Preconditioning Frailty Phenotype Influences Survival and Relapse for Older Allogeneic Transplantation Recipients.

Hematologic malignancies disproportionately affect older adults. Hematopoietic cell transplantation (HCT) is potentially curative, but poor overall survival (OS) has limited its use in older adults. Fried's frailty phenotype (FFP) is a geriatric assessment tool that combines objective and subjective performance measures: gait speed, grip strength, activity level, exhaustion, and weight loss. People meeting ≥3 criteria are classified as frail; 1 or 2 criteria, as pre-frail; and 0 criteria, as fit. To evaluate the association of pre-HCT FFP with post-HCT outcomes, we assessed FFP prior to conditioning for 280 HCT recipients age ≥60 years with acute leukemia or a myeloid neoplasm at 3 institutions. When analyzing survival by age group, patients age ≥70 years had inferior OS compared to patients age 60 to 69 years (P = .002), with corresponding OS estimates of 38.9% (95% confidence interval [CI], 27.8% to 49.9%) and 59.3% (95% CI, 51.9% to 65.9%). Nonrelapse mortality (NRM) also was significantly higher in the older patients (P = .0005); the 2-year cumulative incidences of NRM were 38.5% (95% CI, 27.5% to 49.2%) and 17.2% (95% CI, 12.3% to 22.8%), for older and younger recipients, respectively. The cumulative incidences of relapse did not differ by age group (P = .3435). Roughly one-third (35.5%) of the patients were fit, 57.5% were pre-frail, and 7.5% were frail, with corresponding 2-year OS estimates of 68.4% (95% CI, 57.9% to 76.8%), 45.5% (95% CI, 37.4% to 53.2%), and 45.8% (95% CI, 23.4% to 65.8%) (P = .013). FFP was not significantly associated with NRM, but being frail or pre-frail was associated with a higher rate of disease-related deaths (33.3% and 27.3%, respectively, compared with 17.4% for fit patients; P = .043). In univariate modeling of restricted mean survival time with a 3-year horizon (RMST_3y), the factors that were significantly associated were FFP, age, Karnofsky Performance Status (KPS), Disease Risk Index (DRI), and HCT-specific Comorbidity Index (HCT-CI). Of those factors, only FFP (P = .006), age (P = .006), KPS (P = .004), and DRI (P = .005) were significantly associated in multivariate modeling of RMST_3y. Estimates of RMST_3y were computed and 5 risk-groups were created with survival ranging from 31.4 months for those who were age 60 to 69 years, fit, had KPS 90 to 100, and low/intermediate-risk DRI compared to 10.5 months for those who had high-risk features for all the evaluated factors. In univariate and multivariate analyses for restricted mean time to relapse with a 3-year horizon (RMRT_3y), FFP (pre-frail versus fit, P = .007; frail versus fit, P = .061) and DRI (P = .001) were the only significant factors. Predicted RMRT_3y was longest (30.6 months) for those who were fit and had low/intermediate-risk DRI scores and shortest (19.1 months) for those who were frail and had high-risk or very high-risk DRI scores. Both age and FFP impact survival after HCT. Incorporation of FFP into pre-HCT evaluations may improve decision-making and counseling regarding HCT risk for older adults. Our findings support future trials designed to reverse frailty, such as pre-HCT supervised exercise programs, and correlative analyses to unravel the connection of frailty and relapse to generate future targets for intervention. Finally, exploration of novel HCT platforms to reduce relapse in pre-frail and frail patients, as well as reduce NRM in adults age >70 years, are warranted.

Efficacy of probiotic treatment as post-exposure prophylaxis for COVID-19: A double-blind, Placebo-Controlled Randomized trial.

BACKGROUND & AIMS: The COVID-19 pandemic continues to pose unprecedented challenges to worldwide health. While vaccines are effective, additional strategies to mitigate the spread/severity of COVID-19 continue to be needed. Emerging evidence suggests susceptibility to respiratory tract infections in healthy subjects can be reduced by probiotic interventions; thus, probiotics may be a low-risk, low-cost, and easily implementable modality to reduce risk of COVID-19. METHODS: In this initial study, we conducted a randomized, double-blind, placebo-controlled trial across the United States testing probiotic Lacticaseibacillus rhamnosus GG (LGG) as postexposure prophylaxis for COVID-19 in 182 participants who had household exposure to someone with confirmed COVID-19 diagnosed within ≤7 days. Participants were randomized to receive oral LGG or placebo for 28 days. The primary outcome was development of illness symptoms within 28 days of COVID-19 exposure. Stool was collected to evaluate microbiome changes. RESULTS: Intention-to-treat analysis showed LGG treatment led to a lower likelihood of developing illness symptoms versus placebo (26.4 % vs. 42.9 %, p = 0.02). Further, LGG was associated with a statistically significant reduction in COVID-19 diagnosis (log rank, p = 0.049) via time-to-event analysis. Overall incidence of COVID-19 diagnosis did not significantly differ between LGG and placebo groups (8.8 % vs. 15.4 %, p = 0.17). CONCLUSIONS: This data suggests LGG is associated with prolonged time to COVID-19 infection, reduced incidence of illness symptoms, and gut microbiome changes when used as prophylaxis ≤7 days post-COVID-19 exposure, but not overall incidence. This initial work may inform future COVID-19 prevention studies worldwide, particularly in developing nations where Lacticaseibacillus probiotics have previously been utilized to reduce other non-COVID infectious-morbidity. TRIAL REGISTRATION: ClinicalTrials.gov, NCT04399252, Date: 22/05/2020. https://clinicaltrials.gov/ct2/show/NCT04399252.

Financial Toxicity and Quality of Life in Patients Undergoing Stem-Cell Transplant Evaluation: A Single-Center Analysis.

PURPOSE: We investigated the prevalence of financial toxicity in a population undergoing hematopoietic cell transplantation (HCT) evaluation and measured its impact on post-transplant clinical and health-related quality-of-life outcomes. MATERIALS AND METHODS: This was a prospective study in patients undergoing evaluation for allogeneic HCT between January 1, 2018, and September 23, 2020, at a large academic medical center. Financial health was measured via a baseline survey and the comprehensive score for financial toxicity-functional assessment of chronic illness therapy (COST-FACIT) survey. The cohort was divided into three groups: none (grade 0), mild (grade 1), and moderate-high financial toxicity (grades 2-3). Health-related quality of life outcomes were measured at multiple time points. Multivariate logistic regression analysis evaluated factors associated with financial toxicity. Kaplan-Meier curves and log-rank tests was used to evaluate overall survival (OS) and nonrelapse survival. RESULTS: Of 245 patients evaluated for transplant, 176 (71.8%) completed both questionnaires (median age was 57 years, 63.1% were male, 72.2% were White, and 39.2% had myelodysplastic syndrome, 38.1% leukemia, and 13.6% lymphoma). At initial evaluation, 83 (47.2%) patients reported no financial toxicity, 51 (29.0%) with mild, and 42 (23.9%) with moderate-high financial toxicity. Patients with financial toxicity reported significant cost-cutting behaviors, including reduced spending on food or clothing, using their savings, or not filling a prescription because of costs (P < .0001). Quality of life was lower in patients with moderate-high financial toxicity at 6 months (P = .0007) and 1 year (P = .0075) after transplant. Older age (>62; odds ratio [OR], 0.33 [95% CI, 0.13 to 0.79]; P = .04) and income ≥$60,000 in US dollars (USD) (OR, 0.17 [95% CI, 0.08 to 0.38]; P < .0001) were associated with lower odds of financial toxicity. No association was noted between financial toxicity and selection for transplant, OS, or nonrelapse mortality. CONCLUSION: Financial toxicity was highly correlated with patient-reported changes in compensatory behavior, with notable impact on patient quality of life after transplant.

A pilot study to assess the feasibility of a remotely monitored high-intensity interval training program prior to allogeneic hematopoietic stem cell transplantation.

INTRODUCTION: Although allogeneic hematopoietic stem cell transplantation (HCT) can be a curative therapy for hematologic disorders, it is associated with treatment-related complications and losses in cardiorespiratory fitness and physical function. High-intensity interval training (HIIT) may be a practical way to rapidly improve cardiorespiratory fitness and physical function in the weeks prior to HCT. The primary aim of this study was to assess the feasibility of implementing a pre-HCT home-based HIIT intervention. The secondary aim was to evaluate pre to post changes in cardiorespiratory fitness and physical function following the intervention. METHODS: This was a single-arm pilot study with patients who were scheduled to undergo allogeneic HCT within six months. Patients were instructed to complete three 30-minute home-based HIIT sessions/week between the time of study enrollment and sign-off for HCT. Sessions consisted of a 5-minute warm-up, 10 high and low intervals performed for one minute each, and a 5-minute cool-down. Prescribed target heart rates (HR) for the high- and low-intensity intervals were 80-90% and 50-60% of HR reserve, respectively. Heart rates during HIIT were captured via an Apple Watch and were remotely monitored. Feasibility was assessed via retention, session adherence, and adherence to prescribed interval number and intensities. Paired t-tests were used to compare changes in fitness (VO2peak) and physical function [Short Physical Performance Battery (SPPB), 30-second sit to stand, and six-minute walk test (6MWT)] between baseline and sign-off. Pearson correlations were used to determine the relationship between intervention length and changes in cardiorespiratory fitness or functional measures. RESULTS: Thirteen patients (58.8±11.6 years) participated in the study, and nine (69.2%) recorded their training sessions throughout the study. Median session adherence for those nine participants was 100% (IQR: 87-107). Adherence to intervals was 92% and participants met or exceeded prescribed high-intensity HR on 68.8±34.8% of intervals. VO2peak improved from baseline to sign-off (14.6±3.1 mL/kg/min to 17.9±3.3 mL/kg/min; p<0.001). 30-second sit to stand and SPPB chair stand scores significantly improved in adherent participants. Improvements in 30-second sit to stand (13.8±1.5 to 18.3±3.3 seconds) and 6MWT (514.4±43.2 to 564.6±19.3) exceeded minimal clinically important improvements established in other chronic disease populations, representing the minimum improvement considered meaningful to patients. CONCLUSIONS: Findings demonstrate that implementing a pre-HCT home-based remotely monitored HIIT program is feasible and may provide benefits to cardiorespiratory fitness and physical function.

Financial incentives to increase stool collection rates for microbiome studies in adult bone marrow transplant patients.

INTRODUCTION: In order to study the role of the microbiome in hematopoietic stem cell transplantation (HCT), researchers collect stool samples from patients at various time points throughout HCT. However, stool collection requires active subject participation and may be limited by patient reluctance to handling stool. METHODS: We performed a prospective study on the impact of financial incentives on stool collection rates. The intervention group consisted of allogeneic HCT patients from 05/2017-05/2018 who were compensated with a $10 gas gift card for each stool sample. The intervention group was compared to a historical control group of allogeneic HCT patients from 11/2016-05/2017 who provided stool samples before the incentive was implemented. To control for possible changes in collections over time, we also compared a contemporaneous control group of autologous HCT patients from 05/2017-05/2018 with a historical control group of autologous HCT patients from 11/2016-05/2017; neither autologous HCT group was compensated. The collection rate was defined as the number of samples provided divided by the number of time points we attempted to obtain stool. RESULTS: There were 35 allogeneic HCT patients in the intervention group, 19 allogeneic HCT patients in the historical control group, 142 autologous HCT patients in the contemporaneous control group (that did not receive a financial incentive), and 75 autologous HCT patients in the historical control group. Allogeneic HCT patients in the intervention group had significantly higher average overall collection rates when compared to the historical control group allogeneic HCT patients (80% vs 37%, p<0.0001). There were no significant differences in overall average collection rates between the autologous HCT patients in the contemporaneous control and historical control groups (36% vs 32%, p = 0.2760). CONCLUSION: Our results demonstrate that a modest incentive can significantly increase collection rates. These results may help to inform the design of future studies involving stool collection.

Geriatric Assessment Reveals Actionable Impairments in Hematopoietic Stem Cell Transplantation Candidates Age 18 to 80 Years.

Allogeneic hematopoietic stem cell transplantation (HCT) is a potentially curative treatment for both malignant and nonmalignant hematologic diseases; however, reported rates of treatment-related mortality approach 30%. Outcomes are worse in patients who begin HCT with functional impairments. To detect such impairments, a geriatric assessment (GA) is recommended in adults age ≥65 years. Younger HCT candidates also may be impaired because of chemotherapy regimens pre-HCT. Therefore, we hypothesized that GA can be beneficial for adult patients of all ages and subsequently created a clinical pretransplantation optimization program to assess all HCT candidates using a modified GA. One-hundred fifty-seven patients were evaluated in 4 functional domains- physical, cognitive, nutritional, and psychological-at 2 time points prior to HCT-new patient evaluation (NPE) and sign-off (SO)-between October 2017 and January 2020. At NPE, 80.9% of the patients had at least 1 domain with a functional impairment, and physical (P = .006), cognitive (P = .04), and psychological (P = .04) impairments were associated with an increased likelihood of not proceeding to HCT. In addition, patients age 18 to 39 years were more likely than older patients to have a physical function impairment (P = .001). Between NPE and SO, 51.9% of the patients had resolution of 1 or more impairments, and nutritional impairment at SO was predictive of worse overall survival (P = .01). Our study shows that GA can identify functional impairments in patients of all ages. Early identification of impairments could facilitate referrals to supportive care and resolution of impairments prior to HCT, suggesting that GA could be recommended for HCT candidates of all ages.

Home-Based Hematopoietic Cell Transplantation in the United States.

Patients undergoing allogeneic (allo) and autologous (auto) hematopoietic cell transplantation (HCT) require extensive hospitalizations or daily clinic visits for the duration of their transplantation. Home HCT, wherein patients live at home and providers make daily trips to the patient's residence to perform assessments and deliver any necessary interventions, may enhance patient quality of life and improve outcomes. We conducted the first study of home HCT in the United States to evaluate this model in the US healthcare setting and to determine the effect on clinical outcomes and quality of life. This case-control study evaluated patients who received home HCT at Duke University in Durham, North Carolina, from November 2012 to March 2018. Each home HCT patient was matched with 2 controls from the same institution who had received standard treatment based on age, disease, and type of transplant for outcomes comparison. Clinical outcomes were abstracted from electronic health records, and quality of life was assessed via Functional Assessment of Cancer Therapy-Bone Marrow Transplant. Clinical outcomes were compared with Student's t-test or Fisher's exact test (continuous variables) or chi-square test (categorical variables). Quality of life scores were compared using the Student t-test. All analyses used a significance threshold of 0.05. Twenty-five patients received home HCT, including 8 allos and 17 autos. Clinical outcomes were not significantly different between the home HCT patients and their matched controls; home HCT patients had decreased incidence of relapse within 1 year of transplantation. Pre-HCT quality of life was well preserved for autologous home HCT patients. This Phase I study demonstrated that home HCT can be successfully implemented in the United States. There was no evidence that home HCT outcomes were inferior to standard-of-care treatment, and patients undergoing autologous home HCT were able to maintain their quality of life. A Phase II randomized trial of home versus standard HCT is currently underway to better compare outcomes and costs.

Cognitive impairment in candidates for allogeneic hematopoietic stem cell transplantation.

Hematopoietic cell transplant (HCT) is an increasingly common and curative treatment strategy to improve survival among individuals with malignant and nonmalignant diseases, with over one million HCTs having been performed worldwide. Neurocognitive dysfunction is a common and untoward consequence of HCT for many recipients, although few studies have examined the profile of neurocognitive impairments in HCT or their association with clinical features, such as frailty, or the incidence of pre-HCT neurocognitive impairments across all ages, which may influence post-HCT neurocognitive impairments. We examined the pattern and correlates of pre-transplant neurocognitive dysfunction in a prospective sample of adults undergoing HCT. Neurocognition was assessed using the Montreal Cognitive Assessment Battery. Frailty was assessed using the Short Physical Performance Battery. Linear regression analysis was used to examine the associations between neurocognitive performance and frailty. Neurocognitive screening profiles were also examined by partitioning MoCA into domain scores, including Executive Function and Memory. We also examined the associations between neurocognition, frailty, and clinical outcomes, including length of transplant hospitalization and survival. One hundred and ten adults were evaluated across a wide age range (range: 19-75; mean age = 54.7 [SD = 14.1]). Neurocognitive performance tended to fall below published normative levels (mean MoCA = 25.5 [SD = 4.1]), with 17% of participants demonstrating impaired performance compared with medical normative data (MoCA ≤ 22) and 34% exhibiting impaired performance relative to healthy samples (MoCA ≤ 25). Mild impairments (MoCA ≤ 25) were common across age ranges, including middle-aged patients (23% for age < 50; 35% for age 50-60, 41% for age ≥ 60), particularly for items assessing Executive Function. Greater levels of frailty associated with lower neurocognitive screening scores (r = -0.29, P < 0.01) and Executive Functioning (r = -0.24, P < 0.01), whereas greater age was associated with poorer Memory performance only (r = -0.33, P < 0.01). Greater levels of frailty prior to transplant associated with longer length of stay (ß = 0.10, P = 0.046), but were not associated with survival. Neurocognitive impairments are common among adults undergoing HCT and the pattern of performance varies by age. Pre-transplant frailty is associated with neurocognitive functioning and may portend worse post-transplant early clinical outcomes.

Enterococcus Intestinal Domination is Associated with Increased Mortality in the Acute Leukemia Chemotherapy Population.

BACKGROUND: Enterococcus intestinal domination (EID), a state of dysbiosis wherein enterococci comprise ≥30% abundance within the microbiota, has been associated with Enterococcus bacteremia, graft-versus-host disease, and mortality in the allogeneic hematopoietic stem cell transplant (allo HCT) population. The acute leukemia (AL) chemotherapy population includes patients receiving intensive chemotherapy but do not all go on to have an allo HCT. The impact of EID on outcomes including mortality in the AL chemotherapy population is unknown. METHODS: Microbiota composition from weekly stool samples was analyzed by 16S ribosomal RNA gene sequencing. Patients were analyzed in 2 cohorts: AL chemotherapy cohort and allo HCT cohort. Alpha-diversity and richness were calculated. Kaplan Meier Analysis was used to analyze mortality. RESULTS: 929 stool samples were collected from 139 patients. Both allo HCT and AL cohorts had a decline in α-diversity and richness over the course of treatment that tends not to return to baseline months later. EID was observed in at least one sample in 36% of allo HCT patients and 49% of AL patients. Patients with observed EID had lower alpha-diversity over time. Similar to the HCT cohort, AL patients with EID had reduced overall survival. We identified 4 other genera that were commonly found in ≥30% relative abundance within the microbiota, but none were associated with mortality. In fact, in allo HCT, Bacteroides abundance ≥30% was associated with improved survival. CONCLUSIONS: EID is associated with increased all-cause mortality in HCT and AL cohorts. UnlikeEID, relative abundance ≥30% by other genera is not associated with increased all-cause mortality.

Randomised, double-blind, placebo-controlled trial of Probiotics To Eliminate COVID-19 Transmission in Exposed Household Contacts (PROTECT-EHC): a clinical trial protocol.

INTRODUCTION: The COVID-19 pandemic has proven to be an unprecedented challenge to worldwide health, and strategies to mitigate the spread and severity of COVID-19 infection are urgently needed. Emerging evidence suggests that the composition of the gut microbiome and modification of microbial ecology via probiotics can affect susceptibility to a wide range of infections, including respiratory tract infections. In this study, we aim to evaluate the effects of the probiotic Lactobacillus rhamnosus GG (LGG) versus placebo on COVID-19 infection status and the gut microbiome in subjects with a household contact who has tested positive for COVID-19. METHODS AND ANALYSIS: In this double-blinded, randomised, placebo-controlled trial, we will randomise 1132 subjects having a household contact who has recently (≤7 days) tested positive for COVID-19 to daily oral LGG or placebo for 28 days. We hypothesise that taking LGG as a probiotic will protect against COVID-19 infection and reduce the severity of disease in those who become infected (primary endpoint: decreased symptoms), and will be associated with beneficial changes in the composition of the gut microbiome. Stool samples and nasal swabs will be collected to evaluate the microbiome by 16S rRNA sequencing and the presence of SARS-CoV-2 by PCR, respectively. We will also conduct multivariate analysis of demographic, behavioural, temporal, and other variables that may predict development of symptoms and other outcomes. ETHICS AND DISSEMINATION: This trial is conducted under a Food and Drug Administration Investigational New Drug for LGG, has received ethics approval by the institutional review board of Duke University and enrolment has begun. We plan to disseminate the results in peer-reviewed journals and at national and international conferences. TRIAL REGISTRATION NUMBER: NCT04399252.

Decreased Mortality in 1-Year Survivors of Umbilical Cord Blood Transplant vs. Matched Related or Matched Unrelated Donor Transplant in Patients with Hematologic Malignancies.

Allogeneic hematopoietic stem cell transplantation (HCT) has the potential to cure hematologic malignancies but is associated with significant morbidity and mortality. Although deaths during the first year after transplantation are often attributable to treatment toxicities and complications, death after the first year may be due to sequelae of accelerated aging caused by cellular senescence. Cytotoxic therapies and radiation used in cancer treatments and conditioning regimens for HCT can induce aging at the molecular level; HCT patients experience time-dependent effects, such as frailty and aging-associated diseases, more rapidly than people who have not been exposed to these treatments. Consistent with this, recipients of younger cells tend to have decreased markers of aging and improved survival, decreased graft-versus-host disease, and lower relapse rates. Given that umbilical cord blood (UCB) is the youngest donor source available, we studied the outcomes after the first year of UCB transplantation versus matched related donor (MRD) and matched unrelated donor (MUD) transplantation in patients with hematologic malignancies over a 20-year period. In this single-center, retrospective study, we examined the outcomes of all adult patients who underwent their first allogeneic HCT through the Duke Adult Bone Marrow Transplant program from January 1, 1996, to December 31, 2015, to allow for at least 3 years of follow-up. Patients were excluded if they died or were lost to follow-up before day 365 after HCT, received an allogeneic HCT for a disease other than a hematologic malignancy, or received cells from a haploidentical or mismatched adult donor. UCB recipients experienced a better unadjusted overall survival than MRD/MUD recipients (log rank P = .03, median overall survival: UCB not reached, MRD/MUD 7.4 years). After adjusting for selected covariates, UCB recipients who survived at least 1 year after HCT had a hazard of death that was 31% lower than that of MRD/MUD recipients (hazard ratio, 0.69; 95% confidence interval, 0.47-0.99; P = .049). This trend held true in a subset analysis of subjects with acute leukemia. UCB recipients also experienced lower rates of moderate or severe chronic graft-versus-host disease (GVHD) and nonrelapse mortality, and slower time to relapse. UCB and MRD/MUD recipients experienced similar rates of grade 2-4 acute GVHD, chronic GHVD, secondary malignancy, and subsequent allogeneic HCT. UCB is already widely used as a donor source in pediatric HCT; however, adult outcomes and adoption have historically lagged behind in comparison. Recent advancements in UCB transplantation such as the implementation of lower-intensity conditioning regimens, double unit transplants, and ex vivo expansion have improved early mortality, making UCB an increasingly attractive donor source for adults; furthermore, our findings suggest that UCB may actually be a preferred donor source for mitigating late effects of HCT.

Fecal microbiota diversity disruption and clinical outcomes after auto-HCT: a multicenter observational study.

We previously described clinically relevant reductions in fecal microbiota diversity in patients undergoing allogeneic hematopoietic cell transplantation (allo-HCT). Recipients of high-dose chemotherapy and autologous HCT (auto-HCT) incur similar antibiotic exposures and nutritional alterations. To characterize the fecal microbiota in the auto-HCT population, we analyzed 1161 fecal samples collected from 534 adult recipients of auto-HCT for lymphoma, myeloma, and amyloidosis in an observational study conducted at 2 transplantation centers in the United States. By using 16S ribosomal gene sequencing, we assessed fecal microbiota composition and diversity, as measured by the inverse Simpson index. At both centers, the diversity of early pretransplant fecal microbiota was lower in patients than in healthy controls and decreased further during the course of transplantation. Loss of diversity and domination by specific bacterial taxa occurred during auto-HCT in patterns similar to those with allo-HCT. Above-median fecal intestinal diversity in the periengraftment period was associated with decreased risk of death or progression (progression-free survival hazard ratio, 0.46; 95% confidence interval, 0.26-0.82; P = .008), adjusting for disease and disease status. This suggests that further investigation into the health of the intestinal microbiota in auto-HCT patients and posttransplant outcomes should be undertaken.

The gut microbiota is associated with immune cell dynamics in humans.

The gut microbiota influences development1-3 and homeostasis4-7 of the mammalian immune system, and is associated with human inflammatory8 and immune diseases9,10 as well as responses to immunotherapy11-14. Nevertheless, our understanding of how gut bacteria modulate the immune system remains limited, particularly in humans, where the difficulty of direct experimentation makes inference challenging. Here we study hundreds of hospitalized-and closely monitored-patients with cancer receiving haematopoietic cell transplantation as they recover from chemotherapy and stem-cell engraftment. This aggressive treatment causes large shifts in both circulatory immune cell and microbiota populations, enabling the relationships between the two to be studied simultaneously. Analysis of observed daily changes in circulating neutrophil, lymphocyte and monocyte counts and more than 10,000 longitudinal microbiota samples revealed consistent associations between gut bacteria and immune cell dynamics. High-resolution clinical metadata and Bayesian inference allowed us to compare the effects of bacterial genera in relation to those of immunomodulatory medications, revealing a considerable influence of the gut microbiota-together and over time-on systemic immune cell dynamics. Our analysis establishes and quantifies the link between the gut microbiota and the human immune system, with implications for microbiota-driven modulation of immunity.

The microbe-derived short-chain fatty acids butyrate and propionate are associated with protection from chronic GVHD.

Studies of the relationship between the gastrointestinal microbiota and outcomes in allogeneic hematopoietic stem cell transplantation (allo-HCT) have thus far largely focused on early complications, predominantly infection and acute graft-versus-host disease (GVHD). We examined the potential relationship of the microbiome with chronic GVHD (cGVHD) by analyzing stool and plasma samples collected late after allo-HCT using a case-control study design. We found lower circulating concentrations of the microbe-derived short-chain fatty acids (SCFAs) propionate and butyrate in day 100 plasma samples from patients who developed cGVHD, compared with those who remained free of this complication, in the initial case-control cohort of transplant patients and in a further cross-sectional cohort from an independent transplant center. An additional cross-sectional patient cohort from a third transplant center was analyzed; however, serum (rather than plasma) was available, and the differences in SCFAs observed in the plasma samples were not recapitulated. In sum, our findings from the primary case-control cohort and 1 of 2 cross-sectional cohorts explored suggest that the gastrointestinal microbiome may exert immunomodulatory effects in allo-HCT patients at least in part due to control of systemic concentrations of microbe-derived SCFAs.

Microbiota as Predictor of Mortality in Allogeneic Hematopoietic-Cell Transplantation.

BACKGROUND: Relationships between microbiota composition and clinical outcomes after allogeneic hematopoietic-cell transplantation have been described in single-center studies. Geographic variations in the composition of human microbial communities and differences in clinical practices across institutions raise the question of whether these associations are generalizable. METHODS: The microbiota composition of fecal samples obtained from patients who were undergoing allogeneic hematopoietic-cell transplantation at four centers was profiled by means of 16S ribosomal RNA gene sequencing. In an observational study, we examined associations between microbiota diversity and mortality using Cox proportional-hazards analysis. For stratification of the cohorts into higher- and lower-diversity groups, the median diversity value that was observed at the study center in New York was used. In the analysis of independent cohorts, the New York center was cohort 1, and three centers in Germany, Japan, and North Carolina composed cohort 2. Cohort 1 and subgroups within it were analyzed for additional outcomes, including transplantation-related death. RESULTS: We profiled 8767 fecal samples obtained from 1362 patients undergoing allogeneic hematopoietic-cell transplantation at the four centers. We observed patterns of microbiota disruption characterized by loss of diversity and domination by single taxa. Higher diversity of intestinal microbiota was associated with a lower risk of death in independent cohorts (cohort 1: 104 deaths among 354 patients in the higher-diversity group vs. 136 deaths among 350 patients in the lower-diversity group; adjusted hazard ratio, 0.71; 95% confidence interval [CI], 0.55 to 0.92; cohort 2: 18 deaths among 87 patients in the higher-diversity group vs. 35 deaths among 92 patients in the lower-diversity group; adjusted hazard ratio, 0.49; 95% CI, 0.27 to 0.90). Subgroup analyses identified an association between lower intestinal diversity and higher risks of transplantation-related death and death attributable to graft-versus-host disease. Baseline samples obtained before transplantation already showed evidence of microbiome disruption, and lower diversity before transplantation was associated with poor survival. CONCLUSIONS: Patterns of microbiota disruption during allogeneic hematopoietic-cell transplantation were similar across transplantation centers and geographic locations; patterns were characterized by loss of diversity and domination by single taxa. Higher diversity of intestinal microbiota at the time of neutrophil engraftment was associated with lower mortality. (Funded by the National Cancer Institute and others.).