Sexual-misconduct allegations against Steve Wynn are threatening to derail Wynn Resorts Ltd.’s lucrative casino project in Massachusetts as regulators revisit a contentious debate on the company’s license to operate in the state.

Massachusetts gambling commissioners are set to meet Wednesday to discuss the allegations against Mr. Wynn, including a $7.5 million settlement paid in 2005 to a manicurist who told people at the time that Mr. Wynn forced her to have sex with him. State gambling commissioners can revoke the Wynn license...