Thiopurine methyltransferase (TPMT) is an enzyme involved in the metabolism of thiopurine drugs such as azathioprine. TPMT genotyping or measurement of enzyme activity prior to treatment enables prediction of those individuals most at risk of myelotoxicity in whom these drugs should be avoided or used in reduced doses.
by Dr Joshua Ryan, Christiaan Sies and Associate Professor Chris Florkowski
Background
Thiopurine drugs azathioprine (AZA) and 6-mercaptopurine (6-MP) are widely used as steroid-sparing agents in autoimmune diseases such as inflammatory bowel disease (IBD), autoimmune hepatitis, rheumatoid arthritis as well as following organ transplantation and in leukaemia [1, 2]. In the body, AZA is rapidly converted, largely non-enzymatically, into 6-MP which is subsequently metabolized to the active compound 6-thioguanine (6-TG) by several sequential enzymes starting with hypoxanthine guanine phosphoribosyltransferase (HGPRT) (Fig. 1) [1].
6-TG is a nucleotide analogue that is incorporated into DNA and RNA thereby interfering with cellular function and protein synthesis and also blocks the cellular signalling protein Rac 1, resulting in T cell apoptosis [3]. Although these mechanisms underlie the therapeutic action of thiopurine drugs, excessive and toxic levels of 6-TG however, can cause myelosuppression and life-threatening leukopenia [3]. Two additional enzymes xanthine oxidase (which normally converts xanthine to uric acid and is inhibited by the gout treatment drug allopurinol) and thiopurine methyltransferase (TPMT; an enzyme whose natural substrate is unknown) play important roles in thiopurine drug metabolism, providing alternative pathways that convert 6-MP into the inactive metabolites 6-thiouric acid and 6-methyl-mercaptopurine (6-MMP), respectively (Fig. 1) [1, 3].
Any factors that reduce the activity of these pathways, either acquired (e.g. allopurinol) or inherited (e.g. TPMT deficiency) can result in a greater proportion of the drug being metabolized to active metabolites, conferring increased risk of toxicity.
TPMT deficiency, pathophysiology and clinical effects
The activity of this enzyme in the body is co-dominantly inherited and the TPMT gene is on chromosome 6 [4]. The majority of the population (89–92%) inherit two normally functioning copies of the gene (allele designated TMPT*1). A smaller proportion (8–11%) inherit one deficiency allele (of which 29 have been identified) giving low TPMT activity and rarely, 0.3% of individuals are homozygous for the deficiency alleles resulting in virtually no TMPT activity [1, 3].
The TPMT*3A variant is a double mutant allele (G460A on exon 7 and A719G on exon 10), TPMT*3C has the same A719G mutation on exon 10 mutation as for TPMT*3A and TPMT*2 has a G238C point mutation on exon 5 [3]. Together, alleles TPMT*2, *3A and *3C account for the majority (up to 95%) of deficiency alleles that are seen in Caucasian, Asian and African-American populations [3, 5]. The resulting trimodal distribution of enzyme levels (low, intermediate, normal) was demonstrated in our local population in a study of 407 patient samples referred to Canterbury Health Laboratories from throughout New Zealand over a 2-year period (Fig. 2) [6]. Patients with reduced red blood cell (RBC) TPMT activity below 12units/mL RBCs went on to have TPMT genotyping for three common deficiency alleles (*2, *3A, *3C) [6]. The three groups of patients identified had enzyme activity that reflected the underlying genotype (i.e. normal TPMT, deficiency allele heterozygotes and deficiency allele homozygotes) although there was some overlap in enzyme activities seen between the normal and heterozygous deficiency patients (Fig. 2).
Patients with inherited TPMT deficiency (i.e. homozygous for deficiency alleles) are at high risk of potentially fatal myelosuppression, as in these patients a greater proportion of the thiopurine drug is metabolized to active metabolites resulting in bone marrow toxicity. In these patients AZA should be avoided or the dose markedly reduced [1, 3]. Heterozygotes for deficiency alleles also have increased rates of adverse effects and in these patients, some dose reduction (by 50–67%) is recommended [3].
Enzyme activity measurement
TPMT enzyme activity may be measured in RBCs prior to commencing the thiopurine drugs to identify TPMT status (‘phenotype’) and to help guide drug and dose decisions. Traditional enzymatic methods used a 6-MP substrate and radiolabelled methyl donor and the radiolabelled product (6-MMP) was measured by scintillation counting [1, 6]. More recent methods have avoided the use of radiolabelled compounds by using HPLC-UV or mass spectrometry for product detection [3]. Patients found to have low levels on phenotyping may be confirmed using genetic testing of TPMT. In-house studies on a local population found TPMT activity levels ≥10.7 units/mL RBC excluded the presence of a deficiency allele (normal reference interval 9.3–17.6 units/mL RBC) [6]. It should be noted, however that reporting units may vary between laboratories (e.g. reported per mL of RBC or per g of Hb to adjust for variations in hematocrit) and results should be interpreted relative to lab-specific reference intervals [4].
Measurement of RBC TPMT enzyme activity, however, has some important caveats. For example, TPMT activity is not reliable in patients who have received a blood transfusion in the preceding 120 days (i.e. RBC average life span) due to interference from donor RBC TPMT [3]. Chronic renal failure may elevate TPMT activity and higher levels are seen in pre-dialysis samples compared with those collected following dialysis [1,4]. Differences have also been reported with other diseases (e.g. IBD, autoimmune hepatitis, pemphigus) but the differences are small and clinically unimportant [4]. Various drug compounds can affect TPMT activity causing a decrease (e.g. sulfasalazine) or increase (e.g. methotrexate, trimethoprim) of in vitro activity however, in assays with a RBC wash step the interfering compounds may be largely removed [4].
In our laboratory, samples are collected in EDTA whole blood and stored refrigerated (or chilled with an ice pack for transport). A previous local study of samples referred to Canterbury Health Laboratories over 8 years (n=6348) found delay in analysis had a small but significant reduction on TPMT activity of 0.26 units/mL RBC for each additional day prior to analysis [2]. Another published review found TMPT activity to be relatively stable at room temperature or refrigerated for 7 days, although may be reduced in some disease states such as leukaemia [4].
The role of genotyping
Genotyping may also be used to assess TPMT status prior to commencing AZA or 6-MP either alone or commonly to confirm low enzyme activity. It has the advantage of not being affected by blood transfusions and is less affected by pre-analytical factors. The limitation is that only common deficiency alleles are tested for (e.g. TPMT*2, *3A, *3C) and rare deficiency alleles will be missed using genotyping alone [1]. Enzyme activity measurement may also identify those patients who have ultra-high TPMT activity (up to 2% of patients) and who may require higher than usual doses, information that routine genotyping alone would not provide [3].
The place of 6-TG monitoring and other investigations
Once treatment has been initiated (ideally following TPMT assessment), ongoing treatment is usually monitored by measurement of the metabolite 6-TG, for which therapeutic ranges have been suggested – for example RBC 6-TG >235 pmol/8×108 cells is associated with maximum efficacy in IBD [3]. The metabolite 6-MMP is usually monitored together with 6-TG in order to differentiate non-compliance or inadequate dose (i.e. low 6-TG and 6-MMP), from those patients where AZA is preferentially metabolized to 6-MMP (i.e. high 6-MMP and low 6–TG) [3]. In the latter scenario, increasing the dose can lead to further elevation of RBC 6-MMP and values >5700 pmol/ 8×108 cells are associated with hepatotoxicity [3].
All of the above, however does not obviate the need for patients on thiopurine drugs to undergo regular monitoring of routine blood tests (e.g. full blood count, liver function tests) to allow early detection of the most serious adverse effects of myelosuppression and liver dysfunction [3, 5]. This monitoring in required regardless of TPMT status and especially given that TMPT deficiency does not predict all cases of myelosuppression in patients on these medications [3].
Recommended ractice
The US Food and Drug Administration (FDA) and prescribing information for AZA and 6-MP recommend assessing TPMT status with genotyping or phenotyping prior to starting treatment with thiopurine drugs [7]. There is, however considerable variation in what guidelines recommend in routine practice regarding TPMT and indeed, some systematic reviews have concluded that there is insufficient evidence for TPMT testing in chronic inflammatory diseases [5]. Based on a frequency of 1 in 300 for homozygous deficiency, we calculated that in New Zealand with an assay cost of $57.75 per assay (in 2005), this would equate to a cost of $17,250 per potentially fatal episode averted [6]. Similar calculations in the United Kingdom have indicated that the costs per quality adjusted life-year (QALY) gained are well within acceptable thresholds [3].
Future developments and conclusion
As with many other drugs, the metabolism of AZA and 6-MP is complex and information is accumulating on other inherited and acquired factors contributing to the adverse effects of these medications. For example, inherited differences in other enzymes involved in their metabolism such as xanthine oxidase and inosine triphosphate pyro-phosphohydrolase (ITPase) may have a role and further study on these mechanisms is required [3].
In conclusion, TPMT provides a paradigm where testing that provides information about the genetic makeup of an individual (directly or indirectly through enzyme testing) enables important guidance on drug dosing, with the potential to avoid serious side-effects. Measuring TPMT activity in RBCs prior to starting AZA or 6-MP (with confirmatory genotyping) is a simple yet effective way to detect those with TPMT deficiency who are at particular risk of bone marrow toxicity, although ongoing monitoring with routine bloods is required in all patients to identify serious drug adverse effects.
References
1. Gearry RB, Barclay ML, et al. Thiopurie methyltransferase and 6-thioguanine nucleotide measurement: early experience of use in clinical practice. IMJ 2005; 35: 580–585.
2. Van Egmond R, Barclay ML, et al. Preanalytical stringency: what factors may confound interpretation of thiopurine S-methyl transferase enzyme activity. Ann Clin Biochem. 2013; 50: 479–484.
3. Ford LT, Berg JD. Thiopurine S-methyltransferase (TPMT) assessment prior to starting thiopurine drug treatment; a pharmacogenomic test whose time has come. J Clin Pathol. 2010; 63: 288–295.
4. Loit E, Tricco AC, et al. Pre-analytic and analytic sources of variation in thiopurine methyltransferase activity measurement in patients prescribed thiopurine-based drugs: a systematic review. Clin Biochem. 2011; 44: 751–757.
5. Booth RA, Ansari MT, et al. Ann Int Med. 2011; 154: 814–823.
6. Sies C, Florkowski C, et al. Measurement of thiopurine methyl transferase activity guides dose-initiation and prevents toxicity from azathioprine. NZMJ 2005; 118: U1324.
7. Nguyen CM, Mendes MAS, Ma JD. Thiopurine Methyltransferase (TPMT) genotyping to predict myelosuppression risk. PLoS Curr. 2011; 3:RRN1236.
The authors
Joshua Ryan MB MAACB FRCPA, Christiaan Sies MSc, Chris Florkowski* MD MRCP(UK) FRACP FRCPA
Canterbury Health Laboratories, Christchurch, New Zealand
*Corresponding author
E-mail: Chris.florkowski@cdhb.health.nz
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, /in Featured Articles /by 3wmediaThiopurine methyltransferase: a paradigm of pharmacogenetics
, /in Featured Articles /by 3wmediaThiopurine methyltransferase (TPMT) is an enzyme involved in the metabolism of thiopurine drugs such as azathioprine. TPMT genotyping or measurement of enzyme activity prior to treatment enables prediction of those individuals most at risk of myelotoxicity in whom these drugs should be avoided or used in reduced doses.
by Dr Joshua Ryan, Christiaan Sies and Associate Professor Chris Florkowski
Background
Thiopurine drugs azathioprine (AZA) and 6-mercaptopurine (6-MP) are widely used as steroid-sparing agents in autoimmune diseases such as inflammatory bowel disease (IBD), autoimmune hepatitis, rheumatoid arthritis as well as following organ transplantation and in leukaemia [1, 2]. In the body, AZA is rapidly converted, largely non-enzymatically, into 6-MP which is subsequently metabolized to the active compound 6-thioguanine (6-TG) by several sequential enzymes starting with hypoxanthine guanine phosphoribosyltransferase (HGPRT) (Fig. 1) [1].
6-TG is a nucleotide analogue that is incorporated into DNA and RNA thereby interfering with cellular function and protein synthesis and also blocks the cellular signalling protein Rac 1, resulting in T cell apoptosis [3]. Although these mechanisms underlie the therapeutic action of thiopurine drugs, excessive and toxic levels of 6-TG however, can cause myelosuppression and life-threatening leukopenia [3]. Two additional enzymes xanthine oxidase (which normally converts xanthine to uric acid and is inhibited by the gout treatment drug allopurinol) and thiopurine methyltransferase (TPMT; an enzyme whose natural substrate is unknown) play important roles in thiopurine drug metabolism, providing alternative pathways that convert 6-MP into the inactive metabolites 6-thiouric acid and 6-methyl-mercaptopurine (6-MMP), respectively (Fig. 1) [1, 3].
Any factors that reduce the activity of these pathways, either acquired (e.g. allopurinol) or inherited (e.g. TPMT deficiency) can result in a greater proportion of the drug being metabolized to active metabolites, conferring increased risk of toxicity.
TPMT deficiency, pathophysiology and clinical effects
The activity of this enzyme in the body is co-dominantly inherited and the TPMT gene is on chromosome 6 [4]. The majority of the population (89–92%) inherit two normally functioning copies of the gene (allele designated TMPT*1). A smaller proportion (8–11%) inherit one deficiency allele (of which 29 have been identified) giving low TPMT activity and rarely, 0.3% of individuals are homozygous for the deficiency alleles resulting in virtually no TMPT activity [1, 3].
The TPMT*3A variant is a double mutant allele (G460A on exon 7 and A719G on exon 10), TPMT*3C has the same A719G mutation on exon 10 mutation as for TPMT*3A and TPMT*2 has a G238C point mutation on exon 5 [3]. Together, alleles TPMT*2, *3A and *3C account for the majority (up to 95%) of deficiency alleles that are seen in Caucasian, Asian and African-American populations [3, 5]. The resulting trimodal distribution of enzyme levels (low, intermediate, normal) was demonstrated in our local population in a study of 407 patient samples referred to Canterbury Health Laboratories from throughout New Zealand over a 2-year period (Fig. 2) [6]. Patients with reduced red blood cell (RBC) TPMT activity below 12units/mL RBCs went on to have TPMT genotyping for three common deficiency alleles (*2, *3A, *3C) [6]. The three groups of patients identified had enzyme activity that reflected the underlying genotype (i.e. normal TPMT, deficiency allele heterozygotes and deficiency allele homozygotes) although there was some overlap in enzyme activities seen between the normal and heterozygous deficiency patients (Fig. 2).
Patients with inherited TPMT deficiency (i.e. homozygous for deficiency alleles) are at high risk of potentially fatal myelosuppression, as in these patients a greater proportion of the thiopurine drug is metabolized to active metabolites resulting in bone marrow toxicity. In these patients AZA should be avoided or the dose markedly reduced [1, 3]. Heterozygotes for deficiency alleles also have increased rates of adverse effects and in these patients, some dose reduction (by 50–67%) is recommended [3].
Enzyme activity measurement
TPMT enzyme activity may be measured in RBCs prior to commencing the thiopurine drugs to identify TPMT status (‘phenotype’) and to help guide drug and dose decisions. Traditional enzymatic methods used a 6-MP substrate and radiolabelled methyl donor and the radiolabelled product (6-MMP) was measured by scintillation counting [1, 6]. More recent methods have avoided the use of radiolabelled compounds by using HPLC-UV or mass spectrometry for product detection [3]. Patients found to have low levels on phenotyping may be confirmed using genetic testing of TPMT. In-house studies on a local population found TPMT activity levels ≥10.7 units/mL RBC excluded the presence of a deficiency allele (normal reference interval 9.3–17.6 units/mL RBC) [6]. It should be noted, however that reporting units may vary between laboratories (e.g. reported per mL of RBC or per g of Hb to adjust for variations in hematocrit) and results should be interpreted relative to lab-specific reference intervals [4].
Measurement of RBC TPMT enzyme activity, however, has some important caveats. For example, TPMT activity is not reliable in patients who have received a blood transfusion in the preceding 120 days (i.e. RBC average life span) due to interference from donor RBC TPMT [3]. Chronic renal failure may elevate TPMT activity and higher levels are seen in pre-dialysis samples compared with those collected following dialysis [1,4]. Differences have also been reported with other diseases (e.g. IBD, autoimmune hepatitis, pemphigus) but the differences are small and clinically unimportant [4]. Various drug compounds can affect TPMT activity causing a decrease (e.g. sulfasalazine) or increase (e.g. methotrexate, trimethoprim) of in vitro activity however, in assays with a RBC wash step the interfering compounds may be largely removed [4].
In our laboratory, samples are collected in EDTA whole blood and stored refrigerated (or chilled with an ice pack for transport). A previous local study of samples referred to Canterbury Health Laboratories over 8 years (n=6348) found delay in analysis had a small but significant reduction on TPMT activity of 0.26 units/mL RBC for each additional day prior to analysis [2]. Another published review found TMPT activity to be relatively stable at room temperature or refrigerated for 7 days, although may be reduced in some disease states such as leukaemia [4].
The role of genotyping
Genotyping may also be used to assess TPMT status prior to commencing AZA or 6-MP either alone or commonly to confirm low enzyme activity. It has the advantage of not being affected by blood transfusions and is less affected by pre-analytical factors. The limitation is that only common deficiency alleles are tested for (e.g. TPMT*2, *3A, *3C) and rare deficiency alleles will be missed using genotyping alone [1]. Enzyme activity measurement may also identify those patients who have ultra-high TPMT activity (up to 2% of patients) and who may require higher than usual doses, information that routine genotyping alone would not provide [3].
The place of 6-TG monitoring and other investigations
Once treatment has been initiated (ideally following TPMT assessment), ongoing treatment is usually monitored by measurement of the metabolite 6-TG, for which therapeutic ranges have been suggested – for example RBC 6-TG >235 pmol/8×108 cells is associated with maximum efficacy in IBD [3]. The metabolite 6-MMP is usually monitored together with 6-TG in order to differentiate non-compliance or inadequate dose (i.e. low 6-TG and 6-MMP), from those patients where AZA is preferentially metabolized to 6-MMP (i.e. high 6-MMP and low 6–TG) [3]. In the latter scenario, increasing the dose can lead to further elevation of RBC 6-MMP and values >5700 pmol/ 8×108 cells are associated with hepatotoxicity [3].
All of the above, however does not obviate the need for patients on thiopurine drugs to undergo regular monitoring of routine blood tests (e.g. full blood count, liver function tests) to allow early detection of the most serious adverse effects of myelosuppression and liver dysfunction [3, 5]. This monitoring in required regardless of TPMT status and especially given that TMPT deficiency does not predict all cases of myelosuppression in patients on these medications [3].
Recommended ractice
The US Food and Drug Administration (FDA) and prescribing information for AZA and 6-MP recommend assessing TPMT status with genotyping or phenotyping prior to starting treatment with thiopurine drugs [7]. There is, however considerable variation in what guidelines recommend in routine practice regarding TPMT and indeed, some systematic reviews have concluded that there is insufficient evidence for TPMT testing in chronic inflammatory diseases [5]. Based on a frequency of 1 in 300 for homozygous deficiency, we calculated that in New Zealand with an assay cost of $57.75 per assay (in 2005), this would equate to a cost of $17,250 per potentially fatal episode averted [6]. Similar calculations in the United Kingdom have indicated that the costs per quality adjusted life-year (QALY) gained are well within acceptable thresholds [3].
Future developments and conclusion
As with many other drugs, the metabolism of AZA and 6-MP is complex and information is accumulating on other inherited and acquired factors contributing to the adverse effects of these medications. For example, inherited differences in other enzymes involved in their metabolism such as xanthine oxidase and inosine triphosphate pyro-phosphohydrolase (ITPase) may have a role and further study on these mechanisms is required [3].
In conclusion, TPMT provides a paradigm where testing that provides information about the genetic makeup of an individual (directly or indirectly through enzyme testing) enables important guidance on drug dosing, with the potential to avoid serious side-effects. Measuring TPMT activity in RBCs prior to starting AZA or 6-MP (with confirmatory genotyping) is a simple yet effective way to detect those with TPMT deficiency who are at particular risk of bone marrow toxicity, although ongoing monitoring with routine bloods is required in all patients to identify serious drug adverse effects.
References
1. Gearry RB, Barclay ML, et al. Thiopurie methyltransferase and 6-thioguanine nucleotide measurement: early experience of use in clinical practice. IMJ 2005; 35: 580–585.
2. Van Egmond R, Barclay ML, et al. Preanalytical stringency: what factors may confound interpretation of thiopurine S-methyl transferase enzyme activity. Ann Clin Biochem. 2013; 50: 479–484.
3. Ford LT, Berg JD. Thiopurine S-methyltransferase (TPMT) assessment prior to starting thiopurine drug treatment; a pharmacogenomic test whose time has come. J Clin Pathol. 2010; 63: 288–295.
4. Loit E, Tricco AC, et al. Pre-analytic and analytic sources of variation in thiopurine methyltransferase activity measurement in patients prescribed thiopurine-based drugs: a systematic review. Clin Biochem. 2011; 44: 751–757.
5. Booth RA, Ansari MT, et al. Ann Int Med. 2011; 154: 814–823.
6. Sies C, Florkowski C, et al. Measurement of thiopurine methyl transferase activity guides dose-initiation and prevents toxicity from azathioprine. NZMJ 2005; 118: U1324.
7. Nguyen CM, Mendes MAS, Ma JD. Thiopurine Methyltransferase (TPMT) genotyping to predict myelosuppression risk. PLoS Curr. 2011; 3:RRN1236.
The authors
Joshua Ryan MB MAACB FRCPA, Christiaan Sies MSc, Chris Florkowski* MD MRCP(UK) FRACP FRCPA
Canterbury Health Laboratories, Christchurch, New Zealand
*Corresponding author
E-mail: Chris.florkowski@cdhb.health.nz
Performance studies indicate suitability of VERIS* for routine lab applications
, /in Featured Articles /by 3wmediaBeckman Coulter’s VERIS Molecular Diagnostic (MDx) System* is a fully automated system for quantitative and qualitative analysis of molecular targets. It integrates sample introduction, nucleic acid extraction, reaction setup, real-time PCR amplification and detection, and results interpretation. Abstracts of studies presented as posters at the recent European Congress of Clinical Microbiology and Infectious Diseases (ECCMID) in Barcelona highlighted the suitability of the system and its assays for use in the routine laboratory. Three of these abstracts appear below.
VERIS Molecular Diagnostic System sample-to-sample crossover contamination study
Summary
Sample carry-over and cross-contamination present a high risk for the laboratory. VERIS was developed to have a false positive rate due to cross contamination of less than 1 in 500 tests with an overall design goal of zero. This study involved several stages: to assess the sample-to-sample contamination rate using a real-time PCR assay and then characterize potential sources of contamination. System modifications were then to be developed to resolve any carry-over and cross-contamination and the system then retested.
Method and Results
Contamination characterization was performed by swabbing areas of the instrument before and after running a series of high concentration level positive samples to determine potential sources of contamination. Twenty high positive Cytomegalovirus (CMV) spiked samples at a concentration of 1×1010 IU/mL were used in this testing. A total of 27 high risk areas on the instrument were evaluated. High risk areas were defined as areas on the system where liquid handling occurs and where potential splashing of sample or reagents can occur. The swabs were placed in the TE buffer and then processed on the VERIS system. Swab assessments identified several areas where splashing and contamination of high positive samples was occurring, with the potential to contaminate a future sample.**
This resulted in several modifications to the liquid handling parameters and motor speeds to eliminate the potential for sample-to-sample contamination. Swab testing was used to verify the effectiveness of the modifications. The study concluded that accurate results for true negative samples were now being shown, with no detectable carryover and contamination from high positive to negative samples. This was true when the concentration of CMV target in the samples was above clinical levels and the frequency of high positives in the sample population exceeded 30%.
Cytomegalovirus (CMV) viral load assay for the VERIS MDx System
Summary
The initial assay menu includes the VERIS Cytomegalovirus (CMV) Assay*, intended for use in conjunction with clinical presentation and other laboratory markers as an aid in monitoring CMV viral load and for the detection of virus reactivation. This study reported on performance in key analytical and clinical measures.
Method and Results
137 paired samples tested on both the VERIS CMV Assay and the Roche COBAS AmpliPrep/COBAS TaqMan CMV Test were used to demonstrate method comparison in accordance with CLSI EP9-A2. 287 specimens were tested to demonstrate the clinical specificity of the assay.
Assay measuring interval: the assay is linear for human CMV with a lower limit of quantitation (LLQ) of 120 IU/mL and an upper limit of quantitation (ULQ) of 10,000,000 IU/mL. A nine member panel of the CMV AD169 reference strain demonstrated a linear range of 159 to 13,400,000 IU/mL (2.20-7.13 Log IU/mL). A four-member panel of the 1st WHO International Standard for Human Cytomegalovirus (HCMV) (NIBSC 09/162) demonstrated a linear range from 120 and 10,000 IU/mL (2.08-4.00 Log IU/mL)
Precision: demonstrated a total (within-run and between-run) standard deviation of less than 0.15 Log IU/mL across its linear range.
Sensitivity: The VERIS CMV Assay was shown to have a Limit of Detection (LoD) of 30 IU/mL (1.48 Log IU/mL) across all subtypes tested.
Performance evaluation of the Beckman Coulter VERIS Cytomegalovirus Assay on the VERIS MDx System
Summary
Another study assessed the VERIS CMV assay for reproducibility and specificity, comparing it with the Roche COBAS AmpliPrep/COBAS TaqMan CMV test. In immune-compromised individuals, the activation of the latent virus, is a significant cause of morbidity and mortality. Real-time polymerase chain reaction (PCR) assays offer the ability to diagnose active infection and monitor those individuals at risk.
Method and Results
Using paired plasma samples, total assay imprecision was
≤ 4.6% CV with the SD ≤0.14. Clinical specificity with negative samples was 100% with a lower bound of the 95% CI = 98.7%. It had comparable recoveries to the Roche assay with a Passing-Bablock regression equation of VERIS=0.30+1.00 (Roche), r=0.88 and n=130.
*Not for sale or distribution in the U.S.; not available in all markets.
**References available on request
Fostering Georgia’s thriving hematology sector
, /in Featured Articles /by 3wmediaThe state of Georgia is committed to supporting and growing the booming life science industry. By continually investing in its people, resources and solutions that meet companies’ unique business needs, Georgia is becoming a leader in the hematology and immunology sector.
When it comes to the study of blood and curing blood-related diseases, access to the right research, qualified talent and effective cold chain logistics is imperative to solving tomorrow’s health challenges.
These are a few of the many reasons Baxter International’s $1.3 billion (€0.96 billion) plasma fractionation plant, the America Red Cross’ Biomedical Services, the second largest blood processing facility in the world by volume, and Qualtex Laboratories, the United States’ largest independent testing lab for blood and plasma products, have chosen Georgia to call home.
Georgia is well equipped to support hematology companies and advanced research initiatives in treating and curing serious illnesses. In fact, Georgia’s robust hematology sector accounts for 21 percent of the state’s life science workforce.
Talent and training
One of the vital resources that companies in the hematology sector are finding in Georgia is access to the most innovative research and development, as well as the best and brightest talent. Georgia life science companies continue to take advantage of our world-class institutions and universities and the number one workforce training program in the nation, QuickStart.
In fact, EMSI ranks Georgia medical and health-related degrees as the No. 1 area of study in the region, and Georgia Tech’s biomedical/bioengineering programs are in the top five in the nation.
Emory University (Emory) has long been recognized for its expertise in cellular immunity and immune memory at the Emory Vaccine Center (EVC). EVC is one the largest and most comprehensive academic vaccine centres in the world. Nine in 10 HIV patients undergo lifesaving therapy that includes drugs that were created at Emory University.
Public-private partnerships
By connecting state resources such as the Centers for Disease Control and Prevention with companies and universities engaged in life science exploration, Georgia has created a dynamic and collaborative environment to support this booming industry.
The Atlanta Clinical & Translation Science Institute (ACTSI), a collaboration between Emory, the Georgia Institute of Technology (Tech) and the Morehouse School of Medicine, is solely focused on transforming scientific discovery into a positive impact on the community.
The Lam Lab, located at Emory and Tech, offers the ideal environment to foster integration between microtechnology development and experimental hematology and oncology practices.
The Georgia BioScience Training Center, a 50,000-square-foot facility dedicated to supporting research and technology transfer in the bioscience industry, will provide comprehensive, customized workforce training critical to the successful operations of bioscience and biomanufacturing industries. The Center will help train employees for Baxter’s $1 billion biomaufacturing plant in Covington, Ga.
Cold chain logistics
Supplying life-saving vaccines and treatments to the world would not be possible without Georgia’s extensive cold chain network. Being home to 75 facilities that have temperature-controlled and frozen storage capabilities, Georgia has built a strong value chain and an interconnected infrastructure to better meet the demands of the hematology sector. The Hartsfield-Jackson Atlanta International Airport houses a 32,000-square-foot Atlanta Perishables Center. The center is the only facility in the Southeast approved by the USDA to apply cold treatment, an alternative to methyl bromide.
Georgia Department of Economic Development www.georgia.org/hematology
Automated Chemiluminenscence Immunoassay
, /in Featured Articles /by 3wmediaTandem mass spectrometer LCMS-8040
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