Efficient and nontoxic adenoviral purging method for autologous transplantation in breast cancer patients.
Tumor cell contamination of clinical grafts is a major concern in autologous hematopoietic stem cell transplantation because these contaminating cells can contribute to relapse. In the present work, we use a suicide gene therapy approach that successfully accomplishes the two main goals of any purging strategy: highly efficient elimination of contaminating tumor cells and preservation of the engraftment capability of the hematopoietic progenitor cells. Human CD34(+) cells spiked with breast cancer cells were infected with an adenoviral vector encoding the cytosine deaminase transgene (Ad-CMV-CD). In vitro, transduction with Ad-CMV-CD followed by exposure to 400 micro M 5-fluorocytosine resulted in complete elimination of clonogenic contaminating tumor cells without affecting the clonogenic potential of the human hematopoietic CD34(+) cells. Transplantation of nonobese diabetic/LtSz-scid/severe combined immunodeficient (NOD/SCID) mice with nonpurged contaminated grafts and purged contaminated grafts, allowed us to test the safety and efficacy of our procedure in two independent purging experiments. Hematopoietic engraftment kinetics as well as the quantity and quality of human engraftment were not affected by the purging therapy. Results showed a significant difference in survival between the nonpurged group (28%) and the purged group (100%; P = 0.012). Moreover, highly sensitive histological and molecular analyses confirmed the absence of tumor cells in the recipients of purged marrow. In contrast, metastatic tumors were detected in animals that received nonpurged grafts. We anticipate that this strategy will result in a safe and efficacious hematopoietic graft product for autologous transplantation for patients with multiple forms of epithelial cancers.
Lillo
Rosa
R
Laboratorio de Histocompatibilidad y Biología Molecular, Centro de Transfusión de Madrid, 28009 Madrid, Spain.
Ramírez
Manuel
M
Alvarez
Angela
A
Santos
Silvia
S
García-Castro
Javier
J
Fernández de Velasco
Jaime
J
Avilés
María José
MJ
Gómez-Pineda
Alfonso
A
Díez
José Luis
JL
Balas
Antonio
A
Vicario
José Luis
JL
Bueren
Juan Antonio
JA
García-Sánchez
Félix
F
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D016465:Bone Marrow Purging / Q000379:methods*; D001943:Breast Neoplasms / Q000473:pathology* / Q000628:therapy*; D043525:Cytosine Deaminase; D005260:Female; D005437:Flucytosine / Q000493:pharmacokinetics; D015316:Genetic Therapy / Q000379:methods*; D018380:Hematopoietic Stem Cell Transplantation / Q000379:methods*; D006801:Humans; D008297:Male; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D009700:Nucleoside Deaminases / Q000235:genetics / Q000378:metabolism; D014407:Tumor Cells, Cultured
D005437:Flucytosine; D009700:Nucleoside Deaminases; D043525:Cytosine Deaminase