Precision Immunotherapy Shows Promise for Improving Organ Dysfunction in Sepsis

Sepsis remains one of the most complex and deadly conditions encountered in critical care. Characterized by life-threatening organ dysfunction caused by a dysregulated host response to infection, the syndrome affects millions of patients worldwide each year and continues to challenge clinicians seeking effective treatments. A growing body of research suggests that the heterogeneity of immune responses in sepsis may explain why many previous immunotherapy trials have failed.

A new multicenter randomized clinical trial, known as the ImmunoSep study, Precision Immunotherapy to Improve Sepsis Outcomes, The ImmunoSep Randomized Clinical Trial, published in JAMA, Caring for the Critically Ill Patient, examined whether a precision immunotherapy strategy tailored to specific immune dysfunction patterns could improve outcomes among patients with sepsis. The results suggest that targeting treatment based on the immune profile may improve organ dysfunction during the early phase of illness.

“Among patients with sepsis, a precision immunotherapy strategy targeting macrophage activation–like syndrome and sepsis-induced immunoparalysis improved organ dysfunction by day 9 compared with placebo,” the authors wrote.

Understanding Immune Dysregulation in Sepsis

Sepsis does not present as a single uniform disease. Instead, patients may experience widely different immune responses, ranging from hyperinflammation to profound immunosuppression. Researchers have increasingly proposed that therapies should be guided by biomarkers that identify each patient's underlying immune state.

In the ImmunoSep trial, investigators focused on 2 specific patterns of immune dysregulation. The first was macrophage activation–like syndrome, a hyperinflammatory condition driven by excessive interleukin 1 production. The second was sepsis-induced immunoparalysis, a hypoinflammatory state characterized by immune cell exhaustion and apoptosis.

To classify patients, researchers measured blood ferritin levels and the number of human leukocyte antigen DR receptors on CD45/CD14 monocytes. Patients with ferritin levels greater than 4420 ng/mL were categorized as having macrophage activation–like syndrome. Patients with ferritin levels of 4420 ng/mL or less and fewer than 5000 HLA-DR receptors on CD45/CD14 monocytes were classified as having sepsis-induced immunoparalysis.

Study Design and Patient Population

The randomized, double-anonymized, placebo-controlled trial was conducted across 33 study sites in 6 countries. Eligible participants were adults with sepsis associated with community-acquired pneumonia, hospital-acquired pneumonia, ventilator-associated pneumonia, or primary bacteremia.

“The primary analysis included all patients randomized, who did not withdraw their consent or requested removal of all data,” the authors wrote. “For patients who died before day 9, all values from the death day until day 15 were replaced by 24 (the maximum SOFA score). For patients discharged home or lost to follow-up before day 9, the last recorded SOFA score was carried forward. The SOFA score was parameterized as a continuous variable for all analyses.”

Among 672 patients screened for eligibility, 281 were randomized. Five patients later withdrew consent, leaving 276 participants in the primary analysis population. The mean age was 70 years with a standard deviation of 13 years, and 93 participants, representing 33.7%, were female.

Participants were randomized to receive either standard care plus precision immunotherapy or standard care plus placebo. Treatment was administered for up to 15 days.

Patients identified with macrophage activation–like syndrome received intravenous anakinra, a recombinant human interleukin 1 receptor antagonist. Those with sepsis-induced immunoparalysis received subcutaneous recombinant human interferon gamma.

Primary Outcome: Improvement In Organ Dysfunction

The primary endpoint of the trial was a decrease of at least 1.4 points in the mean Sequential Organ Failure Assessment (SOFA) score from baseline by day 9. The SOFA score evaluates dysfunction across 6 organ systems and ranges from 0 to 24, with higher scores indicating greater severity of organ failure.

Results showed a significant improvement in the precision immunotherapy group. The primary endpoint was achieved in 46 of 131 patients (35.1%) compared with 26 of 145 patients (17.9%) in the placebo group. The difference between groups was 17.2 % with a 95% confidence interval of 6.8% to 27.2%.

Adjusted analysis also supported the benefit of the precision strategy. After controlling for baseline illness severity, the adjusted odds ratio for achieving SOFA improvement by day 9 was 2.49, with a 95% confidence interval of 1.42 to 4.36.

Secondary Outcomes

Several secondary outcomes also favored the precision immunotherapy strategy.

A decrease of at least 1.4 points in mean SOFA score by day 15 occurred in 52 of 131 patients (39.7%) in the precision immunotherapy group, compared with 34 of 145 patients (23.4%) in the placebo group.

Among patients evaluated for reversal of sepsis-induced immune dysfunction, improvement occurred in 46 of 59 patients (78.0%) in the precision immunotherapy group, compared with 32 of 66 patients (48.5%) in the placebo group.

Investigators also reported improved infection outcomes. By day 15, infection resolution occurred in 58 of 131 patients (44.3%) in the precision immunotherapy group and in 46 of 145 patients (31.7%) in the placebo group.

Mortality Outcomes

Despite improvements in organ dysfunction, mortality outcomes were not statistically different between groups.

Twenty-eight-day mortality occurred in 57 of 131 patients (43.5%) in the precision immunotherapy group and in 72 of 145 patients (49.7%) in the placebo group. Ninety-day mortality was 90 of 131 patients (68.7%) in the precision immunotherapy group and 98 of 145 patients (67.6%) in the placebo group.

Safety Findings

A total of 1069 serious treatment-emergent adverse events were reported in 245 patients, representing 88.8 % of participants. Thirteen events were considered serious adverse reactions that were probably or possibly related to the study drug. “[Two] serious adverse reactions were reported in the anakinra group, 7 in the recombinant human interferon gamma group, and 4 in the placebo group. Six serious adverse reactions were considered suspected unexpected serious adverse reactions for 5 patients; 3 patients (2.5%) received placebo and 2 patients (1.9%) recombinant human interferon gamma.”

Researchers noted an increased incidence of anemia in the anakinra group and hemorrhage in the recombinant human interferon gamma group. Overall, investigators reported no major safety concerns associated with the precision immunotherapy approach.

Implications for Sepsis Treatment

The findings highlight the growing importance of precision medicine in critical care. Previous immunotherapy trials in sepsis often failed to demonstrate benefit, in part because they treated the condition as a single disease rather than a spectrum of immune responses.

By identifying patients with distinct immune dysfunction patterns and tailoring treatment accordingly, the ImmunoSep trial demonstrated measurable improvement in organ dysfunction within the first 9 days of illness.

However, investigators also emphasized the need for further research. The primary endpoint was a surrogate outcome based on organ failure scores rather than patient-centered outcomes such as survival or long-term recovery. In addition, laboratory testing required to classify immune states may not yet be widely available in all hospitals.

Still, the results suggest that biomarker-guided immunotherapy could represent an important step toward more personalized treatment strategies for sepsis.

As researchers continue to explore immune profiling and targeted therapies, precision approaches may help move sepsis treatment beyond one-size-fits-all protocols toward individualized care that addresses the underlying immune response driving each patient’s illness.