FDA Still Evaluating Insulin Glargine and Possible Cancer Risk

Roxanne Nelson


January 13, 2011

January 13, 2011 — Some studies have suggested that use of insulin glargine (Lantus; sanofi-aventis) may be associated with an increased risk for cancer, but the evidence thus far continues inconclusive. In an updated safety announcement, the US Food and Drug Administration (FDA) said today that their review is ongoing and that they have not concluded that insulin glargine use increases the risk for cancer.

As previously reported by Medscape Medical News, the FDA issued an early safety communication in July 2009 that informed the public of a possible association between use of insulin glargine and an elevated risk of developing cancer. At that time, the FDA was in the process of reviewing 4 published observational studies, of which 3 suggested an increased risk for cancer was associated with the use of insulin glargine.

The concern about an potential association between insulin glargine and cancer was first noted when a German observational study was submitted to the journal Diabetologia. The data raised the possibility that when used at high doses, this commonly prescribed insulin analog could put patients at a higher risk of developing cancer.

Three additional observational studies were subsequently conducted, based on large databases in Sweden, Scotland, and the United Kingdom. The Swedish study showed a statistically significant link between insulin glargine and breast cancer (Diabetologia. 2009;52:1745-1754), whereas the Scottish study found a nonsignificant link with breast cancer (Diabetologia. 2009;52:1755-1765), and the British study did not find an association with any type of cancer (Diabetologia. 2009;52:1766-1777).

Data Inconclusive

The FDA has now reviewed all 4 studies and has determined that the evidence presented is inconclusive, primarily because of limitations in study design and methodology. In addition, the FDA has also reviewed data from a 5-year randomized trial that compared insulin glargine with an NPH insulin in patients with type 2 diabetes. A post hoc evaluation showed that the overall occurrence of all cancers was 5.8% in the insulin glargine group vs 9.3% in the NPH insulin group (odds ratio for all cancers, 0.60; 95% confidence interval, 0.36 - 0.99).

These results did not support an increased risk for cancer associated with the product, although the FDA notes that this study was not designed or powered to evaluate cancer outcomes. These outcomes were also not verified in medical records or reviewed by oncology experts.

The FDA is continuing to work with the manufacturer of the product and the US Department of Veterans Affairs to further evaluate the potential long-term risk for cancer. The ongoing Outcome Reduction with Initial Glargine Intervention clinical trial, being conducted by the manufacturer, has been amended to have an expert panel review all cases of cancer that occur during the study period. Study results are anticipated to be available at the end of 2011.

The manufacturer also has plans to conduct 3 epidemiological studies that will further evaluate the possible cancer risk associated with the use of insulin glargine. The results of these studies are expected to be available by the end of June 2011.

At present, however, the FDA has not concluded that insulin glargine increases the risk of cancer and will continue to update the public as further information becomes available.

For now, healthcare professionals should continue to follow the recommendations on the label when prescribing this drug, and patients should continue using it as directed unless told otherwise by their clinician.

More information is available on the FDA's MedWatch Web site.

Adverse events related to use of insulin glargine therapy should be communicated to the FDA's MedWatch reporting program by telephone at 1-800-FDA-1088, by fax at 1-800-FDA-0178, online at http://www.fda.gov/medwatch, or by mail to 5600 Fishers Lane, Rockville, Maryland 20852-9787.


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