European Society of Gene and Cell Therapy (ESGCT)
The XVth Annual Congress of the European Society of Gene and Cell Therapy
held in Rotterdam, The Netherlands, 27-30 October 2007

Kick-Off / Plenary Session: Presented Sunday, 28 October 2007 at ESGCT 2007

Preliminary Data from the First Hematopoietic Stem Cell Gene Therapy Trial with Lentiviral Vector
Demonstrate Expression of the Therapeutic Protein in High Percentage of Lymphocytes and Monocytes in
Two Patients with X-Linked Adrenoleukodystrophy

Nathalie Cartier1,2,3; Salima Hacein-Bey-Abina4,5; Gabor Veres6; Michel Vidaud1,7; Liliane Dal-Cortivo4,5; Laure
Caccavelli4,5; Nizar Malhaoui8; Véronique Kiermer9,*; Denice Mittelstaedt9,†; Andrew Simmons10; Céline Bellesme3;
Françoise Audat4,5; Stéphane Blanche8; Pierre Charnaud10; Muriel Audit11; Bruno L’homme1,2,13; Jing- Chao Zhao-
Emmonet1,2,13; Serge Fichelson14; Françoise Pflumio14; Anne Dubart-Kupperschmitt14; Rachel Salzman15; Amber
Salzman16; Pierre Bougnères3; Alain Fischer5,8; Marina Cavazzana-Calvo4,5; Patrick Aubourg1,2,3 1

INSERM U745, 2Faculty of Pharmacy, Université René Descartes, and 3Department of Pediatric Endocrinology and
Neurology, 13Hôpital Saint-Vincent de Paul, Paris, France; 4Department of Biotherapies, 5U768, and 8Unité
d’Immunologie et Hématologie Pédiatrique, Hôpital Necker- Enfants Malades, Paris, France; 6Applied Genetic
Technology Corporation, Alachua, FL, USA; 10R&D Development, 9Cell Genesys, Inc., South San Francisco, CA,
USA; 11Institut Pasteur, CNRS-URA 3015, Paris, France; 12Généthon, Evry, France; 14Department of Hematology,
U567, Institut Cochin, Paris, France; 15The StopALD Foundation, Houston, TX, USA; 16The StopALD Foundation and
GlaxoSmithKline, Philadelphia, PA, USA; *Present address: Nature Methods, New York, NY, USA; †Present address:
San Diego, CA, USA

We report preliminary results in two children with cerebral X-linked adrenoleukodystrophy (ALD) who received in
September 2006 and January 2007 hematopoietic stem cell (HSC) gene therapy using a HIV1-derived lentiviral
vector. We have previously shown that the cerebral demyelination associated with cerebral ALD can be stopped or
reversed within 18 months by allogeneic HSC transplantation. For the current HSC gene therapy procedure,
mobilized peripheral blood CD34_ cells were transduced ex vivo for 18 hr with a non-replicative HIV1- derived
lentiviral vector (provided by Cell Genesys, Inc.) expressing the ALD cDNA under the control of the MND promoter,
and in the presence of Il-3, SCF, Flt3-ligand, MGDF, and CH-296 retronectine. Transduced cells were frozen to
perform replication-competent lentivirus (RCL) assays. After thawing and prior to reinjection, 50% and 30%,
respectively, of transduced CD34_ cells expressed the ALD protein with a mean of 0.7 and 0.6 copies of integrated
provirus/cell. Transduced CD34_ cells were infused to ALD patients after full myeloablation with cyclophosphamide
and busulfan.

Hematopoietic recovery occurred at day 15 post-transplant, and the procedure was uneventful. The percentage of
corrected lymphocytes and monocytes in the peripheral blood of treated patients remained stable from day 30 to the
last follow-ups. From 25% to 30% (Patient P1, 9 months after transplant) and 20% (Patient P2, 41/2 months after
transplant) of CD14_, CD3_, CD19_, and CD3_CD56_ cells expressed the ALD protein (0.4 integrated provirus
copy/cell). Tests assessing vector-derived RCL and vector mobilization were negative up to the last follow-ups. These
early results support that: (1) ex vivo HSC gene therapy using HIV1-derived lentiviral vector is not associated with the
emergence of RCL and vector mobilization; (2) a high percentage of hematopoietic progenitors were transduced
expressing ALD protein in the short term; (3) no early evidence of selective advantage of the transduced ALD cells or
clonal expansion was observed; and (4) HSC gene therapy appears to have short-term neurological effects
comparable with allogeneic HSC transplantation.

Sponsored by INSERM and conducted under an R&D collaboration with Cell Genesys, Inc., South San Francisco,
CA.

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