Single Dose Plerixafor and Multi-Day Apheresis: Skip Dosing Enables Cost Efficient Mobilization for Patients Close to Achieving Treatment Goals

Plerixafor (P) is highly effective at mobilizing peripheral blood stem cells.  Most centers, including our own, have an algorithm that utilizes P in patients who are predicted to have poor collections using G CSF alone, based on peripheral blood CD34 count.  These algorithms are essential given the high cost of P and the inability to determine which patients will collect poorly using clinical parameters alone. 

Previous studies have shown that the high cost of P is justified based on fewer apheresis days required.  However when patients require 2 or more days of P the costs can become prohibitive. 

To alleviate the need for additional days of P we piloted an approach where patients who were close to achieving their target collection goal after the first day of P continued their G CSF, but without an additional dose of P.  Minimum accepted collection goals were 2 x 10⁶ CD34/ Kg for NHL patients and 4 x 10⁶CD34/ kg for MM patients.

From April 2012 through April 2014 170 patients underwent an autologous transplant.  Fifty (29.4%) ultimately required P to mobilize adequate numbers of cells.  Ten patients (7 NHL, 3 MM) were judged close to their preset target collection goal after their first dose of P.  These patients were collected the following day without  an additional dose of P.

 

	Median Pre CD 34 /uL	Median CD34/ kg Initial Collection	Median CD34/ kg Second Collection	Median % of Initial Collection	Days to ANC >0.5 x109/L	Days to Plt >50 x109/L
NHL (n=7)	2.1 (1.5-6.2)	1.5 (1.27-1.68)	0.68 (0.27-1.96)	41% (21-114)	11 (10-12)	16 (11->28)
MM (n=3)	3.1 (3.1-5.7)	3.01 (1.85-3.77)	1.51 (1.11-3.01)	60% (40-85)	11 (9-12)	14 (13-14)

As shown in Table 1, the median peripheral blood CD34/uL count prior to collection was 2.1 for NHL and 3.1 for MM.  The median CD34 x 10⁶ /kg collected the day following the dose of P was 1.5 (NHL) and 3.01 (MM).  On the second day of collection without P, the median CD 34 x 10⁶collected was 0.68 (NHL) and 1.51 (MM).   All patients achieved their target goals and were able to successfully proceed to transplantation.  The median percentage of the original collection is 40 and 60% respectively for NHL and MM.  All patients engrafted with similar times to patients not requiring P, or who had a successful collection with a single apheresis.

It appears that in patients who are close to achieving their target dose, that the strategy of omitting the second dose of P can successfully allow collection of sufficient cells to permit autologous transplant with appropriate engraftment times. In our population 20% of the patients who received P fell into this category.  With a cost of approximately $ 7000 per patient dose, the cost savings per 100 patients transplanted would be approximately $42,000.  Such an approach clearly can minimize the costs associated with stem cell mobilization and collection without any difference in the clinical outcome.