Novartis AG said Susanne Schaffert, president of its unit Advanced Accelerator Applications SA, will become CEO of Novartis Oncology, effective Jan. 1.

Schaffert has been with the Swiss pharmaceutical giant for over 20 years and has held leadership roles in the oncology unit for the past six years.

She will replace Liz Barrett, who will step down as CEO of the oncology unit, effective Dec. 31.

Barrett, who became head of Novartis Oncology on Feb. 1, said she is leaving because her family will be unable to relocate to Basel, Switzerland, where the unit is based. Barrett will join a U.S.-based biotechnology company as CEO.