Background and objective: Immunotherapy is the fastest growing branch in oncology that have already revolutionized the treatment of few solid cancers. The number of immunotherapy trials for pancreatic cancer (PC) is growing but the vast number of different agents used make it difficult to comprehend a possible success trait of a certain type of immunotherapy. The aim of this review is to summarize and critically evaluate the outcome of immunotherapy trials for PC intended to aid the comprehensiveness for the treating physicians.
Methods: A PubMed search was performed to identify clinical trials in patients with PC, published in English from year 2000 to June 2021 and using combination of the terms immunotherapy, PC, and cross-checked the bibliography of the revised literature as the dublettes have been removed. Studies were divided into three groups depending on what immune components have been applied: passive products (peptides, antibodies, etc.), antigen-presenting cells, and adoptive cell transfer trials.
Key content and findings: The vast majority of trials, including those from most recent years, used passive products of the immune system-peptide vaccines and antibodies. The administration was often parallel to chemotherapy that was prevalently gemcitabine-based. Although immunological responses have been detected, the clinical efficacy was very limited. Trials with check point inhibitors did not show survival advantage. Dendritic cell (DC) vaccines have been associated with some clinical objective response and prolonged survival in few patients with delayed type hypersensitivity reactions. Trials with adoptive transfer therapy are lacking. The very few trials with lymphokine-activated killer (LAK)/cytokine-induced killer (CIK) cells tested only in Asian population have resulted in some clinical effects with prolonged survival. In none of the trials have the patients been preconditioned before receiving immunotherapy.
Conclusions: Although the clinical effectiveness in the majority of the reported trials has been limited, the immunological effects observed in almost all trials show a proof of concept-that immunotherapy can work. Careful re-evaluation of the clinical premises and focus on combination and cell therapy may be the way to achieve improved survival by immunotherapy in PC.
Keywords: Pancreatic cancer (PC); T cell; cancer vaccines; checkpoint inhibitors; immunotherapy.