Therapeutic Vaccination and Immune Modulation - New Treatment Strategies for the MDR Tuberculosis Pandemic

Tuberculosis (TB) is a global challenge and for the increasing epidemic of multi-drug resistant (MDR)-TB there is restricted treatment options. This calls for research of new immune-modulating treatment strategies that can strengthen the patients immune system to better fight the TB bacteria. The pro-inflammatory, but still immunosuppressive mediator prostaglandin E2 (PGE2) is produced by cyclooxygenase-2 (COX-2) in inflamed infected tissue. Studies from both human and animal models show that COX-2 inhibitors (COX-2i) can improve the immune system and strengthen vaccines responses.

Hypothesis

1. A hyperactive COX-2/PGE2 signal system in active TB causes down-regulated immune responses that favour TB survival, but this can be abrogated by COX-2i. 2. TB-specific immunisation with targeted antigens presented as a therapeutic TB vaccine and enhanced by COX-2i will improve immune-mediated host clearance of TB. 3. Combinations of COX-2i and a therapeutic TB vaccine to conventional anti-TB chemotherapy offer new treatment modalities for TB, including MDR/XDR-TB.

Approach to test the hypothesis

1. Study design: 4-arm, open and randomized clinical intervention trial of patients starting treatment for active TB in specialized Norwegian TB centres and where two arms will receive the COX-2i etoricoxib with and without a TB vaccine, one arm vaccine only and the last arm serve as control receiving only standard anti-TB therapy. For safety precautions, only patients bearing sensitive TB strains are included and study arms will be sequentially introduced. 2. In a mouse model examine in more detail the effects of reversion of chronic inflammation with COX-2i locally in tissue and the interplay with TB vaccine responses, immune regulation, correlates of protection and survival in a well-characterized model for TB-exposed mice.

The hypothesis is that treating TB patients with a therapeutic TB vaccine and COX-2 inhibiting drugs in addition to standard antibiotic TB therapy will improve the patients immune system and boost TB vaccine responses.

The project will provide safety and immunogenicity data from a Norwegian phase 1 clinical trial of the therapeutic TB vaccine candidate H56:IC31 and the COX-2i etoricoxib given to TB patients together with standard TB antibiotics.

The investigators will also perform exploratory in-depth studies of immune regulatory mechanisms and try to identify biomarkers for efficacy of treatment both in humans and in a parallel mouse model. These results may further optimize the therapeutic strategy and prepare for larger clinical trials and finally contribute to new treatment options for MDR-TB.

Objectives:

* Study the safety and tolerability of etoricoxib given for 20 weeks (day 0-140) alone and in combination with the therapeutic TB vaccine H56:IC31 given as two immunizations at day 84 and day 140 in patients with active TB disease treated with conventional 26-week anti-TB chemotherapy. * Study the immune effects of etoricoxib given for 20 weeks (day 0-140) on immune regulation and TB vaccine (H56:IC31) immunogenicity in patients with active TB disease treated with conventional 26-week anti-TB chemotherapy.