The Vector
Editorial Team
Karen Bulaklak, PhD – Editor, The Vector
Jon Brudvig, PhD – Associate Editor, The Vector
Jessica Schneller, PhD – Junior Editor, The Vector
Inside This Issue
Leadership Message
Breaking Through
From Molecular Therapy
Society News
Career Center
Public Policy
Industry News
Leadership Message
International Members.......
Hello, ASGCT Members,
I hope you’re doing well. For those of you who don’t know me, my name is Jayandharan Rao, and I am currently serving as chair of ASGCT’s Global Outreach Committee. I am an associate dean of research and development and professor in the department of biological sciences and bioengineering at the Indian Institute of Technology, Kanpur. I wanted to let you all know about some of our recent international efforts that you can share with colleagues, watch on demand, and keep in mind to register for in the future.
The Global Outreach Committee was formed just over three years ago to address the challenge of fostering equitable access to gene and cell therapies in low-resource settings. In that short time, the committee has been a driving force for new international programming and opportunities. I’d encourage you to watch the Around the World series, which is a collection of half-day events held in different regions of the world. In Brazil, South Africa, India, and Lebanon, investigators have been committed to bringing novel therapies to those in need and to developing domestic manufacturing capacity. This series will continue in 2023!
I am proud to continue to include international audiences into the Society’s programming. At the 26th Annual Meeting, there will be an international networking reception to bring together attendees from different areas of the world. This Global Gathering will help to build new relationships and will foster exchange of knowledge and advances in the field. As the premier gene therapy membership association, it’s important that ASGCT membership is accessible to all. I’m pleased to share that we’re now offering economy-based membership rates. All the benefits of membership are available at reduced rates to individuals living in countries with low- and middle-income economies.
Finally, his month, ASGCT is holding a virtual course for faculty at universities or medical schools in sub-Saharan Africa called Introduction to Gene Therapy for Educators. In partnership with Muhimbili University of Health and Allied Sciences, this certificate-awarding course will equip participants with the necessary knowledge and skills to educate students on the advances in clinical gene therapy. The course is four weeks and covers gene therapy methods, clinical trials, ethics, regulatory aspects, and the role of patient advocacy organizations. The faculty participating in the course are being trained by ASGCT members to implement gene therapy education into their university and medical school curricula and thus inform the next generation of clinicians and scientists. The committee hopes to continue to host similar programs that will increase awareness of the state of the gene therapy field in low- and middle-income countries. Keep an eye on the Global Outreach page of ASGCT’s website for information on future opportunities.
I look forward to seeing you in Los Angeles for the 2023 ASGCT Annual Meeting!
Jayandharan Rao, PhD
Chair, ASGCT Global Outreach Committee
Breaking Through
A truncated reverse transcriptase enhances prime editing by split AAV vectors
Gao Z, Ravendran S, Mikkelsen, NS, Haldrup J, Cai H, Ding X, Paludan SR, Thomsen MK, Mikkelsen JG, and Bak RO
DOI: https://doi.org/10.1016/j.ymthe.2022.07.001
Summary by Karen Bulaklak, PhD
Prime editing is a new CRISPR-based gene editing technology that has taken the stage for the next generation of genetic therapies. Compared to previous CRISPR approaches, prime editing can achieve specific edits at a target locus in the genome while avoiding double stranded breaks and a separate donor template. The system is composed of three essential pieces: (1) a prime editor (PE), which is a fusion of the Cas9-nickase and a mutant Moloney murine leukemia virus (M-MLV) reverse transcriptase (RT), (2) a prime editing guide RNA (pegRNA) that is a template for the desired edit, and (3) a nicking guide RNA (ngRNA). While there is much excitement around its versatility and the therapeutic possibilities with this approach, more optimization is needed to ensure sufficient delivery of all the necessary components in common in vivo delivery vehicles, such as AAV. Recent work by Gao et al at Aarhus University describes several strategies to make the prime editing technology more compatible with packaging constraints for in vivo application.
The researchers began with a PE cassette ~6.4 kb in size, which surpassed the 5 kb limit of AAVs and required splitting into dual AAV vectors. To reduce the size, they first attempted to modify the RT within the PE gene cassette. They screened several RT variants from retrovirus and bacterial origin, only to find that the original M-MLV and xenotropic-murine-leukemia-related virus (XMRV) RTs were functional. Furthermore, the XMRV RT induced lower editing than the M-MLV RT at the locus screened. Next, the group worked to codon optimize the existing PE in hopes of finding a better version for continuing their engineering efforts. Out of six codon optimized versions, a variant dubbed “PECO” exhibited the highest protein expression and editing across three different targets. The group then attempted to modify the RNase H domain within the RT. They hypothesized that this domain was expendable since it would only be useful for RNA template degradation. After testing cassettes with deletions of the RNase H domain and additional truncations of the RT, they found that omitting the entire RNase H domain and an additional 150 bp of the RT did not affect the editing efficiency or type of edits compared to the full-length PECO, allowing for a size reduction of 621 bp without any loss of activity. With this new “PECO-Mini,” Gao et al next focused on the optimal strategy for splitting the PE cassette via inteins, testing several different known split sites. Depending on the position of these sites in the cassette, efficacy could be compromised. While the split cassettes did not perform as well as the full-length PECO-Mini, they chose the cassette that could be split in a way to give the most flexibility for switching out regulatory elements (Rma 674-675) and showed about 75% activity compared to the unsplit PE. With these alterations, they next evaluated AAV packaging of the PECO-Mini cassette and found that titers were improved compared to the PECO. In addition, editing in vitro was higher with PECO-Mini, suggesting that more functional viral particles were produced. Similarly, lentiviral packaging experiments with all-in-one constructs containing either PECO-Mini or PECO demonstrated higher titers and greater editing with the PECO-Mini. Finally, an in vivo experiment was performed to disrupt the PCSK9 gene using the newly characterized PECO-Mini delivered via AAV. Treatment with PECO-Mini induced 1-5% prime editing, demonstrating feasibility of prime editor delivery with AAV.
In summary, Gao et al show that a culmination of alterations to decrease the size of the original PE gene cassette can maintain activity while allowing for efficient viral vector packaging. With such improvements, we will hopefully be closer to bringing prime editing to the clinic.
From Molecular Therapy
Call for papers: Exploiting extracellular vesicles as therapeutic agents
The editors of the Molecular Therapy family of journals are pleased to announce a concomitant series of special issues across the journal family focused on the identification, characterization, and standardization of EV technology and the exploitation of the latter as therapeutic agents and biomarkers for the treatment of the gamut of human disease. Submit by Dec. 1! Learn more.
Latest MT issues: Check out the most recent issues of these Molecular Therapy family journals:
Society News
Apply for NORD Rare Disease Research Grants by Nov. 14
The National Organization for Rare Disorders (NORD) opened requests for proposal (RFPs) for three rare disease research grants related to Autoimmune Polyglandular Syndrome Type 1 (APS-1), Levy-Yeboa Syndrome (LYS), and Megacystis Microcolon Intestinal Hypoperistalsis Syndrome (MMIHS). Grants will be awarded to qualified researchers to initiate small scientific research studies or clinical trials, the results of which could be used to obtain funding from the NIH, FDA, or other funding agencies, or to attract a corporate sponsor. Learn more and apply by Nov. 14.
Watch the 2022 Policy Summit On Demand Through Oct. 27
If you attended the Policy Summit last month and want to revisit any of the sessions, you can access all of them on demand on the virtual platform through Oct. 27. If you didn't attend, you can still register through that date to get access! Don't forget to fill out the evaluation to let us know what you thought.
Register for Free Events This Month
Career Center
Are you looking for a job in the field of gene and cell therapy? Check out the new ASGCT Career Center for great opportunities with industry, government, and academic organizations. Sign up to receive alerts for open jobs in your area.
If you're from a recruiting institution, advertise in the Featured Jobs section to target the 5,000+ audience of The Vector.
Featured Jobs
Public Policy
2022 Policy Summit Tackles Intertwined Legislative and Regulatory Issues
ASGCT works tirelessly to advocate for policies that support the work of our members and the field. During the fourth annual Policy Summit, we welcomed nearly 300 in-person and virtual attendees to address the most important policy topics for the CGT field. Read our blog for an in-depth summary of each expert panel.
This year’s Policy Summit kept an eye to the future, integrating the ways in which regulatory and legislative policy can help advance the field. There was an emphasis on patient safety as well as access, efficacy, and commercialization. Wilson Bryan, MD, director of CBER OTAT, highlighted the office’s staffing challenges but also sounded hopeful about the opportunities for additional resources under PDUFA VII. Meanwhile John Coster, PhD, director of the division of pharmacy at the Center for Medicare and Medicaid Services (CMS) presented a keynote talk on the role of CMS and specific Medicaid considerations for the coverage and reimbursement of CGT. Other sessions tackled issues as broad as diversity in the CGT field, including for clinical trial participation and the workforce; the accelerated approval pathway; and CMC considerations for CGT products.
All sessions at the Policy Summit were recorded and are available on the virtual platform. You can still register and access all the on-demand content through Oct. 27!
Public Meeting with FDA Oct. 19 Will Focus on Potency Assays for CGTs
Join us Oct. 19 for a public meeting with FDA on potency assays for cell and gene therapies.
Cohosted with the Alliance for Regenerative Medicine (ARM), the virtual meeting will be held from 9 a.m. to 4 p.m. (ET). You can register using this link to the main room or this link to the breakout room, and bring your questions for a brief Q&A during the event.
We’ll post a full agenda closer to the event.
Apply for Congressional Policy Fellowship Oct. 15
Starting Oct. 15, apply for ASGCT's inaugural Congressional Policy Fellowship! In partnership with AAAS, we'll select one applicant for a one-year policy fellowship in legislative offices on Capitol Hill beginning in the fall of 2023. Fellows will provide high-quality, science-based, independent guidance to federal policy makers and elevate awareness of the Society among policymaking circles. Fellows must be an ASGCT member with a doctoral degree looking to learn more about the intersection of science and policy. A summary of application materials and FAQ are available on our website, so take a look and get ready to apply.
This opportunity will help you expand your professional network and develop new, legislative skills from the ground up. Dr. Diane Berry, former AAAS fellow and current chair of the ASGCT Government Relations Committee, recently wrote a blog detailing her experience as a fellow and how it shaped her career, helping her develop a more holistic view of the cell and gene therapy field.
First Gene Therapy Approved for CALD
On Sept. 16, FDA granted accelerated approved to the gene therapy elivaldogene autotemcel (eli-cel) to slow the progression of the neurodegenerative dysfunction early, active cerebral adrenoleukodystrophy (CALD) in boys from four to 17 years old. Eli-cel, which will be marketed as SKYSONA, is now the second lentiviral vector gene therapy for patients with severe genetic diseases in the U.S. and the first for CALD.
The approval of eli-cel, following closely on the heels of approval for bluebird bio’s beti-cel, is a significant advancement for the field. It gives patients an alternative to allogeneic hematopoietic stem cell transplantation, which can be associated with serious complications, especially in patients without a human leukocyte antigen (HLA) matched donor. ASGCT President Hans-Peter Kiem, MD, PhD, shared more detail about the approval and what it means for CALD patients.
Members Speak at House CAR T-Cell Therapy Briefing
ASGCT thanks the Congressional Cancer Caucus co-chairs, Congressmen Higgins (D-NY), Kilmer (D-WA), Fitzpatrick (R-PA), and Kelly (R-PA), for supporting CAR T-cell therapies at a recent bipartisan briefing on innovative approaches to cancer care. ASGCT members and leaders explained the basics of gene and cell therapy, the patient experience, access considerations, and the outlook and pipeline of CAR T treatments. You can watch the briefing on ASGCT’s YouTube channel.
ASGCT is encouraged by the productive dialogue with representatives and their staff on these important issues and will be following up with individual offices later this year.
FDA User Fee Program Reauthorized Through 2027
Late last month, the Health, Education, Labor, and Pension (HELP) and Energy and Commerce (E&C) Committees, along with House and Senate leadership, committed to reauthorizing FDA’s medical product user fees for the full five years as part of a short-term government funding package. The bill passed the Senate (72-25) on Sept. 29 and passed the House (230-201) the following day, largely along party lines. President Biden then signed the bill, averting a government and FDA shutdown.
Draft text of the continuing resolution (CR) to fund the government through mid-December was released Sept. 26 and included the reauthorization of PDUFA VI as well as FDA’s three other human medical product user fee programs through 2027. It also incorporates all changes to program financing and the new commitment letters negotiated between the Agency and the regulated industries. The CR does not include any FDA policy riders that were a part of the Food and Drug Act of 2022 or the FDA Safety and Landmark Advancements Act, such as reforms to the accelerated approval pathway or clinical trial diversity provisions. It did include short-term reauthorizations of minor FDA programs. When the CR expires Dec. 16, other FDA policy provisions previously associated with the user fee bills mentioned above, PREVENT Pandemics Act, and CURES 2.0, will be fair game for inclusion in the December package.