Non-small cell lung cancer (NSCLC) is the most common type of lung cancer. There are several studies which demonstrate a role for the immune system in fighting lung cancer. However, there are multiple mechanisms by which cancer dampens this response. The PD-1 receptor-ligand interaction is one of the major pathways hijacked by tumours to help evade detection and elimination by the cells of the immune system. A number of compounds which block this pathway, including the drug pembrolizumab, have shown impressive results in some patients.~At present all of the trials with pembrolizumab reported thus far have been in patients with a good Performance Status of 0-1, a measure of daily activity. Unfortunately many patients with lung cancer have impaired performance status, making them ineligible for trials of new therapies including anti PD-1. Clinical trials of standard-of-care therapy have been successfully performed in the PS=2 only population demonstrating the feasibility of performing clinical trials in this population.~In this trial, the investigators would like to determine whether this drug can be used to treat Performance status 2 patients with a lower general daily activity. The purpose of this trial is to determine that pembrolizumab is safe and tolerable. The investigators would also like to see how well the treatment works, find out more information about tumour shrinkage, and learn more about the disease and how it changes over time.
This study is to determine that pembrolizumab is safe and tolerable at the selected dose for the treatment of Non-Small Cell Lung Cancer (NSCLC) in patients with a performance status of 2. All patients will receive pembrolizumab.