IgM-Enriched Immunoglobulin in Sepsis: Meta-analysis Inconclusive

Key Takeaways

• Randomized adult Pentaglobin evidence in sepsis, severe sepsis, or septic shock showed a directionally favorable but statistically inconclusive mortality pattern.
• Restriction to trials reporting exact 28-day mortality left the mortality signal nonsignificant and imprecise.
• Statistically significant mortality estimates appeared only in exploratory expansions that added a historical non-English Pentaglobin report or indirect formulation-class evidence.
• Harms reporting was incomplete across most Pentaglobin trials, leaving safety evidence at very low certainty.

Sepsis and septic shock continue to drive interest in adjunctive therapies for adults who worsen despite increasingly standardized antimicrobial therapy, source control, hemodynamic resuscitation, and organ support. Immunoglobulin M (IgM)-enriched immunoglobulin remains of interest because its formulation differs biologically from immunoglobulin G-only products, with proposed effects on endotoxin binding, complement modulation, and host defense. That distinction has kept Pentaglobin under consideration in selected critically ill adults even as randomized evidence has remained fragmented across older and newer sepsis eras.

To clarify how much direct trial evidence supports that interest, investigators conducted a systematic review and meta-analysis of randomized controlled trials evaluating adjunctive IgM-enriched immunoglobulin in adults with sepsis, severe sepsis, or septic shock. They searched MEDLINE, PubMed, Embase, CENTRAL, and Web of Science from inception through September 2025. The protocol-concordant core synthesis was limited to English-language Pentaglobin trials with extractable short-term mortality and included six trials with 411 participants. Because historical reports did not describe antecedent care or failure criteria consistently enough to classify treatment-refractory sepsis reproducibly, the review broadened from the registered question to adult sepsis, severe sepsis, and septic shock more generally. The primary endpoint hierarchy prioritized exact 28-day mortality when available and otherwise used the nearest reported short-term mortality endpoint.

In the core Pentaglobin mortality analysis, pooled short-term mortality yielded an odds ratio (OR) of 0.65 with 95% confidence interval (CI) 0.39–1.07 and I2 = 9%, which was directionally favorable but statistically inconclusive. Most core trials favored adjunctive treatment directionally, although the largest study was comparatively neutral. When the analysis was restricted to trials reporting exact 28-day mortality, the estimate remained nonsignificant and imprecise at OR 0.84 with 95% CI 0.50–1.43 and I2 = 0%.

An alternative risk ratio (RR) model produced a similar result at RR 0.76 with 95% CI 0.55–1.06 and I2 = 0%. Statistically significant mortality estimates appeared only in explicitly exploratory expansions: a language-inclusive Pentaglobin model at OR 0.57 with 95% CI 0.34–0.95 and I2 = 16%, and a formulation-class model including Concentrated IgM for Application (CIGMA) at OR 0.64 with 95% CI 0.43–0.94 and I2 = 5%. The authors emphasized that these expanded analyses were not confirmatory direct Pentaglobin evidence. Secondary outcomes, including intensive care unit (ICU) mortality, in-hospital mortality, organ dysfunction measures, and resource use, were too variably defined for robust pooled estimation.

Interpretation of the primary analysis was limited by differences in mortality timing across the six core trials, with exact 28-day mortality reported in three studies and the remaining trials using intensive care unit mortality, overall in-study mortality, or sepsis-related mortality within 6 weeks. The authors noted that low statistical heterogeneity did not eliminate important clinical heterogeneity in enrolled populations, treatment era, comparators, intervention timing, dosing, and trial purpose. Several older Pentaglobin trials also had limited reporting of randomization, allocation concealment, or blinding. Harms reporting was incomplete across most trials, so the lack of a recurring reported safety signal was not treated as proof of safety. Certainty was rated low for short-term mortality and very low for safety, and the significant expanded analyses were framed as exploratory and hypothesis-generating rather than confirmatory.

The authors concluded that current randomized adult evidence does not establish efficacy for adjunctive IgM-enriched immunoglobulin and does not support routine use in unselected sepsis or septic shock. They added that the repeated direction of effect preserves scientific interest, but statistical significance appears only after expansion to historical or indirect evidence.

Clinician Questions

How was short-term mortality defined across Pentaglobin trials in adult sepsis and septic shock?

Short-term mortality was defined hierarchically as exact 28-day mortality when available and otherwise the nearest reported short-term endpoint. The included trials mixed 28-day, ICU, overall in-study, and sepsis-related 6-week mortality measures, which the authors considered noninterchangeable and one reason the pooled estimate required cautious interpretation.

Which randomized evidence counted as direct Pentaglobin data, and what was considered exploratory or indirect?

Direct evidence came from the protocol-concordant English-language randomized Pentaglobin trials. Outside that core set, the review used a historical German-language Pentaglobin report only for a language-inclusive sensitivity analysis and the phase II CIGMA trimodulin trial only for an exploratory formulation-class model, with the latter considered indirect because it studied severe community-acquired pneumonia rather than trial-defined sepsis or septic shock.

Why did the review broaden beyond treatment-refractory sepsis in the registered protocol?

The registered question initially targeted treatment-refractory sepsis, but historical randomized reports did not describe antecedent care, treatment adequacy, or failure criteria consistently enough to classify that phenotype reproducibly. The review was therefore reframed to adult sepsis, severe sepsis, and septic shock more broadly so the synthesis could remain transparent and reproducible.