Category Archives: Gene therapy

Stem Cells FDA Oversight
Celia Witten, M.D., Ph.D., Director, Office of Cellular, Tissue, Gene Therapy Center for Biologics Evaluation Research, Food Drug Administration (FDA) For more information on the 2014...

By: Alliance for Regenerative Medicine

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Stem Cells & FDA Oversight - Video

A new variation of gene therapy raises hopes for a safe and effective long-term treatment for X-linked severe combined immunodeficiency syndrome (SCID-X1), a life-threatening heritable disorder.

The research was produced by a collaborative research team from Dana-Farber/Boston Children's Cancer and Blood Disorders Center, along with other institutions participating in an international clinical trial that involved boys from the United States and France.

SCID-X1, dubbed bubble boy disease after a patient who lived for 12 years in a sterile bubble, is a rare genetic disorder that hinders the ability of individuals to combat infections. Because the disease is carried in an X-chromosome recessive pattern, the disorder occurs almost only in males. The resulting mutations inactivate a gene called IL-2 receptor gamma (IL2RG), severely weakening immune system functions. Left untreated, individuals who inherit the disorder usually die within a year.

Previous gene therapy trials conducted in Europe over a decade ago promised dramatic progress, until a quarter of patients developed leukemia about two to five years following treatment. Scientists found that the previously used vectorthe device for transporting the correct gene in therapyinadvertently activated oncogenes, which can cause cancer.

In this new study, the vector in use is a self-inactivating gammaretrovirus, which has a specific sequence deleted that basic research had implicated in the process of inappropriate activation of oncogenes, David A. Williams, chief of the hematology/oncology department at Boston Children's Hospital, wrote in an email.

Of the nine patients who underwent the treatment, eight had survived between 12 and 38 months after treatment. One boy died from a severe infection he was fighting at the time he enrolled in the study.

A single round of therapy restored normal disease-fighting T cell count300 cells or more per microliter of bloodin six of the eight patients. One patient underwent a second round of treatment and remains healthy despite a low cell count. The eighth patient received a hematopoietic stem cell transplant after the therapy led to less than optimal uptake of the virus and failed to stimulate T-cell production, according to Williams.

We feel the surrogate assays for safety look excellent and are very encouraged, Williams said. However, because leukemia can take years to develop (and although some of our patients are now approaching 4 years of [follow-up]) we must be cautious and continue to follow these children closely.

Williams noted that the research was the result of positive collaboration between institutions.

Work by Sung-Yun Pai and Gigi Notarangelo, funding from [Boston Childrens Hospital] (and other childrens hospitals) and [the National Institute of Health] were essential for success, he said. This is the first international collaborative trial in stem cell gene therapy, which was critical for success due [to the] rarity of [this] disease.

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With Collaboration, Scientists Test Gene Therapy for 'Bubble Boy Disease'

PHILADELPHIA A new form ofgene therapyfor boys with X-linked severe combined immunodeficiency syndrome (SCID-X1), a life-threatening condition also known as bubble boy disease, appears to be both effective and safe, according to an international clinical trial with sites inBoston, Cincinnati, Los Angeles, London, and Paris.

Early data published in theNew England Journal of Medicinesuggests that the therapy may avoid the late-developing leukemiaseen in a quarter of SCID-X1 patients in previous gene-therapy trials in Europe that took place more than a decade ago. Left untreated, boys with SCID-X1 usually die of infection before their first birthday.

The lab of coauthorFrederic Bushman, PhD, professor of Microbiology, from thePerelman School of Medicine at the University of Pennsylvania, carried out the deep DNA sequencing on patient specimens to track and verify distributions of integration sites of the vector.The vector used in the new trial was engineered to remove molecular signals implicated in cancers in the first trial.

Eight of nine boys recruited to date to the present trial are alive between 12 and 38 months after treatment, with no SCID-X1-associated infections. The gene therapy alone generated functioning immune systems in seven of eight boys. Genetic studies showed that the new viral vector did not lead to vector insertions near known cancer-causing genes, raising cautious hopes about the vector's long-term safety.

We showed that fewer cells accumulated with integration sites near cancer genes in the second trial, suggesting that the adverse properties had indeed been engineered out, explains Bushman So far there are no clinical adverse events in the present trial -- the integration site data has suggested improved safety.

The modified vector created for the current trial is a self-inactivating gammaretrovirus, designed to deliver its payload effectively while minimizing the chance of inadvertently turning on oncogenes that could lead to leukemia.

The core question of the trial was whether the new self-inactivating viral vector could safely and successfully shuttle a gene called theIL-2 receptor gamma(IL2RG) subunit into the patients' hematopoietic stem cells. In boys born with SCID-X1, mutations render theIL2RGgene inactive, robbing the children of the ability to produce a functional immune system.

For more information, see theDana-Farber/Boston Children's Cancer and Blood Disorders Centersnews release.

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Penn Medicine is one of the world's leading academic medical centers, dedicated to the related missions of medical education, biomedical research, and excellence in patient care. Penn Medicine consists of theRaymond and Ruth Perelman School of Medicine at the University of Pennsylvania(founded in 1765 as the nation's first medical school) and theUniversity of Pennsylvania Health System, which together form a $4.3 billion enterprise.

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New Gene Therapy for "Bubble Boy" Disease Appears to be Safe, Effective

TIME Health Genetics Gene-Therapy Trial Shows Promise Fighting Bubble Boy Syndrome The immune system-related disease affects about 1 in 100,000 babies each year

A new gene-therapy treatment is showing promise in treating a rare and severe congenital condition that involves extreme immune-system deficiencies.

Bubble boy syndrome, an X-linked condition, takes its name from a famous case in which an affected boy, vulnerable to infection, lived inside a plastic bubble that protected him from the worlds germs. Outside of such sterile environments, babies with the syndrome seldom live longer than a year, the Wall Street Journal reports.

The condition has for decades bested medical researchers, despite occasional bouts of optimism hope for one previous gene-therapy treatment was felled when some recipients developed leukemia.

Gene-therapy treatment works, essentially, by replacing unperforming genes with functional ones. Dysfunctional cells are removed from the childs immune system and exposed to a genetically engineered virus that can reprogram the cells to function properly, explains Reuters. Those cells are then reinserted back into the patient.

In the earlier treatment, the virus to which the cells were exposed apparently activated a part of their genetic code that leads to leukemia, Reuters says.

But initial results reported in the New England Journal of Medicine show that none of the nine babies from the U.S. and Europe who received the latest treatment are exhibiting any signs of cancer.

Of the nine infant participants in the research who were between 4 and 10 months old when they began receiving the therapy eight were still alive 16 to 43 months later, without living in a protective bubble. (The ninth child died four months after treatment began from an earlier infection he had been fighting.)

Out of the eight boys still living, the treatment upped blood T-cell levels, rebuilding the immune system, of seven. In the case of the eighth child, the treatment did not rebuild his immune system, but a successful stem-cell transplant has kept him in improved health, Reuters reports.

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Gene-Therapy Trial Shows Promise Fighting Bubble Boy Syndrome

Date:

October 8, 2014

Source:

NIH/National Institute of Allergy and Infectious Diseases

Summary:

Gene therapy using a modified delivery system, or vector, can restore the immune systems of children with X-linked severe combined immunodeficiency (SCID-X1), a rare, life-threatening inherited condition that primarily affects boys, researchers have discovered.

Researchers have found that gene therapy using a modified delivery system, or vector, can restore the immune systems of children with X-linked severe combined immunodeficiency (SCID-X1), a rare, life-threatening inherited condition that primarily affects boys. Previous efforts to treat SCID-X1 with gene therapy were initially successful, but approximately one-quarter of the children developed leukemia two to five years after treatment. Results from a study partially funded by the National Institute of Allergy and Infectious Diseases (NIAID), a component of the National Institutes of Health (NIH), suggest that the new vector is equally effective at restoring immunity and may be safer than previous approaches.

In SCID-X1, mutations in a specific gene prevent the development of infection-fighting T cells. The standard therapy for SCID is transplantation of blood-forming stem cells, but some patients lack a suitable donor. In gene therapy, doctors remove stem cells from the patient's bone marrow, use a vector to insert a corrected gene and then return the corrected cells to the patient. Scientists suspect that the vectors used in earlier studies may have activated genes that control cell growth, contributing to leukemia.

In the current study, nine boys with SCID-X1 underwent gene therapy using a vector engineered by the study researchers. Seven boys developed functional T cells at levels comparable to those seen in previous studies and have remained healthy for one to three years after treatment. Analyses of the children's T cells suggest that the new vector causes fewer genomic changes that could be linked to leukemia. Researchers will continue to monitor the boys for leukemia development. Of the two other boys, one died of a pre-existing viral infection shortly after receiving the therapy, and one failed to develop corrected T cells and was given a stem cell transplant from an unrelated donor.

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Gene therapy shows promise for severe combined immunodeficiency

Joint research projects by NUIG and the Mayo Clinic will focus on a number of key strategic areas, including adult stem-cell therapy, gene therapy, biomaterials and biomedical engineering, the two institutes have said. Illustration: Getty

NUI Galway and the Mayo Clinic in the US plan to collaborate on clinical trials using regenerative medicine, following the signing of a memorandum of understanding between the two institutes.

The joint research projects will focus on a number of key strategic areas, including adult stem-cell therapy, gene therapy, biomaterials and biomedical engineering, the two institutes have said.

The Mayo Clinic and NUIGs Regenerative Medicine Institute have worked closely with each other for a number of years.

Both have licensed cell manufacturing facilities, and student and staff exchange programmes between Galway and the US will continue.

Welcoming the agreement, NUIG president Dr Jim Browne has noted that his university has Irelands only facility licensed to produce stem cells for human use.

A new clinical and translational research facility for conducting clinical trials with patients will be complete in early 2015, he said.

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NUI Galway in joint stem cell project with Mayo Clinic

Many human diseases are caused by defective genes.

All of these diseases are caused by a defect at a single gene locus. (The inheritance is recessive so both the maternal and paternal copies of the gene must be defective.) Is there any hope of introducing functioning genes into these patients to correct their disorder? Probably.

Other diseases also have a genetic basis, but it appears that several genes must act in concert to produce the disease phenotype. The prospects of gene therapy in these cases seems far more remote.

It is a disease of young children because, until recently, the absence of an immune system left them prey to infections that ultimately killed them.

Once the virus has infected the target cells, this RNA is reverse transcribed into DNA and inserted into the chromosomal DNA of the host.

The first attempts at gene therapy for SCID children (in 1990), used their own T cells (produced following ADA-PEG therapy) as the target cells.

In June of 2002, a team of Italian and Israeli doctors reported on two young SCID patients that were treated with their own blood stem cells that had been transformed in vitro with a retroviral vector carrying the ADA gene. After a year, both children had fully-functioning immune systems (T, B, and NK cells) and were able to live normal lives without any need for treatment with ADA-PEG or immune globulin (IG). The doctors attribute their success to first destroying some of the bone marrow cells of their patients to "make room" for the transformed cells.

Nine years later (August 2011) these two patients are still thriving and have been joined by 28 other successfully-treated children most of whom no longer need to take ADA-PEG.

Gene therapy has also succeeded for 20 baby boys who suffered from another form of severe combined immunodeficiency called X-linked SCID because it is caused by a mutated X-linked gene encoding a subunit called c (gamma-c) of the receptor for several interleukins, including interleukin-7 (IL-7).

IL-7 is essential for converting blood stem cells into the progenitors of T cells. [View]. Boys with X-linked SCID can make normal B cells, but because B cells need T-helper cells to function, these boys could make neither cell-mediated nor antibody-mediated immune responses and had to live in a sterile bubble before their treatment.

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Gene Therapy I - RCN Corporation

A gene-therapy experiment at Fred Hutchinson Cancer Research Center only involved a handful of brain-tumor patients, and on average, extended their lives by months, not years.

Even so, it was the first real progress in 30 years for patients with glioblastoma, the most common and most aggressive type of primary brain tumor the type that killed U.S. Sen. Edward Kennedy within 15 months of diagnosis.

I think this is actually one of those proof-of-concept milestones, said Dr. Stanton Gerson, director of the Case Comprehensive Cancer Center at Case Western Reserve University in Cleveland, who was not involved in the study. This is the very first clinical validation that all that science made sense.

The new approach, led by Dr. Hans-Peter Kiem and Dr. Jennifer Adair at Fred Hutch in Seattle, was published Friday in The Journal of Clinical Investigation.

It began with the usual therapy for such tumors powerful chemotherapy combined with a drug that disables a protein that makes some of these tumors particularly resistant to chemotherapy. More than half the patients with glioblastomas, including all seven patients enrolled in the study, have such a protein, Kiem said.

The protein-disabling drug, benzylguanine, is critically important because it allows chemotherapy to attack the tumor. But the drug also damages bone marrow, killing blood cells so people are left vulnerable to infection and bleeding, he said. For that reason, patients typically can receive only one or two cycles of chemotherapy.

The gene-therapy approach involved taking the patients stem cells and engineering them to become resistant to benzylguanine, so their blood cells werent damaged by the drug. When the stem cells were returned to the patients, their blood was protected but their tumors were left vulnerable to the chemotherapy.

Better protected against infection and bleeding, the seven patients in the study were able to receive more cycles of chemotherapy.

We can sensitize the tumor, while the blood cells are resistant, Kiem said. That is the trick.

Typical median survival for glioblastoma patients with the tumor-protecting protein is less than 13 months. The patients in this study, on average, survived 20 months, and all survived beyond one year. This is quite remarkable, he said.

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Experiment at Fred Hutch raises hopes in battling brain tumors

A major hurdle in gene therapy is the efficient integration of a corrected gene into a patient's genome without mutating off-target sites. In a paper published today in Genome Research, scientists have used CRISPR/Cas genome editing technology to seamlessly and efficiently correct disease-causing mutations in cells from patients with -thalassemia.

-thalassemia results from inherited DNA mutations in the hemoglobin beta (HBB) gene, resulting in reduced HBB expression in red blood cells and, in the most severe forms, anemia. The only established curative treatment is hematopoietic stem cell transplantation; however, this treatment requires a matched donor. Gene therapy, which delivers a corrected copy of a gene into patient cells, could bypass the need for a donor. Previous attempts using a virus to randomly insert a normal gene into the genome has been successful in one -thalassemia patient, but the long-term effect of viral insertion is not yet known.

To correct HBB mutations directly in a patient's genome, researchers first generated induced pluripotent stem cells, or iPSCs, from skin cells of patients. The real breakthrough came when they applied CRISPR/Cas9 to precisely engineer a double strand DNA break at the HBB locus in these cells, allowing a donor plasmid with the corrected sites to be efficiently integrated, thus replacing the mutated sites. The donor plasmid also contained selectable markers to identify cells with corrected copies of the gene. These selectable markers were subsequently removed with transposase and a second round of selection, generating a seamless, corrected version of HBB in the patient's genome.

Importantly, the researchers could differentiate the corrected iPSCs into mature blood cells, and these blood cells showed restored expression of hemoglobin. However, much work is needed before these cells could be transplanted back into a patient for treating -thalassemia. "Although we and others are able to differentiate iPSCs into blood cell progenitors as well as mature blood cells, the transplantation of the progenitors into mouse models to test them has so far proven very difficult," said senior author Yuet Wai Kan from the University of California, San Francisco. "I believe it will take quite a few more years before we can apply it in a clinical setting."

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The above story is based on materials provided by Cold Spring Harbor Laboratory. Note: Materials may be edited for content and length.

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Seamless gene correction of beta-thalassemia mutations in patient-specific cells

WASHINGTON No batteries required: Scientists are developing a biological pacemaker by injecting a gene into the hearts of sick pigs that changed ordinary cardiac cells into a special kind that induces a steady heartbeat.

The study, published on Wednesday, is one step toward developing an alternative to electronic pacemakers, which are implanted in 300,000 Americans a year.

There are people who desperately need a pacemaker but can't get one safely, said Dr. Eduardo Marban, director of the Cedars-Sinai Heart Institute in Los Angeles, who led the work. This development heralds a new era of gene therapy that one day might offer them an option.

Your heartbeat depends on a natural pacemaker, a small cluster of cells it's about the size of a peppercorn, Marban said that generates electrical activity. Called the sinoatrial node, it acts like a metronome to keep the heart pulsing at 60 to 100 beats a minute or so, more when you're active. If that node quits working correctly, hooking the heart to an electronic pacemaker works very well for most people.

But about 2 percent of recipients develop an infection that requires the pacemaker to be removed for weeks until antibiotics wipe out the germs, Marban said. And some fetuses are at risk of stillbirth when their heartbeat falters, a condition called congenital heart block.

For more than a decade, teams of researchers have worked on a biological alternative that might help those kinds of patients, trying such approaches as using stem cells to spur the growth of a new sinoatrial node.

Marban's attempt uses gene therapy to reprogram a small number of existing heart muscle cells so that they start looking and acting like natural pacemaker cells instead.

Because pigs' hearts are so similar to human hearts, Marban's team studied the approach in 12 laboratory pigs with a defective heart rhythm.

They used a gene called TBX18 that plays a role in the embryonic development of the sinoatrial node. Working through a vein, they injected the gene into some of the pigs' hearts in a spot that doesn't normally initiate heartbeats and tracked them for two weeks.

Two days later, treated pigs had faster heartbeats than control pigs who didn't receive the gene, the researchers reported in the journal Science Translational Medicine. That heart rate automatically fluctuated, faster during the day. The treated animals also became more active, without signs of side effects.

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Trying gene therapy to create biological pacemaker