There are a number of points that I think are worth noting from the Biogen Q4 2024 Earnings Call.
Firstly, other than Skyclarys, Reata was developing a second drug for the treatment of diabetic peripheral neuropathic pain. At the time of Reata’s acquisition by Biogen, this asset was just entering Phase 2. Although that study is yet to read out, Biogen last night announced that this program has been chopped.
Secondly, I think it’s worth reading Biogen CEO Chris Viehbacher’s comments on the challenges of launching and marketing a rare genetic disease drug. Note that he stresses that quarterly sales are likely to be lumpy in nature
…by its very nature, it is unfortunately not going to be the nice smooth progression quarter on quarter…
We expect to see continued steady growth out of Skyclarys. But again, I appreciate that it's going to be hard for some of you to model on a quarterly basis.
Christopher Viehbacher -- President and Chief Executive Officer
Skyclarys in Friedreich's ataxia, again, very first treatment for Friedreich's ataxia. We have been able to determine from basically medical claims data that there are approximately 4,800 patients in the U.S. That's about what we thought. One of the complexities is that it's harder to find these patients because you could have a primary care physician in a rural setting that has one single patient and you have to go find them.
And we're talking to primary care physicians, talking to cardiologists, talking to pediatricians. So it's quite a large prescriber base for a very narrow patient population. But that, of course, is the core of what rare diseases does. I remember years ago, when we acquired Genzyme when I was at Sanofi and the marketing folks are saying, our marketing strategy is looking for needles in haystacks.
And that is exactly what rare disease is all about, and it's what Biogen is also very good at. And of course, today, we've got a lot more technology. We can use tools such as AI and genetic testing to help find those patients, but by its very nature, it is unfortunately not going to be the nice smooth progression quarter on quarter. That said, we are particularly proud to say that we have been able to double the number of patients on treatment in the past year.
Not all of those are yet being reimbursed. We are able to get a lot of patients on drug and then negotiate with governments, particularly in Europe to get the reimbursement and once we do that, the patients flip from being free goods patients to actually revenue-generating treatments. There's always a bit of a -- in each country, a number of patients who are diagnosed who have been waiting for treatment and you can get those quite easily. There are a number of older patients who actually have lived with this disease for 30, 40 years.
And they are the ones we actually have to go hunt for. We will see another growth driver this year and that we expect to get approval for Skyclarys in Latin America. I was in Brazil last year and there are quite a number of patients in Latin America. So as we started with the U.S., we moved to Europe and then we're moving to South America and indeed areas of the Middle East.
We expect to see continued steady growth out of Skyclarys. But again, I of appreciate that it's going to be hard for some of you to model on a quarterly basis.
Thirdly, I want to bring attention to the matter of diagnosed patient population. At the time of Skyclarys launch, Reata stated that there were approximately 5,000 people in the US with diagnosed Friedreich’s ataxia. Despite use of “tools such as A1 and genetic testing to find these patients”, CEO Viehbacher last night put the identified number at 4,800. So, in two years, there has been no growth seen in the diagnosed patient population. In comparison, at the time of DayBue launch, Acadia stated that the diagnosed Rett patient population in the US was approximately 4,500. Most recently, Acadia has reported that the diagnosed population has grown in the past two years to 6,000 – a one third increase.
Finally, I want to compare the US quarterly sales of Skyclarys, now marketed by Biogen for almost 18 months, with those of DayBue. Keeping in mind that Biogen is a US$20bn market cap pharma v. Acadia ~US$3bn and that DayBue patient retention has been challenged by the issue of diarrhoea, I think that one must give Acadia credit where it is due.
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