Ribaxamase

Interim blinded safety and pharmacokinetic data to be presented at the Congress of the European Society of Clinical Microbiology and Infectious Diseases (ESCMID Global) ROCKVILLE, MD, USA I April 10, 2025 I 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 the presentation of the previously disclosed blinded safety and pharmacokinetic (PK) data from the ongoing Phase 1b/2a randomized, double-blinded, placebo-controlled clinical trial of SYN-004 (ribaxamase) in allogeneic hematopoietic cell transplant (HCT) recipients for the prevention of acute graft-versus-host-disease (aGVHD). These data will be featured in an ePoster Flash Session oral presentation at the Congress of the European Society of
 Clinical Microbiology and Infectious Diseases (ESCMID Global), taking place in Vienna, Austria from April 11-15, 2025. Details on ePoster number E0145 can be found below. About the Phase 1b/2a Clinical Trial The ongoing randomized, double-blinded, placebo-controlled Phase 1b/2a clinical trial is being conducted at Washington University School of Medicine in St. Louis. The trial is designed to evaluate the safety, tolerability, and potential absorption of oral SYN-004 (150 mg q.i.d. for a maximum of 28 days) into the systemic circulation of allogeneic HCT recipients who receive an IV antibiotic to treat fever. To mitigate risk, Cohort 1 of the study administered meropenem as the study-assigned antibiotic. Meropenem is a carbapenem antibiotic that is not metabolized by SYN-004. Patients in Cohort 2 were administered piperacillin/tazobactam as the study-assigned antibiotic and patients in Cohort 3 will receive cefepime. Piperacillin and cefepime can be metabolized by SYN-004. The trial is also designed to evaluate potential protective effects of SYN-004 on the gut microbiome as well as generate preliminary information on potential therapeutic benefits and patient outcomes of SYN-004 in allogeneic HCT recipients. The trial is expected to enroll up to 36 participants with three sequential cohorts, each evaluating a different study-assigned IV beta-lactam antibiotic. Safety and pharmacokinetic data for each cohort is reviewed by an independent Data and Safety Monitoring Committee that makes a recommendation on whether to proceed to the next IV beta-lactam antibiotic. More information on the study is available here ( NCT04692181 ). About SYN-004 (ribaxamase) SYN-004 (ribaxamase) is an oral prophylactic therapy designed to degrade certain IV beta-lactam antibiotics within the GI tract and maintain the natural balance of the gut microbiome for the prevention of Clostridioides difficile infection (CDI), overgrowth of pathogenic organisms, the emergence of antimicrobial resistance (AMR) and acute graft-versus-host-disease (aGVHD) in allogeneic hematopoietic cell transplant (HCT) recipients. Allogeneic HCT recipients routinely receive long courses of IV beta-lactam antibiotics to treat infection following conditioning therapy. Antibiotic-mediated damage of the gut microbiome in allogeneic HCT recipients may lead to adverse outcomes including CDI, VRE colonization and potentially fatal bacteremia and aGVHD. A previously completed placebo-controlled Phase 2b clinical trial of 412 patients demonstrated SYN-004 protected the gut microbiome from antibiotic-mediated dysbiosis. Patients who received SYN-004 also demonstrated significantly better maintenance and recovery of the gut microbiome as well as lower incidences of new colonization by opportunistic and potentially pathogenic microorganisms such as VRE. 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 are: (1) 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; (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 . SOURCE: Theriva Biologics