Soleno Therapeutics, Inc. operates as a biopharmaceutical company developing novel therapeutics for the treatment of rare diseases.
The company has submitted a new drug application (NDA) to the U.S. Food and Drug Administration (FDA) for its lead product candidate, diazoxide choline extended-release tablets (DCCR), for the treatment of Prader-Willi syndrome (PWS) in individuals four years and older who have hyperphagia. On August 27, 2024, the company announced that the FDA had accepted the NDA...
Soleno Therapeutics, Inc. operates as a biopharmaceutical company developing novel therapeutics for the treatment of rare diseases.
The company has submitted a new drug application (NDA) to the U.S. Food and Drug Administration (FDA) for its lead product candidate, diazoxide choline extended-release tablets (DCCR), for the treatment of Prader-Willi syndrome (PWS) in individuals four years and older who have hyperphagia. On August 27, 2024, the company announced that the FDA had accepted the NDA for filing, designated the application for priority review, and set a Prescription Drug User Fee Act (PDUFA) target action date of December 27, 2024. On November 26, 2024, the company announced that the FDA had extended the review period for its NDA and set a new PDUFA target action date of March 27, 2025. DCCR previously received Breakthrough Therapy and Fast-Track designations in the United States (U.S.), as well as Orphan Drug designations in the U.S. and European Union (E.U.).
DCCR contains diazoxide choline, a potent ATP-sensitive potassium (KATP) channel activator. The KATP channels play a central role in the regulation of a number of physiological processes, which may otherwise be dysregulated, contributing to the pathophysiology of several diseases.
Diazoxide Choline Extended-Release Tablets
DCCR consists of the active ingredient diazoxide choline, a choline salt of diazoxide, which is a benzothiadiazine. Once solubilized from the formulation, diazoxide choline is rapidly converted to diazoxide prior to absorption. Activating the KATP channel in NPY/AgRP neurons in the hypothalamus may reduce secretion of neuropeptide Y (NPY) and Agouti-related peptide (AgRP), contributing to a reduction in hyperphagia. Activating the KATP channel in the dorsal motor nucleus of vagus may potentiate the effects of leptin, insulin, and a-melanocortin stimulating hormone to reduce hyperinsulinemia and impact appetite and satiety. Activating the KATP in pancreatic ß-cells can reduce the secretion of insulin, and further reduce the accumulation of excess body fat and the progression to insulin resistance. Activating the KATP channel in adipocytes has the potential to decrease de-novo triglyceride synthesis and increase ß-oxidation of fat, reducing fat mass.
DCCR was formulated with the goals of improving the safety and bioavailability of orally administered diazoxide, and reducing the frequency of dosing required by current diazoxide formulations. Diazoxide choline has been formulated into an extended-release tablet that provides lower peak plasma concentration compared to diazoxide oral suspension, and allows for the gradual release of diazoxide choline from DCCR, making it suitable for once-a-day dosing. The gradual release and absorption of diazoxide achieved using DCCR results in consistent intraday circulating drug levels, potentially reducing the adverse events often associated with transiently high circulating drug levels, and providing efficacy at lower diazoxide-equivalent doses.
Clinical Trials of DCCR for PWS
A Phase 2 clinical trial (Study PC025) was a single-center, randomized withdrawal study to evaluate the safety and preliminary efficacy of DCCR in the treatment of PWS subjects. This study enrolled 13 overweight and obese subjects with genetically confirmed PWS who were between the ages of 11 and 21. This study included a 10-week open-label treatment phase, which was followed by a randomized double-blind, placebo-controlled withdrawal phase.
Key efficacy results included nominally significant reductions from baseline to the end of the open-label treatment phase in mean hyperphagia score, number of subjects reporting one or more aggressive and destructive behaviors, mean body fat mass, LDL cholesterol, and non-HDL cholesterol. There were also nominally significant mean increases in lean body mass and lean body mass/fat mass ratio that were associated with a nominally significant reduction in mean waist circumference, consistent with the loss of visceral fat.
Responders were randomized in a 1:1 ratio either to continue on active treatment at the dose they were treated with, or to the placebo equivalent of that dose for an additional 4 weeks. Of the 13 subjects who enrolled, 11 completed the open-label phase, and all were designated as responders; the remaining two subjects had discontinued prematurely.
DCCR was subsequently evaluated in a Phase 3 study (C601 or DESTINY PWS), a 13-week randomized, double-blind placebo-controlled study, which completed enrollment in January 2020, with 127 randomized participants at 29 sites in the U.S. and the United Kingdom (U.K.). Participants who completed DESTINY PWS and sought continued treatment with DCCR were eligible to receive DCCR in a long-term open-label safety extension study (C602). Top-line results from DESTINY PWS were announced in June 2020. Although the trial did not meet its primary endpoint of change from baseline in hyperphagia, significant improvements were observed in two of three key secondary endpoints.
In February 2021, the company announced an analysis limited to data collected before the onset of the COVID-19 pandemic. The analysis of the data through March 1, 2020, showed statistical significance in the primary, all key secondary, and several other efficacy endpoints. In September 2021, the company announced interim one-year data from the C602 open-label extension (OLE) period showing statistically significant reduction from pre-DCCR baseline in mean hyperphagia scores and all other PWS behavioral parameters, and statistically significant improvements compared to the natural history of PWS from the PATH for PWS Study (PATH) over a one-year treatment period. The PATH study was sponsored by the Foundation for Prader-Willi Research (FPWR) to advance the understanding of the natural history in individuals with PWS. The FDA recommended that additional controlled data be included in an NDA submission.
In March 2022, the company submitted an amended protocol that incorporated a randomized withdrawal (RW) period to Study C602 to obtain additional controlled data requested by the FDA, and the FDA acknowledged that data from the study had the potential to address its concerns about the efficacy of DCCR. The RW period of Study C602 was a multi-center, randomized, double-blind, placebo-controlled study of DCCR in 77 patients with PWS at 17 sites in the U.S. and 5 sites in the U.K. The RW period consisted only of patients previously enrolled in the Study C602 OLE period and did not enroll any new patients. The company announced the initiation of the RW period for Study C602 in October 2022, and completed enrollment in May 2023.
On September 26, 2023, the company announced positive statistically significant results for the primary endpoint from the RW period of Study C602. The company submitted its NDA for DCCR to the FDA on June 27, 2024. On August 27, 2024, the company announced that the FDA had accepted the NDA for filing and priority review, and set a PDUFA target action date of December 27, 2024. On November 26, 2024, the company announced that the FDA had extended the review period for its NDA and set a new PDUFA target action date of March 27, 2025.
Regulatory Status of DCCR for the Treatment of PWS
Diazoxide choline is being developed in the U.S. under a current Investigational New Drug Application (IND), and has Breakthrough Therapy and Fast-Track designations in the U.S., as well as Orphan Drug designations in the U.S. and E.U.
On April 29, 2024, the company announced that the FDA granted Breakthrough Therapy Designation to diazoxide choline for the treatment of adults and children ages 4 years and older with genetically confirmed PWS who have hyperphagia.
Sales and Marketing
The majority of the PWS population in the U.S. is diagnosed shortly after birth through an affordable genetic test, and the patient, as well as their treating physician, are captured in a commercially available reimbursement claims database. Based on the company’s analysis of this database, approximately 300 healthcare providers are either directly prescribing or influencing the prescription of approximately 40% of the PWS patient population. Patients with PWS are typically treated by a multi-disciplinary team led by a pediatric or adult endocrinologist, and many families and patients receive care at larger clinics that devote specific resources to caring for people with PWS. The PWS care teams with the largest volumes are often in university-associated hospitals or children’s hospitals, and a portion of adults with PWS live in residential group home settings.
In anticipation of FDA approval of DCCR, the company is building out its commercial organization across Marketing, Sales, and Patient Support functions to support demand, with the goal of delivering an exceptional provider, patient, and caregiver experience. The company has substantially completed hiring of all senior leadership roles in the commercial team, including adding industry veterans with extensive experience in the rare disease space, and is in the process of onboarding a field force of approximately 30 individuals.
The commercial team has already made substantial progress in executing on its foundational commercial strategy, including extensive demand assessment and marketplace analysis, payer research and outreach, selection and submission of a proprietary name, selection of an advertising agency, onboarding of a special pharmacy partner to provide patient, caregiver, prescriber, and payer services, obtaining relevant state licensures, the implementation of a customer relationship management system, and the development of a patient services program. The specialty pharmacy will also serve as the company’s point of contact for inbound healthcare provider and patient inquiries, prescription processing, insurance investigation, and patient onboarding.
Manufacturing
The company and its third-party manufacturers are subject to cGMPs, which are extensive regulations governing manufacturing processes, stability testing, record keeping, and quality standards as defined by the FDA and the EMA.
Intellectual Property
DCCR Patent Portfolio
The company’s patent portfolio consists of issued U.S. patents and pending U.S. applications. The 20-year expiration dates of the company’s issued U.S. patents are between 2025 to 2035. The company also has issued patents in Europe, Canada, Japan, China, India, Israel, Hong Kong, Australia, Malaysia, Mexico, New Zealand, Singapore, Indonesia, Korea, and Eurasia. The company is prosecuting numerous patent applications in major pharmaceutical markets around the world. The issued patents and pending patent applications include protection of compositions, methods of manufacturing, pharmaceutical formulations, and methods of treating aspects of PWS and Smith-Magenis syndrome (SMS).
Government Regulation – Pharmaceuticals
The company conducts certain healthcare transactions electronically; it is presently a Covered Entity, and must have in place the administrative, physical, and technical safeguards required by HIPAA, the Health Information Technology for Economic and Clinical Health Act of 2009 (HITECH Act), and their implementing regulations.
The company is subject to comparable state laws, some of which apply to all payers regardless of source of payment, and do not contain identical exceptions to the Stark law.
Research and Development
The company’s research and development expenses were $78.6 million for the year ended December 31, 2024.
History
The company was incorporated in the state of Delaware in 1999. It was formerly known as Capnia, Inc. and changed its name to Soleno Therapeutics, Inc. in 2017.