Sometimes follow-on drugs are flubs that would have been better put in the trash can, but I don't think that'll be the case for Johnson & Johnson's (NYSE:JNJ) Simponi: it was approved on Friday for treating three different inflammation diseases, including rheumatoid arthritis.

The TNF-alpha inhibitor enters a crowded market that includes Abbott Laboratories' (NYSE:ABT) Humira, Amgen (NASDAQ:AMGN) and Wyeth's (NYSE:WYE) Enbrel, and Johnson & Johnson's own Remicade. But the drug has a couple of distinct advantages that should help it get the traction that so many me-too drugs fail to find.

First, Simponi is injected once a month, which is better than the other TNF-alpha inhibitors that are injected two to four times a month. It's not a huge advantage -- the first company to develop an oral drug that works well for rheumatoid arthritis should do extremely well -- but the reduced number of needle pokes should be a decent selling point.

Second and more importantly, Simponi has been shown to work well in patients that have failed other TNF-alpha drugs. Because approximately 20% of patients fail to respond to the currently available drugs, there's a fairly large market that Simponi can move into.

While the marketing in the U.S. is all set, overseas it's far from clear who will market the drug if it gets approved. In 2007, Johnson & Johnson and Schering-Plough (NYSE:SGP) revised their agreement to market Remicade and its follow-on Simponi for 15 years after approval. But the pact can be terminated if Schering-Plough undergoes a change of control.

Trying to avoid this, Merck (NYSE:MRK) set up its acquisition of Schering-Plough as a reverse merger, with Schering taking over Merck and then changing its name to Merck. Sneaky? Heck, yes. Will Johnson & Johnson stand for it? I doubt it, but the health-care giant isn't giving any hints as to exactly how this is going to work out. All J&J's CEO had to say at last week's annual meeting was, "I can't disclose any of the discussions we're having," adding, "Rest assured we're not sitting back and doing nothing."

Between battling with entrenched leaders and fighting with indirect generic competition from first-generation drugs going off patents, follow-on drugs often have a rough time of it. But Simponi seems different enough that it might be able to make a serious dent in the anti-inflammatory market ... even if the brand name sounds like a pasta dish.

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