Radioprotective bacteria: A common symptom of radiation treatment for cancer is gastrointestinal disruption. The damage caused can become so severe and debilitating that it interrupts treatment. Guo et al. noticed that mice surviving experimental radiation exposure had distinctive taxonomic representation in their gut microbiota. A similar correlation was also observed in a small group of human subjects. Further experiments in mice revealed that some strains of bacteria produced high levels of short-chain fatty acids, which seemed to be dampening inflammatory responses and alleviating the damage caused by reactive oxygen species released by the radiation. A metabolomics analysis also implicated a role for tryptophan metabolic pathways in radiation survivorship. Science , this issue p. eaay9097

Lactose can fuel GVHD: Allogeneic hematopoietic cell transplantation (allo-HCT) is used to treat certain hematopoietic malignancies, but patients have a risk of developing graft-versus-host disease (GVHD). Stein-Thoeringer et al. performed a large-scale analysis of more than 1300 patients treated with allo-HCT across four clinical centers (see the Perspective by Zitvogel and Kroemer). High levels of bacteria from the Enterococcus genus were associated with greater incidence of GVHD and mortality. Lactose appears to provide a substrate for Enterococcus growth, and patients with a lactose-malabsorption genotype had a greater abundance of Enterococcus. A lactose-free diet limited Enterococcus growth, reduced the severity of GVHD, and improved survival in gnotobiotic mouse models. Science , this issue p. 1143 ; see also p. 1077

Burkitt lymphoma (BL) is an aggressive, MYC-driven lymphoma comprising three distinct clinical subtypes, including sporadic BLs that occur worldwide, endemic BLs that occur predominantly in sub-Saharan Africa, and immunodeficiency-associated BLs that occur primarily in the setting of HIV. In this study, we comprehensively delineated the genomic basis of BL through whole genome sequencing of 101 tumors representing all 3 subtypes of BL to identify 72 driver genes. These data were additionally informed by CRISPR screens in BL cell lines to functionally annotate the role of oncogenic drivers. Nearly every driver gene was found to have both coding and non-coding mutations highlighting the importance of whole genome sequencing for identifying driver events. Our data implicate coding and non-coding mutations in IGLL5, BACH2, SIN3A and DNMT1. EBV infection was associated with higher mutation load, with EBV type 1 showing a higher mutational burden than type 2 EBV. While sporadic and immunodeficiency-associated BLs had similar genetic profiles, endemic BLs manifested more frequent mutations in BCL7A and BCL6, and fewer genetic alterations in DNMT1, SNTB2, CTCF. Silencing mutations in ID3 were a common feature of all three subtypes of BL. In vitro, mass spectrometry-based proteomics demonstrated that the ID3 protein binds primarily to TCF3 and TCF4. In vivo knockout of ID3 potentiated the effects of MYC, leading to rapid tumorigenesis and tumor phenotypes consistent with those observed in the human disease. Key Points We investigated all three subtypes of BL by whole genome and transcriptome sequencing. Experimental validation through CRISPR screen and mouse models provides a better functional understanding of BL genetic drivers.

Key Points: Identification of a miRNA panel as a biomarker for the diagnosis, prognosis, and prediction of acute graft-versus-host disease.

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 role of haploidentical hematopoietic cell transplantation (HCT) using posttransplant cyclophosphamide (PTCy) for acute lymphoblastic leukemia (ALL) is being defined. We performed a retrospective, multivariable analysis comparing outcomes of HCT approaches by donor for adults with ALL in remission. The primary objective was to compare overall survival (OS) among haploidentical HCTs using PTCy and HLA-matched sibling donor (MSD), 8/8 HLA-matched unrelated donor (MUD), 7 /8 HLA-MUD, or umbilical cord blood (UCB) HCT. Comparing haploidentical HCT to MSD HCT, we found that OS, leukemia-free survival (LFS), nonrelapse mortality (NRM), relapse, and acute graft-versus-host disease (aGVHD) were not different but chronic GVHD (cGVHD) was higher in MSD HCT. Compared with MUD HCT, OS, LFS, and relapse were not different, but MUD HCT had increased NRM (hazard ratio [HR], 1.42; P = .02), grade 3 to 4 aGVHD (HR, 1.59; P = .005), and cGVHD. Compared with 7/8 UD HCT, LFS and relapse were not different, but 7/8 UD HCT had worse OS (HR, 1.38; P = .01) and increased NRM (HR, 2.13; P ≤ .001), grade 3 to 4 aGVHD (HR, 1.86; P = .003), and cGVHD (HR, 1.72; P ≤ .001). Compared with UCB HCT, late OS, late LFS, relapse, and cGVHD were not different but UCB HCT had worse early OS (≤18 months; HR, 1.93; P < .001), worse early LFS (HR, 1.40; P = .007) and increased incidences of NRM (HR, 2.08; P < .001) and grade 3 to 4 aGVHD (HR, 1.97; P < .001). Haploidentical HCT using PTCy showed no difference in survival but less GVHD compared with traditional MSD and MUD HCT and is the preferred alternative donor HCT option for adults with ALL in complete remission.