Safety and immunogenicity of VPM1002 versus BCG in South African newborn babies: a randomised, phase 2 non-inferiority double-blind controlled trial.

BACKGROUND: Tuberculosis is a major public health problem worldwide. Immunisation with Mycobacterium bovis BCG vaccine is partially effective in infants, reducing the incidence of miliary and tuberculosis meningitis, but is less effective against pulmonary tuberculosis. We aimed to compare safety and immunogenicity of VPM1002-a recombinant BCG vaccine developed to address this gap-with BCG in HIV exposed and HIV unexposed newborn babies. METHODS: This double-blind, randomised, active controlled phase 2 study was conducted at four health centres in South Africa. Eligible neonates were aged 12 days or younger with a birthweight of 2·5-4·2 kg, and could be HIV exposed (seropositive mothers) or unexposed (seronegative mothers). Newborn babies were excluded if they had acute or chronic illness, fever, hypothermia, sepsis, cancer, or congenital malformation, or if they received blood products or immunosuppressive therapy. Participants were excluded if their mothers (aged ≥18 years) had active tuberculosis disease, diabetes, a history of immunodeficiency except for HIV, hepatitis B or syphilis seropositivity, received blood products in the preceding 6 months, any acute infectious disease, or any suspected substance abuse. Participants were randomly assigned to VPM1002 or BCG vaccination in a 3:1 ratio, stratified by HIV status using the random number generator function in SAS, using a block size of eight paticipants. The primary outcome was non-inferiority (margin 15%) of VPM1002 to BCG vaccine in terms of incidence of grade 3-4 adverse drug reactions or ipsilateral or generalised lymphadenopathy of 10 mm or greater in diameter by 12 months. The primary outcome was assessed in all vaccinated participants (safety population) at regular follow-up visits until 12 months after vaccination. Secondary immunogenicity outcomes were interferon-γ levels and percentages of multifunctional CD4+ and CD8+ T cells among all lymphocytes across the 12 month study period. The study was registered with ClinicalTrials.gov, NCT02391415. FINDINGS: Between June 4, 2015 and Oct 16, 2017, 416 eligible newborn babies were randomly assigned and received study vaccine. Seven (2%) of 312 participants in the VPM1002 group had a grade 3-4 vaccine-related adverse reaction or lymphadenopathy of 10 mm or greater in diameter compared with 34 (33%) of 104 participants in the BCG group (risk difference -30·45% [95% CI -39·61% to -21·28%]; pnon-inferiority<0·0001); VPM1002 was thus non-inferior to BCG for the primary outcome. Incidence of severe injection site reactions was lower with VPM1002 than BCG: scarring occurred in 65 (21%) participants in the VPM1002 group versus 77 (74%) participants in the BCG group (p<0·0001); ulceration occurred in one (<1%) versus 15 (14%; p<0·0001); and abscess formation occurred in five (2%) versus 23 (22%; p<0·0001). Restimulated IFNγ concentrations were lower in the VPM1002 group than the BCG group at week 6, week 12, month 6, and month 12. The percentage of multifunctional CD4+ T cells was higher in the VPM1002 group than the BCG group at day 14 but lower at week 6, week 12, month 6, and month 12. The percentage of multifunctional CD8+ T cells was lower in the VPM1002 group than the BCG group at week 6, week 12, and month 6, but did not differ at other timepoints. INTERPRETATION: VPM1002 was less reactogenic than BCG and was not associated with any serious safety concern. Both vaccines were immunogenic, although responses were higher with the BCG vaccine. VPM1002 is currently being studied for efficacy and safety in a multicentric phase 3 clinical trial in babies in sub-Saharan Africa. FUNDING: Serum Institute of India.

The effect of host factors on discriminatory performance of a transcriptomic signature of tuberculosis risk.

BACKGROUND: We aimed to understand host factors that affect discriminatory performance of a transcriptomic signature of tuberculosis risk (RISK11). METHODS: HIV-negative adults aged 18-60 years were evaluated in a prospective study of RISK11 and surveilled for tuberculosis through 15 months. Generalised linear models and receiver-operating characteristic (ROC) regression were used to estimate effect of host factors on RISK11 score (%marginal effect) and on discriminatory performance for tuberculosis disease (area under the curve, AUC), respectively. FINDINGS: Among 2923 participants including 74 prevalent and 56 incident tuberculosis cases, percentage marginal effects on RISK11 score were increased among those with prevalent tuberculosis (+18·90%, 95%CI 12·66-25·13), night sweats (+14·65%, 95%CI 5·39-23·91), incident tuberculosis (+7·29%, 95%CI 1·46-13·11), flu-like symptoms (+5·13%, 95%CI 1·58-8·68), and smoking history (+2·41%, 95%CI 0·89-3·93) than those without; and reduced in males (-6·68%, 95%CI -8·31- -5·04) and with every unit increase in BMI (-0·13%, 95%CI -0·25- -0·01). Adjustment for host factors affecting controls did not change RISK11 discriminatory performance. Cough was associated with 72·55% higher RISK11 score in prevalent tuberculosis cases. Stratification by cough improved diagnostic performance from AUC = 0·74 (95%CI 0·67-0·82) overall, to 0·97 (95%CI 0·90-1·00, p < 0·001) in cough-positive participants. Combining host factors with RISK11 improved prognostic performance, compared to RISK11 alone, (AUC = 0·76, 95%CI 0·69-0·83 versus 0·56, 95%CI 0·46-0·68, p < 0·001) over a 15-month predictive horizon. INTERPRETATION: Several host factors affected RISK11 score, but only adjustment for cough affected diagnostic performance. Combining host factors with RISK11 should be considered to improve prognostic performance. FUNDING: Bill and Melinda Gates Foundation, South African Medical Research Council.

Radiological and functional evidence of the bronchial spread of tuberculosis: an observational analysis.

BACKGROUND: Direct bronchial spread of tuberculosis was extensively described in pre-antibiotic human pathology literature but this description has been overlooked in the post-antibiotic era, in which most pathology data come from animal models that emphasise the granuloma. Modern techniques, such as [18F]2-fluoro-2-deoxy-D-glucose (FDG) PET-CT scans, might provide further insight. Our aim was to understand normal early tuberculosis resolution patterns on pulmonary PET-CT scans in treated patients with tuberculosis who were subsequently cured. METHODS: In this observational analysis, we analysed data from PredictTB, an ongoing, prospective, randomised clinical trial that examined sequential baseline and week 4 FDG-PET-CT scans from participants successfully treated (sputum culture negative 18 months after enrolment) for drug-susceptible pulmonary tuberculosis in South Africa and China. Participants who were aged 18-75 years, GeneXpert MTB/RIF positive for tuberculosis and negative for rifampicin resistance, had not yet started tuberculosis treatment, had not been treated for active tuberculosis within the previous 3 years, and met basic safety laboratory criteria were included and participants with diabetes, HIV infection, or with extrapulmonary tuberculosis including pleural tuberculosis were excluded. Scans were assessed by two readers for the location of tuberculosis lesions (eg, cavities and consolidations), bronchial thickening patterns, and changes from baseline to week 4 of treatment. FINDINGS: Among the first 124 participants (enrolled from June 22, 2017, to Sept 27, 2018) who were successfully treated, 161 primarily apical cavitary lesions were identified at baseline. Bronchial thickening and inflammation linking non-cavitary consolidative lesions to cavities were observed in 121 (98%) of 124 participants' baseline PET-CT scans. After 4 weeks of treatment, 21 (17%) of 124 participants had new or expanding lesions linked to cavities via bronchial inflammation that were not present at baseline, particularly participants with two or more cavities at baseline and participants from South Africa. INTERPRETATION: In participants with pulmonary tuberculosis who were subsequently cured, the location of cavitary and non-cavitary lesions at baseline and new lesions at week 4 of treatment suggest a cavitary origin of disease and bronchial spread through the lungs. Bronchial spread from cavities might play a larger role in the spread of pulmonary tuberculosis than has been appreciated. Elucidating cavity lesion dynamics and Mycobacterium tuberculosis viability within cavities might better explain treatment outcomes and why some patients are cured and others relapse. FUNDING: Bill & Melinda Gates Foundation, European and Developing Countries Clinical Trials Partnership, China Ministry of Science and Technology, National Natural Science Foundation of China, and National Institutes of Health. TRANSLATIONS: For the Chinese, Afrikaans and Xhosa translations of the abstract see Supplementary Materials section.

The novel tuberculosis vaccine, AERAS-402, is safe in healthy infants previously vaccinated with BCG, and induces dose-dependent CD4 and CD8T cell responses.

BACKGROUND: Efforts to reduce risk of tuberculosis disease in children include development of effective vaccines. Our aim was to test safety and immunogenicity of the new adenovirus 35-vectored tuberculosis vaccine candidate AERAS-402 in infants, administered as a boost following a prime with the Bacille Calmette-Guerin vaccine. METHODS: In a phase 1 randomised, double-blind, placebo-controlled, dose-escalation trial, BCG-vaccinated infants aged 6-9 months were sequentially assigned to four study groups, then randomized to receive an increasing dose-strength of AERAS-402, or placebo. The highest dose group received a second dose of vaccine or placebo 56 days after the first. The primary study outcome was safety. Whole blood intracellular cytokine staining assessed immunogenicity. RESULTS: Forty-two infants received AERAS-402 and 15 infants received placebo. During follow-up of 182 days, an acceptable safety profile was shown with no serious adverse events or discontinuations related to the vaccine. AERAS-402 induced a specific T cell response. A single dose of AERAS-402 induced CD4T cells predominantly expressing single IFN-γ whereas two doses induced CD4T cells predominantly expressing IFN-γ, TNF-α and IL-2 together. CD8T cells were induced and were more likely to be present after 2 doses of AERAS-402. CONCLUSIONS: AERAS-402 was safe and immunogenic in healthy infants previously vaccinated with BCG at birth. Administration of the highest dose twice may be the most optimal vaccination strategy, based on the induced immunity. Multiple differences in T cell responses when infants are compared with adults vaccinated with AERAS-402, in the same setting and using the same whole blood intracellular cytokine assay, suggest specific strategies may be important for vaccination for each population.

Process of assay selection and optimization for the study of case and control samples from a phase IIb efficacy trial of a candidate tuberculosis vaccine, MVA85A.

The first phase IIb safety and efficacy trial of a new tuberculosis vaccine since that for BCG was completed in October 2012. BCG-vaccinated South African infants were randomized to receive modified vaccinia virus Ankara, expressing the Mycobacterium tuberculosis antigen 85A (MVA85A), or placebo. MVA85A did not significantly boost the protective effect of BCG. Cryopreserved samples provide a unique opportunity for investigating the correlates of the risk of tuberculosis disease in this population. Due to the limited amount of sample available from each infant, preliminary work was necessary to determine which assays and conditions give the most useful information. Peripheral blood mononuclear cells (PBMC) were stimulated with antigen 85A (Ag85A) and purified protein derivative from M. tuberculosis in an ex vivo gamma interferon (IFN-γ) enzyme-linked immunosorbent spot assay (ELISpot) and a Ki67 proliferation assay. The effects of a 2-h or overnight rest of thawed PBMC on ELISpot responses and cell populations were determined. Both the ELISpot and Ki67 assays detected differences between the MVA85A and placebo groups, and the results correlated well. The cell numbers and ELISpot responses decreased significantly after an overnight rest, and surface flow cytometry showed a significant loss of CD4(+) and CD8(+) T cells. Of the infants tested, 50% had a positive ELISpot response to a single pool of flu, Epstein-Barr virus (EBV), and cytomegalovirus (CMV) (FEC) peptides. This pilot work has been essential in determining the assays and conditions to be used in the correlate study. Moving forward, PBMC will be rested for 2 h before assay setup. The ELISpot assay, performed in duplicate, will be selected over the Ki67 assay, and further work is needed to evaluate the effect of high FEC responses on vaccine-induced immunity and susceptibility to tuberculosis disease.

Heterologous vaccination against human tuberculosis modulates antigen-specific CD4+ T-cell function.

Heterologous prime-boost strategies hold promise for vaccination against tuberculosis. However, the T-cell characteristics required for protection are not known. We proposed that boost vaccines should induce long-lived functional and phenotypic changes to T cells primed by Bacille Calmette Guerin (BCG) and/or natural exposure to mycobacteria. We characterized changes among specific CD4(+) T cells after vaccination with the MVA85A vaccine in adults, adolescents, and children. CD4(+) T cells identified with Ag85A peptide-bearing HLA class II tetramers were characterized by flow cytometry. We also measured proliferative potential and cytokine expression of Ag85A-specific CD4(+) T cells. During the effector phase, MVA85A-induced specific CD4(+) T cells coexpressed IFN-γ and IL-2, skin homing integrins, and the activation marker CD38. This was followed by contraction and a transition to predominantly IL-2-expressing, CD45RA(-) CCR7(+) CD27(+) or CD45RA(+) CCR7(+) CD27(+) specific CD4(+) T cells. These surface phenotypes were similar to Ag85A-specific T cells prior to MVA85A. However, functional differences were observed postvaccination: specific proliferative capacity was markedly higher after 6-12 months than before vaccination. Our data suggest that MVA85A vaccination may modulate Ag85A-specific CD4(+) T-cell function, resulting in greater recall potential. Importantly, surface phenotypes commonly used as proxies for memory T-cell function did not associate with functional effects of vaccination.

Screening for TB in high school adolescents in a high burden setting in South Africa.

Screening for tuberculosis (TB) disease is important for TB control and TB vaccine efficacy trials but this has not been evaluated in adolescents. We conducted a study to determine the prevalence of active TB and performance of specific screening tests for TB in adolescents in a high burden setting. Adolescents aged 12-18 years were recruited from high schools in a rural town in South Africa. Participants were screened for active TB using symptoms, household TB contact, positive interferon gamma release assay (IGRA) and positive tuberculin skin test (TST). Of 6363 adolescents recruited, 21 were newly diagnosed with TB of whom 19 were culture positive. After exclusions, the derived prevalence of smear positive TB was 16/5682 = 3/1000 (95% confidence interval (CI) 1-4/1000). The sensitivity of TST and IGRA for active TB were 85% (95% CI 62-100%) and 94% (95% CI 79-100%) respectively. None of the methods alone or in combination had positive predictive values greater than 2%. The screening tools evaluated in this study may not be practical for routine use owing to low positive predictive values but may be useful in TB vaccine clinical trials.

A phase IIa trial of the new tuberculosis vaccine, MVA85A, in HIV- and/or Mycobacterium tuberculosis-infected adults.

RATIONALE: Novel tuberculosis (TB) vaccines should be safe and effective in populations infected with Mycobacterium tuberculosis (M.tb) and/or HIV for effective TB control. OBJECTIVE: To determine the safety and immunogenicity of MVA85A, a novel TB vaccine, among M.tb- and/or HIV-infected persons in a setting where TB and HIV are endemic. METHODS: An open-label, phase IIa trial was conducted in 48 adults with M.tb and/or HIV infection. Safety and immunogenicity were analyzed up to 52 weeks after intradermal vaccination with 5 × 10(7) plaque-forming units of MVA85A. Specific T-cell responses were characterized by IFN-γ enzyme-linked immunospot and whole blood intracellular cytokine staining assays. MEASUREMENTS AND MAIN RESULTS: MVA85A was well tolerated and no vaccine-related serious adverse events were recorded. MVA85A induced robust and durable response of mostly polyfunctional CD4(+) T cells, coexpressing IFN-γ, tumor necrosis factor-α, and IL-2. Magnitudes of pre- and postvaccination T-cell responses were lower in HIV-infected, compared with HIV-uninfected, vaccinees. No significant effect of antiretroviral therapy on immunogenicity of MVA85A was observed. CONCLUSIONS: MVA85A was safe and immunogenic in persons with HIV and/or M.tb infection. These results support further evaluation of safety and efficacy of this vaccine for prevention of TB in these target populations.

Structured approaches for the screening and diagnosis of childhood tuberculosis in a high prevalence region of South Africa.

OBJECTIVE: To measure agreement between nine structured approaches for diagnosing childhood tuberculosis; to quantify differences in the number of tuberculosis cases diagnosed with the different approaches, and to determine the distribution of cases in different categories of diagnostic certainty. METHODS: We investigated 1445 children aged < 2 years during a vaccine trial (2001-2006) in a rural South African community. Clinical, radiological and microbiological data were collected prospectively. Tuberculosis case status was determined using each of the nine diagnostic approaches. We calculated differences in case frequency and categorical agreement for binary (tuberculosis/not tuberculosis) outcomes using McNemar's test (with 95% confidence intervals, CIs) and Cohen's kappa coefficient (Kappa). FINDINGS: Tuberculosis case frequency ranged from 6.9% to 89.2% (median: 41.7). Significant differences in case frequency (P < 0.05) occurred in 34 of the 36 pair-wise comparisons between structured diagnostic approaches (range of absolute differences: 1.5-82.3%). Kappa ranged from 0.02 to 0.71 (median: 0.18). The two systems that yielded the highest case frequencies (89.2% and 70.0%) showed fair agreement (Kappa: 0.33); the two that yielded the lowest case frequencies (6.9% and 10.0%) showed slight agreement (Kappa: 0.18). CONCLUSION: There is only slight agreement between structured approaches for the screening and diagnosis of childhood tuberculosis and high variability between them in terms of case yield. Diagnostic systems that yield similarly low case frequencies may be identifying different subpopulations of children. The study findings do not support the routine clinical use of structured approaches for the definitive diagnosis of childhood tuberculosis, although high-yielding systems may be useful screening tools.

The novel tuberculosis vaccine, AERAS-402, induces robust and polyfunctional CD4+ and CD8+ T cells in adults.

RATIONALE: AERAS-402 is a novel tuberculosis vaccine designed to boost immunity primed by bacillus Calmette-Guérin (BCG), the only licensed vaccine. OBJECTIVES: We investigated the safety and immunogenicity of AERAS-402 in healthy Mycobacterium tuberculosis-uninfected BCG-vaccinated adults from a tuberculosis-endemic region of South Africa. METHODS: Escalating doses of AERAS-402 vaccine were administered intramuscularly to each of three groups of healthy South African BCG-vaccinated adults, and a fourth group received two injections of the maximal dose. Participants were monitored for 6 months, with all adverse effects documented. Vaccine-induced CD4(+) and CD8(+) T-cell immunity was characterized by an intracellular cytokine staining assay of whole blood and peripheral blood mononuclear cells. MEASUREMENTS AND MAIN RESULTS: AERAS-402 was well tolerated, and no vaccine-related serious adverse events were recorded. The vaccine induced a robust CD4(+) T-cell response dominated by cells coexpressing IFN-gamma, tumor necrosis factor-alpha, and IL-2 ("polyfunctional" cells). AERAS-402 also induced a potent CD8(+) T-cell response, characterized by cells expressing IFN-gamma and/or tumor necrosis factor-alpha, which persisted for the duration of the study. CONCLUSIONS: Vaccination with AERAS-402 is safe and immunogenic in healthy adults. The immunity induced by the vaccine appears promising: polyfunctional T cells are thought to be important for protection against intracellular pathogens such as Mycobacterium tuberculosis, and evidence is accumulating that CD8(+) T cells are also important. AERAS-402 induced a robust and durable CD8(+) T-cell response, which appears extremely promising. Clinical trial registered with www.sanctr.gov.za (NHREC no. 1381).

HIV-1 infection in infants severely impairs the immune response induced by Bacille Calmette-Guérin vaccine.

BACKGROUND: Worldwide, most infants born to mothers infected with human immunodeficiency virus (HIV) receive bacille Calmette-Guérin (BCG) vaccine. Tuberculosis is a major cause of death among infants infected with HIV in sub-Saharan Africa, and it should be prevented. However, BCG may itself cause disease (known as "BCGosis") in these infants. Information regarding the immunogenicity of BCG is imperative for the risk/benefit assessment of BCG vaccination in HIV-infected infants; however, no such data exist. METHODS: We compared BCG-induced CD4 and CD8 T cell responses, as assessed by flow cytometry, in HIV-infected (n=20), HIV-exposed but uninfected (n=25), and HIV-unexposed (n=23) infants, during their first year of life. RESULTS: BCG vaccination of the 2 HIV-uninfected groups induced a robust response, which was characterized by CD4 T cells expressing interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, and/or interleukin (IL)-2. In contrast, HIV-infected infants demonstrated a markedly lower response throughout the first year of life. These infants also had significantly reduced numbers of polyfunctional CD4 T cells coexpressing IFN-gamma, TNF-alpha, and IL-2, a finding that is thought to indicate T cell quality. CONCLUSIONS: Infection with HIV severely impairs the BCG-specific T cell response during the first year of life. BCG may therefore provide little, if any, vaccine-induced benefit in HIV-infected infants. Considering the significant risk of BCGosis, these data strongly support not giving BCG to HIV-infected infants.

Safety and immunogenicity of a new tuberculosis vaccine, MVA85A, in healthy adults in South Africa.

BACKGROUND: The efficacy of bacille Calmette-Guérin (BCG) may be enhanced by heterologous vaccination strategies that boost the BCG-primed immune response. One leading booster vaccine, MVA85A (where "MVA" denotes "modified vaccinia virus Ankara"), has shown promising safety and immunogenicity in human trials performed in the United Kingdom. We investigated the safety and immunogenicity of MVA85A in mycobacteria-exposed--but Mycobacterium tuberculosis-uninfected--healthy adults from a region of South Africa where TB is endemic. METHODS: Twenty-four adults were vaccinated with MVA85A. All subjects were monitored for 1 year for adverse events and for immunological assessment. RESULTS: MVA85A vaccination was well tolerated and induced potent T cell responses, as measured by interferon (IFN)-gamma enzyme-linked immunospot assay, which exceeded prevaccination responses up to 364 days after vaccination. BCG-specific CD4+ T cells boosted by MVA85A were comprised of multiple populations expressing combinations of IFN-gamma, tumor necrosis factor (TNF)-alpha, interleukin (IL)-2, and IL-17, as measured by polychromatic flow cytometry. IFN-gamma-expressing and polyfunctional IFN-gamma+TNF-gamma+IL-2+ CD4+ T cells were boosted during the peak BCG-specific response, which occurred 7 days after vaccination. CONCLUSION: The excellent safety profile and quantitative and qualitative immunogenicity data strongly support further trials assessing the efficacy of MVA85A as a boosting vaccine in countries where TB is endemic. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00460590.