LOS ANGELES (AP) — Shares of Puma Biotechnology Inc. were volatile on Wednesday after the company said it reached an agreement with regulators on the design of a late-stage trial of its drug neratinib as a treatment for breast cancer.

Puma's agreement with the Food and Drug Administration covers the design, goals, and analysis of the trial. Puma said it will study neratinib as a treatment for breast cancer that has metastasized in patients who have failed at least two other treatments. The trial will compare a combination of neratinib and Roche's cancer drug Xeloda to a combination of Xeloda and GlaxoSmithKline PLC's Tykerb pill.

The company said it will start enrolling patients around 600 patients in March or April in the trial. It will measure how long the patients live after treatment, and will also measure their progression-free survival — or how long the patients live before they die or their disease starts to advance again.

Puma does not have any approved products, and neratinib is its most advanced experimental drug. It is a type of protein blocker that appears to target proteins associated with aggressive forms of breast cancer.

Shares of the Los Angeles company rose about 5 percent in early trading, then fell around 7 percent. At the close the stock was down less than 2 percent at $24.15.

Puma Biotechnology completed its IPO in April, and its stock has traded between $8 and $27.95.