Current status of Mosquirix (RTS,SA), Extended Phase 3 Clinical trials.

1. Malaria Vaccine:
Current Status
Presenter: Dr Pranav Sopory
Department of Pharmacology
All India Institute of Medical Sciences
New Delhi
Mob: 9999-491-690
email: pranav.sopory@gmail.com

2. Contents
1 Burden of Malaria
2 Need of Malaria Vaccine
3 Life Cycle of Plasmodium
4 Types of Malaria
5 Principle Targets of Malaria Vaccine
6 Vaccine currently available
7 Challenges in making an Anti-Malarial Vaccine
8 Newer formulations and their status
9 Ethical Issues

3. Burden of Malaria
• Worldwide Parameters
Maximum risk in Africa:
• -90% of all malaria deaths.
• -68% of deaths occur in children under 5 years of age.
Population at risk 3.2 billion
New cases in 2015 214 million
Deaths 438,000
Case Fatality Rate 0.2%

4. Malaria in India
Population at risk of Transmission
(using Parasite Prevalence)
2014 %
High transmission (> 1 case per 1000 population) 27,55,00,000 22
Low transmission (0–1 cases per 1000 population) 83,89,00,000 67
Malaria-free (0 cases) 13,77,00,000 11
Total 1 25,21,00,000 100
Major Vectors Causes
An. Culicifacies (Rural Malaria)
An. Stephensi (Urban Malaria)
Confirmed cases (2015) 11,26,661
Reported Deaths (2015) 287
Case Fatality rate (2014) 0.2 %

5. Need of a Malaria Vaccine :
Drug resistance
• Vaccines are the most cost-effective component of public health services.
Drug Mechanism of Action Cause of resistance
Chloroquine Inhibits haem (by-product of
Hb metabolism)
polymerization
Drug Efflux via PFCRT
(Plasmodium Falciparum
Chloroquine-Resistance Transporter)
Sulfadoxine(S) +
Pyrimethamine(P)
(Antifolates)
Enzyme Inhibition:
-DHPS(S)
-DHFR(P
Specific gene mutations
encoding for resistance to
both DHPS(S) and DHFR(P)
Atovaquone Inhibition of ETC at the
Cytochrome complex
Single-point mutations in
the cytochrome-b gene
Artemisinin Kill parasites by activation of
free radicals.
Mutations in a gene
encoded on P. falciparum
chromosome 13
Primaquine Generates free radicals
or inhibits ETC.
Unknown

6. Life Cycle of Plasmodium
PE
BS
TBV
ATV
PRG
S+P
CLQ
ART
PRQ
ART

7. Types of Malaria
Plasmodium
Species
Fever Prevalence
P. Falciparum Malignant Tertian Malaria (48 hrs) 65 %
P. Vivax Benign Tertian Malaria (48 hrs) 34 %
P. Malariae Quartern Malaria (72 hrs) Rare
P. Ovale Ovale Tertian Malaria Not found in India

8. Principle Targets of Malaria Vaccine
Based on Vector
P. Falciparum
Pre-erythrocytic
(PE)
Blood Stage (BS)
Transmission
Borne Vaccine
(TBV)
P. Vivax

9. Pre-erythrocytic (PE) Vaccine Approach
(against P. Falciparum)
Target Antigen Outcome
CSP (Circumsporozoite Protein) Inhibits sporozoite adhesion to
hepatocyte.
(On the hepatocyte surface: protelytic cleavage at
region 1 of the N-terminus exposes the adhesive part
of , thereby priming the parasites for invasion of the
liver.)
Irradiated Sporozoites Retain their immunogenicity but lose their
virulence
CelTOS (Cell-traversal protein for ookinetes
and sporozoites )
Abolishes hepatocyte entry of the parasite
(Present in micronemes that are organelles for parasite
invasive motility. )

10. Blood Stage (BS) approach
(against P. Falciparum)
Antigens used Outcome
EBA 175 (Erythrocyte Binding Antigen
175)
Inhibits merozoite invasion into
erythrocytes via Glycophorin A
MSP 1 (Merozoite Surface Protein 1) Inhibits merozoite invasion into
erythrocytes via Band 3 (Anion Exchanger
1 of the RBC)
AMA 1 (Apical Membrane Antigen 1) Inhibits merozoite interaction with RBC

11. Transmission Blocking Vaccine
(against P. Falciparum)
Target Antigen Outcome
Pfs 48/45 Ligand in the fertilisation process
(exact locatin of epitope unknown)
Pfs 230 -same-

12. Approaches that target P. Vivax
Antigens used Outcome
CSP (Circumsporozoite Protein) Inhibits sporozoite binding to hepatocyte
DBP (Duffy Binding Protein) Prevents Duffy antigen mediated entry of
merozoites into erythrocytes via DARC
(Duffy Antigen/Receptor Complex)

13. RTS,SA (Mosquirix)
Only Anti-Malarial Vaccine approved by European Medicines Agency(EMA) in
July 2015 for use in Malaria endemic regions.
It is also the first vaccine licensed for use against any kind of parasitic disease.
Year Development
1984 Early development of RTS,S
2009 Phase 3 trials conducted in seven African countries
2011 Result of Phase 3 trial published
2014 Result of “Extended” Phase 3 trial published
2015+ WHO gives a positive regulatory approval for use in African countries as
per Local Regulations

14. CSP is composed of
• an N-terminal region that binds heparin sulfate proteoglycans
• a central region containing a four-amino-acid (NANP) repeat,
• and a GPI-anchored C-terminal region containing a
thrombospondin-like domain (TLD).
HBsAg particle serves as an carrier for RTS,S, which is fused to
the CSP segment.
Immunogenicity is induced primarily via
• One B cell epitope
• Three T cell epitopes.
TLD
CSP
RTS
GPI
Cont.

15. Recombinant vaccine is expressed in Yeast cells and includes adjuvant
(AS01).
Adjuvant is composed of:
• Monophosphoryl lipid (MPL): binds to TLR-4 and induces innate
immunity.
• Quillaja Saponaira: induces Ig G.
• Emulsion oil: mimics Lipo Polysaccharide (LPS).
Nomenclature
• R: central Repeat region
• T: T cell epitopes
• S: Surface antigen of HBV (HBsAg) attached to C-region
• S: Saccharomyces cerevisiae (Yeast)
• A: Adjuvant

16. “Extended” Phase 3 trials
Carried out between March 2009 and January 2014.
Site: 11 centers in 7 countries.
Total of 15,459 children.
Participants:
• Children (Aged: 5-17 months)
• Young Infants (Aged: 6-12 weeks)
Divided into three groups.
Randomly assigned to receive 3 doses of vaccine or a
comparator/contrl at months 0, 1 and 2 and a booster dose at
month 20.
Cont.

17. Control Vaccine: Rabies Vaccine (also endemic in these
countries)
Control Booster: Meningococcal Vaccine (also prevalent)

18. Primary Objectives
• Measuring Vaccine Efficacy
• Measuring Vaccine Immunogenicity
• Safety (Adverse Events)
Primary Endpoint:
Occurrence of Clinical Malaria i.e.
• Parasitemia > 5,000/ uL
• Axillary Temperature > 37.5 °C

19. Vaccine Efficacy
15,459
participants
8,922 Children
(Age: 5-17 mo.)
No. of cases of
Clinical Malaria
C3C
9,585
R3R
6,616
Vaccine Efficacy
36.3%
R3C
7,396
VE
28.3%
6537 Young
Infants
(Age: 6-12 wk.)
No. of cases of
Clinical Malaria
C3C
6,170
R3R
4,993
VE
25.9%
R3C
5,444
VE
18.3%

20. Vaccine Efficacy (w.r.t. Severe Malaria)
15,459
participants
8,922 Children
(Age: 5-17 mo.)
No. of cases of
Severe Malaria
C3C
171
R3R
116
Vaccine
Efficacy
32.2%
R3C
169
VE
1.1%
6,537 Young
Infants
(Age: 6-12 wk.)
No. of cases of
Severe Malaria
C3C
116
R3R
96
VE
17.3%
R3C
104
VE
10.3%

21. Vaccine Immunogenicity
Anti-CSP Antibody
(Measured via
ELISA)
Measured at 1
month after
booster dose
Children
(Age: 5-17 mo.)
R3R
318.2 EU/ml
R3C
34.2
Young Infants
(Age: 6-12 wk.)
R3R
169.9
R3C
6.2
12 Months after
booster dose
Children
(Age: 5-17 mo.)
R3R
52.4
R3C
19.3
Young Infants
(Age: 5 -17 mo.)
R3R
15.9
R3C
3.7

22. Adverse Effects
(within 30 days)
Children
(Age: 5-17 mo.)
R3R+R3C
86.1%
C3C
86.8%
Young Infants
(Age: 6-12 wk.)
R3R+R3C
79.4%
C3C
89.3%
Safety

23. Adverse Events:
• Local site reactions (Pain, redness and swelling )
• Drowsiness
• Irritability
• Loss of appetite
• Fever (Most common symptom)
Serious Adverse Events:
• Meningitis
• Febrile Convulsions

24. Fever
Children
(Age: 5-17 mo.)
Fever
(>37.5 °C)
R3R+R3C
31.1%
C3C
13.4%
Grade 3 fever
(>39 °C)
R3R+R3C
2.5%
C3C
1.1%
Young Infants
(Age: 6-12 wk)
Fever
(<37.5 °C)
R3R+R3C
30.6%
C3C
21.1%

25. Challenges in making an Anti-Malarial Vaccine
Applying the Traditional Approach
Animal Models
Waning Effect of Vaccines

26. 1. Applying the Traditional Approach
• Traditional approaches to vaccine production include
inoculation via:
• Traditional Methods have failed. All Plasmodium species have
distinct forms in both human and mosquito stages for their
life cycle.
• Preventing PE stage from initiating is the only method that
wards off sign and symptoms of Malaria.
Live Attenuated Vaccine
Killed Whole organisms

27. 2. Animal Models
• Good Model: Pathological and clinical alterations should mimic the
human response.
• Humans have a diverse genetic background that has a profound
influence on the immune response.
• Most animal models: Inbred and homogenous.
• Data resulting from experimental does not automatically
extrapolate to the disease in humans
• Apart from RTS,S, other vaccine attempts have not been successful”
based on mouse models.
• This limitation can be solved by the use of outbreed large animal
models that are more closely related to humans, like dogs and non-
human primates.
• Aotus Gri-sei-membra represents the best current malaria primate
model because of its high susceptibility to infection by blood forms
and sporozoites of both species of Plasmodium

28. 3. Waning Effect of Vaccines
Vaccine Efficacy
Phase 3 Trials
(1 year after
booster dose)
Children
(Age: 5-17 mo.)
55.8%
Young Infants
(Age: 6-12 wk.)
31.3%
Extended Phase
3 Trials
(2009-2014)
Children
(Age: 5-17 mo.)
28%
Young Infants
(Age: 6-12 wk.)
18%

29. Newer Projects in India
and their status
JAIVAC-1
JAIVAC-2
PvDBP II
PfCHMI

30. JAIVAC-1
Indication Plasmodium Falciparum Malaria
Target Antigen RECOMBINANT VACCINE
-PfMSP-119
-PfF2 (receptor-binding F2 domain of EBA175)
Route Intramuscular
Adjuvant Montanide (oil emulsion)
Clinical Development Phase 1 complete (April 2015)
Dose Three doses (10 μg, 25 μg and 50 μg of each antigen) on Day 0, Day
28 and Day 180
Study Endpoint -Assessment of safety of the study vaccines
-Check Immunogenicity of the Antigen
Results -No serious side effect noticed.
-All subjects sero-converted for PfF2 but elicited poor immune
response to PfMSP-119.
-The antibodies against PfF2 were predominantly of IgG1 and IgG3
isotype.
Conclusion Antigen PfF2 should be retained as a component of a malaria
vaccine but PfMSP-119 construct needs to be optimised (improve
efficiency) to improve its immunogenicity.

31. Anti-PfF2 and PfMSP-119 antibody levels measured by ELISA in sera collected
from Day 0 to Day 365

32. JAIVAC-2
Indication Plasmodium Falciparum Malaria
Target Antigen RECOMBINANT VACCINE
-PfMSP-Fu24
-PfF2 (receptor-binding F2 domain of
EBA175)
Route Intramuscular
Development Under Manufacture for Phase 1 trials
Biological Rationale PfMSP-Fu24 (Fu: Fusion):
Chimeric fusion between PfMSP-119 and
PfMSP-3 that contains a T-helper epitope
and B-cell epitope
Pre-Clinical Study Increased Efficacy (Unpublished Data)

33. PvDBP II
Indication Plasmodium Vivax Malaria
Target Antigen PvDBP II :
39 kDa cysteine rich region on the Duffy
Binding Protein of P. Vivax
Route Intramuscular
Development Under manufacture
Biological Rationale PvDBP II is a critical domain necessary for
interaction between P. Vivax to the RBC.
Thus, blocking this functionally important
component prevents the erythrocytic
stage of Malaria from occuring.

34. PF-CHMI (CONTROLLEDHUMANMALARIAINITIATIVE)
CHMI studies: Healthy volunteers are infected with Plasmodium falciparum to assess the efficacy
of novel malaria vaccines.
Have become a vital tool to accelerate vaccine development.
CHMI studies provide a cost-effective way to circumvent the use of large-scale field efficacy
studies.
However, to date few modern CHMI studies have been performed in malaria-endemic countries.
Indication Plasmodium Falciparum Malaria
Study Intervention Sporozites of P. Falciparum NF54 strain
delivered via laboratory reared An.
Stephensi mosquitoes.
Route Anopheles bite on the ventral aspect of
forearm
Objective To standardize the CHMI model in India
Biological Rationale Widely accepted as a safe and informative
initial step in evaluating the efficacy of
pre-erythrocytic stage vaccines

35. Plasmodium falciparum NF54
• It is a transgenic
Plasmodium parasite that
expresses a luciferase
transgene throughout the
life cycle.
• Luciferase expression is
robust and measurable at
all life cycle stages,
including midgut oocyst,
salivary gland sporozoites
and liver stages Fluorescent Microscopy

36. Ethical Issues
•
1. Controlled infection studies
2. Human landing catches

37. 1. Controlled infection studies
*
•Participants often experience significant acute symptoms—including fever, headache, joint
and muscle pains, and even cardiac events—which go beyond many definitions of ‘minimal
harm’ that are commonly employed in the ethical assessment of non-therapeutic research
*
•Further, malaria infection studies often involve exposure to blood products via mosquitoes or
injection, which poses the risk of transmitting other infections and prion diseases. Finally, if
participants are able to leave research centres while still infected, this can pose risks to the
wider community. In all cases, participants must be carefully selected and informed.
*
•Such studies should only occur in contexts with access to affordable quality healthcare, high
standards of research conduct, and robust ethical oversight so that the safety of participants is
ensured

38. 2. Human landing catches
*
• Using human participants act as mosquito ‘traps’.
• Receiving 50–100 mosquito bites in one nightshift
*
• Potential harms to a few individuals are (voluntarily
consented) balanced against benefits to the wider
community
*
• It would nonetheless be ethically preferable to develop
alternative practices that offer no risk to human beings.

39. Thank You