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Accellix CD64




Accellix CD64 Sepsis Marker

The first LeukoDx product is for the rapid diagnosis and monitoring of sepsis, and itis based on three technological pillars: Accellix flow cytometer capable of accurately reading multiple biomarkers simultaneously, disposable Accellix cartridges developed exclusively for this reader, and the exclusive license to use cell surface marker, CD64, within a POC diagnostic platform.

Sepsis

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Sepsis is a medical condition characterized by a whole-body inflammatory state caused by severe infection. In the early stages, the clinical manifestations of sepsis are non-specific, yet early recognition is key to reducing sepsis-related mortality. In the developed world about 0.2 to 3 people per 1000 get sepsis yearly. This corresponds toabout a million cases per year in the US alone. In fact, every few seconds, someone in the world dies of sepsis i. Globally, an estimated 20–30 million cases of sepsis occur each year. Sepsis kills 28-50% i, far more than the number of U.S. deaths from prostate cancer, breast cancer and AIDS combined. In the developing world, sepsis accounts for 60 to 80% of all deaths. Those who survive often have to deal with life-long effects of organ and tissue damage.  Statistics show that every hour delay in the diagnosis of sepsis yields a significant increase in the chance of patient mortality (up to 8%iii). The incidence of sepsis is increasing dramatically, due to the ageing population and despite the advantages of modern medicine including vaccines, antibiotics and intensive care. Hospitalizations for sepsis have more than doubled over the last 10 yearsiv, v. An estimated $20.3 billion was spent on hospitalizations for sepsis in the US in 2012 vi, aggregate costs for treating patients hospitalized for this condition increased on average annually by 11.9%.

In EU, it has been estimated that a typical episode of sepsis costs healthcare services approx. €25k. The estimated annual economic burden of sepsis in Germany is € 5.0 billionvii.

 

Diagnosis of Sepsis

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The Accellix CD64 Assay, given a drop of patient blood, will accurately identify, within 20 minutes, whether or not a patient is septic, to enable rapid medical decisions and to save lives in the ICU, ERs and neonatal units. The assay can be further used, in addition to diagnostics, to monitor sepsis treatment to ascertain whether treatment is working and whether a patient can be taken off antibiotics. The indirect impact of this will be a decrease in antibiotic use, as fewer non-septic patients will be treated and antibiotic use can be stopped when monitoring indicates this is an option.

Today doctors rely on clinical observation of a collection of non-specific symptoms, which could easily be confused with indications for a number of conditions. Signs of infection and inflammation are similar, making diagnosis of bacterial infections difficult, and traditional markers for infection and sepsis (temperature, leucocytosis, CRP) suffer from lack of sensitivity and specificity.

Several laboratory tests have been evaluated for differentiating between infected and non-infected ICU patients for improving antibiotic administration. Procalcitonin (PCT) though limited was superior to earlier biomarkers. Today, most of the benefit of using PCT in ICU patients is to decrease unnecessarily long courses of antibiotic therapy, rather than an improved diagnostic ability in determining which patients have active infectionviii, as PCT does not detect the earliest signs of sepsis. Therefore, it remains difficult to differentiate sepsis from other non-infectious systemic inflammatory syndromes, and there has been a continuous search for better sepsis biomarkers.

CD64 Sepsis Biomarker ix

Improved Sepsis diagnosis should be based on a marker that is specifically and rapidly activated upon infection. CD64 is constitutively expressed on the cell surface of PMNs and monocytes, but at low levels during the absence of infection. Upon invasion of a pathogen into the circulation, at a very early step of the immune host response, the expression level of CD64 on neutrophils increases dramatically. In addition, CD64 is negligibly expressed on neutrophils in the healthy state (<2,000 molecules per cell) resulting in a low false positive rate. CD64 has high specificity as its expression is not significantly elevated in malignancy of myeloid cells (CML, MPD, MDS), any drug therapy (other than cytokines), clinical conditions with localized tissue damage, pregnancy and auto-immune disorders.

The value of CD64 has been supported by numerous clinical studies as an assay for diagnosis of bacterial infection and sepsis. Measurement of CD64 expression is superior to other common tests (CRP, PCT, leukocyte count) for sensitivity & specificityx.

LeukoDx has in-licensed Leuko64 from Trillium diagnostics, ME, USA, for cartridge-based point-of-case diagnostic use. Because the biomarker measures neutrophil activation (which occurs 3–4 hours after infection), the CD64 marker is more rapid and more specific than other markers used to date to diagnose sepsis, and therefore having better power as a monitoring and prognostic marker.

 

Clinical Evaluation of CD64 Sepsis Biomarker

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The CD64 biomarker, has been validated in conventional FACs machines in numerous clinical studies as an assay for diagnosis of bacterial infection and sepsis.

CD64 & PCT : Gibot, S., American Jour of Respiratory & Critical Care Medicine, 2012 

  • CD64, PCT and sTREM-1 assessed for diagnosing sepsis in 300 critically ill patients
  • The best ROC curve obtained for the CD64 index - AUC 0.95

 

 CD64 & CRP : Dimoula A. Clin Infect Dis, 2014

  • CD64 & CRP were measured within 24 hours of admission in 468 ICU patients4
  • Septic patients had higher CD64 than non-septic pts (p < .001)
  • A cutoff admission CD64 expression identified sepsis with a sensitivity of 89% and specificity of 87%
  • When combining CRP and CD64 expression, sepsis was ruled out with a probability of 99%
  • In non-septic patients, an increase in CD64 expression predicted ICU-acquired infection

 

CD64 & WBC : Icardi, M., Journal of Clinical Microbiology, 2009

  • CD64 indices were performed in tandem with blood cultures from 109 patients
  • A CD64 index of >1.19 had a sensitivity and specificity for infection of 94.6% and 88.7%, respectively, resulting in an AUC = 0.943

CD64 index provides simple and predictive testing for detection and monitoring of sepsis and bacterial infection in hospital patients”.

 

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 CD64 & CRP : Gerrits, J. H., Clinical Chemistry and Laboratory Medicine 2013

  • Polymorphic mononuclear neutrophils CD64 index for diagnosis of sepsis in postoperative surgical patients and critically ill patients.
  • The CD64 index demonstrated higher sensitivity and specificity than CRP, WBC count, neutrophilic and eosinophilic granulocyte count, and ESR.
  • A high CD64 index was found in septic intensive care patients, while a low CD64 index was observed in OC and SIRS patients, demonstrating that the CD64 index can be used for routine diagnostics in the ICU setting
  • ROC curve analysis demonstrated that the CD64 index showed high sensitivity (100 % ) and specificity (95 % )

 

 CD64 & PCT : Zeituoun A., Scand J Infect Dis, 2010 

  • 49 newborn infants who met the criteria of sepsis were subjected to sepsis evaluation, measurement of PCT, IL-10 levels andCD64 expression
  • CD64 had a maximal sensitivity of 92% and specificity of 71% at a cut-off value of 2.6%, AUC = 0.94

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To date, there are no reliable diagnostic tests for sepsis or follow up monitoring that can give results in a time frame to allow doctors to identify sepsis and direct the most appropriate treatment. Early detection of sepsis can save lives and reduce morbidity.

ii Outcomes of the surviving sepsis campaign in intensive care units in the USA and Europe: a prospective cohort study. The Lancet Infectious Diseases, 2012; 12(12), 919.
iii http://lumibyte.eu/medical/sepsis-diagnosis/
iv International Organizations Declare Sepsis a Medical Emergency. Issued by an expert panel representing 20 adult and pediatric intensive care societies, October 4th 2010. 2010
v Kumar G, Kumar N, Taneja A, Kaleekal T, Tarima S, McGinley E, Jimenez E, Mohan A, Khan RA, Whittle J, Jacobs E, Nanchal R. Nationwide trends of severe sepsis in the 21st century (2000-2007). Chest, 2011. 140(5): p. 1223-31.
vi Torio CM (AHRQ), Andrews RM (AHRQ). National Inpatient Hospital Costs: The Most Expensive Conditions by Payer, 2011. HCUP Statistical Brief #160. August 2013
vii Rossaint R, Rossaint J: Sepsis: A Challenge for Politicians, Researchers, and Clinicians. Nova Acta Leopoldina NF 117, Nr. 395, 11–18 (2013)
viii Bouadma L. PRORATA trial. Lancet. 2010;375:463-74
ix CD64 is an Fc γ R1 cell surface marker on neutrophilic granulocytes, which binds IgG antibodies that facilitate bacterial opsonization and phagocytosis. CD64 is constitutively expressed on neutrophils, but at low levels during the absence of infection. During infection, CD64 expression is strongly upregulated on neutrophils. This regulation is under the control of inflammatory cytokines, such as interleukin (IL)-12 and interferon (IFN)- γ , and granulocyte colony stimulating factor (G-CSF).
x Hoffmann JJ. Biochemai Medica 2011;21:282-90