Circio Holding

Circio Holding ASA (“Circio” or “the Company”) announced, on the 11^th of November 2026, a research collaboration with Nasdaq-listed Solid Biosciences Inc. (“Solid”) to combine Circio’s circVec expression platform with POLARIS-101, Solid’s proprietary next-generation AAV capsid, for systemic gene therapy in genetic heart disease. Under the agreement, Circio will generate constructs based on its latest generation 5 circVec design, which Solid will package using POLARIS-101 and its dual plasmid manufacturing platform. The parties will then jointly characterize and test the resulting vectors both in vitro and in vivo, with successful candidates evaluated further and advanced into preclinical development. No financial terms are disclosed.

Analyst Group’s View on the Solid Biosciences Collaboration

The collaboration addresses the same dose problem as Circio’s earlier capsid agreements, but with a counterparty of a different calibre. An AAV gene therapy consists of two parts: the capsid, the outer protein shell that carries the therapy through the bloodstream and determines which cells it enters, and the genetic cassette inside it, which instructs the cell to produce the therapeutic protein. The dose a patient requires therefore depends on how much of the injected vector reaches heart cells and how much protein each of those cells then produces. The heart is demanding on both counts, which is why systemic cardiac gene therapy requires very high doses, the central constraint in the field given that dose drives both toxicity risk and manufacturing cost. Each technology addresses one factor: POLARIS-101 is engineered to direct more of the vector to cardiac and skeletal muscle and less to the liver, while circVec acts once inside the cell, converting the genetic instructions into a circular RNA that resists degradation and therefore sustains protein production far longer than conventional linear RNA. Because the two act at different stages, their effects should in principle multiply rather than overlap, allowing the same protein level at a materially lower dose, which is what the in vitro and in vivo work is designed to establish.

What distinguishes this agreement from the capsid collaborations with AaviGen (May-26) and GenAssist (Jun-26) is clinical maturity. POLARIS-101 is the capsid used in Solid’s SGT-003 program in Duchenne muscular dystrophy, where 53 participants had been dosed in the Phase 1/2 INSPIRE DUCHENNE trial as of the 3rd of November 2026 with the candidate described by Solid as generally well tolerated, and dosing in the Phase 3 IMPACT DUCHENNE trial commenced during Q2-26. At an earlier data cut covering 41 participants dosed as of March 2026, Solid reported no evidence of drug-induced liver injury, myocarditis or thrombotic microangiopathy, the adverse event categories that have historically constrained high-dose systemic AAV programs, and the Company describes POLARIS-101 as the first systemically delivered, muscle- and cardiac-tropic next-generation capsid tested in the clinic. Circio’s previous capsid partners contribute preclinical assets; Solid contributes a delivery component with human exposure at scale, which removes a layer of uncertainty from the delivery side of the combined construct. The tolerability record is tied to a specific dose, payload and indication, however, and does not transfer automatically to a circVec-carrying vector in a cardiac indication, where expression levels and tissue distribution differ. What it does establish is that the capsid itself can be administered systemically in humans, which is the question Circio’s other delivery partnerships have yet to answer.

The timing is also notable. At ESGCT in October 2026, Circio presented a heart-optimised AAV9 design, circVec 5.2, reporting approximately 200-fold higher gene expression than conventional mRNA-based AAV9 alongside 95% heart-specific expression (25%) and off-target liver expression below 1% (9%). The collaboration draws on this same generation 5 architecture, meaning the Company enters the work with its strongest cardiac construct rather than an earlier-generation cassette. Analyst Group considers the pairing of a specificity-optimized expression cassette with a liver-de-targeted capsid to be directionally coherent, as both components push in the same direction on the heart-to-liver ratio that governs the safety margin in systemic cardiac gene therapy.

Moreover, the choice of partner carries a commercial dimension. Solid is not only a capsid developer but is building a cardiac gene therapy pipeline of its own, with preclinical-stage programs in an inherited arrhythmia disorder (SGT-501) and in an inherited form of dilated cardiomyopathy (SGT-601), a condition in which the heart muscle weakens and enlarges. A counterparty developing cardiac gene therapies itself has direct use for an expression technology that lowers the dose those therapies require, and Solid’s own cash position, USD 349m at the end of Q3-26, provides the means to act on a positive result. No licensing option, financial terms or exclusivity have been communicated and the agreement remains early-stage research, but Analyst Group considers a partner with its own cardiac ambitions to represent a more natural future licensing counterparty than a pure delivery-technology provider.

In summary, Analyst Group considers the Solid Biosciences agreement one of the most substantive additions to Circio’s delivery network to date. High vector doses remain the central bottleneck in systemic cardiac gene therapy, driving both toxicity risk and manufacturing cost, and the collaboration addresses that constraint from two directions. Here, circVec 5.2, which has shown approx. 200-fold higher gene expression than conventional AAV vectors in heart, raises output per cell, while POLARIS-101, a capsid already dosed systemically in patients, is engineered to direct more of the dose to cardiac muscle and less to the liver. The work nevertheless sits at an early stage, carries no disclosed financial terms, and positions any successful candidate at the entry to preclinical development rather than near the clinic. Analyst Group still considers the signal meaningful already today, as circVec has been chosen as the expression component by a clinical-stage developer with cardiac programs of its own, a counterparty profile from which a licensing relationship could realistically develop over time.

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About Solid Biosciences and POLARIS-101

Solid Biosciences is a Nasdaq-listed precision genetic medicine company developing gene therapies for rare neuromuscular and cardiac diseases. Its pipeline comprises SGT-003 in Duchenne muscular dystrophy, SGT-212 in Friedreich’s ataxia, SGT-501 in catecholaminergic polymorphic ventricular tachycardia and SGT-601 in TNNT2-mediated dilated cardiomyopathy, alongside a broader delivery platform of capsids, promoters and genetic regulators offered to external developers.

POLARIS-101, formerly designated AAV-SLB101, is Solid’s rationally engineered next-generation capsid, developed for enhanced skeletal and cardiac muscle tropism and reduced liver biodistribution. In preclinical work, Solid has reported faster transduction, improved muscle delivery and lower liver biodistribution relative to first-generation capsid benchmarks. Clinically, POLARIS-101 serves as the delivery capsid for SGT-003 in the Phase 1/2 INSPIRE DUCHENNE trial (NCT06138639) and the Phase 3 IMPACT DUCHENNE trial (NCT07160634). The capsid forms part of a wider platform that Solid markets to developers early in the research cycle, which is the route through which the Circio collaboration arises.