NEW YORK (AP) — Astellas Pharma Inc. said Monday it signed a confidentiality agreement with OSI Pharmaceuticals Inc., which has rejected Astellas's hostile $3.5 billion, or $52 per share, takeover offer as too low.

Astellas has attempted to acquire OSI, which is based in Melville, N.Y., for more than a year and after repeated rejections filed suit to prevent OSI's board from interfering.

Astellas, which is based in Japan, made the hostile bid earlier this month.

Under the confidentiality agreement, OSI will provide Astellas with access to certain nonpublic information. And Astellas will not acquire any OSI shares, take any action on the lawsuit or file a proxy statement in connection with its annual meeting until 11:59 p.m. Eastern time May 15.

OSI focuses on treatments for cancer, diabetes and obesity. Most of its revenue comes from its lung and pancreatic cancer drug Tarceva, which it sells in partnership with Genentech, part of Roche.

Astellas said it has given OSI a full slate of independent directors to consider at its annual shareholder meeting. They include Michael A. Griffith, founder of drug development service provider Aptuit Inc., and Jill Kanin-Lovers, who has served on the board of drug maker Alpharma Inc.

OSI has contended that the nominees' mandate is to support the Astellas takeover.