scientist in lab

Staphylococcus aureus Phage Product Candidate


AP-SA02 is a novel biologic product candidate comprising natural lytic phages that target the problematic pathogen, Staphylococcus aureus, and offers robust therapeutic attributes, including:

  • Potent antimicrobial activity against approximately 95% of S. aureus clinical isolates tested, including drug-resistant isolates (MRSA: methicillin-resistant S. aureus and VRSA: vancomycin-resistant S. aureus);
  • Unique mechanism of action offers independent or synergistic benefit with standard of care antibiotics;
  • Component phages are stable and retain infectivity after exposure to relevant biological fluids;
  • Penetrates pre-existing S. aureus biofilms.

Clinical trial material of AP-SA02 is currently manufactured under cGMP at our production facility in California to support the required regulatory filing(s) for clinical studies in the U.S. and ex-U.S. 

Armata is committed to developing novel phage therapies that specifically address areas of high need which includes drug-resistant and difficult-to-treat infections such as S. aureus bacteremia.

The “diSArm” study is a Phase 1b/2a, randomized, double‐blind, placebo‐controlled, multiple ascending dose escalation study of the safety, tolerability, and efficacy of intravenous AP‐SA02 as an adjunct to best available antibiotic therapy compared to best available antibiotic therapy alone for the treatment of adults with bacteremia due to Staphylococcus aureus. The objectives of this study are to: (i) demonstrate safety and tolerability of multiple different dose levels of AP-SA02; (ii) evaluate optimal dosing through safety, pharmacokinetics and microbial efficacy; and (iii) explore efficacy through evaluation of key meaningful endpoints. The study is being conducted at sites in the United States and also at sites abroad in Australia. The Phase 2a diSArm study is expected to fully enroll by the end of 2024.

The Phase 1b/2a study is partially funded by a $16.3 million award through the Medical Technology Enterprise Consortium (MTEC) managed by the Naval Medical Research Center. The MTEC award is funded by the Defense Health Agency and Joint Warfighter Medical Research Program.

We anticipate findings from the Phase 1b/2a study will provide the basis for constructing a robust trial strategy for registration which can be the basis for an End-of-Phase-2 meeting with the FDA that enables us to obtain agreement on a path to approval in 2025.

Target Market and Medical Need

Bacteremia is a bacterial infection of the bloodstream. A common diagnosis, the Centers for Disease Control and Prevention (CDC) estimates that up to 1.7 million people in the U.S. develop bacteremia each year. S. aureus is the most commonly identified pathogen in both hospital- and community-acquired blood stream infections. Annually in the U.S. there are approximately 200,000 hospitalizations for S. aureus bacteremia (SAB). Despite conventional antibiotics, mortality in SAB results in death of up to 40% of all cases and 57% of patients over the age of 85. Patients with comorbidities such as alcoholism, malignancy, diabetes, end-stage renal disease requiring hemodialysis, and immunosuppression are at even higher risk for death when SAB develops. Age-adjusted mortality assessments show that SAB mortality is higher than that of AIDS, tuberculosis, or viral hepatitis, and comparable to mortality rates for breast or prostate cancer. Outcomes are even poorer for SAB due to methicillin-resistant S. aureus (MRSA), classified as a serious threat to global health by the CDC and a high priority threat by the World Health Organization, with higher rates of complications and increased mortality as compared to methicillin-susceptible S. aureus (MSSA). Average hospital costs to patients with nosocomial SAB ranges between $40,000 (MSSA) and $114,000 (MRSA). Treatment failures are common in SAB, with highest rates due to MRSA. These failures can be attributed in part to poor penetration of some tissues by antibiotics, slow onset of bactericidal effects, emerging resistance patterns, and biofilm formation. While biofilms can render traditional antibiotics ineffective, phages may have the ability to penetrate the biofilm allowing rapid and efficient infection of the host and amplification at the site of infection. Until the recent FDA approval of Zevtera (intravenously administered cephalosporin antibiotic), daptomycin (approved in 2005; based on clinical cure rates of <50%) and vancomycin were the only two antibiotics with label indications in the U.S. for the treatment of SAB, and the emergence of drug-resistant S. aureus isolates, including to these two standard of care drugs, represents a major threat in terms of increasing morbidity, mortality and health care utilization.

Additional Clinical Indications for AP-SA02

Improved patient outcomes are needed for other Staphylococcal infections, in settings such as prosthetic joint infections and wound infections, for which antimicrobial resistance is a growing concern. We believe AP-SA02 could also have a meaningful impact in these indications, particularly infections caused by methicillin-resistant S. aureus (MRSA). In August, 2022, the U.S. FDA cleared Armata’s Investigational New Drug (IND) application for AP-SA02 in a second indication, prosthetic joint infection (PJI).