Theriva Biologics Announces Orphan Drug Designation Granted by the U.S. FDA for VCN-01 for the Treatment of Pancreatic Cancer Rockville, MD

Theriva Biologics Announces Orphan Drug Designation

Granted by the U.S. FDA for VCN-01 for the Treatment of Pancreatic Cancer

Rockville, MD, July 27, 2023 - Theriva Biologics (NYSE

American: TOVX), ("Theriva" or the "Company"), a clinical-stage company developing therapeutics designed to treat

cancer and related diseases in areas of high unmet need, today announced that the U.S. Food and Drug Administration (FDA) has granted

orphan drug designation to lead clinical candidate VCN-01, Theriva's systemic, selective, stroma-degrading oncolytic adenovirus

for the treatment of pancreatic cancer. In VIRAGE, the ongoing multinational Phase 2b clinical study, intravenous VCN-01 is being evaluated

in combination with standard-of-care (SoC) chemotherapy (gemcitabine/nab-paclitaxel) as a first line therapy for patients with pancreatic

ductal adenocarcinoma (PDAC). Previously, the FDA granted orphan drug designation to VCN-01 for treatment of retinoblastoma.

"The FDA's decision to grant orphan drug designation to

VCN-01 highlights the urgent need for new treatment options for patients with PDAC, which has one of the lowest survival rates among all

cancers," said Steven A. Shallcross, Chief Executive Officer of Theriva Biologics. "Efforts to improve upon the standard of

care treatment have largely stalled, despite the growing incidence of PDAC, and the need for novel therapies in this indication is acute.

The growing clinical data that underscore VCN-01's multiple modes of action and the compelling clinical outcomes observed in Phase

1 studies of VCN-01 in combination with chemotherapy or immunotherapy in patients with PDAC and other solid tumors, give us confidence

that VCN-01 has the potential to address this unmet medical need."

The FDA's Office of Orphan Products Development grants orphan

status to drugs being developed to treat, diagnose, or prevent a rare disease or condition affecting fewer than 200,000 people in the

United States. Orphan Drug Designation is designed to provide drug developers with various benefits to support the development of novel

drugs, including the potential for market exclusivity for seven years upon FDA approval, eligibility for tax credits for qualified clinical

trials, waiver of application fees, reduced annual product fees, clinical protocol assistance and potential qualification for expedited

development programs.

VCN-01 is a systemically administered oncolytic adenovirus designed

to selectively and aggressively replicate within tumor cells and degrade the tumor stroma that serves as a significant physical and immunosuppressive

barrier to cancer treatment. This unique mode-of-action enables VCN-01 to exert multiple antitumor effects by (i) selectively infecting

and lysing tumor cells; (ii) enhancing the access and perfusion of co-administered chemotherapy products; and (iii) increasing tumor immunogenicity

and exposing the tumor to the patient's immune system and co-administered immunotherapy products. Systemic administration enables

VCN-01 to exert its actions on both the primary tumor and metastases. VCN-01 has been administered to over 80 patients in Phase 1 and

investigator-sponsored clinical trials of different cancers, including PDAC (in combination with chemotherapy), head and neck squamous

cell carcinoma (with an immune checkpoint inhibitor), ovarian cancer (with CAR-T cell therapy), colorectal cancer, and retinoblastoma

(by intravitreal injection). More information on these clinical trials is available at Clinicaltrials.gov.

VIRAGE is a two-arm Phase 2b open-label, randomized, controlled, multicenter

clinical trial in patients with histologically confirmed, newly-diagnosed metastatic PDAC. VIRAGE is expected to enroll up to 92 adult

participants at up to 25 sites across the US and Europe. In both the control and treatment arms, patients will receive gemcitabine/nab-paclitaxel

standard of care chemotherapy over 28-day cycles. In the treatment arm only, patients will also receive systemically administered VCN-01

seven-days prior to the first and fourth cycles of gemcitabine/nab-paclitaxel treatment. Primary endpoints for the trial include overall

survival and VCN-01 safety/tolerability. Additional endpoints include progression free survival, objective response rate, and measures

of biodistribution, VCN-01 replication, and immune response. Since this is an open label trial, progress will be monitored very closely

and steps to accelerate the clinical program may be implemented if supported by the emerging data. More information about the trial is

available on Clinicaltrials.gov (NCT05673811), through the Spanish Clinical Trials Registry and European Union Drug Regulating Authorities

Clinical Trials Database (EudraCT Number: 2022-000897-24).

About Theriva Biologics, Inc.

Theriva Biologics (NYSE American: TOVX), is a diversified clinical-stage

company developing therapeutics designed to treat cancer and related diseases in areas of high unmet need. The Company's wholly-owned

Spanish subsidiary Theriva Biologics, S.L., has been developing a new oncolytic adenovirus platform designed for intravenous (IV), intravitreal

and antitumoral delivery to trigger tumor cell death, improve access of co-administered cancer therapies to the tumor, and promote a

robust and sustained anti-tumor response by the patient's immune system. In addition to VCN-01, the Company's clinical-stage

candidates include (1) SYN-004 (ribaxamase) which is designed to degrade certain commonly used IV beta-lactam antibiotics within the

gastrointestinal (GI) tract to prevent microbiome damage, thereby limiting overgrowth of pathogenic organisms such as VRE (vancomycin

resistant Enterococci) and reducing the incidence and severity of acute graft-versus-host-disease (aGVHD) in allogeneic hematopoietic

cell transplant (HCT) recipients); and (2) SYN-020, a recombinant oral formulation of the enzyme intestinal alkaline phosphatase (IAP)

produced under cGMP conditions and intended to treat both local GI and systemic diseases. For more information, please visit Theriva

Biologics' website at www.therivabio.com.

Forward-Looking Statement

This release contains forward-looking statements within the

meaning of the Private Securities Litigation Reform Act of 1995. In some cases forward-looking statements can be identified by

terminology such as "may," "should," "potential," "continue," "expects,"

"anticipates," "intends," "plans," "believes," "estimates," and similar

expressions, and include statements regarding VCN-01's potential to address the unmet medical need for treatments for PDAC,

the potential benefits of orphan drug designation including the potential for market exclusivity for seven years upon FDA approval,

eligibility for tax credits for qualified clinical trials, waiver of application fees, reduced annual product fees, clinical

protocol assistance and potential qualification for expedited development, expected to enrollment of the Virage of up to 92 adult

participants at up to 25 sites across the US and Europe. These

forward-looking statements are based on management's expectations and assumptions as of the date of this press release and are

subject to a number of risks and uncertainties, many of which are difficult to predict that could cause actual results to differ

materially from current expectations and assumptions from those set forth or implied by any forward-looking statements. Important

factors that could cause actual results to differ materially from current expectations include, among others, the Company's

ability to address the unmet medical needs for treatment of PDAC, the Company's ability to take advantage of the potential

benefits of orphan drug designation, the Company's ability to reach clinical milestones when anticipated, the Company's

ability to successfully operate the combined US and Spanish business entities , the Company's product candidates demonstrating

safety and effectiveness, as well as results that are consistent with prior results; the ability to complete clinical trials on time

and achieve the desired results and benefits, continuing clinical trial enrollment as expected; the ability to obtain regulatory

approval for commercialization of product candidates or to comply with ongoing regulatory requirements, regulatory limitations

relating to the Company's ability to promote or commercialize their product candidates for the specific indications,

acceptance of product candidates in the marketplace and the successful development, marketing or sale of the Company's

products, developments by competitors that render such products obsolete or non-competitive, the Company's ability to maintain

license agreements, the continued maintenance and growth of the Company's patent estate, the ability to continue to remain

well financed and other factors described in the Company's Annual Report on Form 10-K for the year ended December 31, 2022 and

its other filings with the SEC, including subsequent periodic reports on Forms 10-Q and current reports on Form 8-K. The information

in this release is provided only as of the date of this release, and Theriva Biologics undertakes no obligation to update any

forward-looking statements contained in this release on account of new information, future events, or otherwise, except as required

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