Presepsin-Guided Anakinra Therapy Cuts Pneumonia Mortality by Half in Groundbreaking INSPIRE Trial

What is the INSPIRE Trial and How Was It Designed?

The INSPIRE phase IIa randomized clinical trial has demonstrated that early presepsin-guided immunotherapy with Anakinra significantly reduces progression to organ dysfunction and mortality in patients with community-acquired pneumonia (CAP) and hospital-acquired pneumonia (HAP). This novel precision approach targets patients at high risk of unfavorable outcomes by utilizing presepsin, a soluble CD14 molecule released from cell membranes after stimulation of innate immune cells by pathogen-associated molecular patterns. The findings, which represent a potential paradigm shift in pneumonia management, show that early identification of patients with presepsin levels exceeding 350 pg/ml can guide targeted immunotherapy before full-blown sepsis develops.

The mortality associated with CAP and HAP remains substantial, with rates ranging from 4% to 28% for CAP and reaching 15-30% for HAP. Progression to sepsis and organ dysfunction represents the common pathway through which pneumonia becomes life-threatening. The INSPIRE trial addresses this critical juncture by intervening at the earliest signs of immune dysregulation. The study enrolled 60 adult patients with CAP or HAP who had a qSOFA (quick Sequential Organ Failure Assessment) score of 1 and presepsin levels above 350 pg/ml, randomizing them 1:1 to receive either standard-of-care (SoC) plus Anakinra or SoC plus placebo. Anakinra, an interleukin-1 receptor antagonist, was administered subcutaneously at 100 mg daily for ten consecutive days, with a minimum required treatment duration of four days. The primary endpoint was a composite of either a two-point or greater increase in SOFA score by day 7 or death by day 90.

Do the Results Support Presepsin-Guided Immunotherapy?

The results were striking. Only 20% of patients in the Anakinra group reached the primary endpoint compared to 50% in the placebo group, representing a 30% absolute risk reduction. This finding was confirmed through logistic regression analysis, which showed that Anakinra treatment was significantly protective against progression to organ dysfunction with an adjusted odds ratio of 0.18 (95% CI: 0.05-0.67; p=0.011). Secondary endpoints also favored the Anakinra group, with 66.7% of Anakinra-treated patients experiencing significant decreases in SOFA score compared to 36.7% in the placebo group. The time to hospital discharge was significantly shorter for patients receiving Anakinra, and both 28-day mortality (13.3% vs. 33.3%) and 90-day mortality (20.0% vs. 43.3%) were substantially reduced. Multiple Cox regression analysis confirmed that Anakinra treatment provided significant survival benefit at both 28 days (adjusted HR 0.29; p=0.049) and 90 days (adjusted HR 0.32; p=0.029).

The study also provided important insights into the mechanism of action of Anakinra in this context. Analysis of peripheral blood mononuclear cells (PBMCs) revealed that patients treated with Anakinra experienced significant decreases in the production capacity of pro-inflammatory cytokines, particularly tumor necrosis factor-alpha (TNFα) and interferon-gamma (IFNγ). The production of IL-1ra by PBMCs also decreased, indicating a reduction in IL-1β production. These findings suggest that Anakinra's clinical benefits stem from its ability to modulate the cytokine response in patients with pneumonia at risk of progression to sepsis. Additionally, the study found that presepsin levels decreased more rapidly in Anakinra-treated patients, with 73.3% of patients in the Anakinra group achieving favorable presepsin kinetics (defined as at least 50% decrease from baseline) compared to 46.7% in the placebo group.

To validate the predictive value of presepsin, the researchers compared outcomes between patients who failed screening due to presepsin levels ≤350 pg/ml and those randomized to the SoC plus placebo group. The analysis confirmed that presepsin levels above 350 pg/ml were significantly associated with progression to organ dysfunction and mortality. Furthermore, post-hoc analyses identified two potential alternatives to presepsin for guiding treatment decisions: the SCORE2 system (suggested by the US FDA for selecting COVID-19 patients who might benefit from Anakinra) and serum calprotectin, a danger-associated molecular pattern protein acting as a TLR4 agonist. Both showed promise as predictors of unfavorable outcomes and response to Anakinra treatment.

Is the Treatment Both Safe and Practically Transformative?

Safety analyses revealed no significant differences in the incidence of serious treatment-emergent adverse events between the Anakinra and placebo groups (33.3% vs. 50.0%), with infections and infestations being the most common serious adverse events in both arms. Non-serious adverse events were also similar between groups, with anemia and diarrhea being the most frequently reported. These findings align with the known safety profile of Anakinra in respiratory tract infections, reinforcing its potential utility in this clinical setting. The results are particularly notable given the high mortality rate (43.3% at 90 days) observed in the placebo group, which underscores the importance of early intervention in high-risk patients identified through biomarker screening.

The INSPIRE trial represents the first randomized controlled evidence supporting early immunotherapy in CAP and HAP guided by biomarkers. The study's two-step strategy – using presepsin to select patients with early activation of the IL-1 cascade and then treating them with Anakinra – offers a precision approach to preventing progression to organ dysfunction and reducing mortality in pneumonia. This strategy could significantly impact clinical practice by providing a means to identify and treat high-risk patients before they develop full-blown sepsis. However, the researchers acknowledge several limitations, including the relatively small sample size, the predominance of CAP rather than HAP patients, and the requirement for healthcare settings capable of providing ICU-level care. Additionally, presepsin testing may not be readily available in many acute care facilities, though the identification of alternative markers like SCORE2 and calprotectin may help overcome this limitation.

What Future Directions Emerge from These Findings?

The findings from INSPIRE raise important questions for future research and clinical practice. How can this precision approach be implemented in diverse healthcare settings, particularly those without access to specialized biomarker testing? Could the combination of presepsin-guided therapy with other treatment modalities further improve outcomes in pneumonia? What is the cost-effectiveness of this approach compared to standard care? And how might these findings influence future guidelines for the management of pneumonia and prevention of sepsis? As the medical community continues to grapple with the significant burden of pneumonia and sepsis, the INSPIRE trial provides valuable insights into a potential path forward for more targeted and effective interventions. Could this biomarker-guided immunotherapy approach be extended to other types of infections beyond respiratory tract infections, and what might be the implications for sepsis management more broadly?

The implications of this study extend beyond pneumonia management. By demonstrating the efficacy of early, biomarker-guided immunotherapy in preventing progression to sepsis, the INSPIRE trial contributes to the broader understanding of sepsis pathophysiology and the potential for targeted interventions at critical points in disease progression. As healthcare continues to move toward precision medicine approaches, the presepsin-guided Anakinra treatment strategy exemplified in this trial may serve as a model for similar interventions in other conditions characterized by dysregulated inflammatory responses. The challenge now lies in translating these promising findings into practical, widely applicable clinical protocols that can benefit patients across diverse healthcare settings.

How Were the Trial’s Operational and Analytical Aspects Addressed?

The study was conducted between March 2023 and June 2024 across four Internal Medicine departments of public hospitals in Greece. These sites were specifically selected for their ability to provide intensive care unit (ICU) level care, including non-interventional and mechanical ventilation as well as administration of vasopressors when needed. This selection was important given the severity of the conditions being treated and the possibility of disease progression requiring advanced care. The trial design included daily follow-up visits from day 1 to day 10 and additional visits on days 14, 28, and 90, ensuring comprehensive patient monitoring throughout the study period.

Of the 371 patients assessed for eligibility, only 60 met all inclusion criteria and were randomized. The patient population predominantly had community-acquired pneumonia (93.3% in both treatment arms), with just a small fraction (6.7%) presenting with hospital-acquired pneumonia. Patients were well-matched at baseline with similar demographics, severity scores (APACHE II, SOFA, CURB65, PSI), comorbidities, and laboratory values. The mean age was 70.9 years in the placebo group and 74.0 years in the Anakinra group, with a higher proportion of males in both arms. Common comorbidities included type 2 diabetes mellitus, chronic heart failure, chronic obstructive pulmonary disease, and chronic renal disease.

Microbiology findings showed a variety of pathogens isolated from patients, with Staphylococcus aureus being the most common (20.0% in placebo group and 23.3% in the Anakinra group), followed by Klebsiella pneumoniae (16.7% in placebo group only) and Pseudomonas aeruginosa. Viral pathogens were identified in 6.7% of placebo patients and 13.3% of Anakinra patients. Standard-of-care antibiotic treatments were similar between groups, with piperacillin/tazobactam being the most frequently used (56.7% in placebo vs. 46.7% in Anakinra group), followed by macrolides and third-generation cephalosporins. Notably, a substantial proportion of patients in both groups received intravenous corticosteroids as part of standard care (53.3% in placebo and 50.0% in the Anakinra group).

The investigators employed a unique biomarker-guided approach to identify patients at risk of unfavorable outcomes. Presepsin levels were measured using the PATHFAST assay, which is widely available as a point-of-care bedside test with a turnaround time of just 15 minutes. This rapid testing capability facilitated prompt patient stratification and treatment initiation. Patients with presepsin levels above 350 pg/ml were enrolled, while those with levels below this threshold were followed for comparison purposes. The median presepsin level at baseline was 570.5 pg/ml in the placebo group and 565.0 pg/ml in the Anakinra group.

Regarding disease progression, the study revealed that 37 patients (61.7% of the total study population) progressed to require ICU-level care – 20 patients (66.7%) from the placebo group and 17 patients (56.7%) from the Anakinra group. Of these, 33 patients required high-flow oxygenation, with 11 (33.3%) dying by day 28. Six patients progressed further to mechanical ventilation, with four (66.7%) dying by day 28. Nineteen patients needed vasopressors, with 11 (57.9%) dying by day 28. The overall 28-day mortality rate for patients requiring ICU-level care was 32.4%, increasing to 40.5% by day 90. The causes of death included respiratory failure, new sepsis, pulmonary embolism, status epilepticus, sudden cardiac arrest, candidemia, and COVID-19 pneumonia.

The post-hoc analysis of serum calprotectin (S100A8/A9) provided additional insights into potential biomarkers for treatment guidance. A calprotectin cut-off of 6.8 ng/ml was found to predict unfavorable outcomes with an odds ratio of 4.09 (95% CI: 1.37-12.25; p=0.012). Patients with calprotectin levels ≥6.8 ng/ml had worse outcomes, and the time to >50% decrease in calprotectin was significantly shorter among patients receiving Anakinra, suggesting its utility as a marker for treatment response monitoring. The method for calprotectin measurement – particle-enhanced turbidimetric immunoassay with a 20-minute turnaround time – is CE-IVD marked, making it potentially suitable for clinical implementation.

The study also highlighted the ongoing debate about corticosteroid use in severe CAP. The multiple Cox regression model suggested that intake of corticosteroids was associated with unfavorable 90-day outcomes, contrary to some previous research findings. This discrepancy with other studies, such as a randomized trial of 795 patients in France that showed reduced 28-day mortality with intravenous hydrocortisone, versus the REMAP-CAP platform trial that found no benefit, underscores the need for additional research in this area.

The INSPIRE trial was powered under the assumption that the primary endpoint would be met by 65% of patients in the placebo group and 30% in the Anakinra group, based on data from previous SAVE and SAVE-MORE trials. With 30 patients in each arm, the study achieved 80% power at a 5% significance level. The actual results showed even greater benefit than anticipated, with only 20% of Anakinra-treated patients meeting the primary endpoint compared to 50% in the placebo group.

In conclusion, the INSPIRE trial provides compelling evidence for a precision medicine approach to pneumonia management using biomarker-guided immunotherapy. By identifying patients at risk of progression to organ dysfunction through presepsin levels and intervening early with Anakinra, clinicians may be able to significantly reduce mortality and improve outcomes. While challenges remain in implementation and further validation is needed, this study represents an important step toward more targeted and effective treatments for pneumonia and prevention of sepsis.

Summary

The INSPIRE phase IIa randomized clinical trial demonstrates that early presepsin-guided immunotherapy with Anakinra significantly reduces progression to organ dysfunction and mortality in patients with community-acquired pneumonia (CAP) and hospital-acquired pneumonia (HAP). The study enrolled 60 adult patients with CAP or HAP who had a qSOFA score of 1 and presepsin levels above 350 pg/ml, randomizing them to receive either standard care plus Anakinra or standard care plus placebo. Only 20% of patients in the Anakinra group reached the primary endpoint of progression to organ dysfunction or death compared to 50% in the placebo group, representing a 30% absolute risk reduction. The 28-day mortality was 13.3% versus 33.3%, and 90-day mortality was 20.0% versus 43.3% in favor of Anakinra treatment. Anakinra, an interleukin-1 receptor antagonist administered subcutaneously at 100 mg daily for ten days, modulated cytokine responses by decreasing production of pro-inflammatory cytokines including tumor necrosis factor-alpha and interferon-gamma. The safety profile was favorable, with no significant differences in serious adverse events between groups. The study conducted across four Greek hospitals between March 2023 and June 2024 utilized presepsin as a biomarker measured by the PATHFAST point-of-care assay with a 15-minute turnaround time. Post-hoc analyses identified alternative biomarkers including the SCORE2 system and serum calprotectin, which showed promise as predictors of unfavorable outcomes. This two-step precision approach—using presepsin to select patients with early activation of the IL-1 cascade and treating them with Anakinra—offers a novel strategy for preventing progression to sepsis and reducing mortality in pneumonia patients before full-blown sepsis develops.