Rituxan/MabThera

6. Rituxan/MabThera
The companies: Roche, Biogen Idec
Worldwide sales: $7.50 billion

A decade and a half on the market hasn't stopped Rituxan's sales from continuing to grow. The first monoclonal antibody treatment for cancer kept it up in 2013, with sales climbing 6% for Roche ($RHHBY) to help the company's pharma sales swell by 7% to 36.3 billion Swiss francs. The worldwide expansion came largely on the back of higher U.S. sales, which jumped by 8% thanks to increased use across both Rituxan's oncology and rheumatoid arthritis indications.

Those indications are what have Rituxan at the top of Roche's current best-sellers list--where there's plenty of competition. The world's leading cancer drugmaker has bagged label expansions for several types of blood cancer, along with the lucrative RA nod.

Like many of its peers in the best-selling biologics club, Rituxan is all over biosimilar developers' radar, and a recent report from Moody's named the drug as one of copycats' top priorities. But creating a version is not an easy task. The Swiss pharma has already seen a couple of would-be rivals throw in the towel during Phase III trials; Celltrion stopped a late-stage trial last April, and Teva ($TEVA) walked away from its own project in October of 2012.

But that doesn't mean biosimilar competition is out of the picture. Novartis' ($NVS) Sandoz unit and Boehringer Ingelheim each have candidates in Phase III trials, and Celltrion has said it would revive its Phase III program.

Luckily for Roche, it now boasts Gazyva, a Rituxan follow-up for chronic lymphocytic leukemia (CLL) that has so far beat out its predecessor at staving off the disease; the company will be working to switch patients over before Rituxan's patent expires in 2018. But while Gazyva will provide a welcome boost, it won't come anywhere near filling the giants' shoes: Analysts expect peak sales of the drug to fall between $1.5 billion and $2.5 billion.

For more:
Special Reports: Top 20 orphan drugs by 2018 - Rituxan | An ominous trend resurfaces as new drug approvals plunge in 2013 - Gazyva
AbbVie, Amgen and Roche most vulnerable to biosim rivals, Moody's says
Roche's new Gazyva beats predecessor Rituxan at staving off CLL
Roche's Rituxan successor first up in market scramble for first-line treatment of CLL
Roche figures MabThera safe from biosimilars till 2016

-- Carly Helfand (email | Twitter)

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Rituxan/MabThera