Dose-dependent anti-proliferative activity of a bioactive hemp-derived extract REPYR-SC1 against prostate cancer

In the US approximately 1 in 8 men are diagnosed with prostate cancer, and metastatic cases account for the majority of prostate cancer-related mortality. Prostatic cancer is the second leading cause of cancer death in men, harboring a 32% 5-year survival rate. Current treatments utilize a combination of androgen deprivation therapy, androgen signaling receptor inhibitors and chemotherapy. Despite these improvements, castration-resistance and chemotherapy resistance remain a significant obstacle to sustained remission and signify a need for novel therapeutic approaches. Immunotherapies and the discovery of new anti-neoplastic agents are current modalities of considerable interest. We explore the use of REPYR-SC1, a novel hemp extract, as an anti-cancer, immunomodulatory agent following the pre-clinical evidence demonstrating anti-neoplastic efficacy of cannabinoid derivatives and their potential immunoactivity. C4 cells were used to model prostate cancer, HPrEC prostate epithelial cells as a non-cancerous control, and CTLL-2 cytotoxic T lymphocytes were chosen as a quantifiable measure of immunomodulatory capability. REPYR-SC1 was administered at 0, 0.1, 0.5, 1, and 5 μL/mL and cultured with C4, HPrEC and CTLL-2 cells for 24 and 48 hours. Morphological assessment was performed by light microscopy, pre- and post-treatment. Subsequent to this manual cell counts were performed pre-and post-treatment, followed by trypan blue exclusion assay. Only viable cells were included in the cell count. REPYR-SC1 produced a significant dose- and time-dependent reduction in proliferation (p<0.001) in prostate cancer C4 cells and CTLL-2 cells. At a dose of 1 and 5 μL/mL at the 24- and 48-hour mark, full inhibition of proliferation was observed in C4 cells. HPrEC cells showed minimal susceptibility with 20% inhibition observed for 5 μL/mL at 48 hours. CTLL-2 cells showed significant susceptibility with complete inhibition of proliferation observed at a dose of 1 and 5 µL/mL at 48 hours. REPYR-SC1 exhibited measurable immunomodulatory effects against T-lymphocytes in vitro, and selective anti-neoplastic activity versus prostate cancer cells. In conclusion, REPYR-SC1 demonstrated evidence of potential for prostate cancer inhibition and warrants further investigation.