Puma Biotechnology Inc.’s progress in developing a drug for treatment of breast and lung cancers has sent its stock on a long, steady climb.

The Westwood company has cleared a number of milestones in testing since it went public in April and last month reached an agreement with regulators on the design of a trial on breast cancer patients for its sole product.

The stock has soared 90 percent since the initial public offering. It rose 9.2 percent to $26.49 for the week ended Feb. 27, making it one of the biggest gainers on the LABJ stock index. (See page 22.)

The oral drug, which the company licensed from Pfizer Inc. in 2011, offers the potential for more effective treatment and fewer side effects. Puma’s focus is treating patients with cancers that have spread to other organs.

“A more potent drug that is less toxic is very attractive,” said Frank Gentile, vice president at Boston investment firm Tekla Capital Management LLC, which invested in Puma before its IPO. “A drug given orally is also attractive because it can be given more easily to the patients. You could probably give more of the drug to the patient and have better efficacy.”

Puma recently reached an agreement with the Food and Drug Administration on a late phase of testing for its drug, neratinib, in advanced-stage breast cancer patients.

Chief Executive Alan Auerbach said the company is moving quickly to make the drug available and will have data on many potential uses by summer. It could reach the market as early as 2014. Being a single-product company allows his 50-employee team to focus on developing the drug as quickly as possible, he added.

“We are moving very aggressively because we’re fighting a very aggressive disease,” Auerbach told the Business Journal.

Before Puma, Auerbach was chief executive of Cougar Biotechnology, which he sold to Johnson & Johnson in 2009 for about $1 billion when its prostate cancer drug was deep into late trials. Eric Schmidt, an analyst at Cowen and Co. in New York who follows the company, said Puma could pursue a deal similar to Cougar’s. Schmidt said worldwide sales of neratinib could exceed $600 million by 2020 if approved by regulators.

However, Puma could end up marketing the drug on its own, said Tekla’s Gentile, or through a partnership.