The HEALEY Platform Trial: Quick Failures and New Hope for ALS

Clinical wins have been few and far between for the HEALEY ALS Platform Trial. A heterogeneous patient population and delays have posed challenges, with several biotechs discontinuing programs based on underwhelming results. But optimism persists among the trial’s leaders and early participants, with two companies, Clene Nanomedicine and Prilenia Therapeutics, moving their investigational amyotrophic lateral sclerosis (ALS) treatments forward.

The first seed for an ALS platform trial was planted when Massachusetts General Hospital’s Merit Cudkowicz read an article on master platform trials by former FDA Principal Deputy Commissioner Janet Woodcock. “I read that one and thought it might be appropriate for ALS,” Cudkowicz told BioSpace.

Then, along came Sean Healey, a prominent American businessman who had recently been diagnosed with ALS, with an attractive opportunity. He said, “I might not save myself from this illness, but I want to make a difference. Give me a proposal,” Cudkowicz recalled. So she and her team worked around the clock, ultimately pitching the platform trial, and “[Healey] loved it. He just got it right away, that it was efficient and good for patients.”

Healey, in partnership with his global asset management firm, Affiliated Managers Group (AMG), donated $40 million to launch the Sean M. Healey & AMG Center for ALS at Mass General, and set in motion a new chapter in ALS research. Cudkowicz serves as the center’s director.

Biopharma quickly jumped on board with the platform trial, with dozens of companies—in addition to Clene and Prilenia, UCB, Biohaven Pharmaceutical and Seelos Therapeutics—vying to be a part of it.

Fast forward four years and none of these drugs has hit the trial’s primary endpoints.

But Clene CEO Rob Etherington said that doesn’t reflect a failure of the study itself. The HEALEY trial was designed to “fast fail” assets that don’t have utility, he explained, “and it worked in that respect, for a few of the regimens.”

Indeed, Cudkowicz noted that Biohaven, which ultimately opted against moving forward with the program, also viewed the trial as a success because “they got a quick answer, a clear answer.” Biohaven did not respond to BioSpace’s request for comment.

But perhaps most notably, Clene and Prilenia showed positive data on secondary endpoints that prompted those companies to progress their candidates, Cudkowicz said. “So, I really actually view that as a success.”

To select the initial round of participants in the trial, Cudkowicz and her team decided to host a competition. She noted that many aspiring platform trials seemed to be stuck at the funding stage and believed a call for proposals would speed up the process. The prize: entry into the Healey ALS Platform Trial, where some costs for the first companies would be covered.

The team received 30 proposals from all over the world. Cudkowicz and her colleagues assessed each therapy based on clinical potential, mechanism of action, and diversity of approach. “We did want to pick drugs with different targets for the first five,” Cudkowicz said.

Finally, they selected five programs. UBC’s zilucoplan inhibits complement component 5, the dysregulation of which is implicated in ALS, while Biohaven’s verdiperstat blocks the enzyme that reduces oxidative stress and neuroinflammation. Clene’s CNM-Au8, by contrast, is an oral, liquid suspension of gold nanocrystals designed to improve the survival, function, and communication of nerve cells. Prilenia’s pridopidine is also a neuroprotective agent, and Implicit Bioscience’s IC14 is an anti-CD14 monoclonal antibody devised to regulate the pathogenic inflammatory responses to infection and injury.

Of these, Clene and Prilenia fared the best. Although both companies’ assets missed their primary endpoints, positive biomarker data and benefit to a subgroup of patients in Prilenia’s case supported moving the programs forward.

With Prilenia’s candidate, a subgroup of patients with early-stage ALS who were rapidly declining had “substantially less decline” in ALS Functional Rating Scale-Revised (ALSFRS-R) total score compared to placebo. The company has stated plans to launch a Phase III trial.

Meanwhile, Clene has a briefing book in front of the FDA based on HEALEY data and additional biomarker results gleaned from the RESCUE-ALS trial and survival data from ongoing compassionate use protocols. While the agency originally said the data were insufficient to support a new drug application, Clene has since submitted more information, including mechanistic and ALS-specific biomarkers and data on a super-responder group, which Etherington said is now under review.

Clene also gathered promising survival and biomarker data from its arm of the HEALEY study. Treatment with CNM-Au8 for up to 133 weeks decreased the risk of death by 49% compared to PRO-ACT database–matched placebo, according to Clene, while also reducing levels of neurofilament light chain (NfL), which is gaining ground as a predictor of clinical outcomes in neurodegenerative diseases. “Without the survival secondary endpoint win and the exploratory endpoint win and the neurofilament biomarker win that HEALEY gave Clene, we’d be in a very different position today,” Etherington said. “We certainly wouldn’t have a briefing book under consideration at the FDA without HEALEY.”

The other companies have either shut down their programs or are still determining next steps. Implicit never moved forward to the design phase. UCB’s arm of the trial was stopped early after an interim analysis demonstrated futility, according to a Massachusetts General press release. Meanwhile, Biohaven’s verdiperstat failed to statistically differentiate from placebo, and the drug is no longer listed in the company’s pipeline.

Seelos joined after Implicit departed and got mixed results. The company stated in a March press release that while its drug trehalose failed to meet statistical significance in the primary and secondary endpoint in the HEALEY study, it showed a “potential signal of efficacy” in a subgroup of patients not taking Amylyx’s Relyvrio, which was given to some trial participants after its approval in September 2022.

And the HEALEY trial marches on. In July 2022, Calico Life Sciences signed on to test ABBV-CLS-7262, and Denali Therapeutics announced its participation with DNL343 in December of the same year. Data from these arms of the trial are expected in early 2025. Another company, Australian outfit PharmAust, recently committed to studying its drug monepantel, and Cudkowicz said talks are ongoing with several more companies.

Cudkowicz said that no matter what the result of the various arms, “you can learn a lot about [ALS].”

Platform trials are a fairly new phenomenon, and Cudkowicz shared that she learned a lot from the DIAN Alzheimer’s trial at Washington University. The model offers myriad benefits, including efficiency. While a clinical trial typically takes more than a year to get off the ground, the HEALEY study is a perpetual trial, meaning a new drug regimen can be added in just 30 days.

It’s also patient-centric. The use of a shared placebo between all regimens means that more patients receive a potentially efficacious drug. This also means companies have to recruit fewer patients.

The fact that some of their costs were covered was a significant benefit for the smaller companies in the HEALEY trial. Prilenia, for example, had six employees at the time it applied to join the trial. “The good news was they paid for the drug, so we didn’t have to raise money for [that],” CEO Michael Hayden told BioSpace. The infrastructure build and support were also partially funded by several foundations, Cudkowicz said.

“I’m grateful. Without HEALEY, we would never have done this trial,” Hayden said. “We didn’t have the money.”

The companies involved also have access to elite experience in the ALS space. Cudkowicz is widely considered to be the dean of ALS drug development, and both Etherington and Hayden referenced the gravitas associated with the HEALEY trial, which includes 75 research sites.

“The advantage of HEALEY is undeniably the fact that you have an easy network of top expert centers . . . so you’re really able to access the top centers in the United States of America,” Etherington told BioSpace. “That is a tremendous advantage for young startup companies to have access to and to be involved with.”

Etherington added that acceptance into the trial gave CNM-Au8 credibility “because it really was a testament of others’ stamp of approval that are well respected in the space.”

Still, a complex structure with so many moving parts is bound to take time to perfect.

Etherington noted that every drug is unique, and “a platform study does not enable an individual drug and its unique aspects of mechanism or side effects or administration to actually make any changes” to the trial’s protocol.

For example, each cohort in the HEALEY trial has run for six months. For CNM-Au8, this was too short of a window to prove efficacy, Etherington said. “To have everybody come in and have to fit the framework with no exceptions, that’s a challenge.”

Notably, Cudkowicz shared that the team is currently considering amending the protocol based on learnings from the first five regimens. “This includes possibly longer duration of follow up on the randomized controlled trial period to address the possibility that some medications need more time to achieve biological and clinical effects,” she said.

Cudkowicz added that a voice app developed by Aural Analytics and used in the first four regimens is “turning out to be a very good digital biomarker. We also did home spirometry (a measure of lung function), which looks pretty much just as good as in clinic.”

Another challenge for a trial with multiple centers across the U.S., Etherington said, was an initial delay in receiving data from every center, though Clene is now in possession of the final datasets from the HEALEY trial.

Because every regimen starts at a different time, they all finish at different times, slowing down the rate at which results are available. For a company conducting a single study, “all hands are on deck,” Etherington said. By contrast, in a platform trial, “we have to be more ecumenical. We have to share, as it were, the load and the timeline, and we need to recognize that the company’s individual interests need to be subjugated, to some degree, to the whole of the platform study.”

Hayden agreed, saying that the HEALEY team was sometimes “overwhelmed” with running what amounts to eight trials, and that there sometimes is “a little frustration in terms of the speed of response, the ability to get statistical analysis done. All of that can be slower than we would like.”

Cudkowicz acknowledged that the trial has faced challenges in this regard. “Since the idea of platform trials is efficiency and speed, we want all parts of it to be efficient,” she said. “Some of the structural, operational things that slow down trials in general are still in play in platform trials [and] how trials are started up at academic institutions is still too slow, in my opinion. We have some new initiatives to improve this dramatically for the next several new regimens,” she said in an email.

Cudkowicz added that interest in the trial overwhelmed the capacity of some of the trial sites. “There’s high interest in it from the companies, from the patients, but now we’ve gotta do it even faster.”

A heterogeneous patient population was another challenge, Hayden said. “The study included essentially everybody with ALS, and that was maybe . . . both positive and negative. The positive was that this gave hope to everybody.” However, ALS has a “very heterogeneous population.”

The HEALEY trial included patients with definite, probable and possible ALS, as well as those more than three years out from diagnosis. “We were concerned about that right in the beginning because we knew that all the trials that had been successful in ALS had a different population” that included patients with only definite and probable ALS, and a shorter disease duration, Hayden said.

Prilenia ultimately prespecified that it wanted to also study pridopidine in patients with early-stage ALS, diagnosed less than 18 months before the trial’s start, and HEALEY investigators were able to recruit from such a population for the arm of the trial testing the drug. And while pridopidine failed the primary endpoint in the full analysis set, in patients with early ALS, “what we saw is that we had a very wonderful positive effect,” Hayden said.

“We delayed progression for the first time ever seen in an ALS trial at eight weeks.”