Possible ARB–Cancer Relationship Under Investigation by FDA

Cheryl A. Thompson

BETHESDA, MD 15 July 2010— FDA announced today that it is investigating whether a meta-analysis's finding of a small increased risk of cancer in users of angiotensin receptor blockers (ARBs) means that this type of drug causes cancer.

The agency also said it continues to believe that the benefits of ARB therapy in patients with hypertension and certain heart-related conditions outweigh the potential risks.

The meta-analysis in question examined several randomized controlled trials in which an ARB was assigned to at least one group of patients, follow-up lasted for at least one year, and at least 100 patients were enrolled.

In a Lancet Oncologyarticle released online in mid-June, the researchers reported a risk ratio of 1.08—"a modestly increased risk"—for the occurrence of a new cancer among the patients who received an ARB instead of another treatment.

The risk ratio was 1.11 when the researchers confined their analysis to trials whose protocol specified cancer as an endpoint.

Cleveland Clinic's Steven E. Nissen, well-known for his own research using meta-analysis, in an accompanying commentary called the results "disturbing and provocative." Further, he wrote, the results raise "crucial drug safety questions for practitioners and the regulatory community."

FDA said the ARB trials collected data on adverse events related to cancer.

But some of the trials, the agency said, did not have that data judged as to whether the adverse events were related to new diagnoses of cancer or preexisting cancer. Thus the number of new diagnoses of cancer during those trials is actually unknown.

FDA also pointed out that most of the patients who participated in the trials selected for the meta-analysis received telmisartan.

Seven ARBs, including telmisartan, are marketed in the United States.

FDA questioned whether the meta-analysis's findings apply to all ARBs, as is suggested by the article's title, or to only telmisartan.