Safety and immunogenicity of the H56:IC31 tuberculosis vaccine candidate in adults successfully treated for drug-susceptible pulmonary TB: a phase 1 randomized trial.

BACKGROUND: H56:IC31 is a candidate vaccine against tuberculosis (TB) with the potential to reduce TB recurrence rate. It is thus important for future clinical trials to demonstrate safety and immunogenicity of H56:IC31 in individuals treated for TB. METHODS: 22 adults confirmed to be Mtb negative (by 2 GeneXpert tests or 2 sputum cultures) after four-five months of TB treatment, and not more than 28 days after completion of TB treatment, were randomized to receive two doses of H56:IC31 (5 mg H56:500 nmol IC31; N=16) or placebo (N=6) 56 days apart. Participants were followed for 420 days for safety and immunogenicity. RESULTS: H56:IC31 vaccination was associated with an acceptable safety profile, consisting mostly of mild self-limited injection site reactions. No serious adverse events, and no vaccine-related severe adverse events, were reported. H56:IC31 induced a CD4+ T-cell response for Ag85B and ESAT-6, with ESAT-6 being immunodominant, which persisted through six months after the last vaccination. There was some evidence of CD8+ T-cell responses for both Ag85B and ESAT-6, but to a lesser extent than CD4+ responses. CONCLUSIONS: H56:IC31 was associated with an acceptable safety profile, and induced a predominant CD4+ T-cell response, in adults recently treated for drug-susceptible, uncomplicated pulmonary TB. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02375698.

PET CT Identifies Reactivation Risk in Cynomolgus Macaques with Latent M. tuberculosis.

Mycobacterium tuberculosis infection presents across a spectrum in humans, from latent infection to active tuberculosis. Among those with latent tuberculosis, it is now recognized that there is also a spectrum of infection and this likely contributes to the variable risk of reactivation tuberculosis. Here, functional imaging with 18F-fluorodeoxygluose positron emission tomography and computed tomography (PET CT) of cynomolgus macaques with latent M. tuberculosis infection was used to characterize the features of reactivation after tumor necrosis factor (TNF) neutralization and determine which imaging characteristics before TNF neutralization distinguish reactivation risk. PET CT was performed on latently infected macaques (n = 26) before and during the course of TNF neutralization and a separate set of latently infected controls (n = 25). Reactivation occurred in 50% of the latently infected animals receiving TNF neutralizing antibody defined as development of at least one new granuloma in adjacent or distant locations including extrapulmonary sites. Increased lung inflammation measured by PET and the presence of extrapulmonary involvement before TNF neutralization predicted reactivation with 92% sensitivity and specificity. To define the biologic features associated with risk of reactivation, we used these PET CT parameters to identify latently infected animals at high risk for reactivation. High risk animals had higher cumulative lung bacterial burden and higher maximum lesional bacterial burdens, and more T cells producing IL-2, IL-10 and IL-17 in lung granulomas as compared to low risk macaques. In total, these data support that risk of reactivation is associated with lung inflammation and higher bacterial burden in macaques with latent Mtb infection.

An investigation of trachoma vaccine regimens by the chlamydia vaccine CTH522 administered with cationic liposomes in healthy adults (CHLM-02): a phase 1, double-blind trial.

BACKGROUND: There is no vaccine against the major global pathogen Chlamydia trachomatis; its different serovars cause trachoma in the eye or chlamydia in the genital tract. We did a clinical trial administering CTH522, a recombinant version of the C trachomatis major outer membrane molecule, in different dose concentrations with and without adjuvant, to establish its safety and immunogenicity when administered intramuscularly, intradermally, and topically into the eye, in prime-boost regimens. METHODS: CHLM-02 was a phase 1, double-blind, randomised, placebo-controlled trial at the National Institute for Health Research Imperial Clinical Research Facility, London, UK. Participants were healthy men and non-pregnant women aged 18-45 years, without pre-existing C trachomatis genital infection. Participants were assigned into six groups by the electronic database in a pre-prepared randomisation list (A-F). Participants were randomly assigned (1:1:1:1:1) to each of the groups A-E (12 participants each) and 6 were randomly assigned to group F. Investigators were masked to treatment allocation. Groups A-E received investigational medicinal product and group F received placebo only. Two liposomal adjuvants were compared, CAF01 and CAF09b. The groups were intramuscular 85 µg CTH522-CAF01, or placebo on day 0 and two boosters or placebo at day 28 and 112, and a mucosal recall with either placebo or CTH522 topical ocularly at day 140 (A); intramuscular 85 µg CTH522-CAF01, two boosters at day 28 and 112 with additional topical ocular administration of CTH522, and a mucosal recall with either placebo or CTH522 topical ocularly at day 140 (B); intramuscular 85 µg CTH522-CAF01, two boosters at day 28 and 112 with additional intradermal administration of CTH522, and a mucosal recall with either placebo or CTH522 topical ocularly at day 140 (C); intramuscular 15 µg CTH522-CAF01, two boosters at day 28 and 112, and a mucosal recall with either placebo or CTH522 topical ocularly at day 140 (D); intramuscular 85 µg CTH522-CAF09b, two boosters at day 28 and 112, and a mucosal recall with either placebo or CTH522 topical ocularly at day 140 (E); intramuscular placebo (F). The primary outcome was safety; the secondary outcome (humoral immunogenicity) was the percentage of trial participants achieving anti-CTH522 IgG seroconversion, defined as four-fold and ten-fold increase over baseline concentrations. Analyses were done as intention to treat and as per protocol. The trial is registered with ClinicalTrials.gov, NCT03926728, and is complete. FINDINGS: Between Feb 17, 2020 and Feb 22, 2022, of 154 participants screened, 65 were randomly assigned, and 60 completed the trial (34 [52%] of 65 women, 46 [71%] of 65 White, mean age 26·8 years). No serious adverse events occurred but one participant in group A2 discontinued dosing after having self-limiting adverse events after both placebo and investigational medicinal product doses. Study procedures were otherwise well tolerated; the majority of adverse events were mild to moderate, with only seven (1%) of 865 reported as grade 3 (severe). There was 100% four-fold seroconversion rate by day 42 in the active groups (A-E) and no seroconversion in the placebo group. Serum IgG anti-CTH522 titres were higher after 85 µg CTH522-CAF01 than 15 µg, although not significantly (intention-to-treat median IgG titre ratio groups A-C:D=5·6; p=0·062), with no difference after three injections of 85 µg CTH522-CAF01 compared with CTH522-CAF09b (group E). Intradermal CTH522 (group C) induced high titres of serum IgG anti-CTH522 neutralising antibodies against serovars B (trachoma) and D (urogenital). Topical ocular CTH522 (group B) at day 28 and 112 induced higher total ocular IgA compared with baseline (p<0·001). Participants in all active vaccine groups, particularly groups B and E, developed cell mediated immune responses against CTH522. INTERPRETATION: CTH522, adjuvanted with CAF01 or CAF09b, is safe and immunogenic, with 85 µg CTH522-CAF01 inducing robust serum IgG binding titres. Intradermal vaccination conferred systemic IgG neutralisation breadth, and topical ocular administration increased ocular IgA formation. These findings indicate CTH522 vaccine regimens against ocular trachoma and urogenital chlamydia for testing in phase 2, clinical trials. FUNDING: The EU Horizon Program TRACVAC.

A phase 1b randomized study of the safety and immunological responses to vaccination with H4:IC31, H56:IC31, and BCG revaccination in Mycobacterium tuberculosis-uninfected adolescents in Cape Town, South Africa.

BACKGROUND: Tuberculosis (TB) remains the leading cause of infectious disease-related death. Recently, a trial of BCG revaccination and vaccination with H4:IC31, a recombinant protein vaccine, in South African adolescents (Aeras C-040-404) showed efficacy in preventing sustained QuantiFERON (QFT) conversion, a proxy for Mycobacterium tuberculosis (M.tb) infection. A phase 1b trial of 84 South African adolescents was conducted, concurrent with Aeras C-040-404, to assess the safety and immunogenicity of H4:IC31, H56:IC31 and BCG revaccination, and to identify and optimize immune assays for identification of candidate correlates of protection in efficacy trials. METHODS: Two doses of H4:IC31 and H56:IC31 vaccines were administered intramuscularly (IM) 56 days apart, and a single dose of BCG (2-8 × 105 CFU) was administered intradermally (ID). T-cell and antibody responses were measured using intracellular cytokine staining and binding antibody assays, respectively. Binding antibodies and CD4+/CD8+ T-cell responses to H4- and H56-matched antigens were measured in samples from all participants. The study was designed to characterize safety and immunogenicity and was not powered for group comparisons. (Clinicaltrials.gov NCT02378207). FINDINGS: In total, 481 adolescents (mean age 13·9 years) were screened; 84 were enrolled (54% female). The vaccines were generally safe and well-tolerated, with no reported severe adverse events related to the study vaccines. H4:IC31 and H56:IC31 elicited CD4+ T cells recognizing vaccine-matched antigens and H4- and H56-specific IgG binding antibodies. The highest vaccine-induced CD4+ T-cell response rates were for those recognizing Ag85B in the H4:IC31 and H56:IC31 vaccinated groups. BCG revaccination elicited robust, polyfunctional BCG-specific CD4+ T cells, with no increase in H4- or H56-specific IgG binding antibodies. There were few antigen-specific CD8+ T-cell responses detected in any group. INTERPRETATION: BCG revaccination administered as a single dose ID and both H4:IC31 and H56:IC31 administered as 2 doses IM had acceptable safety profiles in healthy, QFT-negative, previously BCG-vaccinated adolescents. Characterization of the assays and the immunogenicity of these vaccines may help to identify valuable markers of protection for upcoming immune correlates analyses of C-040-404 and future TB vaccine efficacy trials. FUNDING: NIAID and Aeras.

The HyVac4 subunit vaccine efficiently boosts BCG-primed anti-mycobacterial protective immunity.

BACKGROUND: The current vaccine against tuberculosis (TB), BCG, has failed to control TB worldwide and the protective efficacy is moreover limited to 10-15 years. A vaccine that could efficiently boost a BCG-induced immune response and thus prolong protective immunity would therefore have a significant impact on the global TB-burden. METHODS/FINDINGS: In the present study we show that the fusion protein HyVac4 (H4), consisting of the mycobacterial antigens Ag85B and TB10.4, given in the adjuvant IC31® or DDA/MPL effectively boosted and prolonged immunity induced by BCG, leading to improved protection against infection with virulent M. tuberculosis (M.tb). Increased protection correlated with an increased percentage of TB10.4 specific IFNγ/TNFα/IL-2 or TNFα/IL-2 producing CD4 T cells at the site of infection. Moreover, this vaccine strategy did not compromise the use of ESAT-6 as an accurate correlate of disease development/vaccine efficacy. Indeed both CD4 and CD8 ESAT-6 specific T cells showed significant correlation with bacterial levels. CONCLUSIONS/SIGNIFICANCE: H4-IC31® can efficiently boost BCG-primed immunity leading to an increased protective anti-M.tb immune response dominated by IFNγ/TNFα/IL-2 or TNFα/IL2 producing CD4 T cells. H4 in the CD4 T cell inducing adjuvant IC31® is presently in clinical trials.

A New Experimental Infection Model in Ferrets Based on Aerosolised Mycobacterium bovis.

There is significant interest in developing vaccines to control bovine tuberculosis, especially in wildlife species where this disease continues to persist in reservoir species such as the European Badger (Meles meles). However, gaining access to populations of badgers (protected under UK law) is problematic and not always possible. In this study, a new infection model has been developed in ferrets (Mustela furo), a species which is closely related to the badger. Groups of ferrets were infected using a Madison infection chamber and were examined postmortem for the presence of tuberculous lesions and to provide tissue samples for confirmation of Mycobacterium bovis by culture. An infectious dose was defined, that establishes infection within the lungs and associated lymph nodes with subsequent spread to the mesentery lymph nodes. This model, which emphasises respiratory tract infection, will be used to evaluate vaccines for the control of bovine tuberculosis in wildlife species.