GW Pharmaceuticals’ Cannabis-derived drug shows promise in brain cancer trial

GW Pharmaceuticals has unveiled positive top-line results from an exploratory Phase 2 placebo-controlled clinical study of a combination of tetrahydrocannabinol (THC) and cannabidiol (CBD) in 21 patients with recurrent glioblastoma multiforme, or GBM.

GBM is a particularly aggressive brain tumor, with a poor prognosis.

GW has received Orphan Drug Designation from the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) for THC:CBD in the treatment of glioma.

The study showed that patients with documented recurrent GBM treated with THC:CBD had an 83 percent one year survival rate compared with 53 percent for patients in the placebo cohort (p=0.042). Median survival for the THC:CBD group was greater than 550 days compared with 369 days in the placebo group. THC:CBD was generally well tolerated with treatment emergent adverse events leading to discontinuation in two patients in each group.

The most common adverse events (three patients or more and greater than placebo) were vomiting (75%), dizziness (67%), nausea (58%), headache (33%), and constipation (33%). The results of some biomarker analyses are still awaited.

“The findings from this well-designed controlled study suggest that the addition of a combination of THC and CBD to patients on dose-intensive temozolomide produced relevant improvements in survival compared with placebo and this is a good signal of potential efficacy,” said Professor Susan Short, PhD, Professor of Clinical Oncology and Neuro-Oncology at Leeds Institute of Cancer and Pathology at St James’s University Hospital and principal investigator of the study.

“Moreover, the cannabinoid medicine was generally well tolerated. These promising results are of particular interest as the pharmacology of the THC:CBD product appears to be distinct from existing oncology medications and may offer a unique and possibly synergistic option for future glioma treatment.”

Justin Gover, GW’s Chief Executive Officer, said: “We believe that the signals of efficacy demonstrated in this study further reinforce the potential role of cannabinoids in the field of oncology and provide GW with the prospect of a new and distinct cannabinoid product candidate in the treatment of glioma.

“These data are a catalyst for the acceleration of GW’s oncology research interests and over the coming months, we expect to consult with external experts and regulatory agencies on a pivotal clinical development program for THC:CBD in GBM and to expand our research interests in other forms of cancer.”

The study, designed to evaluate a number of safety and efficacy endpoints, comprised an initial phase where the safety of THC:CBD in combination with dose-intense temozolomide (an oral alkylating agent that is a standard first-line treatment for GBM) was assessed in 2 cohorts of 3 patients each.

Following a satisfactory independent safety evaluation, the study then entered a randomized placebo-controlled phase where 12 patients were randomized to THC:CBD as add-on therapy compared with 9 patients randomized to placebo (plus standard of care).

Beginning in 2007 and prior to initiating this study, GW conducted substantial pre-clinical oncologic research on several cannabinoids in various forms of cancer including brain, lung, breast, pancreatic, melanoma, ovarian, gastric, renal, prostate and bladder. These studies have resulted in approximately 15 publications and show the multi-modal effects of cannabinoids on a number of the key pathways associated with tumor growth and progression.

Cannabinoids have been shown to promote autophagy (the process of regulated self-degradation by cells) via several distinct mechanisms, including acting on the AKT/mTOR pathway, an important intracellular signalling pathway that is overactive in many cancers.

In glioma, THC and CBD appear to act via distinct signalling pathways. The combination of THC and CBD showed good efficacy in various animal models of glioma, particularly when used in combination with temozolomide. Initial in vitro studies showed that the combined administration of THC and CBD led to a synergistic reduction in the viability of U87MG glioma cells when compared to the administration of each cannabinoid individually.

The co-administration of temozolomide with THC and CBD had further synergistic effects, causing a significant reduction in cell viability. These pre-clinical studies justified the initiation of the Phase 2 clinical study.

GW’s portfolio of intellectual property related to the use of cannabinoids in oncology includes a number of issued patents and pending applications in both the U.S. and Europe. This portfolio is designed to protect the use of various cannabinoids individually or in combination, in the treatment of a variety of oncology-specific disorders and product formulations.