With ‘great promise’ for treating Huntington’s disease, four drug programs press ahead (Part II)

 

At the recent 20th Huntington’s Disease Therapeutics Conference in February, four pharmaceutical companies provided updates on their key clinical trial programs, demonstrating that they had overcome basic safety hurdles and revealing plans to have their drugs potentially approved as therapies (treatments) for delaying the progression of HD symptoms.

 

All four programs use drugs to lower the amount of harmful mutant huntingtin protein in the brain cells of patients.

 

In the first of two articles on these programs, I described the projects of PTC Therapeutics and Roche.

 

In this article, I cover the presentations made by Wave Life Sciences and uniQure.

 

These updates took place during the conference’s first session on February 25, the first day of the three-day event.

 

In a post-conference interview Robert Pacifici, Ph.D., the chief scientific officer for CHDI Foundation, Inc., the conference sponsor, told me that that there is “great promise” regarding these four programs’ potential HD therapies.

 

Attacking only the bad protein, preserving the good one

 

Jane Atkins, Ph.D., Wave’s senior vice president for portfolio strategy and program management, provided an update on the company’s groundbreaking program.

 

Like Roche’s tominersen, Wave’s WVE-003 is an antisense oligonucleotide, an artificial strand of DNA that blocks or lowers the production of the huntingtin protein.

 

However, whereas tominersen and PTC’s votoplam (a splicing modulator) reduce both the mutant and normal huntingtin protein, Wave’s drug is uniquely allele-selective: it attacks just the bad protein and allows the good one to carry out its essential actions unhampered.

 

Clinical trials for drugs usually go through three phases. If the last is successful, the drug can receive approval from the U.S. Food and Drug Administration (FDA).

 

In 2021, in small clinical trials, precursors WVE-120101 and WVE-120102 failed to reduce the bad protein. Wave then developed WVE-003, which entered a clinical trial that same year.

 

At the conference, Dr. Atkins reported that in June 2024 the Phase 1b/2a SELECT-HD study of WVE-003 produced positive results, “including the first allele-selective silencing in any disease.”

 

“A growing body of literature” supports the importance of the good huntingtin protein, she explained, as it sustains the health of brain cells.

 

Slowing the shrinking of the brain

 

In the clinical trial, the bad protein was reduced as much as 46 percent in some volunteers, exceeding the overall goal of 30 percent, Dr. Atkins said, noting that the drug was safe and well-tolerated.

 

Significantly, the study also demonstrated a slowing in the atrophy (shrinking) of the caudate, a key part of the brain dramatically affected in HD, leading to a decline in cognition, function, and movement, Dr. Atkins said. Such atrophy occurs before symptoms appear, she noted, so being able to observe this change early makes the atrophy a good measure of a drug’s effectiveness.

 

The slower shrinking “was the first time this was shown in the clinic,” Dr. Atkins said. “We were super-excited to see this.”

 

With these promising results, Wave plans to put WVE-003 into a combined Phase 2/3 clinical trial, Dr. Atkins said. The company later this year expects to seek FDA approval of the trial. Wave proposes to use caudate atrophy as a primary endpoint, that is, a main measure of WVE-003’s effectiveness.

 

Wave is also investigating WVE-003’s potential impact on somatic expansion, Dr. Atkins said. Somatic expansion is the tendency of the mutant huntingtin gene to continue expanding over time. Many scientists now believe that this process triggers HD symptoms.

 

Somatic expansion is understood as a two-step process where expansion of the gene (step 1) triggers disease (step 2) that drives HD. Wave believes that lowering the bad protein selectively (with WVE-003) is likely to address the second step.

 

As with tominersen, WVE-003 is administered via a spinal tap. Votoplam is a pill.

 

 

Dr. Jane Atkins of Wave Life Sciences displays a slide demonstrating the slowing of caudate atrophy in the WVE-003 clinical trial (photo by Gene Veritas, aka Kenneth P. Serbin).

 

uniQure drug slows disease progression in trial

 

David Margolin, M.D., Ph.D., uniQure’s vice president for clinical development, gave a presentation on the latest developments regarding AMT-130, the firm’s gene therapy drug that reduces the levels of both the good and bad huntingtin protein.

 

In the uniQure clinical trial, a neurosurgeon injects AMT-130 directly into the brains of the volunteers under the guidance of an MRI. As a gene therapy, AMT-130 requires just this one application. (Watch the uniQure video about how AMT-130 is administered here).

 

This small, long-term uniQure Phase 1/2 trial began in 2020. As of April, the number of participants had reached 45, including people from the U.S. and Europe.

 

An interim analysis in mid-2024 showed that “AMT-130 high dose … strongly and significantly reduced disease progression,” Dr. Margolin pointed out. Another analysis found “substantial reduction in risk of clinically meaningful worsening,” he added.

 

As patients continue to go through the trial and beyond, with follow-up, “with every data cut we see… a promising treatment effect becoming more and more evident,” Dr. Margolin said.

 

 

Dr. David Margolin of uniQure presents data illustrating the slowing of HD disease progression in the AMT-130 clinical trial (photo by Gene Veritas).

 

Hoping to accelerate approval

 

The positive results have led uniQure to seek acceleration of FDA approval for AMT-130.

 

Because of HD’s status as a rare disease, in 2017 uniQure received the financially beneficial orphan drug designation from the FDA for AMT-130. In 2019, FDA granted AMT-130 fast track status to further facilitate development of the drug and expedite review.

 

As explained by Dr. Margolin at the conference, in 2024 the FDA defined AMT-130 as a regenerative medicine advanced therapy (RMAT).

 

This category includes life-threatening diseases such as HD. Dr. Margolin said it is applicable to new kinds of drugs such as gene therapy, cell therapy, and tissue-engineered products, and it further accelerates FDA review.

 

In achieving this designation, uniQure presented to the FDA the data from the Phase 1/2 trial, and the FDA agreed that this data can serve as the primary basis for a drug application, Dr. Margolin said.

 

Dr. Margolin indicated that this determination means that uniQure will not need to put AMT-130 into a Phase 3 trial.

 

“An additional investigational study will not be required,” he emphasized. “That accelerates by several years the timeframe in which AMT-130 might become available to a wider U.S. cohort of patients.”

 

Swaying the FDA to be more flexible

 

Because of the lack of therapies that modify the course of this rare and devastating disease, the uniQure project and the company’s dialogue with the FDA have indicated the willingness of the agency to allow flexibility in clinical trial programs and a faster timeline.

 

Dr. Margolin’s talk title included the phrase “alignment on a US Regulatory Path Via RMAT.” Alignment with the FDA could lead to an “accelerated approval” for AMT-130, he observed.

 

Dr. Margolin asserted that uniQure’s dialogue with the FDA “has meaningfully advanced HD regulatory science.”

 

In response to a question from Dr. Pacifici about the negotiations with the FDA, Dr. Margolin stated that uniQure hopes that the lack of disease-modifying therapy is “swaying FDA to be more liberal than they have been in the past.”

 

Dr. Pacifici asked what additional studies uniQure will conduct if it secures the accelerated approval, which would still be only conditional.

 

Dr. Margolin replied that uniQure will discuss that matter with the FDA.“Importantly, even an accelerated approval means the drug will be available to patients,” Dr. Margolin stressed. “It does constrain promotional materials in certain ways, but would have no relevant impact on its potential availability and accessibility to U.S. patients.”

 

A Breakthrough Therapy designation

 

AMT-130 gained RMAT designation because it is a gene therapy. Since the conference, the AMT-130 program has made yet further progress.

 

On April 17, uniQure announced that the FDA granted Breakthrough Therapy designation to AMT-130.

 

“Receiving Breakthrough Therapy designation underscores both the urgent need for effective treatments for Huntington’s disease and the encouraging interim data demonstrating that AMT-130 has the potential to slow disease progression,” said Walid Abi-Saab, M.D., chief medical officer of uniQure, in a press release. “We look forward to working closely with the agency to bring AMT-130 to the Huntington’s disease patient community as quickly as possible.”

 

As explained in the press release, Breakthrough Therapy designation for AMT-130 means that the drug “may demonstrate substantial improvement over available therapy on a clinically significant endpoint(s).” 

 

The firm expects to provide a further FDA update this quarter. In the third quarter, it aims to present data on AMT-130 to support its potential drug application submission.

With ‘great promise’ for treating Huntington’s disease, four drug programs press ahead (Part I)

 

At the recent 20th Huntington’s Disease Therapeutics Conference, four companies provided updates on their key clinical trial programs, demonstrating that they had overcome basic safety hurdles and revealing plans to have their drugs potentially approved as therapies (treatments) for delaying the progression of HD symptoms.

 

PTC Therapeutics, Roche, Wave Life Sciences, and uniQure made 15-minute presentations. This clinical trials update took place during the first session on February 25, the first day of the three-day event.

 

Sponsored by the nonprofit CHDI Foundation, Inc., the largest private funder of HD research, the conference took place in Palm Springs, CA.

 

Possible impact

 

All four programs use drugs to lower the amount of harmful mutant huntingtin protein in the brain cells of patients. Blocking the bad protein could help prevent the death of brain cells, a major driver of HD.

 

In a post-conference interview with me, CHDI Chief Scientific Officer Robert Pacifici, Ph.D., said that the companies’ plans to move their programs towards drug approval is “great news.”

 

“All of them expressed their commitment to moving forward with their interventions, and that’s not trivial,” Dr. Pacifici said. “That means a lot of time, a lot of money invested on their part. They wouldn’t be doing it if they didn’t think there was great promise there.”

 

Each firm has overcome the basic safety hurdles necessary for moving to a Phase 3 clinical trial, the final step before the U.S. Food and Drug Administration (FDA) approves a drug, Dr. Pacifici added.

 

This article, the first of two, focuses on trials from PTC and Wave. Part II will examine the Wave and uniQure updates.

 

Votoplam, a potential pill for HD

 

With 60 companies represented at the conference, CHDI selected those “that had something new to say” in terms of clinical development, Dr. Pacifici told the attendees.

 

Amy-Lee Bredlau, M.D., PTC’s senior medical director, began her talk on the company’s huntingtin-lowering drug by noting progress: the compound, PTC518, is now called votoplam, a nonproprietary drug name assigned by PTC’s new, larger partner on the project, the international pharmaceutical firm Novartis.

 

“I think this is a really great collaboration,” Dr. Bredlau said.

 

As Dr. Bredlau explained, votoplam is a huntingtin splicing modulator, reducing the production of both the mutant and normal huntingtin proteins.

 

In contrast with riskier delivery methods, some presented in the session, votoplam is a pill. That makes it easy for patients to take the drug.

 

CHDI and PTC started the search for a huntingtin-lowering pill with a joint project initiated in 2018.

 

A delay in HD progression

 

PTC ran a successful Phase 1 clinical trial of votoplam in 2020 and 2021, providing initial evidence of safety and the lowering of the huntingtin protein.

 

At the conference, in an interim analysis, Dr. Bredlau presented data from the first 32 of the 156 volunteers enrolled in PIVOT-HD, PTC’s one-year global Phase 2 trial, which has verified the safety and tolerability of the substance. The first group of participants in PIVOT-HD began in 2022.

 

PIVOT-HD demonstrated that, by the third month, votoplam enters trial volunteers’ brains and lowers the huntingtin protein, she said. At month 12, the lowering was sustained. The trial also showed no spikes in neurofilament light chain (Nfl), a protein whose presence indicates degeneration of brain cells in diseases like HD. Scientists hope that lowering huntingtin will limit Nfl.

 

Significantly, Dr. Bredlau observed that these volunteers had a delay in the progression of HD symptoms, as indicated by several key clinical measures.

 

She said PTC is “very excited” about those trends, which “look very promising,” adding that “we’re really hopeful that we’ll see a strengthening of the signal at the end of the 12-month study,” when results from the remaining volunteers will be studied.

 

PTC will release full results of PIVOT-HD in this (second) quarter of 2025, said Dr. Bredlau, adding that the firm hopes that the results secure permission for a Phase 3 trial, to be run by Novartis.

 

Dr. Amy-Lee Bredlau of PTC Therapeutics presents data from the PIVOT-HD clinical trial demonstrating trends of a delay in progression of Huntington's disease symptoms (photo by Gene Veritas, aka Kenneth P. Serbin).

 

GENERATION HD2 fully in progress

 

Peter McColgan, M.D, Ph.D., global development leader for Roche, updated the pharmaceutical giant’s HD program. He focused on the Phase 2 trial of the huntingtin-lowering drug tominersen.

 

Tominersen is an antisense oligonucleotide – a “laser-guided missile” against HD – originally developed by Ionis Pharmaceuticals, Inc. Like votoplam, tominersen lowers both the normal and mutant huntingtin protein.

 

After Roche’s unsuccessful trial of tominersen in 2021, the company redesigned a less ambitious and more focused trial of the drug in people less affected by the disease. Called GENERATION HD2, it started in early 2023.

 

Dr. McColgan reported that GENERATION HD2, by January, had fully recruited its target of 301 volunteers at 70 sites in 15 countries.

 

“This is a massive achievement,” he said.

 

The trial will assess tominersen’s safety, the use of biomarkers (signs of a disease and a medication’s efficacy), and the drug’s effectiveness.

 

Tominersen is not a pill. It is administered via a spinal tap.

 

Roche aims to complete the trial by the end of 2026.

 

Dr. Peter McColgan of Roche with a slide showing the global recruitment for the GENERATION HD2 clinical trial (photo by Gene Veritas)

 

Roche’s multiple approaches

 

Dr. McColgan also described how Roche has expanded its focus to include other possible HD treatments and related research.

 

“We believe the fastest way to get treatments to patients is to pursue multiple programs in parallel,” Dr. McColgan said.

 

In collaboration with its colleagues at Spark Therapeutics – acquired by Roche in 2019 – Roche scientists are exploring other potential molecules for targeting HD. Spark specializes in gene therapies.

 

HD researchers continue to weigh the approach of drugs such as votoplam and tominersen, which lower both the mutant and normal huntingtin protein, versus those that attack only the mutant. The latter types are known as allele-selective. They leave the normal protein to carry out its essential actions unhampered.

 

Dr. McColgan said that Roche and Ionis are investigating an allele-selective antisense oligonucleotide.

 

Roche is also participating in the HD Regulatory Science Consortium. Using data from the original tominersen trial and other patient data, this collaboration seeks to improve the measurement of clinical trial volunteers’ performance in clinical trials, said Dr. McColgan.

 

Roche is also collaborating with CHDI to improve the measurement of Nfl (neurofilament light chain) as a key biomarker.

 

“Nfl increases across the stages of HD,” Dr. McColgan observed.

 

The latest news on tominersen

 

All clinical trials are regularly checked by an independent data monitoring committee.

 

Volunteers in the tominersen trial not on placebo have received either 60mg or 100mg of the drug.

 

On April 17 Roche issued a letter to the HD community stating that the committee overseeing the tominersen trial has found “no concerns … regarding participant safety or signs of symptom worsening with either tominersen dose.”

 

In addition, the letter said, “the 100mg dose was found to be more likely than the 60mg dose to result in clinical benefit. Therefore for the remainder of the study only the 100mg dose will be tested against placebo, and the 60mg dose will be discontinued.” Those receiving 60mg will now get 100mg.

 

“We are incredibly grateful to the 301 participants and their companions enrolled in GENERATION HD2,” the letter stated. “Each study visit contributes to collecting data that helps the entire HD research community learn more about tominersen, Huntingtin-lowering strategies, and the further understanding of HD.”

 

In Part II of this article I will report on Wave’s and uniQure’s clinical trial updates

 

(Disclosure: I hold a symbolic amount of Ionis shares.)

After abrupt shutdown of Triplet Therapeutics, Huntington’s disease community regroups in the fight for therapies

 

Triplet Therapeutics, Inc., a Cambridge, MA-based start-up that aimed to transform the treatment of Huntington’s disease and related disorders, has shut down, citing a lack of new investment partners and the discovery that its proposed HD drug caused adverse effects in animal tests.

 

On October 11, Triplet CEO Nessan Bermingham announced the company’s closure on his LinkedIn page. The abrupt closure was another piece of tough news regarding potential therapies for HD.

 

In March 2021, Roche and Wave reported negative trial results for drugs aimed at reducing the toxic mutant huntingtin protein in patients’ brains. These drugs are antisense oligonucleotides (ASO), a synthetic modified single strand of DNA that can alter production of certain proteins.

 

Triplet’s strategy

 

Triplet had designed its own ASO, but with a different strategy: to stop the deleterious expansion of the mutant huntingtin gene (click here to read more). Known as somatic expansion, this process drives the disease and can hasten the onset of symptoms. By slowing this expansion, Triplet had hoped that its drug would head off the disease early.

 

Triplet scientists and others have viewed this approach as a more effective alternative to the “huntingtin lowering” strategy devised by Wave, Roche, and others.

 

Capitalizing on recent groundbreaking HD genetics research, Triplet, founded in late 2018, developed the only clinical trial program to slow or stop somatic expansion in HD. Triplet also had hoped to develop treatments for others among the 50 rare conditions with somatic expansion, which, like HD, are called repeat expansion disorders.

 

 

Brian Bettencourt, Ph.D., Triplet's former senior vice president for research, explains a slide illustrating the firm's pathway to a potential HD drug at the 15th Annual HD Therapeutics Conference, 2020 (photo by Gene Veritas, aka Kenneth P. Serbin).

 

“It is with great sadness we announce the closure of Triplet Therapeutics,” Bermingham wrote on LinkedIn.

 

The “underlying science of targeting repeat expansion disorders” remains “a viable approach from our vantage point,” Bermingham wrote. However, crucially, in animal studies, the data from Triplet’s HD drug “reflected prior experiences” with ASO toxicity in the central nervous system – a reference to the Roche and Wave results.

 

Specifically, the ASO showed signs of harming neurons (brain cells). “As a therapeutic modality, given Roche’s data, our data, lack of efficacy from Wave products, our belief is that neurons may be particularly sensitive to antisense oligonucleotides,” Bermingham told STAT.

 

Triplet secured $59 million in initial financing and investment. After the bad news in 2021 from Roche and Wave, Triplet struggled to raise the money needed for its planned next step: an early phase clinical trial of its ASO. “The clinical data really put a chill on the overall interest or risk perceived within Huntington’s disease,” Bermingham noted.

 

SHIELD HD continues to provide key data

 

To provide data about the disease for the clinical trial it was planning, Triplet has run a separate, two-year study, without a drug, of approximately 70 presymptomatic and early-disease-stage carriers of the HD mutation. Called SHIELD HD, the study involves cognitive testing, brain MRI scans, blood tests, and examination of cerebrospinal fluid drawn from spinal taps (click here to read more). The sites are Canada, France, Germany, the United Kingdom, and the U.S.

 

In March, Triplet scientists presented a preliminary analysis of this data at the 17th Annual HD Therapeutics Conference, sponsored by CHDI Foundation, Inc., the virtual nonprofit biotech focused exclusively on developing HD therapies. CHDI is the largest private funder of HD research.

 

SHIELD HD may end in the next few months. In Bermingham’s announcement about the closure of Triplet, he said that CHDI, “a great partner and patient advocate,” stepped in to help SHIELD HD sites complete their work.

 

Triplet’s representatives are now seeking potential partners to continue the company’s research, including a new plan for a clinical trial.

 

Assessing risk

 

In an online interview with me on October 21, Irina Antonijevic, M.D., Ph.D., the former chief medical officer of Triplet, explained that discovering toxicity of the ASO in the animal studies surprised the firm’s researchers. However, she emphasized that the toxicity was “minimal” at therapeutic dose levels, with the animals not suffering any functional loss.

 

As noted publicly, Triplet had also developed several, more potent backup ASOs, Dr. Antonijevic said. The more potent the drug, the smaller the dose needed, therefore reducing the chance of toxicity or an adverse effect, she added.

 

Nevertheless, in a more risk-averse investment climate, Triplet could not find the necessary partners to carry on its clinical trial program with the added concern about the toxicity, Dr. Antonijevic observed.

 

“I think that they are just sort of very different risks,” she said. “Somebody takes maybe a risk to say, ‘Maybe this drug has a risk, but I have a disease, and I know what this disease will do to me.’”

 

For a drug company, the risk involves “investing millions” and waiting years to see if there is a return on investment, she said.

 

Tweaking drug safety, efficacy, and delivery

 

Triplet’s experience revealed how the field of HD drug development needs to tweak the safety, efficacy, and delivery of ASOs into the brain. Despite the challenges, a number of other firms and many researchers believe ASOs merit more study and clinical trials.

 

Roche has developed a revised clinical trial plan, including lower and thus potentially less toxic doses of its ASO. It will start a second trial of that ASO in early 2023.

 

Wave, building on its failed 2021 early stage trials of two ASOs, put a third drug into another small, early phase trial. Unlike the previous drugs, this Wave ASO successfully reduced the mutant huntingtin protein. Also, for the first time, it did this without lowering the level of the healthy protein – something that occurs with the Roche drug.

 

“This is, as far as we know, the first time anyone has ever selectively lowered only one copy [of a total of two] of a protein inside of a human body,” the HD science site HDBuzz commented on Sept. 30.

 

The method of delivery is important for all drugs, especially for ones introduced into the brain. The Roche and Wave trials use spinal taps (intrathecal injections). Triplet had projected using an

injection via a small reservoir implanted on the top of the brain. The firm uniQure is injecting its drug using brain operations.

 

Developing a pill

 

Drug developers point out that the most convenient HD drug would be a pill – taken orally, at home, and without medical assistance. These drugs are known as small molecules.

 

Several firms have embarked on small molecule clinical trial programs for HD.

 

An important trial of one of these small molecule drugs, a huntingtin-lowering pill developed by Novartis, was halted in August for safety reasons. Some of the trial volunteers on the drug developed problems with their nerves, known as peripheral neuropathy.

 

FDA requests more data from PTC

 

On October 18, another firm enrolling people in a clinical trial for a small molecule, PTC Therapeutics, Inc., was asked by the U.S. Food and Drug Administration (FDA), to provide further information before allowing a clinical trial of its HD drug, PTC518. PTC announced that enrollment is ongoing for the planned 12-month Phase 2 trial in several European countries and Australia.

 

Both branaplam and PTC518 are so-called splicing molecules.

 

“PTC pioneered the development of splicing molecules and we have learned about the essential elements to successfully develop these molecules,” Jeanine Clemente, the senior director of corporate communications at PTC, wrote me in an October 20 e-mail in response to my questions about the FDA decision. “We cannot comment on the FDA’s thoughts regarding branaplam or splicing molecules, in general.”

 

However, Clemente pointed out that PTC518 is highly specific and selective for the huntington gene.” She added that, in many important ways, “PTC518 is different than branaplam.”

 

HDBuzz also noted that PTC518 “may have more ideal drug properties, compared to branaplam.”

 

The FDA has asked PTC for additional data to support the dose levels and duration proposed in the trial, Clemente wrote.

 

Clemente added that PTC enrolled its trial entirely with patients outside of the U.S., including approvals to conduct the study at all proposed dose levels. “There have been no treatment-associated adverse events reported to date,” she stated. “We will continue to work with the FDA to potentially enable enrollment of U.S. patients in the trial.”

 

Keeping perspective in a difficult fight

 

Triplet will host a podcast later this year to discuss the “birth, life and death” of the firm, CEO Bermingham stated in his announcement of the closure.

 

The HD community must keep the Triplet shutdown – and all news regarding the ups and downs of the search for HD therapies – in perspective, noted Martha Nance, M.D., the director of the Huntington’s Disease Society of America Center of Excellence at Hennepin County Medical Center in Minneapolis.

 

“We would not do research if we already knew all the answers,” Dr. Nance wrote me in an October 18 e-mail. “HD patients and families have bravely faced their difficult disease for generations, and the doctors and scientists are doing their best, along with patients and families, to find a brighter path.”

 

As an asymptomatic HD gene expansion carrier who has not yet participated in a clinical trial, I had high hopes for the Triplet program, with its focus on attacking the disease in the early stages. I was deeply saddened to hear that the firm closed. I also felt in the gut once again the hard reality of marshalling resources – including financial support – for combating rare diseases.

 

Companies like Triplet are venture capital-funded businesses pursuing high-risk, high-reward endeavors, and many such endeavors fail. So we are fortunate to have a nonprofit like CHDI as a backstop.

 

Dr. Nance’s wisdom reminded me of the need to join with my fellow HD and rare disease advocates to regroup in the fight for therapies.

 

“Finding a solution to brain cell death in HD is not easy,” she observed. “And as we edge closer to an answer, each failure seems more dramatic. It would be nice if the answer would just reveal itself, if the answer to HD was simple and easy, but we will not let the setbacks of the last two years prevent us from moving forward.”

After a difficult year for the Huntington’s disease cause, CHDI chief scientist feels ‘reinvigorated’ and ‘optimistic’ about quest for therapies

 

Having faced negative results in two key clinical trials a year ago while battling the coronavirus pandemic, the Huntington’s disease community has renewed the quest for therapies (treatments).

 

A vital sign of this: despite initial fears about the omicron variant of COVID-19, the 17th Annual HD Therapeutics Conference took place ­from February 28-March 3 at the Parker Palm Springs hotel in Palm Springs, CA. The 305 fully vaccinated attendees gathered under a massive tent, which allowed social distancing and provided good ventilation.

 

Shortly after the March 2020 conference, much of the world went on lockdown to avoid the ravages of the virus, pushing the 2021 conference online.

 

“I don't think it's hyperbole to say that coming here for this conference in person feels like a rebirth,” said Robert Pacifici, Ph.D., in a half-hour interview with me on March 4. “It's been a hard couple of years for everybody, but for the Huntington's disease community in particular.”

 

Dr. Pacifici is the chief scientific officer of the conference sponsor, CHDI Foundation, the nonprofit virtual biotech entity geared solely towards finding HD therapies. CHDI is the largest private funder of HD research.

 

In March 2021, the community “learned that two of the really well thought-out and very rational clinical trials for Huntington's disease had been halted and it dashed a lot of people's hopes,” recalled Dr. Pacifici, referring to GENERATION HD1, the largest clinical trial in HD history, run by Roche, and two smaller trials with a similar drug run by Wave Life Sciences.

 

Those results “must have been devastating” for people awaiting an “efficacious treatment,” Dr. Pacifici continued. “But we do what the Huntington's community always does: we persevere, we lift ourselves up by our bootstraps, and we go forward.”

 

Witnessing a “bunch of reasons” for hope about therapies at the conference, Dr. Pacifici declared, “I'm reinvigorated and very optimistic.”

 

For an overview of the conference and my interview with Dr. Pacifici, watch the video below.

 

 

Above, HD Therapeutics Conference attendees view scientific posters presenting new research, and, below, watch one of the many presentations at the four-day event (photos by Gene Veritas, aka Kenneth P. Serbin).

 

 

Learning from last year’s setbacks

 

At the Therapeutics Conference, Roche elaborated on new data from GENERATION HD1 and its plans to develop an improved clinical trial. Wave provided an update on its new early-stage trial, SELECT-HD.

 

Both firms use gene silencing drugs to attempt to reduce the amount of the toxic huntingtin protein in the brain (called huntingtin lowering). Both seek to build on the lessons learned from the 2021 setbacks.  (Click here to read about Roche’s recent announcement and here about Wave’s new trial.)

 

“I'm heartened that there's still a lot of enthusiasm for the huntingtin-lowering approach,” Dr. Pacifici observed. “There's actually a very impressive portfolio of other companies, therapeutic modalities, and approaches to huntingtin-lowering.”

 

Other plans to attack the mutant protein

 

PTC Therapeutics and Novartis Pharmaceuticals presented updates on their respective ongoing clinical trials using different huntingtin-lowering approaches. Whereas Roche and Wave drugs were administered via an uncomfortable spinal tap done at a clinic, PTC and Novartis use so-called small molecules: pills.

 

Besides the obvious convenience, such small-molecule drugs offer other key advantages, Dr. Pacifici explained.

 

“We know that mutant huntingtin is expressed everywhere [in the body] and so it’s good to know that you can lower it everywhere with a small molecule,” he said, noting that dosages can then be calibrated to achieve different lowering effects.

 

A higher dose creates more lowering, while a lower dose lessens it, Dr. Pacifici explained.

 

“From a safety perspective, if we ever found a long-term problem with huntingtin lowering, you can stop taking the compound and let the huntingtin come back so that then you can decide,” he continued, referring to a practice called picket-fence dosing, in which patients stop and restart dosing as needed.

 

Triplet gears up to test its approach

 

With no guarantee that reducing the toxic protein will result in an effective treatment, the Huntington’s field has purposefully diversified.

 

A key example is the work of Triplet Therapeutics. Triplet focuses on somatic expansion (also known as somatic instability), the tendency in HD of the already expanded (and therefore mutant) huntingtin gene to continue growing in length with age. The greater the expansion, the earlier the impact of the mutation on brain cells. This process is governed by recently discovered modifier genes that slow or hasten disease onset. (Click here and here to read more.)

 

“That's what actually causes the cells to malfunction, to die, and eventually leads to the underlying physiology of Huntington's,” Dr. Pacifici said. “So, not surprisingly, that gives us another therapeutic handle. Can we slow down that somatic instability?”

 

At the conference, two Triplet scientists presented a preliminary analysis of data from SHIELD-HD, a research study of 70 presymptomatic and early-disease-stage carriers of the HD mutation. SHIELD-HD is furnishing data for a clinical trial of Triplet's drug candidate, TTX-3360, aimed at blocking somatic expansion and, therefore, potentially delaying or avoiding HD onset.

 

Triplet Therapeutics scientists Irina Antonijevic, M.D., Ph.D., the chief medical officer (right), and Peter Bialek, Ph.D., senior director of translational science, after their presentation at the HD Therapeutics Conference (photo by Gene Veritas)

 

Founded in 2018, Triplet has used the science of somatic expansion and HD modifier genes to move with “record-breaking speed” towards a clinical trial, Dr. Pacifici said.

 

In a brief interview after the Triplet presentation, Irina Antonijevic, M.D., Ph.D., the company’s chief medical officer, confirmed that it will file a Clinical Trial Application this summer for permission to start a Phase 1 dose escalation clinical trial of TTX-3360, mainly to test safety and tolerability. Regulatory agencies can take a few months to review the application, after which the firm could start recruiting people with HD.

 

“We’re very excited,” Dr. Pacifici said. “The whole area of somatic instability is a great complement to huntingtin lowering. It's possible that eventually, if God forbid, huntingtin lowering turns out not to be viable, we've got a great backup plan. But even if it is, these things could actually synergize with each other. I could imagine people in the future being treated with a combination of therapies that address both of these things – lowering the huntingtin protein, but also preventing additional somatic instability.”

 

A future article will explore the SHIELD-HD presentation and Triplet’s clinical trial plans.

 

The value of family participation

 

Most of the conference presentations focused on human data, as opposed to research in animals. Dr. Pacifici pointed out that many advances in HD research result from the participation of thousands of gene carriers in studies and clinical trials.

 

“I appreciate that families are willing to give their time, their blood, their urine, and the travel, the poking, the prodding they're going through,” Dr. Pacifici said. “I want to express my heartfelt gratitude. This year, more than ever, I guess I'm happy to say I told you so, meaning that I always encourage people to participate and we're now seeing the fruits of that participation. We now have the evidence that those samples are being used judiciously and are providing unparalleled value.”

 

Dr. Pacifici also pointed to the steadfast commitment of both scientists and families to HD research during the pandemic, which “required people taking risk and going into the clinics and the labs.”

 

“Hang in there, be resilient, participate when you can,” Dr. Pacifici concluded, because a “really talented, committed global group of passionate drug discovery professionals would love nothing more than to deliver what you need so desperately, which are effective treatments for Huntington's disease.”

 

For my coverage of the start of the conference, click here.

 

For additional coverage, visit HDBuzz.