Personalizing Cancer Treatment in the Age of Global Genomic Analyses: PALB2 Gene Mutations and the Response to DNA Damaging Agents in Pancreatic Cancer

Corresponding Author: Manuel Hidalgo, Clinical Research Program, Spanish National Cancer Research Center (CNIO), Melchor Fernandez Almagro, 3, 28029, Madrid, Spain.
Molecular Cancer Therapeutics (Impact Factor: 6.11). 01/2011; 10(1):3-8. DOI: 10.1158/1535-7163.MCT-10-0893
Source: PubMed

ABSTRACT Metastasis and drug resistance are the major causes of mortality in patients with pancreatic cancer. Once developed, the progression of pancreatic cancer metastasis is virtually unstoppable with current therapies. Here, we report the remarkable clinical outcome of a patient with advanced, gemcitabine-resistant, pancreatic cancer who was later treated with DNA damaging agents, on the basis of the observation of significant activity of this class of drugs against a personalized xenograft generated from the patient's surgically resected tumor. Mitomycin C treatment, selected on the basis of its robust preclinical activity in a personalized xenograft generated from the patient's tumor, resulted in long-lasting (36+ months) tumor response. Global genomic sequencing revealed biallelic inactivation of the gene encoding PalB2 protein in this patient's cancer; the mutation is predicted to disrupt BRCA1 and BRCA2 interactions critical to DNA double-strand break repair. This work suggests that inactivation of the PALB2 gene is a determinant of response to DNA damage in pancreatic cancer and a new target for personalizing cancer treatment. Integrating personalized xenografts with unbiased exomic sequencing led to customized therapy, tailored to the genetic environment of the patient's tumor, and identification of a new biomarker of drug response in a lethal cancer.

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Available from: Ignacio Garrido-Laguna, Aug 21, 2015
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    • "Biological significance of putative biomarkers The most effective treatment was observed in pancreatic tumor xenografts treated with MMC. It was shown previously in a patient with advanced pancreatic cancer exhibiting a biallelic inactivation of the DNA repair gene: PALB2, that MMC is a highly effective DNA damaging agent for reducing tumor size and prolonging prognosis (Villarroel et al. 2011). This is a key example of the success of personalized cancer treatment and following PALB2 gene sequencing in other patients, if they too exhibit similar genotypes, it is likely that MMC can also be successful in their treatment. "
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    ABSTRACT: In a personalized treatment designed for a patient with pancreatic cancer resistant to other treatments, the success of Mitomycin C (MMC) has been highlighted. This was revealed in a murine xenograft tumor model encompassing pancreatic adenocarcinoma cells extracted from the patient. The patient was found to exhibit a biallelic inactivation of the PALB2 gene, involved in DNA repair in addition to another mutation in the TSC2 gene that induces susceptibility of the tumor to therapeutic targets of the PI3K-mTOR pathway. The aim of the study was to apply metabolomics to elucidate the modes of action of each therapy, suggesting why MMC was so successful in this patient and why it could be a more popular choice in future pancreatic cancer treatment. The effectiveness of MMC compared to rapamycin (RM), another relevant therapeutic agent has been evaluated through liquid- and gas-chromatography mass spectrometry-based metabolomic analyses of the xenograft tumors. The relative concentrations of many metabolites in the xenograft tumors were found to be increased by MMC relative to other treatments (RM and a combination of both), including a number that are involved in central carbon metabolism (CCM). Metabolic fingerprinting revealed statistically significantly altered pathways including, but not restricted to, the pentose phosphate pathway, glycolysis, TCA cycle, purine metabolism, fatty acid biosynthesis, in addition to many significant lipid and amino acid alterations. Given the genetic background of the patient, it was expected that the combined therapy would be most effective; however, the most effective was MMC alone. It is proposed that the effectiveness of MMC is owed to its direct effect on CCM, a vital region of tumor metabolism.
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