Combined SHP2 and ERK inhibition for the treatment of KRAS-driven Pancreatic Ductal Adenocarcinoma

Mutant KRAS is present in over 90% of pancreatic as well as 30-40% of lung and colorectal cancers and is one of the most common oncogenic drivers. Despite decades of research and the recent emergence of isoform-specific KRASG12C-inhibitors, most mutant KRAS isoforms, including the ones frequently associated with pancreatic ductal adenocarcinoma (PDAC), cannot be targeted directly. Moreover, targeting single RAS downstream effectors induces adaptive mechanisms leading to tumor recurrence or resistance. We report here on the combined inhibition of SHP2, a non-receptor tyrosine phosphatase upstream of KRAS, and ERK, a serine/threonine kinase and a key molecule downstream of KRAS in PDAC. This combination shows synergistic anticancer activity in vitro , superior disruption of the MAPK pathway, and significantly increased apoptosis induction compared to single-agent treatments. In vivo , we demonstrate good tolerability and efficacy of the combination. Concurrent inhibition of SHP2 and ERK induces significant tumor regression in multiple PDAC mouse models. Finally, we show evidence that 18F-FDG PET scans can be used to detect and predict early drug responses in animal models. Based on these compelling results, we will investigate this drug combination in a clinical trial (SHERPA, SH P2 and ER K inhibition in pa ncreatic cancer, [NCT04916236][1]), enrolling patients with KRAS -mutant PDAC. ### Competing Interest Statement The authors have declared no competing interest. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT04916236&atom=%2Fbiorxiv%2Fearly%2F2021%2F12%2F15%2F2021.12.14.472574.atom