A Value-Based Approach to Optimizing Peripheral Blood Progenitor Cell (PBPC) Mobilization and Collection for Autologus Hematopoietc Cell Transplantation (AHCT)

AHCT is a difficult and stressful procedure for patients and families. Optimal peripheral blood progenitor cell (PBPC) mobilization is important for successful AHCT, but multiple days of collection can be draining and time-consuming for patients and caregivers. Achieving the target CD34+ cell number in one collection day reduces time away for patients and caregivers and associated expenses, including lost wages and travel costs, thereby improving the patient experience.

We implemented and analyzed the impact of multiple innovations designed to make collections easier for patients. The efficacy of an algorithm using a lower threshold for plerixafor (Plx) administration than previously published based on the peripheral blood (PB) CD34 count on day 4, fixed (12 mg) versus standard weight-based dosing of Plx, use of adjusted (AdjBW) versus actual body weight (ABW) for calculation of the target dose of CD34+ cells to collect, and longer apheresis times to minimize collection day numbers were examined.

Data on 196 consecutive patients with plasma cell disorders (PCDs) or lymphoma undergoing PBPC mobilization and AHCT between March 2014 and May 2017 at the Levine Cancer Institute were analyzed. All patients received G-CSF 10 mcg/kg/d x 5 days. For patients with a white blood cell (WBC) count < 50K/uL on day 4, an extra evening dose of G-CSF was prescribed and either standard (0.24mg/kg) or fixed dose (12mg) Plx was administered if the PB CD34 count was < 35/uL for lymphoma patients or < 50/uL for PCD patients. The fixed dose was administered if a patient could be paired with another patient concurrently undergoing PBPC mobilization. The target for PCD patients was ≥ 10 million CD34+ cells/kg to permit two AHCT, and for lymphoma patients, 5 million CD34+ cells/kg for one AHCT. The impact of the use of AdjBW (ideal body weight (IBW) + 0.25 x (ABW- IBW)) to calculate the target number of CD34+ cells to collect, longer apheresis times, and higher number of blood volumes (BV) processed in minimizing collection days were also examined. US Census data were used to estimate patient income. Days of apheresis, run times, and collection and cryopreservation costs were also analyzed. Time to neutrophil and platelet recovery defined as an absolute neutrophil count (ANC) >500 for 3 consecutive days and sustained platelet count >20,000 were also assessed.

Analyses were conducted on collection parameters, count recovery, Plx use, and body weight. Statistical comparisons were made between the two Plx dosing paradigms. The frequency of Plx use and number of collection days were analyzed using Fisher's exact text. Analysis of variance (ANOVA) was used to analyze cell collection (by diagnosis), apheresis duration, BV, and body weight. Poisson regression was used to analyze days to ANC and platelet recovery.

Within the group of patients analyzed, 153 (78 %) had a PCD and 43 (22%) had lymphoma. Overall, 156 (80%) patients collected sufficient CD34+ cells in 1 day, 38 (19%) in 2 days, and 2 (1.0%) in 3 days, with 123 PCD patients (80%) and 33 lymphoma patients (77%) collecting in 1 day. The median duration time of apheresis was 6.7 hours and the median number of BV processed was 4.3. For PCD patients, a median of 10.7 million CD34+ cells/kg were collected, while for lymphoma patients, a median of 5.7 million CD34+ cells/kg were collected. A total of 172 (88%) patients received Plx, of which 153 (89.0%) received the standard dose. In the PCD group, use of AdjBW vs ABW resulted in collection on average of 1.3 million less CD34+ cells/kg (p=0.047), which had no impact on hematopoietic recovery. Using Plx, the cost savings realized by eliminating patient and caregiver travel expenses and lost wages and additional days of G-CSF, apheresis, and cryopreservation by reducing collection days from 3 to 1 is estimated to be $22,000, and reducing 2 days to 1 is estimated to be $7,700.

Collectively, these data demonstrate the value of our innovative approaches. Importantly, we had no mobilization failures. While dramatically lowering the threshold for Plx administration appears to be the most significant factor, longer apheresis sessions and use of AdjBW to calculate the CD34+ target dose also contributed to reducing the number of collection days.