Project Summary Pancreatic cancer remains the most lethal disease with no effective therapeutics. We have recently made conceptual advances in targeting signature genomic deletions, a hallmark of human cancers. We demonstrated earlier that passenger deletions could confer cancer cell specific vulnerabilities, which we termed “Collateral Lethality”. We deployed this concept in targeting the SMAD4 deletion, which occurs frequently in pancreatic cancer, and have identified malic enzyme (ME) 3 as a target for collateral lethality in SMAD4-deleted pancreatic tumor cells harboring adjacent deletion of malic enzyme 2. We unexpectedly discovered that mitochondrial malic enzymes are required for the uptake of branched chain amino acids (BCAAs) in pancreatic cancer, which has been implicated as a diagnostic plasma marker for early detection of pancreatic cancer. Our overall goals are: to validate ME3 as a therapeutic target for pancreatic cancer in vitro and in PDX models (Aim 1) and in vivo using chimeric PDAC model (Aim 2); and to identify useful therapeutic agents that specifically target ME2 deleted cells (Aim 3). Our goals align well with the NCI directive on “Scientific Framework for Pancreatic Ductal Adenocarcinoma.”