Helen Fletcher, PhD Senior Lecturer in Immunology, London School of Hygiene and Tropical Medicine

1. The MVA85A Phase IIb study in South African infants- what can we learn from this TB vaccine efficacy trial? Helen Fletcher, PhD Senior Lecturer in Immunology, London School of Hygiene and Tropical Medicine

2. Why is TB vaccine development so difficult? Rappuloi and Aderem, Nature 2012

3. TB vaccines - BCG • Live attenuated M.bovis • First given in 1921 • Administered at birth in endemic countries • 0-80% efficacy • Reasons for variability? • Variations in BCG strain • Geographical location and exposure to environmental non-tuberculousmycobacteria • Nutrition • BUT protects against disseminated TB, TB meningitis in children, and leprosy • Safety issues in immunosuppressed individuals

4. Modified vaccinia Ankara (MVA) Poxvirus No replication in mammalian tissues Good T cell boosting vector Excellent safety record M.tb antigen 85A Mycolyl transferase Major target antigen Protective in small animals In all environmental mycobacteria Doesn’t interfere with new diagnostic tests MVA85A

5. BCG Prime – MVA85A Boost Vaccines encoding the same antigen, are given several weeks apart boost BCG prime T cell response Time Highly effective at inducing high levels of antigen specific T cells

6. Immune responses in UK Adults UK high dose (1 x 108 pfu)

7. MVA85A can improve BCG induced protection in preclinical animal models MICE NHP Goonetilleke et al, JI 2003 Verreck et al, PLoS ONE 2009 GUINEA PIGS CATTLE Williams et al, I&I 2005 Vordermeier M et al, I&I 2009

8. www.thelancet.com Published online February 4, 2013 http://dx.doi.org/10.1016/S0140-6736(13)60177-4 • The first efficacy trial with a new TB vaccine in infants since BCG • BCG last tested in infants in 1968 • The first efficacy trial of a subunit TB vaccine

9. Trial design • Infants randomised to MVA85A (1 x 108pfu) or placebo (candin) • All infants followed up 3 monthly after enrolment until study completed • Any child with TB exposure/symptoms admitted to CV ward for investigation • 507 (36%) of BCG-MVA85A group • 510 (37%) of BCG alone group • Trial powered on TB disease to see 60% improvement over BCG alone (with 90% power) • Follow up extended to reach target endpoint accrual • M.tb infection endpoint using QFT conversion

10. Reasons for screening failure in TB20 Trial • Changed protocol to recruit from home rather than at clinic • Trained phlebotomy staff • Recruited more nurses and field workers

12. During trial we expected to see 300 SAEs 60 deaths TB020 – SAE’s (Serious adverse events) • We saw • 618 SAEs and 417 (64%) were lower respiratory tract infection or gastroenteritis • 37 deaths • 25 deaths were prior to vaccination • 7 in the MVA85A group (2 x kwashiorkor, 2 x meningitis, 1 gastroenteritis, 1 drowning, 1 sudden death) • 4 in the placebo group (2 x gastroenteritis, 1 x lower respiratory tract infection, 1 x encephali)

13. Efficacy

14. TB Endpoint Definition • Isolation of M tuberculosis from any site • Identification of M tuberculosis by an approved molecular diagnostic test One of each of the following: Evidence of mycobacterial infection AND radiographic findings compatible with tuberculosis AND clinical manifestations compatible with tuberculosis

15. MVA85A vaccine efficacy Tameris et al 2013

16. Immunogenicity

17. Ag85A-specific T cell responses: IFN-gELISpot, 7 days post-vaccination Median 136 spm Tameris M et al, Lancet 2013

18. Ag85A-specific T cell responses: Whole blood ICS, 28 days post-vaccination Tameris M et al, Lancet 2013

19. Discussion • Immunogenicity ‘modest’ • Significantly lower (up to 10 fold) than in UK adults • Immature immune system? • Immune response not sufficient to boost efficacy? • Need more or something different?

20. Impact of length of follow up • All follow up (median 24.6 months, IQR 19.2-28.1) • VE 17.3% (CI -31.9 to 48.2) • Follow up truncated at 24 months • VE 23.9% (CI -27.9 to 54.7) • Follow up truncated at 12 months • VE 37.7% (CI -37.2 to 72.8) • No significant efficacy at any time point • Not possible to detect early effect with current design of efficacy trials Tameris M et al, Lancet 2013

21. Assays for immune correlates of risk analysis • Transcriptional analysis • Illumina HT12 arrays • RNA Seq • Fluidigm/qPCR for biomarkers identified in BCG infant study* • Functional Assays • Growth inhibition assays with BCG and MTB • Immune Assays • IFN-γ ELISPOT assays (UNS, PHA, BCG, 85A) • Antibodies on serum samples • Luminex on supernatants from above assays* • Cellular phenotyping • Cell surface flow cytometry for lymphoid and myeloid cells • Markers of acitvation, exhaustion, T cell regulation* • ICS flow cytometry for IFN-g, TNFα, IL2, IL17* • *Secondary assays to be performed on stored supernatant

22. Mycobacterial growth inhibition assays BCG Pasteur WB/PBMC/Splenocytes CFU counts • Measures the summative ability to control mycobacterial growth • No knowledge of underlying immune mechanism required

23. Cases and controls from MVA85A efficacy trial Blinded samples MVA85A vaccinated cases and controls and placebo cases and controls Mycobacterial growth correlates with flow HLA-DR+CD14+CD16- classical monocytes (Day -7)

24. IFN-γ ELISPOT Responses (n=189-289)

25. Summary • No efficacy with MVA85A • Stronger immune responses needed or different type? • Immune correlates of risk analysis should provide some further insight

26. MVA85A Acknowledgements Oxford Emergent Tuberculosis Consortium Jacqui Shea Steve Lockhart Michele Tameris Mark Hatherill Tom Scriba Greg Hussey Hassan Mahomed Willem Hanekom Helen McShane Bernard Landry Peggy Snowden Bruce McClain Tom Evans MVA85A Study team All the mothers and babies