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– 17 abstracts and presentations planned at SSIEM Symposium –

– Real-world evidence demonstrates significant diet liberalization achieved with Sephience while maintaining target blood Phe levels –

– Continued evidence of meaningful benefit across all patient subgroups –

, /PRNewswire/ -- PTC Therapeutics, Inc. (NASDAQ: PTCT) today announced that multiple Sephience™ (sepiapterin) scientific data presentations will be featured at the 2026 Society for the Study of Inborn Errors of Metabolism (SSIEM) Annual Symposium, taking place in Helsinki, Finland, from Aug. 25-28. The presentations include new data from clinical trials and real-world evidence which reinforce the clinically meaningful benefits of Sephience on lowering phenylalanine (Phe), significant diet liberalization and sustained metabolic control for the full spectrum of individuals living with phenylketonuria (PKU) including those with classical PKU. In addition, Sephience studies continue to show a consistent and favorable safety profile.

"The SSIEM presentations further demonstrate the broad clinical benefits of Sephience across the full spectrum of individuals living with PKU," said Matthew B. Klein, M.D., Chief Executive Officer. "In addition, new data to be presented at the PTC symposium show treatment with Sephience led to a large number of responsive participants achieving normalization of blood Phe levels (<120 µmol/L) in a rapid timeframe, including those with classical or non-BH4-responsive PKU. These impressive data support the potential benefits Sephience can deliver for individuals affected by PKU."

Highlights of the data to be presented at SSIEM 2026 include:

New analyses from the AMPLIPHY study demonstrate that Sephience treatment resulted in a 100% greater reduction in blood Phe for participants on sapropterin at screening after switching to Sephience. In an analysis of participants in Sephience studies with high baseline Phe levels (≥900 µmol/L), Sephience treatment resulted in clinically meaningful reductions in blood Phe levels within 14 days, with response rates comparable to the overall study population, and a safety profile consistent with prior studies. These findings support a trial of Sephience treatment in individuals with PKU regardless of severity or baseline Phe. An analysis of real-world data performed by a leading global key opinion leader shows that Sephience enabled significant dietary liberalization in adolescents, supporting greater independence, reduced dietary burden, and maintained metabolic control within recommended targets. These results were observed in individuals with both BH4-responsive and classical/non-BH4 responsive PKU mutations. About Sephience™ (sepiapterin)
Sephience™ is indicated for the treatment of adult and pediatric patients with phenylketonuria (PKU). Sephience is a natural precursor of the enzymatic co-factor BH4, a critical co-factor for phenylalanine hydroxylase (PAH). Through its unique dual mechanism of action, Sephience is able to effectively reduce blood phenylalanine (Phe) levels and has the potential to treat a broad range of PKU patients. Sephience is approved in the United States, the European Union/European Economic Area region, Japan and other countries.

Indication and Important Safety Information

Indication
SEPHIENCE is indicated for the treatment of hyperphenylalaninemia (HPA) in adult and pediatric patients 1 month of age and older with sepiapterin-responsive phenylketonuria (PKU). SEPHIENCE is to be used in conjunction with a phenylalanine (Phe)-restricted diet.

Contraindications
None.

Important Safety Information
Treatment with SEPHIENCE should be directed by physicians knowledgeable in the management of PKU. Biochemical response to SEPHIENCE can only be determined by a therapeutic trial with careful monitoring of ongoing dietary and nutritional balance to ensure adequate Phe control.

Warnings and Precautions

Increased Bleeding: SEPHIENCE may increase the risk of bleeding. Bleeding events, including superficial hematomas, prolonged bleeding, and heavy menstrual bleeding have occurred in patients treated with SEPHIENCE. Inform patients about the risk of bleeding associated with SEPHIENCE and have patients follow up with their healthcare provider should such a bleeding event occur. Consider treatment interruption with SEPHIENCE in patients with active bleeding. Hypophenylalaninemia: Some pediatric patients receiving SEPHIENCE experienced hypophenylalaninemia. Monitor blood Phe levels during treatment and modify the dosage of SEPHIENCE and/or dietary protein and Phe intake as needed to ensure adequate blood Phe level control. Frequent blood monitoring is recommended in the pediatric population. Interaction with Levodopa: In a 10-year post-marketing safety surveillance program for a non-PKU indication using another drug that is a phenylalanine hydroxylase (PAH) activator, three patients with underlying neurological disorders experienced seizures, exacerbation of seizures, over-stimulation, and irritability during co-administration with levodopa. Monitor patients who are receiving levodopa for changes in neurological status during treatment with SEPHIENCE. Adverse Reactions
Most common adverse reactions with SEPHIENCE (≥2% and > placebo) were diarrhea, headache, abdominal pain, hypophenylalaninemia, feces discoloration and oropharyngeal pain.

Drug Interactions
Avoid concomitant use of drugs known to inhibit folate synthesis dihydrofolate reductase (DHFR) (e.g., trimethoprim, methotrexate, trimetrexate, pemetrexed, pralatrexate, raltitrexed, and piritrexim) while taking SEPHIENCE. Concomitant administration of such drugs may reduce sepiapterin metabolism to BH4. If concomitant use is not avoidable, monitor blood Phe levels.

SEPHIENCE and PDE-5 inhibitors (e.g., sildenafil, vardenafil, or tadalafil) induce vasorelaxation and may reduce blood pressure. Monitor for signs and symptoms of hypotension.

For medical information, product complaints, or to report an adverse event, please call 1-866-562-4620 or email [email protected].

You may also report adverse events directly to FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

Please see Full Prescribing Information.

About Phenylketonuria
Phenylketonuria (PKU) is a rare, inherited metabolic disease, characterized by the body's inability to break down an essential amino acid called phenylalanine (Phe) and which can result in neurological and other symptoms. If left untreated or poorly managed, Phe can build up to harmful levels in the body. This causes severe and irreversible disabilities, such as permanent intellectual disability, seizures, delayed development, memory loss, and behavioral and emotional problems. Newborns with PKU initially do not have any symptoms, but symptoms are usually progressive, and damage caused by toxic levels of Phe in the first few years of life is irreversible. Diagnosis of PKU usually takes place during newborn screening programs. There are an estimated 58,000 people living with PKU globally.

About PTC Therapeutics, Inc.
PTC is a global biopharmaceutical company dedicated to the discovery, development and commercialization of clinically differentiated medicines for children and adults living with rare disorders. PTC is advancing a robust and diversified pipeline of transformative medicines as part of its mission to provide access to best-in-class treatments for patients with unmet medical needs. The company's strategy is to leverage its scientific expertise and global commercial infrastructure to optimize value for patients and other stakeholders. To learn more about PTC, please visit www.ptcbio.com and follow us on LinkedIn, X, Instagram and Facebook.

For More Information: 

Investors:
Ellen Cavaleri
+1 (615) 618-6228
[email protected] 

Media:
Jeanine Clemente
+1 (908) 912-9406
[email protected] 

Forward-Looking Statements: 
This press release contains forward-looking statements within the meaning of The Private Securities Litigation Reform Act of 1995. All statements contained in this release, other than statements of historic fact, are forward-looking statements, including statements regarding: the future expectations, plans and prospects for PTC, including with respect to the expected timing of clinical trials and studies, availability of data, regulatory submissions and responses, commercialization and other matters with respect to its products and product candidates; expectations with respect to Sephience; PTC's strategy, future operations, future financial position, future revenues, projected costs; and the objectives of management. Other forward-looking statements may be identified by the words, "guidance", "plan," "anticipate," "believe," "estimate," "expect," "intend," "may," "target," "potential," "will," "would," "could," "should," "continue," and similar expressions.

PTC's actual results, performance or achievements could differ materially from those expressed or implied by forward-looking statements it makes as a result of a variety of risks and uncertainties, including those related to: the outcome of pricing, coverage and reimbursement negotiations with third party payors for PTC's products or product candidates that PTC commercializes or may commercialize in the future; expectations with respect to Sephience, including commercialization and the potential achievement of sales milestones and contingent payments that PTC may be obligated to make; significant business effects, including the effects of industry, market, economic, political or regulatory conditions; changes in tax and other laws, regulations, rates and policies; the eligible patient base and commercial potential of PTC's products and product candidates; PTC's scientific approach and general development progress; and the factors discussed in the "Risk Factors" section of PTC's most recent Annual Report on Form 10-K, as well as any updates to these risk factors filed from time to time in PTC's other filings with the SEC. You are urged to carefully consider all such factors.

As with any pharmaceutical under development, there are significant risks in the development, regulatory approval, and commercialization of new products. There are no guarantees that any product will receive or maintain regulatory approval in any territory, or prove to be commercially successful, including Sephience.

The forward-looking statements contained herein represent PTC's views only as of the date of this press release and PTC does not undertake or plan to update or revise any such forward-looking statements to reflect actual results or changes in plans, prospects, assumptions, estimates or projections, or other circumstances occurring after the date of this press release except as required by law.

SOURCE PTC Therapeutics, Inc.

– Planned acquisition leverages existing regulatory and commercial infrastructure and leadership's experience in Fabry therapy commercialization –

– ST-920 is a one-time administered AAV gene therapy for the enzyme deficient in Fabry disease with demonstrated long-term clinical benefits and safety profile –

– BLA submission expected to be completed in Q4 2026 with potential for commercial launch in 2027 –

– PTC will host a conference call today, Aug. 12, at 5 p.m. ET –

, /PRNewswire/ -- PTC Therapeutics, Inc., (NASDAQ: PTCT) today announced that it was selected as the winning bidder to acquire ST-920 – a BLA-stage one-time administered AAV gene therapy for Fabry disease – from Sangamo Therapeutics in a competitive bankruptcy auction. The terms include $111 million upfront and up to $100 million in contingent milestone payments based on certain regulatory approvals. A rolling BLA submission to FDA for accelerated approval of ST-920 is expected to be completed in Q4 2026. The BLA is based on evidence of meaningful favorable clinical effect on renal function and safety and tolerability profile over 52 weeks in the Phase 1/2 STAAR study.

"This transaction advances our strategy of leveraging our accomplished existing rare disease global commercial infrastructure to accelerate short- and intermediate-term revenue growth," said Matthew B. Klein, M.D., Chief Executive Officer. "The ST-920 gene therapy program puts another innovative and valuable product in the demonstrated capable hands of our customer-facing teams. This was a unique opportunity with the potential for significant return on investment without the need for any development or commercial build and without impacting our objective of reaching cashflow break even in 2026. We look forward to working to bring ST-920 to all individuals who may benefit from this therapy as quickly as possible."

Fabry disease is a rare, inherited lysosomal storage disorder caused by mutations in the GLA gene, resulting in deficiency of the alpha-galactosidase A (α-Gal A) enzyme and causing a range of serious signs and symptoms that require lifelong treatments. It is estimated that there are 11,000 people living with Fabry disease in the United States with similar prevalence rates in markets where PTC has the potential to commercialize.

ST-920 is designed as a one-time administered AAV gene therapy that enables long-term production of the deficient α-Gal A enzyme and significant reduction in globotriaosylceramide (Gb3) levels with demonstrated durable clinical benefit and reduction of the burden associated with chronic Enzyme Replacement Therapy (ERT). ST-920 has received Regenerative Medicine Advanced Therapy (RMAT) designation as well as Orphan Drug and Fast Track designations from FDA.

The Phase 1/2 STAAR study demonstrated positive mean annualized estimated glomerular filtration rate (eGFR) slope at 52 weeks following ST-920 administration, as well as evidence of favorable effect on other aspects of Fabry disease including cardiac function and quality of life. The finding of improved eGFR over 52 weeks is differentiated from other Fabry therapies which demonstrated improved renal function but still negative eGFR slope from baseline. Furthermore, all study participants on ERT at study start were withdrawn from ERT. Durability of effect has been demonstrated with sustained increased α-Gal A activity maintained for up to 4.5 years for the earliest treated study participant, and evidence of maintained improvements in renal function across the study population. In addition, ST-920 has demonstrated an encouraging safety and tolerability profile and there is no requirement for routine prophylactic or post-infusion systemic immunosuppressive agents. 

The BLA submission for accelerated approval is based on the intermediate clinical endpoint of annualized eGFR at Week 52 as aligned with FDA, with 104-week results from the STAAR study planned to provide confirmatory evidence to support traditional approval. The nonclinical and clinical BLA modules have already been submitted as part of a rolling submission, with the CMC package expected to be submitted in Q4 2026. PTC will also pursue regulatory approval outside of the United States, again leveraging existing regulatory and commercial rare disease infrastructure.

The acquisition remains subject to definitive documentation, bankruptcy court approval, antitrust review, and other customary closing conditions. It is expected to close in late Q3 or early Q4 2026.

Conference Call and Webcast Details
PTC will hold a conference call today at 5 p.m. ET to discuss this news. To access the live webcast, please visit Events & Presentations within the Investors section of the PTC website. A replay of the webcast will be available on the PTC website for 30 days following the event. To participate via phone, please register in advance here to receive dial-in details.

About the STAAR Study
The Phase 1/2 STAAR study was a global open-label, single-dose, dose-ranging, multicenter clinical study designed to evaluate isaralgagene civaparvovec, or ST-920, a gene therapy product candidate in patients with Fabry disease. Isaralgagene civaparvovec requires a one-time infusion without preconditioning. The STAAR study enrolled patients who were on ERT, were ERT pseudo-naïve (defined as having been off ERT for six or more months), or who were ERT-naïve. The FDA has granted Orphan Drug, Fast Track, and RMAT designations to isaralgagene civaparvovec, which has also received Orphan Medicinal Product designation and PRIME eligibility from the European Medicines Agency and Innovative Licensing and Access Pathway from the U.K. Medicines and Healthcare products Regulatory Agency. 

About Fabry Disease
Fabry disease is a lysosomal storage disorder caused by mutations in the galactosidase alpha gene (GLA), which leads to deficient alpha-galactosidase A (α-Gal A) enzyme activity, which is necessary for metabolizing globotriaosylceramide (Gb3). The buildup of Gb3 in the cells can cause serious damage to vital organs, including the kidney, heart, nerves, eyes, gut and skin. Symptoms of Fabry disease can include decreased or absent sweat production, heat intolerance, angiokeratoma (skin blemishes), vision problems, kidney disease, heart failure, gastrointestinal disturbance, mood disorders, neuropathic pain and tingling in the extremities.

About PTC Therapeutics, Inc. 
PTC is a global biopharmaceutical company dedicated to the discovery, development and commercialization of clinically differentiated medicines for children and adults living with rare disorders. PTC is advancing a robust and diversified pipeline of transformative medicines as part of its mission to provide access to best-in-class treatments for patients with unmet medical needs. The company's strategy is to leverage its scientific expertise and global commercial infrastructure to optimize value for patients and other stakeholders. To learn more about PTC, please visit www.ptcbio.com and follow us on LinkedIn, X, Facebook and Instagram.

For more information please contact:

Investors:
Ellen Cavaleri
+1 (615) 618-8228
[email protected]

Media:
Jeanine Clemente
+1 (908) 912-9406
[email protected]

Forward-Looking Statements
This press release contains forward-looking statements within the meaning of The Private Securities Litigation Reform Act of 1995. All statements contained in this release, other than statements of historic fact, are forward-looking statements, including the Company's expectations regarding the proposed acquisition, including the expectation of finalizing definitive documentation for the transaction and the entry of an bankruptcy court order approving the transaction; the Company's ability to complete the acquisition; the anticipated benefits of ST-920; the timing of and potential for regulatory submissions and potential commercial launch for ST-920, if acquired; and PTC's strategy, future operations, future financial position, future revenues, projected costs; and the objectives of management. Other forward-looking statements may be identified by the words, "guidance," "plan," "anticipate," "believe," "estimate," "expect," "intend," "may," "target," "potential," "will," "would," "could," "should," "continue," "aim," and similar expressions.

PTC's actual results, performance or achievements could differ materially from those expressed or implied by forward-looking statements it makes as a result of a variety of risks and uncertainties, including those related to: uncertainty surrounding the bankruptcy's court entry of an order approving the acquisition and the possibility that the acquisition is not completed; the outcome of pricing, coverage and reimbursement negotiations with third party payors for PTC's products or product candidates that PTC commercializes or may commercialize in the future; expectations with respect to Sephience, including commercialization and the potential achievement of sales milestones and contingent payments that PTC may be obligated to make; PTC's ability to maintain its marketing authorization of Translarna for the treatment of nmDMD in geographies in which it has been approved and the effect of the European Commission's adoption of the negative opinion from the Committee for Medicinal Products for Human Use (CHMP) on Translarna and the withdrawal of the Translarna NDA in the US on other regulatory bodies; expectations with respect to PTC's license and collaboration agreement with Novartis Pharmaceuticals Corporation for votoplam for the treatment of Huntington's disease including its right to receive development, regulatory and sales milestones, profit sharing and royalty payments from Novartis, the design and expected timing of clinical trials and studies, the availability of data, and regulatory submissions and responses, including potential accelerated approval; expectations with respect to Upstaza/Kebilidi, including commercialization, manufacturing capabilities, and the potential achievement of sales milestones and contingent payments that PTC may be obligated to make; expectations with respect to vatiquinone, including with respect to the design and expected timing of clinical trials and studies, the availability of data, and regulatory submissions and responses and potential approvals and other matters; expectations with respect to the commercialization of Evrysdi under PTC's SMA collaboration; expectations with respect to the commercialization of Tegsedi and Waylivra; expectations regarding PTC's product candidates, including the timing of clinical trials and studies; significant business effects, including the effects of industry, market, economic, political or regulatory conditions; changes in tax and other laws, regulations, rates and policies; the eligible patient base and commercial potential of PTC's products and product candidates; PTC's scientific approach and general development progress; PTC's ability to satisfy its obligations under the terms of its lease agreements; the sufficiency of PTC's cash resources and its ability to obtain adequate financing in the future for its foreseeable and unforeseeable operating expenses and capital expenditures; and the factors discussed in the "Risk Factors" section of PTC's Annual Report on Form 10-K, as well as any updates to these risk factors filed from time to time in PTC's other filings with the SEC. You are urged to carefully consider all such factors.

The forward-looking statements contained herein represent PTC's views only as of the date of this press release and PTC does not undertake or plan to update or revise any such forward-looking statements to reflect actual results or changes in plans, prospects, assumptions, estimates or projections, or other circumstances occurring after the date of this press release except as required by law.

SOURCE PTC Therapeutics, Inc.

Neil Gregory Almstead, the chief technical ops officer of PTC Therapeutics, Inc. (PTCT 4.15%), sold 2,464 shares of common stock on July 9, 2026, at $90.25 per share, according to an SEC Form 4 filing.

Transaction summaryMetricValueTransaction value~$222,376Shares sold (direct)2,464Post-transaction shares (directly held)60,299Post-transaction shares (indirectly held)2,899Post-transaction value$5.66 millionTransaction value based on SEC Form 4 weighted average sale price ($90.25); post-transaction value based on July 09, 2026 market close ($89.55).

Key questionsWhat was the structural context of this disposal?
The transaction was part of a routine liquidity event conducted under a Rule 10b5-1 trading plan. The shares were sourced from an option grant issued on January 3, 2025, which is currently subject to a four-year vesting schedule. By utilizing a pre-established plan, the insider manages equity compensation in a manner that mitigates the potential for trading on material non-public information.How does this impact the insider’s total economic exposure?
While the sale involved 2,464 shares, Neil Gregory Almstead continues to hold a substantial interest in the company. In addition to the 63,198 shares of common stock held across direct and indirect accounts, the insider also holds 45,036 derivative securities, including vested and unvested awards, ensuring continued alignment with shareholder outcomes.What is the current operational and financial profile of the issuer?
PTC Therapeutics is a biopharmaceutical company focused on developing therapies for rare genetic disorders, maintaining a $7.0 billion market capitalization as of the July 10, 2026 market close. The firm reported trailing twelve-month revenue of $827.1 million and a net loss of $186.7 million, with an insider ownership base that represents 0.0762% of the company.Company OverviewMetricValueShare Price (as of market close 2026-07-10)$84.85Market Capitalization$7.0 billionRevenue (TTM)$827.1 millionNet Income (TTM)-$186.7 millionCompany SnapshotPTC Therapeutics develops and commercializes innovative therapies targeting rare genetic disorders, with a diversified portfolio of approved medications and experimental drug candidates across multiple stages of clinical development.The company generates revenue through the commercialization of approved therapeutic products while advancing a robust pipeline of novel drug candidates designed to address unmet medical needs in rare disease indications.PTC Therapeutics serves patients suffering from rare genetic disorders and their healthcare providers, focusing on therapeutic areas where there are significant unmet medical needs and limited treatment options.PTC Therapeutics is a biopharmaceutical enterprise with a market capitalization of $7 billion. The company has achieved TTM revenue of $827.1 million, demonstrating meaningful commercial traction in the rare disease therapeutics market. PTC's competitive differentiation lies in its specialized expertise in rare genetic diseases, coupled with a diversified pipeline spanning early-stage research through late-stage clinical development, positioning the company to capture significant value as pipeline candidates advance toward regulatory approval and commercialization.

What this transaction means for investorsWhen a technical-operations officer sells a stake this small on a schedule, there's simply nothing to decode. Almstead sold 2,464 shares under a preset plan, and they came straight off an option grant, so this is the routine way executives convert a sliver of vesting compensation into cash. He still holds 63,198 shares plus another 45,036 in options and awards, so the vast majority of his exposure is untouched.

Meanwhile, the company underneath is in the middle of a genuine commercial inflection. PTC posted first-quarter product revenue of $225.6 million, powered by its new PKU drug Sephience, which hit $124.6 million in sales, up 36% in a single quarter. Management raised full-year product guidance to between $750 million and $850 million, and CEO Matthew Klein pointed to sustained launch momentum in the U.S. and abroad. The company sits on roughly $1.89 billion in cash. For long-term investors, the real questions are whether Sephience's launch keeps compounding. More clarity on that front should be expected on July 29, when the firm reports fiscal 2026 third-quarter results.

Jonathan Ponciano has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.