Cannabis May Help Cancer Patients Tolerate Immunotherapy — But Could Reduce Its Effectiveness | Research

The takeaway

Cannabinoids appear to reduce immune-related side effects of checkpoint inhibitor immunotherapy, but their immunosuppressive action through CB2 receptors may simultaneously undermine the anti-cancer immune response these drugs are designed to boost.

Oncologists prescribing immunotherapy, cancer patients using cannabis, and researchers studying cannabinoid-immune interactions.

What the researchers found

Cannabis use in cancer patients receiving immune checkpoint inhibitors (ICIs) reduces immune-related adverse events and improves tolerability, but several studies noted potential negative effects on clinical outcomes including overall survival and progression-free survival, possibly due to CB2-mediated immunosuppression.

Why it matters

Immune checkpoint inhibitors are among the most important cancer treatments developed in decades, but their side effects limit use. If cannabinoids can manage these side effects without undermining treatment efficacy, they could help more patients complete their immunotherapy courses.

The numbers in context

The review proposes that CB2 functions as an inhibitory immune checkpoint. CBD and CBG, with minimal CB2 agonism, may be safer therapeutic choices than THC during immunotherapy. MAGL inhibitors are also suggested as a complementary strategy.

How the study worked

Narrative review examining clinical studies of concurrent cannabinoid and immune checkpoint inhibitor use in cancer patients, alongside mechanistic analysis of CB2 receptor immunosuppressive signaling and its potential to function as an inhibitory immune checkpoint.

What this study cannot tell us

Narrative review — not a systematic review or meta-analysis. Clinical evidence is limited to a few observational studies. The CB2 immune checkpoint hypothesis, while biologically plausible, has not been directly tested in clinical trials.

How to read the evidence

Narrative review synthesizing limited clinical data with mechanistic rationale. Hypothesis-generating but not definitive.

When this study was published

Published 2025.

The bigger picture

This review reframes the CB2 receptor as an immune checkpoint — a provocative idea that could change how oncologists think about cannabis use during immunotherapy. The recommendation to favor CBD/CBG over THC during immunotherapy could have immediate clinical relevance.

Questions still open

Would switching from THC to CBD/CBG during immunotherapy preserve symptom relief without undermining treatment? Could CB2 antagonists be co-administered with cannabinoids to block immunosuppressive effects? Should oncologists screen for cannabis use before starting ICIs?

Common questions

Should I stop using cannabis during immunotherapy?

This review suggests cannabis may reduce immunotherapy effectiveness through CB2 activation. Discuss with your oncologist — CBD or CBG may be safer options than THC-heavy products during treatment, but clinical evidence is still limited.

Why might CBD be better than THC during immunotherapy?

THC strongly activates CB2 receptors, which suppress immune function. CBD and CBG have minimal CB2 activity, so they may provide symptom relief without undermining the immune response that immunotherapy needs to fight cancer.

Read the original research

Impact of cannabinoids on cancer outcomes in patients receiving immune checkpoint inhibitor immunotherapy.

Frontiers in immunology, 16, 1497829

View on PubMed ↗Publisher’s paper ↗

Citation

Vigano, MariaLuisa; Wang, Lixing; As'sadiq, Alia; Samarani, Suzanne; Ahmad, Ali; Costiniuk, Cecilia T. (2025). Impact of cannabinoids on cancer outcomes in patients receiving immune checkpoint inhibitor immunotherapy.. Frontiers in immunology, 16, 1497829. https://doi.org/10.3389/fimmu.2025.1497829