Metastatic clear cell renal cell carcinomas (ccRCC) are resistant to DNA damaging chemotherapies, limiting therapeutic options for patients whose tumours are resistant to tyrosine kinase inhibitors and/or immune checkpoint therapies. Here we show that mouse and human ccRCC are frequently characterised by high levels of endogenous DNA damage and that cultured ccRCC cells exhibit intact cellular responses to chemotherapy-induced DNA damage. We identify that pharmacological inhibition of the DNA damage sensing kinase ATR with the orally administered, potent and selective drug M4344 (also called gartisertib) induces anti-proliferative effects in ccRCC cells due to replication stress and the accumulation of DNA damage in S phase. In some cells, DNA damage persists into subsequent G2/M and G1 phases, leading to the frequent accumulation of micronuclei. Daily single agent treatment with M4344 inhibited the growth of ccRCC xenograft tumours. M4344 synergises with chemotherapeutic drugs including cisplatin and carboplatin and the PARP inhibitor olaparib in mouse and human ccRCC cells. Weekly M4344 plus cisplatin treatment showed in vivo therapeutic synergy in ccRCC xenografts and was efficacious in an autochthonous mouse ccRCC model. These studies identify ATR inhibition as a potential novel therapeutic option for ccRCC.
Philipp Seidel, Anne Rubarth, Kyra Zodel, Asin Peighambari, Felix Neumann, Yannick Federkiel, Hsin Huang, Rouven Hoefflin, Mojca Adlesic, Christian Witt, David J. Hoffmann, Patrick Metzger, Ralph K. Lindemann, Frank T. Zenke, Christoph Schell, Melanie Boerries, Dominik von Elverfeldt, Wilfried Reichardt, Marie Follo, Joachim Albers, Ian J. Frew