Background/Case Studies: A community hospital-based cancer center in a rural state established an adult autologous hematopoietic stem cell transplant program in 2021, including a new cellular therapy laboratory (CTL) to cryopreserve and store cells. A cryopreservation procedure was developed to minimize contamination risk and reduce product volume cryopreserved. This study reviews product data and patient outcomes during the first 17 months using this protocol.
Study
Design/Methods: In brief, donor plasma was expressed to achieve a targeted concentration of 3.0 to 4.0 x 10^8 total nucleated cells (TNC) per mL. A sterile connection device is used to maintain a closed system until cells are ready for addition of a commercial U.S. Pharmacopeia (USP)-grade intracellular-like solution containing 10% dimethyl sulfoxide (DMSO) cryoprotectant (5% final DMSO concentration by volume) inside a biologic safety cabinet. Cooling was performed using a controlled rate freezer targeting a rate of -1oC per minute. Retrospective review of all autologous hematopoietic progenitor cell, apheresis (HPC,A) products collected from October, 2021 to March, 2023 was performed. Data reviewed included post-processing product characteristics, product sterility culture results, infusion adverse events, and time to engraftment.
Results/Findings: Fifty-two autologous HPC,A products were processed from 30 patients. The mean number of cryobags frozen per product was 3.4 (range 2-6). Mean cryobag characteristics showed: volume 50.4 mL per bag (range 34-66), DMSO volume 2.5 mL per bag (range 1.7-3.3), CD34+ cell dose 1.25 x 10^6/kg per bag (range 0.21-3.44), TNC concentration 3.49 x 10^8 cells/mL (range 2.44-3.99). Mean post-thaw testing from cryobags of 29 products showed: TNC recovery 100.3% (range 86.3-113.1), CD34+ cell recovery 81.1% (range 66.9-113.3), CD34+ cell viability 89.6% (range 83.0-95.2). Mean post-thaw testing from 32 cryovials (27 distinct products) showed: TNC recovery 90.3% (range 69.6-111.6), CD34+ cell recovery 74.1% (range 54.2-100.0), CD34+ cell viability 91.1% (range 82.6-96.6). Zero post-processing bacterial or fungal cultures were positive after 14 and 28 days, respectively. Cells from 49 products (123 cryobags) were administered to 29 patients (mean 4.4/patient); mean infusion CD34+ cell dose was 5.11 x 10^6/kg (range 2.69-8.67). Minor DMSO-related infusion reactions occurred in 5 recipients (17.2%); no other reactions were observed. The All recipients demonstrated neutrophil and platelet engraftment; mean time to engraftment for neutrophils was 11.1 days (range 9-13) and for platelets was 16.3 days (range 12-21). Zero post-processing bacterial or fungal cultures were positive after 14 and 28 days, respectively. Conclusions: Our HPC,A cryopreservation protocol results in sterile products, infrequent minor DMSO reactions, and successful engraftment following autologous transplant.
Importance of research: There are few publicly available protocols for HPC cryopreservation, or ones that utilize newer commercial USP-grade cryopreservation media. Our process and data may be useful to other community hospitals who may be asked if creating their own cell processing lab to support HSCT is feasible and can be successful.
