Amicus’s Pompe disease setback doesn’t dent gene therapy enthusiasm

The FDA asks Amicus for more data on its Pompe disease candidate, but the company is already looking towards a Fabry disease gene therapy, and has made a remarkable pricing pledge.

Amicus will have to wait a bit longer to get its Pompe disease candidate AT-GAA to the US market. The FDA has said existing data are not enough for accelerated approval, echoing the stance taken by European regulators in July.

The company’s stock opened down 4% this morning before recovering slightly; accelerated approval had always been a long shot, and Amicus is confident that it is a question of when, not if, it will file AT-GAA. And the group is already looking further into the future, expecting to unveil several gene therapy candidates by the end of this year, its chief executive officer, John Crowley, told Vantage.

At least one of these will be in Fabry disease, the rare disorder currently addressed by Amicus’s first approved therapy, Galafold. Mr Crowley had strong words for any investors worried that a gene therapy might cannibalise sales of its existing product, saying: “We have a duty to 'obsolete' our own technologies.”

He continued: “I think it’s the right thing for patients and shareholders, because if we don’t do it somebody else will. I’d be very disappointed if the only new medicine invented in Fabry during our lives was Galafold. I think it’s a very important step forward for treatment, but it’s not a cure.”

Mr Crowley would not give more details on the gene therapy candidates that the company planned to acquire, but said: “We’re looking at a range of opportunities from academic [centres] and private and public companies. We’re not commenting on the specific stage; some programmes we’re evaluating are clinical stage and some are preclinical.”

More information could be available as soon as soon as Amicus’s R&D day on October 10.

Pompe pause

Still, any gene therapy candidate will likely be several years from the market, and Amicus could have done with some good news with AT-GAA, which Mr Crowley has previously described as Amicus’s crown jewel.

The company had hoped to get a green light based on an ongoing phase I/II study, but the FDA has sent it back to gather more data, including results from a new 10-patient cohort in the phase I/II trial, due next year, and data from a natural history study of patients treated with enzyme-replacement therapy, set to read out in the second half of this year.

Amicus hopes that this will be enough to make another bid for US accelerated approval in 2019, but Leerink analysts have pushed back the expected launch of AT-GAA to 2022, suggesting that the agency will need to see data from a larger phase III trial due to start this year.  

That 100-patient study will compare AT-GAA against enzyme-replacement therapy, with a primary endpoint of six-minute walk test.

Today’s stock reaction comes not long after the sell-off that coincided with US approval for Galafold. Mr Crowley was adamant that this was not down to the drug’s $315,000 per year price tag, saying this was lower than the cost of the previous standard of care, Sanofi’s enzyme-replacement therapy Fabrazyme, which comes in at around $340,000 per year.

However, Sanofi has reportedly put Fabrazyme’s average price tag at closer to $290,000 when taking into account children who need less of the drug.

Mr Crowley pointed to Galafold’s greater convenience as an oral small molecule rather than an injected therapy, and said Amicus’s drug could lower treatment costs overall: “We’ll be able to save the system tens of thousands of dollars per patient per year in infusion costs.”

Pricing pledge

As well as setting what it believes is a responsible price tag at launch, Amicus has promised not to raise the cost of Galafold by more than the US inflation rate – specifically the consumer price index. “And that’s for the entire life of the medicine,” Mr Crowley said. “To our knowledge no pharma company has ever made that promise before.”

Of course, drug pricing is a hot topic right now and it will be interesting to see whether Amicus sticks to its bold pledge if and when the current furore dies down – and, if Amicus were acquired, whether a new company would take the same approach.  

Mr Crowley highlighted another “unique” promise Amicus has made: to “take a meaningful portion of the revenue from Galafold and reinvest it, specifically into Fabry disease, until there is a cure.”

He said this was different from simply putting money back into R&D – the long-time defence of biopharma companies trying to justify high drug prices.

Mr Crowley would not say what constituted a “meaningful portion”, adding that it would be unhelpful to earmark a certain percentage of sales for this purpose, “because in some cases we’ll spend more than whatever predefined percent, but in other cases we might not have the ability to spend at a predefined rate”.

But he said that this year alone in Fabry disease the group would spend “many millions of dollars” on gene therapy. He admitted that it could be a “many-decades commitment” before a Fabry disease cure is developed.

After being punished for raising hopes of accelerated approval in Pompe disease, Amicus will have to hope that its latest promises do not come back to haunt it.

Study Trial ID
Phase I/II Pompe disease trial NCT02675465
Natural history study (POM-003)  NCT03347253
Phase III trial (ATB200-03)  N/A

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