1. Brief Overview of Hematopoietic Cell Transplantation (HCT) Use

2. History of Early Peripheral Blood Stem Cell Transplant (PBSCT) Use
Hematopoietic stem cells (HSC) identified in peripheral blood1
Peripheral blood stem cells (PBSCs) facilitate recovery of hematopoietic system after myeloablation2
PBSC transplantation used for patients unable to undergo bone marrow transplantation (BMT)3
Collection of PBSCs using mobilization more efficient than not using mobilization4
Validation of CD34+ cells as a surrogate for hematopoietic potential5
1962
1980s
1990s
and later
In 1962, hematopoietic stem cells (HSCs) were identified in peripheral blood.1
The usefulness of PBSCs became better appreciated in the 1980s when landmark publications reported that peripheral blood stem cell transplant (PBSCT) could recover the hematopoietic system after myeloablation with cytotoxic therapy.2
Initially, however, PBSCT was only used for patients who were not considered for bone marrow transplantation (BMT).3
For example, Kessinger et al. showed that autologous PBSCT was feasible in 40 patients with refractory lymphoma who were ineligible for BMT because of metastases, prior pelvic radiation therapy, hypocellular BM, or history of BM involvement.3
And finally, in the 1990s, the efficiency of collecting PBSCs with mobilization was shown, and CD34+ was validated as a surrogate for hematopoietic potential.4,5
References
Goodman JW, Hodgson GS. Evidence for stem cells in peripheral blood of mice. Blood ;19:
Motabi IH, Dipersio JF. Advances in stem cell mobilization. Blood Rev. 2012;26(6):
Kessinger A, Armitage JO, Smith DM, Landmark JD, Bierman PJ, Weisenburger DD. High-dose therapy and autologous peripheral blood stem cell transplantation for patients with lymphoma. Blood. 1989;74(4):
Damon LE, Damon LE. Mobilization of hematopoietic stem cells into the peripheral blood. Expert Rev Hematol. 2009;2(6):
Weaver CH, Hazelton B, Birch R, et al. An analysis of engraftment kinetics as a function of the CD34 content of peripheral blood progenitor cell collections in 692 patients after the administration of myeloablative chemotherapy. Blood. 1995;86:
Goodman JW, et al. Blood. 1962;19:
Motabi IH, et al. Blood Rev. 2012;26(6):
Kessinger A, et al. Blood. 1989;74(4):
Damon LE, et al. Expert Rev Hematol. 2009;2(6):
Weaver CH, et al. Blood. 1995;86:

3. Distinct Goals of Autologous HCT Therapy
Goals of therapy
Regenerate hematopoietic cell system after myeloablative therapy
Sustained engraftment of the infused cells
Irrespective of whether peripheral blood or BM is used, the overarching goal of HCT is 2-fold:
To help regenerate the hematopoietic system after myeloablative therapy
To achieve engraftment of the infused cells and to maintain the engraftment long-term
Reference
Benn H, Rowley SD. Bone marrow and peripheral blood stem cell transplantation. In: Hillyer CD, Sillberstein LE, Ness PM, Anderson KC, Roback JD, eds. Blood Banking and Transfusion Medicine: Basic Principles and Practice. 2nd ed. Philadelphia, PA: Churchill Livingstone; 2006:
Benn H, et al. In: Hillyer CD, et al., eds. Blood Banking and Transfusion Medicine: Basic Principles and Practice. 2nd ed.
Philadelphia, PA: Churchill Livingstone; 2006.

4. Advantages of Peripheral Blood vs Bone Marrow as Stem Cell Source
Collection in outpatient setting1
Avoidance of general anesthesia1
Accelerated engraftment1
Shorter duration of hospitalization2
Improved effectiveness1
Stem Cell Migration3
Physiologic circulation of stem cells
Stomach
Given these advantages, peripheral blood has mostly replaced bone marrow as the source for autologous HCT4
Returns to the
bone marrow
from the blood
In addition to peripheral blood collection being an outpatient procedure that does not require general anesthesia, it has been associated with shorter hospital stays and improved outcomes, including survival.1,2
Given these advantages, peripheral blood is preferred over BM, particularly for autologous SCT.3
References
Vose JM, Sharp G, Chan WC, et al. Autologous transplantation for aggressive non-Hodgkin's lymphoma: results of a randomized trial evaluating graft source and minimal residual disease. J Clin Oncol. 2002;20(9):
Schmitz N, Linch DC, Dreger P, et al. Randomised trial of filgrastim-mobilised peripheral blood progenitor cell transplantation versus autologous bone-marrow transplantation in lymphoma patients. Lancet. 1996;347:
Benn H, Rowley SD. Bone marrow and peripheral blood stem cell transplantation. In: Hillyer CD, Sillberstein LE, Ness PM, Anderson KC, Roback JD, eds. Blood Banking and Transfusion Medicine: Basic Principles and Practice. 2nd ed. Philadelphia, PA: Churchill Livingstone; 2006:
Migrates out of
the bone to the
peripheral organs
Liver
Liver
Vose JM, et al. J Clin Oncol. 2002;20(9):
Schmitz N, et al. Lancet. 1996; 347:
Laird DJ, et al. Cell. 2008;132:
Benn H, et al. In: Hillyer CD, et al., eds. Blood Banking and Transfusion Medicine: Basic Principles and Practice. 2nd ed. Philadelphia, PA: Churchill Livingstone; 2006.
Heart

5. Mobilization Strategies
Cytokines and Chemomobilization
Given the limitations of collecting PBSCs, mobilizing agents emerged to overcome these challenges.

6. Early Use of Chemotherapy to Mobilize Stem Cells
Prior to cytokines becoming widely available, only chemotherapy was in use to mobilize stem cells1
Chemotherapy choice depends on patient treatment needs2
Although several regimens have been used for mobilization,2 cyclophosphamide is the most commonly used agent3
Prior to cytokines becoming widely available, only chemotherapy was in use to mobilize stem cells1
Chemotherapy represents a strategy for mobilization; it induces myelosuppression, after which, hematopoiesis rebounds.2
As it does, maturing granulocytes secrete proteases, which may eliminate the anchor affixing HSCs to the BM, resulting in mobilization.2
Cyclophosphamide is the most frequently used chemotherapy agent for mobilization.2
The median number of CD34+ cells collected on the first apheresis day after cyclophosphamide mobilization is approximately 0.9 × 106/kg.3
Cyclophosphamide is not approved specifically for HSC mobilization; rather, it is indicated to treat multiple myeloma (MM) and other hematologic malignant conditions and solid tumors.4
References
Motabi IH, Dipersio JF. Advances in stem cell mobilization. Blood Rev. 2012;26(6):
Rowley SD, Donato ML. Practical aspects of stem cell harvesting and mobilization. In: Hoffman R, Benz EJ, Silberstein LE, Heslop HE, Weitz JI, eds. Hematology: Basic Principles and Practice. 6th ed. Philadelphia, PA: Elsevier Saunders; 2013:
Damon LE, Damon LE. Mobilization of hematopoietic stem cells into the peripheral blood. Expert Rev Hematol. 2009;2(6):
Cytoxan (cyclophosphamide) [package insert] Princeton, NJ: Bristol-Myers Squibb; 2005.
Motabi IH, et al. Blood Rev. 2012;26(6):
Rowley SD, et al. In: Hoffman R, et al., eds. Hematology: Basic Principles and Practice. 6th ed. Philadelphia, PA Elsevier Saunders; 2013:
Damon LE, et al. Expert Rev Hematol. 2012;2(6):

7. Mechanism of Action of Cytokine-Mediated Mobilization
Cytokine Mechanisms2
Leukocytes
Stromal cells
Degradation of the ECM
CXCR-4
SDF-1
HSC
HPC
G-CSF
MMP
elastases
cathepsin G
Loss of attachment to stromal cells
and the ECM EC
Cytokines induce granulocytes, trigger the proliferation and elaboration of proteases that mediate mobilization, stimulate osteoclast activity, and down-regulate SDF 11
When used in the absence of chemotherapy, cytokines induce granulocytes, triggering the elaboration of proteases and subsequent mobilization of HSCs. 1
Cytokines also induce osteoclast activity, thus triggering hematopoiesis, and they down-regulate chemokine (C-X-C motif) ligand 12 (CXCL12) (SDF-1α), leading to a decrease in binding to and sequestering by CXCR-4.1
Reference
Damon LE, Damon LE. Mobilization of hematopoietic stem cells into the peripheral blood. Expert Rev Hematol. 2009;2(6):
Damon LE, et al. Expert Rev Hematol. 2009;2(6):
Lataillade JJ, et al. Eur Cytokine Netw. 2004;15(3):

8. Mobilization of HSCs With Combined Chemotherapy and Cytokine Therapy
Study
Patient Population
Mobilization Regimen
CSF = Colony Stimulating Factor
CD34+ Cells Collected, cells/kg
Chemotherapy + Cytokines
Cytokines Alone
Koc et al1,a
N=29; 12 with lymphoma, 8 with MM, 9 with solid tumors
Cyclophosphamide (CY) 4 g/m2 on day 1 + CSF (36-48 h later) vs CSF (days 1-12)
3.36 × 106
(P=0.0075)
1.36 × 106
Karanth et al2,b
N=79; 22 with CLL, 35 with MM, 16 with NHL, and 6 with HL
CY 2 g/m2 on day 1 + CSF (day 5 until collection) vs
CSF (days 1-5 or until collection completed)
2.2 × 106
2.3 × 106
Gertz et al3
N=716 patients with MM
CY 1.5 g/m2 on days 1 and 2 + CSF (day 3 through collection) vs CSF (days 1 through collection; dose increases permitted)
10.3 × 106
(P=0.01)
9.9 × 106
Sung et al4,b
N=226 patients
162 MM (M)
64 Lymphoma (L)
Various chemotherapies – Majority CY 3 g/m2 (97% L and 83% M) + CSF (3 days after chemotherapy for L and 4 days for M) vs. CSF (median of 10 days with CY arms and 6 days with CSF alone arms)
M 13.8 × 106 (P<0.001)
L 6.6 × 106
M 6.8 × 106 (P<0.001)
L 5.5 × 106
The studies listed in the table are additional examples for the mobilization effectiveness of chemotherapy plus cytokines compared with cytokines alone.1-4
References
Koc ON, Gerson SL, Cooper BW, et al. Randomized cross-over trial of progenitor-cell mobilization: High dose cyclophosphamide plus granulocyte colony-stimulating factor (G-CSF) versus granulocyte-macrophage colony-stimulating factor plus G-CSF. J Clin Oncol. 2000;18:
Karanth M, Chakrabarti S, Lovell RA, et al. A randomised study comparing peripheral blood progenitor mobilisation using intermediate-dose cyclophosphamide plus lenograstim with lenograstim alone. Bone Marrow Transplant. 2004;34:
Gertz MA, Kumar SK, Lacy MQ, et al. Comparison of high-dose CY and growth factor with growth factor alone for mobilization of stem cells for transplantation in patients with multiple myeloma. Bone Marrow Transplant. 2009; 43:
Sung AD, Grima DT, Bernard LM, et al. Outcomes and costs of autologous stem cell mobilization with chemotherapy plus G-CSF vs G-CSF alone. Bone Marrow Transplant. 48:
Results without P value
Not significant
aMean CD34+ counts shown; bMedian CD34+ counts shown.
CLL, chronic lymphocytic leukemia; HL, Hodgkin lymphoma; NHL, non-Hodgkin lymphoma.
Koc ON, et al. J Clin Oncol. 2000;18:
Karanth M, et al. Bone Marrow Transplant. 2004;34:
Gertz MA, et al. Bone Marrow Transplant. 2009;43:
Sung AD, et al. Bone Marrow Transplant. 2013;48:

9. When Used for Mobilization, Cyclophosphamide Did Not Alter Multiple Myeloma Disease Control
To determine whether high-dose cyclophosphamide increases cytoreduction, Dingli et al retrospectively evaluated outcomes in patients with MM who received cytokines with or without cyclophosphamide 3 g/m2 for mobilization.
Median disease duration was approximately 200 days in participants who did not have circulating myeloma cells at the time of autologous SCT. Most of these participants received dexamethasone with or without thalidomide or vincristine/doxorubicin.
Although cyclophosphamide accelerated HSC collection, compared with cytokines alone (2 vs 4 apheresis sessions; P<0.0001), no significant differences in complete response rates or time to progression (19.9 vs 20.9 months, respectively [P=0.59]) was reported.
Reference
Dingli D, Nowakowski GS, Dispenzieri A, et al. Cyclophosphamide mobilization does not improve outcome in patients receiving stem cell transplantation for multiple myeloma. Clin Lymphoma Myeloma ;6(5):
*Progression: Positive immunofixation in patients who previously had a complete response after autologous SCT or 50% increase in serum or urine monoclonal protein in patients who previously had a partial response.
Dingli D, et al. Clin Lymphoma Myeloma. 2006;6(5):

10. When Used for Mobilization, Cyclophosphamide Did Not Alter MM Disease Control
Event-free Survival
Bacon et al
Retrospective analysis (N=186) of patients with MM showed that, compared with cytokines alone, cytokines + high-dose cyclophosphamide was associated with
No significant differences in posttransplant efficacy outcomes
Significantly increased toxicity
Overall Survival
Bacon et al presented a poster at the 2011 annual meeting of the American Society of Hematology, comparing outcomes of patients with newly diagnosed MM treated with G-CSF alone or G-CSF plus cyclophosphamide 4 g/m2.
Compared with patients who received cytokines alone, those given cyclophosphamide plus cytokines had nonsignificantly different
Very good partial response rates or better (60% vs 49%; P=0.33)
Event-free survival (22.6 vs 21.6 months; P=0.62)
Median overall survival (62.3 vs 68.2 months; P=0.23)
Significantly increased rates of adverse events were reported with cyclophosphamide plus cytokines, compared with cytokines alone, including hospitalization, gastrointestinal toxicity, hemorrhagic cystitis, and febrile neutropenia.
Based on these findings, Bacon et al. concluded that using high-dose cyclophosphamide as a mobilization strategy does not improve posttransplant responses.
Reference
Bacon WA, Long GD, Rizzieri DA, et al. Impact of high dose cyclophosphamide on the outcome of autologous stem cell transplant in patients with newly diagnosed multiple myeloma [ASH abstract 4127]. Blood. 2011;118.
Bacon WA, et al. [ASH abstract 4127]. Blood. 2011;118.

11. Cytokines Alone Elicit Engraftment Kinetics Similar to That of Cytokines + Cyclophosphamide
Outcome with cytokines alone compared with that achieved with cytokines + cyclophosphamide (CTX)
Event-free Survival
The engraftment kinetics of cytokines alone also was similar to that of cytokines plus cyclophosphamide.1
Shown here are data from a study by Desikan et al, who demonstrated nonsignificantly different engraftment kinetics with cytokines vs cytokines plus cyclophosphamide.1
In this study, the time to engraftment was similar between the 2 treatment arms despite a greater number of CD34+ cells/kg infused in patients receiving cytokines with cyclophosphamide (compared with cytokines alone).1
Recall from the study by Bacon et al that, compared with patients who received cytokines alone, those given cyclophosphamide plus cytokines had nonsignificantly different2
Very good partial response rates or better (60% vs 49%; P=0.33)
Event-free survival (22.6 vs 21.6 months; P=0.62)
Median overall survival (62.3 vs 68.2 months; P=0.23)
Are the comparable engraftment kinetics shown here consistent with your experience in patients who receive cytokines, vs those who receive cytokines plus chemotherapy?
References
Desikan KR, Barlogie B, Jagannath S, et al. Comparable engraftment kinetics following peripheral-blood stem-cell infusion mobilized with granulocyte colony-stimulating factor with or without cyclophosphamide in multiple myeloma. J Clin Oncol. 1998;16(4):
Bacon WA, Long GD, Rizzieri DA, et al. Impact of high dose cyclophosphamide on the outcome of autologous stem cell transplant in patients with newly diagnosed multiple myeloma [ASH abstract 4127]. Blood. 2011;118.
Desikan KR, et al. J Clin Oncol. 1998;16(4):

12. Limitations of Using Cytokines Alone
Limitations: Inadequate PBSC collection in some patients
Lacativa et al1 (MM)
Patient Characteristics Evaluated
PBSC Failure (<4 × 106 cells/kg) (n=62)
PBSC Success (≥4 × 106 cells/kg) (n=92) P
Age, median years (range)
60 (29-70)
54 (33-67)
<0.001
PBSC count before collection, median cells/kg (range)
11.5 (0-43)
27 ( )
Number of sessions, n (%)* 1 2 3
6 (11)
10 (18)
37 (66)
3 (5)
46 (50)
37 (40)
9 (10)
One limitation of using cytokines alone for mobilization is collection failure in certain populations.
The top table shows data from a 2012 retrospective review of 186 patients with MM who received cytokine therapy alone for mobilization.1
As indicated, a greater percentage of older individuals, patients with lower numbers of PBSC before collection, and those requiring a higher number of sessions experienced PBSC failure, as defined by the collection of less than 4 × 106 CD34+ cells/kg.1
Micallef et al. also retrospectively investigated factors associated with collection failure (bottom table).2
The study included 52 patients with NHL who received cytokine therapy alone for mobilization.2
The investigators found that BM infiltration was significantly associated with collection failure.2
References
Lacativa CP, Lacativa PG, Garnica M, et al. Risk factors for unsuccessful peripheral blood stem cell harvesting using granulocyte-colony stimulating factor mobilization in patients with multiple myeloma. Transfus Apher Sci. 2012;47(3):
Micallef IN, Apostolidis J, Rohatiner AZ, et al. Factors which predict unsuccessful mobilisation of peripheral blood progenitor cells following G-CSF alone in patients with non-Hodgkin's lymphoma. Hematol J. 2000;1(6):
Micallef et al2 (NHL)
Bone Marrow Infiltration
(n=19)
(n=33) P
Any time 16 20
0.02
At diagnosis 13
0.002
At mobilization 3 6
0.83
*Data not available in 6 patients in the failure group.
Lacativa CP, et al. Transfus Apher Sci. 2012; 47(3):
Micallef IN, et al. Hematol J. 2000;1(6):

13. Limitations in Cytokine Mobilization in Patients Treated With Certain Agents
Certain treatments linked to collection failure
Radiation therapy1
Radioimmunoconjugate2
Melphalan3
Fludarabine4
Lenalidomide5
Effect of Lenalidomide on Mobilization5
Dex VAD Thal Dex Len Dex
12.00
P<0.001
10.00
8.00
CD34/kg, million
6.00
Cytokines typically mobilize fewer CD34+ cells in patients who previously received radiation therapy, radioimmunoconjugate, or cytotoxic agent than in untreated patients.1,2
In a study by Moskowitz et al, patients treated with melphalan or other stem cell‒toxic therapies (eg, nitrosureas and nitrogen mustards) had 3-fold lower mobilization than patients who did not receive these agents (P=0.005).3
This study also reported that, in general, heavily pretreated patients (ie, ≥11 cycles of chemotherapy) had mobilized half as many CD34+ cells as patients who received fewer than 11 cycles previously (P=0.02).3
The Micallef et al study showed that more than half the patients who received fludarabine and subsequently underwent mobilization experienced unsuccessful PBSC collection.4
Finally, lenalidomide also has been linked to inefficient mobilization with cytokines.5
As shown in the graph, receiving lenalidomide (with dexamethasone) for induction was associated with a significantly lower overall CD34+ collection than receiving other induction regimens.5
References
Rowley SD, Donato ML. Practical aspects of stem cell collection. In: Hoffman R, Benz EJ, Shattil SJ, et al, eds. Hematology: Basic Principles and Practice. 6th ed. Philadelphia, PA Elsevier Saunders; 2013:
Richman CM, Schuermann TC, Wun T, et al. Peripheral blood stem cell mobilization for hematopoietic support of radioimmunotherapy in patients with breast carcinoma. Cancer. 1997;80(12 suppl):
Moskowitz CH, Glassman JR, Wuest D, et al. Factors affecting mobilization of peripheral blood progenitor cells in patients with lymphoma. Clin Cancer Res. 1998;4(2):
Micallef IN, Apostolidis J, Rohatiner AZ, et al. Factors which predict unsuccessful mobilisation of peripheral blood progenitor cells following G-CSF alone in patients with non-Hodgkin's lymphoma. Hematol J. 2000;1(6):
Kumar S, Dispenzieri A, Lacy MQ, et al. Impact of lenalidomide therapy on stem cell mobilization and engraftment post-peripheral blood stem cell transplantation in patients with newly diagnosed myeloma. Leukemia. 2007;21(9):
4.00
2.00
Dex, dexamethasone; VAD, vincristine-adriamycin-dexamethasone; Thal Dex, thalidomide-dexamethasone; Len Dex, lenalidomide-dexamethasone.
0.00
Rowley SD, et al. In: Hoffman R, et al., eds. Hematology: Basic Principles and Practice. 6th ed. Philadelphia, PA Elsevier Saunders; 2013:
Richman CM, et al. Cancer. 1997;80(12 suppl):
Moskowitz CH, et al. Clin Cancer Res. 1998;4(2):
Micallef IN, et al. Hematol J. 2000;1(6):
Kumar S, et al. Leukemia. 2007;21(9):
Total Collection

14. Summary
PBSCT has mostly replaced BMT for patients undergoing autologous HCT
Mobilization strategies emerged to overcome early limitations of collecting PBSCs
Using chemotherapy + cytokines for mobilization is effective but is not associated with improved outcomes versus cytokines alone
In summary:
PBSCT has mostly replaced BMT for patients undergoing autologous HCT
Mobilization strategies emerged to overcome early limitations of collecting PBSCs
Using chemotherapy + cytokines for mobilization is effective but is not associated with improved outcomes versus cytokines alone