Six months of drug treatment is standard of care for drug-sensitive pulmonary tuberculosis (TB). Understanding the factors determining the length of treatment required for durable cure would allow individualization of treatment durations. We conducted a prospective, randomized, controlled noninferiority trial (PredictTB) of 4 versus 6 months of chemotherapy in patients with pulmonary TB in South Africa and China. Seven hundred and four participants with newly diagnosed, drug-sensitive TB were enrolled and stratified on the basis of radiographic disease characteristics assessed by FDG PET/CT imaging. Participants with less extensive disease (n = 273) were randomly assigned at week 16 to complete therapy after 4 months or continue receiving treatment for 6 months. This study was stopped early after an interim analysis revealed that patients assigned to the 4-month treatment arm had a higher risk of relapse. Among participants who received 4 months of chemotherapy, 17 of 141 (12.1%) experienced TB-specific unfavorable outcomes compared with only 2 of 132 (1.5%) who completed 6 months of treatment. In the nonrandomized arm that included participants with more extensive disease, only 8 of 248 (3.2%) experienced unfavorable outcomes. Total lung cavity volume and lesion glycolysis at week 16 were associated with the risk of unfavorable outcomes. PET/CT imaging at TB recurrence showed that bacteriological relapses predominantly occurred in active cavities originally present at baseline. Subsequent post hoc automated segmentation of serial PET/CT scans combined with machine learning enabled the classification of participants according to their likelihood of relapse.

BACKGROUND:Non-sputum-based, point-of-care triage tests for pulmonary tuberculosis could enhance tuberculosis diagnostic programs. We assessed the diagnostic accuracy of 2 finger-stick blood tests: the Cepheid 3 gene host-response cartridge (Xpert-HR), which measures 3 host messenger RNA transcripts, and the 3-host protein multibiomarker test (MBT). METHODS:We performed a prospective diagnostic accuracy study of consecutive participants with symptoms compatible with pulmonary tuberculosis in The Gambia, South Africa, Uganda, and Vietnam. A composite reference standard for active pulmonary tuberculosis incorporated chest radiography, symptom resolution, and sputum microbiological test results. A training-test set approach was used to evaluate test cutoff specificities at 90% sensitivity. RESULTS:Between 1 November 2020 and 1 May 2023, we screened 1262 participants aged 12-70 years with cough lasting >2 weeks and another symptom suggestive of tuberculosis. Of those who were classifiable by reference tests, 1154 participants had evaluable Xpert-HR results and 961 had evaluable MBT results. Xpert-HR had an area under the receiver operating characteristic (AUROC) curve of 0.92 at a cutoff of -1.275 or below, with a sensitivity of 92.8%, specificity of 62.5%, positive predictive value of 47.9%, and negative predictive value of 95.9%. The MBT had an AUROC of 0.91 at a cutoff of ≥0.42, with a sensitivity of 91.4%, specificity of 73.2%, positive predictive value of 52.0%, and negative predictive value of 96.4%. CONCLUSIONS:Our results show that both Xpert-HR and the MBT are promising non-sputum-based point-of-care tests. The MBT met the World Health Organization target product profile for a triage test, which suggests it should be further developed.

Bacterial gene expression from sites of infection are poorly studied due to low levels of bacterial mRNA present in clinical samples. Here, we develop Transcript-Capture Seq, which uses customizable biotinylated probes generated in-house to enrich bacteria-specific RNA from host samples before Next Generation Sequencing (NGS). This method results in a >200-fold increase in bacterial mRNA reads from mixed samples and allows analysis of the complete bacterial transcriptome from clinical samples. We apply Transcript-Capture to models of tuberculosis (TB) infection as well as sputum samples from TB patients. TB patients exhibit unexplained heterogeneity in disease progression, and the activity of Mycobacterium tuberculosis (Mtb) has been proposed to affect treatment response. By applying Transcript-Capture to sputum samples collected from TB patients we generate the first complete in vivo bacterial transcriptome of Mtb via NGS. Mtb from patient sputa shows upregulation of genes involved in host lipid utilization and zinc limitation, as well as a similar gene expression profile to Mtb log phase growth in vitro. Applying Transcript-Capture to clinical sputa provides a snapshot of bacterial activity directly from human patients and can be used to investigate the physiological state of bacteria surviving in vivo.

Six months of chemotherapy using current agents is standard of care for pulmonary, drug-sensitive tuberculosis (TB), even though some are believed to be cured more rapidly and others require longer therapy. Understanding what factors determine the length of treatment required for durable cure in individual patients would allow individualization of treatment durations, provide better clinical tools to determine the of appropriate duration of new regimens, as well as reduce the cost of large Phase III studies to determine the optimal combinations to use in TB control programs. We conducted a randomized clinical trial in South Africa and China that recruited 704 participants with newly diagnosed, drug-sensitive pulmonary tuberculosis and stratified them based on radiographic disease characteristics as assessed by FDG PET/CT scan readers. Participants with less extensive disease (N=273) were randomly assigned to complete therapy after four months or continue receiving treatment for six months. Amongst participants who received four months of therapy, 17 of 141 (12.1%) experienced unfavorable outcomes compared to only 2 of 132 (1.5%) who completed six months of treatment (treatment success 98.4% in B, 86.7% in C (difference -11.7%, 95% CI, -18.2%, -5.3%)). In the non-randomized arm that included participants with more extensive disease, only 8 of 248 (3.2%) experienced unfavorable outcomes. Total cavity volume and total lesion glycolysis at week 16 were significantly associated with risk of unfavorable outcome in the randomized participants. Based on PET/CT scans at TB recurrence, bacteriological relapses (confirmed by whole genome sequencing) predominantly occurred in the same active cavities originally present at baseline. Automated segmentation of the serial PET/CT scans was later performed, and machine-learning was used to classify participants according to their likelihood of relapse, allowing the development of predictive models with good performance based on CT, PET, microbiological and clinical characteristics. These results open the possibility for more efficient studies of future TB treatment regimens.

BackgroundTuberculosis (TB) and COVID-19 are the two leading causes of infectious disease mortality worldwide, and their overlap is likely frequent and inevitable. Previous research has shown increased mortality in TB/COVID-coinfected individuals, and emerging evidence suggests that COVID-19 may increase susceptibility to TB. However, the immunological mechanisms underlying these interactions remain unclear. In this study, we aimed to elucidate the impact of prior or concurrent COVID-19 infection on immune profiles of TB patients and those with other respiratory diseases (ORD).MethodsSerum and nasopharyngeal samples were collected from 161 Gambian adolescents and adults with either TB or an ORD. Concurrent COVID-19 infection was determined by PCR, while prior COVID-19 was defined by antibody seropositivity. Multiplex cytokine immunoassays were used to quantify 27 cytokines and chemokines in patient serum samples at baseline, and throughout treatment in TB patients.ResultsStrikingly, TB and ORD patients with prior COVID-19 infection were found to have significantly reduced expression of several cytokines, including IL-1β, TNF-α and IL-7, compared to those without (p<0.035). Moreover, at month-six of anti-TB treatment, seropositive patients had lower serum Basic FGF (p=0.0115), IL-1β (p=0.0326) and IL-8 (p=0.0021) than seronegative. TB patients with acute COVID-19 coinfection had lower levels of IL-8, IL-13, TNF-α and IP-10 than TB-only patients, though these trends did not reach significance (p>0.035).ConclusionsOur findings demonstrate that COVID-19 infection alters the subsequent response to TB and ORDs, potentially contributing to pathogenesis. Further work is necessary to determine whether COVID-19 infection accelerates TB disease progression, though our results experimentally support this hypothesis.

Mycobacterium tuberculosis (M.tb) causes tuberculosis (TB) and remains one of the leading causes of mortality due to an infectious pathogen. Host immune responses have been implicated in driving the progression from infection to severe lung disease. We analyzed longitudinal RNA sequencing (RNAseq) data from the whole blood of 74 TB progressors whose samples were grouped into four six-month intervals preceding diagnosis (the GC6-74 study). We additionally analyzed RNAseq data from an independent cohort of 90 TB patients with positron emission tomography-computed tomography (PET-CT) scan results which were used to categorize them into groups with high and low levels of lung damage (the Catalysis TB Biomarker study). These groups were compared to non-TB controls to obtain a complete whole blood transcriptional profile for individuals spanning from early stages of M.tb infection to TB diagnosis. The results revealed a steady increase in the number of genes that were differentially expressed in progressors at time points closer to diagnosis with 278 genes at 13-18 months, 742 at 7-12 months and 5,131 detected 1-6 months before diagnosis and 9,205 detected in TB patients. A total of 2,144 differentially expressed genes were detected when comparing TB patients with high and low levels of lung damage. There was a large overlap in the genes upregulated in progressors 1-6 months before diagnosis (86%) with those in TB patients. A comprehensive pathway analysis revealed a potent activation of neutrophil and platelet mediated defenses including neutrophil and platelet degranulation, and NET formation at both time points. These pathways were also enriched in TB patients with high levels of lung damage compared to those with low. These findings suggest that neutrophils and platelets play a critical role in TB pathogenesis, and provide details of the timing of specific effector mechanisms that may contribute to TB lung pathology.

Abstract Background The development of a fast and accurate, non-sputum-based point-of-care triage test for tuberculosis (TB) would have a major impact on combating the TB burden worldwide. A new fingerstick blood test has been developed by Cepheid (the Xpert MTB Host Response [MTB-HR] prototype), which generates a “TB score” based on messenger RNA (mRNA) expression of 3 genes. Here we describe the first prospective findings of the MTB-HR prototype. Methods Fingerstick blood from adults presenting with symptoms compatible with TB in South Africa, The Gambia, Uganda, and Vietnam was analyzed using the Cepheid GeneXpert MTB-HR prototype. Accuracy of the Xpert MTB-HR cartridge was determined in relation to GeneXpert Ultra results and a composite microbiological score (GeneXpert Ultra and liquid culture) with patients classified as having TB or other respiratory diseases (ORD). Results When data from all sites (n = 75 TB, 120 ORD) were analyzed, the TB score discriminated between TB and ORD with an area under the curve (AUC) of 0.94 (95% confidence interval [CI], .91–.97), sensitivity of 87% (95% CI, 77–93%) and specificity of 94% (88–97%). When sensitivity was set at 90% for a triage test, specificity was 86% (95% CI, 75–97%). These results were not influenced by human immunodeficiency virus (HIV) status or geographical location. When evaluated against a composite microbiological score (n = 80 TB, 111 ORD), the TB score was able to discriminate between TB and ORD with an AUC of 0.88 (95% CI, .83–.94), 80% sensitivity (95% CI, 76–85%) and 94% specificity (95% CI, 91–96%). Conclusions Our interim data indicate the Cepheid MTB-HR cartridge reaches the minimal target product profile for a point of care triage test for TB using fingerstick blood, regardless of geographic area or HIV infection status.

Pulmonary tuberculosis (PTB) is characterized by lung granulomas, inflammation and tissue destruction. Here we used within-subject peripheral blood gene expression over time to correlate with the within-subject lung metabolic activity, as measured by positron emission tomography (PET) to identify biological processes and pathways underlying overall resolution of lung inflammation. We used next-generation RNA sequencing and [18F]FDG PET-CT data, collected at diagnosis, week 4, and week 24, from 75 successfully cured PTB patients, with the [18F]FDG activity as a surrogate for lung inflammation. Our linear mixed-effects models required that for each individual the slope of the line of [18F]FDG data in the outcome and the slope of the peripheral blood transcript expression data correlate, i.e., the slopes of the outcome and explanatory variables had to be similar. Of 10,295 genes that changed as a function of time, we identified 639 genes whose expression profiles correlated with decreasing [18F]FDG uptake levels in the lungs. Gene enrichment over-representation analysis revealed that numerous biological processes were significantly enriched in the 639 genes, including several well known in TB transcriptomics such as platelet degranulation and response to interferon gamma, thus validating our novel approach. Others not previously associated with TB pathobiology included smooth muscle contraction, a set of pathways related to mitochondrial function and cell death, as well as a set of pathways connecting transcription, translation and vesicle formation. We observed up-regulation in genes associated with B cells, and down-regulation in genes associated with platelet activation. We found 254 transcription factor binding sites to be enriched among the 639 gene promoters. In conclusion, we demonstrated that of the 10,295 gene expression changes in peripheral blood, only a subset of 639 genes correlated with inflammation in the lungs, and the enriched pathways provide a description of the biology of resolution of lung inflammation as detectable in peripheral blood. Surprisingly, resolution of PTB inflammation is positively correlated with smooth muscle contraction and, extending our previous observation on mitochondrial genes, shows the presence of mitochondrial stress. We focused on pathway analysis which can enable therapeutic target discovery and potential modulation of the host response to TB.

Early bactericidal activity studies monitor daily sputum bacterial counts in individuals with tuberculosis (TB) for 14 days during experimental drug treatment. The rate of change in sputum bacterial load over time provides an informative, but imperfect, estimate of drug activity and is considered a critical step in development of new TB drugs. In this clinical study, 160 participants with TB received isoniazid, pyrazinamide, or rifampicin, components of first-line chemotherapy, and moxifloxacin individually and in combination. In addition to standard bacterial enumeration in sputum, participants underwent 2-deoxy-2-[18F]fluoro-d-glucose positron emission tomography and computerized tomography ([18F]FDG-PET/CT) at the beginning and end of the 14-day drug treatment. Quantitating radiological responses to drug treatment provided comparative single and combination drug activity measures across lung lesion types that correlated more closely with established clinical outcomes when combined with sputum enumeration compared to sputum enumeration alone. Rifampicin and rifampicin-containing drug combinations were most effective in reducing both lung lesion volume measured by CT imaging and lesion-associated inflammation measured by PET imaging. Moxifloxacin was not superior to rifampicin in any measure by PET/CT imaging, consistent with its performance in recent phase 3 clinical trials. PET/CT imaging revealed synergy between isoniazid and pyrazinamide and demonstrated that the activity of pyrazinamide was limited to lung lesion, showing the highest FDG uptake during the first 2 weeks of drug treatment. [18F]FDG-PET/CT imaging may be useful for measuring the activity of single drugs and drug combinations during evaluation of potential new TB drug regimens before phase 3 trials.

Improved tuberculosis diagnostics and tools for monitoring treatment response are urgently needed. We developed a robust and simple, PCR-based host-blood transcriptomic signature, RISK6, for multiple applications: identifying individuals at risk of incident disease, as a screening test for subclinical or clinical tuberculosis, and for monitoring tuberculosis treatment. RISK6 utility was validated by blind prediction using quantitative real-time (qRT) PCR in seven independent cohorts. Prognostic performance significantly exceeded that of previous signatures discovered in the same cohort. Performance for diagnosing subclinical and clinical disease in HIV-uninfected and HIV-infected persons, assessed by area under the receiver-operating characteristic curve, exceeded 85%. As a screening test for tuberculosis, the sensitivity at 90% specificity met or approached the benchmarks set out in World Health Organization target product profiles for non-sputum-based tests. RISK6 scores correlated with lung immunopathology activity, measured by positron emission tomography, and tracked treatment response, demonstrating utility as treatment response biomarker, while predicting treatment failure prior to treatment initiation. Performance of the test in capillary blood samples collected by finger-prick was noninferior to venous blood collected in PAXgene tubes. These results support incorporation of RISK6 into rapid, capillary blood-based point-of-care PCR devices for prospective assessment in field studies.

Standard treatment of drug-sensitive pulmonary tuberculosis requires six months of treatment. Several randomized clinical trials have attempted to shorten treatment to four months using various strategies but thus far all have failed. The PredictTB trial is an ongoing international randomized clinical trial testing a treatment shortening strategy whereby only drug-sensitive pulmonary TB patients who meet the study early treatment completion criteria are randomized to four vs. six months of treatment. The PredictTB early treatment completion criteria were developed based on a cohort of 92 pulmonary tuberculosis patients treated programmatically through the local tuberculosis treatment program in Cape Town, South Africa, with FDG-PET/CT scans also performed at baseline and week 4 of treatment. Patients were followed for one year after the end of therapy for programmatic treatment outcomes. This methodology paper describes how the PET/CT scans and GeneXpert cycle threshold data of this cohort were analyzed to develop the early treatment completion algorithm currently being used in the PredictTB trial.

Standard treatment of drug-sensitive pulmonary tuberculosis requires six months of treatment. Several randomized clinical trials have attempted to shorten treatment to four months using various strategies but thus far all have failed. The PredictTB trial is an ongoing international randomized clinical trial testing a treatment shortening strategy whereby only drug-sensitive pulmonary TB patients who meet the study early treatment completion criteria are randomized to four vs. six months of treatment. The PredictTB early treatment completion criteria were developed based on a cohort of 92 pulmonary tuberculosis patients treated programmatically through the local tuberculosis treatment program in Cape Town, South Africa, with FDG-PET/CT scans also performed at baseline and week 4 of treatment. Patients were followed for one year after the end of therapy for programmatic treatment outcomes. This methodology paper describes how the PET/CT scans and GeneXpert cycle threshold data of this cohort were analyzed to develop the early treatment completion algorithm currently being used in the PredictTB trial.

Mycobacterium tuberculosis (Mtb) is extremely recalcitrant to antimicrobial chemotherapy requiring 6 months to treat drug-sensitive tuberculosis (TB). Despite this, 4-10% of cured patients will develop recurrent disease within 12 months after completing therapy. Reasons for relapse in cured TB patients remains speculative, attributed to both pathogen and host factors. Populations of dormant bacilli are hypothesized to cause relapse in initially cured TB patients however, development of tests to convincingly demonstrate their presence at the end of anti-TB treatment has been challenging. Previous studies have indicated the utility of culture filtrate supplemented media (CFSM) to detect differentially culturable tubercle bacilli (DCTB). Here, we show that 3/22 of clinically cured patients retained DCTB in induced sputum and bronchoalveolar lavage fluid (BALF), with one DCTB positive patient relapsing within the first year of completing therapy. We also show a correlation of DCTB status with "unresolved" end of treatment FDG PET-CT imaging. Additionally, 19 end of treatment induced sputum samples from patients not undergoing bronchoscopy were assessed for DCTB, identifying a further relapse case with DCTB. We further show that induced sputum is a less reliable source for the DCTB assay at the end of treatment, limiting the utility of this assay in a clinical setting. We next investigated the host proteome at the site of disease (BALF) using multiplexed proteomic analysis and compared these to active TB cases to identify host-specific factors indicative of cure. Distinct signatures stratified active from cured TB patients into distinct groups, with a DCTB positive, subsequently relapsing, end of treatment patient showing a proteomic signature closer to active TB disease than cure. This exploratory study offers evidence of live Mtb, undetectable with conventional culture methods, at the end of clinically successful treatment and putative host protein biomarkers of active disease and cure. These findings have implications for the assessment of true sterilizing cure in TB patients and opens new avenues for targeted approaches to monitor treatment response.

Background There is a growing interest in the use of F-18 FDG PET-CT to monitor tuberculosis (TB) treatment response. Tuberculosis lung lesions are often complex and diffuse, with dynamic changes during treatment and persisting metabolic activity after apparent clinical cure. This poses a challenge in quantifying scan-based markers of burden of disease and disease activity. We used semi-automated, whole lung quantification of lung lesions to analyse serial FDG PET-CT scans from the Catalysis TB Treatment Response Cohort to identify characteristics that best correlated with clinical and microbiological outcomes. Results Quantified scan metrics were already associated with clinical outcomes at diagnosis and 1 month after treatment, with further improved accuracy to differentiate clinical outcomes after standard treatment duration (month 6). A high cavity volume showed the strongest association with a risk of treatment failure (AUC 0.81 to predict failure at diagnosis), while a suboptimal reduction of the total glycolytic activity in lung lesions during treatment had the strongest association with recurrent disease (AUC 0.8 to predict pooled unfavourable outcomes). During the first year after TB treatment lesion burden reduced; but for many patients, there were continued dynamic changes of individual lesions. Conclusions Quantification of FDG PET-CT images better characterised TB treatment outcomes than qualitative scan patterns and robustly measured the burden of disease. In future, validated metrics may be used to stratify patients and help evaluate the effectiveness of TB treatment modalities.

The evaluation of new tuberculosis (TB) therapies is limited by the paucity of biomarkers to monitor treatment response. Previous work detected an uncharacterized urine metabolite with a molecular mass of 874.3547 Da that showed promise as a biomarker for successful TB treatment. Using mass spectrometry combined with enzymatic digestions, the metabolite was structurally characterized as a seryl-leucine core 1 O-glycosylated peptide (SLC1G) of human origin. Examination of SLC1G in urine revealed a significant abundance increase in individuals with active TB versus their household contacts and healthy controls. Moreover, differential decreases in SLC1G levels were observed by week one in TB patients during successful treatment versus those that failed treatment. The SLC1G levels were also associated with clinical parameters used to measure bacterial burden (GeneXpert) and inflammation (positron emission tomography-computed tomography (PET-CT)). These results demonstrate the importance of metabolite identification and provide strong evidence for applying SLC1G as a biomarker of TB treatment response.

IMPORTANCE The World Health Organization identified the need for a non-sputum-based triage test to identify those in need of further tuberculosis (TB) testing. OBJECTIVE To determine whether the 3-gene TB score can be a diagnostic tool throughout the course of TB disease, from latency to diagnosis to treatment response, and posttreatment residual inflammation. DESIGN, SETTING, AND PARTICIPANTS This nested case-control study analyzed the 3-gene TB score in 3 cohorts, each focusing on a different stage of TB disease: (1) the Adolescent Cohort Study profiled whole-blood samples from adolescents with latent Mycobacterium tuberculosis infection, some of which progressed to active TB (ATB), using RNA sequencing; (2) the Brazil Active Screen Study collected whole blood from an actively screened case-control cohort of adult inmates from 2 prisons in Mato Grosso do Sul, Brazil, for ATB from January 2016 to February 2016; and (3) the Catalysis Treatment Response Cohort (CTRC) identified culture-positive adults in primary health care clinics in Cape Town, South Africa, from 2005 to 2007 and collected whole blood for RNA sequencing from patients with ATB at diagnosis and weeks 1, 4, and 24. The CTRC patients also had positron emission tomography-computed tomography scans at diagnosis, week 4, and week 24. Analyses were performed from September 2017 to June 2018. MAIN OUTCOMES AND MEASURES A 3-gene messenger RNA expression score, measured by quantitative polymerase chain reaction or RNA sequencing, was evaluated for distinguishing the following: individuals who progressed to ATB from those who did not, individuals with ATB from those without, and individuals with slower treatment response during TB therapy. RESULTS Patients evaluated in this study included 144 adolescents from the Adolescent Cohort Study (aged 12-18 years; 96 female and 48 male), 81 adult prison inmates from the Brazil Active Screen Study (aged 20-72 years; 81 male), and 138 adult community members from the CTRC (aged 17-64 years; 81 female and 57 male). The 3-gene TB score identified progression from latent M tuberculosis infection to ATB 6 months prior to sputum conversion with 86% sensitivity and 84% specificity (area under the curve [AUC], 0.86; 95% CI. 0.77-0.96) and patients with ATB in the Brazil Active Screen Study cohort (AUC, 0.87; 95% CI, 0.78-0.95) and CTRC (AUC, 0.94; 95% CI, 0.88-0.99). It also identified CTRC patients with failed treatment at the end of treatment (AUC. 0.93; 95% CI, 0.83-1.00). Collectively, across all cohorts, the 3-gene TB score identified patients with ATB with 90% sensitivity, 70% specificity. and 99.3% negative predictive value at 4% prevalence. CONCLUSIONS AND RELEVANCE Across 3 independent prospective cohorts, the 3-gene TB score approaches the World Health Organization target product profile benchmarks for non-sputum- based triage test with high negative predictive value. This gene expression diagnostic approach should be considered for further validation and future implementation.

The spelling of author Qianting Yang was corrected; the affiliation of author Stephanus T. Malherbe was corrected; and graphs in Fig. 4b and c were corrected owing to reanalysis of the data into the correct timed intervals.

Abstract Background Current Phase 2a methods in tuberculosis (TB) drug development are severely limited in capturing a drug candidate’s sterilizing activity (ability to prevent TB relapse). We hypothesize that sputum-based measurements of current methods fail to capture drug activity in deep TB lesion compartments, where recalcitrant TB populations are sequestered. In our recent marmoset study, we found complementary 14-day PET/CT delta signatures across different TB lesion compartments that distinguish drugs with long-term sterilizing activity (e.g., rifampin and pyrazinamide) versus drugs with primarily early bactericidal activity (e.g., isoniazid) (Figure 1). We proceeded to evaluate this novel PET/CT Phase 2a approach among TB patients, benchmarked by drugs that are well-characterized clinically and pharmacokinetically. Methods HIV-negative patients with smear-positive pulmonary tuberculosis from Cape Town, South Africa were enrolled and randomized to receive a single drug [isoniazid (H), rifampin (R), pyrazinamide (Z), moxifloxacin (M)], a 2-drug regimen (HZ, RZ), or a 4-drug regimen (HRZE, MRZE) for 14 days in an inpatient facility. Primary data points were PET/CT scans evaluated at pretreatment baseline and treatment day 14 (and day 28 in the HRZE arm), and daily overnight sputum for early bactericidal activity measurements. Results From December 2015 to September 2017, 160 participants completed the study, from whom 340 PET/CT scans and 2,238 overnight sputum samples were collected. PET/CT scans from participants demonstrate diversity of lesion architecture and inter-individual variation in PET/CT changes over 14 days of treatment (Figure 2). A preliminary computational algorithm and first- and second-order PET/CT statistics have been developed for initial segmentation and TB lesion categorization of all study scans. Derivation of radiologic signatures by analysis of 14-day PET/CT changes across each lesion type is ongoing; blinded prediction of each participant’s treatment arm based on these signatures is expected by third-quarter 2018. Conclusion If successful, these signatures may be applied within a 14-day Phase 2a framework to evaluate new TB drug candidates and construct TB drug regimens with complementary lesion pharmacokinetics. Disclosures All authors: No reported disclosures.

Background: There is a growing interest in the use of 18F-FDG PET-CT to monitor tuberculosis (TB) treatment response. However, TB causes complex and widespread pathology, which is challenging to segment and quantify in a reproducible manner. To address this, we developed a technique to standardise uptake (Z-score), segment and quantify tuberculous lung lesions on PET and CT concurrently, in order to track changes over time. We used open source tools and created a MATLAB script. The technique was optimised on a training set of five pulmonary tuberculosis (PTB) cases after standard TB therapy and 15 control patients with lesion-free lungs. Results: We compared the proposed method to a fixed threshold (SUV > 1) and manual segmentation by two readers and piloted the technique successfully on scans of five control patients and five PTB cases (four cured and one failed treatment case), at diagnosis and after 1 and 6 months of treatment. There was a better correlation between the Z-score-based segmentation and manual segmentation than SUV > 1 and manual segmentation in terms of overall spatial overlap (measured in Dice similarity coefficient) and specificity (1 minus false positive volume fraction). However, SUV > 1 segmentation appeared more sensitive. Both the Z-score and SUV > 1 showed very low variability when measuring change over time. In addition, total glycolytic activity, calculated using segmentation by Z-score and lesion-to-background ratio, correlated well with traditional total glycolytic activity calculations. The technique quantified various PET and CT parameters, including the total glycolytic activity index, metabolic lesion volume, lesion volumes at different CT densities and combined PET and CT parameters. The quantified metrics showed a marked decrease in the cured cases, with changes already apparent at month one, but remained largely unchanged in the failed treatment case. Conclusions: Our technique is promising to segment and quantify the lung scans of pulmonary tuberculosis patients in a semi-automatic manner, appropriate for measuring treatment response. Further validation is required in larger cohorts.