INVESTIGATOR: Donald Abrams, M.D.
STUDY LOCATION: University of California, San Francisco
PROJECT TITLE: Marijuana in Combination with Opioids for Cancer Pain
PROJECT TYPE: Clinical Study
The study experienced difficulty with recruitment of participants, in part due to the 9-day hospitalization required for study participation. A variety of recruitment strategies were employed, including outreach to local oncologists, advertisements in local print media, and presentations at various related functions. None of these strategies were successful and the trial was discontinued.
The primary objective of this study is to evaluate the effectiveness of smoked marijuana when used as adjunctive therapy in combination with opioids to treat cancer pain. To do this, we will first conduct a non-randomized open-label study to investigate the anticipated analgesic effect of smoked marijuana when used in combination with an opiate analgesic, which will provide estimates of response rate, variance and time to treatment effect. We will also conduct a pharmacokinetic analysis in the open-label study to determine the effect of smoking marijuana on the disposition kinetics of opioid analgesics. Presuming evidence of a treatment effect in the open-label study, we will then conduct a randomized, double-blind, placebo-controlled clinical efficacy study. Both studies will be conducted in patients with persistent measurable cancer-related pain. Secondary aims in both studies include assessments of the analgesic effects of smoked marijuana on experimentally-induced acute nociception and central sensitization to determine if cancer pain is truly responsive to cannabinoids, and a description of the anti-nausea and anti-emetic effects of smoked marijuana in those subjects with opioid nausea and vomiting. Plasma THC levels, subjective effects of THC and changes in mood and quality of life will be measured in both studies as covariates. Sixteen subjects will be enrolled in the open-label study. We anticipate requiring 38 subjects for the randomized, controlled trial based on prior information about variability in pain estimates.
Both studies will be conducted in the General Clinical Research Center (GCRC) at San Francisco General Hospital, and will be comprised of four phases: (I) a 7-day outpatient period to ensure that enrolled subjects have ongoing pain despite treatment with opioids and adjunctive therapies; (II) a 2-day lead-in period in the GCRC during which baseline measurements are obtained and participants acclimate to the GCRC environment, immediately followed by: (III) an intervention phase that will last either 7 days (the open-label study) or 5 days (the randomized, controlled trial); and (IV) a 7-day outpatient post-study period during which subjects record evidence of continued analgesic effect or withdrawal.