Effective tuberculosis (TB) control requires that people who progress from latent
Mycobacterium tuberculosis (MTB) infection (LTBI) to TB disease are identified and treated
before they infect others. A prognostic correlate of risk (COR), based on messenger
ribonucleic acid (mRNA) expression signatures, which prospectively discriminates between TB
cases and healthy controls, has been constructed and validated. Based on published microarray
case-control datasets, the COR has 87% diagnostic sensitivity and 97% specificity for
prevalent TB disease; and in two nested case-control studies, 70% prognostic sensitivity and
84% specificity for incident TB disease occurring within one year of sampling (HIV uninfected
persons). Diagnostic and prognostic performance of the COR has not yet been tested in a
prospective cohort.
COR+ status is not directly associated with LTBI; and may, or may not, be amenable to
preventive therapy. Although effective in the short-term, preventive therapy is not
recommended for treatment of LTBI in HIV uninfected adults living in high TB burden
countries, due to rapid loss of protection; and treatment burden. A 3-month, 12-dose,
once-weekly preventive therapy regimen of high dose Isoniazid (INH) and Rifapentine (3HP) has
been recommended as equivalent to 6 months of daily INH for treatment of LTBI in low TB
burden countries by the World Health Organization (WHO).
A 'screen & treat' strategy, based on serial mass campaigns to provide targeted, short-course
preventive therapy only to COR+ persons at highest risk of TB disease, may offer the solution
for durable, community-wide protection in high TB burden countries. The efficacy of 3HP for
prevention of incident TB disease in COR+ persons has not yet been tested in a clinical
trial.
Primary Aims
1. Test whether preventive therapy (3HP) reduces the rate of incident TB disease, compared
to standard of care (active surveillance), in COR+ persons.
2. Test whether COR status differentiates persons with cumulative prevalent or incident TB
disease from persons without TB disease.
Secondary Aims
1. Estimate whether COR status differentiates persons at high risk for incident TB disease
from persons at low risk for incident TB disease
2. Compare prognostic performance of the COR for incident TB disease with Interferon-gamma
release assay (IGRA).
Phase:
Phase 2/Phase 3
Details
Lead Sponsor:
University of Cape Town
Collaborators:
Aurum Institute Centre for the AIDS Programme of Research in South Africa Fred Hutchinson Cancer Research Center London School of Hygiene and Tropical Medicine South African Tuberculosis Vaccine Initiative University of Stellenbosch