Biomarkers for Tuberculosis. Robert S. Wallis, MD, FIDSA Senior Director, Pfizer

Transcription

1 Biomarkers for Tuberculosis Robert S. Wallis, MD, FIDSA Senior Director, Pfizer

2 TB Global Burden total cases WHO 2009

3 TB Global Burden case rates WHO 2009

4 HIV prevalence in TB cases WHO 2009

5 TB Trends by Region Dye, Lancet 2006

6 Diagnostics Tuberculin Skin test TB-specific Interferon release Sputum culture smear agar liquid media

7 Prognostics Biomarkers HIV TNF blockers, corticosteroids Diabetes Smoking, air pollution Genetic factors BCG Isoniazid TB treatment

8 Biomarker Definitions: Endpoints Clinical endpoint A characteristic or variable indicating how a patient feels, functions, or survives. Biomarker (biological marker) A measurable characteristic that is an indicator of normal biological processes, pathogenic processes, or pharmacological responses to a therapeutic intervention. Surrogate endpoint A biomarker that is intended to substitute for a clinical endpoint based on epidemiological, therapeutic, pathophysiologic, or other scientific evidence.

9 TB Biomarker Needs In newly diagnosed active TB cases: predictors of durable (non-relapsing) cure In persons with latent TB infection: indicators of reactivation risk and effectiveness of latent TB treatment In all except active TB cases: predictors of vaccine-induced protection Special populations: children and HIV-infected

10 Validation vs. Qualification Validation: Assay performance Qualification: Relationship between marker and outcome 1. Biologic plausibility 2. Prognosis of clinical outcomes in disease 3. Capturing therapeutic effect in clinical trials

11 Predicting durable TB cure Microbial markers in sputum 2-month culture conversion Other microbial markers Mycobactericidal activity TB-specific T cell function Macrophage activation markers Multiple host markers Serial colony counts or time to culture positivity Other microbial markers Urine M. tuberculosis DNA Volatile organic compounds Whole blood culture IFNγ/ IL-4 δ2 splice variant Neopterin, procalcitonin, C-reactive protein, soluble intercellular adhesion molecule 1, soluble urokinase plasminogen activator receptor, monocyte CDllc Proteomics Transcriptomics

12 2-month culture conversion

13 2-month culture conversion

14 Meta-regression analysis P<

15 2-mo status shortcomings Poor performance in individual patients Sensitivity: 50% PPV: 18% Within subject variability likely hidden by convention of obtaining cultures once monthly Specific bacterial subpopulations causing relapse may also not be well represented in sputum

16 Other sputum markers Serial CFU counts or time-to-positive in MGIT Lipoarabinomannan Antigen 85 85B RNA Isocitrate lyase RNA Prognostic significance uncertain Sputum markers have limited or no role in pediatric TB

17 TB Transrenal (tr)dna bp fragments of IS6110 TB DNA DNA fragments arise due to apoptosis of host cells, studied originally for molecular prenatal diagnosis (Xenomics) Highly sensitive nested PCR amplification Detected in urine of 34/43 TB patients but not in healthy controls No patients had overt renal TB All of 20 patients who initially were positive cleared after 2 months of therapy If validated, may be particularly useful in pediatric TB Cannas, IJTLD 2008

18 Other non-sputum microbial markers Urinary LAM, proteins Serum antigen 85 Volatile organic compounds in exhaled breath May be of host or microbial origin All only at stage of biologic plausibility

19 Whole blood bactericidal activity (WBA) PNU WBA ( log CFU) mg 300 mg 600 mg 1000 mg 1500 mg hours Kumar, ICAAC 2009

20 WBA vs. drug concentration WBA ( log CFU) fold MIC (parent+metabolite) Kumar, ICAAC 2009

21 Serum markers of macrophage activation Marker Pre-Rx Post-Rx P Neopterin nm/l 21.0 ± ± CRP mg/l 47.7± ± SAA mg/l 140 ±89 11 ± β2m mg/l 2.9 ± ± Post-Rx neopterin Well TB relapse Other illness Alive Dead Alive Dead Alive numbers of subjects high (>8.7 nm/l) nrml(<8.7 nm/l) HIV negative only Hosp, Lung 1997

22 Gene Expression Profiles Antimicrobial Inflammation Chemokines Vesicle trafficking Healthy contacts TB patients Jacobsen, J Mol Med 2007

23 Gene expression profiles Mistry, JID 2007 A R C L

24 Agranoff, Lancet 2006

25 Gene expression profiles and TB status

26 Indicators of reactivation risk TB-specific T cell function Macrophage activation ESAT-6/CFP-10 induced IFNγ IFN-induced protein 10 IFNγ/IL-4 δ2 splice variant Neopterin Procalcitonin

27 ESAT-6/CFP-10 Induced IFNγ and TB risk Diel, AJRCCM 2008

28 ESAT-6/CFP-10 skin test TB-infected guinea pigs 25 skin test diam meter (mm) unvaccinated BCG vaccinated survival (wks) Weldingh, PLoS ONE 2008

29 Predicting vaccine efficacy TB-specific T cell function IFNγ Polyfunctional T cells Mycobactericidal activity Whole blood Mononuclear cells

30 Percutaneous vs. intradermal BCG Intracellular cytokine staining CD4 CD8 Favoring percutaneous

31 Percutaneous vs. intradermal BCG Patient characteristics

32 Percutaneous vs. intradermal BCG TB outcomes Possible N=352 Probable N=213 Definite N=172 <- favoring intradermal favoring percutaneous -> Difference(%)

33 TB Biomarker Strategy

34 Biomarkers for LTBI Household contact study design Index TB case households Control households Blood and urine markers Provide isoniazid treatment of LTBI Identify markers that: Distinguish TB contacts from controls, and That normalize with LTBI treatment