L. Masae Kawamura, M.D. Senior Director, Medical and Scientific Affairs, Tuberculosis Clinician, San Francisco TB Clinic DISCLAIMER

Transcription

1 IGRA update QuantiFERON -TB Gold Plus (QFT-Plus) L. Masae Kawamura, M.D. Senior Director, Medical and Scientific Affairs, Tuberculosis Clinician, San Francisco TB Clinic October, 2018 DISCLAIMER I am employed by QIAGEN, manufacturer of QFT and other diagnostics, however the views expressed are my own and not necessarily the views of QIAGEN Global Tuberculosis Report 2017, WHO 1

2 Tuberculin skin test (TST) IGRA: ELISA IGRA example Manual placement, reading and data entry Results affected by BCG vaccine and NTM Two patient visits required, high no-show rate Significant inter-reader variability Poor surveillance tool Often no quality control after initial training Boosted reactions confound serial testing Can be fully automated (QFT-Plus) Highly specific, not affected by BCG Results with one patient visit No inter-reader variability (QFT-Plus) Electronic results (straight to EMR) Quality-assured laboratory NO boosting from serial IGRAs TST is a not patient or program centered assay, especially in the populations relevant to TB control 3 Evolution of ELISA IGRA Technology 1 st generation QuantiFERON -TB 2 nd generation QuantiFERON -TB Gold (liquid antigen) 3 rd generation QuantiFERON -TB Gold (QFT in tube) 4 th generation QuantiFERON -TB Gold Plus (QFT -Plus) 2001: FDA approval 2004: FDA approval 2007: FDA approval Measured cell-mediated immunity to tuberculin purified protein derivative (PPD) Breakthrough: TST becomes a blood test Liquid antigen version Antigens specific for M.tb with 99% specificity New benchmark: No cross reactivity with BCG Logistical advantage remote incubation New benchmark: Scalable and easily automated >1500 peer reviewed publicatoins >30 million tests sold Q4 2014: CE-IVD 2017: FDA approved New benchmark: Addition of patented CD8 antigens potential biomarker of intracellular TB burden New flexible blood draw options 4 2

3 QFT Publications prior to QFT-Plus ~1500 published studies with key articles showing important utility in testing high risk groups BCG-vaccinated Migrants to US HIV Biologics Pediatrics Pregnancy Contacts Risk of Progression End Stage Renal Gao L et al, Lancet Infect Dis Mar; 15(3): Epub 2015 Feb Howley MM et al. Pediatr Infect Dis J Aug 4. Painter JA et al. PLoS One Dec 19;8(12):e Riazi S et al. Allergy Asthma Proc May-Jun;33(3): Howley MM et al. Pediatr Infect Dis J Aug 4. Painter JA et al. PLoS One Dec 19;8(12):e Sorborg C et al. Eur Respir J Aug;44(2):540-3 Cheallaigh CN et al. PLoS One. 2013;8(1):e Aichelburg MC et al. Clin Infect Dis Apr 1;48(7): Raby E et al. PLoS One Jun 18;3(6):e2489. Hsia EC et al. Arthritis Rheum Jul;64(7): Ponce De Leon D et al. J Rheumatol May;35(5): Matulis G et al. Ann Rheum Dis Jan;67(1): Jason Andrews et al, Lancet Respir Med Apr;5(4): Mandalakas A et al, AJRCCM, Vol 191: Garazzino S et al. Pediatr Infect Dis J Sep;33(9):e Howley MM et al. Pediatr Infect Dis J Aug 4. Sollai et al. BMC Infectious Diseases 2014, 14 (Suppl 1):S6 LaCourse SM et al. J Acquir Immune Defic Syndr Jan 30. doi: Mathad JS et al. AJRCCM online.published on 14-January-2016, /rccm OC Mathad JS et al. PLoS One Mar 21;9(3):e Lighter-Fisher J, Surette AM. Obstet Gynecol Jun;119(6): Matsumoto K et al, Kekkaku Vol 91, No.2:45-48, 2016 Li CY et al, Journal of Microbiology, Immunology and Infection (2015) 48, 263e268 Zellweger et al, Loddenkemper et al., AJRCCM, 12 March 2015 Diel R et al. Am J Respir Crit Care Med Jan 1;183(1): Arend SM et al. Am J Respir Crit Care Med Mar 15;175(6): Gao L et al, Lancet Infect Dis Jul 14. pii: S (17) doi: /S (17) Jason Andrews et al, Lancet Respir Med Apr;5(4): Altet N et al, Ann Am Thorac Soc 2015 May;12(5):680-8 Soborg C et al. Eur Respir J Aug;44(2): Diel R et al. Chest Jul;142(1): Rogerson TE et al. Am J Kidney Dis Jan;61(1): What we know from >decade of IGRA use:. IGRAs = Replacing most TST use in TB programs in the US, many countries of W. Europe, Japan, Taiwan, Singapore, and Korea IGRAs are superior to TST in BCG vaccinated populations in both children and adults (sensitivity, specificity and PPV) QFT performs consistently in high risk populations and correlate better to risk than the TST IGRAs = cost effective compared to TST eliminate unnecessary radiation exposure, medical exams, and medical error from unnecessary treatment IGRA operational advantages = convenience for patients and higher quality care 3

4 There is no gold standard for LTBI (no direct evidence) LEVELS OF PROOF for test accuracy Efficacy of preventive therapy Stronger Predictive value for active TB Correlation to exposure gradient Sensitivity/spec for active TB Concordance with TST Weakest 7 Key study: Incidence of active tuberculosis in individuals with latent tuberculosis infection in rural China (Gao et al, Lancet ID 2017) 2 year follow up study on multi-center cohort: QFT+ or TST+ ( 10mm) 2013: Baseline LTBI prevalence (n=21,022) QFT 18% (13-20%) TST 28% (15-42%) : tracked disease progression by test positivity n=7505 QFT+ (n=4455) TST+ (n=6404) TST+/QFT- (n=3050) TST-/QFT+ (n=1101) TST+/QFT+ (n=3354) Incidence n Cumulative incidence* (95% CI) 1.68% ( ) 0.97% ( ) 0.30% ( ) 2.0% ( ) 1.58% ( ) Incidence/100 person years* (95% CI) 0.87 ( ) 0.50 ( ) 0.16 ( ) 1.03 ( ) 0.82 ( ) *P=< *P=< key populations in communities in rural China could be targeted for latent infection screening and treatment with an IGRA rather than the TST. Gao L et al, Lancet Infect Dis 2017; 17:

5 4th Generation: QuantiFERON-TB Gold Plus SAME test principle-procedure..same technology of QFT QFT-Plus is an improved version of QFT that is replacing QFT-GIT : Sensitivity of ~94% in registration trials Specificity of >97% Innovative CD8 + T-cell stimulating antigens added Optimized for CD4 + and CD8 + response Improvements in test formulation and manufacturing Flexible blood draw options NEW: One Li-heparin tube draw approved for transfer into QFT-Plus tubes NEW: 2 day time limit for blood collection to incubation if Li-heparin tube stored between 2-8 degrees C QFT-Plus: potential test evolution CD8 Antigens 9 Indeterminate rates when using single tube Lithiumheparin blood draw Studies using single tube collection followed by blood transfer to QFT-tubes and immediate incubation Siegel, JCM 2018 QFT-Plus Study N Indeterminate rate QIAGEN clinical trials Package insert 2018 QFT-Plus Gallagher David, Synlab publication 2015, QFT-GIT 263 Oregon US low risk specificity trial including 51 pts with NTM USA, 322 Japan and 199 from Australia (all no risk for TB) 4615 UK migrant clinics study, multiple sites 1/ % 0/733 Zero 10/ % 10 5

6 New CD8 + antigens: WHY? CD8+ T cells and role in TB immunity: MTB-specific CD8 + T cells secrete IFN- and other soluble factors to (1 3): Suppress MTB growth Kill infected cells Directly lyse intracellular MTB BIOMARKER for intracellular burden TB-specific CD8 + T cells that produce IFN- have been: More frequently detected in those with active TB disease vs. latent infection (4, 5) Associated with recent exposure to TB (6) Detectable in active TB subjects with HIV co-infection and young children (7, 8) Observed to decline when patients are exposed to anti-tuberculosis treatment (9) References: 1. Turner, J. et al. (1996) Immunology 87, Brookes, R.H. et al. (2003) Eur. J. Immunol. 33, Stenger, S. et al. (1998) Science 282, Day, C.L. et al. (2011) J. Immunol. 187, Rozot, V. et al. (2013) Eur. J. Immunol. 43, Nikolova, M. et al. (2013) Diagn. Microbiol. Infect. Dis. 75, Chiacchio, T. et al. (2014) J. Infect Lanicioni, C. et al. (2012) Am. J. Respir. Crit. Care Med. 185, Nyendak M. Et al. (2014) PLoS ONE 8, e Epub. 11 QuantiFERON TB Gold In tube Nil control TB Antigen Mitogen control QuantiFERON TB Gold Plus Nil control TB 1 Antigen TB2 Antigen Mitogen control Cells stimulated none CD4+ T-Cells All none CD4+ T-Cells CD4+ and CD8+ T-Cells All Polypeptide Antigens Long peptides (MHC class II) ESAT-6 CFP-10 TB7.7 Long peptides (MHC class II) ESAT-6 CFP-10 TB7.7 Long peptides (MHC class II) ESAT-6 CFP-10 TB7.7 + Additional short peptides (MHC class I) 2 Antigen tubes: More information: 2 data points instead of 1 Allows the calculation of CD8 response Title, Location, Date 12 6

7 QFT-Plus: Can it differentiate patients in the spectrum of TB? MTB specific CD4 T cells produce interferon gamma at all stages MTB specific CD8 T cells more readily detected as bacterial burden increases Infection eliminated With innate immune response With acquired immune response Latent TB infection Subclinical TB disease Active TB disease TST Negative Positive Positive Positive Usually positive IGRA Negative Positive Positive Positive Usually positive Culture Negative Negative Negative Intermittently positive Sputum smear Negative Negative Negative Usually negative Infectious No No No Sporadically Yes Positive Positive or negative Symptoms None None None Mild or non Mild to severe Preferred treatment None None Preventative therapy Multidrug therapy Multidrug therapy Pai, M. et al. (2016) Tuberculosis Nat. Rev. Dis. Primers doi: /nrdp The CD8 signal of QFT-Plus, if present, can provide an expanded picture of TB immunity 13 Additional analysis of TB Antigen Tube values Package Insert data TB2 Minus TB1 (i.e. CD8/CD4 CD4) TB2 TB1 (Nil subtracted) Surrogate for isolated CD8 response Is this is recent infection? Are they more likely to progress? Does this information help inform clinical practice? n=733 n=588 n=357 Potential for additional valuable information for risk stratification? 14 7

8 Multicenter study of QuantiFERON-TB Gold Plus in patients with active tuberculosis Horne D, Narita M et al, IJTLD, 22(6): , 2018 QFT-GIT Sensitivity 94.3% (vs %) (P=0.16) No statistical difference in sensitivity Agreement was 98.7%, Kappa 0.89 (CI ) QFT-GIT quantitative values higher than QFT-Plus Other findings: TB2 greater than TB1: 99/157 or 63% TB1 greater than TB2: 39/157 or 25% TB1 and TB2 equal: 16/157 or 10.2% Median difference between TB2 and TB1 (nil subtracted): 0.14 IU/ml PowerPoint Style Guide 15 WARNING: Lack of a CD8 response does not rule out TB disease or subclinical TB or TB that will progress However, the presence and strength of the CD8 response may help determine risk of progression or disease in the context of the patient scenario Note: There is no currently validated quantitative cut point or threshold for a significant CD8 response 16 8

9 Independent evidence: Sensitivity-Specificity 17 Sensitivity of QFT-Plus Published data (culture confirmed TB) Publication Indeterminate Sensitivity BARCELLINI et al, ERJ % (3/116) 87.93% (102/116) Includes 4/4 HIV infected HOFFMAN et al, CMI %(0/24) 95.8% (23/24) YI et al, Scientific Reports % (5/162) 91% (147/162) Takasaki, J Infect Chemother % (0/99) 99% (98/99) Horne, IJTLD % 7/164 89% (146/164) Fukushima, Kekkaku % 1/ % (72/77) TOTAL N= % 16/ % (588/642) Sensitivity meta-analyses (culture proven TB) QFT - GIT Sester et al. ERJ % Diel et al. Chest % 18 9

10 Specificity of QFT-Plus published data Publication N Specificity (negative/n) BARCELLINI et al, ERJ % (103/166) YI et al, Scientific Reports % (207/212) Moon et el, JCM Takasaki, J Infect Chemother US HCW no risk identified Siegel et al, IJTLD, (includes 51 with pulmonary NTM) 97.1% (607/625) % (104/106) 98.1% (257/262) TOTAL % (1021/1049) 19 Specificity of QFT-Plus Independent data Conservative positive definition in persons with no risk: concordant positive of bothtb1 and TB2 Publication N Specificity (negative/n) BARCELLINI et al, ERJ % (105/106) Moon et el, JCM US HCW no risk 99% (619/625). identified Takasaki, J Infect Chemother % (105/106) 2017 TOTAL % 829/ QuantiFERON-TB Gold Plus (QFT-Plus) ELISA Package Insert. Rev. 02. February

11 QFT-Plus: Clinical performance Specificity Studies FDA approved US Package Insert Overall No loss of specificity with QFT-Plus Total of 733 low-risk subjects Site N QFT QFT-Plus QFT-Plus (concordant positive) % Specificity (95% CI) Australia % ( ) Japan % ( ) Japan % ( ) USA % ( ) Overall % ( ) % Specificity (95% CI) 95.5% ( ) 97.7 % ( ) 98.1 % ( ) 98.1 % ( ) 97.3 % ( ) % Specificity (95% CI) 97.9 % ( ) 99.1 % ( ) % ( ) 99.1 % ( ) 98.9 % ( ) 21 Evidence: CD8 antigens in action 22 11

12 QuantiFERON-TB Gold Plus: Gaining attention in 2016 WHO TB report CD8 and CD4 T-cell response Current IGRA assays primarily detect a CD4 T-cell response. However, a new generation assay, the QuantiFERON-TB Plus (QFT- Plus, Qiagen, Hilden, Germany), has been developed to stimulate gamma interferon production by both CD4 and CD8 T-cells. First results indicate that the CD8 T-cell response may be able to identify people at greater risk of progression to active TB. QuantiFERON-TB Gold Plus: Potential to better identify risk for progression Barcellini L, Borroni E, Brown J, Brunetti E, Campisi D, Castellotti PF et al. First evaluation of QuantiFERON-TB Gold Plus performance in contact screening. Eur Respir J. 2016:ERJ First evaluation of QuantiFERON-TB Gold Plus performance in contact screening TB2:TB1 differential as a surrogate measure for CD8 stimulation 15% of contacts had TB2-TB1 values >0.6 IU/mL (25% of those QFT+) Significantly associated with proximity to the index case p = Significantly associated with European origin p = Overall stronger risk association compared to QFT-GIT QFT-Plus in contact screening has improved performance compared to QFT-GIT... [QFT-Plus performance] suggests a role for the differential value between the two tubes as a proxy for recent infection. Barcellini et al, Eur Respir J Jul 7. pii: ERJ doi: / Epub ahead of print] 24 12

13 NEW! A multicentre verification study of the QFT-Plus ED Pieterman et al, Tuberculosis 108 (2018) Study objective: comparison QFT-Plus vs QFT-GIT in testing at-risk groups N= laboratories in Netherlands and Belgium Reason for screening N Positive by QFT- Plus TB suspicion /263 15% Contact /127 42% investigation Screening before /337 5% immunotherapy Occ health periodic 189 9/189 5% check* Other 57 13/57 23% Unknown 58 12/58 21% Percent with CD8 signal >0.6 IU/ml TB2-TB1 17% 33% 11% 33% 15% 33% The most striking observation of this study was that one third of all positive tested contact screening subjects had a true difference in *HCWs working with TB patients or possibly Mtb infected materials IFN γ release between TB1 and TB2 PowerPoint Style Guide 25 Evidence: QFT-Plus adding value in immunocompromised persons 26 13

14 1st evaluation of QFT-Plus performance in PLHIV (high-burden setting) Telisinghe et al. (2016) The sensitivity of the QuantiFERON -TB Gold Plus assay in Zambian adults with active tuberculosis. Int. J. Tuberc. Lung Dis. 21(6) Study design: Prospective recruitment of Zambian patients with pulmonarytb Mean age of 32, 73% male; 63% HIV infected, BMI <18.5 (>50%) 108 consecutive smear or Xpert + QFT-Plus results 108 Pulmonary TB patients 68 HIV-positive 39 smear+, 29 Xpert+ 40 HIV-negative 34 smear+, 6 Xpert+ 58 Positive 6 Negative 4 Indeterminate 32 Positive 5 Negative 3 Indeterminate 85% 6% 80% 8% QFT-Plus performance in PLHIV (high-burden setting) cont. QFT-Plus results not affected by HIV status Median IFN γ was higher in TB2 than in TB1 irrespective of HIV status HIV negative: 20% of negative/indeterminate results on TB1 were positive on TB2 HIV positive: 29% of negative/indeterminate results on TB1 were positive on TB2. QFT Plus negative/indeterminate (n=18) were associated with nutritional status (76% underweight) and not associated with HIV status Compared to prior study in their institution with similar cohorts (Raby 2007) QFT not affected by HIV status and less affected by low CD4 count (results in % below) Telisinghe et al, INT J TUBERC LUNG DIS 21(6):

15 3-way comparison: QFT-Plus, QFT-GIT and T-Spot in active TB K. Fukushima et al, Kekkaku, Vol. 93, No. 10: , 2018 N= 77 culture or LAMP/PCR proven pulmonary TB patients Average 80 years old T-SPOT cut point =8 spots (blood age >8hrs with additive T-cell Xtend) Assay Sensitivity (%) Indeterminate or invalid (%) QFT-Plus** 72/77 (93.5) 1 (1.3) QFT-GIT 70/77 (90.9) 3 (3.9) T-SPOT 57/77 (74.0)* 6 (7.8) **2 of the 3 QFT-GIT indeterminates were positive for QFT-plus due to positive TB2 tube Sensitivity by assay N=20 <age 80 N=57 >age80 N=23 CD4<200 QFT-Plus (%) QFT-GIT (%) * T-Spot (%) * *statistically significant p<0.05 from both QFTs QFT-plus had the highest sensitivity in all age groups and was significantly higher than Elispot in active TB, elderly patients (p<0.005) and those with low CD4 29 NEW! ELISA-IGRA study in the elderly Quantiferon-TB Gold Plus is a More Sensitive Screening Tool than Quantiferon-TB Gold In-Tube for Latent Tuberculosis Infection among Older Adults in Long-Term Care Facility Jung Yien Chien et al, J. Clin. Microbiol. doi: /jcm , Posted Online 23 May 2018 Study Design: QFT-GIT/QFT-Plus comparison study LTBI sensitivity, specificity, PPV and NPV derived from reproducible positive results N=229 51% male Median age 80 yrs ( yrs) Positive results Sensitivity Specificity PPV NPV QFT-GIT 28.8% 89.4% 95.7% 89.4% 95.7% QFT-Plus 32.3% 100%* 95.1% 89.2% 100%* Key findings: *P<0.05 QFT Plus had significantly higher LTBI sensitivity and NPV and equal specificity and PPV compared to QFT GIT QFT GIT had decreased in sensitivity over age 75, whereas no loss in sensitivity was seen with QFT Plus Positive TB2 test results significantly increased the sensitivity of QFT Plus, from 86.4% to 100.0% (P=0.004) 30 15

16 Japanese IGRA Comparison LTBI trial among patients with rheumatoid arthritis Igari H, Ishikawa S, Nakazawa T, Oya Y, Futami H, Tsuyuzaki M, Suzuki K, Matsumura R Infect Chemother Feb;24(2): doi: /j.jiac N=154 Average age 66.5 years Compared results by assay type and CD4 and CD8 response 63% on steroids, 53% on biologic agents, 76% on methotrexate Assay type Positive (%) Negative (%) Indeterminate (%) QFT-Plus 15 (9.7) 138 (89.6) 1 (0.7) * TSpot-TB 7 (4.5) 143 (92.9) 4 (2.6) *P>0.05 Estimated Japanese LTBI prevalence for age yrs (2015, Matsumoto): 10.6% -15% QFT-Plus positive rate significantly higher than TSPOT but lower than expected age group prevalence Higher QFT-Plus + rate was not driven by CD8 tube (TB2) suggests these patients are not newly infected or in the process of developing active TB Positive rates impacted by CD4 and CD8 count of both assays (Indication: careful interpretation of negative results ) 31 Period 1 Period 2 One-Year Experience with QuantiFERON-TB Gold Plus in Patients with Immunosuppressive Conditions (Spain) A. Fernandez-Blazquez et al, Am J Respir Crit Care Med 2018;197:A5549, Study Design: Assessment of QFT-Plus by comparing results from 2 periods of head to head testing of patients with QFT-GIT and T-Spot.TB (5/15 to 6/16) vs QFT-Plus and TSTB (7/16 to 7/17) Risk factors: HIV, hematologic diseases, inflammatory bowel disease, rheumatic disease, candidates for biological therapy % Positive % Indeterminate Agreement Kappa QFT-GIT 14.33% %, 0.53 TSTB N=1535 p< % 8.47 p< QFT-Plus %* 0.61* N=1464 p< TSTB FINDINGS Significantly higher agreement between QFT-Plus and TSTB Significantly lower indeterminate rates by both QFTs compared to TSTB Authors conclusion: The performance of QTF-Plus improves that of QTF-GIT, achieving substantial strength of agreement with TSTB. Poster ATS

17 QuantiFERON TB Gold Plus in renal transplantation receiving immune suppressive agents (Japan) H Igari et al, Am J Respir Crit Care Med 2018;197:A5548, Study Design: 113 renal transplantation patients tested with QFT-Plus. Percentage of CD4 T- cell or CD8 T-cell was determined by flow cytometry N=113 Mean age 49 yrs (44-63) % Positive % Indeterminate QFT-Plus TB2 4.4 TB1 5.3 FINDINGS Patients with CD8 T-cell >=600/μL and CD4/CD8 ratio <1.0 had significantly higher positive rates. CD8 T-cell counts showed a positive correlation with IFN-gamma production in TB-1 and TB-2, however, CD4 counts did not. QFT-Plus had significantly lower indeterminate rates compared to elispot Authors conclusion: QFT-Plus positive rate of 5.3% is acceptable in consideration of Japanese TB statistics. Our result demonstrated the CD8 T-cell dominant immune response to TB specific antigen in the patients of renal transplantation Poster ATS Summary QFT-Plus is an improved version of QFT-GIT and moving the field of LTBI forward CD8 responses correspond to new infection in contacts, exposure and TB burden in active TB (Barcellini 2016, Petruccioli 2017, Knierer 2017) Compared to QFT_GIT, QFT-Plus with higher sensitivity in the elderly (Chien 2018, Fukushima-2018 in press) Unlike QFT-GIT, QFT-Plus results are not impacted by HIV status and less impacted by CD4 count (Telisinghe 2017, Walles 2018 pregnancy study, Fukushima 2018) In direct comparison studies in active TB and rheumatoid arthritis patients, QFT-Plus is significantly more sensitive than elispot (2018 Fukushima 2018, Igari 2018) 34 17

18 The future QFT-Plus moving the field of LTBI forward: Research questions CD8 responses as a biomarker of new infection biomarker of incipient TB? Will TB2 and CD8 response have clinical utility? The CD8 signal: Is there a quantitative threshold that is significant? 2 antigen tubes=2 results in one test: 1. What is its utility in maximizing specificity in low risk persons being tested? 2. Will test conversion that signifying new infection be more evident? Will QFT-Plus perform better in young children as it does in the extreme elderly? 35 Using QFT-Plus results: case scenarios Sample to Insight 18

19 Golden Rules: NEVER use a TST or IGRA to: Rule out disease in TB suspects (symptoms, abnormal CXR or physical finding suspicious of TB) Rule out LTBI in immunocompromised individuals in the setting of high exposure and high risk of disease progression (e.g., HIV, children under 5, transplant patients, those on immunosuppressive drugs) NO TEST CAN REPLACE CLINICAL JUDGMENT!!!! TB EXPOSURE SCENARIO: CONTACT INVESTIGATION Scenario 1: In a S. American country, a rheumatologist has 3+ smear positive active cavitary tuberculosis and coughing for 2 months She takes the contact investigation upon herself. Her strain is pansusceptible She has 2 daughters (age 1 and 3), a baby sitter and husband in her home and visits with her sister frequently. QFT-Plus is performed Sample to Insight 38 19

20 TB EXPOSURE SCENARIO: CONTACT INVESTIGATION Scenario 1: In a S. American country, a rheumatologist has active cavitary tuberculosis and coughing for 2 months She has 2 daughters (age 1 and 3), a baby sitter and husband in her home and visits with her sister frequently. QFT-Plus is performed 6/18 Husband: Positive Babysitter: Positive Sister: Positive 2 daughters: Negative Babysitter s 6 yr old child: Negative (occasional contact) CXRs performed on all household contacts: NORMAL Isoniazid started on husband, babysitter, sister and 2 children (All asymptomatic with normal examinations) Is primary prophylaxis of the QFT-negative daughters warranted? YES, consistent with US and WHO guidelines What next? Sample to Insight 39 TB EXPOSURE SCENARIO: CONTACT INVESTIGATION Scenario 1: Examining the QFT results Initial QFT June 2018 and repeated Sept 2018 Daughter age 3 Check list: Control values Consistency of TB1 and TB2 Change in values between tests? Conversion? Weak or strong? Findings: Nil close to zero Healthy mitogen responses Healthy conversion from 0.02 to >2 iu/ml Diagnosis: LTBI, recent conversion Clinical management: Complete 9 months INH 40 20

21 QuantiFERON-TB Gold Plus (QFT-Plus) Interpretation of QFT-Plus results (1) Nil (IU/ml) TB1 minus Nil (IU/ml) and 25% of Nil Any >8.0 Any <0.35 OR 0.35 and <25% of Nil TB2 minus Nil (IU/ml) Mitogen minus Nil (IU/ml) QFT-Plus result Report/ Interpretation Any Any Positive M. tuberculosis infection likely 0.35 and 25% of Nil 0.5 Negative M. tuberculosis infection NOT likely <0.5 Indeterminate Likelihood of M. tuberculosis infection cannot be determined Note: Cutoffs have not changed from QFT: revalidated 0.35 as most clinically relevant. Positive results by TB1, TB2, or both are considered positive. 1. QuantiFERON-TB Gold Plus (QFT-Plus) ELISA Package Insert. Rev. 02. February Systematically assessing both qualitative and quantitative results 1. Review control values to: Assess the quality of the host response Assess potential technical error What to expect in a healthy patient with NO risk of false negative or indeterminate? Nil value close to zero Mitogen value near 10 IU/ml or above 2. Review quantitative values of antigen (TB1 and TB2) to: Assess values in light of control results Assess potential technical error (eg. TB1>>>TB2) What to expect? TB1 and TB2 values should be close in value, or TB2>TB1 21

22 TB EXPOSURE SCENARIO: CONTACT INVESTIGATION Scenario 1: Examining the QFT results Initial QFT June 2018 and repeated Sept 2018 Daughter age 1 Check list: Control values Consistency of TB1 and TB2 Change in values between tests? Findings: Nil closer to zero than 8.0 IU/ml Healthy mitogen responses Missing: 3 of 4 TB1 and TB2 values Documented transmission hence, Important to ensure Diagnosis: LTBI unlikely Clinical management: 1. Obtain all TB1 and TB2 quantitative values 2. If values close to zero, stop INH 3. If values close to cut point consider continuing INH? ---conservative approach in setting with known transmission and highly vulnerable contact 43 TST and IGRA test interpretation: false-negative or indeterminate results Host factors affecting TST and likely IGRAs HIV- low CD4, no ARVs Recent TB infection (<8 weeks) Infections (viral, fungal, bacterial) Other illness affecting lymphoid organs Live virus vaccination Immunosuppressive drugs Overwhelming TB Malnutrition Age (<2 years, elderly) Does our patient have any of these factors? 22

23 TB EXPOSURE SCENARIO: CONTACT INVESTIGATION Scenario 1: Examining the QFT results Initial QFT June 2018 and repeated Sept 2018 Husband Check list: Control values Consistency of TB1 and TB2 Change in values between tests? Findings: Positive, valid but unusual Nil value high but closer to zero than 8 IU/ml (cut point for nil indeterminate) Mitogen response lower than expected TB1 and TB2 values >25% the nil value and perfect duplication of results Diagnosis: LTBI Clinical management: 1. No change in INH treatment 45 Indeterminate QFT results Causes High Nil (> 8 IU/ml) Mitogen Nil < 0.5 IU/ml May indicate: Excessive levels of circulating IFN- (e.g., another infection) Presence of heterophile antibody Incorrect sample handling Very rare Over vigorous shaking at high temperatures Disturbing material on surface of gel when sampling for ELISA In clinical studies*, < 0.25% of subjects had IFN- > 8 IU/ml for Nil May indicate: Incorrect sample handling > 16 hours from blood specimen draw to incubation Transportation / incubation at incorrect temperature Inadequate shaking of tubes- most common cause Overfilling of tubes 23

24 Key points Summary: Highly infectious index case with contacts under age 5, known transmission (QFT conversion of 3 yr old, totaling 4/5+ contacts) Conservative approach: ensure reviewing quantitative as well as qualitative results, especially when the patient is vulnerable to false-negative results. Any immune response may be helpful in making a clinical decision Test conversion was not subtle: both TB1 and TB2 values went from near zero to >1.9 IU/ml indicating true conversion Doctors are not robots: Decision to test is a decision to think! (John Bernardo MD, Boston) Use clinical patient information, risks and a systematic approach to review quantitative results to make final management decisions Seeking help and consultation This doctor has been using QFT-Plus to monitor progress of active TB treatment. He notices fluctuations and wants to know why. What s missing from the data that was sent? Nil and Mitogen control values Clinical information about TB risk, co-morbidities, nutritional status, and clinical response to treatment What s available in the literature? 48 24

25 Effect of tuberculosis treatment on newly developed QuantiFERON- TB Gold Plus Kamada, Arisu et al, National Hospital Organization Hokkaido Medical Center, Sapporo, Japan P1174, 2016 ATS Quantitative results (IU/mL) During Treatment N=38 Significant decreases of interferon gamma responses were observed during treatment of active TB in both TB1 and TB2 tubes in the first 3 months. The delta (TB2-TB1) between tubes was statistically significant in the latter half and throughout treatment (P=<.05). The finding suggests CD8+ responses (represented by the difference between the 2 tubes) declined with TB treatment 49 Seeking help and consultation This doctor has been using QFT-Plus to monitor progress of active TB treatment. He notices fluctuations and wants to know why. Is it appropriate to use QFT-Plus for monitoring treatment? NO! Like the TST, IGRAs should not be used for treatment monitoring until there is more evidence 50 25

26 Summary Although better than TST, IGRAs are not panaceas: Doctors must remain doctors and use their clinical assessment Interpretation and management of IGRA results is optimized when the following is taken into consideration: Quantitative values of controls and antigen tubes Risk of infection and population prevalence of LTBI Risk of disease progression or potential bad outcome if LTBI is missed Risk vs. benefit of treatment The CD8 response may be helpful in assessing where a patient falls in the TB spectrum of infection to disease QFT Plus is moving the field forward in LTBI: providing more information than prior IGRAs with the new CD8 antigens and 2 nd antigen tube New evidence continues to be favorable for QFT Plus, especially in immunocompromised populations 51 THANK YOU FOR YOUR ATTENTION! Title, Location, Date 52 26