Exosomal microRNAs and key pathways associated with cognitive impairment in breast cancer patients: A longitudinal study.

Abstract

e24098 Background: As mediators of intercellular communication, exosomal microRNAs (miRNAs) serve as promising biomarkers of cancer-related cognitive impairment (CRCI) while also providing mechanistic insight into the regulation of biological pathways underlying the condition. Here, we perform exosomal miRNA profiling and identify biological pathways associated with CRCI in a longitudinal study of breast cancer patients. Methods: Adult patients with a diagnosis of breast cancer (Stage I-IV) receiving any anti-cancer therapy were eligible for this longitudinal, observational study. Patients completed the Functional Assessment of Cancer Therapy-Cognitive Function (FACT-Cog) questionnaire and blood draws every 12 weeks for up to two years. RNA extracted from plasma exosomes was analyzed using small RNA-seq on an Illumina NovaSeq platform and annotated with miRBase. Normalized counts were treated as continuous measures for analysis. Differential miRNA expression analyses between timepoints with and without CRCI (FACT-Cog PCI < 60, primary endpoint) were conducted via mixed effects models adjusted for batch effects, performed separately for metastatic and non-metastatic breast cancer patients. Results were combined using Fisher’s combined probability test to identify miRNAs associated with CRCI across both groups. miRNAs with an unadjusted p-value of < 0.05 were selected for miRNA-Target network analysis and KEGG pathway enrichment using miRNet. Significance was indicated by a false discovery rate (FDR) of < 0.05. Results: Forty-two patients were included with a median follow-up of 24 weeks (IQR:12-48). Patients had a mean age of 53.6 years (SD: 11.7) and were majority Hispanic (60%) with early-stage (I-III) (52%), ER/PR+ (74%) breast cancer. Sixteen patients (38%) reported CRCI. Nine miRNAs nominally associated with CRCI, including upregulated miR-30a-5p and miR-146a-5p, were eligible for pathway analysis (unadjusted p < 0.05). 64 total pathways were significantly enriched, which were involved in inflammation (e.g. TGF-beta and chemokine signaling), neuronal function and synaptic plasticity (e.g. neurotrophin signaling, synaptic vesicle cycle), and cancer-related signaling (e.g. ErbB, p53) (all FDR < 0.05). Conclusions: Exosomal miRNA profiling implicates pathways related to inflammation, neurotransmission, and synaptic plasticity in CRCI. These findings support the feasibility of targeting exosomal miRNA-driven pathway regulation as a novel therapeutic approach for CRCI and identify specific biological pathways which may serve as targets, as well as miRNAs (e.g. miR-30a-5p, miR-146a-5p) that warrant further investigation as potential biomarkers.