(Reuters) - Cigna ( CI ) beat Wall Street estimates for third-quarter profit on Thursday, as its unit that runs the pharmacy benefit management business added new clients and saw strong demand for close copies of a blockbuster arthritis drug.

The conglomerate started distributing close copies of AbbVie's arthritis drug, Humira, in June, at no out-of-pocket cost to patients using its specialty pharmacy Accredo.

Cigna ( CI ) expects the biosimilar opportunity to go beyond Humira and sees an additional $100 billion of annual specialty drug spend to be subject to biosimilar and generic competition in the U.S. by 2030.

Pharmacy benefit managers are companies that handle prescription drug benefits for health insurance companies, large employers and Medicare prescription drug plans - a group often referred to as payers.

Total adjusted revenue at the Evernorth healthcare services unit rose 36% to $52.64 billion.

For the quarter ended Sept. 30, the company posted adjusted profit of $7.51 per share, beating analysts' estimates of $7.20 per share.

(This story has been corrected to say that Evernorth's revenue rose to $52.64 billion, not $52.63 billion, in paragraph 5)