Abstract
The Hippo pathway signaling mediated through YAP/TAZ, and the transcription factor TEAD is known to be involved in primary tumor progression. Here we report that novel TEAD inhibitors (iTEAD) cause a significant reduction in the outgrowth of lung metastases from triple negative breast cancer (TNBC) models mediated predominantly through changes in stromal immune signaling. TEAD inhibition did not affect the proliferation of TNBC cancer cells in vitro or the growth of the primary tumor in vivo . In normal mice that were treated with iTEAD in the absence of tumors, the lungs showed a decrease in pro-tumor inflammatory pathways. However, the IL12 signaling pathway was enhanced and its production from isolated lung tissue resident macrophages, but not bone marrow derived macrophages, was elevated. In syngeneic TNBC mouse models, inhibition of TEAD suppressed pro-tumor inflammation and the M2-like macrophage phenotype in lung tissues, and increased the infiltration of CD8+ T cells into the lung as well as Th1 CD4+ T cells, restoring an immune responsive microenvironment. iTEAD-treated T cells showed enhanced cytotoxicity and degranulation when co-cultured with cancer cells via increased IL-2 activity. Furthermore, TEAD inhibition or knockdown, enhanced T-cell macrophage crosstalk and anti-tumor activity in 3D tumorspheres which was reversed by IL12 neutralizing antibodies. Our data supports a multifaceted model of TEAD inhibition on the innate and adaptive immune cells as they respond to tumor cell signals and reveals an important stromal phenotype by which TEAD inhibitors could reverse immune suppression and eliminate seeded metastases in the lungs.