Researchers Warn that Side Effects of Nexium, Prilosec and Other Heartburn Drugs May Interfere with Breast Cancer Treatments: Study

The findings of a new study warn that popular heartburn drugs like Nexium, Prilosec and Prevacid may interfere with commonly used breast cancer drugs, such as Ibrance and Kisqali, leading to potentially poorer outcomes for patients.

South Korean researchers determined that women with advanced or metastatic breast cancer had lower progression-free survival and overall survival rates when they took a drug belonging to a class of drugs known as proton pump inhibitors (PPIs) at the same time as they took palbociclib, a cancer drug sold under the Ibrance and Kisqali brand names.

Their findings were published on July 21 in JAMA Network Open.

Nexium, Prilosec Impact on Breast Cancer Treatment

PPIs are designed to reduce the amount of acid in the stomach, treating gastroesophageal reflux disease (GERD), as well as heartburn, ulcers in the stomach and small intestines, and inflammation of the esophagus. In addition to Nexium, Prilosec and Prevacid, the class also includes the brand name medications Protonix, Zegerid, AcipHex, Dexilant and Vimovo, as well as a number of generic equivalents.

While the drugs have been promoted for years as safe and effective, leading many to believe they carry few serious side effects, the manufacturers have faced thousands of Nexium lawsuits, Protonix lawsuits, Prilosec lawsuits, Prevacid lawsuits  and claims over the failure to warn about side effects of PPIs, in which plaintiffs allege they have been left with acute kidney injury, chronic kidney disease, end-stage renal failure and other unexpected health problems.

In this latest study, researchers from Korea University Sejong Campus and Sungkyunkwan University sought to determine whether the use of Nexium and similar drugs led to a higher risk of cancer progression among patients with advanced or metastatic breast cancer who were also taking Ibrance or Kisqali.

The concerns rise from how proton pump inhibitors work, the researchers noted. Drugs like Nexium and Prilosec are commonly used effectively to combat gastrointestinal problems, but their acid production-reducing effects have been suspected of reducing the bioavailability of Ibrance, Kisquali and other Palbociclib-based drugs; an effect seen in some previous studies.

Researchers conducted a cohort study using nationwide claims data on 1,310 South Korean women with breast cancer from November 1, 2016 until July 31, 2021. They looked for patients whose use of palbociclib and PPIs overlapped by at least 33%, examining the time to progression of their cancer and time until death.

According to the findings, women who took PPIs at the same time as the breast cancer drugs were 76% more likely to have a shorter progression-free survival (PFS) time than women who did not take the heartburn drugs. In addition, breast cancer patients who took PPIs and Ibrance or Kisqali at the same time were nearly three times as likely to have a shorter overall survival than women who only took the cancer drug.

“These findings suggest that concomitant use of PPIs with palbociclib may hinder the complete therapeutic benefits of palbociclib in patients with breast cancer,” the researchers warned. “In this study, the clinical PFS of patients with breast cancer receiving palbociclib and PPIs in combination was approximately 15 months shorter.”

The researchers warned physicians to be cautious when prescribing drugs like Nexium, Prilosec and Prevacid to patients who are taking Ibrance or Kisqali. They also called for doctors to inform their patients of the risks of PPIs in interacting with those drugs in case they are prescribed by another healthcare provider.