A technology platform to assess multiple cancer agents simultaneously within a patient's tumor.

A fundamental problem in cancer drug development is that antitumor efficacy in preclinical cancer models does not translate faithfully to patient outcomes. Much of early cancer drug discovery is performed under in vitro conditions in cell-based models that poorly represent actual malignancies. To address this inconsistency, we have developed a technology platform called CIVO, which enables simultaneous assessment of up to eight drugs or drug combinations within a single solid tumor in vivo.

Modeling promising nonmyeloablative conditioning regimens in nonhuman primates.

Minimal conditioning or even no conditioning would be the preferred preparation for most gene therapy applications for nonmalignant diseases. However, reduced intensity conditioning (RIC) regimens in patients with nonhematologic malignancies have not led to long-term engraftment unless a selective advantage was present for the transplanted donor cells. Similar findings have also been observed in a number of large animal studies.

No evidence of clonal dominance after transplant of HOXB4-expanded cord blood cells in a nonhuman primate model.

Umbilical cord blood transplant continues to increase in prevalence as a treatment option for various hematopoietic and immune disorders. Because of the limited number of cells available in a single cord blood unit, investigators have explored methods of increasing cell dose before transplant, including overexpression of the homeobox B4 (HOXB4) transcription factor. We have previously reported the development of leukemia in several nonhuman primate (NHP) subjects transplanted with HOXB4-expanded bone marrow cells at approximately 2 years posttransplant.

CD34(+) expansion with Delta-1 and HOXB4 promotes rapid engraftment and transfusion independence in a Macaca nemestrina cord blood transplant model.

Umbilical cord blood (CB) transplantation is a promising therapeutic approach but continues to be associated with delayed engraftment and infections. Here, we explored in our macaque CB transplant model expansion and engraftment kinetics of cells expanded with the combination of HOXB4 and Delta-1. CB cells were divided into two equal fractions; one fraction was transduced with HOXB4 yellow fluorescent protein (YFP) and expanded on control OP9 cells, and the other was transduced with HOXB4 green fluorescent protein (GFP) and expanded on Delta-expressing OP9 cells (OP9-DL1).

Hematopoietic stem cell expansion facilitates multilineage engraftment in a nonhuman primate cord blood transplantation model.

The use of umbilical cord blood for allogeneic transplantation has increased dramatically over the past years. However, the limited number of cells available in a single cord blood unit remains a serious obstacle. Here, we wished to establish a nonhuman primate cord blood transplantation model that would allow us to test various hematopoietic stem cell expansion and gene therapy strategies.

Hematopoietic stem cell expansion and gene therapy.

Hematopoietic stem cell (HSC) gene therapy remains a highly attractive treatment option for many disorders, including hematologic conditions, immunodeficiencies including human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS), and other genetic disorders such as lysosomal storage diseases. In this review, we discuss the successes, side-effects and limitations of current gene therapy protocols. In addition, we describe the opportunities presented by implementing ex vivo expansion of gene-modified HSC, as well as summarize the most promising ex vivo expansion techniques currently available.

Differential effects of HOXB4 and NUP98-HOXA10hd on hematopoietic repopulating cells in a nonhuman primate model.

Expansion of hematopoietic stem cells (HSCs) is beneficial in settings where HSC numbers are limited, such as cord blood transplantation. The human homeobox transcription factor HOXB4 has been shown to enhance stem cell expansion in several experimental models. We have shown previously that HOXB4 overexpression in monkey CD34(+) cells has a dramatic effect on expansion and engraftment of short-term repopulating cells.

Efficient generation of nonhuman primate induced pluripotent stem cells.

Induced pluripotent stem (iPS) cells have great potential for regenerative medicine and gene therapy. Thus far, iPS cells have typically been generated using integrating viral vectors expressing various reprogramming transcription factors; nonintegrating methods have been less effective and efficient. Because there is a significant risk of malignant transformation and cancer involved with the use of iPS cells, careful evaluation of transplanted iPS cells will be necessary in small and large animal studies before clinical application.

Combination of HOXB4 and Delta-1 ligand improves expansion of cord blood cells.

Umbilical cord blood (UCB) is an attractive cell source for hematopoietic cell transplantation (HCT). Here we examine whether the combination of homeobox B4 (HOXB4) and Delta-1 ligand (DL) synergize when used together. Monkey and human UCB CD34(+) cells were transduced with a HOXB4-expressing gammaretroviral vector and cultured with DL.

Cocal-pseudotyped lentiviral vectors resist inactivation by human serum and efficiently transduce primate hematopoietic repopulating cells.

Lentiviral vectors are established as efficient and convenient vehicles for gene transfer. They are almost always pseudotyped with the envelope glycoprotein of vesicular stomatitis virus (VSV-G) due to the high titers that can be achieved, their stability, and broad tropism. We generated a novel cocal vesiculovirus envelope glycoprotein plasmid and compared the properties of lentiviral vectors pseudotyped with cocal, VSV-G, and a modified feline endogenous retrovirus envelope glycoprotein (RD114/TR).

Concurrent blockade of alpha4-integrin and CXCR4 in hematopoietic stem/progenitor cell mobilization.

The important contributions of the alpha4 integrin VLA-4 and the CXCR4/SDF-1 axis in mobilization have been demonstrated and thereby, these pathways can be suggested as rational targets for clinical stem cell mobilization in the absence of cytokine use. alpha4-blockade alone (in humans, macaques and mice), or genetic ablation of alpha4-integrin in mice, provides reproducible, but modest mobilization. Similarly, CXCR4 blockade with small-molecule antagonists mobilizes hematopoietic stem cells in all three species, but at least with the established single-injection schedule, the mobilization efficiency is marginally sufficient for clinical purposes.