Keytruda, Similar Cancer Drugs May Increase Risk of Pulmonary Embolism: Study

Findings come after a panel of scientific advisors already called for more restrictions on Keytruda, Opdivo and similar cancer drugs last month, due to moderate benefits and high risks.

Many popular and commonly used cancer drugs, like Keytruda, Opdivo and other immune checkpoint inhibitors (ICIs), may increase the risk of pulmonary embolism and other life-threatening cardiovascular events, according to the findings of a new study.

There are several types of ICIs, including PD-1 inhibitors like Keytruda, Opdivo and Libtayo, and PD-L1 inhibitors like Tecentriq and Imfiniz. The drugs are commonly used to treat cancer, by blocking proteins that regulate the immune system. This prevents the immune system from over-responding to cancer cells and damaging healthy cells. However, there have been increasing concerns in recent years that the side effects may outweigh potential benefits provided by the treatments.

In findings presented at an annual meeting hosted by the American College of Chest Physicians from October 6 to 9, researchers reported that patients with metastatic lung cancer taking cancer drugs from the class had higher rates of developing a pulmonary embolism.

A pulmonary embolism is a blood clot that travels from another part of the body through the bloodstream to an artery in the lung. The blood clot in the lung can cause serious side effects like chest pain and shortness of breath. If not treated quickly it can lead to permanent lung damage, damage to other organs and death.

In this new study, researchers from Emory University School of Medicine in Atlanta, led by Dr. Cosmo Fowler, examined data from the global TriNetX Research Network that included more than 10,500 patients with metastatic lung cancer diagnosed from 2014 to 2023. Of those, 1,630 received PD-1 inhibitors like Keytruda and Opdivo and 434 received PD-L1 inhibitors like Tecentriq.

The data indicated that 17% of patients with metastatic lung cancer who received ICIs like Keytruda or Tecentriq had a higher risk of developing a pulmonary embolism within one year of beginning treatment, compared to 14% of patients who didn’t receive ICIs. However, patients who took PD-1 inhibitors like Keytruda had a higher rate of pulmonary embolisms (20%) compared to patients taking PD-L1 inhibitors like Tecentriq (14%).

After one year of taking ICIs, cancer patients faced a 20% increased risk of suffering deep vein thrombosis, 18% increased risk of pulmonary embolism, and 12% increased risk of myocardial infarction or heart attack.

The study also noted ICIs were linked to a 19% lower risk of cerebrovascular accidents.

ICIs have helped positively change treatment for metastatic lung cancer and other cancers over the last decade. However, due to their immunosuppressing action, they can lead to an acquired autoimmune state and toxicity that can affect the organs in the body and the cardiovascular system, researchers warn.

Experts Call for Cancer Drug Restrictions

In September, a panel of expert scientific advisors to the FDA called on federal regulators to put more restrictions on drugs like Keytruda and Opdivo, especially for patients with certain types of tumors.

The panel said the drugs decrease the risk of death only moderately compared to chemotherapy, and considering some of the potential side effects, the drugs should be restricted further.

Researchers in this latest study said that as more people are prescribed the drugs for cancer, there are more reports of side effects. However, there are currently no good explanations for the findings and more study data is needed to determine the true impact of the drugs.

Study authors also said doctors treating patients with metastatic lung cancer with ICIs should be wary of signs and symptoms of thromboembolism.

The findings of the study were presented at a medical conference and are considered preliminary until published in a peer-reviewed journal.