expression, suru verb (irregular)
be led by; be headed by
Used in the pattern ～を筆頭とする to indicate that a person or group is at the head of a list or organization. Often found in formal or written contexts.
See also: 筆頭
彼を筆頭とするチームがプロジェクトを進めている。
The team headed by him is advancing the project.
この分
In this field, a group of companies led by Company A is leading the market.