Part 2: Work-in-Progress Papers ; International audience ; Cloud-based applications are built from services offered by distinct third-party cloud providers. Most cloud-related information (service properties such as price, availability, response time, etc.) can change at any time during application execution. Therefore, it is essential to support the adaptation of applications in such dynamic conditions in order to ensure that the cloud services currently provided to deployed applications adhere to the established requirements. In this paper we present an autonomous adaptation process for cloud-based applications by replacing a service by an alternative one that fulfills the application needs. We discuss the factors that trigger an adaptation in a Cloud Computing scenario and describe the adaptation process within Cloud Integrator, a service-oriented middleware platform for composing, executing, and managing services provided by different cloud platforms.