PharmaTher’s Sairiyo Therapeutics to Explore PD-001, Its Patented Reformulated Cepharanthine, for Hantavirus

Independent research identified cepharanthine as a potential Hantavirus entry inhibitor, supporting further evaluation of Sairiyo’s patented, orally bioavailable PD-001 cepharanthine formulation for Hantavirus

TORONTO, ON — May 13, 2026 — PharmaTher Holdings Ltd. (CSE: PHRM) (OTCQB: PHRRF) (“PharmaTher” or the “Company”), a specialty pharmaceutical company, today announced that Sairiyo Therapeutics Inc. (“Sairiyo”), a company 49% owned by PharmaTher and 51% owned by PharmaDrug Inc. (CSE: PHRX) (OTC: LMLLF), is pursuing its strategic plans to focus on the clinical development of its patented enteric-coated oral Cepharanthine (“PD-001”) as a potential therapeutic candidate for Hantavirus (“HTNV”).

Independent published research has identified cepharanthine as a potential Hantavirus entry inhibitor. In the study titled Screening and identification of HTNVpv entry inhibitors with high-throughput pseudovirus-based chemiluminescence,1 researchers developed a high-throughput screening method using Hantaan virus pseudovirus (“HTNVpv”) and evaluated a library of 1,813 approved drugs and 556 small-molecule compounds. The study identified six compounds with anti-HTNVpv activity in the low-micromolar range, including cepharanthine. Among the selected compounds, cepharanthine not only demonstrated in vitro anti-HTNVpv activity but also inhibited HTNVpv-fluc infection in Balb/c mice. In that mouse model, cepharanthine inhibited Hantavirus pseudovirus infection 5 hours after infection by approximately 94% at 180 mg/kg/day, 93% at 90 mg/kg/day, and 92% at 45 mg/kg/day, with statistical significance reported at P < 0.01. The researchers also reported that time-of-addition analysis suggested cepharanthine may act during the viral entry and membrane fusion phases, which are important early steps in the hantavirus infection cycle. The authors concluded that cepharanthine may represent a candidate for further evaluation in hantavirus-related diseases, including HFRS and hantavirus cardiopulmonary syndrome.

Hantaan virus is an Old World hantavirus associated with hemorrhagic fever with renal syndrome (“HFRS”), a potentially severe disease affecting the kidneys and blood vessels. Hantaviruses remain a global public health concern because they are rodent-borne, can cause severe illness and death, and currently have limited treatment options. According to the World Health Organization, hantavirus infections can cause severe disease, HFRS occurs primarily in Europe and Asia, and there is no licensed specific antiviral treatment for hantavirus infection, with care currently focused on supportive management of respiratory, cardiac, and kidney complications.

“This independent research provides a reasonable scientific rationale to further evaluate Sairiyo’s PD-001 as a potential antiviral candidate for Hantavirus and other hantavirus-related diseases,” said Fabio Chianelli, CEO of PharmaTher. “The published findings suggest cepharanthine may interfere with early viral entry and membrane fusion, which are critical steps in the hantavirus infection cycle. PD-001 was specifically designed to address cepharanthine’s historical limitation of poor oral bioavailability through a patented enteric-coated oral formulation.”

Sairiyo has previously received approval from an Australian Human Research Ethics Committee to initiate a first-in-human Phase 1 clinical study of PD-001 for viral infectious diseases. The planned Phase 1 study is intended to evaluate the safety, tolerability, pharmacokinetics, and bioavailability profile of PD-001 in healthy volunteers and is not designed to establish therapeutic efficacy or demonstrate that PD-001 can treat, prevent, or cure any viral infectious disease, including Hantavirus or related hantavirus indications. Any future advancement of PD-001 into further clinical studies or indication-specific development would be subject to successful completion of Phase 1 activities, additional preclinical and/or clinical data, regulatory review, availability of financing, manufacturing readiness, and other development risks. PD-001 was previously the subject of a US$3.4 million contract from the Defense Threat Reduction Agency (“DTRA”) for Ebola virus-related research2; however, this prior contract should not be interpreted as government endorsement or validation of PD-001, nor does it establish efficacy, regulatory approval, commercial viability, or the likelihood of future development success in Ebola virus, Hantavirus, or any other infectious disease indication.

The Company would like to make it clear that is not making any express or implied claim that PD-001 or cepharanthine can treat, prevent, cure, or eliminate Hantavirus, HFRS, HCPS, or any other infectious disease at this time.

About PD-001 (Enteric-coated Oral Cepharanthine)

Cepharanthine is a natural product and an approved drug used for more than 70 years in Japan to successfully treat a variety of acute and chronic diseases. In clinical research, cepharanthine has been shown to exhibit multiple pharmacological properties including anti-oxidative, anti-inflammatory, immuno-regulatory, anti-cancer, anti-viral and anti-parasitic effects3,4. However, historically cepharanthine's low oral bioavailability has represented a major obstacle to realizing its full clinical potential.

Compared to generic cepharanthine, PD-001 has been shown in rodent and non-rodent models to possess markedly improved oral bioavailability (more easily absorbed). These findings support the development of an orally administered formulation, and in so doing, removes the undesirable requirement for frequent intravenous dosing to maintain therapeutic levels of drug in circulation. Sairiyo endeavours to develop an efficacious oral therapeutic to potentially improve outcomes for infectious disease and oncology applications.

PD-001 is protected by US Patent US10576077, with a patent expiration date of March 23, 2036.

About PharmaTher Holdings Ltd.

PharmaTher Holdings Ltd. (OTCQB: PHRRF; CSE: PHRM) is a specialty pharmaceutical company focused on developing, acquiring, and commercializing pharmaceutical products and enabling technologies. For more information, visit PharmaTher.com.

For more information about PharmaTher, please contact:

Fabio Chianelli
Chief Executive Officer
PharmaTher Holdings Ltd.
Tel: 1-888-846-3171
Email: info@pharmather.com
Website: www.pharmather.com

Neither the Canadian Securities Exchange nor its Regulation Services Provider accepts responsibility for the adequacy or accuracy of this release.

Forward-Looking Statements

This news release may contain forward-looking statements and information based on current expectations. These statements should not be read as guarantees of future performance or results of the Company. Forward looking statements in this press release relate to the potential for cepharanthine as a treatment for Hantaan Virus and the development of the Company's business. Such statements involve known and unknown risks, uncertainties and other factors that may cause actual results, performance or achievements to be materially different from those implied by such statements.

Forward-looking information is subject to known and unknown risks, uncertainties and other factors that may cause the actual results, level of activity, performance or achievements of the Company to be materially different from those expressed or implied by such forward-looking information. Such risks and other factors may include, but are not limited to: general business, economic, competitive, political and social uncertainties; general capital market conditions and market prices for securities; the actual results of the Company's future operations; competition; changes in legislation affecting the Company; the ability to obtain and maintain required permits and approvals, the timing and availability of external financing on acceptable terms; lack of qualified, skilled labour or loss of key individuals..

A description of additional risk factors that may cause actual results to differ materially from forward-looking information can be found in the Company’s disclosure documents on the SEDAR+ website at www.sedarplus.ca. Although the Company has attempted to identify important factors that could cause actual results to differ materially from those contained in forward-looking information, there may be other factors that cause results not to be as anticipated, estimated or intended. Accordingly, readers should not place undue reliance on forward-looking information. Readers are cautioned that the foregoing list of factors is not exhaustive. Readers are further cautioned not to place undue reliance on forward-looking information as there can be no assurance that the plans, intentions or expectations upon which they are placed will occur. Such information, although considered reasonable by management at the time of preparation, may prove to be incorrect and actual results may differ materially from those anticipated.

The Company's securities have not been registered under the U.S. Securities Act of 1933, as amended (the "U.S. Securities Act"), or applicable state securities laws, and may not be offered or sold to, or for the account or benefit of, persons in the United States or "U.S. Persons", as such term is defined in Regulations under the U.S. Securities Act, absent registration or an applicable exemption from such registration requirements. This press release shall not constitute an offer to sell or the solicitation of an offer to buy nor shall there be any sale of the securities in the United States or any jurisdiction in which such offer, solicitation or sale would be unlawful.

Forward-looking information contained in this press release is expressly qualified by this cautionary statement. The forward-looking information contained in this press release represents the expectations of the Company as of the date of this press release and, accordingly, are subject to change after such date. However, the Company expressly disclaims any intention or obligation to update or revise any forward-looking information, whether as a result of new information, future events or otherwise, except as expressly required by applicable securities law.

Sources:

1. Wen X, Zhang L, Liu Q, Xiao X, Huang W, Wang Y. Screening and identification of HTNVpv entry inhibitors with high-throughput pseudovirus-based chemiluminescence. Virol Sin. 2022 Aug;37(4):531-537. doi: 10.1016/j.virs.2022.04.015. Epub 2022 May 2. PMID: 35513270; PMCID: PMC9437608. (Link to paper)
2. https://www.swri.org/press-release/southwest-research-institute-texas-biomedical-research-institute-awarded-34-million
3. Saito T, Hikita M, Kohno K, Tanimura H, Miyahara M, Kobayashi M. Enhanced expression of the multidrug resistance gene in vindesine-resistant human esophageal cancer cells. Oncology. 1994 Sep-Oct;51(5):440-5. doi: 10.1159/000227380. PMID: 8052486.
4. Zhou P, Zhang R, Wang Y, Xu D, Zhang L, Qin J, Su G, Feng Y, Chen H, You S, Rui W, Liu H, Chen S, Chen H, Wang Y. Cepharanthine hydrochloride reverses the mdr1 (P-glycoprotein)-mediated esophageal squamous cell carcinoma cell cisplatin resistance through JNK and p53 signals. Oncotarget. 2017 Nov 27;8(67):111144-111160. doi: 10.18632/oncotarget.22676. Erratum in: Oncotarget. 2021 Jan 05;12(1):61-62. PMID: 29340044; PMCID: PMC5762312.