Cell Mediated Immune Response and Viral Load Testing: Two complimentary tools for efficient CMV monitoring

Transcription

1 Cell Mediated Immune Response and Viral Load Testing: Two complimentary tools for efficient CMV monitoring Nov 28, 2013 Dr. Christian Stöckigt Associate Director, Medical & Scientific Affairs EMEA

2 QuantiFERON-CMV - Introduction To establish QuantiFERON-CMV Major advance in (QFCMV) the management as the primary of CMV utility in the measurement disease risk in of transplant cytomegalovirus recipients. (CMV) specific cellular immunity, and Allows physicians to monitor a person s risk of The artus cytomegalovirus CMV QS-RGQ (CMV) kit as infection the primary and disease molecular utility to be used in the quantitative detection of cytomegalovirus May predict DNA which (using transplant real time recipients PCR), are at increased risk of CMV disease after their with both transplant to be used surgery. jointly in the management of cytomegalovirus May assist clinicians (CMV) infection/disease, the therapeutic in those cohorts management deemed to of be these at most patients risk of in developing a post-transplant CMV disease. (primarily solid organ transplant SOT, recipients).

3 CMV Diagnosis & Management Current Situation Two primary diagnostic approaches are used for the detection, and subsequent management, of CMV in transplant settings: 1. CMV Serology testing (IgG, IgM) a pre-transplant tool used to delineate CMV risk at the time of transplant (when measured in donor and recipient) 2. CMV Virus Isolation (on urine, blood, biopsy) routinely done in a pos-transplant setting via either: a. Detection of CMV DNA by PCR (Polymerase Chain Reaction) b. CMV antigenaemia testing CMV DNA PCR universally has become the current standard for the diagnosis of CMV infection, and the monitoring of anti-viral therapy within many transplant centers. Widely acknowledged that all current diagnostic strategies for CMV in SOT have variability in their sensitivity & lack internationally accepted references..

4 What is CMV Immune Monitoring? Immune Monitoring is a new clinical utility that involves measuring an individual s T- cell) response. Immune Monitoring of a transplant recipient s CMV specific T-cell response represents a new and emerging field within CMV management. Immune Monitoring of a transplant recipient s CMV specific T-cell response using QF-CMV will assist guiding therapeutic decision making Patients with poor T-cell responses could be targeted with longer courses of antiviral prophylaxis Patients with strong T-cell responses could be taken off costly (and toxic) antiviral prophylaxis with greater confidence

5 QuantiFERON-CMV Product Information Is one of a class of diagnostic tests called Interferon Gamma Release Assays (IGRA) Uses CMV-specific peptides designed that represent HLA Class I haplotypes covering >98% of human population Works by detecting any IFN-γ produced by a subject s CD8+ T-cells in response to the stimulation of these cells by the CMV specific peptides. Is a new immune monitoring utility to be used in the management of CMV in a transplant setting, offering different clinical information than PCR viral load testing. Is a complimentary - not competitive assay to CMV PCR testing

6 QuantiFERON-CMV Product Information QF-CMV uses 22 peptides simulating CD8+ specific epitopes of CMV proteins 22 Peptides CD8+ Specificity 20 HLA Class I 6 CMV Proteins >98% Coverage

7 QuantiFERON-CMV Test Procedure

8 QuantiFERON-CMV How results are calculated QF-CMV results are calculated following the detection (by ELISA) of IFN-γ within the plasma samples harvested from each of the 3 blood samples, & are reported as: "CMV Antigen" minus "Nil" "Mitogen" minus "Nil" QF-CMV Result QF-CMV Result Interpretation (IU/mL) (IU/mL) < Non Reactive Anti-CMV immunity NOT Detected 0.2 Any Reactive Anti-CMV immunity Detected < 0.2 < 0.5 Indeterminate Result indeterminate for CMV responsiveness An indeterminate result, in light of low Mitogen reading, may provide significant clinical information relating to a patient s immune function

9 QuantiFERON-CMV Interpretation of results The clinical benefit of monitoring T-cell responses is not necessarily the magnitude of any single test response, but whether the responses either rise, fall or stay constant over time. The trending of T-cell responses, over time post-transplant, is seen as the best predictor of immunity against CMV disease

10 Positioning QF-CMV against CMV viral load (PCR) QF-CMV represents an assay that is complimentary - not competitive - to all viral load testing (either by detection of CMV DNA by PCR or CMV antigenemia testing) Its use and positioning in relation to the CMV viral load testing by PCR) within a transplant setting, is yet to be clearly defined and is likely to evolve over time Both tests (QF-CMV and CMV PCR) are more than likely to be done as a pairing, with current viral load testing time points likely to remain unchanged.. The results of each test, in combination, will assist clinicians significantly in their: Therapeutic decision-making & ongoing management of their transplant recipients Understanding of the clinical value that each test will be able to provide on their own, and as a combination

11 Positioning QF-CMV against CMV viral load (PCR) CMV PCR viral load testing currently provides clinicians with an insight into some of the unique properties of the CMV virus, alternatively QF-CMV testing now provides clinicians with an insight into the capability of the transplant recipient s immune system to mount a response to the CMV virus. Viral factors able to be analyzed by PCR testing volume of viral load viral replication dynamics immune evasion capability Host factors now able to be analyzed by QF-CMV testing CD8+ T-cell capability exogenous immunosuppression

12 Potential QF-CMV Testing time-points The volume/frequency of Immune Monitor testing of a SOT recipient (using QF-CMV) has yet to be formally established, but will likely be dependent on: Which of the 2 principal CMV Management strategies transplant centres may use i.e.: 1. The universal prophylactic approach as mainly used in the US, or 2. The pre-emptive prophylactic approach as mainly used in Europe The health of the transplant recipient during the first 12 months post-transplant The length of time required for a transplant recipient to either recover, or develop, their protective anti CMV cellular immunity

13 How QF-CMV testing will improve pre-emptive prophylactic strategies It is well documented that ( 50%) of transplant recipients with asymptomatic low-level viremia (as diagnosed by VL testing using PCR) will clear their viremia spontaneously, without the need for antiviral therapy As a resuit, a significant refinement of pre-emptive protocols could be made with the addition of immune monitor (QF-CMV) testing to current viral load testing Immune monitor (QF-CMV) testing will assist in identifying which transplant recipients with low-level viremia could simply continue to be followed closely, and which patients should commence anti-viral treatment. Parallel CMV testing using PCR viral load & QF-CMV will result in: more rational anti-viral use, with. a potential decrease in anti-viral over-treatment of transplant recipients, meaning a reduction in unnecessary toxicity and associated healthcare cost.

14 Potential QF-CMV Testing time-points (EU-ROW) Possible QF-CMV testing time points in a pre-emptive prophylactic setting (the CMV Management strategy that transplant centres in Europe and the ROW usually follow): Every few days for a week or two, following the first evidence of asymptomatic low level viremia diagnosed by CMV PCR using in-house established test thresholds Such a strategy would determine which transplant recipients may be at real increased risk of symptomatic CMV infection (based on the absence of CMV immunity) & thus be candidates to commence anti-viral prophylactic therapy Every few days for a week or two, during and/or following the administration of any anti-viral prophylaxis Such a strategy would determine which transplant recipients may be at a lower risk of developing symptomatic CMV infection (based on the recovery of their CMV immunity) during their prophylaxis, and thus be candidates to be confidently taken off, what would be unnecessary (costly and toxic) anti-viral prophylactic therapy.

15 QF-CMV inclusion in International Consensus Guidelines International Consensus Guidelines on the Management of CMV in Solid Organ Transplants Kotton CN, et al. (2010) Transplantation Summary: First ever international guidelines relating to the diagnosis and management of CMV in a SOT setting Indicate that the use of the immune monitoring of CMV-specific T-cell responses Predict those individuals at increased risk of CMV disease post-transplant Be useful in guiding prophylaxis and pre-emptive therapies.

16 QF-CMV inclusion in International Consensus Guidelines International Consensus Guidelines on the Management of CMV in Solid Organ Transplants Kotton CN, et al. (2010) Transplantation Key Findings: The guidelines suggest that an ideal immune monitoring assay should assess the quantity and function of a transplant recipient s CD4+ & CD8+ T cells, and that such an assay should also: Be able to measure interferon-gamma (IFN-γ) Be simple to perform, cost-effective, and reproducible Have a rapid turnaround time Allow for specimens to be easily shipped to specialized referral laboratories The guidelines reinforce that: QF-CMV is a simple blood test that meets virtually all the criteria an ideal immune monitoring assay should have (it does not assess the quantity CD4+ T cells) QF-CMV the only standardized, commercially-available immune monitoring assay, specific for CMV.

17 QF-CMV inclusion in International Consensus Guidelines Updated international consensus guidelines on the management of cytomegalovirus in solidorgan transplantation Kotton CN, et al. (2013) Transplantation Summary: QuantiFERON-CMV has been clinically evaluated in transplant patients at high risk of CMV and shown to be predictive of disease. A negative QuantiFERON-CMV test before transplantation may aid in predicting viremia after transplantation and the dynamics of T-cell responses may be used as a monitoring tool in pre-emptive management. In a small cohort of transplant recipients with low-level CMV DNAemia, a QF-CMV positive assay was predictive of spontaneous clearance. QF-CMV test interpretation is unclear if a post transplantation patient does not respond to the mitogen control; this may be a marker for global immunosuppression and has been associated with a subsequent higher incidence of CMV disease.

18 QF-CMV: Intended Use & Benefits QF-CMV measures an individual s CMV-specific cellular immunity, & thus enables the monitoring of anti-cmv immunity in persons at risk of developing CMV disease QF-CMV is not a direct test for determining CMV infection and should not solely be used to exclude CMV infection QF-CMV offers different clinical information to that offered by PCR viral load testing QF-CMV will assist clinicians: Predict the risk of late-onset CMV disease (new and recurrent) Guide therapeutic decision making Improve Patient health

19 QUESTIONS?