Soleno Therapeutics Announces Publication of Results from Pivotal Study of VYKAT™ XR in the Journal of Clinical Endocrinology and Metabolism

Rhea-AI Summary

Soleno Therapeutics (NASDAQ: SLNO) announced publication in the Journal of Clinical Endocrinology and Metabolism of results from a 16-week randomized withdrawal study (C602-RWP) of VYKAT XR (diazoxide choline extended-release) in people ≥4 years with hyperphagia in Prader-Willi syndrome (PWS).

The study randomized 77 participants (VYKAT XR n=38; placebo n=39). Withdrawal to placebo produced statistically significant worsening in hyperphagia (HQ-CT, P=0.0022). Placebo participants gained more weight (LS mean difference -1.6 kg; 95% CI -3.1, -0.1) and had larger BMI z-score increases (LS mean difference -0.09; 95% CI -0.17, -0.01). No serious adverse events occurred in the VYKAT XR arm.

Positive

• FDA approval as first treatment for hyperphagia in PWS
• Randomized withdrawal: HQ-CT worsening P=0.0022
• Weight difference favoring VYKAT XR: 1.6 kg LS mean
• No serious adverse events in the VYKAT XR treatment arm

Negative

• CGI-S and CGI-I approached but did not reach statistical significance
• Randomized withdrawal cohort was 77 participants, limiting sample size

Key Figures

Phase 3 program size 127 participants Comprehensive Phase 3 clinical program for VYKAT XR in PWS

Drug exposure Over 400 patient years Total exposure to VYKAT XR including nearly six years continuous use

Study duration 16 weeks Randomized withdrawal period study (C602-RWP) length

Randomized participants 77 individuals Participants entering 16-week randomized withdrawal after prior Phase 3 studies

Treatment allocation 38 VYKAT XR vs 39 placebo 1:1 randomization in withdrawal study

Primary endpoint p-value P=0.0022 HQ-CT hyperphagia score change placebo vs VYKAT XR from baseline to week 16

Weight difference -1.6 kg (95% CI -3.1, -0.1) LS mean weight change placebo vs VYKAT XR over 16 weeks

BMI z-score difference -0.09 (95% CI -0.17, -0.01) LS mean BMI z-score change placebo vs VYKAT XR

Market Reality Check

$45.50 Last Close

Volume Volume 1,767,590 vs 20-day average 1,305,418 (relative volume 1.35). normal

Technical Shares at $47.17, trading below 200-day MA of $67.24 and well under 52-week high $90.32.

Peers on Argus

Peers showed mixed moves: IMVT +1.29%, RARE +3.33%, while MLYS -1.46%, SRRK -2.71%, VKTX -0.29%. No clear sector-wide alignment with SLNO.

Historical Context

Date	Event	Sentiment	Move	Catalyst
Dec 03	Board update	Negative	+3.9%	Announcement of long-serving board member’s passing and leadership transition.
Nov 24	Conference participation	Neutral	+1.8%	CEO presenting at a major healthcare investor conference webcast.
Nov 11	Share repurchase	Positive	+5.2%	$100M accelerated share repurchase signaling confidence post-profitability.
Nov 04	Earnings & launch	Positive	-2.7%	Profitable Q3 with strong VYKAT XR launch metrics and cash position.
Oct 28	Investor outreach	Neutral	+1.7%	Participation in several November investor conferences to engage shareholders.

Pattern Detected

Recent news has often been met with price moves in the same qualitative direction, though notable divergences occurred around earnings and a board member’s passing.

Recent Company History

This announcement adds to a series of catalysts for Soleno in late 2025. The company reported strong Q3 2025 results with product revenue of $66.0M, net income of $26.0M, and cash and securities of $556.1M as of Sept 30, 2025, following FDA approval and launch of VYKAT XR. An accelerated share repurchase of $100M and multiple conference appearances underscored commercial and investor-relations momentum. Today’s JCEM publication reinforces the clinical foundation behind VYKAT XR’s approval and commercialization in Prader-Willi syndrome.

Market Pulse Summary

This announcement highlights peer-reviewed publication of a pivotal randomized withdrawal study for VYKAT XR in Prader-Willi syndrome, reinforcing its efficacy and safety as the first FDA-approved treatment for hyperphagia in this population. The data include a significant HQ-CT result with P=0.0022 and favorable weight and BMI z-score differences with no serious adverse events on treatment. In context of prior profitability and commercial launch updates, investors may watch ongoing prescription trends and real-world safety data.

Key Terms

randomized withdrawal study medical

"details results from the 16-week randomized withdrawal study (C602-RWP) of VYKAT XR"

A randomized withdrawal study is a clinical trial where all participants initially receive the experimental treatment, and those who improve are then randomly assigned either to continue the treatment or to switch to an inactive pill or stop treatment so researchers can see whether benefits persist. Investors care because this design shows durability of effect and how quickly symptoms return after stopping, which affects regulatory decisions, prescribing guidance, patient demand and long-term sales — like removing a coach to see if performance holds up on its own.

phase 3 medical

"a key part of the comprehensive Phase 3 clinical program that established the efficacy"

Phase 3 is the late-stage clinical testing step for a new drug or medical treatment, where the product is given to large groups of patients to confirm effectiveness, monitor side effects, and compare it to standard care. Successful Phase 3 results are often the final scientific hurdle before regulators decide on approval and market launch—like passing a final exam before graduation—and can sharply change a company's valuation and future revenue prospects.

hyperphagia medical

"children and adults 4 years and older with hyperphagia in Prader-Willi syndrome (PWS)"

An abnormally strong, persistent urge to eat that leads to excessive food intake beyond normal hunger; it can be a symptom of neurological, hormonal, genetic, or psychiatric conditions. Investors care because therapies that reduce hyperphagia can become measurable drug trial endpoints, define patient populations and market size, and influence regulatory approval, reimbursement prospects and commercial potential in the obesity and rare-disease sectors.

prader-willi syndrome medical

"hyperphagia in Prader-Willi syndrome (PWS). The paper can be accessed"

A rare genetic disorder caused by missing or altered instructions on a specific chromosome that leads to constant hunger, low muscle tone, learning challenges, and hormonal problems; think of it as a faulty instruction manual that affects growth, appetite control, and development. Investors care because the condition creates a defined patient population, special regulatory incentives, and long-term medical needs that shape demand for therapies, diagnostics, and care services, influencing market size and risk for drug developers.

hyperphagia questionnaire for clinical trials (hq-ct) medical

"The primary endpoint was Hyperphagia Questionnaire for Clinical Trials (HQ-CT) total score"

A hyperphagia questionnaire for clinical trials (HQ‑CT) is a structured survey used in medical studies to measure the severity and frequency of excessive hunger and related eating behaviors. It gives researchers a consistent “ruler” to track whether a treatment reduces pathological appetite, and investors care because reliable measures of symptom improvement are key to proving a drug works, gaining regulatory approval, and forecasting commercial value.

clinical global impression of severity (cgi-s) medical

"Secondary endpoints included Clinical Global Impression of Severity (CGI-S) and Improvement"

Clinical Global Impression of Severity (CGI-S) is a clinician-rated, single-number assessment that describes how severe a patient’s illness appears at the time of evaluation, typically on a seven-point scale from ‘not ill’ to ‘extremely ill.’ Think of it as a quick medical “thermometer” for overall symptom burden. Investors watch CGI-S scores because they help show whether a treatment meaningfully reduces illness severity in clinical trials, which can influence trial success, regulatory decisions, and commercial prospects.

body mass index (bmi) z-score medical

"exploratory endpoints included weight and body mass index (BMI) z-score."

A BMI z-score is a standardized measure that shows how a child’s body mass index compares to a reference group of the same age and sex, expressed in how many standard deviations it is above or below the average. Think of it like a report card grade showing where a child stands compared with peers. For investors, changes in population BMI z-scores signal trends in child health that can affect demand for medical services, nutrition products, public-health programs, and related regulatory or reimbursement policies.

adverse events medical

"Adverse events were similar with both arms, with no serious adverse events"

Adverse events are any harmful or unwanted medical occurrences experienced by people using a drug, device, or undergoing a treatment, whether or not the problem is caused by the product. Think of them as complaints or breakdowns noticed during a trial or after a product is on the market; regulators record and investigate them. Investors care because clusters or serious adverse events can delay approvals, trigger costly studies or recalls, change labeling, and quickly alter a company’s revenue and risk profile.

AI-generated analysis. Not financial advice.

REDWOOD CITY, Calif., Jan. 05, 2026 (GLOBE NEWSWIRE) -- Soleno Therapeutics, Inc. (Soleno) (NASDAQ: SLNO), a biopharmaceutical company developing novel therapeutics for the treatment of rare diseases, today announced a publication in the peer-reviewed Journal of Clinical Endocrinology and Metabolism (JCEM). The paper, titled, “Diazoxide Choline Extended-Release Tablets in Prader-Willi Syndrome: A Randomized, Double-Blind, Placebo-Controlled, Withdrawal Period Study,” details results from the 16-week randomized withdrawal study (C602-RWP) of VYKAT™ XR (also known as diazoxide choline extended-release tablets, or DCCR) in children and adults 4 years and older with hyperphagia in Prader-Willi syndrome (PWS). The paper can be accessed online here.

The randomized withdrawal period study was a key part of the comprehensive Phase 3 clinical program that established the efficacy and safety of VYKAT XR and supported its approval by the U.S. Food and Drug Administration (FDA) as the first and only treatment for hyperphagia in people living with PWS. This clinical program included 127 participants with over 400 patient years of drug exposure, including individuals with nearly six years of continuous treatment.

“This important study provided additional controlled data confirming the safety and efficacy of VYKAT XR in people with PWS, and we are pleased that the positive results have been accepted for publication in JCEM, the world’s leading peer-reviewed journal focused on cutting-edge endocrine and metabolic research,” said Dr. Anish Bhatnagar, Chief Executive Officer and Chairman of the Board of Soleno Therapeutics. “Our strong momentum since commercial launch reflects both the significant unmet need that VYKAT XR addresses as the first FDA-approved treatment for the hallmark feature of PWS – hyperphagia – as well as the meaningful therapeutic benefit that it can offer to people living with this rare and complex genetic condition.”

Dr. Jennifer Miller, M.D., Professor of Pediatric Endocrinology at the University of Florida, Gainesville, and lead author of the paper, added, “The compelling results of the randomized withdrawal study highlighted in JCEM further reinforce the meaningful and sustained benefit of VYKAT XR in people living with hyperphagia caused by PWS. Notably, when study participants were transitioned to placebo during the randomized withdrawal study, we observed a significant worsening of hyperphagia, compared with those who remained on treatment with VYKAT XR. These results underscore the critical role that VYKAT XR can play in addressing hyperphagia, the most debilitating and distressing symptom of PWS, where no other effective therapeutic options are currently available.”

The 16-week, randomized withdrawal period study included 77 individuals who previously completed 13-week placebo-controlled and long-term open-label Phase 3 studies. Participants were randomized 1:1 to either VYKAT XR (n=38) or placebo (n=39). The primary endpoint was Hyperphagia Questionnaire for Clinical Trials (HQ-CT) total score change from baseline to week 16. Secondary endpoints included Clinical Global Impression of Severity (CGI-S) and Improvement (CGI-I); exploratory endpoints included weight and body mass index (BMI) z-score.

Key highlights from the publication:

• Hyperphagia worsened significantly when treatment with DCCR was withdrawn, compared to continued DCCR administration. Statistically significant increases (worsening) in HQ-CT from baseline to week 16 were observed with placebo versus DCCR (P=0.0022).
• CGI-S and CGI-I scores favored DCCR and approached, but did not reach, statistical significance.
• Consistent with the hyperphagia response, the placebo cohort gained more weight and increased their BMI z-score more than the DCCR cohort (LS mean weight difference (95% confidence interval) -1.6 kg (-3.1, -0.1); LS mean z-score difference -0.09 (-0.17, -0.01).
• Adverse events were similar with both arms, with no serious adverse events in the DCCR treatment arm. No participant experienced an adverse event leading to study drug discontinuation.

About PWS
Prader-Willi syndrome (PWS) is a rare genetic neurodevelopmental disorder caused by an abnormality in the gene expression on chromosome 15. The Prader-Willi Syndrome Association USA estimates that PWS occurs in one in every 15,000 live births. The defining symptom of PWS is hyperphagia, a chronic and life-threatening condition characterized by an intense persistent sensation of hunger accompanied by food preoccupations, an extreme drive to consume food, food-related behavior problems, and a lack of normal satiety, which can severely diminish the quality of life for individuals with PWS and their families. Hyperphagia can lead to significant mortality (e.g., stomach rupture, choking, accidental death due to food seeking behavior) and longer term, co-morbidities such as diabetes, obesity, and cardiovascular disease.

About VYKAT XR
VYKAT XR was approved by the U.S. Food and Drug Administration (FDA) on March 26, 2025, and is now commercially available to U.S. patients.

VYKAT XR is indicated for the treatment of hyperphagia in adults and pediatric patients 4 years of age and older with Prader-Willi syndrome (PWS).

IMPORTANT SAFETY INFORMATION

Contraindications
Use of VYKAT XR is contraindicated in patients who have a known hypersensitivity to diazoxide, other components of VYKAT XR, or to thiazides.

Warnings and Precautions

Hyperglycemia
Hyperglycemia, including diabetic ketoacidosis, has been reported. Before initiating VYKAT XR, test fasting plasma glucose (FPG) and HbA1c; optimize blood glucose in patients who have hyperglycemia. During treatment, regularly monitor fasting glucose (FPG or fasting blood glucose) and HbA1c. Monitor fasting glucose more frequently during the first few weeks of treatment in patients with risk factors for hyperglycemia.

Risk of Fluid Overload
Edema, including severe reactions associated with fluid overload, has been reported. Monitor for signs or symptoms of edema or fluid overload. VYKAT XR has not been studied in patients with compromised cardiac reserve and should be used with caution in these patients.

Adverse Reactions
The most common adverse reactions (incidence ≥10% and at least 2% greater than placebo) included hypertrichosis, edema, hyperglycemia, and rash.

Please see the full Prescribing Information, including Medication Guide.

About Soleno Therapeutics, Inc.
Soleno is focused on the development and commercialization of novel therapeutics for the treatment of rare diseases. The company’s first commercial product, VYKAT™ XR (diazoxide choline) extended-release tablets, formerly known as DCCR, is a once-daily oral treatment for hyperphagia in adults and children 4 years of age and older with Prader-Willi syndrome and was approved by the U.S. Food and Drug Administration (FDA) on March 26, 2025. For more information, please visit www.soleno.life.

Forward-Looking Statements
This press release contains forward-looking statements within the meaning of Section 21E of the Securities Exchange Act of 1934, as amended. All statements other than statements of historical facts contained in this press release are forward-looking statements. In some cases, you can identify forward-looking statements by terms such as "may," "will," "should," "expect," "plan," "anticipate," "could," "intend," "target," "project," "contemplates," "believes," "estimates," "predicts," "potential" or "continue" or the negative of these terms or other similar expressions. These forward-looking statements speak only as of the date of this press release and are subject to a number of risks, uncertainties and assumptions, including those described in the company's prior press releases and in the periodic reports it files with the SEC. The events and circumstances reflected in the company's forward-looking statements may not be achieved or occur and actual results could differ materially from those projected in the forward-looking statements. Except as required by applicable law, the company does not plan to publicly update or revise any forward-looking statements contained herein, whether as a result of any new information, future events, changed circumstances or otherwise.

Corporate Contact:
Brian Ritchie
LifeSci Advisors, LLC
212-915-2578

Media Contact:
media@soleno.life

FAQ

What did Soleno (SLNO) publish on January 5, 2026 about VYKAT XR?

Soleno published randomized withdrawal results for VYKAT XR in JCEM showing significant HQ-CT worsening after withdrawal (P=0.0022).

How large was the VYKAT XR randomized withdrawal study reported by SLNO?

The 16-week randomized withdrawal study included 77 participants (VYKAT XR n=38; placebo n=39).

What was the primary endpoint result for SLNO's VYKAT XR study?

Primary endpoint: change in HQ-CT; placebo showed significant worsening versus VYKAT XR with P=0.0022.

Did the VYKAT XR study show weight or BMI changes in SLNO's publication?

Yes. The placebo group gained more weight (LS mean difference -1.6 kg, 95% CI -3.1 to -0.1) and higher BMI z-score (-0.09, 95% CI -0.17 to -0.01).

Were there serious adverse events reported with VYKAT XR in the SLNO study?

No serious adverse events occurred in the VYKAT XR treatment arm, and no participants discontinued due to adverse events.

How does the JCEM publication affect Soleno (SLNO) investors?

The peer-reviewed randomized data and FDA approval strengthen clinical validation of VYKAT XR, but investors should note the study size and non-significant CGI endpoints.