Armata Pharmaceuticals Unveils Promising Results for Phage Therapy

Armata Pharmaceuticals, Inc. announced encouraging findings from its Phase 2a diSArm study of AP-SA02, a bacteriophage cocktail targeting Staphylococcus aureus, during a presentation at IDWeek 2025. This study examined the potential of AP-SA02 as a treatment for complicated Staphylococcus aureus bacteremia (SAB) and showcased results that support further clinical development.

The presentation, delivered by Dr. Loren G. Miller, a prominent professor at the David Geffen School of Medicine at UCLA and Chief of the Division of Infectious Diseases at Harbor-UCLA Medical Center, highlighted the trial’s positive outcomes. “The results of the diSArm study confirm, for the first time in a randomized clinical trial, the efficacy of intravenous phage therapy for S. aureus bacteremia,” Dr. Miller stated. He emphasized the significance of these findings, which could lead to a Phase 3 superiority study aimed at establishing AP-SA02 as a standard treatment for this severe infection.

Dr. Deborah Birx, Chief Executive Officer of Armata, expressed her gratitude to Dr. Miller and the research team. She stated, “The positive results from the diSArm study represent another significant achievement for Armata as we aim to advance AP-SA02 into a pivotal trial.” Birx also acknowledged the contributions of the independent adjudication committee, led by Dr. Vance Fowler, which confirmed the study’s safety and efficacy.

The Phase 2a study involved 42 patients, with 29 receiving AP-SA02 alongside the best available antibiotic therapy (BAT) and 13 receiving a placebo. The study found that approximately 38% of patients in both groups had methicillin-resistant S. aureus (MRSA) as the causative pathogen.

Clinical outcomes were assessed at key time points: 12 days post-treatment and four weeks after completing BAT. The AP-SA02 group demonstrated a clinical response rate of 88% compared to 58% in the placebo group, a statistically significant difference (p = 0.047). No patients in the AP-SA02 group experienced non-response or relapse at either follow-up point, in stark contrast to the placebo group, which showed a 25% rate of non-response or relapse.

Patients treated with AP-SA02 also exhibited trends towards faster recovery, including quicker normalization of C-reactive protein levels and shorter hospital stays. The treatment was well-tolerated, with only 6% of participants in the AP-SA02 group reporting treatment-emergent adverse events, compared to none in the placebo group.

The findings from this study suggest that the defined genomic variants present in AP-SA02 may enable a rapid, strain-specific response to each patient’s S. aureus isolate. This adaptability could play a crucial role in the efficacy of phage therapy, allowing for more personalized treatment approaches.

The results strongly support the advancement of AP-SA02 into a Phase 3 trial, which Armata plans to initiate in 2026, pending regulatory approval from the U.S. Food and Drug Administration (FDA). The company is currently engaged with the FDA to discuss the trial design.

Armata’s commitment to developing high-purity, pathogen-specific bacteriophage therapeutics positions it at the forefront of addressing antibiotic-resistant infections, which are a growing public health concern. The diSArm study represents a significant milestone in this pursuit, moving closer to offering a novel treatment option for patients grappling with complicated S. aureus bacteremia.

IDWeek 2025, where the findings were presented, is a collaborative annual meeting focused on advancing science and improving care in infectious diseases. The event took place from October 19 to 22 in Atlanta, Georgia, showcasing the latest research and innovations in the field.

As Armata Pharmaceuticals continues its efforts, the implications of this research underline the potential for bacteriophage therapy as a vital tool in combating severe bacterial infections that resist conventional treatments.