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Stem Cell Mobilization Standards of Care for HSCT Novel Applications. Richard Champlin, M.D. Why is the bone marrow in the bone marrow?. Hematopoietic stem cells home to a “ niche ” in the marrow
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Stem Cell MobilizationStandards of Care for HSCTNovel Applications Richard Champlin, M.D.
Why is the bone marrow in the bone marrow? • Hematopoietic stem cells home to a “niche” in the marrow • Marrow microenvironment provides critical interactions controlling the growth and differentiation of hematopoietic cells • Maturing cells naturally egress the bone marrow into the blood and later into the tissues • Stem cells traffic into and out of the bone marrow physiologically
Stem Cell Niche Bone Marrow Stromal Microenvironment HSC SDF1 CXCR4 VLA-4 VCAM-1 Osteoblasts Pamela S, et al. ASH 2008. Abstract #: 858; Shivtiel et al. J Exp Med. 2008;205:2381.
Mechanisms Governing Stem Cell Mobilization with G-CSF Adhesive interactions between HSC and matrix components in the BM G-CSF Mobilization Cathepsin G (CG), chemokine receptor-4 (CXCR4), hematopoieic stem cell (HSC), hyaluronic acid (HA), interleukin 8 (IL-8), kit ligand (KL), matrix metalloproteinase-9 (MMP-9), neutrophil elastase (NE), stromal cell derived factor-1 (SDF-1), vascular cell adhesion molecule-1 (VCAM-1), very late antigen-4 (VLA-4), P-selectin glycoprotein ligand-1 (PSGL). Source: Nervi B, et al. J Cell Biochem. 2006;99:690-705
Considerations for Mobilization Regimen • Reliable • Collect sufficient number of HSCs and progenitors • Predictable • Able to predict day of collection • Low failure rate • Limited toxicity • Cost Effective • Limited number of days of apheresis required • Low resource utilization • Low tumor contamination
Agents for Stem Cell Mobilization Plerixafor G-CSF Bone Marrow Stromal Microenvironment SDF1 D11-5908 HSC SDF1 CXCR4 PP2 scr inhibitor VLA-4 VCAM-1 Osteoblasts MM9 Fibronectin Scr kinase G-CSF Pamela S, et al. ASH 2008. Abstract #: 858; Shivtiel et al. J Exp Med. 2008;205:2381.
CD34+ Cells Are Heterogenous CD34+ CD34+/CD61+ CD34+/CD38- CD34+/CD61- CD34+/CD133+ CD34+/HLA-DR+ CD34+/HLA-DR- CD34+/CD133- CD34+/CD38- = Most Primitive Stem Cells Hock H. J Exp Med. 2010;207:1127-1130
When to Collect? Correlation between PB CD34+ cells/µL and CD34+ cells/kg collection Armitage S, et al. Bone Marrow Transplant. 1997;20:587-591.
How Many HSCT do you need for AutoSCT? Richard Champlin, MD
Platelet Engraftment Kinetics As A Function Of CD34+ Cell Dose Probability of Engraftment of Platelets ≥ 20 x 109/L 1.0 N = 212 0.9 0.8 0.7 0.6 0.5 0.4 CD34+ Cells x 106/kg 0.3 1.0 2.0 0.2 5.0 10.0 0.1 0.0 7 14 28 28 Days Glaspy JA, et al. Blood. 1997;90(8):2939-2951.
Importance of CD34+Cell Dose Percent Patient Platelet Count > 150,000/L Stiff PJ, et al. Blood. 2008;112:758-759. Abstract 2175.
Defining a Target? • Generally accepted that ≥ 2 x 106 CD34+ cells/kg is ensures a threshold effect for a rapid hematopoietic engraftment1-2 • 95% of patients receiving > 2.5 x 106 CD34+ cells/kg experience durable neutrophil engraftment by day 18 • 5 x 106/kg may be threshold for rapid platelet engraftment3-4 • Unclear if > 5 x 106/kg will result in any better engraftment, may be associated with improved outcome5 1To LB, et al. Blood. 1997;89:2233-58; 2Schiller G, et al. Blood. 1995;86:390-7; 3Kiss JE, et al. Bone Marrow Transplant. 1997;19:303–10; 4Weaver CH, et al. Blood 1995;86:3961–9; 5Dercksen MW, et al. J Clin Oncol. 1995;13:1922–32.
Higher Cell Dose: Impact on Cost • Costs of transplant-related care in patients who experience “good” versus “poor” mobilization • Retrospective analysis of 172 NHL patients treated with HDT and autologous PBSC transplantation • Mobilizations categorized as “poor” (<2 ×106 CD34+ cells/kg) or “good” (≥2 ×106 CD34+ cells/kg) • Cyclophosphamide + G-CSF used for mobilization • Cost data in a subset of patients (n=57) Stockerl-Goldstein KE, et al. Biol Blood Marrow Transplant. 2000;6(5):506-512. a Includes cost of apheresis and bone marrow harvest, if performed.
How to collect HSCT • Chemo-Mobilization • Integrates collection into disease management • Improves CD34 yield • Cost, complications, can’t predict date of collection • We use this for aggressive lymphoma • Growth Factor Mobilization • Simple • Efficient, can schedule • Provides adequate CD34 yield in many categories of patients • Less Costly, few complications, can predict date of collection • May interrupt/delay chemotherapy • We use this for myeloma
Factors Affecting CD34+ Cell Yield Patient-related • Age • Mobilization regimen chosen • Generally higher CD34 yields with chemo-based mobilization • Amount and type of prior therapy • Alkylators, lenalidomide, radiation • Platelet count at the time of mobilization
G-CSF vs Chemotherapy + G-CSF Chemo = various chemotherapeutic agents; Cy = cyclophosphamide; HD = Hodgkin's disease; MM = multiple myeloma; NHL = non-Hodgkin's lymphoma; NR = not reported. 1Alegre A, et al. Bone Marrow Transplant. 1997;20:211–217; 2Desikan KR, et al. J Clin Oncol. 1998;16:1547–1553; 3Dazzi C, et al. Leuk Lymphoma. 2000;39:301–310; 4Narayanasami U, et al. Blood. 2001;98:2059–2064; 5Pusic I, et al. Biol Blood Marrow Transplant 2008;14:1045–1056.
Rituximab and HSC Mobilization- MDACC Experience • Rituximab reduces circulating lymphoma cells • No impact on HSC mobilization, particularly with chemomobilization • Improvement in results of autoSCT using Rituximab in mobilization and transplant.
ASCT for Aggressive NHL Impact of Rituximab on DFS 1.0 p = 0.004 0.9 Rituximab (N=67) 0.8 0.7 0.6 Cumulative Proportion Surviving 0.5 No Rituximab (N=30) 0.4 0.3 0.2 0.1 0.0 0 3 6 9 12 15 18 21 24 27 30 Months Post Transplant
Adhesion Molecules And HSC Mobilization Mobilization Plerixafor Natalizumab BIO5192 Nervi B, et al. J Cell Biochem. 2006;99:690-705.
Plerixafor • A sustained elevation of peripheral blood CD34+ cell levels was noted between 4 and 18 hours1 250 200 150 100 50 n = 3 healthy volunteers 0 0 5 10 15 20 Time (hours) calculated after 4 days of G-CSF therapy and addition of G-CSF + Mozobil™ (plerixafor injection) on day 5 G-CSF, granulocyte-colony stimulating factor. 1. Mozobil™ [prescribing information]. Cambridge, MA: Genzyme Corp; 2008. 2. Adapted from Liles WC, et al. Transfusion. 2005;45:295-300. 20
Mobilization Using G-CSF With Plerixafor • Efficacy as single agent • Synergistic with G-CSF • Increases likelihood of successful CD34+ cell mobilization • QUESTIONS: • Are there important functional differences in the grafts collected? • Are the improvements in CD34 yield worth the added cost? • Effect on mobilization of malignant cells?
Gene Expression of Mobilized CD34+ Cells and Leukocytes Gene expression differs among CD34 cells mobilized plerixafor, G-CSF, and plerixafor + G-CSF Composition of mobilized CD34+ cells is dependent on the mobilization protocol Composition of CD34+ cells mobilized by the combination is not simply a mixture of cells mobilized by each agent separately Donahue RE, et al. Blood. 2009;114:2530-2541.
Functional Differences Noted With Plerixafor vs G-CSF-Mobilized HSPCs Larochelle A, et al. Blood. 2006; 107:3772–3778; Hess DA, et al. Biol Blood Marrow Transplant. 2007; 13:398–411; Fruehauf S, et al. Cytotherapy. 2009; 11:992–1001; Donahue RE, et al. Blood. 2009; 114:2530–2541; Higher proportion of cells in G1 phase of the cell cycle Higher proportion of more ‘primitive’ CD34+CD38- cells More cells expressing CXCR4 and VLA-4 on the cell surface Grafts contain more T, B and NK cells
Plerixafor vs G-CSF-Based Stem Cell Mobilization in HLA-Identical Donors: Allograft Composition *Mean. †Median. ‡Includes 8 donors mobilized by both plerixafor and G-CSF. Devine S, et al. Blood. 2008;112(4):990-998.
Cancer Cell Mobilization in Autologous Donors??? CXCR4 Antagonist CXCR4 / SDF-1 ? Release of Tumor Cells Gazitt Y. Leukemia. 2004;18;1-10.
MDACC Policy PBPC Collection • For autos and allos- goal 5 million, accept minimum 2 million CD34/kg, • Day 1 or 2 stop >4M • Day 3 stop >3M • Day >4 stop >2M • Collect If CD34 > 10/mcl • If collection is ≤ 0.3 million/kg/d x 2 consecutive days despite use of plerixafor or stop apheresis
Myeloma- plan for 2 transplants • Target doses: Goal 6-8 million/kg for 2 transplants (minimum acceptable 4 million/kg) • If after 1 or 2 collections CD34 collected is > 8 million/kg stop • If after 3 collections CD34 collected is > 6 million/kg stop • If after 4 collections CD34 collected > 4 million/kg stop • If after 5 collections CD34 collected > 2 million/kg stop, do one transplant
Just In Time Strategy for Cost Effectiveness • G-CSF alone successfully mobilizes many patients • Plerixafor is synergistic with G-CSF for stem cell mobilization • An approach to improving cost effectiveness is reserving plerixafor for patients with suboptimal mobilization • Use circulating CD34 on day 4 or first day’s collection to determine who needs addition of plerixafor.
Factors Associated With Poor Mobilization • Increasing cycles / duration of prior chemotherapy • Female gender • Prior radiation to bone marrow • Low pre-mobilization platelet count • Bone marrow positivity • Indolent lymphoma histology • Exposure to fludarabine, platinum-based chemotherapy, alkylating agents, lenalidomide • Low PB CD34 count during mobilization
Outcome of Mobilization by Disease 27% 33% 14% Gertz M, et al. Bone Marrow Transplant. 2010 Jan 11. epub.
Percent ≥ 2 Million CD34+ Cells/kgPhase III NHL Study HR=2.50, 95%CI (1.86, 3.36), p<0.0001 Plerixafor +G-CSF Kaplan-Meier estimate of proportion of patients reaching ≥ 2 x 106 CD34+ cells/kg Placebo + G-CSF DiPersio JF, et al. J Clin Oncol. 2009;27:4767-4773.
Conclusions • Hematopoietic stem and progenitor cells are mobilized by G-CSF and plerixafor a CXCR4 inhibitor • Plerixafor mobilizes PBPC by inhibition of SDF-1 and CXCR4 interaction • Plerixafor and G-CSF are synergistic • The combination of Plerixafor and G-CSF will reduce the number of aphereses required for PBPC collection and enhance to ability to perform autologous HSCT in “hard to mobilize” patients • Chemotherapy plus growth factor enhances mobilization and is warranted when the chemotherapy is indicated for treatment of the malignancy