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Cannabis Trial in HIV Patients Fell Far Short of Enrollment Goals, Revealing Key Barriers to Cannabinoid Research



By Dr. Benjamin Caplan, MD  |  Board-Certified Family Physician, CMO at CED Clinic  |  Evidence Watch

Clinical Insight | CED Clinic

A Canadian pilot trial testing oral CBD and THC capsules in people living with HIV could only enroll 10 out of 205 individuals approached, falling far short of its target. The report identifies cannabis-related stigma, burdensome visit schedules, and mandatory washout periods as the primary barriers to recruitment, offering critical design lessons for future cannabinoid research rather than any evidence about whether the medicines work.

Cannabis Trial in HIV Patients Fell Far Short of Enrollment Goals, Revealing Key Barriers to Cannabinoid Research

Only 10 of 205 approached individuals enrolled in CTNPT 028, a Canadian pilot randomized trial testing oral cannabinoid capsules in people living with HIV, with stigma surrounding cannabis, excessive visit burden, and mandatory three-week washout requirements cited as the major obstacles that rendered the study infeasible as originally designed.

CED Clinical Relevance
#62
Moderate Clinical Relevance
This study does not report efficacy data, but its identification of modifiable recruitment barriers is directly valuable for designing the controlled cannabinoid trials the field urgently needs.
Cannabis Clinical Trials
HIV
Study Feasibility
Recruitment Barriers
CBD & THC
Why This Matters

People living with HIV often use cannabis to manage symptoms, yet the controlled clinical trial evidence supporting or refuting this practice remains exceptionally thin. A central reason is that conducting rigorous cannabinoid trials in this population has proven operationally difficult. When a trial approaches over 200 potential participants and fewer than 5% agree to enroll, the field needs to understand precisely why before investing in larger efficacy studies. This feasibility report addresses that question directly, making it a rare piece of research infrastructure for an underserved area of clinical investigation.

Clinical Summary

CTNPT 028 was a prospective, open-label, two-arm randomized pilot trial conducted at a single HIV clinic in Montreal between August 2021 and April 2022. It tested 12 weeks of oral THC:CBD capsules (2.5 mg/2.5 mg) against CBD-only capsules (200 mg) in virally suppressed adults living with HIV who were on stable antiretroviral therapy. The rationale rested on preclinical and observational data suggesting that cannabinoids might modulate chronic inflammation and immune activation in HIV, conditions linked to long-term comorbidity despite viral suppression. This particular paper, however, reports only the feasibility and process outcomes of the trial, not its clinical or immunological results, which were published separately.

The central finding is stark: only 10 of 205 approached individuals were randomized, yielding a 4.9% enrollment rate against a target of 26. Reasons for refusal clustered around cannabis-related stigma or discomfort, the perceived burden of frequent study visits, and unwillingness to stop current cannabis use for the required three-week washout period. Among those who did enroll, medication compliance was 100% and 80% completed the 12-week protocol, suggesting the intervention itself was tolerable once participants were on board. Two participants were withdrawn for safety events, specifically transaminitis and worsening of pre-existing anemia. The authors conclude that the study was not feasible as designed and recommend that future trials reduce visit frequency, reconsider washout requirements, and address stigma through community engagement strategies. It is important to emphasize that this report carries no implications about cannabinoid efficacy in HIV.

Dr. Caplan’s Take

I appreciate the honesty of this report. It takes considerable integrity for investigators to publish a detailed account of a trial that did not meet its enrollment target, and these are exactly the papers the cannabinoid research community needs to read carefully. The 4.9% enrollment rate tells us more about the design of cannabinoid trials than it does about patient interest in cannabis therapies. In my experience, people living with HIV who use cannabis are often deeply engaged with their own treatment strategies. They are not refusing because they do not care; they are refusing because the trial asks them to stop something that may already be helping them, to attend an impractical number of visits, and to navigate the discomfort of having their cannabis use formally documented in a medical setting.

In my own clinical practice, I see the tension between research rigor and patient reality every day. When I counsel patients with HIV about cannabis, I am working with people who have already made decisions about their care based on lived experience. Future trials need to meet these individuals where they are, with pragmatic designs that minimize disruption, use remote monitoring where possible, and treat current cannabis use as a baseline variable rather than an exclusion criterion. That is the path to trials people will actually join.

Clinical Perspective

This study sits at the earliest point in the clinical research arc: it asks whether a trial can be executed, not whether an intervention works. For clinicians following the cannabinoid-HIV literature, this is an important distinction. The field has accumulated a modest body of observational and mechanistic data suggesting that cannabinoids may influence inflammatory biomarkers in people with HIV, but the leap from those signals to controlled efficacy trials has been stymied by operational barriers. This feasibility report documents those barriers with unusual specificity. It does not advance the therapeutic evidence base, but it identifies the structural obstacles that must be resolved before meaningful efficacy data can be generated.

From a pharmacological standpoint, the two safety withdrawals (transaminitis and worsening anemia in a sample of only 10) warrant attention even though they were analyzed in the companion safety paper. Clinicians prescribing or recommending cannabinoids to HIV patients on antiretroviral therapy should remain alert to hepatotoxic interactions, particularly with CBD, which inhibits CYP3A4 and CYP2C19 and can elevate levels of several antiretrovirals. The single most actionable recommendation from this paper is directed at researchers rather than prescribers: future cannabinoid trials in HIV populations should eliminate or substantially shorten mandatory washout periods

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