ORAL MICROBIOME INFLUENCES THE CLINICAL COURSE OF ORAL MUCOSITIS IN ALLOGENEIC HSCT PATIENTS

Abstract

<h3>Objectives</h3> Oral mucositis (OM) is a complex acute cytotoxicity of antineoplastic treatment that affects 40% to 85% of patients undergoing hematopoietic stem cell transplantation. Clinically, OM is characterized by redness or ulceration covered by a pseudomembrane of cellular debris and bacterial colonies that usually develops within 5 to 7 days after the conditioning drug's administration. Incidence of OM is associated with prolonged hospitalization, extensive analgesic pharmacotherapy, parenteral nutrition, and elevated treatment costs. In this context, the identification of patient risks for OM is fundamental to enhance supportive care in oncology. OM onset relies on mucosal microenvironment status, with a possible role of microbiota-driven inflammation. We aimed to investigate whether the oral mucosa microbiota was associated with the clinical course of OM. <h3>Study Design</h3> We collected oral mucosa samples from 30 patients undergoing allogeneic hematopoietic stem cell transplantation at preconditioning. During the period of the study, 13 of 30 patients developed OM. For those patients, additional oral mucosa samples were collected at OM ulceration onset and ulcerated OM healing. All samples were characterized by 16S rRNA sequencing. <h3>Results</h3> We observed that specific taxa were associated with OM risk, severity, and time to resolution. In particular, at preconditioning, higher relative abundance of <i>Lactococcus</i> was associated with an increased ulcerated OM risk (75% vs 33%; <i>P</i> = .034), and the relative abundance of <i>Porphyromonas</i> was positively correlated with ulcerated OM grade (rho = 0.605, <i>P</i> = .028). Additionally, we observed that higher relative abundance of <i>Solobacterium</i> at OM onset was associated with prolonged OM ulcerated duration (<i>P</i> = .0005), whereas higher relative abundance of <i>Lactobacillus</i> was associated with shortened ulcerated OM duration (<i>P</i> = .032). <h3>Conclusions</h3> This was the first study to investigate oral mucosa taxa as biomarkers for OM clinical course in patients undergoing allogeneic hematopoietic stem cell transplantation. Our findings suggest that further research should focus on evaluating the influence of host-microbiome interactions on OM pathophysiology.