Bill Cosby's criminal sexual-assault case appears to be headed toward an evidence hearing after a Pennsylvania judge denied his latest effort to throw the charges out.

The judge who refused to dismiss the case this month has denied Cosby's appeal of that decision.

The 78-year-old TV star is accused of drugging and violating an ex-Temple University employee at his suburban Philadelphia home in 2004 and could get 10 years in prison if convicted. The defence insists Cosby had a promise from a previous district attorney he would never be charged over the encounter.

Montgomery County Judge Steven O'Neill found the evidence of such an agreement lacking. He says the issue doesn't warrant an immediate appeal that would delay the scheduled March 8 preliminary hearing.

A spokesman for Cosby's lawyers says it's unclear if they'll appeal to the Superior Court.