The use of medical cannabis concomitantly with immune checkpoint inhibitors in non-small cell lung cancer: A sigh of relief?

The use of medical cannabis has rapidly increased among cancer patients worldwide. Cannabis is often administered concomitantly with cancer medications, including immune checkpoint inhibitors (ICIs). As the cannabinoid receptors are abundantly expressed and modulate immune cells, it has been hypothesised that cannabis may attenuate the activity of ICIs. We aimed to assess the effect of cannabis on ICIs' efficiency in patients having non-small cell lung cancer (NSCLC). The murine model of CT26 tumour-bearing mice treated with an anti-PD-1 antibody and Δ9-tetrahydrocannabinol (THC) was used to evaluate the interaction between THC and ICIs in vivo. Correlation between use of medical cannabis and clinical outcome was evaluated in a cohort of 201 consecutive metastatic NSCLC patients treated with monotherapy pembrolizumab as a first-line treatment. Median overall survival (OS) of the mice receiving a control vehicle, THC, anti-PD-1 antibody or their combination was 21, 24, 31 and 54 days, respectively (p