Safety of a controlled human infection model of tuberculosis with aerosolised, live-attenuated Mycobacterium bovis BCG versus intradermal BCG in BCG-naive adults in the UK: a dose-escalation, randomised, controlled, phase 1 trial

BACKGROUND

Mycobacterium tuberculosis is the main causative agent of tuberculosis. BCG, the only licensed vaccine, provides inadequate protection against pulmonary tuberculosis. Controlled human infection models are useful tools for vaccine development. We aimed to determine a safe dose of aerosol-inhaled live-attenuated Mycobacterium bovis BCG as a surrogate for M tuberculosis infection, then compare the safety and tolerability of infection models established using aerosol-inhaled and intradermally administered BCG.

METHODS

This phase 1 controlled human infection trial was conducted at two clinical research facilities in the UK. Healthy, immunocompetent adults aged 18-50 years, who were both M tuberculosis-naive and BCG-naive and had no history of asthma or other respiratory diseases, were eligible for the trial. Participants were initially enrolled into group 1 (receiving the BCG Danish strain); the trial was subsequently paused because of a worldwide shortage of BCG Danish and, after protocol amendment, was restarted using the BCG Bulgaria strain (group 2). After a dose-escalation study, during which participants were sequentially allocated to receive either 1 × 103, 1 × 104, 1 × 105, 1 × 106, or 1 × 107 colony-forming units (CFU) of aerosol BCG, the maximum tolerated dose was selected for the randomised controlled trial. Participants in this trial were randomly assigned (9:12), by variable block randomisation and using sequentially numbered sealed envelopes, to receive aerosol BCG (1 × 107 CFU) and intradermal saline or intradermal BCG (1 × 106 CFU) and aerosol saline. Participants were masked to treatment allocation until day 14. The primary outcome was to compare the safety of a controlled human infection model based on aerosol-inhaled BCG versus one based on intradermally administered BCG, and the secondary outcome was to evaluate BCG recovery in the airways of participants who received aerosol BCG or skin biopsies of participants who received intradermal BCG. BCG was detected by culture and by PCR. The trial is registered at ClinicalTrials.gov, NCT02709278, and is complete.

FINDINGS

Participants were assessed for eligibility between April 7, 2016, and Sept 29, 2018. For group 1, 15 participants were screened, of whom 13 were enrolled and ten completed the study; for group 2, 60 were screened and 33 enrolled, all of whom completed the study. Doses up to 1 × 107 CFU aerosol-inhaled BCG were sufficiently well tolerated. No significant difference was observed in the frequency of adverse events between aerosol and intradermal groups (median percentage of solicited adverse events per participant, post-aerosol vs post-intradermal BCG: systemic 7% [IQR 2-11] vs 4% [1-13], p=0·62; respiratory 7% [1-19] vs 4% [1-9], p=0·56). More severe systemic adverse events occurred in the 2 weeks after aerosol BCG (15 [12%] of 122 reported systemic adverse events) than after intradermal BCG (one [1%] of 94; difference 11% [95% CI 5-17]; p=0·0013), but no difference was observed in the severity of respiratory adverse events (two [1%] of 144 vs zero [0%] of 97; 1% [-1 to 3]; p=0·52). All adverse events after aerosol BCG resolved spontaneously. One serious adverse event was reported-a participant in group 2 was admitted to hospital to receive analgesia for a pre-existing ovarian cyst, which was deemed unrelated to BCG infection. On day 14, BCG was cultured from bronchoalveolar lavage samples after aerosol infection and from skin biopsy samples after intradermal infection.

INTERPRETATION

This first-in-human aerosol BCG controlled human infection model was sufficiently well tolerated. Further work will evaluate the utility of this model in assessing vaccine efficacy and identifying potential correlates of protection.

FUNDING

Bill & Melinda Gates Foundation, Wellcome Trust, National Institute for Health Research Oxford Biomedical Research Centre, Thames Valley Clinical Research Network, and TBVAC2020.

Complex Endovascular Repair of Paravisceral Infective Native Aortic Aneurysms

OBJECTIVE

To report the early and mid-term outcome of complex endovascular repair (EVAR) for paravisceral infective native aortic aneurysms (INAA).

METHODS

Interrogation of a prospectively maintained database identified consecutive patients who underwent non-elective complex EVAR for paravisceral INAAs in a single institution between December 2013 and June 2020. All patients were considered to have definite INAAs based on diagnostic criteria. Patients who had prior aortic repair were excluded.

RESULTS

A total of 26 patients (19 men; mean age 67 years [SD = 11.4]; median diameter 60 mm [IQR: 55-73]) with acute symptomatic (n = 24) or contained ruptured (n = 2) aneurysms underwent surgeon-modified fenestrated EVAR (SM-FEVAR; n = 24) or chimney-periscope EVAR (CHIMPS; n = 2). Median observed follow-up was 36.2 months (18.3-53.5). Nine patients had positive venous blood cultures and a further seven had recent or concomitant infection. All patients received pre- and post-operative antibiotic therapy and rifampicin-soaked endografts. A total of 95 vessels were targeted for preservation and 86 were stent-grafted. One vessel occluded intra-operatively and a further 3 occluded within 30 days. The 30-day/in-hospital mortality was 11.5% (n = 3), and the estimated 1- and 3-year survival (±SD) was 85% ± 7%. Infection-related complications (IRCs) occurred in two patients: both developed new INAA within 30 days of index repair and were treated by EVAR with no mortality. Estimated 3-year freedom from late re-intervention was 100%. One patient required infrarenal EVAR for a non-infective aneurysm at 43 months.

CONCLUSION

Complex EVAR for paravisceral INAAs is associated with acceptable early and mid-term outcomes and is an acceptable alternative to open surgery. We propose that these patients are managed with long-term antimicrobials, impregnation of graft material with rifampicin, and rigorous post-operative surveillance.

CLINICAL IMPACT

A multi-disciplinary approach is required to deliver the best possible outcome for patients with this challenging aortic pathology.

P13 Development of a consult and antimicrobial stewardship service in Manchester Foundation Trust

Objectives

To prospectively audit the first year of the North Manchester infectious diseases AMS and Consult service June 2020 to June 2021 to: (i) characterize the number of patients who had antibiotic treatment narrowed, duration reduced and/or switch to oral options; (ii) assess documentation of indication and duration of antibiotic prescriptions; (iii) determine whether or not the appropriate microbiological specimens have been performed and with the lab; (iv) identify the impact on antibiotic consumption measured in defined daily dose (DDDs); and (v) establish whether base teams act on the advice given by the Consult/AMS team (data over a 6 week period).

Methods

On weekdays an electronic prescribing list of all patients prescribed piperacillin/tazobactam, meropenem and ciprofloxacin was generated, and the consults team performed either a bedside or notes review. Data was collected prospectively on 730 patients on which infection was treated, which specialty managed the patient, microbiology samples sent, duration and indication of treatment documentation, and advice given by consults team. Data was then collected over a further 6 weeks looking at whether the base specialty carried out the advice of the AMS team.

Results

The main indication for broad spectrum antibiotic use was urinary tract infection (151/720) and hospital acquired pneumonia (104/720). Poor documentation of antimicrobial indication and duration was observed across all specialties (277/720). Just over 50% of appropriate microbiology samples were sent (422/726). For 42% of cases (311/730), colleagues were advised to stop or reduce antibiotic duration. In 30% of cases (220/730), narrowing of antibiotic spectrum was advised. Thirty percent (219/730) were advised on IV to oral switch. There was a modest reduction in antimicrobial consumption in some specialties comparing the year prior to the introduction of the service 2019–20 to 2020–21; 17.4% reduction respiratory (7810/9137), 0.2% increase in medicine (272698/267351) and 2.1% surgery (68722/67309). In 81 patients reviewed to look at outcomes over 6 weeks, 88% of Consult/AMS team advice was actioned by the lead specialties involved in the patients’ care.

Conclusions

(i) There is a substantial need for an AMS service within the hospital. (ii) Outcome data shows the ward teams engage with the service and most follow advice. (iii) The service contributed to limiting inappropriate prescribing during the COVID-19 pandemic. There was a modest rise in hospital-wide consumption. (iv) The AMS service needs to be available to provide patient equity across Manchester Foundation Trust, fostering a city-wide AMS strategy that encompasses education, guidelines, audit and quality improvement.

A phase I trial evaluating the safety and immunogenicity of a candidate tuberculosis vaccination regimen, ChAdOx1 85A prime - MVA85A boost in healthy UK adults

Background

This phase I trial evaluated the safety and immunogenicity of a candidate tuberculosis vaccination regimen, ChAdOx1 85A prime-MVA85A boost, previously demonstrated to be protective in animal studies, in healthy UK adults.

Methods

We enrolled 42 healthy, BCG-vaccinated adults into 4 groups: low dose Starter Group (n = 6; ChAdOx1 85A alone), high dose groups; Group A (n = 12; ChAdOx1 85A), Group B (n = 12; ChAdOx1 85A prime – MVA85A boost) or Group C (n = 12; ChAdOx1 85A – ChAdOx1 85A prime – MVA85A boost). Safety was determined by collection of solicited and unsolicited vaccine-related adverse events (AEs). Immunogenicity was measured by antigen-specific ex-vivo IFN-γ ELISpot, IgG serum ELISA, and antigen-specific intracellular IFN-γ, TNF-α, IL-2 and IL-17.

Results

AEs were mostly mild/moderate, with no Serious Adverse Events. ChAdOx1 85A induced Ag85A-specific ELISpot and intracellular cytokine CD4+ and CD8+ T cell responses, which were not boosted by a second dose, but were boosted with MVA85A. Polyfunctional CD4+ T cells (IFN-γ, TNF-α and IL-2) and IFN-γ+, TNF-α+ CD8+ T cells were induced by ChAdOx1 85A and boosted by MVA85A. ChAdOx1 85A induced serum Ag85A IgG responses which were boosted by MVA85A.

Conclusion

A ChAdOx1 85A prime – MVA85A boost is well tolerated and immunogenic in healthy UK adults.

Brain tumour? - Cerebellar histoplasmosis as a solitary mass lesion

A 50-year-old man who had been living in Thailand presented with a history of falls, deteriorating vision and weight loss over several months. He had been admitted to a hospital in Thailand where he was given a diagnosis of multiple sclerosis. Neurological examination revealed a mild ataxic gait and lateral nystagmus, but no other abnormalities. He tested positive for human immunodeficiency virus with a CD4 cell count of 16 cells/µL. Brain magnetic resonance imaging was suggestive of an intrinsic neoplasm and he underwent stereotactic brain biopsy which showed numerous yeast-like organisms. Panfungal polymerase chain reaction was positive for Histoplasma capsulatum. He received liposomal amphotericin B for six weeks, followed by itraconazole, and started antiretroviral therapy four weeks into treatment. He developed an immune reconstitution inflammatory syndrome which responded well to steroids. Six months after diagnosis, he has no neurological symptoms or signs and remains on itraconazole. Isolated bulky central nervous system histoplasmomas are exceedingly rare. A clinical suspicion of immunosuppression was key in making this diagnosis.

Alternate aerosol and systemic immunisation with a recombinant viral vector for tuberculosis, MVA85A: A phase I randomised controlled trial

BACKGROUND

There is an urgent need for an effective tuberculosis (TB) vaccine. Heterologous prime-boost regimens induce potent cellular immunity. MVA85A is a candidate TB vaccine. This phase I clinical trial was designed to evaluate whether alternating aerosol and intradermal vaccination routes would boost cellular immunity to the Mycobacterium tuberculosis antigen 85A (Ag85A).

METHODS AND FINDINGS

Between December 2013 and January 2016, 36 bacille Calmette-Guérin-vaccinated, healthy UK adults were randomised equally between 3 groups to receive 2 MVA85A vaccinations 1 month apart using either heterologous (Group 1, aerosol-intradermal; Group 2, intradermal-aerosol) or homologous (Group 3, intradermal-intradermal) immunisation. Bronchoscopy and bronchoalveolar lavage (BAL) were performed 7 days post-vaccination. Adverse events (AEs) and peripheral blood were collected for 6 months post-vaccination. The laboratory and bronchoscopy teams were blinded to treatment allocation. One participant was withdrawn and was replaced. Participants were aged 21-42 years, and 28/37 were female. In a per protocol analysis, aerosol delivery of MVA85A as a priming immunisation was well tolerated and highly immunogenic. Most AEs were mild local injection site reactions following intradermal vaccination. Transient systemic AEs occurred following vaccination by both routes and were most frequently mild. All respiratory AEs following primary aerosol MVA85A (Group 1) were mild. Boosting an intradermal MVA85A prime with an aerosolised MVA85A boost 1 month later (Group 2) resulted in transient moderate/severe respiratory and systemic AEs. There were no serious adverse events and no bronchoscopy-related complications. Only the intradermal-aerosol vaccination regimen (Group 2) resulted in modest, significant boosting of the cell-mediated immune response to Ag85A (p = 0.027; 95% CI: 28 to 630 spot forming cells per 1 × 106 peripheral blood mononuclear cells). All 3 regimens induced systemic cellular immune responses to the modified vaccinia virus Ankara (MVA) vector. Serum antibodies to Ag85A and MVA were only induced after intradermal vaccination. Aerosolised MVA85A induced significantly higher levels of Ag85A lung mucosal CD4+ and CD8+ T cell cytokines compared to intradermal vaccination. Boosting with aerosol-inhaled MVA85A enhanced the intradermal primed responses in Group 2. The magnitude of BAL MVA-specific CD4+ T cell responses was lower than the Ag85A-specific responses. A limitation of the study is that while the intradermal-aerosol regimen induced the most potent cellular Ag85A immune responses, we did not boost the last 3 participants in this group because of the AE profile. Timing of bronchoscopies aimed to capture peak mucosal response; however, peak responses may have occurred outside of this time frame.

CONCLUSIONS

To our knowledge, this is the first human randomised clinical trial to explore heterologous prime-boost regimes using aerosol and systemic routes of administration of a virally vectored vaccine. In this trial, the aerosol prime-intradermal boost regime was well tolerated, but intradermal prime-aerosol boost resulted in transient but significant respiratory AEs. Aerosol vaccination induced potent cellular Ag85A-specific mucosal and systemic immune responses. Whilst the implications of inducing potent mucosal and systemic immunity for protection are unclear, these findings are of relevance for the development of aerosolised vaccines for TB and other respiratory and mucosal pathogens.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01954563.