Up to 30% of patients fail to collect minimum numbers of PBSC for ASCT, and up to 50% of patients fail to collect the optimal number. Plerixafor, a CXCR4 antagonist, in combination with G-CSF has shown superior results in mobilizing PB CD34+ cells in comparison to G-CSF alone for autologous PBSC mobilization in patients with NHL or MM. However, due to its high cost, we commenced a risk adapted algorithm for the utilization of plerixafor starting in Feb 2009. Jan-Dec 2008 was the baseline. Patients in upfront mobilization clinical trials with plerixafor were excluded. From Feb-Nov 2009, the risk adapted algorithm Plerixafor-1 was used. PBSC mobilization was commenced with G-CSF at 10 mcg/kg/day. If PB CD34 on day 4 or day 5 was ≥ 10/μL, apheresis was commenced the next morning. If PB CD34 was < 10/μL on day 5, plerixafor (0.24 mg/kg sc) was administered in the evening 5 and apheresis was commenced the next day. If daily yield was < 0.5 × 106CD34/kg, plerixafor was added. In Dec 2009, the algorithm was changed to Plerixafor-2. The dosing of G-CSF and plerixafor remained the same, however the thresholds changed to if day 4 PB CD34 < 10 for single or <20/μL for multiple transplants, plerixafor was added. If day 1 yield was <1.5 × 106 CD34/kg, or any subsequent daily yield was < 0.5, plerixafor was added. In the 3 time periods, Jan-Dec 2008, there were 327 mobilization attempts in 286 patients, Feb-Nov 2009, 228 mobilization attempts in 224 pts, and Dec 2009-June 2010, 101 attempts in 100 pts. Costs of the mobilization and collection included drugs costs (cyclophosphamide, G-CSF, GM-CSF and plerixafor), apheresis and cryopreservation. Supportive care costs of transfusions, antibiotics, hospitalizations, nursing costs and patients personal costs were not included. The details of the results are outlined in the table. Plerixafor-2 shows a statistical improvement PBSC collections, increased number of patients reaching minimum and optimal goals, less days of apheresis and total days of mobilization/collection. In conclusion, although the earlier identification of ineffective PBSC mobilization and initiation of plerixafor (Plerixafor-2) increases the costs of PBSC mobilization, more patients are able to achieve the minimum and optimal goals of CD34 collection, failure rates, number of days of apheresis and total days of mobilization/collection are lower. It is unclear if upfront mobilization with plerixafor + G-CSF would result in further benefit.Table 1Results of Mobilization and CollectionBaseline 2008Plerixafor-1Plerixafor-2P valuePatients286224100Mobilization Attempts/Remobilizations327/ 41 (14%)228/ 4 (2%)101/ 1 (1%)CD34 collected - x106/kgMedian5.346.047.72<0.001Range0-25.80.1-28.21.48-29.3Mean5.666.868.16Collections >4 x106/kg (%)223 (68%)185 (81%)93 (92%)<0.001Collections >2x106/kg(%)261 (80%)212 (93%)99 (97%)<0.001Mobilization Failures66 (20%)16 (7%)1 (1%)<0.001Days of ApheresisMedian2320.002Range0-111-121-9Mean2.63.12.5Total Days of Mobilization/CollectionMedian886Range4-284-254-22Mean98.97.2<0.001Total Cost per patientMedian$12 500$12 500$21 000<0.001Minimum$3000$5000$5500Maximum$146 750$93 500$89 750Mean$17 300$21 686$20 695Plerixafor Use29 # (9%)94 (41%)60 (59%)Days- Median532<0.001Range1-101-81-9Mean53.32.6Bone Marrow Harvest∗Cost of bone marrow harvest not inclusded in costs per patient.300#All remobilizations were on the compassionate use protocol. Costs were based on current pricing of plerixafor;∗ Cost of bone marrow harvest not inclusded in costs per patient. Open table in a new tab #All remobilizations were on the compassionate use protocol. Costs were based on current pricing of plerixafor