Sepsis, a life-threatening organ dysfunction caused by a dysregulated host response to infection, presents a major clinical challenge globally. This condition is notably heterogeneous. Consequently, standard treatment protocols often fail to address the varied immune responses across different patients. The recent ImmunoSep Randomized Clinical Trial, published in JAMA, sought to address this challenge using Precision Immunotherapy Sepsis. This groundbreaking phase 2b study investigated a biomarker-guided approach, targeting specific immune phenotypes to improve patient outcomes. The results signal a significant shift toward personalized care for critically ill patients.
Trial Design & Patient Stratification
The ImmunoSep Trial utilized a robust randomized, double-blind, double-dummy, placebo-controlled design across six countries. Researchers enrolled 276 patients who met the Sepsis-3 definition and had specific infections like pneumonia or bacteremia. Therefore, patients were stratified into two distinct immune endotypes. The first group was Macrophage Activation-Like Syndrome (MALS), characterized by hyperinflammation and identified by high blood ferritin levels (typically >4420 ng/mL). Conversely, the second group had Sepsis-Induced Immunoparalysis (SII), a state of profound anti-inflammation and immune suppression. Biomarker stratification ensures that patients receive the appropriate immune-modulating treatment.
Precision Immunotherapy Sepsis: Targeted Treatments
The core of the study involved tailoring the treatment precisely to the patient’s immune status. Patients diagnosed with MALS received anakinra, a recombinant interleukin-1 receptor antagonist, administered intravenously. Anakinra acts to suppress the exaggerated pro-inflammatory response seen in MALS. Alternatively, patients with SII received recombinant human interferon-gamma (rhIFNγ) subcutaneously. This drug works to stimulate the suppressed immune system and restore its function. Meanwhile, the control group received both intravenous and subcutaneous placebo to maintain the double-blind nature of the trial. The use of a double-dummy design preserved blinding despite the different routes of administration for the active drugs.
Clinical Outcomes and Future Directions for Precision Immunotherapy Sepsis
The primary endpoint of the ImmunoSep trial was a significant improvement in organ function. Specifically, this was defined as a decrease of at least 1.4 points in the mean Sequential Organ Failure Assessment (SOFA) score from baseline to day 9. Importantly, the precision immunotherapy group achieved the primary endpoint in 35.1% of patients, compared to only 17.9% in the placebo group ($P=0.002$). Furthermore, patients with MALS who received anakinra showed particularly strong results. Consequently, the trial’s findings validate the strategy of using biomarkers to guide immunotherapy. However, the study noted that 28-day mortality was not statistically different between the two groups. Therefore, further large-scale Phase 3 trials are warranted to confirm the mortality benefit and broaden the application of Precision Immunotherapy Sepsis for the majority of patients.
Frequently Asked Questions
Q1: What is the primary finding of the ImmunoSep Randomized Clinical Trial?
The trial found that precision immunotherapy tailored to a patient’s immune endotype significantly improved organ dysfunction (SOFA score decrease of ≥1.4 points) by day 9, compared to a placebo group.
Q2: What are the two immune endotypes of sepsis targeted in this trial?
The two immune endotypes targeted were Macrophage Activation-Like Syndrome (MALS), characterized by hyperinflammation, and Sepsis-Induced Immunoparalysis (SII), a state of immune suppression.
Q3: What specific immunotherapies were used for the two sepsis endotypes?
Patients with MALS received anakinra to suppress the immune response, while patients with SII received recombinant human interferon-gamma (rhIFNγ) to stimulate immune function.
References
- Giamarellos-Bourboulis EJ et al. Precision Immunotherapy to Improve Sepsis Outcomes: The ImmunoSep Randomized Clinical Trial. JAMA. 2025 Dec 08. doi: 10.1001/jama.2025.24175. PMID: 41359996.
- Adding Precision Immunotherapy Improved Sepsis Outcomes. MedPage Today. Available at: https://www.medpagetoday.com. Accessed December 9, 2025.
- ImmunoSep (Personalised Immunotherapy in Sepsis) international double-blind, double-dummy, placebo-controlled randomised clinical trial: study protocol. BMJ Open. 2022 Dec 20;12(12):e067251.