Targeted Therapies for Pancreatic Cancer and Hurdles Ahead

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive and lethal cancers with a median survival of 6 months after diagnosis. Intrinsic resistance to chemotherapeutics and lack of effective targeted therapies are the major factors contributing to dismal prognosis. Several important genetic alterations (i.e., mutations, deletions) have been identified to be involved in the initiation and progression of pancreatic cancer, including KRAS and inactivation of tumor suppressors, such as TP53, SMAD4 and CDKN2A. Unique tumor microenvironment with excessive stroma due to desmoplastic reaction is one of the major characteristics of PDAC, promoting tumor growth and leading to treatment failures. In addition, tumor stroma represents an important biological barrier for drug delivery and successful treatment of PDAC. Small interfering RNA (siRNA) has recently emerged as a potential and targeted therapeutic approach which is now evaluated in clinical trials. However, siRNAbased therapeutics face important challenges, including rapid serum degradation, poor tumor cell uptake and cellular uptake, leading to off-target effects. Therefore, there is a great need for the development of safe and effective nanoparticles for better tumor-specific delivery of anti-cancer therapeutics. In this article, the main challenges in the treatment of pancreatic cancer and recent advancements on nano delivery systems of chemotherapeutics and gene-targeted agents, used both in preclinical and clinical trials are reviewed.