Systemic therapy of gallbladder cancer: review of first line, maintenance, neoadjuvant and second line therapy specific to gallbladder cancer
Gallbladder cancer is the most common malignant cancer of the biliary tract and is distinct from other forms of biliary tract cancer in several of its risk factors and molecular aberrations. Locally advanced, unresectable and metastatic gallbladder cancer is associated with a poor prognosis and systemic chemotherapy is the main form of treatment available to these patients. This review is focused on the available evidence supporting the use of first-line chemotherapy specifically for gallbladder cancer. Numerous non-randomised studies have been published and certain forms of monotherapy and combination therapy can both lead to response rates (RRs) of approximately 40% and may prove to affect overall survival, most notably a recent phase II study of triplet therapy with gemcitabine, cisplatin and nab-paclitaxel. There are however relatively few randomised phases II and III studies on which to base recommendations, but they do demonstrate significant survival advantages of gemcitabine-containing combination therapies over best supportive care and chemotherapeutic monotherapy. The ABC-02 trial established the combination of gemcitabine and cisplatin as standard therapy in 2010, but more recent phase III studies reported as conference papers may support alternative, gemcitabine-containing doublet chemotherapy regimens such as gemcitabine in combination with oxaliplatin or S1. This manuscript also highlights the available data from studies examining maintenance chemotherapy, biomarkers, neoadjuvant therapy and second line studies in gallbladder cancer; unfortunately, there is insufficient evidence to make recommendations in these regards. The prognosis for unresectable and metastatic gallbladder cancer remains poor, and biomarkers for stratifying patients to particular first line therapies are not defined. This might be improved by gallbladder cancer specific analysis and reporting, and making histological primary specific data available publicly for further analysis.