A little more than a decade ago, seven patients with hemophilia Ba disease caused by a mutation on the F9 gene that prevents patients from forming crucial clotting proteinsvolunteered to be the first humans to receive a gene therapy delivered using an adeno-associated virus as a vector. This particular treatment didnt move past the Phase 1/2 trial because, while it was deemed safe, the patients did not sustain expression of the gene. But two other gene therapies based on an adeno-associated virus (AAV), Luxturna for rare forms of blindness and Zolgensma for spinal muscular atrophy, have since been approved by the US Food and Drug Administration (FDA), and several pharmaceutical companies are now pursuing regulatory approval of AAV-carried gene therapies for hemophilia B.
Recently, scientists followed up with four of those original patients. In a study published in Molecular Therapy in September, they report that the men are still free of any worrisome toxicities related to the treatment. The study wasnt all good news, though. The team also found that after all these years, the men still had elevated levels of AAV-neutralizing antibodies. That means that if an AAV gene therapy is approved to treat their illness, they likely wont be able to benefit from itthe antibodies would chew up the vector before it could insert the corrective gene.
Administration of an AAV gene therapy is essentially a vaccine against AAV, says Lindsey George, a hematologist at the Childrens Hospital of Philadelphia who led the research. Hers was not the first study to identify antibodies as a problem for those receiving AAV gene therapies, but it is the first to show that elevated titers can last this long. This role of AAV neutralizing antibodies is huge, says George, as it stands to undermine the effectiveness of gene therapies.
Because AAVs are viruses, the human immune system creates antibodies upon exposure that recognize and neutralize them in subsequent encounters. Sometimes patients have neutralizing antibodies in their blood before ever having received a gene therapy because theyre exposed to AAVs in the environment.
The ability to effectively modulate the antibody-mediated immune response could make AAV gene therapies far more effective for far more patients than they are now.
Along with high levels of antibodies to the specific AAV vector that theyd receivedAAV2the patients Georges team evaluated also had neutralizing antibodies to several other commonly used AAV vectors, namely, AAV5 and AAV8, she tells The Scientist.
Andrew Davidoff, a pediatric surgeon at St. Jude Childrens Research Hospital who studies AAV gene therapies but was not involved in the study, says, This paper suggests that not only will they not be able to receive a second dose of vector of the same [type of AAV], but potentially even other [types].
If scientists can prevent antibodies from neutralizing the AAV, they would not only give patients like these another opportunity to receive a more effective dose of gene therapy, but it will expand the patients that we can treat with the therapy to include the 3050 percent of patients who have already been exposed to AAVs in the environment, says Giuseppe Ronzitti, who heads a lab focused on gene therapy research at Genethon.
But, Davidoff says, nobody has found a suitable solution yet that is likely to be accepted by patients. The body has evolved over millions of years, this immune system that helps fight off infections. So to overcome that, even temporarily, is not an easy task.
Some immunosuppressant drugs wont work if the body has already developed specific antibodies to a particular pathogen, such as AAV. Scientists are therefore testing combinations of different types of immunosuppressants they hope will prevent the body from attacking AAVs, but these are likely to come with major risks, chiefly, susceptibility to infection.
Another option is plasmapheresisa process in which a persons blood is removed from the body and the cells separated from the plasma so that they can be reinfused without the antibodies found in the plasmabut, like immunosuppressant drugs, the technique is nonspecific and comes with similar risks. Its a matter of risk-benefit with the continued immunosuppression, says Ronzitti.
So scientists have been looking for other ways to control the bodys response to these gene therapy vectors.
Ronzitti and his team recently proposed a solution in Nature Medicine. The scientists used the imlifidase (IdeS) protein, conditionally approved by the European Commission, to degrade immunoglobulin G (IgG) antibodies that are developed after the body encounters a specific antigen so that it can remember and target that antigen in the future, and thus might cause a patient to reject a transplanted kidney. IgG antibodies are responsible for the immune systems response to AAVs. Its a newer, less invasive alternative to plasmapheresis, Ronzitti tells The Scientist in an email.
The team injected monkeys with the IdeS protein before administering a dose of gene therapy targeting the liver. The treatment appeared safe, the monkeys levels of preexisting AAV antibodies went down, and the AAV vector successfully made its way to the liver. To model a scenario in which a patient would need more than one dose of gene therapy, the scientists administered an AAV gene therapy to another group of monkeys before giving them the IdeS protein to degrade the antibodies theyd developed in response, then readministered the gene therapy. Again, AAV antibodies diminished after the IdeS treatment and the second gene therapy dose was successfully delivered.
One drawback to the approach is that IgGs are the most prevalent type of antibody found in the blood, and destroying all of them may have undesirable side effects. In an attempt to develop a more targeted therapy, one group published a study in January demonstrating that a specialized version of plasmapheresis could reduce the levels of antibodies against human AAVs in mice to the point where a new gene therapy should be effective, without depleting all other immunoglobulins that formed in response to infections.
More recently, a team of researchers at the University of Pittsburgh Medical Center made use of CRISPR-Cas9 to increase the efficacy of AAV gene therapy in mice. Pathologist Samira Kiani and her team werent looking for ways to improve gene therapy, but instead were seeking to temporarily modulate immunity in hopes of changing the course of diseases such as septicemia, a precursor to sepsis that occurs when an infection makes its way to the blood. The researchers aimed to temporarily downregulate the Myeloid differentiation primary response 88(Myd88) gene, which would briefly dampen the immune response, and then remove the brakes.
The gene that we chose to target is known to a be a central gene for innate and adaptive immunity, says Kiani. It controls the production of IgG antibodies in response to AAV exposure, which provided a simple way to measure whether the strategy was effective. If the team administered an AAV to an animal shortly after it had received the CRISPR-Cas9 treatment, it should have a substantially lower antibody response to the virus.
First, they administered the CRISPR to tamp down Myd88 activity and measured a reduction in the expression of the Myd88 gene, as theyd expected. Then, the team used the technique to treat mice just before giving them a dose of AAV-based gene therapy that was designed to lower their cholesterol.
Weeks later, the researchers administered a second dose of the same AAV vector to determine if the temporary immunosuppression during the first dose had prevented the mice from making enough antibodies to thwart a second dose. The mice that were pretreated with the immune-modulating CRISPR showed lower levels of AAV-neutralizing antibodies and more dramatic responses to the cholesterol-lowering AAV treatment. The study was published in NatureCell Biologyin September.
If given prior to the administration of an AAV gene therapy, this approach would prevent the formation of new antibodies, so the patient could receive a second dose later, if needed, says Kiani. Given that the CRISPR treatment only prevents the development of antibodies temporarily, it shouldnt cause any long-term suppression of the rest of the immune system. On the flip side, because it doesnt clear existing antibodies, if the patients have already pre-existing antibodies [from natural exposure] this approach might not be the best approach.
All of the potential solutions have a long way to go, including still needing to be tested in human patients, but the ability to effectively modulate the antibody-mediated immune response could make AAV gene therapies far more effective for far more patients than they are now, says Ronzitti. The immune response to these vectors is quite a complex story, he says. But we are solving the issues one by one.
L. George et al., Long-term follow-up of the first in human intravascular delivery of AAV for gene transfer: AAV2-hFIX16 for severe hemophilia B,Molecular Therapy,doi:10.1016/j.ymthe.2020.06.001, 2020.
F. Moghadam et al., Synthetic immunomodulation with a CRISPR super-repressor in vivo,Nature Cell Biology,doi:10.1038/s41556-020-0563-3, 2020.
Read more here:
Thwarting AAV-Neutralizing Antibodies Could Improve Gene Therapy - The Scientist
- Krystal Biotech Inc (KRYS) Reports Strong Q4 and Full Year 2023 Financial Results - Yahoo Finance - February 27th, 2024
- New sickle cell gene therapies are a breakthrough, but solving how to pay their high prices is a struggle - CNBC - February 27th, 2024
- 10 gene therapy companies you should know about - Labiotech.eu - February 27th, 2024
- Former Penn employee sues Gene Therapy Program director, alleging 'unethical and illegal conduct' - The Daily Pennsylvanian - February 27th, 2024
- Gene therapy can't cure deafness because it doesn't need to be cured - The Philadelphia Inquirer - February 27th, 2024
- Fetal surgery expert Tippi MacKenzie shifts to in-utero gene therapy - STAT - February 27th, 2024
- Therapeutic Solutions International Files Patent on Facilitating Effects of JadiCells on Gene Therapy Mediated Cell ... - Business Wire - February 27th, 2024
- CU Anschutz Set to Launch Gene Therapy Trials for Heart Disorder - University of Colorado Anschutz Medical Campus - February 27th, 2024
- ICH targets cell and gene therapies, real-world data as topics ripe for harmonization - Regulatory Focus - February 27th, 2024
- Encoded Therapeutics Announces UK CTA Approval for Dravet Syndrome Gene Therapy Candidate ETX101 - Business Wire - February 27th, 2024
- Voyager Therapeutics Announces Selection of Gene Therapy Development Candidate for Friedreich's Ataxia in ... - GlobeNewswire - February 27th, 2024
- Therapeutic Solutions International Files Patent on Facilitating Effects of JadiCells on Gene Therapy Mediated Cell ... - The Bakersfield Californian - February 27th, 2024
- Ring Therapeutics, a Flagship gene therapy startup, lays off 20% of staff - STAT - February 27th, 2024
- Ed Silverman on new gene therapies, biosimilars, coffee, and more - STAT - STAT - February 27th, 2024
- Combatting HIV using gene therapy - Drug Target Review - February 27th, 2024
- NCDHHS working with federal government on increasing access to sickle cell disease treatment - WECT - February 27th, 2024
- Cell Therapy Weekly: FDA Approves First Cell Therapy For Solid Tumors - RegMedNet - February 27th, 2024
- Rejuvenate Bio Announces Gene Therapy-Mediated Partial Reprogramming Extends Lifespan and Reverses Age ... - Business Wire - February 27th, 2024
- New sickle cell therapy uses gene editing at MUSC | Health | postandcourier.com - The Post and Courier - February 27th, 2024
- Long-term and real-world safety and efficacy of retroviral gene therapy for adenosine deaminase deficiency - Nature.com - February 18th, 2024
- Gene therapy, blood transfusions, stool monitoring: The Sydneysiders trying to escape death - Sydney Morning Herald - February 18th, 2024
- Not too late to repair: gene therapy improves advanced heart failure in animal model - Baylor College of Medicine | BCM - February 18th, 2024
- Direct Administration of CRISPR-Cas9: Tools for Cell and Gene Therapy - Forbes - February 18th, 2024
- Gene therapy's promise seen in its success for AADC deficiency - AADC News - February 18th, 2024
- First Patient Randomized in AskBio Phase II Gene Therapy Trial for Congestive Heart Failure Treatment - Diagnostic and Interventional Cardiology - February 18th, 2024
- FDA to review expanded use of Sarepta Duchenne gene therapy - Yahoo Finance - February 18th, 2024
- How gene therapy can help treat a rare blood disorder - KUTV 2News - February 18th, 2024
- CRISPR gene therapy Casgevy secures approval in Europe - Pharmaceutical Technology - February 18th, 2024
- FDA Updates for the Week of Feb. 12, 2024: New Approvals, an Extended Review and Goal Dates Set - Managed Healthcare Executive - February 18th, 2024
- First Patient Randomized in AskBio Phase II Gene Therapy Trial for Congestive Heart Failure - Business Wire - February 18th, 2024
- Lisa Jarvis: A cure for some kinds of hearing loss? Gene therapies are getting closer - St. Paul Pioneer Press - February 18th, 2024
- Spinal Muscular Atrophy Market: Navigating Therapeutic Advances towards USD 5.6 Billion by 2034, with a CAGR of ... - Yahoo Finance - February 18th, 2024
- Crispr Therapeutics' Gene Therapy Wins EU Approval - TipRanks.com - TipRanks - February 18th, 2024
- Revolutionizing Gene Therapy: A Novel Technique for In Vivo CAR T Cells - Medriva - February 18th, 2024
- How Stella Vnook is 'infusing innovation' into cell therapies with Likarda's technology - BioPharma-Reporter.com - February 18th, 2024
- Using cancer's 'superpower' to boost T-cell therapies in mice - FierceBiotech - February 18th, 2024
- Parkinson's Disease Patient Identification and Education Will Need to Improve When New Disease Modifying ... - Yahoo Finance - February 18th, 2024
- CRISPR (CRSP) to Report Q4 Earnings: What's in the Cards? - Yahoo Finance - February 18th, 2024
- Gene Therapy: A Ray of Hope for Heart Failure Treatment | Health News - Medriva - February 18th, 2024
- Gene therapy trials restore hearing to children born deaf - The Hill - February 2nd, 2024
- Early Trial Success for Inherited Deafness Gene-Therapy - RegMedNet - February 2nd, 2024
- Sickle cell gene therapy first focus of Medicaid pay model - Modern Healthcare - February 2nd, 2024
- Beyond chemotherapy: Navigating the promise and perils of CAR-T therapy in pediatric cancer - BioPharma-Reporter.com - February 2nd, 2024
- Angiodema: Gene therapy blocks painful hereditary disorder - BBC - February 2nd, 2024
- FDA: Genome editing therapies may use accelerated approval pathway - Regulatory Focus - February 2nd, 2024
- CRISPR tech treats severe hereditary condition successfully - Interesting Engineering - February 2nd, 2024
- Gene Therapy Restores Hearing in Small Trial for Kids With Hereditary Deafness - Technology Networks - February 2nd, 2024
- Gene-based therapy may slow development of life-threatening heart condition - Medical Xpress - February 2nd, 2024
- Jaguar Gene Therapy Announces FDA Clearance of IND to Study JAG201 in a Genetic Form of Autism Spectrum ... - Business Wire - February 2nd, 2024
- Replacing the PKP2 gene prolongs survival in ARVC patients - Drug Target Review - February 2nd, 2024
- Cell and gene therapies top pharmaceutical industry trend to watch for 2024 - Pharmaceutical Technology - February 2nd, 2024
- Gene Therapy Restores Hearing in Children with Hereditary Deafness - The Hearing Review - February 2nd, 2024
- 2 Dutch among 10 "functionally cured" of hereditary swelling disease by new gene therapy - NL Times - February 2nd, 2024
- FDA publishes final industry guidance for CAR-T and gene therapies - PMLiVE - February 2nd, 2024
- Gene therapy cures hereditary deafness in two people - Advanced Science News - February 2nd, 2024
- Hearing Restored in Deaf Children in Gene Therapy Clinical Trial - Securities.io - February 2nd, 2024
- Vivet Therapeutics Receive 4.9 Million to Advance Development of Gene Therapy - European Pharmaceutical Manufacturer - February 2nd, 2024
- Adverum Biotechnologies will Host Webcast to Review LUNA Phase 2 Preliminary Efficacy and Safety Results on ... - GlobeNewswire - February 2nd, 2024
- Allogene parks Notch CARs, leaving one on the road - FierceBiotech - February 2nd, 2024
- Experimental gene therapy allows kids with inherited deafness to hear - The Associated Press - January 25th, 2024
- Gene-therapy breakthrough allows congenitally deaf children to hear Harvard Gazette - Harvard Gazette - January 25th, 2024
- Gene therapies restore hearing in several kids with inherited deafness - Livescience.com - January 25th, 2024
- Boy born deaf can hear for the first time thanks to a gene therapy procedure - NBC 6 South Florida - January 25th, 2024
- Gene therapy restores hearing in children with hereditary deafness - Medical Xpress - January 25th, 2024
- Children's Hospital of Philadelphia Performs First in U.S. Gene Therapy Procedure to Treat Genetic Hearing Loss - PR Newswire - January 25th, 2024
- Children's Hospital of Philadelphia uses gene therapy to help 11-year-old boy hear for 1st time - WPVI-TV - January 25th, 2024
- Breakthrough gene therapy treatment restores hearing in children born deaf - The Independent - January 25th, 2024
- Gene Therapy Administered Via Virus Cures Deafness in 11-Year-Old Boy - Futurism - January 25th, 2024
- 11-Year-Old Boy Hears For First Time Ever Thanks To Gene Therapy Breakthrough - IFLScience - January 25th, 2024
- Gene Therapy Deafness | National | caledonianrecord.com - The Caledonian-Record - January 25th, 2024
- Sickle cell gene therapy to be covered by Blue Cross insurers - Modern Healthcare - January 25th, 2024
- Experimental gene therapy allows kids with inherited deafness to hear - Jackson Hole News&Guide - January 25th, 2024
- Gene therapy allows 11-year-old boy to hear for the first time - Latest From ITV News - ITVX - January 25th, 2024
- Experimental Gene Therapy Allows Kids With Inherited Deafness To Hear - Southern Minnesota News - January 25th, 2024
- Joint US-China gene therapy trials restore hearing in 5 kids, a first - Interesting Engineering - January 25th, 2024
- Gene Therapy Deafness | Nation | The Daily News - Galveston County Daily News - January 25th, 2024
- In Draft Guidance for Cell and Gene Therapy Industry, FDA Broadens its Approach to Product Potency - Precision Medicine Online - January 25th, 2024
- Gene therapy helps restore hearing in children with hereditary deafness - Shropshire Star - January 25th, 2024
- Gene therapy breakthrough enables deaf boy to hear for the first time - The Week - January 25th, 2024
- FDA eyes collaborative review pilot for gene therapies - Regulatory Focus - January 17th, 2024