Fortress Biotech and Cyprium Therapeutics Announce U.S. FDA Approval of ZYCUBO® (copper histidinate), the First and Only Approved Treatment for Menkes Disease in the United States

Rhea-AI Summary

Fortress Biotech (Nasdaq: FBIO) and majority-owned Cyprium announced FDA approval of ZYCUBO® (copper histidinate) on January 13, 2026, as the first and only U.S. treatment for Menkes disease.

Key commercial terms: a Rare Pediatric Disease Priority Review Voucher will transfer to Cyprium, and Cyprium is eligible for tiered royalties plus up to $129 million in development and sales milestones from Sentynl. Clinical data showed a nearly 80% reduction in risk of death for early-treated patients and median overall survival of 177.1 months vs 17.6 months for the external control.

Positive

• First and only FDA-approved treatment for Menkes disease
• Cyprium to receive a transferred Rare Pediatric Disease PRV
• Eligibility for up to $129 million in milestones from Sentynl
• Nearly 80% reduction in mortality risk with early treatment
• Median OS 177.1 months (ZYCUBO ET) vs 17.6 months (EC)

Negative

• Common adverse reactions ≥7% include pneumonia, seizure, and infection
• Commercialization responsibility held by Sentynl, not Cyprium
• Milestone and royalty payments are contingent, not guaranteed

News Market Reaction – FBIO

-7.14% 4.6x vol

53 alerts

-7.14% News Effect

+4.5% Peak Tracked

-30.9% Trough Tracked

-$10M Valuation Impact

$130M Market Cap

4.6x Rel. Volume

On the day this news was published, FBIO declined 7.14%, reflecting a notable negative market reaction. Argus tracked a peak move of +4.5% during that session. Argus tracked a trough of -30.9% from its starting point during tracking. Our momentum scanner triggered 53 alerts that day, indicating high trading interest and price volatility. This price movement removed approximately $10M from the company's valuation, bringing the market cap to $130M at that time. Trading volume was very high at 4.6x the daily average, suggesting heavy selling pressure.

Data tracked by StockTitan Argus on the day of publication.

Key Figures

Milestone potential: $129 million Checkpoint sale upfront: $28 million Risk reduction in death: Nearly 80% reduction +5 more

8 metrics

Milestone potential $129 million Aggregate development and sales milestones from Sentynl to Cyprium

Checkpoint sale upfront $28 million Upfront payment to Fortress from Sun Pharma for Checkpoint Therapeutics

Risk reduction in death Nearly 80% reduction Risk of death vs untreated external control in Menkes patients

Median OS ZYCUBO cohort 177.1 months Early-treated Menkes disease subjects receiving ZYCUBO

Median OS control cohort 17.6 months Untreated contemporaneous external control Menkes cohort

Adverse reaction threshold Incidence ≥7% Cutoff for listing most common adverse reactions

FDA approvals cited 3 approvals in 15 months Emrosi, UNLOXCYT, and ZYCUBO referenced by management

PRV granted Rare Pediatric Disease PRV Priority Review Voucher issued at FDA approval of ZYCUBO

Market Reality Check

Price: $3.55 Vol: Volume 1,439,193 is 1.69x...

high vol

$3.55 Last Close

Volume Volume 1,439,193 is 1.69x the 20-day average of 853,326, indicating elevated trading activity ahead of this FDA approval. high

Technical Shares at $4.20 are trading above the 200-day MA of $2.43 and sit about 7% below the 52-week high of $4.53 while well above the 52-week low of $1.325.

Peers on Argus

Momentum scanner shows only one peer, ZNTL, moving with a -4.87% decline and no ...

1 Down

Momentum scanner shows only one peer, ZNTL, moving with a -4.87% decline and no news, while broader biotech peers display mixed moves (e.g., KALA up 3.23%, IOBT down 12.76%). This pattern points to stock-specific drivers rather than a coordinated sector move.

Historical Context

5 past events · Latest: Dec 15 (Positive)

Pattern 5 events

Date	Event	Sentiment	Move	Catalyst
Dec 15	Regulatory update	Positive	+13.3%	FDA accepted CUTX-101 NDA resubmission with new PDUFA action date.
Dec 10	Clinical data	Positive	+3.5%	Phase 1 Emrosi trial met microbiological endpoints with no safety issues.
Nov 14	Earnings update	Positive	+5.2%	Q3 2025 revenue growth and swing to profitability with higher cash.
Nov 12	Earnings update	Positive	-2.2%	Journey Medical Q3 revenue growth and improved margins, but shares fell.
Nov 05	Earnings notice	Neutral	+0.4%	Announcement of upcoming Q3 2025 results and conference call timing.

Pattern Detected

Recent positive regulatory and financial news has generally coincided with favorable price reactions, suggesting the stock often trades in line with constructive catalysts.

Recent Company History

Over the last several months, Fortress Biotech has reported improving fundamentals and steady regulatory progress. Q3 2025 results showed higher revenue and a swing to net income, helped by the sale of Checkpoint to Sun Pharma and stronger Journey Medical sales. On the Menkes program, the CUTX-101 NDA received a Complete Response Letter focused on manufacturing, followed by a resubmission and FDA acceptance with a new January 14, 2026 PDUFA date. Today’s ZYCUBO approval represents the anticipated regulatory resolution of that pathway and validates earlier survival data disclosed in prior updates.

Market Pulse Summary

The stock moved -7.1% in the session following this news. A negative reaction despite FDA approval o...

Analysis

The stock moved -7.1% in the session following this news. A negative reaction despite FDA approval of ZYCUBO would contrast with prior patterns, where regulatory and earnings catalysts often aligned with gains, including a 13.31% move on the NDA resubmission acceptance. Pressure could reflect profit-taking after a strong run from a $1.325 52-week low or concerns about economics of royalty and milestone structures. Broader biotech weakness and existing leverage under the Oaktree credit agreement might also weigh on sentiment around otherwise positive news.

Key Terms

rare pediatric disease priority review voucher, orphan drug designation, breakthrough therapy, fast track, +4 more

8 terms

rare pediatric disease priority review voucher regulatory

"Rare Pediatric Disease Priority Review Voucher (PRV) granted by FDA at approval"

A rare pediatric disease priority review voucher is a transferable regulatory benefit awarded to a company that wins approval for a drug treating a serious but uncommon childhood illness. It works like a “fast-pass” with regulators: the holder can use it to get an accelerated review of a future drug application or sell the voucher to another company, often for a large sum. Investors care because it can speed time to market or generate immediate cash, boosting potential returns and lowering risk on other programs.

orphan drug designation regulatory

"ZYCUBO has received Breakthrough Therapy, Fast Track, Rare Pediatric Disease, and Orphan Drug Designation"

Orphan drug designation is a special status given to medicines developed to treat rare diseases affecting only a small number of people. This status often provides benefits like faster approval processes and financial incentives, making it more attractive for companies to develop these drugs. For investors, it signals potential for exclusive market rights and reduced competition, which can impact the drug’s profitability.

breakthrough therapy regulatory

"ZYCUBO has received Breakthrough Therapy, Fast Track, Rare Pediatric Disease, and Orphan Drug Designation"

A breakthrough therapy is a regulatory designation granted to an experimental drug or treatment when early clinical evidence indicates it could offer a substantial improvement over existing options for a serious or life‑threatening condition. For investors it matters because the label brings faster, more intensive interaction with regulators and can shorten development and review time—like a VIP fast‑track toward potential approval, reducing time and risk before a product can reach the market.

fast track regulatory

"ZYCUBO has received Breakthrough Therapy, Fast Track, Rare Pediatric Disease, and Orphan Drug Designation"

A fast track designation is a regulatory label that speeds up the review and communication between a drug developer and regulators for treatments addressing serious illnesses or unmet medical needs. For investors, it matters because it can shorten development time and reduce regulatory delays—like getting a VIP lane at the airport—raising the chance of earlier market access and potential revenue, though it does not guarantee approval.

x-linked recessive medical

"Menkes disease is a rare X-linked recessive pediatric disease caused by mutations"

An X-linked recessive condition is a genetic trait carried on the X chromosome that typically causes symptoms in people with one X (usually males) but often only makes people with two Xs (usually females) carriers without clear symptoms. Think of the X chromosome as a shared blueprint: if the blueprint has a missing instruction, those with only one copy are affected while those with a backup copy often are not; for investors this affects patient counts, trial design, and market size for therapies targeting such disorders.

blood-brain barrier medical

"impaired copper transport across the blood-brain barrier, and, until now, there has been no approved treatment"

A protective barrier of tightly packed cells and supporting tissue that controls what substances in the blood can enter the brain, acting like a security checkpoint that keeps out most pathogens and many drugs while allowing essential nutrients through. For investors, the barrier matters because whether a therapy can cross or safely bypass it often determines clinical success, regulatory approval and commercial potential for treatments of brain disorders.

subcutaneous injectable medical

"ZYCUBO® is a subcutaneous injectable formulation of copper histidinate"

A subcutaneous injectable is a medicine formulated to be injected just under the skin into the fatty layer above muscle, typically with a syringe or an auto-injector (think insulin pens). For investors, this matters because such medicines are often easier for patients to self-administer at home, which can increase sales and reduce healthcare visits, but they also bring specific manufacturing, packaging and regulatory considerations that affect cost and marketability.

overall survival medical

"positive topline clinical efficacy results for ZYCUBO, demonstrating statistically significant improvement in overall survival"

Overall survival is the average or median length of time patients remain alive after starting a treatment or entering a clinical study, measured regardless of cause of death. Investors care because it is a clear, hard measure of a therapy’s real-world benefit — like timing how long a new battery actually runs — and strong improvements in overall survival can drive regulatory approval, market adoption and revenue potential.

AI-generated analysis. Not financial advice.

Rare Pediatric Disease Priority Review Voucher (PRV) granted by FDA at approval to be transferred from Sentynl Therapeutics to Cyprium

Cyprium eligible to receive tiered royalties and up to $129 million in aggregate development and sales milestones from Sentynl Therapeutics

MIAMI, Jan. 13, 2026 (GLOBE NEWSWIRE) -- Fortress Biotech, Inc. (Nasdaq: FBIO) (“Fortress”) and its majority-owned subsidiary, Cyprium Therapeutics, Inc. (“Cyprium”), today announced that the U.S. Food and Drug Administration (“FDA”) has approved ZYCUBO^® (copper histidinate, formerly known as CUTX-101) for the treatment of Menkes disease in pediatric patients.

In December 2023, Sentynl Therapeutics, Inc. (“Sentynl”), a U.S.-based biopharmaceutical company wholly-owned by Zydus Lifesciences Limited (“Zydus Group”), assumed full responsibility for the development and commercialization of CUTX-101 from Cyprium. A Rare Pediatric Disease Priority Review Voucher (PRV) was issued in connection with FDA approval and, pursuant to the transaction with Sentynl, will be transferred to Cyprium. Cyprium is also eligible to receive tiered royalties on net sales of ZYCUBO and up to $129 million in aggregate development and sales milestones from Sentynl.

Menkes disease is a rare X-linked recessive pediatric disease caused by mutations of the copper transporter ATP7A encoded by the ATP7A gene. Patients with Menkes disease are born with the inability to absorb dietary copper and subsequently have impaired copper transport across the blood-brain barrier, and, until now, there has been no approved treatment in the United States. ZYCUBO^® is a subcutaneous injectable formulation of copper histidinate that restores copper homeostasis and maintains copper levels in patients with Menkes disease.

“The approval of ZYCUBO is a pivotal milestone for our company and patients suffering from Menkes Disease, as it is the first and only FDA-approved treatment for this rare, often fatal, pediatric disease. In connection with FDA approval, ZYCUBO was granted a Rare Pediatric Disease Voucher which will be transferred from Sentynl to our majority-owned subsidiary Cyprium,” said Lindsay A. Rosenwald, M.D., Fortress’ Chairman, President and Chief Executive Officer and Cyprium’s Chairman. “With three FDA approvals received in the last 15 months, for Emrosi™, UNLOXCYT™ (cosibelimab-ipdl), and now ZYCUBO, along with the recent sale of Checkpoint Therapeutics to Sun Pharma for approximately $28 million upfront to Fortress, plus the potential for an additional contingent value right (CVR) payment and ongoing royalties on future sales of UNLOXCYT, we believe that our business model has demonstrated measurable success and continued execution across the portfolio. We look forward to the potential achievement of additional upcoming milestones across our extensive pipeline of commercial and clinical-stage assets.”

“The development and approval of ZYCUBO are the culmination of more than three decades of hard work and dedication by many people, including the team members at Cyprium, Fortress and Sentynl,” stated Lung S. Yam, M.D., Ph.D., Cyprium’s President and Chief Executive Officer. “We would like to express our gratitude to the Menkes disease patients and their families who participated in the clinical studies and helped advance our understanding of this devastating disease.”

The approval is supported by positive topline clinical efficacy results for ZYCUBO, demonstrating statistically significant improvement in overall survival for Menkes disease subjects who received early treatment (“ET”) with ZYCUBO, compared to an untreated contemporaneous external control (“EC”) cohort, with a nearly 80% reduction in the risk of death. Median overall survival (“OS”) was 177.1 months for ZYCUBO ET cohort compared to 17.6 months for the EC cohort.

The most common adverse reactions (incidence ≥7%) were pneumonia, viral infection, respiratory failure, seizure, bacterial infection, hemorrhage, hypotension, vomiting, tachycardia, pyrexia, volume depletion, fracture, dyspnea, transaminases elevation, diarrhea, fungal infection, anemia, and local administration reaction.

ZYCUBO has received Breakthrough Therapy, Fast Track, Rare Pediatric Disease, and Orphan Drug Designation from the FDA. Copper histidinate has also been granted Orphan Designation by the European Medicines Agency.

About Menkes Disease
Menkes disease is a rare X-linked recessive pediatric disease caused by gene mutations of the copper transporter ATP7A. The minimum birth prevalence for Menkes disease is believed to be 1 in 34,810 live male births, and potentially as high as 1 in 8,664 live male births, based on recent genome-based ascertainment. The condition is characterized by distinctive clinical features, including sparse and depigmented hair (“kinky hair”), connective tissue problems, and severe neurological symptoms such as seizures, hypotonia, failure to thrive, and neurodevelopmental delays. Mortality is high in untreated Menkes disease, with many patients dying between 2-3 years of age. Milder versions of ATP7A mutations are associated with conditions other than Menkes Disease, such as Occipital Horn Syndrome and ATP7A-related Distal Motor Neuropathy.

About ZYCUBO^® (copper histidinate)
ZYCUBO^® is the first and only FDA-approved, bioavailable copper replacement therapy for the treatment of Menkes disease, a copper transport deficiency caused by mutations in ATP7A. ZYCUBO is a subcutaneous injectable formulation of copper histidinate that is given daily to deliver elemental copper to the body. In a pooled analysis of two open label, single-arm clinical trials, early treatment with ZYCUBO (ZYCUBO-ET) demonstrated significant improvement in overall survival for Menkes disease patients with a nearly 80% reduction in the risk of death compared to the overall survival of patients in the untreated contemporaneous external control cohort. For more information, visit https://zycubo.com.

INDICATIONS AND USAGE

ZYCUBO is indicated for the treatment of Menkes disease in pediatric patients.

Limitations of Use

ZYCUBO is not indicated for the treatment of Occipital Horn Syndrome.

IMPORTANT SAFETY INFORMATION

Contraindications

None.

Warnings and Precautions

Copper Accumulation and Risk of Toxicity

Impaired copper transport in patients with Menkes disease can lead to copper accumulation and organ impairment in the kidneys, liver, and hematopoietic system. Treatment with ZYCUBO may lead to further copper accumulation and related toxicity, especially in the first two years of life given renal and hepatic immaturity.

Renal Dysfunction

Kidney injury has been reported in patients taking ZYCUBO. In patients with Menkes disease, kidney dysfunction may already be present from the accumulation of copper in the kidneys. This may be worsened from the administration of copper in ZYCUBO. The healthcare team will monitor your child's kidney function through periodic laboratory tests before and during ZYCUBO administration. The dose of ZYCUBO may be adjusted as appropriate based on the results of the laboratory tests.

Liver Dysfunction

Copper accumulation can result in liver dysfunction. The healthcare team will monitor your child's liver function through periodic laboratory tests before and during ZYCUBO administration. The dose of ZYCUBO may be adjusted as appropriate based on the results of the laboratory tests.

Hematological Abnormalities

Copper accumulation with ZYCUBO can result in spleen and bone marrow dysfunction as well as interference with iron metabolism. Anemia has been reported in patients taking ZYCUBO for Menkes disease. The healthcare team will perform periodic laboratory tests (complete blood count) before and during ZYCUBO administration. The dose of ZYCUBO may be adjusted as appropriate based on the results of the laboratory tests.

Adverse Reactions

The most common adverse reactions (>7%) were pneumonia (30%), viral infection (27%), respiratory failure¹ (23%) (including cardiopulmonary failure (9%)), seizure (23%), bacterial infection² (20%) (including renal and urinary tract infection (9%)), hemorrhage (18%), hypotension (16%), vomiting (15%), tachycardia (12%), pyrexia (12%), volume depletion (12%), fracture (12%), dyspnea (12%), transaminases elevation (10%), diarrhea (10%), fungal infection (9%), anemia (9%), and local administration reaction (7%).

Use in Specific Populations

Pregnancy

Risk Summary

There are no available data on ZYCUBO use during pregnancy to evaluate for a drug-associated risk of major birth defects, miscarriage, or other adverse maternal or fetal outcomes. Animal reproduction studies have not been conducted with ZYCUBO.

The background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defects, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2%-4% and 15%-20%, respectively.

Lactation

Risk Summary

There are no available data on the presence of ZYCUBO in either human or animal breast milk, the effects on the breastfed infant, or the effects on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for ZYCUBO and any potential adverse effects on the breastfed infant from ZYCUBO or from the underlying maternal condition.

Pediatric Use

The safety and effectiveness of ZYCUBO for the treatment of Menkes disease have been established in pediatric patients. Use of ZYCUBO for this indication is supported by evidence from two clinical trials. Data from patients in these two trials were compared to data from an untreated contemporaneous external control cohort.

Geriatric Use

Menkes disease is a disease of pediatric patients. Clinical trials of ZYCUBO did not include patients 65 years of age and older.

You are encouraged to report side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch, or call 1-800-FDA-1088.

Please see full U.S. Prescribing Information including Instructions for Use (IFU) for ZYCUBO^® at https://zycubo.com.

[1] Respiratory failure consists of multiple similar terms including cardiopulmonary failure.
[2] Bacterial infection consists of multiple similar terms including renal and urinary tract infection.

About Cyprium Therapeutics
Cyprium Therapeutics, Inc. (“Cyprium”) is focused on the development of novel therapies for the treatment of Menkes disease and related copper metabolism disorders. In March 2017, Cyprium entered into a Cooperative Research and Development Agreement with the Eunice Kennedy Shriver National Institute of Child Health and Human Development (“NICHD”), part of the NIH, to advance the clinical development of CUTX-101 (Copper Histidinate injection) for the treatment of Menkes disease. In 2023, Cyprium completed the transfer of its proprietary rights and assigned its FDA documents pertaining to CUTX-101 to Sentynl Therapeutics, Inc. ZYCUBO (formerly CUTX-101) was U.S. FDA-approved in 2026 to treat patients with Menkes disease. Cyprium and NICHD also have an ongoing worldwide, exclusive license agreement to develop and commercialize adeno-associated virus (AAV)-based gene therapy, called AAV-ATP7A, to deliver working copies of the copper transporter that is defective in patients with Menkes disease, and to be used in combination with CUTX-101; AAV-ATP7A gene therapy is currently in pre-clinical development and has received FDA Orphan Drug Designation. Cyprium was founded by, and is a majority-owned subsidiary of, Fortress Biotech, Inc. (Nasdaq: FBIO). For more information, visit www.cypriumtx.com.

About Fortress Biotech
Fortress Biotech, Inc. (“Fortress”) is an innovative biopharmaceutical company focused on acquiring and advancing assets to enhance long-term value for shareholders through product revenue, equity holdings and dividend and royalty income. The company has eight marketed prescription pharmaceutical products and multiple programs in development at Fortress, at its majority-owned and majority-controlled partners and subsidiaries and at partners and subsidiaries it founded and in which it holds significant minority ownership positions. Fortress’ portfolio is being commercialized and developed for various therapeutic areas including oncology, dermatology, and rare diseases. Fortress’ model is focused on leveraging its significant biopharmaceutical industry expertise and network to further expand and advance the company’s portfolio of product opportunities. Fortress has established partnerships with some of the world’s leading academic research institutions and biopharmaceutical companies to maximize each opportunity to its full potential, including AstraZeneca, City of Hope, Fred Hutchinson Cancer Center, Nationwide Children’s Hospital, Columbia University, Dana Farber Cancer Center and Sentynl Therapeutics. For more information, visit www.fortressbiotech.com.

Forward-Looking Statements
Statements in this press release that are not descriptions of historical facts are “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934, as amended. The words “anticipates,” “believes,” “can,” “continue,” “could,” “estimates,” “expects,” “intends,” “may,” “might,” “plans,” “potential,” “predicts,” “should,” or “will” or the negative of these terms or other comparable terminology are generally intended to identify forward-looking statements. These forward-looking statements are based on management’s current expectations and are subject to risks and uncertainties that could negatively affect our business, operating results, financial condition and stock price. Factors that could cause actual results to differ materially from those currently anticipated include risks relating to: the relatively small universe of potential buyers for a PRV; if we decide to sell the PRV and are able to find a buyer, the possibility that we are unable to do so on economic terms, or during a timeframe, that we deem favorable; our growth strategy, financing and strategic agreements and relationships; our need for substantial additional funds and uncertainties relating to financings; uncertainty related to the timing and amounts expected to be realized from future milestone, contingent value right, royalty or similar future revenue streams, if at all; our ability to identify, acquire, close and integrate product candidates successfully and on a timely basis; our ability to attract, integrate and retain key personnel; the early stage of products under development; the results of research and development activities; uncertainties relating to preclinical and clinical testing; our ability to obtain regulatory approval for products under development; our ability to successfully commercialize products or other marketable assets for which we receive regulatory approval; our ability to secure and maintain third-party manufacturing, marketing and distribution of our and our partner companies’ products and product candidates; government regulation; patent and intellectual property matters; competition; as well as other risks described in our SEC filings. We expressly disclaim any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein to reflect any change in our expectations or any changes in events, conditions or circumstances on which any such statement is based, except as may be required by law, and we claim the protection of the safe harbor for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995. The information contained herein is intended to be reviewed in its totality, and any stipulations, conditions or provisos that apply to a given piece of information in one part of this press release should be read as applying mutatis mutandis to every other instance of such information appearing herein.

Company Contact:
Jaclyn Jaffe
Fortress Biotech, Inc.
(781) 652-4500
ir@fortressbiotech.com

Media Relations Contact:
Tony Plohoros
6 Degrees
(908) 591-2839
tplohoros@6degreespr.com

FAQ

What did Fortress (FBIO) announce on January 13, 2026 about ZYCUBO?

Fortress and Cyprium announced FDA approval of ZYCUBO for Menkes disease and transfer of a Rare Pediatric Disease PRV to Cyprium.

How much can Cyprium receive from Sentynl related to ZYCUBO for FBIO shareholders?

Cyprium is eligible for tiered royalties and up to $129 million in aggregate development and sales milestones from Sentynl.

What were the key clinical results supporting ZYCUBO approval for FBIO?

Early-treated subjects had a nearly 80% lower risk of death; median OS was 177.1 months vs 17.6 months for the external control.

What are the most common side effects of ZYCUBO noted in the FDA approval?

Adverse reactions with incidence ≥7% included pneumonia, viral and bacterial infections, seizure, respiratory failure, and others.

Will Cyprium commercialize ZYCUBO directly for FBIO investors?

Sentynl assumed full development and commercialization responsibility and will transfer the PRV to Cyprium; Sentynl will manage commercialization.

What regulatory incentives did ZYCUBO receive relevant to FBIO?

ZYCUBO received Breakthrough Therapy, Fast Track, Rare Pediatric Disease, and Orphan Drug designations from the FDA.