What happened Shares of BioCryst Pharmaceuticals (NASDAQ: BCRX) were jumping 8.1% higher as of 11:13 a.m. EST after rising as much as 12.3% earlier in the day. The nice gain came after the biotech announced that it had filed for regulatory approval in Japan of berotralstat as a prophylactic treatment of hereditary angioedema (HAE). So what You might wonder why a regulatory submission in Japan would qualify as a significant catalyst for any biotech stock. In BioCryst's case, it's important to consider the context. Image source: Getty Images. BioCryst's shares have been extremely volatile recently. It stock has swung up and down as investors focused on the potential for the company's early-stage drug galidesivir in treating the coronavirus strain that has spread across the world. But while those stock gyrations were all based on pure speculation, BioCryst's filing for approval of berotralstat in Japan is more tangible. The drugmaker recently announced positive results from a clinical study in the country evaluating berotralstat in treating HAE. BioCryst already has a partner lined up to market berotralstat in Japan, if approved. Torii Pharmaceutical paid BioCryst $22 million up-front and will fork over another $20 million if the drug wins Japanese approval by a specified date and receives reimbursement approval above an agreed-upon level. Now what Submitting for approval doesn't necessarily mean that a drug will actually win approval. However, BioCryst thinks its chances for obtaining Japanese approval are pretty good. The company expects to potentially win a green light for berotralstat in Japan in the second half of this year. 10 stocks we like better than BioCryst PharmaceuticalsWhen investing geniuses David and Tom Gardner have a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* David and Tom just revealed what they believe are the ten best stocks for investors to buy right now... and BioCryst Pharmaceuticals wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks *Stock Advisor returns as of December 1, 2019 Keith Speights has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.Source