Precision Medicine and Pancreatic Cancer: A Gemcitabine Pathway Approach.

OBJECTIVES:There is a need for validated predictive markers of gemcitabine response to guide precision medicine treatment in pancreatic cancer. We previously validated human equilibrative nucleoside transporter 1 as a predictive marker of gemcitabine treatment response using Radiation Therapy Oncology Group 9704. Controversy exists about the predictive value of gemcitabine metabolism pathway biomarkers: deoxycytidine kinase (DCK), ribonucleotide reductase 1 (RRM1), RRM2, and p53R2. METHODS:Radiation Therapy Oncology Group 9704 prospectively randomized 538 patients after pancreatic resection to receive either 5-fluorouracil or gemcitabine. Tumor DCK, RRM1, RRM2, and p53R protein expressions were analyzed using a tissue microarray and immunohistochemistry and correlated with treatment outcome (overall survival and disease-free survival) by unconditional logistic regression analysis. RESULTS:There were 229 patients eligible for analysis from both the 5-fluorouracil and gemcitabine arms. Only RRM2 protein expression, and not DCK, RRM1, or p53R2 protein expression, was associated with survival in the gemcitabine treatment arm. CONCLUSIONS:Despite limited data from other nonrandomized treatment data, our data do not support the predictive value of DCK, RRM1, or p53R2. Efforts should focus on human equilibrative nucleoside transporter 1 and possibly RRM2 as valid predictive markers of the treatment response of gemcitabine in pancreatic cancer.