Background. Preclinical evaluation of tuberculosis drugs is generally limited to mice. However, necrosis and hypoxia, key features of human tuberculosis lesions, are lacking in conventional mouse strains. Methods. We used C3HeB/FeJ mice, which develop necrotic lesions in response to Mycobacterium tuberculosis infection. Positron emission tomography in live infected animals, postmortem pimonidazole immunohistochemistry, and bacterial gene expression analyses were used to assess whether tuberculosis lesions in C3HeB/FeJ are hypoxic. Efficacy of combination drug treatment, including PA-824, active against M. tuberculosis under hypoxic conditions, was also evaluated. Results. Tuberculosis lesions in C3HeB/FeJ (but not BALB/c) were found to be hypoxic and associated with up-regulation of known hypoxia-associated bacterial genes (P < .001). Contrary to sustained activity reported elsewhere in BALB/c mice, moxifloxacin and pyrazinamide (MZ) combination was not bactericidal beyond 3 weeks in C3HeB/FeJ. Although PA-824 added significant activity, the novel combination of PA-824 and MZ was less effective than the standard first-line regimen in C3HeB/FeJ. Conclusions. We demonstrate that tuberculosis lesions in C3HeB/FeJ are hypoxic. Activities of some key tuberculosis drug regimens in development are represented differently in C3HeB/FeJ versus BALB/c mice. Because C3HeB/FeJ display key features of human tuberculosis, this strain warrants evaluation as a more pathologically relevant model for preclinical studies.

2-[ ¹⁸ F]-Fluorodeoxysorbitol, a synthetic PET probe, can be used to rapidly, sensitively, and specifically image Gram-negative bacterial infections in animals.

The “Warburg effect” describes a peculiar metabolic feature of many solid tumors, namely their increased glucose uptake and high glycolytic rates, which allow cancer cells to accumulate building blocks for the biosynthesis of macromolecules. During aerobic glycolysis, pyruvate is preferentially metabolized to lactate by the enzyme lactate dehydrogenase-A (LDH-A), suggesting a possible vulnerability at this target for small-molecule inhibition in cancer cells. In this study, we used FX11, a small-molecule inhibitor of LDH-A, to investigate this possible vulnerability in a panel of 15 patient-derived mouse xenograft (PDX) models of pancreatic cancer. Unexpectedly, the p53 status of the PDX tumor determined the response to FX11. Tumors harboring wild-type (WT) TP53 were resistant to FX11. In contrast, tumors harboring mutant TP53 exhibited increased apoptosis, reduced proliferation indices, and attenuated tumor growth when exposed to FX11. [¹⁸F]-FDG PET-CT scans revealed a relative increase in glucose uptake in mutant TP53 versus WT TP53 tumors, with FX11 administration downregulating metabolic activity only in mutant TP53 tumors. Through a noninvasive quantitative assessment of lactate production, as determined by ¹³C magnetic resonance spectroscopy (MRS) of hyperpolarized pyruvate, we confirmed that FX11 administration inhibited pyruvate-to-lactate conversion only in mutant TP53 tumors, a feature associated with reduced expression of the TP53 target gene TIGAR, which is known to regulate glycolysis. Taken together, our findings highlight p53 status in pancreatic cancer as a biomarker to predict sensitivity to LDH-A inhibition, with regard to both real-time noninvasive imaging by ¹³C MRS as well as therapeutic response. Cancer Res; 75(16); 3355–64. ©2015 AACR.

Background. Tuberculosis (TB) leads to the death of 1.7 million people annually. The failure of the bacille Calmette-Guérin vaccine, synergy between

Molecular imaging could fulfill unmet clinical needs for diagnosing and monitoring bacterial infections, if translational barriers are addressed.