Side effect analysis suggests Gilead's hep C wonder Sovaldi is safer than rivals, too

Gilead's Sovaldi--Courtesy of Gilead

Gilead Sciences' ($GILD) breakthrough drug Sovaldi isn't just the newest hepatitis C drug to hit the market, or the fastest selling. It's also the safest, according to an early analysis of adverse event reports.

AdverseEvents, a company that specializes in analyzing FDA side effect reports for payers and healthcare providers, put Sovaldi at the top of the heap in a recent look at a range of hep C drugs. The company obtained the Sovaldi-related reports via a Freedom of Information Act request, and after sifting them, identified 407 cases of serious side effects reported by hep C patients or their doctors.

Conclusions, after those flagged side effects were examined? Similar to those often made when looking at a treatment for patients who are already seriously ill. AdverseEvents found 19 deaths and 48 hospitalizations, but "many of those cases appear to be associated with complications from advanced [hepatitis C]," the report states.

As for the other reports, most of them matched the side effects already listed on Sovaldi's official FDA label. One--memory impairment--cropped up more often than expected, but as the report notes, memory problems also are associated with chronic hepatitis C infection.

Overall, most of the reported side effects were mild, and most of the outcomes of those side effects weren't serious, the AdverseEvents report states. So, Sovaldi earned an "Rx Score"--a measurement on a 100-point scale--of 15.36. For comparison's sake, the next-safest hep C drug, according to AdverseEvents, is Merck's ($MRK) Victrelis, with a score of about 27. On average, the hep C treatments studied carried an Rx Score of more than 45.

With Sovaldi being such a resounding early success--more than $2 billion in first-quarter sales, after its December 2013 approval--many thousands of patients are already taking the drug. That means many thousands of patients could experience--and report--side effects. It's still early days, however, with more reports sure to come as prescription volumes continue to increase. But at least so far, Sovaldi stacks up well against the competition. And with payers up in arms about its $1,000-per-pill sticker price, that's important.

As AdverseEvents notes, Gilead has stood by its pricing, contending that Sovaldi has a high cure rate, and its use will save plenty of money in the long run by reducing the need for liver transplants. "Despite the high price, we saw no evidence from a safety perspective to recommend an alternative treatment should be covered by providers at this stage," the report concludes.