Based on current data rBCG vaccines to replace BCG priming at birth should be compared to data on the efficacy of BCG against pulmonary TB: 70% at 10 years, and 50% at 20 years. Since long term ...trials for comparison would be a challenging to conduct, trials of rBCG should include a control arm with current BCG. Modelling indicates that development of an effective BCG booster will have a greater and more immediate effect on global tuberculosis than an improved BCG for priming infants 9. ...both standard BCG and rBCG are also being considered as boosters for adolescents or adults primed with BCG at birth. Both intradermal injection and bladder instillation of live BCG can be associated with bacteremia leading to early or late disseminated vaccine strain infection. Since both local and systemic side effects are immune-mediated, and because rBCG vaccines have been developed to increase immunogenicity, careful surveillance for side effects will be essential.
Highlights • New vaccines for tuberculosis are urgently needed to control this devastating disease. • Several novel vaccine candidates have entered clinical trials. • Candidates comprise subunit ...vaccines and whole-cell vaccines. • Candidates target mostly prevention of disease; some also target prevention of infection. • Some candidates target unexposed individuals, and others target exposed individuals.
SRL172 prevented disease due to Mycobacterium tuberculosis in a Phase 3 trial. DAR-901 represents a scalable manufacturing process for SRL172. We sought to determine if DAR-901 would prevent ...infection with M. tuberculosis among BCG-primed adolescents age 13–15 years in Tanzania.
Adolescents with a negative T- SPOT.TBR interferon gamma release assay (IGRA) were randomized 1:1 to three intradermal injections of DAR-901 or saline placebo at 0, 2 and 4 months. Repeat IGRAs were performed at 2 months, and at 1, 2, and 3 years. The primary efficacy outcome was time to new TB infection (IGRA conversion to positive); the secondary outcome was time to persistent TB infection (IGRA conversion with repeat positive IGRA).
Among 936 participants screened 667 were eligible and randomized to their first dose of vaccine or placebo (safety cohort). At 2 months, 625 participants remained IGRA-negative and were scheduled for the additional two doses (efficacy cohort). DAR-901 was safe and well-tolerated. One DAR-901 recipient developed a vaccine site abscess. Neither the primary nor secondary endpoints differed between the two treatment arms (p = 0.90 and p = 0.20, respectively). DAR-901 IGRA converters had median responses to ESAT-6 of 50.1 spot-forming cells (SFCs) vs. 19.6 SFCs in placebo IGRA converters (p = 0.03).
A three-dose series of 1 mg DAR-901 was safe and well-tolerated but did not prevent initial or persistent IGRA conversion. DAR-901 recipients with IGRA conversion demonstrated enhanced immune responses to ESAT-6. Since protection against disease may require different immunologic responses than protection against infection a trial of DAR-901 to prevent TB disease is warranted.
Trial Registration. The trial is registered at ClinicalTrials.gov as NCT02712424.
The current vaccine against tuberculosis, BCG, is effective when given in most TB-endemic countries at birth but has diminished efficacy against pulmonary TB after 15-20 years. As a result, new ...booster vaccines for adolescents and adults are being developed to realize the World Health Organization target of global elimination of TB by 2035. Multiple TB candidates thus are in active clinical development.
One of these, DAR-901, is advancing in human clinical trials. These clinical trials are conducted in BCG immunized adults with and without HIV infection in order to assess safety and efficacy among the people most in need of a new vaccine. A Phase I dose escalation trial of DAR-901 in BCG-immunized adults with or without HIV infection was conducted between 2014 and 2016. This offered an unusual opportunity to qualitatively examine why foreign-born adults living in the United States - a poorly studied population - decide to participate, or not, in clinical trials.
We conducted a qualitative study of individuals who were recruited to participate in this Phase I vaccine trial, interviewing those who agreed and declined to participate. We found diverse motivations for participation or refusal; varied understandings of tuberculosis and vaccines; and complex views about how 'informed consent' can be at odds with cultural understandings of power, authority, and medical decision-making. These dynamics included: knowledge (direct or indirect) of tuberculosis, a desire to be altruistic and simultaneous hopes for personal gain as well as concerns over what remuneration for participation could mean, the importance of personal relationships with care providers in shaping volunteerism, concerns over privacy, and evidence of how culture and history shape medical decision-making.
This US-based trial, aimed at addressing a crucible global health issue, raises productive questions about the interface between altruism and scepticism regarding clinical research participation.
NCT02063555 .
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
T-SPOT.TB assays were performed manually on healthy adolescents during a tuberculosis vaccine trial in Tanzania at 5 intervals over 3 years. Assay results were defined as negative, positive, ...borderline or invalid. Subsequently, microtiter plates were analyzed by an automated reader to obtain quantitative counts of spot forming cells (SFCs) for the present analysis. 3387 T-SPOT.TB samples were analyzed from 928 adolescents; manual and automated assay results were 97% concordant. Based on the quantitative results 143 (15%) participants were prevalent IGRA-positives at baseline, were ineligible for further study. Among the remaining IGRA-negative participants, the annual rate of IGRA conversion was 2·9%. Among 43 IGRA converters with repeat assays 12 (28%) were persistent converters, 16 (37%) were transient converters, and 15 (35%) comprised a new category defined as irregular converters (greater than or equal to2 different subsequent results). ESAT-6 and CFP-10 responses were higher in prevalent than incident positives: 53 vs 36 for CFP-10 (p < 0·007); 44 vs 34 for ESAT-6 (p = 0·12). Definitions of IGRA conversion, reversion, and persistence depend critically on the frequency of testing. Multiple shifts in categories among adolescents in a TB-endemic country may represent multiple infections, variable host responses in subclinical infection, or assay variation. These findings should to be considered in the design and interpretation of TB vaccine trials based on prevention of infection. Household contact studies could determine whether even transient IGRA conversion might represent exposure to an active case of M. tuberculosis disease.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
•Numerous well-designed and rigorous prospective trials demonstrate that childhood BCG immunization provides protection against pulmonary tuberculosis.•Recent national retrospective reviews confirm ...the efficacy of BCG against pulmonary TB.•The efficacy of BCG against pulmonary TB remains high for at least 15–20 years and is substantial for as long as 50 years.•Accurate, contemporary understanding of the efficacy of BCG against pulmonary tuberculosis is critical to the development and evaluation of investigational vaccines intended to replace or boost BCG.
The efficacy of childhood BCG vaccination in the prevention of adult pulmonary tuberculosis is not universally accepted.
We reviewed the published literature and summarized studies of BCG vaccination reporting long-term protection against pulmonary TB.
We identified 15 papers reporting prospective studies and their long-term follow up, retrospective studies or systematic reviews.
Good quality evidence supports the efficacy of BCG vaccination in the prevention of adult pulmonary tuberculosis.
Peripheral tuberculous lymphadenitis accounts for ∼10% of tuberculosis cases in the United States. Epidemiologic characteristics include a 1.4:1 female-to-male ratio, a peak age range of 30—40 years, ...and dominant foreign birth, especially East Asian. Patients present with a 1—2 month history of painless swelling of a single group of cervical lymph nodes. Definitive diagnosis is by culture or nucleic amplification of Mycobacterium tuberculosis; demonstration of acid fast bacilli and granulomatous inflammation may be helpful. Excisional biopsy has the highest sensitivity at 80%, but fine-needle aspiration is less invasive and may be useful, especially in immunocompromised hosts and in resource-limited settings. Antimycobacterial therapy remains the cornerstone of treatment, but response is slower than with pulmonary tuberculosis; persistent pain and swelling are common, and paradoxical upgrading reactions may occur in 20% of patients. The role of steroids is controversial. Initial excisional biopsy deserves consideration for both optimal diagnosis and management of the otherwise slow response to therapy.
Development of a tuberculosis vaccine to boost BCG is a major international health priority. SRL172, an inactivated whole cell booster derived from a non-tuberculous mycobacterium, is the only new ...vaccine against tuberculosis to have demonstrated efficacy in a Phase 3 trial. In the present study we sought to determine if a three-dose series of DAR-901 manufactured from the SRL172 master cell bank by a new, scalable method was safe and immunogenic.
We performed a single site, randomized, double-blind, controlled, Phase 1 dose escalation trial of DAR-901 at Dartmouth-Hitchcock Medical Center in the United States. Healthy adult subjects age 18-65 with prior BCG immunization and a negative interferon-gamma release assay (IGRA) were enrolled in cohorts of 16 subjects and randomized to three injections of DAR-901 (n = 10 per cohort), or saline placebo (n = 3 per cohort), or two injections of saline followed by an injection of BCG (n = 3 per cohort; 1-8 x 106 CFU). Three successive cohorts were enrolled representing DAR-901 at 0.1, 0.3, and 1 mg per dose. Randomization was performed centrally and treatments were masked from staff and volunteers. Subsequent open label cohorts of HIV-negative/IGRA-positive subjects (n = 5) and HIV-positive subjects (n = 6) received three doses of 1 mg DAR-901. All subjects received three immunizations at 0, 2 and 4 months administered as 0.1 mL injections over the deltoid muscle alternating between right and left arms. The primary outcomes were safety and immunogenicity. Subjects were followed for 6 months after dose 3 for safety and had phlebotomy performed for safety studies and immune assays before and after each injection. Immune assays using peripheral blood mononuclear cells included cell-mediated IFN-γ responses to DAR-901 lysate and to Mycobacterium tuberculosis (MTB) lysate; serum antibody to M. tuberculosis lipoarabinomannan was assayed by ELISA.
DAR-901 had an acceptable safety profile and was well-tolerated at all dose levels in all treated subjects. No serious adverse events were reported. Median (range) 7-day erythema and induration at the injection site for 1 mg DAR-901 were 10 (4-20) mm and 10 (4-16) mm, respectively, and for BCG, 30 (10-107) mm and 38 (15-55) mm, respectively. Three mild AEs, all headaches, were considered possibly related to DAR-901. No laboratory or vital signs abnormalities were related to immunization. Compared to pre-vaccination responses, three 1 mg doses of DAR-901 induced statistically significant increases in IFN-γ response to DAR-901 lysate and MTB lysate, and in antibody responses to M. tuberculosis lipoarabinomannan. Ten subjects who received 1 mg DAR-901 remained IFN-γ release assay (IGRA) negative after three doses of vaccine.
A three-injection series of DAR-901 was well-tolerated, had an acceptable safety profile, and induced cellular and humoral immune responses to mycobacterial antigens. DAR-901 is advancing to efficacy trials.
ClinicalTrials.gov NCT02063555.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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