Hydroxycarbamide: Mode of action. Jacques Elion, MD, PhD

Size: px

Start display at page:

Download "Hydroxycarbamide: Mode of action. Jacques Elion, MD, PhD"

Dinah Bates
9 years ago
Views:

Hydroxycarbamide: Mode of action Jacques Elion, MD, PhD jacques.elion@inserm.

1 Hydroxycarbamide: Mode of action Jacques Elion, MD, PhD National Reference Centers for Sickle Cell Disease Department of Medical Genetics and UMR 665 Robert Debré University Hospital, 7519 Paris, France Guadeloupe University Hospital, Les Abymes (French West Indies) 3èmes Journées de la Drépanocytose en Martinique Trois Ilets février 213

2 HYDROXYCARBAMIDE (HC) Hydroxyurea is the only effective drug in SCD FDA 1998 (adults) EMEA 27 (adults and children) DROXIA Bristol-Myers Squibb SIKLOS AddMedica Initial expectation from HC: increased HbF expression deoxyhbs polymer decreased HbS polymerisation reduced vaso-occlusion Heterotetramer a2b S g HbF a2g2 Glu g Glu g

3 HYDROXYCARBAMIDE & Sickle Cell Disease but Oral HC : proven efficacy in clinical trials (adults & children) (Charache S et al, N Engl J Med 1995) Early clinical response Delayed and variable Hb F increase Ware RE, et al. Blood. 22;99:1-4

Induction of HbF by HC French pediatric trial Discordance 4 HbF (%) between clinical effect and 35 expected biological effect 3 25 2 What are the targets of HC?

4 Induction of HbF by HC French pediatric trial Discordance 4 HbF (%) between clinical effect and 35 expected biological effect What are the targets of HC? What are the molecular mechanisms of HC action? treatment period (M) De Montalembert M, et al, J Pediatr Hematol, 1997, 19: Maier-Redelsperger M, et al. Blood, 1998, 91: UMR_S 665

5 In Sickle Cell Disease abnormal cell adhesion to the endothelium plays a major in targetting vaso-occlusion Mohandas & Evans, Blood 1984.but so does the vascular tone

6 Could HC affect cell adhesion? from JP Cartron SCADHESION project C Le Van Kim, PL Tharaux, J Elion - expression of adhesion molecules on RBCs? - endothelial cells? - leukocytes?

7 Could HC affect cell adhesion? from JP Cartron SCADHESION project C Le Van Kim, PL Tharaux, J Elion - expression of adhesion molecules on RBCs? - endothelial cells? - leukocytes?

8 Number of a4b1/ reticulocyte % of reticulocytes with overexpression of a4b1 SS reticulocytes express high levels of the a4b1 integrin (and CD36) 4 3 a4b1 2 1 Controls (n=8) HC (n=19) VOC (n=18) NonVOC (n=23) Controls (n=2) HC (n=2) VOC (n=18) Non VOC (n=23) Odièvre et al, Haematologica, 28

9 Number of a4b1/ reticulocyte % of reticulocytes with overexpression of a4b1 HC treatment reduces the expression of the a4b1 integrin (and CD36) on SS reticulocytes 4 3 a4b Controls (n=8) HC (n=19) VOC (n=18) NonVOC (n=23) Before HC On HC Controls (n=2) HC (n=2) VOC (n=18) Non VOC (n=23) Before HC On HC Odièvre et al, Haematologica, 28

10 Number of VLA-4 / GPA+ cell at J2 in vivo results are mimicked in vitro on erythroid progenitors in culture VLA-4 (a4b1) No HC With HC Odièvre et al, Haematologica, 28

11 Cellular targets of hydroxycarbamide in SCD RBCs - Hb F production - adhesion molecules - decreased production of a4b1 integrin, CD36 UMR 665

12 Mechanisms of sickle red blood cell adhesion: impact of HC treatment Epinephrine β2-ar HC PKA camp Sickle Red Blood Cell Gauthier et al, J Biol Chem 25 α4β1 integrin El Nemer et al, Blood 27 Lu/BCAM Endothelial cells Lu/BCAM Adhesion Less adhesion Laminin α5 Odièvre et al, Haematologica 28 Bartolucci et al, Blood 21 Abnormal cell-cell interactions in SCD are triggered by signalling events HC diminishes cell adhesion by inhibiting Lu/BCAM phosphorylation, independently of its expression level

13 Cellular targets of hydroxycarbamide in SCD RBCs - Hb F production - adhesion molecules - decreased production of a4b1 integrin, CD36 - decreased phosphorylation of Lu/BCAM UMR 665

14 Could HC affect cell adhesion? from JP Cartron SCADHESION project C Le Van Kim, PL Tharaux, J Elion - expression of adhesion molecules on RBCs? - endothelial cells? - leukocytes?

15 Travelling distance (µm) Emmanuelle Verger Microcinematic recording of RBCs submitted results dynamics on treated or untreated ECs RBC trajectories Time (s) 75 cells per experiment are individually traced at 2 msec intervals for each treatment condition 5 SS patients + 5 controls = 3. individual kinetics

16 mean advanced velocity (µm/s) Velocities of interacting (rolling?) SS-RBCs are lower than those of AA-RBCs greater interaction HPMEC *** *** NT cyt Emmanuelle Verger unpublished results RBC type/treatment of EC

17 mean advanced velocity (µm/s) HU treatment increases velocities of interacting (rolling?) RBCs reduces transient interactions HPMEC + HC 8 7 *** *** *** *** Emmanuelle Verger unpublished results NT HC cyt cyt+hc RBC type/treatment of EC

18 adherent RBC number /mm² AA-RBCs vs SS-RBCs firm adhesion on EC+/- HU (1dyne/cm 2 flow) * * basal inflammatory RBC type AARBC SSRBC AARBC SSRBC NT NT Emmanuelle Verger, unpublished results

19 adherent RBC number /mm² AA-RBCs vs SS-RBCs firm adhesion on EC+/- HU (1dyne/cm 2 flow) * * basal inflammatory + HC RBC type AARBC SSRBC AARBC SSRBC HC treatment NT HC NT HC After HC treatment of CE, adhesion potential of SS-RBCs is equivalent to that of AA-RBCs Emmanuelle Verger, unpublished results

20 Could HC affect cell adhesion? from JP Cartron SCADHESION project C Le Van Kim, PL Tharaux, J Elion - expression of adhesion molecules on RBCs? - endothelial cells: decreased adhesion - leukocytes?

21 Mechanism of action of HC on endothelial cells Sickle reticulocyte Laurance et al, Pharmacogenet Genomics 21 Haematologica 211 HC TSP-1 vwf PECAM-1 AMP PDE α4β1 integrin Less adhesion Adhesion Lu/BCAM Verger et al, submitted Chaar et al, submitted camp PKA AC HC inhibits the adhesive recruiting potential of endothelial cells by ATP modulating membrane adhesion Endothelial proteins cells and their activation state via phosphodiesterase activation

22 Cellular targets of hydroxycarbamide in SCD RBCs - Hb F production - adhesion molecules Endothelial cells - decreased adhesion vascular tone? UMR 665

23 ET-1(pg/ml) % of expression ET-1(pg/ml) HC also decreases endothelin-1 production by endothelial cells in culture Brun et al, 23, Pharmacogenomics J. mrna 12 Protein * p<.5 (n=5) 1 6 * * 8 4 * * 2 Control HC Cyto + HC NT HC Cyto Cyto + HC HC HC+Cyto TrHBMEC cells Incubation time : 48h HC ( M) HUVEC cells: identical results UMR 665

24 ET-1 (pg/ml) ET-1 (pg/ml) In vivo HU decreases ET-1 plasmatic levels Lapouméroulie et al, 25, Hematologica longitudinal follow up (two 8 year old SS girls) 14 months 16 months ,6 2 1,6 2 1,2 15 1,2 15,8 1,8 1,4 5, months months Decrease of plasmatic ET-1 does not correlate with HbF induction UMR 665

25 Cellular targets of hydroxycarbamide in SCD RBCs - Hb F production - adhesion molecules Endothelial cells - decreased adhesion - decreased production of endothelin-1 vasoconstriction UMR 665

26 Could HC affect cell adhesion?? from JP Cartron SCADHESION project C Le Van Kim, PL Tharaux, J Elion - expression of adhesion molecules on RBCs? - endothelial cells? - leukocytes?

27 HC normalizes L-selectin expression and H 2 2 production by PMNs of SCD patients in vivo Benkerrou et al Blood, ** 1 ** 8 controls (n=11) 6 4 ** ** severe SS patients (n=17) HU treated (n=9) H 2 2 production L-selectin by whole blood PMNs stimulated with TNFa and fmlp expressed at the surface of fmlp-stimulated PMNs UMR 665

28 Cellular targets of hydroxycarbamide in SCD RBCs - Hb F production - adhesion molecules Endothelial cells - adhesion molecules - endothelin-1 Polymorphonuclear neutrophils - activation UMR 665

29 Conclusions HC has a pleiotropic action in SCD HC decreases deoxy HbS polymerisation - HbF expression - RBC hydration HC decreases cellular adhesion to endothelium - proadhesive RBCs - adhesion properties of ECs - PMN activation HC decreases vasoconstrictive stimulus - ET-1

30 Paris Guadeloupe Pointe-à-Pitre UMR 665 Institut national de la santé et de la recherche médicale Réunion

Adhésion à l endothélium dans la drépanocytose

Adhésion à l endothélium dans la drépanocytose Jacques Elion Départment de Génétique et INSERM UMR 763 Hôpital Robert Debré, 75019 Paris et CHU de Pointe à Pitre, 97139 Les Abymes Centre de Référence Francilien