July 25 (Reuters) - Pharmacy benefit manager Express Scripts Holding Co said on Tuesday that a new contract with biggest customer Anthem Inc would be on terms significantly less favorable for the company.

Express Scripts said in April that health insurer Anthem, which has sued the company in March last year over claims of being overcharged, was unlikely to renew its contract after it ends in 2019.

Anthem subsequently said that it would consider Express Scripts and all other interested parties as it looked to sign a new contract.

"If we do enter into new contract with Anthem, it would be on terms significantly less favorable to us than current contract," Express Scripts said in a regulatory filing. (http://bit.ly/2vH180q)

Express Scripts shares fell 1.85 percent in extended trading on Tuesday.

Express Scripts said the Anthem contract generated about 19 percent of total consolidated revenues for the quarter ended June 30.

Express Scripts also reported better-than-expected second-quarter earnings. The company forecast a third-quarter profit above Wall Street estimates. (Reporting by Akankshita Mukhopadhyay in Bengaluru; Editing by Lisa Shumaker)