P-212: THE EFFECT OF UROLITHIN PRODUCTION BY GUT MICROBIOTA IN MULTIPLE MYELOMA

Introduction: Recent studies have focused on understanding the role of the gut microbiota and its production of active metabolites in hematological malignancies, including multiple myeloma (MM). Urolithin A (UA) is a natural compound produced by gut microbiota from ellagic acid that has a positive influence on the regulation of biological functions and several physiological processes. Thus its effect has been reported as beneficial in numerous diseases, including cancer. In this work, we have characterized the human microbiota and its microbial metabolites, including UA, in different stages of MM from pre-malignant stages. We also have studied the possible therapeutic potential of this metabolite in MM.

Methods: We collected 46 stool and serum samples from patients with monoclonal gammopathy of undetermined significance (n=11), smoldering myeloma (SMM) (n=9) and newly diagnosed multiple myeloma (NDMM) (n=9), at relapse/refractory (RRMM) and at complete remission (CRMM) (n=5). Furthermore, healthy patients (n=8) whose median age and gender ratio was similar to that of the patients, were included as controls. Taxonomic characterization in stool samples was performed by 16S rRNA using Illumina® MiSeq ™. LC-MS determined UA levels in serum samples. In vitro studies were performed on JJN3-GFP and U266-GFP MM cell lines as dose-response studies, western blot, immunohistochemistry, qPCR and flow cytometry. A MM xenograft model after 4 weeks of treatment with UA was used to validate the efficacy in mice.

Results: We evaluated whether the levels of UA were changed by the monoclonal gammopathy progression and its response to treatment. When we classified patients according to whether or not they had detectable urolithins levels, we found that the majority group with undetectable levels was active MM (NDMM and RRMM) (56%), while only 15% of patients with urolithin detectable levels had active disease (p=0.043). When we analyzed the levels of the microbiota related to the production of urolithins, we found some microorganisms productors of UA we associated to achieving complete remission and a higher survival. The study of the treatment with UA showed an anti-proliferative effect in monotherapy and in combination with bortezomib in MM cell lines. UA treatment significantly improved survival in an in vivo model of MM, compared to the control group (p=0.0048).

Conclusions: The presence of gut microbiota related to the production of UA and its levels were associated improving of response and survival in patients with MM. UA had an anti –tumor effect in an in vitro and in vivo a MM model. Our results suggests that this microbiota metabolite could have an anti-myeloma effect, although more studies are needed to validate its therapeutic potential.