Inducible Caspase 9 Suicide Gene to Improve the Safety of Allodepleted T Cells After Haploidentical Stem Cell Transplantation

Authors

Siok-Keen Tey, Center for Cell and Gene Therapy, Baylor College of Medicine, The Methodist Hospital and Texas Children’s Hospital, Houston, Texas
Gianpietro Dotti, Center for Cell and Gene Therapy, Baylor College of Medicine, The Methodist Hospital and Texas Children’s Hospital, Houston, Texas
Cliona M. Rooney, Center for Cell and Gene Therapy, Baylor College of Medicine, The Methodist Hospital and Texas Children’s Hospital, Houston, Texas
Helen E. Heslop, Center for Cell and Gene Therapy, Baylor College of Medicine, The Methodist Hospital and Texas Children’s Hospital, Houston, Texas
Malcolm K. Brenner, Center for Cell and Gene Therapy, Baylor College of Medicine, The Methodist Hospital and Texas Children’s Hospital, Houston, Texas

Publication Date

8-2007

Journal

Biol Blood Marrow Transplant. 2007 August; 13(8): 913–924.

DOI

10.1016/j.bbmt.2007.04.005

PMID

17640595

PMCID

PMC2040267

PubMedCentral® Posted Date

October 2007

PubMedCentral® Full Text Version

Author MSS

Published Open-Access

no

Keywords

Apoptosis, Caspase 9, Feasibility Studies, Genes, Transgenic, Suicide, Genetic Vectors, Graft vs Host Disease, Haplotypes, Hematopoietic Stem Cell Transplantation, Hematopoietic Stem Cells, Humans, Immunotherapy, Adoptive, Lymphocyte Transfusion, Retroviridae, T-Lymphocytes, Transduction, Genetic, Transplantation, Homologous

Abstract

Addback of donor T cells following T cell-depleted stem cell transplantation (SCT) can accelerate immune reconstitution and be effective against relapsed malignancy. After haploidentical SCT, a high risk of graft-versus-host disease (GVHD) essentially precludes this option, unless the T cells are first depleted of alloreactive precursor cells. Even then, the risks of severe GVHD remain significant. To increase the safety of the approach and thereby permit administration of larger T cell doses, we used a suicide gene, inducible caspase 9 (iCasp9), to transduce allodepleted T cells, permitting their destruction should administration have adverse effects. We made a retroviral vector encoding iCasp9 and a selectable marker (truncated CD19). Even after allodepletion (using anti-CD25 immunotoxin), donor T cells could be efficiently transduced, expanded, and subsequently enriched by CD19 immunomagnetic selection to >90% purity. These engineered cells retained antiviral specificity and functionality, and contained a subset with regulatory phenotype and function. Activating iCasp9 with a small-molecule dimerizer rapidly produced >90% apoptosis. Although transgene expression was downregulated in quiescent T cells, iCasp9 remained an efficient suicide gene, as expression was rapidly upregulated in activated (alloreactive) T cells. We have demonstrated the clinical feasibility of this approach after haploidentical transplantation by scaling up production using clinical grade materials.

Comments

PMC2040267