Diagnosis of Latent TB Infection

Diagnosis of Latent TB Infection Patricio Escalante, MD, MSc, FCCP Division of Pulmonary and Critical Care Medicine Mycobacterial and Bronchiectasis Clinic Olmsted County Tuberculosis Clinic Mayo Clinic 2014 MFMER slide-1

Disclosures Patent applications for technology related to latent TB infection immunodiagnostics No relevant financial relationships One off-label/investigative use of a commercial product/device: QFT-TB Plus 2014 MFMER slide-2

Learning Objectives Explain Use of TST Explain Use of IGRA Testing 2014 MFMER slide-3

Case 24 yo US-born male referred for possible LTBI and h/o IBD Asymptomatic, no F/C/NS/WL. Normal BMs PMHx: Crohn s disease x ~ 3 years with 2 flare-ups (diarrhea, bloody stools) on 6-MP and prednisone only for flare-ups Primary sclerosing cholangitis (PSC) on liver biopsy Prior h/o TST= 11 mm and (-)CXR: No LTBI treatment; Social Hx: Denies prior TB exposures, traveled to Germany and finished college degree More recent TST= 9 mm, but fluctuating LFTs due to PSC (Anticipated problematic LTBI treatment as per outside MD) 2014 MFMER slide-4

Case PMHx Afebrile, no LAD, lungs CTA, otherwise unrevealing Labs: Normal CBC MRI normal liver and bile ducts QFT: (11/17/10): (-) results QFT (2/7/2012): Nil = 0.02 Ag-Nil = 0.01 (-) results Mitogen-Nil = 15.17 TSPOT-TB: Nil = 0; Panel A = 0; Panel B = 0; Pos control = >20: (-) results 2014 MFMER slide-5

Diagnosis? (+)/(-)TST & (-)/(-)IGRA LTBI?? 2014 MFMER slide-6

Small PM, Fujiwara PI. NEJM 2001 2014 MFMER slide-7

Spectrum of TB infection Lin PL, Flynn JL. J Immunol 2010 2014 MFMER slide-8

Mack U et al. Eur Resp J 2010 2014 MFMER slide-9

Latent TB Infection Diagnostics 2014 MFMER slide-10

TST and IGRAs Lalvani A. et al. Chest 2007 2014 MFMER slide-11

IGRAs: ESAT-6 and CFP-10 (RD1-Antigens) Tuberculosis complex ESAT Antigens CFP M tuberculosis + + M africanum + + M bovis + + BCG substrain gothenburg - - moreau - - tice - - tokyo - - danish - - glaxo - - montreal - - pasteur - - Environmental strains ESAT Antigens CFP M abcessus - - M avium - - M branderi - - M celatum - - M chelonae - - M fortuitum - - M gordonii - - M intracellulare - - M kansasii + + M malmoense - - M marinum + + M oenavense - - M scrofulaceum - - M smegmatis - - M szulgai + + M terrae - - M vaccae - - M xenopi - - 2014 MFMER slide-12

TST vs. IGRAs: Specificity # Studies Specificity (95% CI) Chi-Square for heterogeneity (p value) TST 8 0.66 (0.46-0.86) 0.001 Not BCG vaccinated 3 0.98 (0.96-1.00) NS BCG Vaccinated 5 0.56 (0.34-0.78) 0.001 10 mm 6 0.58 (0.37-0.79) 0.001 15 mm 3 0.87 (0.70-1.00) 0.001 QuantiFERON-TB Gold 9 0.97 (0.95-0.99) 0.01 Not BCG vaccinated 2 1.0 (0.94-1.0) NS BCG Vaccinated 7 0.96 (0.94-0.99) 0.01 Elispot or T-SPOT.TB 4 0.92 (0.88-0.95) 0.01 Menzies D, et al. Ann Intern Med 2007 2014 MFMER slide-13

TST vs. IGRAs: Sensitivity # Studies Sensitivity (95% CI) Chi-Square for heterogeneity (p value) TST 14 0.71 (0.65-0.74) 0.001 Size of reaction 5 mm 9 0.74 (0.66-0.82) 0.001 10 mm 4 0.72 (0.50-0.95) 0.01 15 mm 1 0.40 (0.25-0.56) - QuantiFERON-TB Gold 13 0.76 (0.70-0.83) 0.001 Elispot or T-SPOT.TB 12 0.88 (0.81-0.95) 0.001 Menzies D, et al. Ann Intern Med 2007 2014 MFMER slide-14

IGRAs Advantages over TST IGRAs are more specific than TST in BCG vaccinated patients IGRAs correlate well with TST to detect LTBI in contact investigations IGRAs do not require a second visit Mitogen-negative indeterminate results can detect anergic cases IGRAs do not trigger an amnesic response (i.e., boosting effect) Ferrara G, et al. Lancet 2006 Brock I, et al. AJRCCM 2004 Ewer K, et al. Lancet 2003 2014 MFMER slide-15

IGRA limitations IGRAs cannot differentiate LTBI vs. active TB Differences in blood T-cell cytokine and functional signatures between LTBI and active TB 1,2 TST+/IGRA- results in LTBI are probably not always related to false+ TST results Discordant TST+/IGRA- cases can show T-cell activation to RD1- antigens using assays with longer stimulation times 3,4 Moderate concordance (κ= 0.69) between 2 IGRAs 5 IGRA results variability over time 6 Low positive predictive value for TB reactivation 7 (1) Berry MP, Nature 2010; (2) Sutherland JS et al. Eur J Immunol 2009 (3) Pollock NR, et al Infect Control Hosp Epidemiol 2008 (4) Butera O, at el. BMC Infect Dis 2009; (5) Ferrara G, et al. Lancet 2006 (6) van Zyl-Smith RN, Am J Respir Crit Care Med 2009 (7) Pai M et al. CMR 2014 2014 MFMER slide-16

IGRA s Variability Van Zyl-Smit RN, et al. AJRCCM 2009 2014 MFMER slide-17

IGRA s Variability 7/26 (27%) Spontaneous conversions/reversions Van Zyl-Smit RN, et al. AJRCCM 2009 2014 MFMER slide-18

TST effect on IGRA results After TST: 8/26 (30%) boosted IGRA values By 7 th day, (but not by 3 rd day): 2/26 (12.5%) converted IGRA test from (-) to (+) Borderline zone: QTF-IT: 0.2-0.7 IU/ml TSPOT.TB: 4-8 spots Conversion threshold? from 0.35 to > 0.7 IU/ml from < 6 to > 9 spots Van Zyl-Smit RN, et al. AJRCCM 2009 2014 MFMER slide-19

Sources of Variability for IGRAs Manufacturing source (between-lot variability) Pre-analytical sources (+) Time of blood draw (PM), shaking of tubes, short time to incubation (<6hr) (+) Delay in incubation, blood volume, transportation temperature Laboratory analytical sources Imprecision within-run, between-run, between-operator, and between-laboratory More relevant when results are close the assay cutoff Immunological sources Boosting by PPD After TST, 8/26 (30%) boosted IGRA values By 7 th day, (but not by 3 rd day) 2/26 (12.5%) converted IGRA test from (-) to (+) Modulating by pathogen-associated molecular pattern (PAMP) Co-stimulatory signals Pai M, et al. Clin Microbiol Rev 2014 Van Zyl-Smit RN, et al. AJRCCM 2009 2014 MFMER slide-20

IGRAs in HCWs Prospective study in the US (N=2,418) Overall QFT and TSPOT: Conversion: QFT= 6.1% TSPOT= 8.3% TST= 0.9% Reversions: QFT= 76.4% TSPOT= 77.1% With the use of a borderline zone (0.2-0.7): Conversion rate: 2.3% Conversion rate with 2 subsequent (+)IGRAs: QFT= 1.1% TSPOT= 1.3% Unclear risk of TB by using this approach Dorman, SE, et al. Am J Respir Crit Care Med 2014 2014 MFMER slide-21

IGRAs in HIV In active TB and HIV(+), in low-middle income countries Sensitivity: QFT= 61% (95%CI, 47 to 75%) TSPOT= 72% (95%CI, 62 to 81%) Neither IGRA was consistently more sensitive than TST Indeterminate results QFT= 8.2% TSPOT= 5.9% with CD4 < 200 (11.6 vs. 11.4%) Lower with CD4 > 200 (3.1% vs. 7.9%) In suspected LTBI and HIV(+), IGRAs perform similarly to TST Both TST and IGRAs have suboptimal sensitivity, suggesting potential role for using both tests, especially in severely immunosuppressed individuals Cattamanchi A. et al. J Acquir Immune Defic Syndr. 2011 Santin M. et al. PLoS One 2012 Chen J. et al. PLoS One 2011 Pai M, et al. Clin Microbiol Rev 2014 2014 MFMER slide-22

IGRAs in Patients with Immune-Mediated Inflammatory Diseases Risk of TB in patients on Immunosuppressive agents Systematic Review in LTBI Small studies and high variability in immunosuppressive drugs Neither IGRA was consistently more sensitive than TST Risk factors for TB are predictive of IGRA(+) and TST(+) results Immunosuppressive therapy significantly reduce QFT and TST positivity OR for QFT = 0.37 (95%CI, 0.16 to 0.87) OR for TST = 0.28 (95%CI, 0.10 to 0.80) Indeterminate results are similar for QFT and TSPOT (~5%) Limited prospective study data Both TST and IGRAs have suboptimal sensitivity in pts on immunosuppressive drugs, suggesting potential role for using both tests Winthrop KL et al. Ann Rheum 2012 Smith R et al. Curr Opin Rheumatol 2011 Bartalesi F et al. Eur Respir J 2009 Shahidi N et al. Inflamm Bowel Dis 2012 Chang B et al. Clin Rheumatol 2011 Pai M, et al. Clin Microbiol Rev 2014 2014 MFMER slide-23

IGRAs in non-hiv immunosuppression (IBD) Arias-Guillen M et al. Inflamm Bowel Dis 2014 2014 MFMER slide-24

Predictive Value of IGRA and TST Study Population Technique Time PV for TB Diel et al. 2008 (Germany) HHC (N=601) No LTBI Tx (41 vs 219) QTF-GIT vs. TST ~2 yrs IGRA= 14.6% (6/41)* TST 5 = 2.3% (5/219) TST 10 = 5.6% (5/90) Kik et al. 2009 (Netherlands) Immig. HHC (N=339) TST 5 or TST+ QTF-GIT vs. TSPOT vs. TST ~2 yrs QTF= 2.8% (5/178) TSPOT= 3.3%(6/181) TST 10 = 3.1% (9/288) Leung et al. 2010 (Hong Kong) Silicosis Pts (N=308) TSPOT vs. TST ~4 yrs TSPOT+= 7.4% (15/204) TSPOT-= 1.9% (2/104) RR= 4.5* TST 10 = 6.4% (13/203) TST <10 = 3.9% (4/205) Hill et al. 2008 (Gambia) HHC (N=2348) ELISPOT vs. TST 2 yrs TST+= 14/843 (1.7%) ELISPOT+= 11/649 (1.7%) TST+& ELISPOT+= 7/428 (1.6%) TST+ or ELISPOT+= 15/835 (1.8%) TST- & ELISPOT- = 6/813 (0.7%) (*) P< 0.05 2014 MFMER slide-25

Short-term Longitudinal IGRA Studies Pai M, et al. Clin Microbiol Rev 2014 2014 MFMER slide-29

US-CDC Guidelines High rate of false(+) IGRA if prevalence of TB infection <1% IGRA preferred, but TST is acceptable: Low likelihood to return for TST reading (e.g. homeless, drug abusers) Prior BCG vaccination (improve acceptance of LTBI Tx) TST preferred, but IGRA is acceptable: Children < 5 yo Either TST or IGRA may be used without preference Recent TB contacts with active case (Repeat testing 8-10 wks after end of exposure if negative test) Periodic screening of HCW (?) Both TST and IGRA can be considered: High risk of TB infection and progression, and risk of poor outcome HIV (and severe immunosuppression) Children < 5 yo Investigation of active TB (?) To enhance compliance to LTBI Tx (?) Mazurek GH et al. MMWR 2010 2014 MFMER slide-30

QuantiFERON-TB Plus New QFT test version 4 th tube (TB2) to detection of CD8 T-cells TB7.7 antigen was removed from 3 rd tube (TB1) Either or both TB1 and TB2 0.35 IU/mL above nil QFT-Plus vs. QFT-IT in close TB contacts with TST+ (N=119) High agreement (κ = 0.80), but QFT-Plus had stronger association with surrogate measures of TB exposure Contact time >12 h/day: OR= 6.9 vs. 4.6 TB1-TB2 results >0.6 IU/mL: likelihood for contacts to be sleeping in the same room (OR= 4.3) and European origin (OR= 3.2) recent exposure to TB?- QFT-Plus vs. QFT-IT in TB(N=162) vs. low-risk for TB (N=212) IFN-ϒ concentrations of QFT-Plus were lower in TB patients Both QFT-Plus and QFT-IT had high diagnostic accuracy (AUC=0.99), but QFT-Plus had lower sensitivity (91.1%) with the 0.35 IU/mL cut-off. Sensitivity to 96.2% with a cut-off of 0.168 Characterization of CD4 & CD8 T-cell responses (27 TB vs 30 LTBI) TB1 mainly elicited CD4 T-cell responses TB2 induced both CD4 and CD8 responses TB2-specific CD8 responses more often seen in active TB vs. LTBI (44% vs. 20%) Barcellini L, et al. Eur Respir J 2016 Yi L, et al. Sci Rep 2016 Petruccioli E, et al. J of Infect 2016 2014 MFMER slide-31

Proposed Assessment with Combined IGRA and TST for suspected LTBI Careful assessment of risk factors for TB infection and TB progression TST+/ IGRA+ TST+/ IGRA- (*) TST-/ IGRA+ (*) TST-/ IGRA- Repeat IGRA at 3-6 mo? IGRA+ IGRA- LTBI False+ TST due to BCG? IGRA level? Possible LTBI False+ IGRA? or transient infection? No LTBI (**) (*) Either TST+ or IGRA+ can be a significant test in immunosuppression (**) TST-/IGRA- does not rule out LTBI in immunosuppression Adapted from Lalvani A, Pareek M Brit Med Bull 2010 2014 MFMER slide-32

24 yo M (+)/(-)TST, (-)/(-)IGRAs and IBD 02/2012 2014 MFMER slide-33

Take Home Points Despite progress, immunodiagnosis of LTBI remains challenging and areas of controversy exist IGRAs are more specific than TST, but a TST+/IGRA- probably does not always represent a false(-) TST Both TST and IGRAs cannot differentiate between active TB, subclinical TB, LTBI and host-cleared TB infections Serial testing with IGRA is associated with a high rate of conversions and reversions Long-term risk of developing TB with a positive IGRA test is low (low positive predictive value) New diagnostics should not only accurately detect T-cell reactivity against MTB but also improve determination of LTBI with viable MTB at actual risk of TB reactivation 2014 MFMER slide-34

Questions? 2014 MFMER slide-35