***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    ***EXAMPLES*** 
    Input: The introduction of plerixafor has enabled successful collection of stem cells in the majority of patients with lymphoma or myeloma in whom previous attempts at mobilization have failed . However , a proportion of patients have been shown to be resistant to this mobilization regimen . To identify the factors that impair stem cell mobilization and collection with plerixafor , we review ed the data for 197 patients who had undergone mobilization with plerixafor and granulocyte‐colony stimulating factor in Central Europe . Predictors of mobilization failure were evaluated using logistic regression analysis . Among the 197 patients mobilized , the target of ≥2.0 × 106 CD34 + cells/kg was collected from 133 ( 67.5 % ) . Our analysis revealed that previous treatment with lenalidomide , bortezomib , melphalan , radiotherapy , or autologous stem cell transplantation and regimen of plerixafor use in combination with chemotherapy had no significant effect on the efficiency of collection . In contrast , an age ≥65 years ( odds ratio 0.331 , 95 % CI : 0.112–0.977 , P < 0.05 ) , a diagnosis of non‐Hodgkin 's lymphoma ( odds ratio 0.277 , 95 % CI : 0.124–0.622 , P < 0.01 ) , and treatment with ≥ four chemotherapy regimens ( odds ratio 0.366 , 95 % CI : 0.167–0.799 , P < 0.05 ) were associated significantly with failed mobilization . The rate of successful mobilizations was decreased in patients treated with purine analogues ( odds ratio 0.323 , 95 % CI : 0.096–1.094 , P = 0.07 ) but increased in female patients ( odds ratio 1.961 , CI : 0.943–4.080 , P = 0.07 ) . Patients who are characterized by the above negative features could benefit potentially from further improvement in the mobilization strategy . Am . J. Hematol . , 2011 . © 2011 Wiley‐Liss , This phase 3 , multicenter , r and omized ( 1:1 ) , double-blind , placebo-controlled study evaluated the safety and efficacy of plerixafor with granulocyte colony-stimulating factor ( G-CSF ) in mobilizing hematopoietic stem cells in patients with multiple myeloma . Patients received G-CSF ( 10 microg/kg ) subcutaneously daily for up to 8 days . Beginning on day 4 and continuing daily for up to 4 days , patients received either plerixafor ( 240 microg/kg ) or placebo subcutaneously . Starting on day 5 , patients began daily apheresis for up to 4 days or until more than or equal to 6 x 10(6 ) CD34(+ ) cells/kg were collected . The primary endpoint was the percentage of patients who collected more than or equal to 6 x 10(6 ) CD34(+ ) cells/kg in less than or equal to 2 aphereses . A total of 106 of 148 ( 71.6 % ) patients in the plerixafor group and 53 of 154 ( 34.4 % ) patients in the placebo group met the primary endpoint ( P < .001 ) . A total of 54 % of plerixafor-treated patients reached target after one apheresis , whereas 56 % of the placebo-treated patients required 4 aphereses to reach target . The most common adverse events related to plerixafor were gastrointestinal disorders and injection site reactions .  Plerixafor and G-CSF were well tolerated , and significantly more patients collected the optimal CD34(+ ) cell/kg target for transplantation earlier compared with G-CSF alone . This study is registered at www . clinical trials.gov as # NCT00103662 Fludarabine and lenalidomide are essential drugs in the front-line treatment of non-Hodgkin lymphoma ( NHL ) and multiple myeloma ( MM ) , respectively . Data suggests that fludarabine and lenalidomide therapy may have a deleterious effect on stem cell mobilization . In the European compassionate use program , 48 patients ( median age 57 years ) previously treated with fludarabine ( median 5 cycles ; range : 1 - 7 cycles ) were given plerixafor plus granulocyte colony-stimulating factor ( G-CSF ) for remobilization following a primary mobilization attempt . The overall median number of CD34 + cells collected was 2.3 × 10(6)/kg ( range : 0.3 - 13.4 ) . The minimum required number of CD34 + cells ( ≥2.0 × 10(6)/kg ) was collected from 58 % of patients in a median of 2 days . Thirty-five patients ( median age = 57 years ) previously treated with lenalidomide  ( median 5 cycles ; range : 1 - 10 cycles ) were given plerixafor plus G-CSF for remobilization . The overall median number of CD34 + cells collected was 3.4 × 10(6)/kg ( range : 1.1 - 14.8 ) . The minimum required number of CD34 + cells ( ≥2.0 × 10(6 ) per kg ) was collected from 69 % of patients in a median of 2 days . In conclusion , salvage mobilization  with plerixafor plus G-CSF is successful in the majority of patients with MM previously treated with lenalidomide . In fludarabine-exposed patients , only 58 % of patients will achieve successful salvage mobilization  with plerixafor plus G-CSF , suggesting the need for novel mobilization regimens algorithms in this subgroup of patients In a phase 3 multicenter , r and omized , double-blinded , placebo-controlled study of 298 patients with non-Hodgkin lymphoma ( NHL ) , granulocyte colony-stimulating factor ( G-CSF ) plus plerixafor increased the proportion of patients who mobilized > or=5 x 10(6 ) CD34(+ ) hematopoietic stem cells (HSCs)/kg compared with placebo plus G-CSF ( P < .001 ) . Patients in either study arm who failed mobilization ( < 0.8 x 10(6 ) CD34(+ ) cells/kg in 2 collection s or < 2 x 10(6 ) CD34(+ ) cells/kg in 4 collection s ) were eligible to enter the opened-label rescue protocol . Following a 7-day minimum rest period , these patients received G-CSF ( 10 microg/kg/day ) for 4 days , followed by daily plerixafor ( 0.24 mg/kg ) plus G-CSF and apheresis for up to 4 days . Of the 68 patients failing initial mobilization  ( plerixafor , n = 11 ; placebo , n = 57 ) , 62 patients ( 91 % ) entered the rescue procedure ( plerixafor , n = 10 ; placebo , n = 52 ) . Four of 10 patients ( 40 % ) from the plerixafor group and 33 of 52 ( 63 % ) from the placebo group mobilized sufficient CD34(+ ) cells ( > or= 2 x 10(6 ) cells/kg ) for transplantation from the rescue mobilization alone ( P = .11 ) . Engraftment of neutrophils ( 11 days ) and platelets ( 20 days ) was similar to that in patients who did not fail initial mobilization , and all patients had durable grafts at the 12-month follow-up . Common plerixafor-related adverse events ( AEs ) included mild gastrointestinal ( GI ) effects and injection site reactions . There were no drug-related serious AEs . These data support that plerixafor plus G-CSF can safely and effectively remobilize patients with NHL who have failed previous mobilization Hematopoietic progenitor cells ( HPCs ) traffic to and are retained in the marrow through the trophic effects of the chemokine stromal cell-derived factor-1alpha ( SDF-1alpha ) binding to its receptor , CXC chemokine receptor 4 ( CXCR4 ) . AMD3100 reversibly inhibits SDF-1alpha/CXCR4 binding , and AMD3100 administration mobilizes CD34(+ ) cells into the circulation . We therefore tested the hypotheses that the combination of AMD3100 plus granulocyte colony-stimulating factor ( G-CSF ) ( hereafter A + G ) would be superior to G-CSF alone ( hereafter G ) in mobilizing hematopoietic progenitor cells ( HPCs ) and that A + G-mobilized cells would engraft as well as G-mobilized cells . The primary objective was to determine whether patients mobilized more progenitor cells per unit of blood volume of apheresis after A + G administration versus G alone . Secondary objectives were to determine whether patients mobilized with A + G compared with G alone required fewer apheresis procedures to reach the target level at least 5 x 10(6 ) CD34(+ ) cells/kg for transplantation and to determine whether patients mobilized with A + G had at least a 90 % success rate of autologous transplantation as assessed by neutrophil engraftment by day 21 . Each patient served as his or her own control in a sequential mobilization design . All study objectives were met without significant toxicity . The results demonstrate that the combination of A + G is generally safe , effective , and superior to G alone for autologous HPC mobilization The CXCR4-inhibitor plerixafor mobilizes hematopoietic stem cells amplifying the effects of granulocyte-CSF ( G-CSF ) . Before approval plerixafor was used in a compassionate use program ( CUP ) for patients who failed a previous mobilization . In the German CUP 60 patients from 23 centers ( median age 56.5 years ( 2–75 ) ) were given 240 μg/kg plerixafor SC 9–11 h before apheresis . A total of 78.3 % ( 47/60 ) received G-CSF for 4 days before plerixafor administration ; 76.6 % of those ( 36/47 ) yielded at least 2.0 × 106 CD34 + cells/μL. The median cell yield was 3.35 × 106 CD34 + cells/kg ( 0–29.53 ) . Nine patients received plerixafor alone or with G-CSF for less than 4 days mobilizing a median of 3.30 × 106 CD34 + cells/kg ( 1.6–5.6 ) . There was no significant difference between G-CSF application for 4 days and for a shorter period of time ( P=0.157 ) . A total of 47 patients  received plerixafor plus G-CSF combined with chemotherapy yielding a median of 3.28 × 106 CD34 + cells/kg ( 0–24.79 ) . In all , 40 of 60 patients ( 66.7 % ) proceeded to transplantation , and achieved a timely and stable engraftment . Side effects were rare and manageable . In conclusion , mobilization with plerixafor in poor mobilizers is safe and results in a sufficient stem cell harvest in the majority of patients Many institutions have adopted algorithms based on preapheresis circulating CD34 + cell counts to optimize the use of plerixafor . However , a circulating peripheral blood CD34 + cell threshold that predicts mobilization failure has not been defined . The superiority of plerixafor + granulocyte colony-stimulating factor ( G-CSF ) over placebo + G-CSF for hematopoietic stem cell mobilization and collection was shown for patients with non-Hodgkin lymphoma in a phase III , prospect i ve , r and omized , controlled study . The question remains as to which patients may benefit most from the use of plerixafor . In this post hoc retrospective analysis , mobilization outcomes were compared between the 2 treatment arms in patients stratified by peripheral blood CD34 + cell count ( < 5 , 5 to 9 , 10 to 14 , 15 to 19 , or ≥20 cells/μL ) obtained before study treatment and apheresis . Compared with placebo plus G-CSF , plerixafor plus G-CSF significantly increased the peripheral blood CD34 + cells/μL over prior day levels in all 5 stratified groups . The probability of subsequent transplantation without a rescue mobilization was far greater in the plerixafor-treated patients for the lowest initial ( day 4 ) peripheral blood CD34 + cells/μL groups ( < 5 , 5 to 9 , or 10 to 14 ) . Engraftment and durability were the same for the 2 treatment groups for all strata , but the effect in the lower strata could be altered by the addition of cells from rescue mobilizations . These findings may provide insight into the optimal use of plerixafor in all patients undergoing stem cell mobilization PURPOSE This study evaluates the safety and efficacy of plerixafor ( AMD3100 ) , a CXCR4 antagonist , in mobilizing hematopoietic stem cells for autologous stem-cell transplantation in non-Hodgkin 's lymphoma ( NHL ) patients . PATIENTS AND METHODS This is a phase III , multicenter , r and omized ( 1:1 ) , double-blind , placebo-controlled study . Patients with non-Hodgkin 's lymphoma requiring an autologous hematopoietic stem-cell transplantation in first or second complete or partial remission were eligible . Patients received granulocyte colony-stimulating factor ( G-CSF ; 10 microg/kg ) subcutaneously daily for up to 8 days . Beginning on evening of day 4 and continuing daily for up to 4 days , patients received either plerixa 
    Output:
    
AUTHORS ' CONCLUSIONS The results of the analysed data suggest that additional plerixafor leads to increased stem cell collection in a shorter time .
There was insufficient evidence to determine whether additional plerixafor affects survival or adverse events .