Safety and Immunogenicity of the Recombinant BCG Vaccine AERAS-422 in Healthy BCG-naïve Adults: A Randomized, Active-controlled, First-in-human Phase 1 Trial.

BACKGROUND: We report a first-in-human trial evaluating safety and immunogenicity of a recombinant BCG, AERAS-422, over-expressing TB antigens Ag85A, Ag85B, and Rv3407 and expressing mutant perfringolysin. METHODS: This was a randomized, double-blind, dose-escalation trial in HIV-negative, healthy adult, BCG-naïve volunteers, negative for prior exposure to Mtb, at one US clinical site. Volunteers were randomized 2:1 at each dose level to receive a single intradermal dose of AERAS-422 (>10(5)-<10(6)CFU=low dose, ≥10(6)-<10(7)CFU=high dose) or non-recombinant Tice BCG (1-8×10(5)CFU). Randomization used an independently prepared randomly generated sequence of treatment assignments. The primary and secondary outcomes were safety and immunogenicity, respectively, assessed in all participants through 182days post-vaccination. ClinicalTrials.gov registration number: NCT01340820. FINDINGS: Between Nov 2010 and Aug 2011, 24 volunteers were enrolled (AERAS-422 high dose, n=8; AERAS-422 low dose, n=8; Tice BCG, n=8); all were included in the safety and immunogenicity analyses. All 24 subjects had at least one adverse event, primarily expected local reactions. High dose AERAS-422 vaccination induced Ag85A- and Ag85B-specific lymphoproliferative responses and marked anti-mycobacterial activity in a whole blood bactericidal activity culture assay (WBA), but was associated with varicella zoster virus (VZV) reactivation in two vaccinees. These volunteers displayed high BCG-specific IFN-γ responses pre- and post-vaccination possibly predisposing them to autocrine/paracrine negative regulation of immune control of latent VZV. A systems biology transcriptomal approach identified positive correlations between post-vaccination T cell expression modules and WBA, and negative correlations between post-vaccination monocyte expression modules and WBA. The expression of one key macrophage marker (F4/80) was constitutively elevated in the two volunteers with zoster. INTERPRETATION: The unexpected development of VZV in two of eight healthy adult vaccine recipients resulted in discontinuation of AERAS-422 vaccine development. Immunological and transcriptomal data identified correlations with the development of TB immunity and VZV that require further investigation. FUNDING: Aeras, FDA, Bill and Melinda Gates Foundation.

Inhibition of mycobacterial growth in vitro following primary but not secondary vaccination with Mycobacterium bovis BCG.

Despite the widespread use of the Mycobacterium bovis BCG vaccine, there are more than 9 million new cases of tuberculosis (TB) every year, and there is an urgent need for better TB vaccines. TB vaccine candidates are selected for evaluation based in part on the detection of an antigen-specific gamma interferon (IFN-γ) response. The measurement of mycobacterial growth in blood specimens obtained from subjects immunized with investigational TB vaccines may be a better in vitro correlate of in vivo vaccine efficacy. We performed a clinical study with 30 United Kingdom adults who were followed for 6 months to evaluate the abilities of both a whole-blood- and a novel peripheral blood mononuclear cell (PBMC)-based mycobacterial growth inhibition assay to measure a response to primary vaccination and revaccination with BCG. Using cryopreserved PBMCs, we observed a significant improvement in mycobacterial growth inhibition following primary vaccination but no improvement in growth inhibition following revaccination with BCG (P < 0.05). Mycobacterial growth inhibition following primary BCG vaccination was not correlated with purified protein derivative (PPD) antigen-specific IFN-γ enzyme-linked immunospot (ELISPOT) responses. We demonstrate that a mycobacterial growth inhibition assay can detect improved capacity to control growth following primary immunization, but not revaccination, with BCG. This is the first study to demonstrate that an in vitro growth inhibition assay can identify a difference in vaccine responses by comparing both primary and secondary BCG vaccinations, suggesting that in vitro growth inhibition assays may serve as better surrogates of clinical efficacy than the assays currently used for the assessment of candidate TB vaccines.

Preventive vaccines for tuberculosis.

There are nearly ten million new cases and 1.4 million deaths from tuberculosis (TB) each year, and the 90-year old bacille calmette-guérin (BCG) vaccine in widespread use appears to have minimal impact on the worldwide incidence, despite demonstrating reasonable efficacy against complications of infant TB and death. Novel vaccine development has accelerated in the past ten years, with at least 16 candidates entering human trials, and a few vaccines have entered into Phase 2b efficacy studies. However, different vaccines may be needed due to the varying disease states (naïve, latently infected, or active), the ages affected (infants, adolescents and young adults, the elderly), and patient health status (HIV and immunocompromised patients especially). Modeling has shown that mass vaccination of latently infected populations, especially adolescents and young adults, will likely have the largest impact on new infection rates. At present, research and development of TB vaccines is hampered by the lack of validated animal models, the absence of correlates of immunity and a human challenge model, as well as by the size and cost of Proof-of-Concept clinical trials. Nonetheless, ongoing research and clinical studies should remove many of these barriers over the next five years, and lead to an increased understanding of the pathogenicity of Mycobacterium tuberculosis and what may constitute protective immunity during various stages of infection and disease.

Rational approach to selection and clinical development of TB vaccine candidates.

A rational process is clearly needed and can be extremely helpful for selection, assessing and advancing TB vaccine candidates from entry into preclinical and clinical development and for advancing candidates from early safety and immunogenicity clinical trials to proof-of-concept and pivotal efficacy trials. A joint effort between Aeras and the Tuberculosis Vaccine Initiative has focused on the development of objective criteria for a number of key general vaccine characteristics which can be assessed at critical stages of development. In order to maximize development efficiency, increase likelihood of success, and optimize use of scarce resources, this process includes establishment of gates for moving TB vaccine candidates through progressive development stages based on meeting the established criteria for specific vaccine candidates.

Efficacy of percutaneous versus intradermal BCG in the prevention of tuberculosis in South African infants: randomised trial.

OBJECTIVE: To compare the incidence of tuberculosis over two years in infants vaccinated at birth with intradermal BCG or with percutaneous BCG. DESIGN: Randomised trial. SETTING: South Africa. PARTICIPANTS: 11,680 newborn infants. INTERVENTIONS: Infants were randomised by week of birth to receive Tokyo 172 BCG vaccine through the percutaneous route (n=5775) or intradermal route (n=5905) within 24 hours of birth and followed up for two years. MAIN OUTCOME MEASURES: The primary outcome measure was documented Mycobacterium tuberculosis infection or radiological and clinical evidence of tuberculosis disease. Secondary outcome measures were rates of adverse events, all cause and tuberculosis specific admissions to hospital, and mortality. RESULTS: The difference in the cumulative incidence of definite, probable, and possible tuberculosis between the intradermal group and the percutaneous group, as defined using study definitions based on microbiological, radiological, and clinical findings was -0.36% (95.5% confidence interval -1.27% to 0.54%). No significant differences were found between the routes in the cumulative incidence of tuberculosis using a range of equivalence of "within 25%." Additionally, no significant differences were found between the routes in the cumulative incidence of adverse events (risk ratio 0.98, 95% confidence interval 0.91 to 1.06), including deaths (1.19, 0.89 to 1.58). CONCLUSION: Equivalence was found between intradermal BCG vaccine and percutaneous BCG in the incidence of tuberculosis in South African infants vaccinated at birth and followed up for two years. The World Health Organization should consider revising its policy of preferential intradermal vaccination to allow national immunisation programmes to choose percutaneous vaccination if that is more practical. Trial registration ClinicalTrials.gov NCT00242047.

Controlled trials of very high dose folic acid, vitamins B12 and B6, intravenous folinic acid and serine for treatment of hyperhomocysteinemia in ESRD.

BACKGROUND: Hyperhomocysteinemia is seen in most hemodialysis (HD) patients and is an independent risk factor for cardiovascular disease. Homocysteine metabolism via remethylation requires activated folate and vitamin B12 and metabolism via transsulfuration requires serine and vitamin B6. Prior studies have shown highly variable effects of supplemental B vitamin and folate therapy for hyperhomocysteinemia. We undertook a fully controlled trial with abnormally high doses of folic acid alone or with supplemental vitamin B6 and B12 compared with active folate alone or with serine. METHODS: Two prospective studies were undertaken in hemodialysis patients. In the first study (protocol A), hyperhomocysteinemia was treated in 77 patients with 30 or 60 mg folic acid with or without vitamins B6 and B12 for eight weeks and compared with matching placebos. In the second study (protocol B), hyperhomocysteinemia was treated in 37 patients with intravenous folinic acid given alone or with serine and compared with matching placebos. All patients received the standard of care treatment with a multivitamin tablet before and throughout the protocol to test the hypothesis that additional therapy is required over and above the routine therapy for maximum reduction in total homocysteine (tHcy). RESULTS: Normal volunteers; The mean (SD) tHcy of 128 normal subjects was 6.5 (4) micromol/L. Protocol A; Plasma folate increased significantly in the groups given folic acid at both four and eight weeks (P = 0.0001 at both time points). Plasma vitamin B12 was significantly increased at four weeks (P = 0.0018) but not at eight weeks (P = 0.064) in those given Vitamin B12. However, tHcy did not differ between treatment groups at baseline (P = 0.63), four weeks (P = 0.79) or eight weeks (P = 0.74). Protocol B: Plasma folate increased significantly at four weeks in those receiving folinic acid (P = 0.0001) but tHcy was not significantly different between groups (P = 0.92). In neither study was there any significant change in tHcy comparing before and during any treatment intervention. CONCLUSIONS: In our studies high dose oral folic acid, intravenous folinic acid, vitamins B6 and B12 and oral serine were ineffective at lowering tHcy in patients on hemodialysis when given folic acid, folinic acid serine or B vitamins in addition to routine folic acid and B vitamin supplements.