CASPER: A Phase I trial combining calaspargase pegol-mnkl and cobimetinib in pancreatic cancer.

Asparagine synthetase (ASNS) catalyzes the biosynthesis of asparagine from aspartate and glutamine. Cells lacking ASNS, however, are auxotrophic for asparagine. Use of L-asparaginase to promote asparagine starvation in solid tumors with low ASNS levels, such as pancreatic ductal adenocarcinoma (PDAC), is a rationale treatment strategy. However, tumor cell resistance to L-asparaginase has limited its clinical utility. Our preclinical studies show that RAS/MAPK signaling circumvents L-asparaginase-induced tumor killing, but L-asparaginase and MEK inhibition potentiated tumor killing; suggesting that this combination may provide meaningful clinical benefit to patients with PDAC. This Phase I trial (NCT05034627) will evaluate the safety and tolerability of the MEK inhibitor, cobimetinib, in combination with pegylated L-asparaginase, L calaspargase pegol-mknl, in patients with locally-advanced or metastatic PDAC.