The vascular niche is involved in regulating leukemic stem cells in murine chronic myelogenous leukemia Djamel Aggoune, John L. Magnani, Richard A. Van Etten, Daniela S. Krause
Disclosures for Investigators In compliance with ACGME policy, ASH requires the following disclosures to the session audience: Research Support/ P.I.! Employee! Research and salary support (Krause),. (Van Etten)! No relevant conflicts of interest to declare! Consultant! Major Stockholder! Speakers Bureau! No relevant conflicts of interest to declare!! No relevant conflicts of interest to declare!! No relevant conflicts of interest to declare! Scientific Advisory Board! No relevant conflicts of interest to declare!! Presentation includes discussion of the following off-label use of a drug or medical device: GMI-1271
Targeting of the osteoblastic niche can eradicate LSC in CML Parathyroid Hormone Bone Resistance to imatinib Disease relapse Disease progression Krause DS et al., 2013, Nat Med; 19(11):1513!
An osteoblastic and a vascular hematopoietic stem cell niche are distinguished! Osteoblastic niche Vascular niche Krause DS, Scadden DT, Preffer FI, 2013, Cytometry Part B; 84(1): 7!
Adhesion pathways employed by normal HSC! and LSC in the BM! Winkler IG, Nat Med. 2012 Nov;18(11):1651! E-selectin promotes HSC proliferation! (Basement membrane) E-selectin inhibitor?!! LSC! CD44 Krause DS et al., Blood 2014; 123(9):1361! (Stromal cell) Jin L et al. Nat. Med. 2006; 12 (10):1167 and! Krause DS et al., Nat. Med. 2006; 12 (10):1175 (Adventitial cell) (Endothelial cell) Mazo IB et al., 1999, J Leuk. Biol.; 66(1):25
E-selectin is exclusively expressed on endothelial cells Hogg N et al., 2011, Nat Rev Immunol; 11: 416
The E-selectin-specific antagonist GMI-1271! Successor of the pan-selectin antagonist Rivipansel (GMI-1070), now in phase 2 clinical trial for vaso-occlusive crisis of sickle cell disease In clinical trial for AML to decrease adhesion of acute ayeloid leukemia blasts to E-selectin Improves survival in mice after high-dose chemotherapy by alleviating mucositis and accelerating neutrophil recovery May be beneficial in inhibiting metastasis and thromboembolic complications
Retroviral BM transduction/transplantation model! Daley GQ, Van Etten RA, Baltimore D, 1990, Science; 247:824! gag pol env BCR/ABL IRES/GFP Donor: 5-FU 200 mg/kg packaging cell 293T CML-like MPD hν prestimulation (IL-3, IL-6, SCF) and ex vivo transduction
The tumor burden is reduced in mice treated with the E-selectin antagonist GMI-1271 +/- imatinib! Day 0 Transplantation Days 10-28 Daily Treatment with vehicle imatinib 100 mg/kg p.o. GMI-1271 20 mg/kg i.p. GMI-1271+imatinib Leukocytes/ul Leukocyte count in peripheral blood GFP + (BCR-ABL1 + ) myeloid cells in peripheral blood 60000 40000 20000 P=0.02 P=0.07 Leukocytes/ ul in peripheral day 16 P=0.02 % GFP+ Mac-1+ cells P=0.03 GFP+ myeloid P=0.04 cells in peripheral blood - tumor burden 15 10 5 P=0.02 0 Vehicle Imatinib GMI GMI+IM 0 Vehicle Imatinib GMI MI+imatinib
Spleen weights are reduced in mice treated! with GMI-1271 plus imatinib! P=0.003 Spleen weights day 17/18 P=0.3 1000 P=0.1 Spleen weight in mg 800 600 400 200 0 vehicle imatinib GMI GMI+IM
GMI-1271 +/- imatinib leads to prolongation! of survival in some mice! Percent overall survival 100 80 60 40 20 P=0.004 Vehicle GMI1271 Imatinib Imatinib + GMI P=0.0003 0 0 20 40 60 80 100 Days after transplantation Survival benefit is not due to increased mobilization of BCR-ABL1 + myeloid cells or LSC to peripheral organs
GMI-1271-treatment significantly reduces BCR-ABL1 + leukemic stem cells!
The tumor burden is reduced in secondary! recipients of GMI1271-treated BM The leukocyte Secondary count transplantation is reduced in of secondary CML BM cells recipients from treated of GMI-treated primary BM donor mice to assess LSC frequency, self-renewal and repopulation efficiency 30000 P=0.04 vehicle Imatinib E-sel.-inh. E-sel.-inh. + IM CML! Leukocytes per ul 20000 10000 0 6 Vehicle IM P=0.058 n.s. GMI GMI+IM untreated % GFP+ Mac-1+ cells 4 2 0 Vehicle IM GMI GMI+IM
Treatment with GMI-1271 and imatinib reduces the cycling of BCR-ABL1 + LKS cells! Frequency of cycling GFP+ LKS 0.4 P=0.03 % of total cells 0.3 0.2 0.1 0.0 Vehicle IM GMI IM+GMI Mac-1
Conclusions! The E-selectin inhibitor GMI-1271 +/- imatinib reduces tumor burden in a murine model of CML. GMI-1271 +/- imatinib prolongs survival in approximately 20% of mice with CML. GMI-1271 reduces LSC in CML and, consequently, tumour burden in secondary recipients. GMI-1271 reduces the cycling of CML stem cells. Modulation of the vascular niche and in particular E-selectin may be a possible strategy to target LSC in CML, in particular when imatinib is discontinued.