Sarissa Capital Management has landed a resounding win against Amarin, mustering shareholder support for its entire seven-person slate and the removal of the drugmaker’s chairman, despite opposing arguments from two influential proxy voting advisers.

Sarissa said in a statement Tuesday that it believes up to nearly 80% of shareholder votes were in support of its motions, describing the ballot results as a ‘‘huge landslide’’ proxy contest victory.

Amarin confirmed the special meeting outcome, citing preliminary voting results, and said its reconstituted board will be expanded to 15 directors led by a soon-to-be-named chair. New Amarin directors include Sarissa Head of Research Odysseas Kostas, and Patrice Bonfiglio, chief financial officer at the activist fund.

Sarissa, a 6% shareholder, focused its campaign on arguing that Amarin was poorly managed and led by a chairman, Per Wold-Olsen, who was more concerned about defending his seat than creating value for investors. For its part, Amarin said Sarissa would not be able to improve performance, adding that a win for the activist could actually harm the business.

Despite making its case in lengthy presentations and letters, Sarissa did not convince Glass Lewis or Institutional Shareholder Services (ISS). Both proxy advisers recommended a vote against Sarissa’s proposals.

‘‘While we sought a different outcome, the board and management team remain focused on executing Amarin’s strategy,’’ said Amarin in a statement Tuesday. ‘‘We will work constructively with the newly elected directors.’’

Amarin shares were up 6% in midday trading Tuesday.