Second-line treatment in inoperable pancreatic adenocarcinoma: A systematic review and synthesis of all clinical trials

There remains uncertainty regarding the optimal second-line chemotherapy in advanced pancreatic ductal adenocarcinoma (PDAC). The current recommendation of 5-fluorouracil and oxaliplatin may not be relevant in current practice, as FOLFIRINOX (5-fluorouracil, leucovorin, irinotecan and oxaliplatin) has become a more popular first line therapy in fit patients. The majority of studies in this setting are single-arm Phase II trials with significant heterogeneity of patient populations, treatments and outcomes. In this review, we sought to systematically review and synthesise all prospective data available for the second-line treatment of advanced PDAC.

Novel agents for the treatment of adenocarcinoma of the pancreas

Pancreatic cancer is a particularly challenging malignancy, given its usually advanced stage at diagnosis and its rather limited treatment options. Gemcitabine has been standard therapy for advanced pancreatic cancer for well over a decade. The addition of capecitabine or erlotinib to gemcitabine has resulted in modestly improved, although still poor, overall survival. The majority of the recently completed randomized trials, however, have failed to demonstate an improvement of newer treatments over single-agent gemcitabine. Efforts currently underway center on new cytotoxic chemotherapy drugs, as well as novel targeted agents inhibiting various molecular pathways. Newly discovered proteins and cellular elements involved in tumor growth and invasion are potential therapeutic targets, and have become the focus of current trials, as well as future clinical trials. A better understanding of the biology of the disease at the basic science level, and epidemiology and risk factors from a public-health perspective, are needed. Continued research is clearly warranted with the goal of improving survival and optimizing treatment outcomes in locally advanced and metastatic pancreatic cancer.

Pancreatic cancer: molecular pathogenesis and new therapeutic targets

Patients with pancreatic cancer normally present with advanced disease that is lethal and notoriously difficult to treat. Survival has not improved dramatically despite routine use of chemotherapy and radiotherapy; this situation signifies an urgent need for novel therapeutic approaches. Over the past decade, a large number of studies have been published that aimed to target the molecular abnormalities implicated in pancreatic tumor growth, invasion, metastasis, angiogenesis and resistance to apoptosis. This research is of particular importance, as data suggest that a large number of genetic alterations affect only a few major signaling pathways and processes involved in pancreatic tumorigenesis. Although laboratory results of targeted therapies have been impressive, until now only erlotinib, an epidermal growth factor receptor tyrosine kinase inhibitor, has demonstrated modest survival benefit in combination with gemcitabine in a phase III clinical trial. Whilst the failures of targeted therapies in the clinical setting are discouraging, lessons have been learnt and new therapeutic targets that hold promise for the future management of the disease are continuously emerging. This Review describes some of the important developments and targeted agents for pancreatic cancer that have been tested in clinical trials.

New treatment options for advanced pancreatic cancer

Pancreatic cancer has a very high mortality rate and affects approximately 230,000 individuals worldwide. Gemcitabine has become established as the standard therapy for advanced pancreatic cancer; however, the survival advantage is small. Adjuvant chemotherapy using either 5-fluorouracil or gemcitabine is now established in pancreatic cancer as an alternative therapy. Combinations of gemcitabine with either platin agents or capecitabine may be advantageous. Anti-EGFR and anti-VEGF agents have been unsuccessful but multiple tyrosine kinase inhibitors are under investigation. Of the increasing number of immunological agents, the GV1001 antitelomerase vaccine holds some interest. Targeted agents against important mitogenic pathways, including MEK/ERK, Src, PI3K/Akt, mTOR, Hedgehog and NF-kappaB, as well as agents targeting histone deacetylase, poly(ADP-ribose) polymerase, heat shock protein 90 and other agents such as beta-lapachone, hold considerable interest for further development. However, the probability of individual success is low.

Biological approaches to therapy of pancreatic cancer

Pancreatic cancer is a lethal disease and notoriously difficult to treat. Only a small proportion is curative by surgical resection, whilst standard chemotherapy for patients with advanced disease has only modest effect with substantial toxicity. Clearly there is a need for the continual development of novel therapeutic agents to improve the current situation. Improvement of our understanding of the disease has generated a large number of studies on biological approaches targeting the molecular abnormalities of pancreatic cancer, including gene therapy and signal transduction inhibition, antiangiogenic and matrix metalloproteinase inhibition, oncolytic viral therapy and immunotherapy. This article provides a review of these approaches, both investigated in the laboratories and in subsequent clinical trials.