Repurposing of anti-malarial drugs for the treatment of tuberculosis: realistic strategy or fanciful dead end?

BACKGROUND: Drug repurposing offers a strategic alternative to the development of novel compounds, leveraging the known safety and pharmacokinetic profiles of medications, such as linezolid and levofloxacin for tuberculosis (TB). Anti-malarial drugs, including quinolones and artemisinins, are already applied to other diseases and infections and could be promising for TB treatment. METHODS: This review included studies on the activity of anti-malarial drugs, specifically quinolones and artemisinins, against Mycobacterium tuberculosis complex (MTC), summarizing results from in vitro, in vivo (animal models) studies, and clinical trials. Studies on drugs not primarily developed for TB (doxycycline, sulfonamides) and any novel developed compounds were excluded. Analysis focused on in vitro activity (minimal inhibitory concentrations), synergistic effects, pre-clinical activity, and clinical trials. RESULTS: Nineteen studies, including one ongoing Phase 1 clinical trial, were analysed: primarily investigating quinolones like mefloquine and chloroquine, and, to a lesser extent, artemisinins. In vitro findings revealed high MIC values for anti-malarials versus standard TB drugs, suggesting a limited activity. Synergistic effects with anti-TB drugs were modest, with some synergy observed in combinations with isoniazid or pyrazinamide. In vivo animal studies showed limited activity of anti-malarials against MTC, except for one study of the combination of chloroquine with isoniazid. CONCLUSIONS: The repurposing of anti-malarials for TB treatment is limited by high MIC values, poor synergy, and minimal in vivo effects. Concerns about potential toxicity at effective dosages and the risk of antimicrobial resistance, especially where TB and malaria overlap, further question their repurposing. These findings suggest that focusing on novel compounds might be both more beneficial and rewarding.

Age-related changes in plasma biomarkers and their association with mortality in COVID-19.

BACKGROUND: Coronavirus disease 2019 (COVID-19)-induced mortality occurs predominantly in older patients. Several immunomodulating therapies seem less beneficial in these patients. The biological substrate behind these observations is unknown. The aim of this study was to obtain insight into the association between ageing, the host response and mortality in patients with COVID-19. METHODS: We determined 43 biomarkers reflective of alterations in four pathophysiological domains: endothelial cell and coagulation activation, inflammation and organ damage, and cytokine and chemokine release. We used mediation analysis to associate ageing-driven alterations in the host response with 30-day mortality. Biomarkers associated with both ageing and mortality were validated in an intensive care unit and external cohort. RESULTS: 464 general ward patients with COVID-19 were stratified according to age decades. Increasing age was an independent risk factor for 30-day mortality. Ageing was associated with alterations in each of the host response domains, characterised by greater activation of the endothelium and coagulation system and stronger elevation of inflammation and organ damage markers, which was independent of an increase in age-related comorbidities. Soluble tumour necrosis factor receptor 1, soluble triggering receptor expressed on myeloid cells 1 and soluble thrombomodulin showed the strongest correlation with ageing and explained part of the ageing-driven increase in 30-day mortality (proportion mediated: 13.0%, 12.9% and 12.6%, respectively). CONCLUSIONS: Ageing is associated with a strong and broad modification of the host response to COVID-19, and specific immune changes likely contribute to increased mortality in older patients. These results may provide insight into potential age-specific immunomodulatory targets in COVID-19.

High Rates of Recurrent Tuberculosis Disease: A Population-level Cohort Study.

BACKGROUND: Retreatment tuberculosis (TB) disease is common in high-prevalence settings. The risk of repeated episodes of recurrent TB is unknown. We calculated the rate of recurrent TB per subsequent episode by matching individual treatment episodes over a period of 13 years. METHODS: All recorded TB episodes in Cape Town between 2003 and 2016 were matched by probabilistic linkage of personal identifiers. Among individuals with a first episode notified in Cape Town and who completed their prior treatment successfully we estimated the recurrence rate stratified by subsequent episode and HIV status. We adjusted person-time to background mortality by age, sex, and HIV status. RESULTS: A total of 292 915 TB episodes among 263 848 individuals were included. The rate of recurrent TB was 16.4 per 1000 person-years (95% CI, 16.2-16.6), and increased per subsequent episode (8.4-fold increase, from 14.6 to 122.7 per 1000 from episode 2 to 6, respectively). These increases were similar stratified by HIV status. Rates among HIV positives were higher than among HIV negatives for episodes 2 and 3 (2- and 1.5-fold higher, respectively), and the same thereafter. CONCLUSIONS: TB recurrence rates were high and increased per subsequent episode, independent of HIV status. This suggests that HIV infection is insufficient to explain the high burden of recurrence; it is more likely due to a high annual risk of infection combined with an increased risk of infection or progression to disease associated with a previous TB episode. The very high recurrence rates would justify increased TB surveillance of patients with >1 episode.

Effect of TB/HIV Integration on TB and HIV Indicators in Rural Ugandan Health Facilities.

BACKGROUND: The World Health Organization recommends integrating services for patients coinfected with tuberculosis (TB) and HIV. We assessed the effect of TB/HIV integration on antiretroviral therapy (ART) initiation and TB treatment outcomes among TB/HIV-coinfected patients using data collected from 14 rural health facilities during 2 previous TB and HIV quality of care studies. METHODS: A facility was considered to have integrated TB/HIV services if patients with TB/HIV had combined treatment for both illnesses by 1 provider or care team at 1 treatment location. We analyzed the effect of integration by conducting a cross-sectional analysis of integrated and nonintegrated facility periods comparing performance on ART initiation and TB treatment outcomes. We conducted logistic regression, with the patient as the unit of analysis, controlling for other intervention effects, adjusting for age and sex, and clustering by health facility. RESULTS: From January 2012 to June 2014, 996 patients with TB were registered, 97% were tested for HIV, and 404 (42%) were HIV-positive. Excluding transfers, 296 patients were eligible for analysis with 117 and 179 from nonintegrated and integrated periods, respectively. Being treated in a facility with TB/HIV integration was associated with lower mortality [adjusted odds ratio (aOR) = 0.38, 95% confidence interval (CI): 0.18 to 0.77], but there was no difference in the proportion initiating ART (aOR = 1.34, 95% CI: 0.40 to 4.47), with TB treatment success (aOR = 1.43, 95% CI: 0.73 to 2.82), lost to follow-up (aOR = 1.64, 95% CI: 0.53 to 5.04), or failure (aOR = 1.21, 95% CI: 0.34 to 4.32). CONCLUSIONS: TB/HIV service integration was associated with lower mortality during TB treatment even in settings with suboptimal proportions of patients completing TB treatment and starting on ART.

Text messaging to decrease tuberculosis treatment attrition in TB-HIV coinfection in Uganda.

BACKGROUND: Low tuberculosis (TB) treatment completion rates in sub-Saharan Africa are an important driver of multidrug resistance. Mobile technology-based interventions have been shown to improve adherence to antiretroviral therapy in sub-Saharan Africa. We aimed to test the effect of a short-message service (SMS) intervention on loss to follow-up (LFU). MATERIALS AND METHODS: In this quasi-experimental study, all adult, literate, HIV-infected patients with mobile phone access diagnosed with TB between November 2010 and October 2011 in an urban clinic in Uganda were eligible to receive adherence and appointment reminders and educational quizzes during the first 8 weeks of TB treatment. Their risk of LFU in the first 8 weeks of treatment was compared with that of patients starting treatment between March 2009 and August 2010 using logistic regression. RESULTS: One of 183 (0.5%) enrolled patients was lost to FU during the intervention compared to six of 302 (2.0%) in the preintervention control group (RR 0.27, 95% CI 0.03-2.07; P=0.22). The SMS intervention was rated as very helpful by 96%. Barriers identified included interrupted phone access (26%, median 14 days) and difficulties responding by SMS. The response rate to educational quizzes was below 10%. There were no unintentional disclosures of TB or HIV status due to the intervention. CONCLUSION: An SMS reminder service did not show a clear effect on short-term risk of LFU in this study, which was underpowered due to a lower baseline risk in the control group than expected. The SMS-reminder service was rated highly, and there were no breaches of confidentiality. Important technological barriers have implications for larger-scale implementation, not only for TB but also other disease modalities.

Treatment decisions and mortality in HIV-positive presumptive smear-negative TB in the Xpert™ MTB/RIF era: a cohort study.

BACKGROUND: The Xpert™ MTB/RIF (XP) has a higher sensitivity than sputum smear microscopy (70% versus 35%) for TB diagnosis and has been endorsed by the WHO for TB high burden countries to increase case finding among HIV co-infected presumptive TB patients. Its impact on the diagnosis of smear-negative TB in a routine care setting is unclear. We determined the change in diagnosis, treatment and mortality of smear-negative presumptive TB with routine use of Xpert MTB/RIF (XP). METHODS: Prospective cohort study of HIV-positive smear-negative presumptive TB patients during a 12-month period after XP implementation in a well-staffed and trained integrated TB/HIV clinic in Kampala, Uganda. Prior to testing clinicians were asked to decide whether they would treat empirically prior to Xpert result; actual treatment was decided upon receipt of the XP result. We compared empirical and XP-informed treatment decisions and all-cause mortality in the first year. RESULTS: Of 411 smear-negative presumptive TB patients, 175 (43%) received an XP; their baseline characteristics did not differ. XP positivity was similar in patients with a pre-XP empirical diagnosis and those without (9/29 [17%] versus 14/142 [10%], P = 0.23). Despite XP testing high levels of empirical treatment prevailed (18%), although XP results did change who ultimately was treated for TB. When adjusted for CD4 count, empirical treatment was not associated with higher mortality compared to no or microbiologically confirmed treatment. CONCLUSIONS: XP usage was lower than expected. The lower sensitivity of XP in smear-negative HIV-positive patients led experienced clinicians to use XP as a "rule-in" rather than "rule-out" test, with the majority of patients still treated empirically.

The timing of tuberculosis after isoniazid preventive therapy among gold miners in South Africa: a prospective cohort study.

BACKGROUND: The durability of isoniazid preventive therapy (IPT) in preventing tuberculosis (TB) is limited in high-prevalence settings. The underlying mechanism (reactivation of persistent latent TB or reinfection) is not known. We aimed to investigate the timing of TB incidence during and after IPT and associated risk factors in a very high TB and HIV-prevalence setting, and to compare the observed rate with a modelled estimate of TB incidence rate after IPT due to reinfection. METHODS: In a post-hoc analysis of a cluster-randomized trial of community-wide IPT among South African gold miners, all intervention arm participants that were dispensed IPT for at least one of the intended 9 months were included. An incident TB case was defined as any participant with a positive sputum smear or culture, or with a clinical TB diagnosis assigned by a senior study clinician. Crude TB incidence rates were calculated during and after IPT, overall and by follow-up time. HIV status was not available. Multivariable Cox regression was used to analyse risk factors by follow-up time after IPT. Estimates from a published mathematical model of trial data were used to calculate the average reinfection TB incidence in the first year after IPT. RESULTS: Among 18,520 participants (96% male, mean age 41 years, median follow-up 2.1 years), 708 developed TB. The TB incidence rate during the intended IPT period was 1.3/100 person-years (pyrs; 95% confidence interval (CI), 1.0-1.6) and afterwards 2.3/100 pyrs (95% CI, 1.9-2.7). TB incidence increased within 6 months followed by a stable rate over time. There was no evidence for changing risk factors for TB disease over time after miners stopped IPT. The average TB incidence rate attributable to reinfection in the first year was estimated at 1.3/100 pyrs, compared to an observed rate of 2.2/100 pyrs (95% CI, 1.8-2.7). CONCLUSIONS: The durability of protection by IPT was lost within 6-12 months in this setting with a high HIV prevalence and a high annual risk of M. tuberculosis infection. The observed rate was higher than the modelled rate, suggesting that reactivation of persistent latent infection played a role in the rapid return to baseline TB incidence.

Antiretroviral therapy and tuberculosis: does the regimen matter?

Infection with HIV is one of the strongest drivers of the incidence of tuberculosis. The use of potent combination antiretroviral therapy (cART) decreases the incidence of tuberculosis in HIV-infected patients. Data on whether this effect differs by type of initial antiretroviral drug or regimen are scarce. Studies are often not designed to address the potential effect of cART on tuberculosis incidence, and/or the diagnosis of tuberculosis is poorly validated. The paucity of data precludes recommendation on the initial cART regimen with respect to the incidence tuberculosis. Other well-described intervention like preventive therapy, and early start with cART are likely to have more effect on the prevention on tuberculosis in HIV-infected patients.

Risk of tuberculosis after antiretroviral treatment initiation: a comparison between efavirenz and nevirapine using inverse probability weighting.

BACKGROUND: There is a high incidence of tuberculosis (TB) early after antiretroviral therapy (ART) initiation. This historical cohort study evaluated the association of efavirenz (EFV) compared to nevirapine (NVP) with post-ART TB among patients initiated on first-line ART from 2005 to 2009 in a large, urban HIV clinic in Uganda. METHODS: Hazard ratios (HR) for developing TB were computed using multivariable Cox proportional hazards models with inverse weighting of the probability of being prescribed NVP or EFV (calculated by a multivariable logistic regression model), stratifying by baseline CD4+ T-cell count. Adjustment for time-updated CD4+ T-cell count, restriction of the analysis to patients remaining in follow-up and a TB-free survival analysis were performed as sensitivity analyses. RESULTS: ART was initiated in 5,797 patients; 66% were women with a mean age of 37 years (SD 9) and a median baseline CD4+ T-cell count of 117 cells/mm3 (IQR 43-182). Overall, 60% (n = 3,484) were initiated on NVP and 40% (n = 2,313) on EFV. In the first 2 years of ART, 377 patients developed TB. The use of EFV compared to NVP was independently associated with higher TB incidence in patients with a baseline CD4+ T-cell count < 100 cells/mm3 (HR 2.05 [95% CI 1.29, 3.27]; P = 0.003), but not at higher CD4+ T-cell counts (HR 0.71 [95% CI 0.39, 1.31]; P = 0.428). These estimates were robust to all sensitivity analyses. CONCLUSIONS: There was a higher incidence of TB in patients with baseline CD4+ T-cell counts < 100 cells/mm3 initiated on EFV compared to those initiated on NVP. Further research in a trial setting or a larger multisite observational cohort is needed to confirm these findings.

Unrecognised tuberculosis at antiretroviral therapy initiation is associated with lower CD4+ T cell recovery.

OBJECTIVES: To investigate whether an unrecognised diagnosis of tuberculosis (TB) at the start of antiretroviral therapy (ART) influences subsequent CD4+ T cell (CD4) count recovery in an urban HIV clinic in Uganda. METHODS: In a retrospective cohort study, a multivariable polynomial mixed effects model was used to estimate CD4 recovery in the first 96 weeks of ART in two groups of patients: prevalent TB (started ART while on TB treatment), unrecognised TB (developed TB within 6 months after start ART). RESULTS: Included were 511 patients with a median baseline CD4 count of 57 cells/mm(3) (interquartile range: 22-130), of whom 368 (72%) had prevalent TB and 143 (28%) had unrecognised TB. Compared with prevalent TB, unrecognised TB was associated with lower CD4 count recovery at 96 weeks: -22.3 cells/mm(3) (95% confidence interval -43.2 to -1.5, P = 0.036). These estimates were adjusted for gender, age, baseline CD4 count and the use of zidovudine-based regimen. CONCLUSIONS: Unrecognised TB at the time of ART initiation resulted in impaired CD4 recovery compared with TB treated before ART initiation. More vigilant screening with more sensitive and rapid TB diagnostics prior to ART initiation is needed to decrease the risk of ART-associated TB and sub-optimal immune reconstitution.

Rifampicin for continuation phase tuberculosis treatment in Uganda: a cost-effectiveness analysis.

BACKGROUND: In Uganda, isoniazid plus ethambutol is used for 6 months (6HE) during the continuation treatment phase of new tuberculosis (TB) cases. However, the World Health Organization (WHO) recommends using isoniazid plus rifampicin for 4 months (4HR) instead of 6HE. We compared the impact of a continuation phase using 6HE or 4HR on total cost and expected mortality from the perspective of the Ugandan national health system. METHODOLOGY/PRINCIPAL FINDINGS: Treatment costs and outcomes were determined by decision analysis. Median daily drug price was US$0.115 for HR and US$0.069 for HE. TB treatment failure or relapse and mortality rates associated with 6HE vs. 4HR were obtained from randomized trials and systematic reviews for HIV-negative (46% of TB cases; failure/relapse -6HE: 10.4% vs. 4HR: 5.2%; mortality -6HE: 5.6% vs. 4HR: 3.5%) and HIV-positive patients (54% of TB cases; failure or relapse -6HE: 13.7% vs. 4HR: 12.4%; mortality -6HE: 16.6% vs. 4HR: 10.5%). When the initial treatment is not successful, retreatment involves an additional 8-month drug-regimen at a cost of $110.70. The model predicted a mortality rate of 13.3% for patients treated with 6HE and 8.8% for 4HR; average treatment cost per patient was predicted at $26.07 for 6HE and $23.64 for 4HR. These results were robust to the inclusion of MDR-TB as an additional outcome after treatment failure or relapse. CONCLUSIONS/SIGNIFICANCE: Combination therapy with 4HR in the continuation phase dominates 6HE as it is associated with both lower expected costs and lower expected mortality. These data support the WHO recommendation to transition to a continuation phase comprising 4HR.

Integration of HIV and TB services results in improved TB treatment outcomes and earlier prioritized ART initiation in a large urban HIV clinic in Uganda.

BACKGROUND: The World Health Organization recommends that treatment of tuberculosis (TB) in HIV-infected patients should be integrated with HIV care. In December 2008, a separate outdoor-integrated TB/HIV clinic was instituted for attendees of a large urban HIV clinic in Uganda. We sought to evaluate associated TB and HIV treatment outcomes. METHODS: Routinely collected clinical, pharmacy, and laboratory data were merged with TB clinic data for patients initiating TB treatment in 2009 and with TB register data for patients in 2007. TB treatment outcomes and (timing of) antiretroviral therapy (ART) initiation in ART-naive patients [overall and stratified by CD4+ T cell (CD4) count] in 2007 and 2009 were compared. Nosocomial transmission rates could not be assessed. RESULTS: Three hundred forty-six patients were initiated on TB treatment in 2007 and 366 in 2009. Median CD4 counts at TB diagnosis did not differ. TB treatment cure or completion increased from 62% to 68%, death or default decreased from 33% to 25% (P < 0.001). Fewer ART-naive TB patients were initiated on ART in 2009 versus 2007 (57% and 66%, P = 0.031), but this decrease was only in patients with CD4 counts >250 cells per cubic millimeter (19% vs. 48%, P = 0.003). More patients were started on ART during TB treatment (94% vs. 78%, P < 0.001). Moreover, the majority were now initiated during intensive phase (60% vs. 23%, P < 0.001). CONCLUSIONS: Integration of TB and HIV care has led to improved TB treatment outcomes and earlier, prioritized ART initiation. This supports rollout of a fully integrated TB/HIV service delivery model throughout high-prevalence TB and HIV settings.

Incident tuberculosis during antiretroviral therapy contributes to suboptimal immune reconstitution in a large urban HIV clinic in sub-Saharan Africa.

BACKGROUND: Antiretroviral therapy (ART) effectively decreases tuberculosis (TB) incidence long-term, but is associated with high TB incidence rates in the first 6 months. We sought to determine the incidence and the long-term effects of TB during ART on HIV treatment outcome, and the risk factors for incident TB during ART in a large urban HIV clinic in Uganda. METHODOLOGY/PRINCIPAL FINDINGS: Routinely collected longitudinal clinical data from all patients initiated on first-line ART was retrospectively analysed. 5,982 patients were included with a median baseline CD4+ T cell count (CD4 count) of 117 cells/mm(3) (interquartile range [IQR]; 42, 182). In the first 2 years, there were 336 (5.6%) incident TB events in 10,710 person-years (py) of follow-up (3.14 cases/100 pyar [95% CI 2.82-3.49]); incidence rates at 0-3, 3-6, 6-12 and 12-24 months were 11.25 (9.58-13.21), 6.27 (4.99-7.87), 2.47 (1.87-3.36) and 1.02 (0.80-1.31), respectively. Incident TB during ART was independently associated with baseline CD4 count of <50 cells/mm(3) (hazard ratio [HR] 1.84 [1.25-2.70], P = 0.002) and male gender (HR 1.68 [1.34-2.11], P<0.001). After two years on ART, the patients who had developed TB in the first 12 months had a significantly lower median CD4 count increase (184 cells/mm(3) [IQR; 107, 258, n = 118] vs 209 cells/mm(3) [124, 309, n = 2166], P = 0.01), a larger proportion of suboptimal immune reconstitution according to two definitions (increase in CD4 count <200 cells/mm(3): 57.4% vs 46.9%, P = 0.03, and absolute CD4 count <200 cells/mm(3): 30.4 vs 19.9%, P = 0.006), and a higher percentage of immunological failure according to the WHO criteria (13.6% vs 6.5%, P = 0.003). Incident TB during ART was independently associated with poor CD4 count recovery and fulfilling WHO immunological failure definitions. CONCLUSIONS/SIGNIFICANCE: Incident TB during ART occurs most often within 3 months and in patients with CD4 counts less than 50 cells/mm(3). Incident TB during ART is associated with long-term impairment in immune recovery.