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Ironwood CEO steps down months after clinical trial failure

Mallon says he will ‘pursue another leadership opportunity’ following disappointing results for an experimental drug to treat acid reflux.

Ironwood Pharmaceuticals had success with Linzess, a drug that treats irritable bowel syndrome.
Ironwood Pharmaceuticals had success with Linzess, a drug that treats irritable bowel syndrome.Craig F. Walker/Globe Staff

Mark Mallon will step down as chief executive of Ironwood Pharmaceuticals next month “to pursue another leadership opportunity,” the Boston firm announced Monday, less than two years after he took the top job.

Ironwood, which specializes in treatments for gastrointestinal diseases, suffered a major setback in September. The company said it was laying off 35 percent of its staff ― about 100 employees ― and shelving an experimental acid reflux drug after it failed to reduce the severity of heartburn in a key clinical trial.

The experimental medicine was the only one under development in Ironwood’s pipeline. Another drug that would have treated abdominal pain associated with irritable bowel syndrome was discontinued following another trial failure in May.


“My decision to leave Ironwood was not easy, but I believe the chance to pursue multiple passions of mine is the right decision for me and my family,” he said in the company’s news release.

Ironwood’s board named Thomas McCourt, the firm’s president, as interim chief executive. Mallon’s departure takes effect March 12.

Founded in 1998, Ironwood developed Linzess, a drug that treats irritable bowel syndrome accompanied by constipation, and brought it to market in 2012 with a corporate partner later bought by Allergan.

Mallon joined Ironwood as chief executive in April 2019 after 24 years as AstraZeneca, the British-Swedish drug giant. He succeeded Peter Hecht, who cofounded Ironwood and had served as its only chief executive.

Hecht left to become CEO of Cyclerion Therapeutics, a Cambridge spinoff focusing on novel treatments for serious diseases of the central nervous system, particularly cognitive disorders.

Jonathan Saltzman can be reached at jonathan.saltzman@globe.com.