Immunotherapy for the treatment of biliary tract cancer: an evolving landscape

Abstract

Biliary tract cancers (BTCs), consisting of intrahepatic and extrahepatic cholangiocarcinoma and gallbladder cancer, are an aggressive, heterogeneous malignancy. They are most often diagnosed in the locally advanced or metastatic setting, at which point treatment consists of systemic therapy or best supportive care. Our understanding of the tumor microenvironment and the molecular classification has led to the identification of targetable mutations, such as isocitrate dehydrogenase 1 and fibroblast growth factor receptor 2. Despite the identification of these genomic alterations, until recently, little advancement had been made in the first-line setting for advanced BTC. While immunotherapy (IO) has revolutionized the treatment of many malignancies, the use of IO in BTC had yielded limited results prior to TOPAZ-1. In this review, we discuss the systemic therapeutic advances for BTC over the past decade, the rationale for immunotherapy in BTC, prior trials utilizing IO in BTC, and current and emerging immune-based therapeutic options. We further analyze the culmination of these advances, which resulted in the approval of durvalumab with gemcitabine and cisplatin for the first-line treatment of BTC per TOPAZ-1. We also discuss the results of KEYNOTE-966, which similarly reported improved clinical outcomes with the use of pembrolizumab in combination with gemcitabine and cisplatin.

Keywords: combination therapy; immunotherapy; immunotherapy outcome; medical oncology; tumor microenvironment.

Figure 1.

Novel approaches for the treatment of BTC. Currently, multiple novel approaches are being explored for the treatment of BTC. Novel immune bispecific antibodies (anti-CTLA-4/anti-PD-1 and anti-PD-1/anti-TIGIT), as well as FDA-approved immune checkpoint inhibitors in combination with cytotoxic chemotherapy, are being studied. The host immune system is underdoing activation by adoptive cell therapy and cancer vaccines. Molecularly targeted, epigenetic, and stromal modulation therapies that modulate the TME are also under investigation. Source: created in Biorender.com. BTC, biliary tract cancer; CAR-T, chimeric antigen receptor T-cell therapy; CSF1Ri, colony-stimulating factor 1 receptor inhibitor; CTLA-4, cytotoxic T-lymphocyte associated protein 4; DNMTi, DNA methyltransferase inhibitor; FAKi, focal adhesion kinase inhibitor; HDACi, histone deacetylase inhibitor; PARPi, poly (ADP-ribose) polymerase inhibitor; PD-1, programmed cell death protein; PD-L1, programmed death-ligand 1; TCR, T cell receptor; TIGIT, T-cell immunoreceptor with Ig and ITIM domains; TME, tumor microenvironment.