Immune checkpoint inhibitors cause mild to severe side effects

A small Saudi study shows that the cancer therapy commonly causes mild side effects but sometimes more severe side effects



Researchers in the Kingdom of Saudi Arabia have assessed safety and tolerability of three commonly used cancer therapeutics that belong to a new class of drugs known as immune checkpoint inhibitors (ICIs). While most of the reported side effects were mild, one-third of the patients (19 out of 53) had to discontinue the treatment. 

First introduced in Saudi Arabia in 2015, ICIs are a new and rapidly growing class of anti-cancer drugs. By blocking specific immune checkpoint proteins, they make cancer cells vulnerable to the immune system. Although ICIs improve the overall survival rates and prognosis of cancer patients, they are also known to trigger immune-related adverse effects.

Researchers from the Saudi Food and Drug Authority (SFDA), King Saud Bin Abdulaziz University for Health Sciences, King Abdulaziz Medical City (KAMC) and King Abdullah Medical City analysed the medical records of 53 adult cancer patients who received ICIs treatment in KAMC between 2016 and 2018. The patients had received one of three immunotherapy drugs: 37 had been given nivolumab, 10 had been treated with atezolizumab and 6 had received pembrolizumab. 

The patients visited the emergency room an average of three times after the start of treatment. Around 41% of the patients suffered from joint pain (arthralgia), and  79% experienced general fatigue. Other frequent side effects were related to gastrointestinal disorders, such as colitis and diarrhoea. Pneumonitis occurred in 7.5% of the patients, skin reactions in 15%, and infections in 62.2%. Some patients suffered also from thyroid, renal, and liver issues.

“After the beginning of the ICIs treatment, most patients experienced mild and manageable side effects. However, there were also a few severe and life-threatening cases of colitis and pneumonitis,” says Mohammed Al Nuhait of the National Pharmacovigilance and Drug Safety Center at SFDA, who is currently affiliated with Umm Al-Qura University. 

Overall, one-third of patients had to discontinue the treatment due to adverse events: 12 (32.4%) patients on nivolumab, 6 (60%) on atezolizumab, and 1 (16.6%) on pembrolizumab. A total of 17 patients required steroids to manage the adverse effects of immunotherapy. 

“This is the first study in the Middle East that looks at the effect of ICIs in our population. We seem to have a higher rate of discontinuation and adverse events compared to other ICIs studies. However, we need to collect more data from all of the specialised hospitals in the Kingdom to confirm our findings,” says Al Nuhait. “In the future, we are planning to analyse ICIs related adverse events reported to the Saudi National Pharmacovigilance Center.”


  1. Al Nuhait, Mohammed, et al. "Real-world safety experience with immune checkpoint inhibitors in Saudi Arabia." Science Progress 104.1 (2021): 0036850421997302. | article

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