"By streamlining the structure of the Board of Management, we are optimizing the allocation of responsibilities and contributing to the company's ongoing efficiency program," Werner Wenning, chairman of the non-executive supervisory board, said in a statement on Tuesday.
Malik is responsible for innovation as well as the Asia Pacific region while Klusik holds the position of labor director and is responsible for technology and sustainability.
The company will continue to push for innovation and to develop its network of partnerships, Chairman Wenning added.
Bayer said last year it would lean more strongly on external firms and institutions for a better drug development pipeline, which most analysts regard as too thin to make up for an expected decline in revenues from its two pharma bestsellers from about 2024.
In late 2018 Bayer also unveiled plans to slash 12,000 jobs, about one in 10 of its global work force, and set out on an asset divestment campaign that included its animal health division.
Bayer is seeking to reduce debt after the $63 billion takeover of seed maker Monsanto last year. Its share price has been depressed by U.S. litigation over an alleged cancer-causing effect of Monsanto weedkillers.
The company has reaffirmed the product is safe to use, citing backing by health regulators but analysts on average expect a litigation settlement of more than $10 billion.
Responsibility for innovation would be split among divisional heads of Bayer's pharmaceuticals, crop science and consumer health businesses.
About a year ago, Klusik, Bayer's labor director and board member responsible for technology, was given a contract extension for one year until the end of 2019.
Sources familiar with the company said at the time the extension of Klusik's contract had been in doubt because drug production at Bayer's Leverkusen plant in Germany was found to be substandard by U.S. regulators in February and this fell under his remit.
But Bayer hung on to him to have an experienced head of personnel oversee an overhaul of the research and development operations.
Bayer Chief Executive Werner Baumann will take over as head of personnel next year, adding the title of labor director.
(Reporting by Ludwig Burger; Editing by Michelle Martin)
By Ludwig Burger