Nebulised interferon-ß1a (SNG001) in hospitalised COVID-19: SPRINTER phase III study.

Background: Despite the availability of vaccines and therapies, patients are being hospitalised with coronavirus disease 2019 (COVID-19). Interferon (IFN)-ß is a naturally occurring protein that stimulates host immune responses against most viruses, including severe acute respiratory syndrome coronavirus 2. SNG001 is a recombinant IFN-ß1a formulation delivered to the lungs via nebuliser. SPRINTER assessed the efficacy and safety of SNG001 in adults hospitalised due to COVID-19 who required oxygen via nasal prongs or mask. Methods: Patients were randomised double-blind to SNG001 (n=309) or placebo (n=314) once daily for 14 days plus standard of care (SoC). The primary objective was to evaluate recovery after administration of SNG001 versus placebo, in terms of times to hospital discharge and recovery to no limitation of activity. Key secondary end-points were progression to severe disease or death, progression to intubation or death and death. Results: Median time to hospital discharge was 7.0 and 8.0 days with SNG001 and placebo, respectively (hazard ratio (HR) 1.06 (95% CI 0.89-1.27); p=0.51); time to recovery was 25.0 days in both groups (HR 1.02 (95% CI 0.81-1.28); p=0.89). There were no significant SNG001-placebo differences for the key secondary end-points, with a 25.7% relative risk reduction in progression to severe disease or death (10.7% and 14.4%, respectively; OR 0.71 (95% CI 0.44-1.15); p=0.161). Serious adverse events were reported by 12.6% and 18.2% patients with SNG001 and placebo, respectively. Conclusions: Although the primary objective of the study was not met, SNG001 had a favourable safety profile, and the key secondary end-points analysis suggested that SNG001 may have prevented progression to severe disease.

Increase in recruitment upon integration of trial into a clinical care pathway: an observational study.

INTRODUCTION: Many respiratory clinical trials fail to reach their recruitment target and this problem exacerbates existing funding issues. Integration of the clinical trial recruitment process into a clinical care pathway (CCP) may represent an effective way to significantly increase recruitment numbers. METHODS: A respiratory support unit and a CCP for escalation of patients with severe COVID-19 were established on 11 January 2021. The recruitment process for the Randomised Evaluation of COVID-19 Therapy-Respiratory Support trial was integrated into the CCP on the same date. Recruitment data for the trial were collected before and after integration into the CCP. RESULTS: On integration of the recruitment process into a CCP, there was a significant increase in recruitment numbers. Fifty patients were recruited over 266 days before this process occurred whereas 108 patients were recruited over 49 days after this process. There was a statistically significant increase in both the proportion of recruited patients relative to the number of COVID-19 hospital admissions (change from 2.8% to 9.1%, p<0.0001) and intensive therapy unit admissions (change from 17.8% to 50.2%, p<0.001) over the same period, showing that this increase in recruitment was independent of COVID-19 prevalence. DISCUSSION: Integrating the trial recruitment process into a CCP can significantly boost recruitment numbers. This represents an innovative model that can be used to maximise recruitment without impacting on the financial and labour costs associated with the running of a respiratory clinical trial.

Frequencies of region of difference 1 antigen-specific but not purified protein derivative-specific gamma interferon-secreting T cells correlate with the presence of tuberculosis disease but do not distinguish recent from remote latent infections.

The majority of individuals infected with Mycobacterium tuberculosis achieve lifelong immune containment of the bacillus. What constitutes this effective host immune response is poorly understood. We compared the frequencies of gamma interferon (IFN-gamma)-secreting T cells specific for five region of difference 1 (RD1)-encoded antigens and one DosR-encoded antigen in 205 individuals either with active disease (n = 167), whose immune responses had failed to contain the bacillus, or with remotely acquired latent infection (n = 38), who had successfully achieved immune control, and a further 149 individuals with recently acquired asymptomatic infection. When subjects with an IFN-gamma enzyme-linked immunospot (ELISpot) assay response to one or more RD1-encoded antigens were analyzed, T cells from subjects with active disease recognized more pools of peptides from these antigens than T cells from subjects with nonrecent latent infection (P = 0.002). The T-cell frequencies for peptide pools were greater for subjects with active infection than for subjects with nonrecent latent infection for summed RD1 peptide pools (P 6 months) latent infection did not differ in numbers of peptide pools recognized, proportions recognizing any individual antigen or peptide pool, or antigen-specific T-cell frequencies (P >or= 0.11). The hierarchy of immunodominance for different antigens was purified protein derivative (PPD) > CFP-10 > early secretory antigenic target 6 > Rv3879c > Rv3878 > Rv3873 > Acr1, and the hierarchies were very similar for active and remotely acquired latent infections. Responses to the DosR antigen alpha-crystallin were not associated with latency (P = 0.373). In contrast to the RD1-specific responses, the responses to PPD were not associated with clinical status (P > 0.17) but were strongly associated with positive tuberculin skin test results (>or=15-mm induration; P

Use of T cell-based diagnosis of tuberculosis infection to optimize interpretation of tuberculin skin testing for child tuberculosis contacts.

BACKGROUND: Treatment of recent tuberculosis infection in children aged <2 years is essential, because of high risk of progression to disease, but diagnosis is hindered by the inaccuracy of the tuberculin skin test (TST). More-accurate T cell-based tests of infection could enhance diagnosis by optimizing interpretation of the TST results. METHODS: A total of 979 child tuberculosis contacts in Istanbul underwent the TST and enzyme-linked immunospot assay. Using enzyme-linked immunospot test results as a reference standard, we assessed the effect of age and bacille Calmette-Guérin (BCG) vaccination on the sensitivity and specificity of the TST, and we computed the optimal TST cutoff points, using receiver operating characteristic curves. RESULTS: With a TST cutoff point of >or=10 mm, the sensitivity of the TST was 66% for children aged <2 years, which was lower than that for older children (P= .006). Specificity was 75% for BCG-vaccinated children, compared with 92% for unvaccinated children (P= .001). Optimal cutoff points improved TST specificity for children with 1 BCG scar, with little loss of sensitivity. Despite the use of optimal cutoff points, TST sensitivity remained <70% for children aged <2 years, specificity remained <87% for BCG-vaccinated children aged >or=2 years, and overall accuracy was low for children with >1 BCG scar. CONCLUSIONS: Negative results of the TST cannot exclude tuberculosis infection for child tuberculosis contacts aged <2 years, which supports the use of preventive therapy regardless of the TST results for this age group. In children aged >or=2 years, the accuracy of the TST can be improved by adjustment of cutoff points for BCG-vaccinated children but remains poor for children with >1 BCG scar. This methodology can define optimal TST cutoff points for diagnosis of tuberculosis infection tailored to target populations.

Prognostic value of a T-cell-based, interferon-gamma biomarker in children with tuberculosis contact.

BACKGROUND: Enzyme-linked immunospot (ELISpot) assay is an increasingly widely used, T-cell-based, interferon-gamma-release assay for diagnosing tuberculosis infection, but whether positive results are prognostic of active tuberculosis is not known. OBJECTIVE: To determine whether ELISpot results predict the development of active tuberculosis among persons with recent tuberculosis exposure. DESIGN: Longitudinal cohort study of children and adolescents with tuberculosis contact recruited from October 2002 to April 2004. SETTING: Community-based contact investigations in Turkey. PATIENTS: 908 children and adolescents with recent household tuberculosis exposure. INTERVENTION: Enzyme-linked immunospot assay, incorporating early secretory antigenic target-6 and culture filtrate protein-10, and tuberculin skin test were done at baseline. MEASUREMENTS: Incidence rates ratios of progression to active tuberculosis for contacts with positive tuberculin skin test and ELISpot results, and relative incidence rates comparing contacts with positive and negative test results. RESULTS: Isoniazid preventive therapy was given to 688 (76%) contacts according to local guidelines. Fifteen contacts developed active tuberculosis over 1201 person-years of follow-up. Of 381 contacts with positive ELISpot results, 11 developed active tuberculosis over 536 person-years of follow-up (incidence rate, 21 per 1000 person-years [95% CI, 10.2 to 36.7 per 1000 person-years]), a statistically significant 3- to 4-fold increased risk for progression relative to ELISpot-negative contacts. Of 550 contacts with positive tuberculin skin test results, 12 developed active tuberculosis over 722 person-years of follow-up (incidence rate, 17 per 1000 person-years [CI, 8.6 to 29.0 per 1000 person-years]). LIMITATION: Only 3 of the 15 incident cases were confirmed by culture. CONCLUSION: Positive ELISpot results predict subsequent development of active tuberculosis in recent tuberculosis contacts. Although tuberculosis contacts with positive ELISpot results have an incidence rate of tuberculosis similar to that of contacts with positive tuberculin skin test results, ELISpot testing could allow more focused targeting of preventive therapy to fewer contacts.

Improved diagnostic evaluation of suspected tuberculosis.

BACKGROUND: The role of new T-cell-based blood tests for tuberculosis in the diagnosis of active tuberculosis is unclear. OBJECTIVE: To compare the performance of 2 interferon-gamma assays and tuberculin skin testing in adults with suspected tuberculosis. DESIGN: Prospective study conducted in routine practice. SETTING: 2 urban hospitals in the United Kingdom. PATIENTS: 389 adults, predominantly of South Asian and black ethnicity, with moderate to high clinical suspicion of active tuberculosis. INTERVENTION: Tuberculin skin testing, the enzyme-linked immunospot assay (ELISpot) incorporating early secretory antigenic target-6 and culture filtrate protein-10 (standard ELISpot), and ELISpot incorporating a novel antigen, Rv3879c (ELISpot(PLUS)) were performed during diagnostic assessment by independent persons who were blinded to results of the other test. MEASUREMENTS: Sensitivity, specificity, predictive values, and likelihood ratios. RESULTS: 194 patients had a final diagnosis of active tuberculosis, of which 79% were culture-confirmed. Sensitivity for culture confirmed and highly probable tuberculosis was 89% (95% CI, 84% to 93%) with ELISpot(PLUS), 85% (CI, 79% to 90%) with standard ELISpot, 79% (CI, 72% to 85%) with 15-mm threshold tuberculin skin testing, and 83% (CI, 77% to 89%) with stratified thresholds of 15 and 10 mm in vaccinated and unvaccinated patients, respectively. The ELISpot(PLUS) assay was more sensitive than tuberculin skin testing with 15-mm cutoff points (P = 0.01) but not with stratified cutoff points (P = 0.10). The ELISpot(PLUS) assay had 4% higher diagnostic sensitivity than standard ELISpot (P = 0.02). Combined sensitivity of ELISpot(PLUS) and tuberculin skin testing was 99% (CI, 95% to 100%), conferring a negative likelihood ratio of 0.02 (CI, 0 to 0.06) when both test results were negative. LIMITATIONS: Local standards for tuberculin skin testing differed from others used internationally. The study sample included few immunosuppressed patients. CONCLUSION: The ELISpot(PLUS) assay is more sensitive than standard ELISpot and, when used in combination with tuberculin skin testing, enables rapid exclusion of active infection in patients with moderate to high pretest probability of tuberculosis.

Novel M tuberculosis antigen-specific T-cells are early markers of infection and disease progression.

BACKGROUND: Mycobacterium tuberculosis Region-of-Difference-1 gene products present opportunities for specific diagnosis of M. tuberculosis infection, yet immune responses to only two gene-products, Early Secretory Antigenic Target-6 (ESAT-6) and Culture Filtrate Protein-10 (CFP-10), have been comprehensively investigated. METHODS: T-cell responses to Rv3873, Rv3878 and Rv3879c were quantified by IFN-γ-enzyme-linked-immunospot (ELISpot) in 846 children with recent household tuberculosis exposure and correlated with kinetics of tuberculin skin test (TST) and ESAT-6/CFP-10-ELISpot conversion over six months and clinical outcome over two years. RESULTS: Responses to Rv3873, Rv3878, and Rv3879c were present in 20-25% of contacts at enrolment. Rv3873 and Rv3879c responses were associated with and preceded TST conversion (P=0.02 and P=0.04 respectively), identifying these antigens as early targets of cell-mediated immunity following M. tuberculosis exposure. Responses to Rv3873 were additionally associated with subsequent ESAT-6/CFP-10-ELISpot conversion (P=0.04). Responses to Rv3873 and Rv3878 predicted progression to active disease (adjusted incidence rate ratio [95% CI] 3.06 [1.05,8.95; P=0.04], and 3.32 [1.14,9.71; P=0.03], respectively). Presence of a BCG-vaccination scar was associated with a 67% (P=0.03) relative risk reduction for progression to active tuberculosis. CONCLUSIONS: These RD1-derived antigens are early targets of cellular immunity following tuberculosis exposure and T-cells specific for these antigens predict progression to active tuberculosis suggesting diagnostic and prognostic utility.

Dynamic relationship between IFN-gamma and IL-2 profile of Mycobacterium tuberculosis-specific T cells and antigen load.

Distinct IFN-gamma and IL-2 profiles of Ag-specific CD4(+) T cells have recently been associated with different clinical disease states and Ag loads in viral infections. We assessed the kinetics and functional profile of Mycobacterium tuberculosis Ag-specific T cells secreting IFN-gamma and IL-2 in 23 patients with untreated active tuberculosis when bacterial and Ag loads are high and after curative treatment, when Ag load is reduced. The frequencies of M. tuberculosis Ag-specific IFN-gamma-secreting T cells declined during 28 mo of follow-up with an average percentage decline of 5.8% per year (p = 0.005), while the frequencies of Ag-specific IL-2-secreting T cells increased during treatment (p = 0.02). These contrasting dynamics for the two cytokines led to a progressive convergence of the frequencies of IFN-gamma- and IL-2-secreting cells over 28 mo. Simultaneous measurement of IFN-gamma and IL-2 secretion at the single-cell level revealed a codominance of IFN-gamma-only secreting and IFN-gamma/IL-2 dual secreting CD4(+) T cells in active disease that shifted to dominance of IFN-gamma/IL-2-secreting CD4(+) T cells and newly detectable IL-2-only secreting CD4(+) T cells during and after treatment. These distinct T cell functional signatures before and after treatment suggest a novel immunological marker of mycobacterial load and clinical status in tuberculosis that now requires validation in larger prospective studies.