An Australian study has found a cannabis extract is an effective adjunct for the secondary prevention of chemotherapy-induced nausea and vomiting (CINV).
The tetrahydrocannabinol/cannabidiol (THC:CBD) product has already shown promise in a phase 2 crossover component of the research previously reported in the limbic [link here].
The combined phase 2 and 3 study results, presented at the 2023 ASCO Annual Meeting in Chicago on 5 June, comprised 147 patients with any malignancy, receiving IV chemotherapy and experiencing CINV despite guideline recommended anti-emetics.
Background anti-emetic prophylaxis included mostly steroids, 5-HT3 antagonists and NK-1 antagonists.
Patients were randomised to either oral 2.5:2.5mg THC:CBD, using a self-administered, dose-titration schedule up to a maximum of 4 capsules three times per day from the day before chemotherapy to five days after chemotherapy, or placebo.
The study found the primary end point of complete response – no vomiting and no use of rescue medications over five days – was 24% with THC:CBD compared to 8% with placebo (p=0.01).
In secondary endpoints, the proportion of people not requiring rescue medications was statistically higher with THC:CBD than placebo (28% v 10%; p=0.01) and no significant nausea was reported more often in the THC:CBD arm than the placebo arm (20% v 7%; p=0.01).
The nausea score, maximum nausea score, number of vomits per day and maximum number of vomits per day were all statistically higher in the placebo group, however the proportion of patients having no vomiting was similar in both groups (70% v 58%; p=0.14)
The investigators, including medical oncologist Associate Professor Peter Grimison from the Chris O’Brien Lifehouse and the University of Sydney, concluded that THC:CBD reduced CINV despite the use of concurrent standard of care anti-emetic prophylaxis.
Associate Professor Grimison told the limbic that CBD alone is unlikely to be effective for nausea but in combination, it counteracts some of the adverse effects of THC as well as help reduce anxiety.
The study reported higher levels of moderate sedation (18% v 7%) and dizziness (10% v 0%) in the THC:CBD group than placebo group. However no serious adverse events were attributed to THC:CBD.
About 40% of the cohort reported previous cannabis use however THC:CBD, using self-titration dosing, was relatively well tolerated across the whole cohort including the 60% who had never used cannabis.
Associate Professor Grimison said the slow accrual rate for the trial might affect the generalisability of the study.
“Not all patients will want to use THC:CBD for chemotherapy-induced nausea and vomiting, due to cost, stigma, driving restrictions, or the inability to find an authorised cannabis prescriber,” he said.
Future analyses of the data will report on quality of life and cost-effectiveness outcomes.
The investigators said further research was warranted to compare THC:CBD with other anti-emetics including other cannabinoids and olanzapine.