"As part of those discussions, the Reporting Persons have indicated their belief that based on their experiences and interactions with the Issuer, it is in the best interests of the Issuer and its shareholders that the board undertake measures to effect and facilitate the imminent retirement of Harvey Berger as CEO of the Issuer and that any settlement of a proxy contest must include the CEO's retirement," Sarissa wrote in the filing. "Unfortunately," Sarissa said, it has "not been able to reach a settlement."
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Ariad confirmed receipt of the filing Friday, and declined to comment further. Sarissa's Denner didn't immediately return a call seeking comment.
Ariad shares rose 6.5 percent on Feb. 13 after CNBC reported Sarissa's plans. It was up more than 11 percent Friday afternoon.
Berger founded Ariad and has led the company since 1991. The drugmaker's shares have come under pressure in recent years after its only approved medicine, the cancer drug Iclusig, was pulled from the U.S. market in late 2013 over safety concerns. It was back on shelves two months later, with tighter restrictions on its use. As of Thursday's close, Ariad's stock was down 16 percent in the last 12 months, compared with a 29 percent gain for the Nasdaq Biotechnology Index.
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Still, some question whether replacing the CEO will speed the shares' recovery.
"I don't know what someone who replaces Harvey Berger would do that's any different than what they're doing right now," JMP Securities analyst Mike King said in a Feb. 13 telephone interview. "This is going to be a process; the data are the data."
Ariad is conducting multiple clinical trials to better understand Iclusig's safety and efficacy profile, aiming to expand its use to more patients.
"Can anybody make them go faster?" King asked. "Maybe a little bit, but how much faster, and what would be accomplished?"