Editor's Note: This article has been updated to report the correct percentage and dollar increase of Puma Biotechnology's share price.

Shares of Westwood pharmaceuticals firm Puma Biotechnology Inc. increased by nearly 300 percent Wednesday after the firm reported a successful test of a drug being developed to treat breast cancer.

Puma Biotechnology reported on Tuesday that a Phase III clinical trial of its drug neratinib resulted in test participants having a 33 percent better disease-free survival rate than those who were given a placebo. The test involved more than 2,800 patients in 41 countries.

The company’s development of neratinib is focused on the drug’s potential as a treatment for breast cancer patients, but Puma says the drug may also be useful to treat cancers of the lungs and other organs.

Puma Biotechnology plans to file for regulatory approval of neratinib in the first half of next year.

With the rise of the share price, Forbes reported that Puma Biotechnology Chief Executive Alan Auerbach appears to be Los Angeles’ newest billionaire with holdings worth some $1.3 billion.

Shares of Puma Biotechnology closed at $233.43 Wednesday after increasing by $174.40 a share, or 295 percent, on the Nasdaq.