Adequate and Predictable Stem Cell (SC) Collection and Low Incidence of Neutropenic Fever (NF) with Cyclophosphamide (C) and G-CSF Mobilization in Multiple Myeloma (MM) : A Single Center Analysis

Background

G-CSF alone or C with G-CSF are most commonly used for SC mobilization in MM. The use of C can improve the efficacy of mobilization but is associated with increased neutropenia. It remains largely unclear how dose levels of C in mobilization quantitatively influence the CD34 yield and time to collection; as well as how these outcomes were influenced by patient's age. We evaluated the efficacy and neutropenia secondary to C with G-CSF in MM patients undergoing SC transplantation. Subgroup analysis was done comparing patients greater than 70 years and younger.

Methods

We retrospectively reviewed charts of all patients with MM who mobilized using C with G-CSF at UMass Memorial Medical Center from January 2009 to June 2014.

Results

Fifty-six patients were identified from the stem cell transplant database. There were 36 males (64%) and 20 females (36%).  Median age was 62 years (range 43 - 79). The median C dose received was 2548 mg/m2 (range 1318 - 4018mg/m2). The median total CD34 collection was 15.07 x 10e6/kg (range 2.71-113). Median time from C infusion to SC collection was 10 days (range 10-16). Number of days required for collection was 1(n=40), 2 (n=14) and 3 (n=2). Three patients received plerixafor prior to day 2 collection. Median days of documented neutropenia was 1 (range 0-6). Only 3 (5.3%) patients were hospitalized for NF requiring intravenous antibiotics. Optimal collection for two transplants (>10x 10e6 CD34/kg) was achieved in 43 (77%) patients.

12 patients (21%) were over age 70 years. In comparison with the younger patient, they were noted to receive lower median dose of C (1988mg/m2 vs. 2714mg/m2, p value 0.0326). They were also noted to collect slightly lower CD34 (14.1e6/kg vs. 15.85e6/kg, p value 0.0974). There was no significant difference in days to SC collection or number of days of neutropenia.  

Conclusion

Our retrospective analysis showed that duration of neutropenia does increase significantly with increase in C dose, yet with an overall low NF hospitalization rate. Higher C dose usage led to longer time to collection.

There was no significant difference in CD34 yield, neutropenia, or NF hospitalization in patients >70 years. C+ G-CSF is an effective method of mobilization as proven by optimal collection

Table 1

C dose (mg/m2)	<2000mg/m2	2000-3000mg/m2	>3000mg/m2	p-value
Median age in years (range)	64.5 (44-79)	62.5 (43-77)	60.5 (48-68)	0.5905
Number of Patients	18	22	16	-
Medican C Dose in mg/m2 (range)	1750 (1318-1983)	2584 (2001-2994)	3788 (3033-4018)	0.0001
Median Total CD34/Kg in 10e6 (range)	14.15 (6.89-39.7)	15.72 (2.71- 36.6)	16.10 (5.27 – 113)	0.6717
Days to SC collection (range)	10 (10-14)	10 (10-13)	11 (10-16)	0.0031
Median days of documented neutropenia (range)	1 (0-4)	2 (0-6)	3 (0-6)	0.0003
Number of patients hospitalized for NF	0	1	2	0.2712