April 26, 2021
SymBio Pharmaceuticals Limited
Fuminori Yoshida
Representative Director
President and Chief Executive Officer(Securities Code: 4582)

U.S. Food and Drug Administration granted fast track designation to antiviral agent
brincidofovir IV for the treatment of adenovirus infection in pediatric patientsTOKYO, Japan, April 26, 2021 -- SymBio Pharmaceuticals Limited (Headquarters: Tokyo, "SymBio")
today announced that it has received a fast track designation from the U.S. Food and Drug
Administration (FDA) for brincidofovir intravenous injection (“BCV IV”), an antiviral agent, for thetreatment of adenovirus infections ("AdV infection") in pediatric patients.
FDA's fast track designation is a process intended to expedite the review of new drugs that are
expected to be effective in treating serious or potentially life-threatening diseases and diseases withhigh unmet medical needs, with the goal of accelerating the process from development to review.
Receiving this designation provides more opportunities for consultation with FDA including clinical
trial consultations, and if clinical trials show efficacy and safety results, accelerated approval throughpriority reviews may be obtained.
SymBio will conduct the multinational Phase 2 clinical trial (Phase 2a) in the U.S. and the U.K. fordisseminated AdV infection and AdV infection in immunocompromised patients, an area with highunmet medical need as there currently exists no effective treatment. This study will confirm theappropriate dosage and administration for pediatric patients. The Company plans to conduct a global
study to be the next phase for approval applications.
BCV IV's broad antiviral activity against various double-stranded DNA viruses (Note) may be effectivein preventing and treating various viral infections in immunocompromised conditions, such as after
hematopoietic stem cell transplantation. Based on data on the efficacy and safety gained through theaforementioned study, we aim to expand the target area for multiviral infections after hematopoietic
stem cell transplantation (Note) and to maximize the benefit of BCV IV to patients by exploring thepossibility of expanding into organ transplantation, including kidney transplantation.
Statement from Mr. Fuminori Yoshida, President and Chief Executive Officer of SymBio: “AdVinfection in immunocompromised conditions such as those occurring after hematopoietic stem celltransplantation is an underserved therapeutic area with urgent need for a new treatment.
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We will proceed with a multinational clinical study for pediatric patients with AdV infection, an areawith extremely high unmet medical need. We expect that the FDA's fast track designation will
accelerate the review and our employees will work together to develop BCV IV so that it can bedelivered to patients as soon as possible.”
The Company does not expect the information presented herein to have any material impact on its
financial outlook for the fiscal year ending December 2021.
[Contact]
Investor Relations
Tel: +81 (0)3 5472 1125
*Hematopoietic stem cell transplantation and infection
Hematopoietic stem cell transplantation is a treatment for many hematologic cancers, such as
leukemia and malignant lymphoma that cannot be cured by anti-cancer drug treatment or radiation
therapy alone. It is used to transplant the hematopoietic stem cells that are donated or stored inadvance. Prior to hematopoietic stem cell transplantation, high doses of chemotherapy and total bodyirradiation can kill cancer cells, and at the same time the patient's own immunity is lost, so as not toreject new stem cells from the donor. Next, hematopoietic stem cell transplantation is performed byinfusion. It takes about 2 to 4 weeks for transplanted hematopoietic stem cells to produce blood in thepatient's bone marrow. Immune recovery after transplantation takes a long time, but the immune
system is severely compromised, especially immediately after transplantation, making the patient
susceptible to a variety of infections. If prophylaxis can be given, complications could be potentiallyreduced, leading to better prognosis. Various infectious diseases after hematopoietic stem celltransplantation are areas for which no effective therapy has been established, and in the medical
field, the treatment method which combines effectiveness and safety has been desired for many years.
** Double-stranded DNA (dsDNA) viruses
Double-stranded DNA (dsDNA) viruses includes Herpesviridae (e.g., CMV, HHV-6), adenoviridae(AdVs), polyomaviridae (e.g., BK virus and JC virus), papillomaviridae (HPVs), and poxviridae.
About Anti-viral Drug Brincidofovir
Brincidofovir (BCV) is a lipid-conjugate of cidofovir (an antiviral drug already approved and marketedin the U.S. and Europe, but unapproved in Japan; “CDV”). In addition to its antiviral effect, BCV wasintended to be designed to have improved safety profile as compared to CDV. Therefore, BCV is
expected to be an effective treatment for a wide range of DNA viruses (e.g., herpesviruses such ascytomegalovirus (CMV), adenovirus (AdV), BK virus, papillomavirus, etc.).
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Moreover, BCV is an easy-to-use and novel highly active antimultiviral agent that can reduce the riskof nephrotoxicity, which is a serious side effect of CDV.
SymBio entered into an exclusive global license agreement with Chimerix Inc. (Headquarters:Durham, NC, "Chimerix") for brincidofovir (BCV) on September 30, 2019. Under the terms of theagreement, Chimerix grants SymBio exclusive worldwide rights to develop, manufacture, andcommercialize BCV in all human indications, excluding the prevention and treatment of orthopox
infections (which includes smallpox and monkeypox).
SymBio aims to further globalize business, establish an integrated system for the supply of highquality pharmaceutical products, and grow as a specialty pharmaceutical company through theexclusive global license for BCV. To develop global operations, the Company is considering
partnerships that will utilize regional characteristics of the target diseases, and striving to maximize
the business value of the products and to deliver to patients who need our products as soon as
possible. The Company aims to serve the patients not only in Japan but also in Europe and the U.S.
market where the market size for organ transplantation is large, and Asia, including the Chinesemarket.
For further information, please see the SymBio’s press release dated October 1, 2019,https://www.symbiopharma.com/news/20191001.pdf
Innovativeness of Intravenous Brincidofovir (BCV)
Intravenous brincidofovir (BCV) is a lipid conjugate of cidofovir (CDV) with hexadecyloxypropyl(HDP), showing a rapid incorporation to the plasma membrane with enhanced uptake relative toCDV . Once inside target cells, the lipid chain is cleaved by action of intracellular phospholipases
releasing CDV, which is then converted to the active form, CDV diphosphate. As a result of increased
concentrations of CDV diphosphate into the cells, the antiviral activity of BCV is dramatically
improved compared with CDV. Furthermore, BCV can greatly reduce the risk of nephrotoxicity
associated with CDV because HDP conjugation greatly reduces plasma exposure to CDV andaccumulation of CDV in renal tubular epithelial cells through the transporter (OAT-1).

3About Chimerix
Chimerix is a development-stage biopharmaceutical company dedicated to accelerating theadvancement of innovative medicines that make a meaningful impact in the lives of patients livingwith cancer and other serious diseases. Its three most advanced clinical-stage development programs
are BCV, ONC201 and DSTAT. BCV is an antiviral drug candidate developed as a potential medical
countermeasure for smallpox and is currently under review for regulatory approval in the UnitedStates. ONC201 is currently in a registrational clinical program for recurrent H3 K27M-mutantglioma and a confirmatory response rate assessment is expected later this year. DSTAT is indevelopment as a potential first-line therapy in acute myeloid leukemia and as a potential treatment
for acute lung injury in hospitalized COVID-19 patients. For further information, please visit theChimerix website, www.chimerix.com.
About SymBio Pharmaceuticals Limited
SymBio Pharmaceuticals Limited was established in March, 2005 by Fuminori Yoshida who
previously served concurrently as Corporate VP of Amgen Inc. and founding President of AmgenJapan. In May, 2016 the Company incorporated its wholly-owned subsidiary in the U.S., called
SymBio Pharma USA, Inc. (Headquarters: Menlo Park, California, President: Mr. Fuminori Yoshida).
The Company’s underlying corporate mission is to “deliver hope to patients in need” as it aspires to bea leading global specialty biopharmaceutical company dedicated to addressing underserved medicalneeds.
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