A single leukemia cell inadvertently got mixed in with a batch of a patient’s immune cells that were being manufactured into a CAR-T cell therapy and it acquired resistance to the treatment with deadly results, University of Pennsylvania researchers reported.

Chinese manufacturer Cellular Biomedicine has been enlisted to make Novartis’ $475,000 gene-modifying cancer treatment Kymriah as the Swiss drugmaker intends to win approval for the therapy in the world’s most populous country.

Novartis was granted fast-track reviews of its cell therapy Kymriah for blood cancers in the United States and Europe.

Novartis submitted its cell therapy Kymriah for European approval in two forms of blood cancer, seeking to expand the use of the new treatment.