High expectations: The landscape of clinical trials of medical marijuana in oncology

Purpose: Given the infancy and evolving complexity of medicinal marijuana, an evolving political landscape, and the growing frequency of its use in cancer care, it is important for oncologists to be actively engaged in developing and successfully implementing clinical trials focusing on medical marijuana. The purpose of this study was to analyze and evaluate trends in clinical trials focused on medical marijuana in oncology. Patients and methods: Using 3 web-based registries, Clinicaltrials.gov, European Union Clinical Trials Register (EU-CTR), and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP), we queried for search terms related to marijuana and oncology. This search identified approximately 48 oncology clinical trials involving medical marijuana. We restricted our selection to clinical trials registered between January 2002 and May 2019. Data were summarized using descriptive statistics, and qualitative data were represented as frequency and percentage. Results: A total of 474,043 trials were queried in the databases and the search strategy returned 48 trials since 2002 that met criteria for analysis in the current study: 36 from ClinicalTrials.gov, 8 from EU CTR, and 4 from ICTRP. Mean trial enrollment was 370 participants, median 53, with range of 6-10000 participants. In total, 25 % trials were phase I, 12.5 % were phase I/II, 27.1 % were phase II, 4 % were phase II/III, 18.8 % were phase III, and 12.5 % were unknown. The recruitment status were "not yet recruiting", "recruiting", "active, not recruiting", "completed", "terminated/withdrawn", and "unknown" in 6 (12.5 %), 14 (29.2 %), 0 (0 %), 20 (41.7 %), 5 (10.4 %), and 3 (6.3 %) trials, respectively. The trial start years were "2002-2005., 2006-2009, 2010-2013, 2014-2017, and 2018-Present in 4 (8.3 %), 5 (10.4 %), 10 (20.8 %), 15 (31.3 %), and 14 (29.2 %) of trials, respectively. Lastly, synthetic or branded compounds were investigated in 26 (54.2 %) of trials since 2002. Conclusion: Our results indicate that across oncology, there is growing interest in clinical research in the use of medical marijuana.