Peripheral Venous Access for Collection of Immune Effector Cells and Hematopoietic Stem Cells Is Feasible and Safe in Older Children and Young Adult Patients

Introduction: Collection of hematopoietic stem cells (HSC) for HSC transplantation (HSCT) and immune effector cells (IEC) for cellular manufacturing (e.g. CAR T-cells) in children and young adults has unique challenges. In order to maintain adequate flow rates, central venous catheters (CVCs) are often utilized at pediatric institutions. However, CVCs are associated with additional procedural risks (anesthetic complications, thrombotic events) and resource utilization (anesthesia, interventional radiology). In adults collection through peripheral venous catheter (PVC) access has become increasingly standard practice, but has not yet been routinely used in pediatrics. The aim of this study was to determine if it is feasible and safe to utilize PVC access in a select population of older children and young adults to reduce the need for CVC insertions.

Methods: All individuals undergoing HSC and IEC collections at our institution (patients and sibling donors) between February 2019 and July 2020 were considered for PVC collection if in the treating physicians assessment the patient would be able to tolerate the procedure (arms outstretched for up to 6 hours) and venous vessels were deemed suitable for an 18 gauge PVC. For blood return patients received either a second PVC (minimum 20 gauge) or if present their port/central line was used. For patients screened after April 2020, assessment by ultrasound was performed prior to the procedure to determine venous vessel size. All patients had topical analgesia applied prior to PVC insertion. All collections were carried out using the Continuous mononuclear cell collection (CMNC) protocol on an Optia apheresis device. Collection-related parameters such as demographics, collection efficiency (CE2), collection time, flow rate and product quality were collected.

Results: A total of 27 patients were screened for PVC collection from February 2019 until July 2020. The median age was 16.1 years (range 9.7-27.3) and median weight 67.7 kg (range 29.4-115.4). Ten out of 27 patients had ultrasound screening prior to collection on which one patient was deemed not suitable for PVC collection due to a venous anomaly. Cells were collected successfully by PVC in 24/26 (92%) of patients, 2/26 (8%) patients required CVC insertion after an unsuccessful PVC attempt due to inability to maintain an adequate flow rate. Average PVC collection flow rate was 50.3 ml/min (range 34-91) with median collection time of 244.5 min (range 87-397 min). Median collection efficiency (CE2) for CD3 cells was 59% (range 21-88), for CD34 cells 55% (range 28-69), product cell viability was 100%. Collection and product parameters were comparable to institutional collections performed utilizing CVCs. PVC collections were well tolerated, no patient had to stop the procedure due to discomfort or patient safety concerns.

Conclusion: PVC collection of IEC and HSC is feasible and safe in older children and young adults. Ultrasound screening prior to PVC insertion and collection attempt can reduce failure rate and streamline the collection process.