Gilead to acquire Calistoga in $375 million, plus milestones, deal

USA-based Gilead Sciences (Nasdaq: GILD) has signed a definitive agreement to purchase Calistoga Pharmaceuticals, a privately-held biotechnology company focused on the development of drugs to treat cancer and inflammatory diseases.

Gilead will pay $375 million to Calistoga, which could earn up to an additional $225 million if certain milestones are achieved. Gilead anticipates that the deal will close in the second quarter of 2011, subject to satisfaction of certain closing conditions, and plans to finance the acquisition through available cash on hand.

Calistoga has a portfolio of proprietary compounds that selectively target isoforms of phosphoinositide-3 kinase (PI3K). This pathway has been shown to be a central signaling pathway for cellular proliferation, survival and trafficking. The company’s lead product candidate, CAL-101, is a first-in-class specific inhibitor of the PI3K delta isoform. PI3K delta is preferentially expressed in leukocytes involved in a variety of inflammatory and autoimmune diseases and hematological cancers. CAL-101 is currently in Phase II studies as a single agent in patients with refractory indolent non-Hodgkin’s lymphoma (iNHL) and in combination with rituximab in treatment-naïve elderly patients with chronic lymphocytic leukemia (CLL). In addition to CAL-101, Calistoga’s product development pipeline includes other selective PI3K inhibitors that are in preclinical development, and may have application
in both oncology and inflammatory diseases.