In a more comprehensive study led by Dr. Jennifer Wargo, blood, tumor, and gut microbiome of 77 patients with advanced melanoma treated with combined immune checkpoint blockade (CICB) targeting PD-1 and CTLA-4 were profiled, and a significantly higher abundance of Bacteroides intestinalis was found in patients with toxicity characterized by colitis and upregulation of mucosal IL-1β (47). Here, CTLA4 is linked to melanoma.