It seems the context of this phrase like it refers to a letter being sent to update the KAMC (King Abdulaziz Medical City) regarding the progress or changes in a control upgrade project. The translation of this part of the phrase into Arabic:
"control upgrade project" = "مشروع تطوير نظام التحكم"

The translation of the complete phrase would be:
"Update letter to KAMC for control upgrade project."
=
"رسالة تحديث إلى مدينة الملك عبد العزيز الطبية بخصوص مشروع تطوير نظام التحكم"

Clarification!
The phrase "control upgrade project" refers to a project which aims to improve an existing control system. In this context, a control system for example monitoring, regulating, or managing equipment and resources.

In the case of the KAMC (King Abdulaziz Medical City), this control upgrade project might involve updating or modernizing the systems responsible for managing the medical city, such as patient care or resource allocation. The goal of the project would be to increase efficiency and improve performance, or it can even be related to ensure better compliance with regulations and standards.