Cost and Utilization Of Stored Autologous PBSC To Support Tandem ASCT In MM Patients In The Era Of Novel Agent Therapy
Authors: Phipps Colin , Linenberger Michael L. , Green Damian J. , Palanca-Wessels M. Corinna , Becker Pamela S. , Connelly-Smith Laura S. , Burwick Nicholas , Klippel Zandra K. , Bensinger William I. , Holmberg Leona , Libby Edward N. 
Published: October 2019

Introduction
Historically, autologous stem cell transplantation (ASCT) for multiple myeloma (MM) improves overall survival (OS) compared to conventional chemotherapy alone. Before the introduction of novel agent therapy, tandem ASCT, defined as a second ASCT within 180 days of the first, was an important option for suboptimal responses after an initial ASCT and thus collecting adequate peripheral blood stem cells (PBSCs) for 2 transplants has been considered standard of care. However, the role of tandem transplants is being challenged by novel agent maintenance strategies. Considering this changing landscape of MM therapy, we sought to evaluate the current PBSC collection and storage practices that set the CD34+ cell dose goal to be sufficient for 2 transplants.

Methods
We obtained clinical, PBSC collection and storage data on MM patients who underwent ASCT from 1993 to 2011 from the Autologous Transplant and Cellular Therapy Laboratory databases at the Fred Hutchinson Cancer Research Center. We determined frequencies and trends of all second ASCTs, including tandem, costs involved in PBSC collection, storage, and utilization of the product that remained cryopreserved for a second ASCT. Cell dose target at our center is 5 x 106 CD34+ cells/kg/transplant. To analyze trends over time, we divided the sample into groups of 3 or 4 year periods. Collection and cryopreservation costs for second ASCT were calculated by first determining the number of days required to collect sufficient PBSC for one ASCT, then the number of additional days to complete the actual collection, and the cumulative costs of long-term storage in our facility. Cost was estimated per July 2012 charges: 1 day PBSC collection $3,016, 1 day processing for cryopreservation $5,955, 1 year storage fees $408 ($34/month). The cost of mobilization chemotherapy and growth factors were not included.

Results
From May 1993 to June 2011, 889 MM patients underwent PBSC collection and ASCT (111 of 1000 excluded due to incomplete records). Median total PBSC collection days was 2 (range 1 – 10) with median yield of 13.18 x 106/kg CD34+ cells. Median days to collect sufficient cells for one ASCT was 1 day (1 – 9) and 383 patients collected adequate cells for 2 ASCTs after 1 apheresis procedure. Of 889 patients, 135 underwent a second ASCT within a median 14 months (2.5 – 113) of the first. Number of second ASCTs per time period: 1993 to 1995 – 9 of 39 MM patients undergoing ASCT (23%), 1996 to 1999 – 18 of 100 (18%), 2000 to 2003 – 15 of 162 (9%), 2004 to 2007 – 62 of 251 (25%), 2008 to 2011 – 31 of 337 (9%). Fifty patients underwent tandem ASCTs and these accounted for 89%, 72%, 7%, 24%, and 42% of all second ASCTs during the respective periods; the other 85 occurred > 6 months after the first. Number of additional days and associated costs to collect and store PBSC for a second ASCT: 5 days ($44,855), n=1 patient; 4 days ($35,844), n=2; 3 days ($26,913), n=10; 2 days ($17,942), n=41; and 1 day ($8,971), n=211. 637 patients had unused PBSC that remained in storage for ≥ 1 year, with a rising trend over time: 1993 to 1995 – 7 (1%), 1996 to 1999 – 65 (10%), 2000 to 2003 – 77 (12%), 2004 to 2007 – 185 (29%), 2008 to 2011 – 303 (48%). Duration of storage was < 2 years for 34, 2 to 5 years for 346, and > 5 years for 257 patients. Median PBSC storage time was 40 months. PBSC products from 260 patients were discarded (or sent to repository), after a median storage of 54 months, for the following reasons: 5 had allogeneic transplant, 74 were alive and possibly concerned about costs and/or the unlikely need for a second ASCT, 3 had cell viability issues, and 178 patients had died.
From January 2009, some patients received plerixafor to achieve the collection goal for 1 ASCT. Its cost was not considered additional. Estimated average cost for PBSC collection, cryopreservation and storage was at least $20,065.96/person and at least $6718.11/person was spent to collect and store PBSC for a tandem ASCT that was never performed.

Conclusions
Approximately 70% of patients had PBSC products that remained unused and in prolonged cryopreservation after the first ASCT. Estimated cost for collection and storage of PBSC beyond that needed for a single ASCT accounted for roughly 1/3 of total costs. This conventional practice should be reconsidered in view of rising treatment costs, the evolving role of novel agents in maintenance therapy, and the deeper responses achievable with novel agents prior to first ASCT, thus reducing the need for tandem ASCT.

Disclosures:
No relevant conflicts of interest to declare.