Cytotoxicity of Cannabinoids in Combination with Traditional Lymphoma Chemotherapeutic Drugs Against Non-Hodgkin’s Lymphoma

<b>Background</b>: Cannabinoids (CBs) are FDA-approved for mitigating chemotherapy-induced side effects such as pain, nausea, and loss of appetite. Beyond palliative care, CBs exhibit anti-tumor properties in various cancers, including non-Hodgkin's lymphoma (NHL). Previously, we demonstrated the cytotoxic effect of endogenous and exogenous cannabinoids on human and canine B- and T-cell-type NHL cell lines. The purpose of this study was to establish the cytotoxic effect of cannabinoids in combination with the components of CHOP and lomustine. This traditional NHL chemotherapy regimen comprises cyclophosphamide, doxorubicin, vincristine, and prednisolone. <b>Methods</b>: In this study, we studied three cannabinoids, one from each of the three major categories of cannabinoids (endocannabinoid AEA, phytocannabinoid CBD, and synthetic cannabinoid WIN-55 212 22). Each cannabinoid was selected based on potency, as determined in our previous experiments. For the combination, we used five NHL chemotherapy drugs. We analyzed the cytotoxicity of each drug alone and in combinations using canine malignant B-type NHL cell line 1771 and a colorimetric MTT (3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide) cell proliferation assay and combination index (CI) based on the Chou-Talalay method. <b>Results</b>: Our results demonstrate that the cytotoxic effects of all traditional NHL chemotherapy drugs are synergistically enhanced (interaction with CI < 1) by each of the three cannabinoids at sub-IC₅₀ concentrations. <b>Conclusions</b>: This work provides a proof of concept for using cannabinoids and traditional NHL drugs in combination to reduce the dose, and thereby potentially reducing the toxicity, of chemotherapeutic drugs and increasing the survival benefit in lymphoma clinical translation studies, offering a significant advancement in cancer treatment.