Dordaviprone/ONC201 Activation of the ClpP Mitochondrial Protease Inhibits the Growth of KRAS-Mutant Pancreatic Cancer and Overcomes RAS Inhibitor Resistance

ABSTRACT Pancreatic ductal adenocarcinoma (PDAC) is characterized by KRAS-driven oncogenic signaling and tumor growth. Blockade of the KRAS ERK-MAPK pathway via small molecule direct RAS inhibitors has shown clinical promise, but intrinsic and acquired resistance limit the efficacy of these inhibitors as single agents. To identify potential combination strategies, we first assessed the ability of dordaviprone/ONC201, an FDA-approved agent, to inhibit PDAC cell and organoid growth. We observed that ONC201 reduced the growth of a broad panel of KRAS-mutant PDAC cell lines, and that the expression of mitochondrial protease ClpP was required for this efficacy. Mechanistically, we observed that treatment with ONC201 led to inhibition of mitochondrial respiration, causing a compensatory increase in glycolysis. Furthermore, ONC201 caused ClpP-dependent activation of PI3K-AKT-mTOR signaling and concurrent PI3K and mTOR inhibition further enhanced ONC201 growth suppression. ONC201 demonstrated an additive effect when combined with a RAS(ON) multi-selective inhibitor RMC-7977 in PDAC cells and organoids. Finally, PDAC cell lines with acquired resistance to RMC-7977 or KEAP1 loss-driven resistance retained sensitivity to ONC201. We propose that concurrent treatment with ONC201 may delay onset of resistance to RAS inhibitor therapy. Statement of Significance ClpP activation by dordaviprone/ONC201 suppressed PDAC cell growth and overcame resistance to the RAS(ON) multi-selective inhibitor RMC-7977, providing support for investigating this combination as a potential combination treatment for KRAS-mutant pancreatic cancer. Competing Interest Statement E.F. Petricoin received royalties from TheraLink Technologies, Inc. E.F. Petricoin is a shareholder and consultant of Avant Diagnostics, TheraLink Technologies, Inc., and Perthera. E.F. Petricoin received funding support from Mirati Therapeutics, Inc., a Bristol Myers Squibb company, Genentech, Inc., and Abbvie, Inc. A.D. Cox has consulted for Eli Lilly and Mirati Therapeutics, Inc., a Bristol Myers Squibb company. K.L. Bryant has received research funding support from SpringWorks Therapeutics and consulted for Merck. C.J. Der is a consultant/advisory board member for AskY Therapeutics, Cullgen, Deciphera Pharmaceuticals, Kestrel Therapeutics, Merck, Mirati Therapeutics, Inc., a Bristol Myers Squibb company, Reactive Biosciences, Revolution Medicines, and SHY Therapeutics and has received research funding support from Deciphera Pharmaceuticals, Mirati Therapeutics, Inc., a Bristol Myers Squibb company, Reactive Biosciences, Revolution Medicines, and SpringWorks Therapeutics. The other authors declare no competing interests.