WNT signaling modulates PD-L1 expression in the stem cell compartment of triple-negative breast cancer

Triple-negative breast cancers (TNBCs) are characterized by a poor prognosis and lack of targeted treatments, and thus, new therapeutic strategies are urgently needed. Inhibitors against programmed death-1 (PD-1)/PD-1 ligand (PD-L1) have shown significant efficacy in various solid cancers, but their activity against TNBCs remains limited. Here, we report that human TNBCs molecularly stratified for high levels of PD-L1 (PD-L1High) showed significantly enriched expression of immune and cancer stemness pathways compared with those with low PD-L1 expression (PD-L1Low). In addition, the PD-L1High cases were significantly associated with a high stemness score (SSHigh) signature. TNBC cell lines g…