Theriva Biologics Announces U.S. FDA Guidance on Design of Phase 3 Study of VCN-01 for the Treatment of Metastatic Pancreatic Cancer Rockville, MD

Theriva Biologics Announces U.S. FDA

Guidance on Design of Phase 3 Study of VCN-01

for the Treatment of Metastatic Pancreatic Cancer

MD, December 5, 2024 - Theriva Biologics (NYSE American: TOVX), a diversified clinical-stage company

developing therapeutics designed to treat cancer and related diseases in areas of high unmet need, today

announced the outcomes of a recent Type D meeting with the U.S. Food and Drug Administration (FDA) to obtain guidance on the design

of a Phase 3 clinical study of lead clinical candidate VCN-01 in combination with standard-of-care chemotherapy for the treatment of

metastatic pancreatic adenocarcinoma (PDAC). The Company recently announced the

completion of target enrollment into the multinational VIRAGE Phase 2b clinical study evaluating intravenous VCN-01 in combination

with gemcitabine/nab-paclitaxel as a first line therapy for PDAC patients.

Type D meetings are focused on a narrow set of

issues that are used to discuss issues at key decision points to provide timely feedback critical to moving a drug development program

forward. The FDA advised that the on-going VIRAGE Phase 2b study should not be expanded into a Phase 3 study; rather, the optimal path

forward for the VCN-01 PDAC program is to conduct a stand-alone Phase 3 study of VCN-01 with gemcitabine/nab-paclitaxel. The FDA provided

general agreement with Theriva's proposed design for a Phase 3 clinical study and indicated that inclusion of additional standard-of-care

chemotherapy for PDAC was not necessary as it would complicate the study design and analysis. The FDA meeting also highlighted the FDA's

preferences regarding certain statistical elements of confirmatory clinical studies, including methods for sample size estimation and

the study population(s) used for data analysis.

"The FDA's advice on key elements

of a potential confirmatory Phase 3 study evaluating VCN-01 plus gemcitabine/nab-paclitaxel as a first-line treatment for metastatic PDAC

patients is critical as the VIRAGE study has entered final patient follow-up and we are actively planning the next steps in VCN-01 development,"

said Steven A. Shallcross, Chief Executive Officer of Theriva Biologics. "The feedback from the FDA and European regulatory agencies

will facilitate the design of a Phase 3 study protocol that is expected to maximize our ability to provide a new therapeutic option to

patients suffering this terrible disease."

An additional meeting with the FDA will be requested

after the completion of the VIRAGE study to discuss the details of the proposed confirmatory Phase 3 study protocol.

About Pancreatic Ductal Adenocarcinoma

Cancer of the pancreas consists of two main histological types: cancer

that arises from the ductal (exocrine) cells of the pancreas or, much less often, cancers may arise from the endocrine compartment of

the pancreas. Pancreatic ductal adenocarcinoma ("PDAC") accounts for more than 90% of all pancreatic tumors. It can be located

either in the head of the pancreas or in the body/tail. Pancreatic cancer usually metastasizes to the liver and peritoneum. Other less

common metastatic sites are the lungs, brain, kidney, and bone. In its early stages, pancreatic cancer does not typically result in any

characteristic symptoms. In many instances, progressive abdominal pain is the first symptom. Therefore, in most cases, pancreatic cancer

is diagnosed in its late stages (locally advanced non-metastatic or metastatic stage of the disease) when surgical resection and possibly

curative treatment is not possible. It is generally assumed that only 10% of cases are resectable at presentation, whereas 30-40% of patients

are diagnosed at local advanced/unresectable stage and 50-60% present with distant metastases.

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 142 patients to date in Company-

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.

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 is advancing 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. The Company's lead candidates are: (1) VCN-01, an oncolytic adenovirus designed

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

and immunosuppressive barrier to cancer treatment; (2) 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 (3) 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 the feedback from the FDA and European regulatory agencies facilitating the design of a Phase 3 study

protocol; the protocol maximizing the Company's ability to provide a new therapeutic option to patients suffering pancreatic cancer.

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

ability to effectively design the Phase 3 study protocol; the Company's and VCN's ability to reach clinical milestones when

anticipated, including the ability to continue to enroll patients as planned, generating positive clinical data that establishes VCN-01

may lead to improved clinical outcomes for patients with PDAC and other solid cancers; the Company's and VCN'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; 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 and VCN'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 and VCN's products, developments by competitors that render such products

obsolete or non-competitive, the Company's and VCN's ability to maintain license agreements, the continued maintenance and

growth of the Company's and VCN'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, 2023 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 by law.

For further information, please contact:

LifeSci Advisors, LLC

Source: Theriva Biologics, Inc.