Soleno Therapeutics Updates Prader-Willi Syndrome Launch and European Regulatory Progress

Executives from Soleno Therapeutics provided an update on the company's commercial launch in Prader-Willi syndrome (PWS), reimbursement dynamics, and regulatory progress in Europe during Guggenheim's 2026 Emerging Outlook Biotech Summit. Soleno said it is a commercial-stage rare disease company with an approved product for PWS, a genetic disorder where a central feature is hyperphagia, described as an insatiable desire to eat.

Management characterized the product as the first approved treatment for the disease and said the drug has been on the market for "about 3/4" (approximately three quarters). While the company declined to discuss the current quarter's performance, executives reiterated a longer-term view of launch progress. The CEO said investors should think about roughly 10% of total addressable market (TAM), equating to about 1,000 start forms over a nine- to 12-month period, with quarter-to-quarter variability.

The company also said it expects the first-quarter report to be the last time it discloses start-form metrics, after which it plans to shift toward more traditional reporting focused on revenue and active patients. Soleno indicated it is not currently planning to provide full-year guidance, citing the need for the business to mature further and for the company to better understand "ebbs and flows" in launch dynamics, though management said guidance remains "on the table" once it is comfortable.

Reimbursement has been better than expected with coverage through almost 48 Medicaids and Medicare cited as a strong payer, the prescriber base tops 600, and European regulatory momentum continues with Day 180 questions expected end of February for an EU4+UK patient pool of approximately 9,500. Progress toward EMA approval of DCCR in Europe, where approximately 9,500 additional PWS patients are concentrated in major markets with high diagnostic rates, offers a clear international expansion opportunity.

The CFO outlined the company's process for converting start forms into treated and revenue-generating patients. Start forms are submitted by prescribers and processed through the company's specialty pharmacy partner, Panther, which checks completeness and performs payment assessment. The process can take roughly 30 to 45 days and a single-digit percentage may be canceled before reaching the active patient base, citing reasons such as administrative errors or family timing issues.

Once drug is shipped, the patient enters the active base. Some discontinuation is expected, pointing to long-term clinical evidence suggesting overall discontinuation in the 15% to 20% range. That range was described as healthy in a rare disease setting with comorbidities. Active patients may be in a "paid" or "free" bucket due to socioeconomic support, quick-start programs, or bridging during coverage transitions. Revenue is driven by active paid patients, adherence, wholesale acquisition cost (WAC), and gross-to-net.

Management said it does not expect the holiday-related variability seen in the fourth quarter to be present in the first quarter, given the absence of major holidays. However, executives emphasized that revenue can experience first-quarter seasonality due to higher gross-to-net discounts. Insurance copay resets can increase patient out-of-pocket costs, which can raise the company's copay assistance spending and therefore increase gross-to-net. In addition, coverage disruptions when patients switch plans can temporarily move patients from paid to free drug through bridging programs, also affecting gross-to-net. The company did not comment on whether revenue would decline sequentially, emphasizing instead that the key metric is continued active patient growth.

Executives discussed adverse events observed in the real-world setting for VYKAT XR, stating that the types of adverse events appear consistent with the label and clinical trial experience. Listed events include fluid retention, hyperglycemia, rash, and hypertrichosis, and reported events are predominantly non-serious. The CEO cautioned that raw counts may appear higher because the company has treated "almost 10 times as many patients" commercially as in clinical trials, but said the percentage trends appear similar.

On discontinuations, management clarified that a previously cited roughly 12% discontinuation rate in the fourth quarter was adverse event-related, while overall discontinuation was approximately 15%. Based on both trials and early commercial experience, adverse event-related discontinuations tend to occur earlier in treatment, suggesting that patients who remain on therapy beyond an initial period may be more likely to persist, while noting that data are not yet mature enough for firm predictions.

Regarding titration, the CEO said the company believes the vast majority of patients are reaching their prescribed dose, with a minority titrating differently due to comorbidities or severe obesity. The label's six-week titration framework broadly matches expectations.