IMPORTANCEPatients with locally advanced pancreatic cancer have historically poor outcomes. Evaluation of a total neoadjuvant approach is warranted. OBJECTIVE To evaluate the margin-negative (R0) resection rate of neoadjuvant FOLFIRINOX (fluorouracil, leucovorin, oxaliplatin, and irinotecan) and losartan followed by chemoradiotherapy for locally advanced pancreatic cancer. DESIGN, SETTING, AND PARTICIPANTSA single-arm phase 2 clinical trial was conducted at a large academic hospital from August 22, 2013, to May 22, 2018, among 49 patients with previously untreated locally advanced unresectable pancreatic cancer as determined by multidisciplinary review. Patients had Eastern Cooperative Oncology Group performance status 0 or 1 and adequate hematologic, renal, and hepatic function. Median follow-up for the analysis was 17.1 months (range, 5.0-53.7) among 27 patients still alive at study completion. INTERVENTIONS Patients received FOLFIRINOX and losartan for 8 cycles. Patients with radiographically resectable tumor after chemotherapy received short-course chemoradiotherapy (5 GyE × 5 with protons) with capecitabine. Patients with persistent vascular involvement received long-course chemoradiotherapy (50.4 Gy with a vascular boost to 58.8 Gy) with fluorouracil or capecitabine. MAIN OUTCOMES AND MEASURES R0 resection rate. RESULTSOf the 49 patients (26 women and 23 men; median age 63 years [range, 42-78 years]), 39 completed 8 cycles of FOLFIRINOX and losartan; 10 patients had fewer than 8 cycles due to progression (5 patients), losartan intolerance (3 patients), and toxicity (2 patients). Seven patients (16%) had short-course chemoradiotherapy while 38 (84%) had long-course chemoradiotherapy. Forty-two (86%) patients underwent attempted surgery, with R0 resection achieved in 34 of 49 patients (69%; 95% CI, 55%-82%). Overall median progression-free survival was 17.5 months (95% CI: 13.9-22.7) and median overall survival was 31.4 months (95% CI, 18.1-38.5). Among patients who underwent resection, median progression-free survival was 21.3 months (95% CI, 16.6-28.2), and median overall survival was 33.0 months (95% CI, 31.4 to not reached).CONCLUSIONS AND RELEVANCE Total neoadjuvant therapy with FOLFIRINOX, losartan, and chemoradiotherapy provides downstaging of locally advanced pancreatic ductal adenocarcinoma and is associated with an R0 resection rate of 61%.

SUMMARY The mechanistic target of rapamycin complex 1 (mTORC1) supports proliferation through parallel induction of key anabolic processes, including protein, lipid, and nucleotide synthesis. We hypothesized that these processes are coupled to maintain anabolic balance in cells with mTORC1 activation, a common event in human cancers. Loss of the tuberous sclerosis complex (TSC) tumor suppressors results in activation of mTORC1 and development of the tumor syndrome TSC. We find that pharmacological inhibitors of guanylate nucleotide synthesis have selective deleterious effects on TSC-deficient cells, including in mouse tumor models. This effect stems from replication stress and DNA damage caused by mTORC1-driven ribosomal RNA synthesis, which renders nucleotide pools limiting. These findings reveal a metabolic vulnerability downstream of mTORC1 triggered by anabolic imbalance.

p62/sequestosome-1 (SQSTM1) is a multifunctional adaptor protein and autophagic substrate which accumulates in cells with hyperactive mTORC1, such as kidney cells with mutations in the tumor suppressor genes TSC1 or TSC2. Here we report that p62 is a critical mediator of TSC2-driven tumorigenesis, as Tsc2+/− and Tsc2f/f Ksp-CreERT2+ mice crossed to p62−/− mice were protected from renal tumor development. Metabolic profiling revealed that depletion of p62 in Tsc2-null cells decreased intracellular glutamine, glutamate, and glutathione (GSH). p62 positively regulated the glutamine transporter Slc1a5 and increased glutamine uptake in Tsc2-null cells. We also observed p62-dependent changes in Gcl, Gsr, Nqo1 and Srxn1 which were decreased by p62 attenuation and implicated in GSH production and utilization. p62 attenuation altered mitochondrial morphology, reduced mitochondrial membrane polarization and maximal respiration, and increased mitochondrial ROS and mitophagy marker PINK1. These mitochondrial phenotypes were rescued by addition of exogenous GSH and overexpression of Sod2, which suppressed indices of mitochondrial damage and promoted growth of Tsc2-null cells. Finally, p62 depletion sensitized Tsc2-null cells to both oxidative stress and direct inhibition of glutathione biosynthesis by buthionine sulfoximine (BSO). Our findings show how p62 helps maintain intracellular pools of glutathione needed to limit mitochondrial dysfunction in tumor cells with elevated mTORC1, highlighting p62 and redox homeostasis as nodal vulnerabilities for therapeutic targeting in these tumors.