Administering With Arsenic Trioxide Attenuates Acute Promyelocytic Leukemia in Mice by Restoring Immune Microenvironment and Intestinal Homeostasis.

[OBJECTIVE] Arsenic trioxide (ATO) is a cornerstone of acute promyelocytic leukemia (APL) therapy but induces severe gut microbiota dysbiosis, limiting its efficacy and safety. This study investigated whether adjunctive (BP) could mitigate these adverse effects and enhance therapeutic outcomes.

[METHODS] 16S rRNA gene sequencing data of gut microbiota were obtained from a cohort of 22 APL patients treated with ATO-based regimens (20 of 22 data were obtained and analysis further), accessible under BioProject ID PRJNA935705. To evaluate the within-sample microbial community richness and evenness, alpha and beta diversity indices were calculated. Using a murine APL model, we compared ATO monotherapy with ATO+BP co-treatment. Analyses included fecal metagenomic sequencing, single-cell RNA sequencing (sc-RNA-seq), flow cytometric immune profiling, and assessment of intestinal tight junction proteins (claudin-1, occludin, and ZO-1) via immunofluorescence.

[RESULTS] ATO treatment significantly reduced gut microbial diversity and depleted beneficial taxa. Sc-RNA-seq data showed that ATO could orchestrate the APL immune microenvironment mainly through functional activation of CD8+ T cells and monocytes. BP supplementation restored microbial homeostasis and synergistically enhanced ATO's antileukemic effect, reducing the leukemic burden in peripheral blood by 72% and in bone marrow by 64% compared to ATO alone. Mechanistically, BP preserved intestinal barrier integrity by upregulating tight junction protein expression and modulated anti-tumor immunity, notably increasing bone marrow CD8+ T cells by 2.21-fold.

[CONCLUSIONS] BP is an effective adjunct to ATO therapy, counteracting gut dysbiosis, intestinal damage, and the immune microenvironment while synergistically improving antileukemic efficacy. Targeting the gut-leukemia axis with BP represents a promising strategy for improving the precision and safety of APL treatment.