Pro-apoptotic Drugs as Host-Directed Treatments for Pulmonary Tuberculosis

During the early phase of infection, Mycobacterium tuberculosis proliferates in macrophages and other
cells, preventing apoptosis by the induction of proteins such as from the Bcl-2 family, leading to necrosis of the
infected cells. Necrosis increases tuberculosis (TB)-associated morbidity by causing tissue destruction,
inducing inflammation, promoting fibrosis, and impairing vascular supply, thereby reducing the penetration of
antimicrobials and immune cells to the areas where they are needed most. We have recently demonstrated
that adjunctive use of navitoclax, an orally bioavailable, pro-apoptotic small molecule Bcl-2 inhibitor (in clinical
trials for cancer treatments), improves bacterial elimination and decreases lung damage in animal models of
TB. Additionally, navitoclax has anti-fibrotic effects, which can reverse and prevent lung fibrosis as well as
promote antibiotic penetration. In fact, post-TB lung damage is a recognized consequence of pulmonary TB,
with associated chronic adverse outcomes beyond the TB treatments, including bronchiectasis, poor lung
function and respiratory symptoms in both adults and children. Our central hypothesis is that navitoclax (or
similar pro-apoptotic drugs) could be used as a cell death mechanism (CDM)-based small molecule, host-
directed therapy (HDT) approach to shorten TB treatments, and prevent post-TB lung damage. To understand
how these novel therapeutics impact the lung immune landscape, remodeling and bacterial clearance, we have
developed several novel, clinically translatable positron emission tomography (PET)-based imaging biomarkers
to longitudinally profile lesional characteristics in live animals: 18F-ICMT-11 for apoptosis, 18F-FAPI-74 for
fibrosis, 11C-rifampin and 18F-pretomanid (both chemically identical to the parent antibiotic) for tissue antibiotic
exposures as well as advanced magnetic resonance and computed tomography imaging to visualize
pulmonary damage and necrosis. Finally, we have developed complementary high-dimensional
immunophenotyping by flow cytometry to assess the lung immune landscape, remodeling and fibrosis. We will
develop CDM-based small molecule HDT approaches for TB treatments, which brings together cutting-edge
technologies and cross-disciplinary expertise in TB pathogenesis (Jain), pulmonary immunology (D'Alessio)
and oncology (Carroll). There are currently no HDTs approved for clinical use for the treatment of pulmonary
TB. Therefore, in this proposal, we will leverage our expertise in animal models of TB, advanced whole-body in
vivo imaging and high-dimensional immunophenotyping to gain mechanistic insights on the role of pro-
apoptotic drugs to shorten treatments for drug-susceptible and multi-drug resistant (MDR) pulmonary TB as
well as to prevent post-TB lung damage. Our goals are to utilize novel pro-apoptotic HDTs to develop short (2-
3 months versus current 4-6 months or longer), and efficacious TB treatment regimens which also prevent /
improve post-TB lung damage, as well as develop novel clinically-translatable imaging approaches to expedite
the development of pro-apoptotic drugs for shortening TB treatments.

Grant Number: 1R56AI179012-01A1
NIH Institute/Center: NIH
Principal Investigator: WILLIAM BISHAI