hVIVO plc

("hVIVO", the "Company" or the "Group")

Influenza HCT contract signed with Traws Pharma

London, UK - 14 April 2026, hVIVO plc (AIM: HVO), a purpose-built, full-service international clinical development partner and the world leader in human challenge trials, announces that it has signed a Clinical Trial Agreement ("CTA") to conduct a human challenge (HCT) trial on behalf of Traws Pharma (NASDAQ: TRAW), a clinical-stage biopharmaceutical company developing novel therapies for respiratory viral diseases.  The trial will test Traws' prophylactic antiviral candidate, tivoxavir marboxil ("TXM"), using the hVIVO Influenza Human Challenge Study Model. TXM is an investigational oral, small molecule CAP-dependent endonuclease inhibitor designed to be administered as a single-dose for the treatment of seasonal influenza and bird flu.

The Phase 2a, randomised, double-blinded placebo-controlled trial is planned to take place at the Company's specialist state-of-the-art quarantine facilities in Canary Wharf. The study will evaluate TXM's safety, tolerability, and effectiveness in reducing the incidence and severity of influenza-induced illness in healthy adult participants. 

The study is expected to commence in H1 2026, with the majority of the revenue recognised in 2026. Approximately 150 healthy participants will be recruited through the Company's participant recruitment arm, FluCamp, and all lab work associated with the study will be conducted by hVIVO's own specialist virology laboratory in Canary Wharf.

Seasonal influenza causes significant morbidity and mortality each year, with an estimated 1 billion cases per year, 3-5 million severe cases and 290,000 - 650,000 deaths per year. To date, hVIVO has inoculated >5,000 healthy participants across 2,477 influenza, RSV and other viral HCTs, and has also helped accelerate the development of several antiviral and vaccine candidates for both Big Pharma and biotechnology clients through its consulting, laboratory and clinical trial services. This includes Cidara Therapeutics, Inc, which was acquired by Merck Sharp & Dohme LLC in January 2026, following a longstanding clinical development partnership across hVIVO's fully integrated early phase service offering.

Yamin 'Mo' Khan, Chief Executive Officer of hVIVO, said: "Through our Influenza Human Challenge Trial Model, we will be able to deliver fast, controlled, high-quality efficacy data for Traws Pharma that would not be achievable in traditional field studies, reducing development risk for TXM and improving capital efficiency. By leveraging key synergies across our integrated clinical development services and conducting participant recruitment all under one roof, this trial illustrates our unique value proposition as a true full-service clinical development partner."

Dr Andrew Catchpole, Chief Scientific Officer of hVIVO, added: "Influenza causes significant strain on global healthcare infrastructure each year and a new influenza pandemic continues to pose a worldwide threat, underlining the critical need for effective prophylactic antivirals. Our Influenza Human Challenge Study Model has been optimised by our expert team over decades, and our purpose-built, full-service offering is well placed to deliver an accelerated path to clinical proof-of-concept for TXM, and ultimately bring this and other important medicines to patients, faster."

Iain D. Dukes, Chief Executive Officer of Traws Pharma, commented: "This agreement represents an important step forward for Traws as we advance our programme and seek to generate high‑quality, efficacy clinical data efficiently. Partnering with hVIVO enables us to leverage a proven human challenge platform to support our development strategy and accelerate progress towards our next value‑inflection point."

Forward-Looking Statements:

Certain statements in this press release which are not historical facts are forward- looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, and are provided pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Any statements in this press release that are not statements of historical fact may be deemed forward-looking statements. Words such as "continue," "will," "may," "could," "should," "expect," "expected," "plans," "intend," "anticipate," "believe," "estimate," "predict," "potential," and similar expressions are intended to identify such forward-looking statements. These forward-looking statements include, but are not limited to, statements concerning whether this CTA and/or the HCT trial represents an important step forward for Traws Pharma in advancing its programme, whether this CTA  and/or the HCT trial will generate high‑quality, efficacy clinical data efficiently, whether Traws Pharma's partnering with hVIVO will enable Traws Pharma to leverage human challenge platform to support Traws Pharma's development strategy and whether this CTA and/or the HCT trial will accelerate progress towards Traws Pharma's next value‑inflection point. All forward-looking statements involve significant risks and uncertainties that could cause actual results to differ materially from those expressed or implied in the forward-looking statements, many of which are generally outside the control of Traws Pharma and/or hVIVO and are difficult to predict. Factors other than those referred to above could also cause Traws Pharma's and/or hVIVO's results to differ materially from expected results. Additional factors that could cause actual results to differ materially from those expressed or implied in the forward-looking statements can be found in Traws Pharma's filings with the Securities and Exchange Commission (the "SEC"), including its Annual Report on Form 10-K for the fiscal year ended December 31, 2024, its Quarterly Reports on Form 10-Q filed with the SEC during 2025 and 2026, as well as in its subsequent filings with the SEC. Traws Pharma anticipates that subsequent events and developments may cause its plans, intentions and expectations to change. Traws Pharma assumes no obligation, and it specifically disclaims any intention or obligation, to update any forward-looking statements, whether as a result of new information, future events or otherwise, except as expressly required by law. Forward-looking statements speak only as of the date they are made and should not be relied upon as representing Traws Pharma's plans and expectations as of any subsequent date. Additionally, the business and financial materials and any other statement or disclosure on, or made available through, Traws Pharma's website or other websites referenced or linked to this press release shall not be incorporated by reference into this press release.

For further information please contact:

Notes to Editors

hVIVO plc (AIM: HVO) is a purpose-built, full-service international clinical development partner and the global leader in human challenge trials, serving seven of the world's ten largest biopharma companies.

The Company has an end-to-end platform designed to bring important medicines to patients faster: spanning preclinical strategy, first‑in‑human studies, Phase II patient trials and specialist laboratory services, delivered through wholly owned sites and laboratories across the UK and Germany.

With a combined Group heritage of more than 100 years, hVIVO delivers an accelerated pathway to clinical proof-of-concept through four integrated service pillars: Consulting, Clinical Trials, Human Challenge Trials, and Laboratories.

·    Consulting provides expert-led pre-clinical and clinical strategy, encompassing non-clinical, clinical, CMC, pharmacokinetics, data management, biostatistics, and regulatory support to guide trial design, execution, and interpretation.

·    Clinical Trials offers Phase I/II CRO services, Phase II/III site services across the UK and Germany, and specialist recruitment through FluCamp, Europe's largest recruitment database.

·    Human Challenge Trials leverages hVIVO's state-of-the-art quarantine facility in London - the largest of its kind worldwide - to deliver fast, controlled, high-quality efficacy data through guaranteed viral exposure.

·    Laboratories provides cutting-edge virology and immunology laboratory services, including biobanking and sample storage, supporting both challenge trials and standalone client studies.