U.S. sales of Remicade (ingredient: infliximab), the autoimmune disease treatment by Johnson & Johnson (J&J), plunged after facing fierce competition with biosimilar drugs such as Celltrion’s Remsima.

According to J&J’s third-quarter earnings announced on Tuesday, the U.S. sales of Remicade declined to $749 million, a 24.1 percent on-year drop.

It was the worst sales record for Remicade since Celltrion rolled out Remsima (U.S. brand name: inflectra) in November 2016. It is a disappointing result for Remicade, which used to sell over $842.7 million a quarter.

J&J attributed the sales decline to biosimilar competition. As the competition became severe, the price of Remicade, the original drug, had to go down. Remicade’s price reflecting discounts and rebates decreased by 6 to 8 percent last year, compared to a year earlier.

Celltrion and Samsung Bioepis entered the U.S. infliximab market with Remsima and Renflexis, respectively. From October, Remsima has been included in the priority list for United Health Care (UNH), one of the largest private insurers in the U.S. This raised expectations for increased sales of Remsima.

Industry watchers are paying attention to whether Remsima could break into the infliximab market where the original drug accounts for over 90 percent of the market share.

“As Remsima is registered as the top-tier 1 medicine equal to the original drug from the fourth quarter this year, it is expected to secure more than 20 percent of the market share in the U.S.,” said Koo Wan-seong, an analyst at NH Investment & Securities, in a recent report.

Celltrion aims to expand its U.S. market share by launching Remsima SC, the subcutaneous (SC) injection of the biosimilar. The company is testing Remsima SC in a phase-3 clinical trial. Remsima SC with a convenient injection formulation is considered a new drug in the U.S. If the drug arrives in the market, it could secure a favorable position in winning listing on the U.S. private insurance.