Nelson Chao

BACKGROUND: Allogeneic hematopoietic cell transplant (allo-HCT) recipients are at increased risk for respiratory viral infections (RVIs), which invoke substantial morbidity and mortality. Limited effective antiviral options and drug resistance often hamper successful RVI treatment, creating additional burden for patients and the health care system. METHODS: Using an open-source health care claims database, we examined differences in clinical outcomes, health resource utilization, and total reimbursements during the 1-year period following allo-HCT in patients with and without any RVI infection (respiratory syncytial virus, influenza, parainfluenza virus, and human metapneumovirus). RVIs were diagnosed at any time ≤1 year after allo-HCT and identified by International Classification of Disease codes. Analyses were stratified by the presence or absence of acute or chronic graft-versus-host disease (GVHD). RESULTS: The study included 13 363 allo-HCT patients, 1368 (10.2%) of whom had a diagnostic code for any RVI. A higher proportion of patients with any RVI had pneumonia ≤1 year after allo-HCT compared to patients without any RVI, with or without GVHD. Patients with any RVI had higher all-cause mortality risk, longer length of post-allo-HCT hospital stay, higher readmission rate, and higher number of hospital days after allo-HCT compared to patients without the infection (all p < .05). Total unadjusted median reimbursements were higher for those with any RVI and each specific RVI assessed than those without the specific infection, with or without GVHD. CONCLUSION: Allo-HCT patients with RVIs had significantly worse clinical outcomes and increased health resource utilization and reimbursements during the year following allo-HCT, with or without GVHD.

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.

Microbial diversity is associated with improved outcomes in recipients of allogeneic hematopoietic cell transplantation (allo-HCT), but the mechanism underlying this observation is unclear. In a cohort of 174 patients who underwent allo-HCT, we demonstrate that a diverse intestinal microbiome early after allo-HCT is associated with an increased number of innate-like mucosal-associated invariant T (MAIT) cells, which are in turn associated with improved overall survival and less acute graft-versus-host disease (aGVHD). Immune profiling of conventional and unconventional immune cell subsets revealed that the prevalence of Vδ2 cells, the major circulating subpopulation of γδ T cells, closely correlated with the frequency of MAIT cells and was associated with less aGVHD. Analysis of these populations using both single-cell transcriptomics and flow cytometry suggested a shift toward activated phenotypes and a gain of cytotoxic and effector functions after transplantation. A diverse intestinal microbiome with the capacity to produce activating ligands for MAIT and Vδ2 cells appeared to be necessary for the maintenance of these populations after allo-HCT. These data suggest an immunological link between intestinal microbial diversity, microbe-derived ligands, and maintenance of unconventional T cells.