Study: Immunotherapy-Associated Adverse Events May Be Underreported in Clinical Trials

Adverse events (AEs) associated with immunotherapy may be more prevalent than initially reported in clinical trials, according to a new analysis.

Immunotherapy checkpoint inhibitors have changed the landscape of oncology treatment; however, their use can come with a risk of adverse effects and, in rare cases, cause serious medical problems.

For the study, researchers reviewed claims data from a large insurance database that listed adverse events due to immunotherapy to evaluate the frequency of AEs among a large population of patients with non-small cell lung cancer (NSCLC). To do this, they identified patients who received immune checkpoint inhibitors nivolumab, pembrolizumab, or atezolizumab between 2015 and 2017 and then examined the frequency of immune-related AEs.

Of the 2798 patients with NSCLC included in the analysis, 71.4% received nivolumab, 25% received pembrolizumab, and 3.6% received atezolizumab.

According to the findings, the most common immune-related adverse outcome was hypothyroidism, which occurred in 9.2% of patients. Anemia occurred in 5.7% of patients and acute kidney injury occurred in 2.8% of patients. Gastrointestinal and cardiac events were relatively rare, the researchers found.

Other adverse events included hepatitis, which occurred in 1.8% of patients, and neuritis, which occurred in 1.4%.

The analysis also showed that approximately 14% of trials report adverse events at the time of publication. One trial, KEYNOTE-24, which compared pembrolizumab versus chemotherapy, allowed the researchers to compare the initial results with population-based data. In this trial, 0.6% of patients were reported to have had hypophysitis, but the analysis found that 2.4% of patients experienced this condition.

“We believe that our study is the first to look at adverse events based on claims data, which gives a much broader, population-based perspective on outcomes than a single trial,” senior study author Elizabeth Jane Cathcart-Rake, MD, a professor of medicine at the Mayo Clinic, said in a statement. “While there have been studies comparing data from multiple trials, our approach includes a comprehensive look at outcomes for most insured patients.”

The analysis is ongoing to determine the absolute differences between trial-reported toxicities and those seen in the population at large.

The findings indicate that the frequencies of immune-related AEs may be higher than originally reported in trials that led to the FDA approvals for immunotherapies, according to the study. The researchers concluded that real world data may help refine provider and patient expectations for outcomes beyond what is reported in clinical trials.

The study results were presented at the 2018 Palliative and Supportive Care in Oncology Symposium in San Diego, California.

References

Side Effects From Certain Immunotherapy May Be Higher Than Initially Reported [news release]. ASCO’s website. https://www.asco.org/about-asco/press-center/news-releases/side-effects-certain-immunotherapies-may-be-higher-initially. Accessed November 14, 2018.