Oro Valley’s Ventana Medical Systems is under new leadership after its president and CEO stepped down recently.

Mara Aspinall, who had headed Ventana and the tissue-diagnostics division of Swiss parent Roche since 2011, resigned in late June to pursue interests outside of the company, Ventana spokeswoman Jacqueline Bucher said.

Daniel L. Zabrowski, formerly head of Roche’s gene-sequencing division in Pleasanton, California, was named president of Ventana to replace Aspinall, Bucher said. He also is global business area head of tissue diagnostics and sequencing solutions for Roche.

Aspinall could not be reached for comment.

Ventana was founded in 1985 by University of Arizona pathologist Dr. Thomas Grogan, who commercialized his idea for an automated instrument to rapidly prepare tissue samples for pathological analysis. The company went public in 1996 and had about 700 employees by 2008, when it was acquired by Roche Holdings AG in a deal worth $3.4 billion.

Since its acquisition by Roche, the company has made a major move into so-called companion diagnostics, which are designed to confirm the presence of a specific biological marker to help physicians select effective therapies based on a patient’s genetic characteristics.

Zabrowski, who holds a doctorate in organic chemistry from Indiana University, joined Roche Pharmaceuticals in 1995 as vice president of drug regulatory affairs.

He served in various executive positions over drug regulatory affairs and pharmaceutical development before he was named global head of Roche’s Pharma Partnering division in 2007. Zabrowski became global business area head of Roche’s Applied Science division in 2012 and has led Roche’s sequencing unit since last year.

Before joining Ventana in 2011, Aspinall was founder, president and CEO of On-Q-ity, a now-defunct startup diagnostics company focused on circulating tumor cell technology. Before that, she was with Genzyme Corp. for 12 years, holding senior executive positions including president of Genzyme genetics and pharmaceuticals.

Aspinall was a co-founder of Dx Insights, a nonprofit group devoted to educating doctors and other health-care stakeholders on the value of diagnostics in improving patient care and reducing treatment costs.

Contact Assistant Business Editor David Wichner at dwichner@azstarnet.com or 573-4181.

Senior reporter covering business and technology for the Arizona Daily Star/Tucson.com