Department of Pediatrics

Texas Children’s Hospital

Baylor College of Medicine

Houston, TX

WILSON RESEARCH PROJECT

Current Research Interests

Dr. Hurwitz investigates the use of adenoviral vectors to transfer therapeutic genes within the ocular environment and to examine the immune response as it pertains to gene therapy. His hypothesis is that gene therapy protocols for both ocular and non-ocular disorders can be optimized by understanding how the unique ocular environment influences the efficacy of gene therapy.

Retinoblastoma (Rb), an ocular cancer that affects young children, can be caused either by spontaneous growth of a tumor in one eye or by an inherited mutation that often causes tumors in both eyes. Removal of the eye (enucleation) with the tumor is often curative but ophthalmologists are opting for local therapies to control small tumors or systemic chemotherapy to control larger tumors. Sometimes small pieces of tumor break off to form vitreous seeds. Developing alternative treatments that could potentially preserve vision and reduce the risk of developing other cancers is important.

Dr. Hurwitz has completed the first clinical trial using suicide gene therapy (a method of forcing the tumor cells to produce a protein that converts a drug to a locally toxic agent) to treat children with advanced Rb. The successful reduction of vitreous seeds has encouraged him to continue his laboratory initiatives to improve this innovative therapy. Additionally he would like to better understand the differences between invasive and non-invasive tumors and to identify and characterize the Rb tumor stem cell. He is also interested in developing gene therapy options for retinal degenerative disorders such as Stargardt Disease. His strategy for either application of gene therapy uses a special nonpathogenic virus to deliver the correct genetic material to selected cells in the eye.

Plans for 2024

Dr. Hurwitz’s hypothesis is that gene therapy protocols for both ocular and non-ocular disorders can be optimized based on understanding how the unique ocular environment influences the efficacy of the gene therapy treatment. In 2024, Dr. Hurwitz will continue to analyze the contributions of the versican G1 and G3 domains and to examine the alternative, non-invasive delivery approach that uses microwafers loaded with nanoparticles to deliver therapeutic drugs or genes with the goals of further enhancing efficacy and reducing toxicity, with the intention of preparing and submitting manuscripts describing these results.

Specific Aims: To continue investigating the use of adenoviral vectors to
transfer therapeutic genes to the ocular environment and to examine the immune response as it pertains to gene therapy.

Aim 1) The vector systems that we have developed for suicide gene therapy for retinoblastoma and for gene replacement approaches for the treatment of Stargardt Disease are being used to explore mechanisms of adenoviral-mediated transgene expression unique to the ocular environment.

Aim 2) The immune response to adenoviral-mediated gene therapy for children with retinoblastoma was monitored and shown to be dose dependent. Innovative methods to reduce the dose of viral vector required to achieve therapeutic effect are being developed. These aims are continuations and extensions of the on-going research supported by the Retina Research Foundation in 2023.

Progress in 2023

Dr. Hurwitz previously published an association of the vitreous component hyaluronan with the enhanced expression of potentially therapeutic genes transferred by adenoviral vectors. Hyaluronan alone does not account for the entire effect observed. Versican is a component of vitreous that binds hyaluronan and is made up of three domains called G1 and G3, separated by a chondroitin-binding domain. The effects of these domains have been examined using expression constructs that span the known functional elements that may affect transgene expression. G1 and G3 have been shown to have a complex interplay in regulating gene expression. G1 also delivers hyaluronan to the cell surface where it further enhances gene expression. These constructs may be useful in designing more efficient vectors and delivery systems to optimize gene therapy outcomes and limit toxicities including immune consequences.

Dr Hurwitz has also been exploring the potential of using microwafers loaded with
nanoparticles to deliver therapeutic drugs or genes directly to the eye without the need
for surgery or injections. He has shown that chemotherapeutic agents can be
delivered locally to the eye and treat retinoblastoma in a murine model of the disease.

Specific Aims: Dr. Hurwitz continued investigations of the use of adenoviral vectors to transfer therapeutic genes to the ocular environment and to examine the immune response as it pertains to gene therapy. Aim 1). The vector systems that have been developed for suicide gene therapy for retinoblastoma and for gene replacement approaches for the treatment of Stargardt Disease are being used to explore mechanisms of adenoviral-mediated transgene expression unique to the ocular environment. Aim 2). The immune response to adenoviral-mediated gene therapy for children with retinoblastoma was monitored and shown to be dose dependent. Innovative methods to reduce the dose of viral vector required to achieve therapeutic effect are being developed.

Progress in 2022 

Dr. Hurwitz and his co-investigator, Mary Hurwitz, PhD continued their exploration of the contribution of versican to the enhancement of adenoviral-mediated transgene expression by defining the minimal G1 domain that is responsible for the effect. In addition, versican contains a G3 domain that contains sequences that allow interaction with known cellular signaling receptors. The laboratory team plans to continued studies to determine the contribution of G3 interactions to the cellular response to transgenes. They continued their examination of the alternative, noninvasive delivery approach that uses microwafers loaded with nanoparticles to deliver therapeutic drugs or genes with the goals of further enhancing efficacy and reducing toxicity.

Progress in 2021

Dr. Hurwitz previously published an association of the vitreous component hyaluronan with the enhanced expression of potentially therapeutic genes transferred by adenoviral vectors. Hyaluronan alone does not account for the entire effect observed. Subsequently, his team began to explore the contribution of another vitreous component, the large hyaluronan-binding proteoglycan versican. They explored the G1 and G3 domains of versican using expression constructs that span the known functional elements that may affect transgene expression. These constructs may be useful in designing more efficient vectors and delivery systems to optimize gene therapy outcomes and limit toxicities including immune consequences. They also explored the potential of using microwafers loaded with nanoparticles to deliver therapeutic drugs or genes directly to the eye without the need for surgery or injections

Specific Aims: The specific aims are continuations and extensions of the on-going research currently supported by the Retina Research Foundation. Dr. Hurwitz’s team  continued our investigations of the use of adenoviral vectors to transfer therapeutic genes to the ocular environment and to examine the immune response as it pertains to gene therapy. 1) The vector systems that we have developed for suicide gene therapy for retinoblastoma and for gene replacement approaches for the treatment of Stargardt Disease are being used to explore mechanisms of adenoviral-mediated transgene expression unique to the ocular environment. 2) The immune response to adenoviral-mediated gene therapy for children with retinoblastoma was monitored and shown to be dose dependent. Innovative methods to reduce the dose of viral vector required to achieve therapeutic effect are being developed.

Progress in 2020

Dr. Hurwitz previously published an association of the vitreous component hyaluronan with the enhanced expression of potentially therapeutic genes transferred by adenoviral vectors. Hyaluronan alone does not account for the entire effect observed. Subsequently, we began to explore the contribution of another vitreous component, the large hyaluronan-binding proteoglycan versican.  His preliminary evidence indicated that five expression constructs that span the G1 domain isolating and combining the known functional elements may affect transgene expression. In addition, he has a construct that expresses the EGF-like motif in the carboxyterminal G3 domain. These constructs may be useful in designing more efficient vectors and delivery systems to optimize gene therapy outcomes and limit toxicities including immune consequences.

Dr. Hurwitz’s research was published in a paper entitled: “Inhibitors of metalloprotease, γ-sectretase, protein kinase C and Rho kinase inhibit wild-type adenoviral replication,” in PLOS One.  2020 Publications

Progress in 2019

In 2019, based upon previously published association of the vitreous component hyaluronan, Dr. Hurwitz began to explore the contribution of another vitreous component, the large hyaluronan-binding proteoglycan versican.  Initial results of experiments verifying a contribution of the versican G1 domain have also been published.  Dr. Hurwitz continued to examine the biochemical pathways influenced by both the amino-terminal G1 domain and the carboxyl terminal G3 domain by creating expression constructs that may be useful in designing more efficient vectors and delivery systems to optimize gene therapy outcomes and limit toxicities including immune consequences.

Progress in 2018

In 2018, Dr. Hurwitz continued to examine the biochemical pathways influenced by the amino-terminal G1 domain by creating expression constructs that may be useful in designing more efficient vectors and delivery systems to optimize gene therapy outcomes and limit toxicities including immune consequences.

Progress in 2017

We have previously published an association of the vitreous component hyaluronan with the enhanced expression of potentially therapeutic genes transferred by adenoviral vectors. Hyaluronan alone does not account for the entire effect observed. In 2017, Dr. Hurwitz began exploration of the contribution of another vitreous component, the large proteoglycan versican. The initial results of experiments verifying a contribution of the versican G1 domain were epublished in July and published in full in September 2017 (Akinfenwa, et al, J Biol Chem, (2017) 292:14381-14390). The studies included the analysis of biochemical pathways influenced by the G1 domain and may provide useful in designing more efficient vectors and delivery systems to optimize gene therapy outcomes and that limit toxicities including immune consequences.

Progress in 2016

Dr. Hurwitz has developed novel, non-invasive microwafers that can deliver nanoparticles containing drugs or gene-expressing plasmids to the posterior chamber of the eye including to the retina. He hypothesizes that this system would be ideal for treating Rb. These microwafers are small, flexible discs similar to contact lenses, containing wells on one surface that can be filled with nanoparticles that carry a drug or gene of the doctor’s choice. Preliminary in vitro studies using nanoparticles that deliver doxorubicin demonstrate that nanoparticles can deliver this chemotherapeutic agent to Y79 Rb cells and cause cell death in a dose-dependent manner.

Progress in 2015

1) Preliminary results are consistent with the hypothesis that the hyaluronan-binding proteoglycan versican is the component of vitreous that enhances adenoviral-mediated transgene expression. 2) Preliminary data shows that when expression of the protein SKAP2 is decreased, the proliferation of Rb cells increases. 3) Dr. Hurwitz has found that inhibition of Src kinase activity in vitro can decrease the amount of viral vector necessary to kill retinoblastoma cells.

Progress in 2014

Dr. Hurwitz has previously reported that hyaluronan (HA), a major component of vitreous, enhances adenoviral-mediated transgene expression through interactions with its receptor CD44. Dr. Hurwitz is currently exploring whether versican, a complex protein, can explain the hyaluronan-CD44 interaction that he has previously observed.

Dr. Hurwitz has isolated approximately 30 primary cell lines from children who presented with Rb, and he has determined the exact RB1 mutations that resulted in their disease for most of these children. 3) Dr. Hurwitz determined the dose of vector that achieved 50% killing of the tumor cells.

Progress in 2013

Dr. Hurwitz has completed the first clinical trial that used suicide gene therapy (a method of forcing the tumor cells to produce a protein that converts a drug to a locally toxic agent) to treat children with advanced Rb. The successful reduction of vitreous seeds has encouraged him to continue his laboratory initiatives to improve this innovative therapy. Additionally, he would like to better understand the differences between invasive and non-invasive tumors and to identify and characterize the Rb tumor stem cell. Dr. Hurwitz is also interested in developing gene therapy options for retinal degenerative disorders such as Stargardt Disease. His strategy for either application of gene therapy uses a special nonpathogenic virus to deliver the correct genetic material to selected cells in the eye.

Progress in 2012

Dr. Hurwitz has completed the first clinical trial that used suicide gene therapy (a method of forcing the tumor cells to produce a protein that converts a drug to an agent that is toxic to the tumor cells) to treat children with advanced Rb and the successful results have encouraged him to continue his laboratory initiatives to improve this innovative therapy.

Retinoblastoma (Rb), an ocular cancer that affects young children, can be caused either by spontaneous growth of a tumor in one eye or by an inherited mutation that often causes tumors in both eyes. Removal of the eye with the tumor is often curative, but ophthalmologists are opting for laser, cryo- or radiation therapies to control small local tumors or systemic chemotherapy to control larger tumors with the goal of saving vision. However, children treated with chemotherapy or radiation therapy have a significantly increased risk of developing other types of cancer later in life.

Some disorders that cause retinal degeneration and blindness such as Stargardt Disease are also associated with errors in genetic material. These defects are manifest in the abnormal structure or function of proteins responsible for normal vision. If the mutation(s) in the affected gene is known, replacing the defective gene with a normally functioning gene could slow or even halt the degeneration.

Dr. Hurwitz’s laboratory continued their investigations of the use of adenoviral vectors to transfer therapeutic genes to the ocular environment and to examine the immune response as it pertains to gene therapy.

1. The vector systems that they have developed for suicide gene therapy for retinoblastoma and for gene replacement approaches for the treatment of Stargardt Disease are used to explore mechanisms of adenoviral-mediated transgene expression unique to the ocular environment.

2. To better target these vectors to retina cells and the retinoblastoma tumors derived from them, the origin of retinoblastoma tumor cells and the mechanisms of retina-derived cell proliferation are being explored.

3. The immune response to adenoviral-mediated gene therapy for children with retinoblastoma was monitored and shown to be dose dependent. Innovative methods to reduce the dose of viral vector required to achieve therapeutic effect are being developed.

Progress in 2011

The vector systems that Dr. Hurwitz has developed for suicide gene therapy for retinoblastoma and for gene replacement approaches for the treatment of Stargardt Disease are being used to explore mechanisms of adenoviral-mediated transgene expression unique to the ocular environment.

Dr. Hurwitz studies the potential use of gene therapy for the treatment of ocular diseases. He has shown that a novel treatment for retinoblastoma using suicide gene therapy is safe and possibly effective in children. The mechanism of adenoviral-mediated transgene expression in the ocular environment is being explored with goals of providing future molecular targets to modulate adenoviral-mediated gene therapy for both retinoblastoma and retinal degenerative diseases and possibly of controlling adenovirus infection in general.

Dr. Hurwitz is studying the cellular origin of retinoblastoma and the differences between invasive and non-invasive forms of this disease. Dr. Hurwitz has demonstrated that an embryonic mouse model of retinoblastoma, a cancer of the eye that occurs in children, can be created. This model conclusively shows that proliferating, undifferentiated retinal cells can form tumors.  A small percentage of cells that express the neural stem cell related protein CD133 can be isolated from a cell line that was created from this murine tumor.

These CD133 positive cells can preferentially recreate the retinal tumor in mice and this tumor appears identical to primary retinoblastoma tumors in both mice and children.  Therefore, a proliferating tumor cell that expresses the neural stem cell marker CD133 is responsible for retinoblastoma tumor initiation in a mouse model of the disease.