Research Signal – Source date 2022-01-31
In clinical trials of cancers treated by urologists, reported side effects were common for people receiving drugs that act on the immune system. But the rates changed substantially depending on whether researchers counted any event, only higher-severity events, or events classified as immune-related.
A systematic review and meta-analysis published on January 31, 2022 pooled results from 92 clinical-trial studies with 22,942 participants. Across the studies, 81.6% of participants had an any-grade treatment-related adverse event, compared with 29.3% who had a treatment-related event graded 3 or higher. For immune-related adverse events, the corresponding pooled rates were 34.3% and 10.2%.
These are four different views of overlapping event categories, not four groups of people that can be added together. The figures offer a broad picture of reported toxicity in the trials the review found; they do not give a personal forecast for a specific drug or patient.
Four rates describe different kinds of events
“Treatment-related” events were those reported as related to treatment. “Immune-related” events were classified specifically as related to immune effects. The review reported each category at any severity and at grade 3 or higher, its threshold for higher-severity events in the included trial reporting.
The 81.6% figure therefore answers a broad question: how often did trials report any-grade treatment-related events? The 29.3% figure counts the higher-severity portion of treatment-related events. Similarly, 34.3% is the any-grade estimate for immune-related events, while 10.2% is the grade 3 or higher estimate for that category. The any-grade and higher-grade rates are nested within their respective categories; they are not separate populations.
The review searched for clinical trials published from January 2010 through September 2021. It screened 2,638 records and included 92 studies with adverse-event data, covering 22,942 participants. A pooled estimate combines results across studies, so it summarizes the included trial evidence rather than describing the experience expected in every cancer type or regimen.
Cancer and treatment context mattered
When researchers considered several factors together, cancer type, whether therapy was combined with other treatment, clinical setting, and drug exposure were each associated with reported treatment-related or immune-related events. The clinical settings compared included perioperative treatment—care given around an operation—and treatment for advanced or metastatic cancer.
Those associations point to variation across the evidence base. The abstract does not provide subgroup rates that would show the size of each difference, or establish a ranking of which context carried the greatest risk. Nor does an association show that changing a treatment combination, setting, or exposure would cause a particular change in someone’s risk. The pooled percentages are useful as an overall reference, but applying them to an individual regimen would require more specific evidence.
Fatal events had separate denominators
The review reported 140 treatment-related deaths among 14,899 participants with relevant data, an overall rate of 0.94%. It separately reported 28 immune-related deaths among 10,723 participants, an overall rate of 0.26%. The denominators differ, so these figures refer to different sets of participants and should not be added or treated as directly comparable rates in one population.
Pneumonitis, an inflammation of the lungs, was among the leading causes in both categories. It accounted for 9.3% of treatment-related deaths and 35.7% of immune-related deaths. Pneumonia and respiratory failure accounted for 7.9% and 7.1% of treatment-related deaths; liver failure and hepatitis (liver inflammation) accounted for 10.7% and 7.1% of immune-related deaths. These percentages describe shares among the respective death categories, not the likelihood of death for all people receiving treatment.
What this could change
A person considering one of these immune-based cancer treatments could eventually have a safety discussion and monitoring plan shaped more reliably around their cancer, treatment combination, and clinical setting, rather than hearing only an average across many trials. The review supplies a broad account of reported toxicities and identifies contexts associated with event occurrence, but it does not provide individualized estimates or show that a particular monitoring approach improves outcomes.
A useful next step would be for independent studies to follow patients over time and test whether higher-severity and immune-related event rates hold up for particular cancers, treatment combinations, and settings using comparable definitions. If those estimates prove dependable, they could help make counseling more specific to the treatment being considered. Clinicians already counsel and monitor patients; the potential advance is greater precision in those conversations, supported by evidence that holds up across studies.
Key Sources
- Primary source: Adverse Events of Immune Checkpoint Inhibitors Therapy for Urologic Cancer Patients in Clinical Trials: A Collaborative Systematic Review and Meta-analysis.
DOI or Journal Page · Review or Meta-Analysis · 2022-01-31
Keep exploring