Reduced alpha diversity of the oral microbiome correlates with short progression-free survival in patients with relapsed/refractory multiple myeloma treated with ixazomib-based therapy (AGMT MM 1, phase II trial).

Alterations in the human microbiome have been linked to several malignant diseases. Here, we investigated the oral microbiome of 79 patients with relapsed/refractory multiple myeloma (MM) treated with ixazomib-thalidomide-dexamethasone. Increased alpha diversity (Shannon index) at the phylum level was associated with longer progression-free survival (PFS) (10.2 vs 8.5 months,  = .04), particularly in patients with very long (>75% quartile) PFS . Additionally, alpha diversity was lower in patients with progressive disease ( < .05). These findings suggest an interrelationship between the oral microbiome and outcome in patients with MM and encourage a novel direction for diagnostic and/or therapeutic strategies.