Will Soleno Therapeutics’ patents protect against generic competition for its anticipated DCCR drug?
Zachary Silbersher
Soleno Therapeutics is anxiously awaiting FDA approval on its extended-release formulation of diazoxide choline (DCCR), which is indicated for treating Prader-Willis syndrome (PWS). Soleno’s drug has already received breakthrough designation status from FDA, as well as orphan drug designation. Together, that suggests that if Soleno’s drug is approved this month, it will receive FDA-approved exclusivity for seven years. Yet, after that, which patents does Soleno have that it can use to delay entry of generics? (Update, on March 26, Soleno’s DCCR drug was approved by the FDA as Vykat XR.)
To date, Soleno appears to have more than a handful of issued patents and pending applications covering its upcoming DCCR drug. Soleno’s latest 10-K indicates that its “patent portfolio consists of issued U.S. patents and pending U.S. applications,” and the expiration dates for the U.S. patents are “between 2025 to 2035.” (2024 10-K at 7).
Since Soleno’s DCCR drug is not yet approved, its patents are not yet listed in the Orange Book. At the bottom of this post are some of the patents that appear to be owned by Soleno that may cover its DCCR product. (The description of the Patent Type are summaries—an actual description of the claimed inventions, which are much longer than what is provided below, are available in the claims for each respective patent.)
Given that Soleno’s DCCR drug has been awarded orphan drug exclusivity, that indicates that the drug’s FDA-approved exclusivity will be seven years. If approved today, Soleno’s drug could be free from generic competition until 2032, even without assertion of any patents. Given that, any patents expiring before 2032 are essentially irrelevant to preserving freedom from generic competition before that date.
With the exception of the ‘777 patent and the ‘202 patent, most of Soleno’s patent appear to be method of use patents. The ‘777 patent appears to be a polymorph patent, and the ‘202 patent appears to be a method of preparing the compound. These patents, however, are slated to expire sometime in 2026. Indeed, as shown above, many of Soleno’s patents are slated to expire long before expiration of DCCR’s orphan drug exclusivity.
On the other hand, Soleno’s other patent family includes patents slated to expire in roughly 2034 or 2035. These later-expiring patents are generally directed to methods of treating patients with Prader-Willi Syndrome (PWS) or Smith-Magenis syndrome (SMS), and in some cases, both conditions. That matters because, Soleno’s DCCR drug appears to be indicated only for PWS, in which case, the patents that are directed to methods of use for SMS only will likely be inapplicable to excluding generics. On the other hand, Soleno appears to have contemplated using DCCR for the treatment of SMS as well. If Soleno completes additional trials and successfully adds SMS as an FDA-approved indication, those patents could become applicable in the future.
Another major factor that could impact the extent of DCCR’s monopoly life is whether Soleno will be capable of successfully petitioning for Patent Term Extension (PTE). PTE can extend the life of applicable patents by up to five years. PTE is awarded to brand pharmaceuticals companies based upon delays by FDA in approval of a drug covered by the particular patent. The petition is made to the Patent Office, even though it is based upon delays by FDA. In theory, if PTE is awarded in this instance, it could extend the lifetime of one of Soleno’s patents that cover its DCCR drug by an additional five years. Given that only a single patent is technically required to exclude generics, PTE could, in theory, preserve DCCR’s monopoly pricing until roughly 2040.
PTE is technically available only for a single patent based upon delay of FDA’s regulatory review period for a given drug product. Patents that cover an active ingredient or method of use of an FDA-approved product are eligible. That means, in theory, that all of Soleno’s patents that cover the approved indications for its DCCR drug are likely eligible for PTE. That said, a petition for PTE is neither guaranteed, and even if PTE is granted, the additional patent life awarded can be less than five years.
All of this, in turn, suggests that Soleno may be strategic about which patent it selects to petition for PTE. Presumably, if it wishes to fortify its DCCR patent portfolio to exclude generics for as long as possible, then it may select one of its patents that already expire the latest (i.e., around 2034 or 2035.). Soleno may likely focus on a patented method that is closest to the approved FDA indication so as to increase the likelihood the patent will be infringed. Soleno may also focus on a patent covering an indication that is least likely to be carved out under section viii, which could permit earlier entry by generics with a skinny label.
Soleno could also extend the life of its patents through Patent Term Adjustment (PTA). Unlike PTE, PTA is awarded for delays due to the Patent Office. When PTA is awarded, it is typically limited to a few months, and in some cases, a couple of years. Five years of PTA would be considered a lot. A review of Soleno’s patents that expire within the 2034/2035 range, however, suggests that none of them have been awarded any PTA. PTA is typically awarded when a patent issues.
Finally, Soleno appears to have pending patent applications that may also cover its DCCR product. Some of these applications may not yet be published, and therefore, may not yet be public. Soleno can technically continue to add to its patent portfolio over the next seven years while its drug is protected by FDA-approved exclusivity. Those new patents, particularly if they evolve out of new patent families, could theoretically yield expiration dates past 2035.
