Background: According to the World Health Organization (WHO), 10 million people fell ill
with tuberculosis (TB) in 2019, and 1.4 million people died from this disease. Among
infectious agents, Mycobacterium tuberculosis (Mtb) remains the major cause of mortality
and morbidity worldwide. Control of the disease is increasingly complicated due to
growing numbers of infections with multi-drug resistant strains. In Germany, we witnessed
a sharp increase of new cases (7.3 cases per 100,000) in 2015. From 2016 to 2017 the
incidence decreased, while the numbers in 2018 (5,429 reported TB cases; 6.5 cases per
100,000) kept almost unchanged. Migrants from high incidence areas account for the
majority of all TB patients (67,1% in 2019). While pulmonary TB (PTB) is the most common
manifestation, any other organ can be involved. Extrapulmonary TB (EPTB) constitutes for
27,8% (1,321) of all cases in Germany. While the overall incidence of TB is decreasing in
industrialized countries, the proportion of EPTB has been constantly increasing in
Germany and other European countries. The reasons for this are not fully understood. An
extensive retrospective study performed in China showed a significantly higher proportion
of multi-drug resistant TB among patients with EPTB than among patients with PTB. This
clearly highlights the need for improved EPTB control measures in order to avoid the
development of drug resistance and to achieve the goal of TB eradication on a national
and international level (e.g. WHO End-TB-strategy) which is further challenged by the
SARS-CoV-2 pandemic. The mEX-TB project focuses on EPTB with the main goal of optimizing
clinical management of EPTB patients. A prospective clinical cohort of EPTB will be
established, involving multiple researchers and clinical sites (Frankfurt, Heidelberg,
Borstel, Hamburg, Bonn, Cologne), which will enable us to conduct detailed clinical and
translational studies addressing this disease entity.
Description:
Study population, research design and research methods Adult patients newly diagnosed
with EPTB (N=150) will prospectively be enrolled into the study. PTB patients (N=30) will
also be included and serve as a control group to test the technical feasibility. In
addition, a healthy control group (N=30) will be added, mainly to address aim 1. Clinical
data will be collected using standardized questionnaires over the whole treatment period
for each individual.
Additionally, body fluids (blood, urine) will be collected and stored in a central
biobank (Cologne). However, not all contributing centers will be able to provide high
quality peripheral blood mononuclear cells (PBMCs) for storage. In order not to lose
patients with incomplete sample collections, the cohort study will have several strata:
EPTB patients (N=100) with clinical data (e.g. weight gain, imaging results etc.)
and a full collection of bio samples (routine laboratory parameters, peripheral
blood mononuclear cells (PBMCs), PAXgene RNA/DNA tubes for gene signatures, absolute
and relative CD4/CD8 cell count, Vitamin D (25(OH)D), urine, plasma)
EPTB patients (N=50) with clinical data (e.g. weight gain, imaging results,
microbiology results etc.) plus/minus a partial collection of bio samples (e.g.
routine laboratory results, Vitamin D (25(OH)D), PAXgene, plasma)
Healthy controls (N=30) and a full collection of bio samples as described for
stratum 1 at one timepoint.
Data collection Pseudonymized clinical and laboratory data will be recorded at the
following time points: diagnosis/ treatment initiation (day 0 / +/- 7 days); 4 weeks post
treatment initiation (+/- 7 days); 3 months post treatment initiation (+/- 7 days); 6
months post treatment initiation (+/- 7 days); 3 months post end of treatment (+/- 7
days). In patients requiring treatment of more than 6 months (i.e. multi-drug resistant
TB, disseminated TB etc.) data will be collected regularly until end of treatment.
Pseudonymization of patient data and acquisition of biomaterial is performed through a
patient ID-generator. A paper case report form (CRF) will be used to collect patient
data. The CRF data will be then transferred to an electronic database.
Outcome:
Laboratory based biomarkers for assessing treatment responses similar to sputum
conversion used for PTB are not available in most cases of EPTB. Unspecific inflammation
markers such as C-reactive protein (CRP) can be utilized to assess early treatment
response. We will systematically and longitudinally assess radiologic parameters (lesion
size in CT, ultrasonography or MRI), laboratory findings and clinical signs (e.g. weight
gain, less pain, absence of fever etc.). We will then exploit response algorithms
specifically evaluated for EPTB patients initiating anti-TB treatment. A combination of
three clinical parameters will be used 1) improvement in reported symptoms 2) weight gain
(any weight gain or ≥ 5% weight gain) 3) regression of lymph node swelling, pleural or
peritoneal effusion or other local findings, during and after treatment. A combination of
these parameters predicts favorable or unfavorable outcome early during the treatment
process.
Aims:
Our aim is to assess the treatment response using these parameters, supported by two
independent clinicians and experts in the field (blind review). Data will be correlated
with blood based biomarker findings described below. The main objectives of this study
are the development of EPTB specific biomarkers for improved EPTB diagnostics and
assessment of treatment responses by correlating immunological and blood based parameters
and signatures with clinical features at baseline and longitudinally. For this purpose,
our biomarker study will focus on two major aims:
Study aim I: Evaluation of blood biomarkers as diagnostic tools for EPTB Sputum or lung
fluid based laboratory diagnostics as performed with PTB is not possible in most cases of
EPTB. Blood based biomarkers are required.
We will focus on two approaches: 1) blood derived gene expression signatures
associated with tuberculosis; 2) T-cell based assays (e.g. TAM-TB assay).
For this aim, we will first investigate markers that have already been analyzed in
PTB patients. We will also be able to investigate EPTB specific markers in an
unbiased fashion if necessary.
Study aim II: Evaluation of blood biomarkers predicting treatment response or failure and
cure in EPTB
Predicting cure or the risk of treatment failure is crucial for the management of
EPTB. Various outcome definitions for PTB are based on culture and smear results
which is not applicable in EPTB. Our aim is to correlate blood based biomarkers with
the treatment response which we will assess with well-defined clinical parameters.
For this aim we will continue with our evaluation of plasma IP-10 as a simple and
cost-effective treatment response marker. Additional plasma-based markers have been
described in our proposal. More complex markers/signatures (gene expression via
RNA-seq and T-cell response based) will be applied using technical approaches
similar to the ones exploited in Aim 1. We will primarily focus on signatures that
have already been evaluated for PTB. The overarching goal of this unique multicenter
cohort of patients with EPTB is the development.