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

 

Research Support/ P.I.! Research and salary support (Krause), ……. (Van Etten)!

Employee! No relevant conflicts of interest to declare!

Consultant! No relevant conflicts of interest to declare!!

Major Stockholder! No relevant conflicts of interest to declare!!

Speakers’ Bureau! No relevant conflicts of interest to declare!

Scientific Advisory Board! No relevant conflicts of interest to declare!!

In compliance with ACGME policy, ASH requires the following disclosures to the session audience:

Presentation includes discussion of the following off-label use of a drug or medical device: GMI-1271

Disclosures for Investigators

Targeting of the osteoblastic niche can eradicate LSC in CML  

Bone  

•  Resistance to imatinib •  Disease relapse •  Disease progression

Parathyroid  Hormone  

Krause DS et al., 2013, Nat Med; 19(11):1513!

An osteoblastic and a vascular hematopoietic stem cell niche are distinguished!

Krause DS, Scadden DT, Preffer FI, 2013, Cytometry Part B; 84(1): 7!

Osteoblastic niche Vascular niche

Adhesion pathways employed by normal HSC !and LSC in the BM!

Mazo IB et al., 1999, J Leuk. Biol.; 66(1):25

!LSC !

(Stromal cell)

(Adventitial cell)

(Endothelial cell)

(Basement membrane)

CD44  

Jin L et al. Nat. Med. 2006; 12 (10):1167 and !Krause DS et al., Nat. Med. 2006; 12 (10):1175  

Krause DS et al., Blood 2014; 123(9):1361!

E-selectin inhibitor ?!

Winkler IG, Nat Med. 2012 Nov;18(11):1651! E-selectin promotes HSC proliferation!

Hogg N et al., 2011, Nat Rev Immunol; 11: 416

E-selectin is exclusively expressed on endothelial cells

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

•  May be beneficial in inhibiting metastasis and thromboem- bolic complications

•  Improves survival in mice after high-dose chemotherapy by alleviating mucositis and accelerating neutrophil recovery

Donor: 5-FU 200 mg/kg

gag pol env

293T

prestimulation (IL-3, IL-6, SCF) and ex vivo transduction

packaging cell

hν

IRES/GFP BCR/ABL

Retroviral BM transduction/transplantation model!

Daley GQ, Van Etten RA, Baltimore D, 1990, Science; 247:824 !

CML-like MPD

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

   

Vehicle

Imatinib

GMI

GMI+IM

0

20000

40000

60000

Leukocytes/ul

Leukocytes/ ul in peripheral day 16

P=0.02

P=0.07

P=0.02 Leukocyte count in peripheral blood

Vehicl

e

Imati

nibGMI

GMI+imati

nib0

5

10

15%

GFP

+ M

ac-1

+ ce

lls

GFP+ myeloid cells in peripheral blood - tumor burden

P=0.02

P=0.03

GFP+ (BCR-ABL1+) myeloid cells in peripheral blood

P=0.04

vehicl

e

imati

nibGMI

GMI+IM

0

200

400

600

800

1000

Sple

en w

eigh

t in

mg

Spleen weights day 17/18

P=0.1

P=0.3

P=0.003

Spleen weights are reduced in mice treated !with GMI-1271 plus imatinib !

Survival benefit is not due to increased mobilization of BCR-ABL1+ myeloid cells or LSC to peripheral organs

GMI-1271 +/- imatinib leads to prolongation !of survival in some mice !

0 20 40 60 80 1000

20

40

60

80

100VehicleGMI1271ImatinibImatinib + GMI

Days after transplantation

Per

cent

ove

rall

surv

ival

P=0.004 P=0.0003

GMI-1271-treatment significantly reduces BCR-ABL1+ !

leukemic stem cells!

The leukocyte count is reduced in secondary recipients of GMI-treated BM Secondary transplantation of CML BM cells from treated primary donor mice to assess LSC frequency, self-renewal and repopulation efficiency  

Vehicle

IM GMI

GMI+IM0

10000

20000

30000

Leuk

ocyt

es p

er u

l

P=0.04

untreated

The tumor burden is reduced in secondary !recipients of GMI1271-treated BM  

vehicle Imatinib E-sel.-inh. E-sel.-inh. + IM

CML!

Vehicle

IM GMI

GMI+IM

0

2

4

6%

GFP

+ M

ac-1

+ ce

lls

P=0.058 n.s.

Treatment with GMI-1271 and imatinib reduces the cycling of BCR-ABL1+ LKS cells!

Frequency of cycling GFP+ LKS

Vehicl

e IM GMI

IM+G

MI Mac

-10.0

0.1

0.2

0.3

0.4

% o

f tot

al c

ells

P=0.03

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.