The US FDA has rejected Bluebird Bio’s Biologics license application (BLA) for ide-cel and asked for more details of how the candidate blood cancer therapy is made.

Bluebird announced receipt of a “refuse to file letter” (RTF) in an SEC filing on Wednesday.

The firm said the US Food and Drug Administration (FDA) asked for supplemental information on validation and control processes used in lentiviral vector and drug product manufacturing processes for Idecabtagene vicleucel (ide-cel), an investigational chimeric antigen receptor (CAR) T cell therapy targeting B-cell maturation antigen (BCMA).

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Bluebird CEO Nick Leschly told analysts the agency has asked for more detail in the Chemistry, Manufacturing, and Controls (CMC) section of the ide-cel BLA.

“The FDA advised Bluebird and [partner Bristol-Myers Squibb] that it has reviewed the BLA submission and is asking for supplemental CMC reports regarding more details documentation of the manufacturing processes.”

Despite the RTF letter Leschly remained positive. He said, “These are things, quite honestly, almost all of which are on hand and we need to assemble and put together.”

Leschly added that Bluebird and BMS intend to resubmit the ide-cel BLA by the end of July along with a request for priority review.

Documentation not data

Leschly’s comments were echoed by chief manufacturing officer Derek Adams, who said, “The requests were for documentation of validation and overall process understanding.

Adams added that the requests are “not similar to the potency assay work we’ve discussed in the past,” he added.

In February, Bluebird put back its target completion date for the rolling BLA for LentiGlobin – its candidate β-thalassemia therapy – after the FDA had asked for more information about release assays for the product.

Manufacturing rejig

News of the RTF letter came just days after BMS agree to pay Bluebird $200 million to buy itself out of ex-milestone and royalty payments for ide-cel and a second BCMA-directed CAR T immunotherapy called bb21217.

Under the revised deal BMS will also take responsibility for making the lentiviral vectors (LVV) needed to manufacturing ide-cel for all markets except the US.

Bluebird plans to make vectors to support the product in the US and is building a manufacturing facility in Durham, North Carolina for the production of lentiviral vector (LVV).

Krishnan Viswanadhan, global cell therapy franchise lead for BMS said, “This amended partnership allows Bristol Myers Squibb to leverage our global manufacturing capabilities and consolidate all responsibilities outside the US.”