Design, conduct, and analysis of a multicenter, pharmacogenomic, biomarker study in matched patients with severe sepsis treated with or without drotrecogin Alfa (activated)

Pharmacogenomic biomarkers do not predict response to drotrecogin alfa in patients with severe sepsis

Purpose

To explore potential design for pharmacogenomics trials in sepsis, we investigate the interaction between pharmacogenomic biomarkers and response to drotrecogin alfa (activated) (DrotAA). This trial was designed to validate whether previously identified improved response polymorphisms (IRPs A and B) were associated with an improved response to DrotAA in severe sepsis.

Methods

Patients with severe sepsis at high risk of death, who received DrotAA or not, with DNA available were included and matched to controls adjusting for age, APACHE II or SAPS II, organ dysfunction, ventilation, medical/surgical status, infection site, and propensity score (probability that a patient would have received DrotAA given their baseline characteristics). Independent genotyping and two-phase data transfer mitigated bias. The primary analysis compared the effect of DrotAA in IRP+ and IRP− groups on in-hospital 28-day mortality. Secondary endpoints included time to death in hospital; intensive care unit (ICU)-, hospital-, and ventilator-free days; and overall DrotAA treatment effect on mortality.

Results

Six hundred and ninety-two patients treated with DrotAA were successfully matched to 1935 patients not treated with DrotAA. Genotyping was successful for 639 (DrotAA) and 1684 (nonDrotAA) matched patients. The primary hypothesis of a genotype-by-treatment interaction (assessed by conditional logistic regression analysis) was not significant (P = 0.30 IRP A; P = 0.78 IRP B), and there was no significant genotype by treatment interaction for any secondary endpoint.

Conclusions

Neither IRP A nor IRP B predicted differential response to DrotAA on in-hospital 28-day mortality.

ClinicalTrials.gov registration NCT01486524

Electronic supplementary material

The online version of this article (10.1186/s13613-018-0353-2) contains supplementary material, which is available to authorized users.

Biomarkers in sepsis

There is much enthusiasm and interest in sepsis biomarkers, particularly because sepsis is a highly lethal condition, its diagnosis is challenging, and even simple treatment with antibiotics has led to serious adverse consequences such as emergence of resistant pathogens. Yet development of a sepsis biomarker requires many more steps than simply finding an association between a particular molecule and a clinical state or outcome. Demonstration of improvement of therapeutic practice using receiver-operating characteristic and other analyses is important. Validation in independent, prospective and, preferably, multicenter trials is essential. Many promising candidate sepsis biomarkers have recently been proposed. While procalcitonin (PCT) is currently the most studied sepsis biomarker, evidence of potential value has been found for a wide array of blood biomarkers including proteins, mRNA expression in whole blood or leukocytes, micro-RNAs (miRNA), pathogen and host DNA, pathogen and host genetic variants and metabolomic panels, and even in the novel use of currently available clinical data. While the most common early reports link putative sepsis biomarker levels to severity of illness and outcome (prognostic), this is not anticipated to be their primary use. More important is the distinction between infection and noninfectious inflammatory responses (diagnostic) and the use of sepsis biomarkers to direct therapy (predictive).