Regulation of Companion Diagnostics in the US and in IVDR

The IVDR redefines and introduces a new conformity assessment for companion diagnostics (CDxs), upclassifying them to class C.
Companion diagnostics now have stricter performance requirements and the need for clinical evidence.

More importantly, there is now a link between the CDx assessment by a Notified Body and the corresponding medicinal product’s assessment by a medicine Competent Authority or the European Medicines Agency.

Within this framework, and although there has been an effort to align the definition of CDxs with the one accepted by the FDA, the overall regulatory pathway is somewhat different on the two sides of the ocean.
See here the comparison.