Concerns About Effient Side Effects Have Not Impacted Sales

A recent study warning about a potential risk of cancer from side effects of Effient, a relatively new blood thinner by Eli Lilly, appear to have had little or no impact on the drug’s sales so far, which rose more than 50% in the third quarter of 2010. 

Eli Lilly recently told investors that Effient sales reached $36.3 million in the third quarter of 2010, after only registering $22.9 million in the second quarter. However, in June 2010, U.S. researchers identified potential concerns about an increase in the relative risk of new or worsening tumor growth with Effient when compared to it’s main competitor, Plavix.

According to the findings of the study, published in the Archives of Internal Medicine, patients given Effient may be 60% more likely to develop certain solid-tumor cancers than those given Plavix. The data was gleaned from a clinical trial involving 13,608 patients, which was actually used to obtain FDA approval for the medication last year.

Effient (prasugrel) was approved by the FDA in July 2009 to prevent blood clots in people receiving angioplasty for clogged blood vessels. Lilly introduced Effient with high hopes for future sales potential. The medication has been shown to decrease the risk of cardiovascular problems, such as heart attacks, strokes and death, by 19% compared to Plavix, which generated $9.5 billion last year. However, some raised questions about the future of Effient amid the concerns about a potential risk of cancer. In addition, Lilly may face Effient lawsuits from users diagnosed with new or worsened solid tumors after taking the medication.

In the study, researchers speculated that Effient may promote cancer growth by inhibiting the body’s natural defenses against tumors. Effient prevents blood platelets from sticking together, which naturally traps tumor cells in blood vessels and helps them stick to vessel walls. Experts have called for further studies involving the medication, indicating that post-marketing trials Lilly has been required to conduct are likely not large enough to rule out a cancer link.

Lilly released a press release following the publication of the study, which defended the safety of Effient and dismissed the potential link to cancer.

In an editorial that accompanied the study in the Archives of Internal Medicine, Dr. Sanjay Kaul, a long-time critic of Effient, and Dr. George A. Diamond from the University of California Los Angeles, called for the FDA to require a black box cancer warning for Effient. They also called for doctors to limit prescriptions of Effient until more data is available, recommending that use be limited to a duration of weeks instead of months.