WASHINGTON (Reuters) - U.S. biotechnology company Clovis Oncology Inc and its Chief Executive Patrick Mahaffy and former CFO Erle Mast, will pay more than $20 million to settle charges of misleading investors about the efficacy of a cancer drug, the top U.S. securities regulator said on Tuesday.

The Securities and Exchange Commission said they agreed to the settlement without admitting or denying the allegations, and that the settlements are subject to court approval.

According to the SEC, Clovis continually told investors that its drug, Roci, caused targeted tumors to shrink in 60 percent of patients, when data showed it had actually caused tumor shrinkage in 42 percent of patients.

Once Clovis disclosed the true efficacy rate at the end of 2015, its stock price dropped about 70 percent, the SEC added.