Erez Vigodman and the board of Israel’s Teva Pharmaceutical Industries – the world’s largest generics drugmaker – have announced that the chief executive, who has led the company since January 2015, has resigned with immediate effect. Vigodman has also stepped down from his position on the company’s board of directors.

Succeeding Vigodman in the CEO slot for an interim period will be the board’s chair, Yitzhak Peterburg. Sol J. Barer, who has been a member of the Teva board since January 2015, will take over as chairman. Barer was a founder of the biotechnology group at Celanese Corporation, later spun off as Celgene Corporation, and also served terms as CEO and later chairman of Celgene.

The Teva board is now searching for a permanent CEO. “I believe that now is the right time for me to step down,” Vigodman said in a statement. The company is currently reviewing its strategic priorities to improve the bottom line, with an immediate focus on realizing the cost synergies and strategic benefits of the Actavis Generics acquisition last year. In the past, it has has projected it could carve out $1.4 billion in synergies by 2019.

The drugmaker has come under significant pressure due to the expiration of important patent for the multiple sclerosis treatment Copaxone, which accounts for an estimated 16% of sales and over 40% of operating profit. Last week, its shares tumbled on news of a lost patent challenge in a US District Court in Delaware. The court, which rejected four of the patent infringement claims covering a 40 mg injection to be administered three times weekly, said the claims were invalid, as they appeared to be an attempt to lock out generic competition. Teva said it would appeal.

Analysts believe that, as a generics producer itself, the Tel Aviv-based company still has opportunities that could benefit Copaxone.  For example, it could generate “billions of dollars in revenue” by developing complex biosimilars to expensive biologic drugs that are losing patent protection. Teva is also working on new brand-name drugs with blockbuster potential, including therapies for big-value indications such as chronic pain, migraine, and asthma. 

Also last week, the drugmaker announced that the US Food and Drug Administration (FDA) has approved two products for adolescent and adult patients with asthma, AirDuoTMRespiClick (fluticasone propionate and salmeterol inhalation powder) and ArmonAirTM RespiClick (fluticasone propionate inhalation powder).