Celltrion has come forward to explain reasons for the delayed approval of its Humira biosimilar, Yuflyma (CT-P17), in the U.S., saying there were some problems, but they have been solved now.

In a letter to shareholders published on its website Thursday, Celltrion said it has acquired a sales permit for Yuflyma from the European Medicine Agency and the Korean Ministry of Food and Drug Safety and is selling it while waiting for approval from the U.S. regulator.

“Faced with shareholders’ inquiries regarding the delayed approval by the U.S. Food and Drug Administration, we could like to explain the company’s position in this letter,” Celltrion said.

The company explained that the U.S. FDA pointed out a problem in its on-site survey of Celltrion’s overseas end-product manufacturing plant of Yuflyma and had to re-inspect the plant after rectifying the problem. However, this process did not end until the Biologics License Application (BLA) period, delaying the approval process, it added.

“Currently, the manufacturing facility has won the voluntary action indicate (VAL), a ‘passable grade,’ solving all problems,” it said. “We have confirmed that FDA would complete the final approval review by May through continuous consultation.”

According to Celltrion, VAL is the rating when a manufacturer voluntarily requests corrective action if unreasonable but not serious matters are found.

“The Celltrion Group has reached a patent agreement with the original maker and expects to sell Yuflyma in the U.S. from July,” it said. “Accordingly, we are stepping up preparation to launch the product in the U.S. market separate from the FDA’s approval process.”

Celltrion added that it acquired Celltrion USA in August for the successful direct sales of its drugs, securing the U.S. medicine product distribution license and network, and ushered in Thomas Nusbickel, who has rich experiences in distributing biosimilar products, as the CEO of its U.S. subsidiary.

“The delayed FDA approval is due to its overseas manufacturer and has nothing to do with Celltrion’s technological prowess,” the company said. “We ask for shareholders’ understanding for not providing a detailed explanation due to contractual reasons.”