Hudson, who is British, will take over on Sept. 1, Sanofi said, confirming a Reuters report published on Thursday and marking the latest move by a Novartis executive to a competitor.

Shares in Sanofi were up 4.95 percent at 1050 GMT, leading gainers on the Paris benchmark CAC 40 index.

"As an external, and non-French hire, Paul Hudson will be seen as a step in the right direction," said Graham Doyle, an equity analyst with Liberum.

Hudson, 51, has been CEO of Novartis Pharmaceuticals, one of the Swiss company's three main divisions, since 2016.

Earlier, he worked at Schering Plough and AstraZeneca.

Novartis named Marie-France Tschudin, president of Novartis unit Advanced Accelerator Applications (AAA), to replace Hudson with immediate effect.

"Hudson has been chosen because of his reputation. He is known as a solid manager and has digital expertise relating to pharmaceuticals," a source familiar with the decision said on Thursday.

Hudson's departure follows the exit of Samit Hirawat, head of oncology drug development, who is to become chief medical officer at Bristol-Myers Squibb in a move announced on Wednesday.

RESHAPING SANOFI

Brandicourt was hired in 2015 to help to revive the fortunes of Sanofi and has been reshaping the business.

Under his tenure, the company swapped its animal health unit with Boehringer Ingelheim for the German company's consumer healthcare operations in a $20 billion deal. Sanofi also sold its European generics arm for 1.9 billion euros ($2.1 billion) to private equity firm Advent International.

New launches such as eczema treatment Dupixent, cost-cutting measures and new priorities in research and development enabled Sanofi to return to profit in the second half of last year after a series of disappointing quarters.

Brandicourt's teams, however, failed to land two strategic acquisitions, losing out to Pfizer on buying California-based cancer specialist Medivation in 2016 and failing to acquire Swiss biotech company Actelion, which was bought by Johnson & Johnson in 2017.

NEW MEDICINES

At Novartis, Tschudin takes over a main drugs business with $35 billion in annual sales and a stable of medicines including newly approved $2.1 million-per-patient gene therapy Zolgensma, the world's most expensive one-time therapy, for children with spinal muscular atrophy.

Novartis is being watched for how successfully it can roll out Zolgensma as well as several other new medicines including Mayzent in a crowded multiple sclerosis field.

Tschudin, a Swiss citizen who speaks six languages, joined Novartis in 2017 after working at Celgene where she ran its Hematology-Oncology business for Europe, Middle East and Africa.

Answering to Chief Executive Vas Narasimhan, Tschudin's brief will be continuing the Swiss drugmakers' push into cell and gene therapy for rare diseases, while also building out a diverse portfolio of medicines for heart disease, immunology, liver disease, neuroscience and respiratory ailments.

"Marie-France has a strong record of accomplishments in driving commercial excellence and a culture of inclusiveness and integrity," Narasimhan said.

(Reporting by Matthias Blamont in Paris and John Miller in Zurich; Additional reporting by Laetitia Volga ; Editing by Jason Neely/Keith Weir)

By Matthias Blamont