Introduction High-grade serous ovarian cancer (HGSOC) is the most common and aggressive form of epithelial ovarian cancer. There is an unmet need to develop novel therapeutics for HGSOC. Cannabis sativa bioactive compounds, cannabidiol (CBD) and cannabigerol (CBG), exert anti-cancer effects. The aim of this research was to investigate these compounds for the treatment of HGSOC.

Methods HGSOC cell lines (COV318, OVCAR-4 and CAOV-3) and a non-cancerous fibroblast cell line (HFF2) were treated with CBD, CBG, cannabidiolic acid (CBDA) and Cannabis extract (0 µM – 100 µM) for 72h and 144h to establish their effects on cell viability, using the MTT assay. Synergy/antagonism between CBD and CBG (0 µM – 50 µM) in combination with carboplatin (0 µM – 150 µM) or paclitaxel (0 nM – 15 nM) was investigated using the MTT assay.

Results CBD, CBG and CBDA significantly reduced the viability of HGSOC cell lines in a dose-dependent manner. CBD was the most efficacious compound, with IC50 values between 11.82 – 25.58 µM, after 72h. Cannabis extract performed exceptionally well in reducing viability of HGSOC cell lines. An average of 0.0059% (v/v) extract solution (containing 3.96 µM CBDA, 4.17 µM CBD) resulted in 50% reduction in viability, after 144h. CBD increased the efficacy of paclitaxel in reducing viability of HGSOC cell lines. However, in combination with carboplatin, antagonism was observed.

Conclusion/Implications Cannabis sativa bioactive compounds represent a potential novel therapeutic for HGSOC. Elucidating the interactions of Cannabis compounds with chemotherapy is of huge clinical relevance and may lead to the development of combination treatments.