Abstract
Background: We investigated risks associated with performing pre-freezing preparation of cells harvested for chimeric antigen receptor (CAR) T-cell therapy within a clean booth using non-sterile clothing.
Methods: An Air Barrier Booth® (ABB, Dai-Dan Co., Ltd.), was installed in a general hospital environment. Two operators conducted cell preparation inside a safety cabinet within the ABB, wearing sterile gloves but non-sterile sandals, gowns, masks, and caps, which were reused for the same lot. Sixty-five procedures for tisagenlecleucel (Kymriah®) were examined for airborne falling bacteria at eight locations around the ABB, and sterility tests were performed on pre-freeze products.
Results: Cleanliness during non-operation met Grade A standards inside the safety cabinet and Grade B in the work area. Positive rates of falling bacteria during the operation were 2% inside the safety cabinet, 0% upstream of the ABB, 13% in the work area downstream of operators at workbench height, 26% at floor level, and 43% in the support area. Various bacteria were detected. All pre-freeze products were culture-negative, with no manufacturing failure due to contamination.
Conclusions: Due to the frequent presence of airborne bacteria downstream of operators, special attention should be paid to processing cellular material in a clean booth with non-sterile clothing.
