to provide curative transplant options for more patients that can benefit from this intervention, prior to detrimental outcomes.