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What happened

Puma Biotechnology (NASDAQ:PBYI) was up as much as much as 15% today after announcing that the Food and Drug Administration accepted the company's marketing application for its breast cancer drug neratinib, although it's given up some of that gain as the day has progressed.

So what?

The average biotech doesn't zoom up by double-digits after the FDA accepts a marketing application. The FDA certifying the application is a foregone conclusion; it's the approval or rejection that comes months later that really matters.

But Puma Biotechnology isn't your average drugmaker. In March, the company said it had to delay filing the marketing application for neratinib, which used to go by the code name PB272, because the FDA "requested that Puma amend the current statistical analysis plan for the ExteNET trial to incorporate the FDA's recommendations with regard to rules for censoring the data for recurrent disease events or death." Essentially, Puma was including some patients in its analysis that the FDA thought shouldn't be there.

The changes didn't affect the data all that much, but investors were clearly a little worried that Puma Biotechnology still might not have gotten everything in the application that the FDA wants. If the FDA didn't consider the application complete, the agency would have issued a "refuse to file" letter, and Puma would have had to resubmit the application after fixing whatever problem the FDA discovered, restarting the time period the agency had to make a decision.

Now what?

The worry that caused today's move seems overblown to me since Puma was clearly trying to get it right on the first try. Meeting with the FDA before submitting the data discovered the discrepancy, which delayed the filing, but it would have been a longer delay if Puma had filed the application in March and then received a "refuse to file" letter at that point.

There's no real upside, here. The FDA accepting an application says that the application is complete, but doesn't say anything about the likelihood of neratinib being approved. For that, we'll have to wait until the FDA makes its ruling. Puma Biotechnology didn't disclose a PDUFA date, but assuming it's a standard review with a 12-month timeframe, investors should hear in July of next year.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.