ImmunityBio was hit with a complete response letter from the FDA for its bladder cancer prospect, sending the California-based company’s stock into a steep slide Thursday.

The company’s stock fell more than 50% in overnight trading after it announced in a Securities and Exchange Commission filing Wednesday that it received a CRL from the agency on its application for its drug Anktiva in combination with a vaccine mainly used against tuberculosis, Bacillus Calmette-Guérin. The treatment is designed for patients with BCG-unresponsive, non-muscle invasive bladder cancer.

Shares in the overnight session tumbled to $3.39 from Wednesday’s closing price of $6.22.

“The deficiencies relate to the FDA’s pre-license inspection of the company’s third-party contract manufacturing organizations,” ImmunityBio said in the filing. “Satisfactory resolution of the observations noted at the pre-license inspection is required before the [application] may be approved.”

ImmunityBio said it has requested a meeting with the FDA to address the agency's concerns. The company said it will “diligently address and resolve the issues identified and seek approval as expeditiously as possible.”

Last October, the company was forced to backtrack on hiring for its New York facility. ImmunityBio had pledged to hire 300 employees at the site, but instead announced it planned to let go of 38 workers by the end of the year.

At the time, it said the cuts were due to “economic” reasons. About 50 people were employed at the site before ImmunityBio took it over from Athenex earlier in 2022.