RQA GLP Committee
It depends where you are in the World. Some countries mandate that a Sponsor signature is required, (In some countries the COVID pandemic has meant this requirement has been waived). In the UK it is not mandatory, so check local regulations. However, it would be a good idea to have the Sponsor at least approve the amendment, as this indicates that they are supportive of the changes being made to the study. GLP states that the Study Director must have control of the study and therefore the sponsors agreement for the facility (and therefore the SD) to conduct the study should give the study director the permission they need to be able to conduct the study in the way they see fit.