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For children with Diamond-Blackfan Anemia (DBA) - an inherited condition defined by low red blood cell counts and limited progenitor cells in the bone marrow -  growth hormone (GH) therapy was found to increase the short stature of  patients -   a symptom not widely analyzed. 

Growth Hormone Therapy Effective at Increasing Anemics' Height During Childhood

Patient use of the 2 FDA-approved gene therapy products for sickle cell disease (SCD), Vertex Pharmaceuticals' and CRISPR Therapeutics’ 

 (exa-cel; marketed as Casgevy) and bluebird bio’s 

 (lovo-cel; marketed as Lyfgenia), in the commercial setting has remained low.

Despite the approval of both gene therapy products by the FDA occurring simultaneously on December 8, 2023, only 4 patients have begun treatment with lovo-cel in the commercial setting, while 20 patients are reported to have begun treatment with exa-cel. Alongside the number for lovo-cel, bluebird also pointed out that this year 4 patients have started on elivaldogene autotemcel (Lenti-D, Skysona), its marketed gene therapy for cerebral adrenoleukodystrophy, and 19 patients have started on betibeglogene autotemcel (beti-cel, Zynteglo), its marketed gene therapy for transfusion dependent thalassemia (TDT). As such, bluebird bio has reported 23 total cell collections for SCD/TDT gene therapies lovo-cel and beti-cel. The company expects that patient uptake of the 3 aforementioned therapies will continue to increase, with 85 patient starts expected across the therapies by the end of the year.

“We are seeing clear evidence that our commercial launch is accelerating, with over 20 cell collections completed in SCD and TDT to date in 2024, and more than 40 additional patients already scheduled to initiate the treatment journey for a bluebird gene therapy by the end of this year,” Andrew Obenshain, MBA, the chief executive officer of bluebird bio, said in a statement.

 “We are further encouraged by the commitment to provide patient access across both commercial and government payers, most recently conveyed through multiple positive Medicaid decisions and the growing number of published coverage policies for Lyfgenia, and we expect approximately 85 patient starts across our portfolio this year.”

Notably, unlike lovo-cel, exa-cel is indicated for both SCD and TDT. Since Vertex has not clarified the breakdown of patients treated with exa-cel for each disease, direct comparison is difficult. The approval in TDT came slightly later, with 

“Vertex delivered another strong quarter of revenue growth coupled with outstanding execution across the business, and we are increasing our full year product revenue guidance,” Reshma Kewalramani, MD, the chief executive officer and president of Vertex, said in an August 1, 2024, statement.

 “Our focus for the second half of the year remains on commercial execution in cystic fibrosis and the global launch of Casgevy, readying for the upcoming potential launches of the vanzacaftor triple in cystic fibrosis and suzetrigine in acute pain, while rapidly advancing a robust pipeline that is poised to deliver value for patients and shareholders for the long term.”

Beyond gene therapy for SCD and TDT, uptake of 

hemophilia gene therapies has also been slow

. Although BioMarin’s valoctocogene roxaparvovec (val-rox, marketed as Roctavian) was approved in June 2023, the first patient outside of clinical trials 

 until December 2023, at the Center for Inherited Bleeding Disorders (CIBD) in California.

 Just this month, BioMarin announced that 

 with regard to val-rox, with the company now mainly focusing on distributing the gene therapy in the United States, Germany, and Italy, the 3 countries in which it has been approved for use by relevant regulatory authorities and is reimbursed.

 UniQure and CSL Behring’s hemophilia B gene therapy, etranacogene dezaparvovec (marketed as Hemgenix), which was 

, has also been slow to be embraced by patients.

“We haven't seen a lot of patients dosed yet,” Steven W. Pipe, MD, a professor of pediatric hematology/oncology at CS Mott Children’s Hospital, told 

 regarding Hemegenix earlier in 2024. “And I don't think that’s related to either the enthusiasm of the clinicians or the patients, but really just the mechanics of how to deliver this in the clinical space, as opposed to the research trials... We've seen that a lot of the hemophilia treatment center sites have got their components together, their infrastructure and personnel so that they can actually start delivering this in the commercial setting. And so, I'm really looking forward to seeing this making a difference in patients' lives in a real world setting.”

REFERENCES
1. bluebird bio reports second quarter 2024 results and highlights operational progress and 2024 guidance. News release. bluebird bio, Inc. August 14, 2024. Accessed August 15, 2024. https://investor.bluebirdbio.com/news-releases/news-release-details/bluebird-bio-reports-second-quarter-2024-results-and-highlights
2. Stock dive for bluebird as sickle cell gene therapy lags behind Vertex rival. News article. Anna Bratulic. FirstWord Pharma. August 14, 2024. Accessed August 15, 2024. https://firstwordpharma.com/story/5885598
3. Vertex announces US FDA approval of CASGEVY™ (exagamglogene autotemcel) for the Treatment of Transfusion-Dependent Beta Thalassemia. News release. Vertex Pharmaceuticals Incorporated. January 16, 2024. Accessed August 15, 2024. https://news.vrtx.com/news-releases/news-release-details/vertex-announces-us-fda-approval-casgevytm-exagamglogene
4. Vertex reports second quarter 2024 financial results. News release. Vertex Pharmaceuticals Incorporated. August 1, 2024. Accessed August 15, 2024. https://investors.vrtx.com/news-releases/news-release-details/vertex-reports-second-quarter-2024-financial-results
5. Center for Inherited Blood Disorders Administers Country's First Gene Therapy Infusion to Treat Hemophilia A. News release. Center for Inherited Blood Disorders. January 11, 2024. Accessed August 15, 2024. https://firstwordpharma.com/story/5817834?from=article
6. BioMarin Announces Updated Strategy for ROCTAVIAN® to Focus on U.S., Germany and Ital. News release. BioMarin Pharmaceutical Inc. August 5, 2024. Accessed August 15, 2024. https://investors.biomarin.com/news/news-details/2024/BioMarin-Announces-Updated-Strategy-for-ROCTAVIAN-to-Focus-on-U.S.-Germany-and-Italy/default.aspx
7. FDA approves first gene therapy to treat adults with hemophilia B. News release. FDA. November 22, 2022. Accessed August 15, 2024. https://www.fda.gov/news-events/press-announcements/fda-approves-first-gene-therapy-treat-adults-hemophilia-b

bluebird bio has reported 23 total cell collections for SCD and TDT gene therapies lovo-cel and beti-cel and Vertex Pharmaceuticals has reported approximately 20 cell collections for SCD/TDT gene therapy exa-cel.

Topic

Uptake of Nononcology Gene Therapy Remains Slow in Hematology

Sarepta Therapeutics’ delandistrogene moxeparvovec-rokl (marketed as Elevidys), an adeno-associated virus (AAV) vector-based gene therapy for patients with Duchenne muscular dystrophy (DMD), was originally 

 under an accelerated approval pathway for a limited indication on June 22, 2023: ambulatory patients aged 4 to 5 years with DMD and a confirmed mutation in the DMD gene, excluding patients with any deletion in exon 8 and/or exon 9.

 Later, on June 20, 2024, the FDA approved the gene therapy for use in a broader indication: ambulatory patients (via traditional approval) and nonambulatory patients (via accelerated approval) with a confirmed mutation in the 

 gene who are 4 years of age or older and who do not have any deletion in exon 8 or exon 9 in the gene.

Elevidys is the most recent of several new options to come into the DMD paradigm within recent years, joining other treatments option such as exon-skipping therapy. Although these treatments are disease-modifying and have the potential for a transformative impact, none of them are curative, and they each carry their own risks. Furthermore, the uptake of Elevidys by the community is just beginning.

Nevertheless, in observance of World Duchenne Awareness Day, held annually on September 7, 

 has reached out to several experts to learn about the real-world experience of gene therapy’s use in DMD thus far. Insights from experts interviewed by 

 spoke to John Brandsema, MD, a pediatric neurologist in the Division of Neurology at Children’s Hospital of Philadelphia, about how the FDA’s approval of Elevidys changed the treatment landscape for DMD, how the experience of integrating the gene therapy into clinical practice has gone so far, and how doctors should help patients and families choose the right treatment option for DMD going forward. Brandsema explained how Elevidys fits into the rapidly expanding landscape of care for the disease, noting that the therapy offers patients the opportunity to get back a functional, although truncated, version of the gene that is mutated and nonfunctional in their own genome. He then went over the known safety risks of the therapy, as well as potential risks that are not yet confirmed. He emphasized the need for more long-term data, especially for older patients, as many patients treated thus far have been on the younger end of the spectrum.

Brandsema also discussed issues of access to Elevidys and other treatment options for DMD, noting that not all of the options are universally covered by patients' insurance and that some of the precautions and infrastructure that need to be in place to treat patients with gene therapy slow down the rate at which new patients can receive Elevidys. He also discussed the importance of age of treatment, noting that early treatment may help prevent further neurodegenerative effects of the disease, and as such comes with a sense of urgency, but that healthcare providers want to be able to provide the product to all patients and families who are interested, both those who are younger and older. As such, making decisions can be a balancing act. Brandsema also touched on the potential to combine multiple treatment options, such as gene therapy and exon-skipping therapy, for subsequent treatment of the same patients. He noted, however, that this may prove challenging from the perspective of insurance coverage and from the perspective of monitoring for adverse events (AEs), as the ability to attribute AEs to one treatment or the other may be confounded.

Brandsema discussed the gene therapy for DMD.

Elevidys: Balancing Risks and Rewards

Making Decisions in the Face of Rapidly Expanding Treatment Options

In addition to the new therapeutic options for DMD that have been approved over the past 5 or so years, a large number of clinical trials for novel DMD therapeutics, such as gene-editing therapies, are currently ongoing. As such, patients and their families may not only choose between FDA-approved options, but also between enrolling in one of several active clinical trials, as well.

 spoke to Barry J. Byrne, MD, PhD, the chief medical advisor of Muscular Dystrophy Association (MDA) and a physician-scientist at the University of Florida, to get his perspective on both the real-world experience with Elevidys’ integration into clinical practice and his view on treatment decision-making in the aforementioned world of new commercial and investigational treatment options. Byrne emphasized that this is a difficult time for decision-making with the number of options available and that doctors will need to play an active role in helping patients and their families to pick the treatment path that is right for them. He discussed several promising investigational treatments that are being evaluated by various companies and institutions right now and pointed out that the potential for combination treatments may expand the breadth of decision-making even further. Byrne also noted the importance of work being done by several muscular dystrophy advocacy groups, such as the 

, to distribute relevant educational information and materials to the patient community.

Byrne discussed the gene therapy for DMD.

Making Decisions for DMD Treatment

Limitations of Current Therapies and the Promise of Gene Therapy to Address Unmet Needs

Besides gene therapy, exon-skipping therapy is one of the primary approaches for treating DMD, with 4 FDA-approved drugs available; although, they only cover about 30% of patients because of specific genetic mutation requirements, according to a conversation 

 had with Emma Ciafaloni, MD, who serves as a professor of neurology and pediatrics at University of Rochester Medical Center.

In a news network interview, Ciafaloni told 

 that these treatments require weekly IV infusions, but advancements in next-generation exon-skipping drugs may lead to more effective therapies with less frequent dosing. In addition, Ciafaloni said that significant progress is being made in gene replacement therapies, where mini or microdystrophin genes are engineered to be small enough for delivery via AAV vectors, potentially offering a one-time IV infusion solution for broader patient populations.

Focusing on gene therapy and exon skipping medications, an expert on Duchenne muscular dystrophy discusses current and emerging treatment options.

Gene Therapy for Treatment of Duchenne Muscular Dystrophy

Efforts in the Duchenne Community to Educate Patients on Gene Therapy

, Michael Kelly, PhD, the chief scientific officer at CureDuchenne, and Deborah Miller, the CEO and founder of CureDuchenne, discussed a webinar focused on a new treatment for DMD, hosted by the organization in English and Spanish for the Duchenne community after the FDA approved the expansion label for Elevidys.

 The duo talked about how Diana Castro, MD, a neuromuscular specialist at the Neurology & Neuromuscular Care Center, shared her insights about its mechanism and the practical realities of treatment administration in the webinar. The webinar discussion emphasized the importance of educating both clinicians and families about the drug’s benefits and risks. In the discussion, Kelly highlighted the important role of physicians' experiences and the ongoing efforts of pharmaceutical companies to streamline drug access for patients.

During the conversation, Miller expressed her initial surprise and optimism about the expanded approval of Sarepta’s gene therapy, emphasizing the essential need for more treatment options in the DMD community. Both Kelly and Miller stressed the importance of patient choice in treatment, especially in a disease as progressive as DMD. Although they celebrated the progress made, they acknowledged the limitations of current gene therapy and shared their organizations' commitment to furthering research, including exploring new approaches like nonviral gene therapies and exon-skipping technologies.

The chief executive officer and the chief scientific officer at CureDuchenne talked about a recent webinar that discussed the broad FDA approval of a gene therapy for Duchenne muscular dystrophy, highlighting patient choice and the ongoing efforts to improve treatments.

Broad FDA Approval of Gene Therapy Expands Treatment Choices for Duchenne Muscular Dystrophy: Debra Miller & Michael Kelly, PhD

On the whole, it is an exciting time for the field of neuromuscular disease, as more and more disease-modifying treatments for devastating disorders like DMD become available to patients, and an even greater number are in or entering clinical trials. Although this is reason for optimism, the lack of an approved therapy that is curative and the different risks associated with the different treatment modalities, renders the decision-making process for treatment paths more complicated than ever for treating physicians, patients, and their families. 

As an addendum to the interviews with Brandsema and Byrne, 

 asked each whether they had any messages to share with the clinician and patient communities for World Duchenne Awareness Day this year.

“I would first like to wish everyone in the DMD community a very happy World Duchenne Awareness Day,” Brandsema said. “I think that we’ve come a long way as a community in terms of having new hope for a different experience of this disease based on both our strides with genetically-targeted as well as muscle-targeted therapies, but we still have a lot of work to do together as a community to have the best possible life lived with DMD.”

“World Duchenne Awareness Day is really an opportunity for us as a provider community to reflect on all the new options there are for treatment,” Byrne said. “I think it will be fun to celebrate those developments—and the treatment landscape keeps improving. I think the provider community certainly welcomes that as do patients because it will ultimately really improve the lives of all those living with DMD and Becker muscular dystrophy, so we’re excited to contribute to that celebration.”

REFERENCES
1. Sarepta Therapeutics Announces FDA Approval of ELEVIDYS, the First Gene Therapy to Treat Duchenne Muscular Dystrophy. News release. Sarepta Therapeutics. June 22, 2023. Accessed September 6, 2024. https://investorrelations.sarepta.com/news-releases/news-release-details/sarepta-therapeutics-announces-fda-approval-elevidys-first-gene
2. Sarepta Therapeutics Announces Expanded US FDA Approval of ELEVIDYS to Duchenne Muscular Dystrophy Patients Ages 4 and Above. News release. Sarepta Therapeutics, Inc. June 20, 2024. Accessed September 6, 2024. https://investorrelations.sarepta.com/news-releases/news-release-details/sarepta-therapeutics-announces-us-fda-acceptance-efficacy?_ga=2.242068545.254033713.1708093077-1826905377.1708093076
3. Global Nonprofit CureDuchenne to Host Informational Webinars Following FDA Label Expansion of Sarepta Therapeutics’ Gene Therapy, ELEVIDYS. News Release. CureDuchenne. Published June 21, 2024. Accessed September 6, 2024. https://cureduchenne.org/general/global-nonprofit-cureduchenne-to-host-informational-webinars-following-fda-label-expansion-of-sarepta-therapeutics-gene-therapy-elevidys/

In honor of World Duchenne Awareness Day, held September 7, several experts have provided their insights on the real-world experience of gene therapy’s use in Duchenne muscular dystrophy.

Real-World Experience With Duchenne Muscular Dystrophy Gene Therapy

Ractigen Therapeutics has received orphan drug designation (ODD) from the FDA for RAG-18, its investigational small activating RNA (saRNA) that is currently in preclinical development for the treatment of cases of Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) caused by any mutation in the 

Notably, the therapy previously received a rare pediatric disease designation from the FDA in July 2024. According to Ractigen, it is the first saRNA therapy to receive both designations from the agency.

RAG-18 is intended to function through targeted activation of the 

 gene in muscle cells, leading to increased production of utrophin, the protein encoded by UTRN. Because utrophin is structurally and functionally similar to dystrophin, the protein that is deficient in patients with DMD, it is expected that its upregulation will provide clinical benefit. The activation takes place through RNA activation (RNAa), Ractigen’s platform technology designed to enable increased expression of endogenous genes through the targeting of gene regulatory domains with saRNAs. RAG-18 was administered via subcutaneous injection in preclinical research with the use of the company’s lipid-conjugated oligonucleotide (LiCO) technology.

“Receiving FDA ODD marks a pivotal achievement for RAG-18,” Long-Cheng Li, MD, the founder and chief executive officer of Ractigen Therapeutics, said in a statement.

 “Combined with the recent rare pediatric disease designation, it reflects the groundbreaking work we’re doing with RNAa and reinforces our commitment to making a real difference in the lives of those affected by rare diseases. This recognition fuels our determination to push forward with RAG-18’s development, aiming to bring innovative and life-changing treatments to DMD and BMD patients around the world.”

Ractigen presented cell line and mouse model data related to RAG-18 at the 2023 meeting of the Oligonucleotide Therapeutics Society (OTS), held October 22 to 25, in Barcelona, Spain.

 In skeletal muscle-derived cell lines, it was found that promoter-targeted saRNAs induced the expression of human utrophin mRNA and protein. Furthermore, lead saRNA candidates were evaluated for efficacy in a mouse model of DMD with knock-in of the human UTRN promoter (hUTRNp KI/KI x MDX mice), and the induction ability was validated in this model.

“In summary, our work provides initial evidence that saRNAs could be delivered to skeletal muscles and heart to activate endogenous utrophin gene,” first author Wei-Hsiang Lin and colleagues wrote in the poster presented at the conference.

 “Treatment of MDX mice bearing human UTRN promoter with a lead saRNA ameliorated muscle damage. Our approach could represent a novel and translatable therapeutic strategy for DMD and BMD caused by any mutation of the DMD gene.”

Ractigen’s pipeline includes a number of other saRNA therapies for various indications.

 The furthest along in development is RAG-01, which has entered a phase 1 clinical trial for the treatment of non-muscle invasive bladder cancer (NMIBC). It is intended to activate the expression of a relevant tumor suppressor gene that is usually silenced in bladder cancer cells.

“FDA investigational new drug (IND) application approval for RAG-01 is a major achievement for Ractigen and a significant advancement for saRNA technology worldwide,” Li said in April 2024, when the therapy received IND clearance in the United States.

 “This first-in-class saRNA therapy harnesses the power of RNAa to target the 

 gene, offering a promising new option for patients with limited treatment choices. This approval validates the potential of RAG-01 as a leading saRNA therapy and strengthens our position as innovators in RNA-based treatments.”

REFERENCES
1. Ractigen Therapeutics announces U.S. FDA orphan drug designation (ODD) granted to RAG-18 for the treatment of Duchenne muscular dystrophy and Becker muscular dystrophy. News release. August 22, 2024. Accessed September 5, 2024. https://www.ractigen.com/ractigen-therapeutics-announces-u-s-fda-orphan-drug-designation-odd-granted-to-rag-18-for-the-treatment-of-duchenne-muscular-dystrophy-and-becker-muscular-dystrophy/
2. Lin WH, Pan XJ, Duan CL, Liu KS, Kang M, Li LC. Therapeutic development of saRNA for Duchenne muscular dystrophy by targeted activation of utrophin. Presented at: 2023 meeting of the Oligonucleotide Therapeutics Society (OTS), held October 22 to 25, in Barcelona, Spain. Poster #P134
3. Ractigen Therapeutics. Our Pipeline. Website. Accessed September 5, 2024. https://www.ractigen.com/pipeline/
4. Ractigen Therapeutics announces FDA approval for RAG-01, a first-in-class saRNA therapy for BCG-unresponsive NMIBC. News release. April 26, 2024. Accessed September 5, 2024. https://www.ractigen.com/ractigen-therapeutics-announces-fda-approval-for-rag-01-a-first-in-class-sarna-therapy-for-bcg-unresponsive-nmibc/

Notably, the therapy previously received rare pediatric disease designation from the FDA in July 2024.

Ractigen Garners Orphan Drug Designation for Muscular Dystrophy saRNA Therapy RAG-18

This is the second part of an interview with David Dimmock, MBBS. For the first part, 

Creyon Bio has been treating a child with a de novo heterozygous pathogenic variant causing a missense change in TNPO2 with an antisense oligonucleotide (ASO) therapeutic created using the company's AI discovery platform. Creyon presented data from this proof-of-concept case study at 

the American Society of Gene & Cell Therapy (ASGCT) 27th Annual Meeting

, held May 7 to 10, 2024, in Baltimore, MD.

sat down with David Dimmock, MBBS, chief medical officer at Creyon, to get his insight on the findings from the case study so far. Dimmock went over the increasing doses of the ASO that were administered to the child and the changes reported after each dose, emphasizing that the findings so far seem to indicate that more frequent redosing would be beneficial.

 Can you go over the data from the case study?

 As with every new therapy, there are ways that we need to convince ourselves and we need to convince the regulators and the family that the ASO is safe enough. It's a real challenge because you've got a child who's getting worse in front of your eyes and you're sitting waiting for good lab practice animal studies. You're waiting for all of the drug manufacturers to sign off on all of the lots demonstrating the drug is safe. So unfortunately, from the point of actually having a drug made to being ready to dose the patient took about 6 months. After the first 5 mg dose, really nothing happened. That wasn't a surprise, we thought it was going to be too small a dose, but we wanted to make sure we started at the low dose and made our way up because we didn't want to give too much. So we then gave 10 mg, 20 mg, and then 40 mg, which was our target dose. Within a few days of giving the 10 mg dose, the parents called us saying their child was doing better. I think all of us are very concerned about a placebo effect. We hadn't seen that after the 5 milligram dose, but [we had to find out whether] there is robustness and durability to this? 

Once we gave the 20 mg dose, the parents reported that for the first time really in about a year, the child was actually rolling over. The child had pretty significant cross eye, which we thought might be part of the disease. One of the other really surprising things was, after we gave the 40 mg dose of the ASO, the child's cross eye actually corrected itself, and the eyes turned back to being at a point where they were both looking. We saw a dramatic reduction in the how often the baby was seizing. This child was having such bad seizures on the day before we gave the first dose that the doctor that's treating this child, Dr. Nicole Coufal, who really is the person who's made this all happen, had actually breathed for the child for a little bit in clinic, because the seizure was so bad, the child had stopped breathing for long enough that they actually had to intervene. 

So we went from the point where the cyanotic seizures were happening multiple times a day, to being at a point where, after the 20 mg dose, for a couple of weeks, the child had no seizures. All the more remarkably, over Thanksgiving, the child had a viral infection that actually was bad enough to put them in the ICU. Every time prior, when the child got a minor infection, as with most kids with seizures, the seizures got dramatically worse. Instead at this point, the child was in the ICU, sick with a respiratory infection, but not having any seizures at all. 

As we've progressed, we didn't know what the half-life of the drug would be, and so there was an extent to which we just had to figure this out empirically, unfortunately, in the child. We initially planned dosing once every 3 months, or once every 90 days. What we found was that we saw a dramatic response at the first 40 mg dose, but after about 5 or 6 weeks, the child started to go backwards again and had an increase in seizures. Some of the skills that had been acquired started to get lost. We gave the next 40 mg dose and within about a week, the child was back doing all of these skills again, and then some more as well—actually we'll show the video on Friday showing the child actually being able to sit up—with some help and with some support, but nonetheless, sitting up. And I think more importantly, the parents have been really interactive with them. Again after the second dose, and after about a month and a half, the drug seemed to wear off and the child stopped interacting with parents, again. We gave the third dose in January, and we saw the same thing again, the child dramatically better... We gave the [next] dose in April of this facing out, and again, we saw the same thing: the child got dramatically better within 3 or 4 days, and actually, the video we're going to show of him sitting up was about 3 days after that dose in April.

So we're all kind of sitting nervously now as we're expecting the drug's going to wear off again in the next few weeks... We’re at the point now where we're very confident that the drug is working, because every time we give the drug, the child gets dramatically better, but unfortunately, it seems to be wearing off. So we're in the process of working out what safety data we need to persuade everybody that it would be more appropriate to dose this child more frequently.

This transcript has been edited for clarity.

Click here to view more coverage of the 2024 ASGCT Annual Meeting.

REFERENCE
Dimmock DP, Bird L, Bouck A, et al. AI Enabled ASO Design Can Lead to Rapid Initiation of Treatment for an Ultra-Rare Disorder Leading to Allele Selective Knockdown of a Toxic Protein and Consequent Clinical Improvement. Presented at: ASGCT 27th Annual Meeting, May 7-10; Baltimore, Maryland. Abstract #309

David Dimmock, MBBS, the chief medical officer at Creyon Bio, discussed findings from a patient treated for a TNP02 missense mutation.



A Promising Case Study of Ultra-Rare, AI-Guided, ASO Development

This is the third part of an interview with David Dimmock, MBBS. For the first part, 

, held May 7 to 10, 2024, in Baltimore, MD, Creyon Bio presented a case study on its use of an antisense oligonucleotide (ASO) therapeutic created using its AI discovery platform to treat a patient with an ultrarare disease indication. At the conference, 

spoke with David Dimmock, MBBS, chief medical officer at Creyon, to learn more about the company's future plans and goals.

Dimmock noted that the company will continue to seek to provide treatments for patients with very rare disease, but also seek to apply its platform to more common indications, as well. He emphasized the significance of having a platform and the importance of obtaining FDA approval for therapeutic products for very rare diseases.

 Can you discuss other potential applications for Creyon's AI discovery platform?

 The whole point of the platform is that it enables us to make drugs safely, whether that's a drug for 1 child, as in this case, or it's a drug for thousands. The platform, in and of itself, enables us to make drugs very efficiently for common diseases and for rare disease indications. We're at a point in our company where we announced last week that we're partnering with another company to treat neurodegenerative diseases—much more common indications. Similarly, we have several internal assets that we are taking through to investigational new drug application–enabling studies at this point in time. 

Would you do more very rare, single patient indications in the future?

My day job 1 week a month is that I'm a rare disease doctor. I spend a week a month watching families go through things that no family should go through. As a company, we want to tackle this long tail of rare diseases where there are very few patients. The FDA has approved a drug based on 4 patients... So, we believe it is possible, even with very small patient populations to get drugs approved. But to get drugs approved, you need to do all the appropriate studies, which means you need to walk into the studies with a drug with a very high prior probability of success. Having the platform in place enables us to walk in with very high expectations that our drug is going to be safe. We could tell in a dish whether or not the drug works, we could see if it engages with RNA. We know how it's distributed in the liver or in the brain. But our dream, our hope, is that we will be at a point where we can get drugs that are approved. Why does it matter to have a drug approved? Well, if a drug is approved, it can then be paid for. Why does that matter? Well, most patients with rare diseases are seen in hospitals where they don't have people like Dr. Nicole Coufal who can go through the rigmarole of an FDA investigator-sponsored trial. If we have the drug approved, then any doctor with a patient with this disease can prescribe it. That actually makes these rare disease drugs more generally available.

Is there anything more the company is looking forward to?

As a company, we're very excited to be at the point where we can take more drugs into the clinic for common disease indications. Obviously, as a company we can't share too many details about them without breaking confidentiality rules. But we're definitely very excited over the next 18 months to start to see more common disease drugs come into the clinic. I'm also excited we have programs working looking at upregulating a gene for more rare disease—so using a different mechanism. I think the beauty of a platform is we don't need to pick a particular gene and run after that; any gene, any target that comes up—we can make a drug for that.

Do you have any additional thoughts on this year's ASGCT conference?

I think it's always an exciting meeting to be at to see cutting edge science. I come to meetings like this sometimes just to provide hope that we will have long-term treatments for many of the patients that I see. I think obviously with another gene therapy death announced a couple of days ago, it reminds everybody why we need to do this carefully and safely. I think there is an appropriate focus on making sure that we be careful and safe.

David Dimmock, MBBS, the chief medical officer at Creyon Bio, discussed future applications for the company’s AI-guided discovery platform.



Accelerating Therapy Discovery and Approval With AI

Creyon Bio developed an antisense oligonucleotide (ASO) therapeutic that demonstrated the ability to knock down toxic Transportin-2 (TNPO2) protein in an allele-selective manner. The target of the ASO was informed using an artificial intelligence (AI) model, and it was used in a case study for a single patient with a de novo heterozygous pathogenic variant causing a missense change in the gene that codes for TNPO2.

Investigators found that the child had a dramatic reduction in seizure frequency subsequent to the second dose and regained developmental milestones that were lost and developed new skills following the third dose. Notably, these improvements regressed and were regained between and after doses. At 

, held May 7 to 10, 2024, in Baltimore, MD, 

interviewed David Dimmock, MBBS, chief medical officer at Creyon, to learn more about the approach the company used to develop this ASO.

 Can you tell us a bit about using AI for ASO design?

 A fundamental problem with drug design is that most drugs fail because they're not safe. Often that failure happens when you get to the point where you're animal testing, or unfortunately, sometimes in humans. Oligos are a relatively simple medical modality in one sense. You can target them very specifically, but about 90% to 95% of oligos are just intrinsically unsafe out of the box, and would fail animal studies. So what Creyon did is they looked at a representative sample of many oligos, put those into animals, and were able to then take those features and predict whether or not this part or this part or this part of an oligo was going to be safe or not safe. So when you walk in and you know what sequences are going to be safe or unsafe, it then allows you when you walk in to engineer an oligo in the first place that has the pieces in that are going to work; and the pieces that won't work or cause injury—you either avoid those sequences or if you're forced, as we were in this case to a specific sequence, you can actually change the way the oligo is designed, the sugar, the base, or the linker.

Can you talk a little bit about the case study and the design process for that patient?

The family that we're talking about have been very generous in allowing us to share their story. They came to us through the TNPO2 Foundation just to the point where our platform was mature enough that we were ready to have a test case to take through and see how well it worked. We were at the fortunate point where we had the platform up and running in a sort of a beta testing phase when these parents were unfortunately presented with I think what is close to a parent's worst nightmare, their child developing intractable seizures—whereas the child had been previously interacting with them, rolling over—he'd lost the ability to do those things. So the question and the hope was: Could we actually design an oligo that could get rid of this bad protein that was building up in the brain whilst leaving the good copy of that gene alone? And would that actually make a difference? The challenge with this disease is we knew the genetic changes that were causing the disease [but] at this point we didn't have any long read sequencing, so we didn't know of any other parts of the genome that were on the bad copy of the gene. So, we were forced to design the oligo to actually hit the disease-causing variant. We were in a fortunate place with the platform where we could actually walk in and we could design oligos that we had a very high confidence were gonna be safe. And actually, when we did that, we designed 96 oligos. We knew we were in hurry, we didn't want to fail. More than 80% of those—in fact, close to 90% of those oligos—were safe when we put them in mice. We actually tested all of these oligos in mice, both in their brains and systemically, looking at their liver and their kidneys. The thing that made this case particularly tricky was we had to get rid of the bad copy of the gene whilst leaving the good copy alone. So we had to make sure that the ASO that was knocking down the bad copy of the gene just hit the bad copy and didn't hit the good copy. That made the place where we could target really quite small.

David Dimmock, MBBS, the chief medical officer at Creyon Bio, discussed the development of an allele-selective ASO for a single patient with a de novo pathology.



Jacquelyn Gray

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