Liver enzyme effects of medicinal cannabis in advanced cancer: a substudy of two randomised trials

This substudy investigated whether medicinal cannabis causes an elevation in alanine aminotransferase (ALT) or aspartate aminotransferase (AST) in patients with advanced malignancy and determined whether different cannabis formulations (cannabidiol (CBD) alone vs tetrahydrocannabinol (THC)/CBD combination) had differing effects on enzyme levels.

This analysis used data from two multicentre, randomised, placebo-controlled trials of escalating doses of CBD (MedCan1) or THC/CBD (MedCan2), including 287 patients with advanced cancer. Participants received escalating doses of CBD, THC/CBD or placebo. ALT and AST levels were measured at baseline, day 14 and day 28.

Medicinal cannabis did not cause elevation of ALT or AST in patients with advanced malignancy at the doses studied (up to 600 mg CBD/day). No clinically meaningful differences in liver enzyme levels were observed between CBD-only and CBD/THC combination products. Furthermore, no patients in the cannabis groups exceeded the predefined thresholds of 3× upper limit of normal (ULN) (or 5× ULN in those with liver metastases) for ALT or AST.

In patients with advanced malignancy enrolled in two clinical trials, medicinal cannabis products did not have a significant adverse impact on ALT or AST levels during the first 4 weeks of use at the doses studied.