Form 8-K

8-K — Theriva Biologics, Inc.

Accession: 0001104659-26-044906

Filed: 2026-04-17

Period: 2026-04-17

CIK: 0000894158

SIC: 2834 (PHARMACEUTICAL PREPARATIONS)

Item: Regulation FD Disclosure

Item: Other Events

Item: Financial Statements and Exhibits

Documents

8-K — tm2612012d1_8k.htm (Primary)

EX-99.1 — EXHIBIT 99.1 (tm2612012d1_ex99-1.htm)

EX-99.2 — EXHIBIT 99.2 (tm2612012d1_ex99-2.htm)

GRAPHIC (tm2612012d1_ex99-1img001.jpg)

GRAPHIC (tm2612012d1_ex99-2img001.jpg)

XML — IDEA: XBRL DOCUMENT (R1.htm)

8-K — FORM 8-K

8-K (Primary)

Filename: tm2612012d1_8k.htm · Sequence: 1

false

0000894158

2026-04-17

iso4217:USD

xbrli:shares

iso4217:USD

xbrli:shares

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event

reported): April 17, 2026

THERIVA BIOLOGICS, INC.

(Exact name of registrant as specified in its charter)

Nevada

001-12584

13-3808303

(State or other jurisdiction of

incorporation)

(Commission File No.)

(IRS Employer Identification

No.)

9605 Medical Center Drive, Suite 270

Rockville, Maryland 20850

(Address of principal executive offices and zip

code)

(301) 417-4364

Registrant’s telephone number, including

area code

N/A

(Former name or former address, if changed since

last report)

Check the appropriate box below if the Form 8-K

filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General

Instruction A.2. below):

Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

Soliciting material pursuant to Rule 14a-12(b) under the Exchange Act (17 CFR 240.14a-12)

Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b)

of the Act:

Title of each class

Trading Symbol(s)

Name

of each exchange on which

registered

Common stock, par value $0.001 per share

TOVX

NYSE American

Indicate by check mark whether the registrant

is an emerging growth company as defined in in Rule 405 of the Securities Act of 1933 (17 CFR §230.405 of this chapter) or Rule 12b-2

of the Securities Exchange Act of 1934 (17 CFR §240.12b-2 of this chapter).

Emerging growth company ¨

If an emerging growth company, indicate by checkmark

if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards

provided pursuant to Section 13(a) of the Exchange Act. ¨

Item 7.01. Regulation FD Disclosure.

On April 17, 2026, Theriva

Biologics, Inc. (the “Company”) issued a press release announcing an upcoming poster presentation of new data and subgroup

analyses from the VIRAGE Phase 2b clinical trial evaluating VCN-01 (zabilugene almadenorepvec) plus gemcitabine/nab-paclitaxel in newly-diagnosed

metastatic pancreatic cancer patients at the American Association for Cancer Research (AACR) Annual Meeting to be held in San Diego, CA

from 17-22 April 2026.

· Presenting author: Dr. Manuel Hidalgo, NYU Langone Health Perlmutter Cancer Center, New York, NY

· Title: Analysis of tumor and biomarker responses in the VIRAGE Trial, a randomized Phase IIb, open-label,

study of nab-paclitaxel and gemcitabine with/without intravenous VCN-01 in patients with metastatic pancreatic cancer (mPDAC)

· Poster #: CT162

· Date and time: Monday April 20, 2026, 2:00-5:00 PM US PDT

· Session: PO.CT01.05 - Phase II and Phase III Clinical Trials

· Location: San Diego Convention Center, Hall B, Section 52, Board 26.

The information in this

Item 7.01 and in the press release furnished as Exhibit 99.1 to this Current Report on Form 8-K shall not be deemed to be “filed”

for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that section

or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended and shall not be incorporated by reference into any filing with

the U.S. Securities and Exchange Commission made by the Company, whether made before or after the date hereof, regardless of any general

incorporation language in such filing. The press release furnished as Exhibit 99.1 to this Current Report on Form 8-K includes “safe

harbor” language pursuant to the Private Securities Litigation Reform Act of 1995, as amended, indicating that certain statements

contained therein are “forward-looking” rather than historical.

Item 8.01. Other Events.

On April 17, 2026, the Company issued a press

release announcing an upcoming poster presentation of new data and subgroup analyses from the VIRAGE Phase 2b clinical trial evaluating

VCN-01 (zabilugene almadenorepvec) plus gemcitabine/nab-paclitaxel in newly-diagnosed metastatic pancreatic cancer patients at the American

Association for Cancer Research (AACR) Annual Meeting to be held in San Diego, CA from 17-22 April 2026.

Details of the poster

presentation are below:

· Presenting author: Dr. Manuel Hidalgo, NYU Langone Health Perlmutter Cancer Center, New York, NY

· Title: Analysis of tumor and biomarker responses in the VIRAGE Trial, a randomized Phase IIb, open-label,

study of nab-paclitaxel and gemcitabine with/without intravenous VCN-01 in patients with metastatic pancreatic cancer (mPDAC)

· Poster #: CT162

· Date and time: Monday April 20, 2026, 2:00-5:00 PM US PDT

· Session: PO.CT01.05 - Phase II and Phase III Clinical Trials

· Location: San Diego Convention Center, Hall B, Section 52, Board 26.

Included in the poster

presentation are the conclusions set forth below.

· Patients receiving VCN-01 + gemcitabine/nab-paclitaxel (“GnP”) had improved overall survival and progressive free survival

compared to GnP alone. The late separation of survival curves may reflect an immune-mediated mechanism of action.

· Treatment with VCN-01 + GnP resulted in later-emerging, higher magnitude, and more durable responses than GnP alone.

· The OS benefit of VCN-01 + GnP was generally maintained across subgroups including liver metastases, despite a post-recruitment imbalance.

· Patients receiving a second administration of VCN-01 revealed a greater benefit in OS and PFS.

The full poster for the

presentation has been released by the American Association for Cancer Research. A copy of the poster presentation titled Analysis of tumor

and biomarker responses in the VIRAGE Trial, a randomized Phase IIb, open-label, study of nab-paclitaxel and gemcitabine with/without

intravenous VCN-01 in patients with metastatic pancreatic cancer (mPDAC)is filed as exhibit 99.2 to this Current Report on Form 8-K. and

is incorporated herein by reference.

Item 9.01. Financial Statements and Exhibits.

(d)

Exhibits.

The following exhibit is furnished with this Current Report on Form 8-K.

Exhibit

Number

Description

99.1

Press Release issued by Theriva Biologics, Inc., dated April 17, 2026

99.2

Poster Presentation titled “Analysis of tumor and biomarker responses in the VIRAGE Trial, a randomized Phase IIb, open-label, study of nab-paclitaxel and gemcitabine with/without intravenous VCN-01 in patients with metastatic pancreatic cancer (mPDAC)”

104

Cover Page Interactive Data File (embedded within the XBRL document)

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf

by the undersigned hereunto duly authorized.

Dated: April 17, 2026

THERIVA

BIOLOGICS, INC.

By:

/s/ Steven A. Shallcross

Name:

Steven A. Shallcross

Title:

Chief Executive Officer

and Chief Financial Officer

EX-99.1 — EXHIBIT 99.1

EX-99.1

Filename: tm2612012d1_ex99-1.htm · Sequence: 2

Exhibit 99.1

Theriva™ Biologics Announces Upcoming

Presentation of Additional Data from the VIRAGE Phase 2b Clinical Trial of VCN-01 in Metastatic Pancreatic Cancer at AACR 2026 Annual

Meeting

- Tumor reponse, biomarker, and subgroup analyses

from the VIRAGE Phase 2b clinical trial support a VCN-01 immune-mediated mode of action and demonstrate improved outcomes in VCN-01 treated

patients across multiple subgroups, including patients with liver metastases -

- Data to be presented in a poster session at

the American Association of Cancer Research (AACR) Annual Meeting in San Diego, California on Monday April 20, 2026-

Rockville,

MD, April 17, 2026 – Theriva™ Biologics (NYSE American: TOVX), (“Theriva” or the “Company”),

a diversified clinical-stage company developing therapeutics designed to treat cancer and related diseases in areas of high unmet need,

today announced an upcoming poster presentation of new data and subgroup analyses from the VIRAGE Phase 2b clinical trial evaluating VCN-01

(zabilugene almadenorepvec) plus gemcitabine/nab-paclitaxel in newly-diagnosed metastatic pancreatic cancer patients. Tumor reponse, biomarker

data, and subgroup analyses are to be presented at the American Association for Cancer Research (AACR) Annual Meeting to be held in San

Diego, CA from 17-22 April 2026.

Details of the poster presentation are below:

· Presenting author: Dr. Manuel Hidalgo, NYU Langone Health Perlmutter Cancer Center, New York, NY

· Title: Analysis of tumor and biomarker responses in the VIRAGE Trial, a randomized Phase IIb, open-label, study of nab-paclitaxel

and gemcitabine with/without intravenous VCN-01 in patients with metastatic pancreatic cancer (mPDAC)

· Poster #: CT162

· Date and time: Monday April 20, 2026, 2:00-5:00 PM US PDT

· Session: PO.CT01.05 - Phase II and Phase III Clinical Trials

· Location: San Diego Convention Center, Hall B, Section 52, Board 26.

“The

new data and analyses to be presented at the AACR meeting further reinforce our confidence in the clinical potential of VCN-01 plus gemcitabine/nab-paclitaxel

chemotherapy to help metastatic PDAC patients,” said Steven A. Shallcross, Chief Executive Officer of Theriva Biologics. “Taken

together, the tumor response and biomarker data support an immune-mediated mode of action for VCN-01, which is consistent with the previously

reported clinical observations, showing that patients treated with VCN-01 plus gemcitabine/nab-paclitaxel

experienced a significantly protracted duration of response concomitant with a later-stage prolongation of survival compared to patients

treated with gemcitabine/nab-paclitaxel alone. We have achieved alignment with both the FDA and the EMA on a proposed pivotal Phase 3

clinical trial to evaluate multiple doses of VCN-01 plus gemcitabine/nab-paclitaxel in first-line metastatic PDAC patients, and we are

planning a small study to assess whether more frequent and extended VCN-01 dosing could further improve outcomes.”

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.

About VCN-01

VCN-01 (zabilugene almadenorepvec) 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 clinical trials of different cancers, including pancreatic ductal adenocarcinoma (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’s 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. The Company’s

lead clinical-stage candidates is VCN-01 (zabilugene almadenorepvec), 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. An exploratory clinical trial is also on-going with 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. 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 Company’s confidence in the clinical potential

of VCN-01 plus gemcitabine/nab-paclitaxel chemotherapy to help metastatic PDAC patients; tumor response and biomarker data supporting

an immune-mediated mode of action for VCN-01; alignment with the FDA and EMA on a proposed Phase 3 clinical trial evaluating multiple

doses of VCN-01 plus gemcitabine/nab-paclitaxel in first-line metastatic PDAC patients; and planning a small study to assess whether

more frequent and extended VCN-01 dosing could further improve outcomes. Important factors that could cause actual results to differ materially

from current expectations include, among others, the Company’s ability to finalize the proposed pivotal Phase 3 study protocol and

file a BLA; the Company’s ability to obtain development funding and/or partnerships; the Company’s ability to reach clinical

milestones when anticipated, including the ability to continue to enroll patients as planned; generating clinical data that establishes

VCN-01 may improve patient outcomes in metastatic PDAC patients; the ability to obtain regulatory approval for commercialization of product

candidates or to comply with ongoing regulatory requirements, including approval of VCN-01 to treat patients with PDAC; regulatory limitations

relating to the Company’s ability to promote or commercialize their product candidates for the specific indications; acceptance

of the Company’s product candidates in the marketplace; 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, 2025 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:

Investor Relations:

Kevin Gardner

LifeSci Advisors, LLC

kgardner@lifesciadvisors.com

EX-99.2 — EXHIBIT 99.2

EX-99.2

Filename: tm2612012d1_ex99-2.htm · Sequence: 3

Exhibit 99.2

*Address correspondence to:

manuel.hidalgo@nyulangone.org

CT162: Analysis of tumor and biomarker responses in the VIRAGE trial, a randomized phase IIb, open-label, study of

nab-paclitaxel and gemcitabine with/without intravenous VCN-01 in patients with metastatic pancreatic cancer (mPDAC)

Rocio Garcia-Carbonero1

, Roberto Pazo Cid2

, Teresa Macarulla

, Berta Laquente

, Alana Nguyen

, Carmen Guillén

, Andrés Muñoz

, Edward J Kim8

, Mireya Cazorla

, Tara Seery

, Miriam Lobo de Mena

, Chris Nevala-Plagemann12, Vivek Sharma13, Eva Martínez de Castro

, Charles Le

, Ana Mato-Berciano

, Luis A. Rojas

, Carmen Blasco

, Manel Cascallo

, Manuel Hidalgo18,*

1Hospital Universitario 12 de Octubre, Imas 12, Madrid, Spain; 2Hospital Universitario Miguel Servet, Zaragoza, Spain;

3Hospital Universitari Vall d’Hebron, Barcelona, Spain;

4Catalan Institut of Oncology, Barcelona, Spain;

5Weill Cornell Medicine/NYP Hospital, New York, NY;

6Hospital Universitario Ramon y Cajal, Madrid, Spain; 7Hospital Universitario Gregorio Marañón, Madrid, Spain;

8UC Davis Comprehensive Cancer Center, Sacramento;

9Hospital Regional Universitario, Málaga, Spain;

10Hoag Memorial Hospital Presbyterian, Newport Beach, CA;

11Consorcio Hospital General Universitario de Valencia, Valencia, Spain;

12Huntsman Cancer Institute at University of Utah, Salt Lake City;

13University of Louisville, Louisville, KY;

14Hospital Universitario Marqués de Valdecilla, Santander, Spain;

15Theriva Biologics Inc.,

Rockville, MD, USA;

16Theriva Biologics SL., Parets del Vallès, Spain;

18NYU Langone Health Perlmutter Cancer Ctr., NY.

VCN-01 is a clinical-stage oncolytic adenovirus engineered to replicate selectively in cancer cells with an aberrant RB1-E2F pathway. The VCN-01 E1A promoter is modified by inclusion of eight E2F1 binding sites and a 24-bp deletion that promotes viral transcription in cells with elevated free E2F1 and renders the virus replication-deficient in RB1-functional, normal cells. Here, human pancreatic cancer cell lines were exposed to topoisomerase I (topo1) inhibiting chemotherapeutics, irinotecan (IRI), its active metabolite, SN-38, and

topotecan (topo; see Figure A). Notably, in NP-18 cells, E2F1 mRNA was increased ~3-fold compared to untreated cells, and E1A mRNA was boosted ~5-fold in cells treated with VCN-01 + topo1 inhibitors compared to VCN-01 alone. These data suggest that topo1 inhibitor-mediated elevations in E2F1 increase VCN-01 transcription. Based on these promising in vitro results, the potential synergy of VCN-01 plus the liposomal formulation of IRI (

B A C K G R O U N D

Zabilugene almadenorepvec (VCN-01)

is an oncolytic

adenovirus engineered to replicate in cancer cells with

a dysfunctional RB1 pathway. VCN-01 expresses

PH20 hyaluronidase to improve intratumoral viral

dissemination, enhance chemotherapy penetration,

and facilitate immune cell infiltration.

Previous phase I showed that intravenous

administration of VCN-01 is feasible and has an

acceptable safety profile2

. VCN-01 reached and

replicated in tumors, induced an inflammatory tumor

microenvironment, and showed encouraging biological

and clinical activity when administered sequentially

with GnP to patients with mPDAC. In this phase IIb

VIRAGE trial, the primary endpoints of overall survival

(OS) and safety were accomplished (previously

presented at ESMO 2025)

Figure 1. Mechanisms of action of VCN-01

Chemonaïve mPDAC patients were randomized 1:1 to

receive GnP on days 1, 8 and 15 of repeated 28-day

cycles (GnP group) or 2 separate IV doses of VCN-01

(1x1013 vp/dose) 1 week prior to cycles 1 and 4 of GnP

(VCN-01 + GnP group).

• Primary endpoints:

• Overall survival (OS)

• Safety and tolerability

• Secondary objectives:

• Progression free survival (PFS)

• Objective response rates (ORR)

• Disease control rate (DCR)

• Duration of response (DoR)

• Changes of CA 19-9 over time

• Exploratory analyses:

• Viral genomes (vg) in blood

• Neutralizing antibodies (NAbs) in serum

Figure 2. Treatment schedules for the VIRAGE trial

D E S I G N & O B J E C T I V E S

• Patients receiving VCN-01 + GnP had improved OS and PFS compared to GnP alone. The late separation of survival curves

may reflect an immune-mediated mechanism of action.

• Treatment with VCN-01 + GnP resulted in later-emerging, higher magnitude, and more durable responses than GnP alone.

• The OS benefit of VCN-01 + GnP was generally maintained across subgroups including liver metastases, despite a post-recruitment imbalance.

• Patients receiving a second administration of VCN-01 revealed a greater benefit in OS and PFS.

C O N C L U S I O N S

R E S U LT S

Demographics and survival outcomes

Figure 3. Survival outcomes. Kaplan-Meier analysis of OS (a) and PFS (b) in

the patients receiving VCN-01 + ≥1 full

dose of GnP (VCN-01 + GnP) or ≥1 full

dose of GnP (GnP). P values by two-sided log-rank test.

Quality of response

Table 2. OS rates at selected timepoints

Analysis of subgroups

1. Rodríguez-García A et al. Safety and efficacy of VCN-01, an oncolytic adenovirus

combining fiber HSG-binding domain replacement with RGD and hyaluronidase

expression. Clin Cancer Res. 21:1406-18 (2015).

2. Garcia-Carbonero, R. et al. Phase I, multicenter, open-label study of intravenous

VCN-01 oncolytic adenovirus with or without nab-paclitaxel plus gemcitabine in patients

with advanced solid tumors. J. Immunother. Cancer 10, (2022).

3. García-Carbonero, R. et al. 2216MO VIRAGE trial: Randomized phase IIb, open-label, study of nab-paclitaxel and gemcitabine with/without intravenous VCN-01 in

patients with metastatic pancreatic cancer (mPDAC). Ann Oncol. 36:S1146-7 (2025)

The authors are grateful to the patients and their

families, investigators, co-investigators, and

study teams at clinical sites for their participation

and dedication. The clinical study was supported

by Theriva Biologics S.L.

A C K N O W L E D G E M E N T S R E F E R E N C E S

Efficacy in patients receiving four cycles of GnP (two doses of VCN-01)

Patients with liver metastases

Table 3. Secondary efficacy parameters

in patients receiving 4 cycles of GnP

Figure 6. Efficacy in patients receiving

two doses of VCN-01 a, b, Kaplan-Meier analysis of OS (a) and PFS (b) in

the subgroup population of patients

receiving a 4th cycle of GnP (GnP) or a

4th cycle of GnP plus a 2nd dose of

VCN-01 (VCN-01 + GnP). P values by

two-sided log-rank test.

Viral genomes and neutralizing antibodies

Figure 7. Viral genomes in blood (a) and neutralizing antibodies in serum (b). Geometric

mean + 95% CI. The dotted line indicates the limit of quantification. VCN-01 administrations

are indicated by blue arrows.

Figure 5. Analysis of subgroup populations. a, Forest plot of OS in selected subgroups (post-hoc analyses). * For the GnP group, the equivalent of 2 doses of VCN-01 corresponds to patients

who received a 4th cycle of GnP. Hazard ratio P values by Cox Proportional-Hazards model. b, c,

Kaplan-Meier analysis of OS (b) and PFS (c) in the subgroup of patients with liver metastases. P

values by two-sided log-rank test. Multivariate analysis adjusting for liver metastases confirmed

that the survival benefit of the VCN-01 + GnP group was independent of the imbalance in liver

metastases between treatment groups (HR = 0.6 (95% CI, 0.36-1.01), P = 0.055).

a b

Table 3. Secondary efficacy

parameters in overall population

Figure 4. Quality of response. a, Duration of response (DoR). b, Maximum

percentage change in target lesion size from baseline. c, Swimmer’s plot showing

OS in the GnP group (left) and the VCN-01 + GnP group (right); disease

progression, responses, complete responses (CR), VCN-01 doses, and death

events are indicated. d, Time to response, defined as the interval from treatment

initiation to the first documented clinical response. e, Percentage change from

baseline of CA19-9 levels in individual patients at initiation of cycles 3, 6, and 9 of

GnP. The red line indicates the median. P values by two-sided log-rank test (a) and

two-tailed Mann-Whitney test (d).

Table 1. Baseline demographics and clinical characteristics

Characteristic

GnP

(n = 48)

VCN-01 + GnP

(n = 48)

Age (years) Median (range) 68.5 (52-85) 66.0 (41-86)

<70 years, n (%) 26 (54.2) 33 (68.8)

≥70 years, n (%) 22 (45.8) 15 (31.2)

Gender Male, n (%) 22 (45.8) 23 (47.9)

Female, n (%) 26 (54.2) 25 (52.1)

Region European Union, n (%) 41 (85.4) 39 (81.3)

North America, n (%) 7 (14.6) 9 (18.8)

Body Mass Index

(kg/m2

) Median (range) 25.65 (19.1-37.0) 23.70 (17.9-38.4)

ECOG at

randomization

0, n (%) 17 (35.4) 19 (39.6)

1, n (%) 31 (64.6) 29 (60.4)

Liver metastases at

baseline

Yes, n (%) 40 (83.3) 31 (64.6)

No, n (%) 8 (16.7) 17 (35.4)

Number of metastatic

sites

1 or 2, n (%) 38 (79.2) 37 (77.1)

≥3, n (%) 10 (20.8) 11 (22.9)

Primary tumor location Head, n (%) 20 (41.7) 18 (37.5)

Body and tail, n (%) 28 (58.3) 30 (62.5)

CA 19-9 at baseline ≤ 37 UI/ml, n (%) 8 (16.7) 9 (18.8)

> 37 UI/ml, n (%) 40 (83.3) 39 (81.2)

Months GnP (%) VCN-01 + GnP (%)

12 31.9 42.6

15 12.77 35.5

18 8.52 31.1

Parameter GnP

(n = 48)

VCN-01 + GnP

(n = 48)

P value

CR, n (%) 0 (0) 1 (2.1) -

PR, n (%) 15 (31.3) 18 (37.5) -

SD, n (%) 19 (39.6) 18 (37.5) -

PD, n (%) 14 (29.2) 11 (22.9) -

ORR, n (%) 15 (31.3) 19 (39.6) 0.41

DCR, n (%) 34 (70.8) 37 (77.1) 0.59

Parameter

GnP

(n = 29)

VCN-01 + GnP

(n = 34)

P value

CR, n (%) 0 (0) 1 (2.9) -

PR, n (%) 14 (48.3) 18 (52.9) -

SD, n (%) 15 (51.7) 15 (44.1) -

PD, n (%) 0 (0) 0 (0) -

ORR, n (%) 14 (48.3) 19 (55.9) 0.62

DCR, n (%) - - -

GRAPHIC

Filename: tm2612012d1_ex99-1img001.jpg · Sequence: 7

Binary file (5778 bytes)

Download tm2612012d1_ex99-1img001.jpg

GRAPHIC

Filename: tm2612012d1_ex99-2img001.jpg · Sequence: 8

Binary file (520006 bytes)

Download tm2612012d1_ex99-2img001.jpg

XML — IDEA: XBRL DOCUMENT

XML

Filename: R1.htm · Sequence: 10

v3.26.1

Cover

Apr. 17, 2026

Cover [Abstract]

Document Type

8-K

Amendment Flag

false

Document Period End Date

Apr. 17, 2026

Entity File Number

001-12584

Entity Registrant Name

THERIVA BIOLOGICS, INC.

Entity Central Index Key

0000894158

Entity Tax Identification Number

13-3808303

Entity Incorporation, State or Country Code

Entity Address, Address Line One

9605 Medical Center Drive

Entity Address, Address Line Two

Suite 270

Entity Address, City or Town

Rockville

Entity Address, State or Province

Entity Address, Postal Zip Code

20850

City Area Code

301

Local Phone Number

417-4364

Written Communications

false

Soliciting Material

false

Pre-commencement Tender Offer

false

Pre-commencement Issuer Tender Offer

false

Title of 12(b) Security

Common stock, par value $0.001 per share

Trading Symbol

TOVX

Security Exchange Name

NYSEAMER

Entity Emerging Growth Company

false

- Definition

Boolean flag that is true when the XBRL content amends previously-filed or accepted submission.

+ References

No definition available.

+ Details

Name:

dei_AmendmentFlag

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Area code of city

+ References

No definition available.

+ Details

Name:

dei_CityAreaCode

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Cover page.

+ References

No definition available.

+ Details

Name:

dei_CoverAbstract

Namespace Prefix:

dei_

Data Type:

xbrli:stringItemType

Balance Type:

Period Type:

duration

- Definition

For the EDGAR submission types of Form 8-K: the date of the report, the date of the earliest event reported; for the EDGAR submission types of Form N-1A: the filing date; for all other submission types: the end of the reporting or transition period. The format of the date is YYYY-MM-DD.

+ References

No definition available.

+ Details

Name:

dei_DocumentPeriodEndDate

Namespace Prefix:

dei_

Data Type:

xbrli:dateItemType

Balance Type:

Period Type:

duration

- Definition

The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'.

+ References

No definition available.

+ Details

Name:

dei_DocumentType

Namespace Prefix:

dei_

Data Type:

dei:submissionTypeItemType

Balance Type:

Period Type:

duration

- Definition

Address Line 1 such as Attn, Building Name, Street Name

+ References

No definition available.

+ Details

Name:

dei_EntityAddressAddressLine1

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Address Line 2 such as Street or Suite number

+ References

No definition available.

+ Details

Name:

dei_EntityAddressAddressLine2

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Name of the City or Town

+ References

No definition available.

+ Details

Name:

dei_EntityAddressCityOrTown

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Code for the postal or zip code

+ References

No definition available.

+ Details

Name:

dei_EntityAddressPostalZipCode

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Name of the state or province.

+ References

No definition available.

+ Details

Name:

dei_EntityAddressStateOrProvince

Namespace Prefix:

dei_

Data Type:

dei:stateOrProvinceItemType

Balance Type:

Period Type:

duration

- Definition

A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

+ Details

Name:

dei_EntityCentralIndexKey

Namespace Prefix:

dei_

Data Type:

dei:centralIndexKeyItemType

Balance Type:

Period Type:

duration

- Definition

Indicate if registrant meets the emerging growth company criteria.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

+ Details

Name:

dei_EntityEmergingGrowthCompany

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen.

+ References

No definition available.

+ Details

Name:

dei_EntityFileNumber

Namespace Prefix:

dei_

Data Type:

dei:fileNumberItemType

Balance Type:

Period Type:

duration

- Definition

Two-character EDGAR code representing the state or country of incorporation.

+ References

No definition available.

+ Details

Name:

dei_EntityIncorporationStateCountryCode

Namespace Prefix:

dei_

Data Type:

dei:edgarStateCountryItemType

Balance Type:

Period Type:

duration

- Definition

The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

+ Details

Name:

dei_EntityRegistrantName

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

+ Details

Name:

dei_EntityTaxIdentificationNumber

Namespace Prefix:

dei_

Data Type:

dei:employerIdItemType

Balance Type:

Period Type:

duration

- Definition

Local phone number for entity.

+ References

No definition available.

+ Details

Name:

dei_LocalPhoneNumber

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 13e

-Subsection 4c

+ Details

Name:

dei_PreCommencementIssuerTenderOffer

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 14d

-Subsection 2b

+ Details

Name:

dei_PreCommencementTenderOffer

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Title of a 12(b) registered security.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b

+ Details

Name:

dei_Security12bTitle

Namespace Prefix:

dei_

Data Type:

dei:securityTitleItemType

Balance Type:

Period Type:

duration

- Definition

Name of the Exchange on which a security is registered.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection d1-1

+ Details

Name:

dei_SecurityExchangeName

Namespace Prefix:

dei_

Data Type:

dei:edgarExchangeCodeItemType

Balance Type:

Period Type:

duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as soliciting material pursuant to Rule 14a-12 under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 14a

-Subsection 12

+ Details

Name:

dei_SolicitingMaterial

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Trading symbol of an instrument as listed on an exchange.

+ References

No definition available.

+ Details

Name:

dei_TradingSymbol

Namespace Prefix:

dei_

Data Type:

dei:tradingSymbolItemType

Balance Type:

Period Type:

duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as written communications pursuant to Rule 425 under the Securities Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Securities Act

-Number 230

-Section 425

+ Details

Name:

dei_WrittenCommunications

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration