Oncolytic viruses: a cure through an infection

1. Major credit seminar
Oncolytic viruses – a cure through an
infection
Chaple Ashwini R.
Ph.D Scholar
P-2074

2.  Introduction
 Cancer-selective mechanisms of OVs
 Mechanisms of OVs action
 Arming of OVs
 Approval winning OVs
 Features distinguishing from other therapeutics
 Conclusion and future perspectives
Contents

3.  Class of therapeutic agents that promote antitumor responses through a
dual mechanism of action that is dependent on selective tumor cell killing
and induction of systemic anti-tumor immunity
Oncolytic viruses (OVs)
ONCO = CANCER ; LYTIC = KILLER
Naturally preferring cancer cells
• Reovirus
• Poliovirus
• Myxoma virus
• Coxsackievirus
• Echovirus
• Newcastle disease virus
• Vesicular stomatitis virus
Genenically manipulated
• Adenovirus
• Measles virus
• Vaccinia virus
• Influenza virus
(Hyeon et al., 2015)

4. 1904 : G. Dock published report - woman who experienced remission
from myelogenous leukemia after influenza infection (1896)
Influenza proven to be a virus 37 years later
History : Viruses fighting cancer

5.  1912 : De Pace reported a cervical cancer patient free from disease following
injection of rabies vaccine after bitten by a rabid dog
 1923 : Lavditi and Nicolau - Tumors are more susceptible to viruses than
normal cells, and tumors act as a sponge attracting viral replication
 1940s : wild type murine viruses
given intravenously to mice –
suppressed tumors, killed mice
(Kelly et al., 2017)
History : Viruses fighting cancer

6. • Poliovirus, Echovirus - natural
• Adenovirus, measles virus, VSV - artificial
1.Targeting cancer
cell surface Ags
• Reovirus - selective infectivity and high
replication by RAS pathway
• VSV - high replication cells due to lower
antiviral responses
2.Cancer-selective
replication
• Proteases overexpressed - reovirus
• Matrix metalloproteinase 2 high level –
measles virus, NDV (F protein
modification)
3. Targeting cancer
microenvironment
Cancer-selective mechanisms of OVs
(Cho et al., 2015)

7. Mechanism of OV action
(Filley et al., 2017)
I. Direct virus oncolysis - tumor cell killing by virus replication
II. Cytotoxicity of viral proteins - directly kill cell before replication-
mediated lysis
e.g. E3 death protein and E4orf4 proteins encoded by adenovirus
(Demeke et al., 2016)
Oncolytic virotherapy -
Kirn in 2001

8. Rommelaere et al – used term oncolytic immunotherapy in 2011
III. Induction of antitumoral immunity
IV. Destroying tumor vasculature
(Mullen et al., 2016)
(Guo et al., 2017)
Mechanism of OV action

9. For the Efficacy OVs must be :
- capable of penetrating host defenses to access tumors
- capable of propagating to target site before infection is controlled
and eliminated by immune system
“It’s not always what you deliver, But also how you deliver”
(Maroun et al., 2017)
Resistance to OV by immune system
(Filley et al., 2017)

10.  Pretreatment with immunosuppressive chemotherapeutics –
cyclophosphamide
 Pretreatment with an angiogenesis inhibitor - reduce vascular
permeability, inflammation, and leukocyte infiltration
 Histone deacetylase inhibitors (HDIs) - reduce the cellular antiviral
immune response, impeding type I IFN response
 Polymer Coating
Alternative approach ………….. Engineered (armed) OVs
(Prestwich et al., 2009 ; Filley et al., 2017)
How to overcome the resistance offered by
immune system???

11. Targeting transduction -
modification of viral surface
proteins
Targeting transcription –
tumor specific promoters
Targeting translation
Targeting pro-apoptosis
Immunostimulatory genes -
boost immune responses
Prodrug-converting
enzyme genes
Genes encoding
inhibitors of
angiogenesis
Arming of oncolytic viruses

12. By displaying single chain antibodies or other polypeptide binding ligands on
the viral surface
 MV retargeted against human uPAR
(MV-h-uPA) - Specifically infect
cancer cells overexpressing uPAR
 Modified AdV to create cancer-
selective virus as CAR expressed in
both normal cells and cancer cells
Targeting transduction
(Lin et al., 2017)

13. Placing essential viral gene under regulation of tumor specific promoter
 Human telomerase reverse
transcriptase (hTERT) - OBP-301
(Telomelysin®)
 Prostrate specific antigen (PSA) -
CV706
 Hypoxia-inducible factor-1
 α-fetoprotein
Targeting transcription
( Lin et al., 2017)

14.  OV engineered to disable viral proteins that antagonize the cellular
interferon (IFN) response
 VSV - M protein mutation : selective replication in cancer cells
Targeting translation
(Russell et al., 2016)

15. OVs engineered to disable viral proteins that prevent apoptosis
Targeting pro-apoptosis
(Russell et al., 2016)

16. Cytokines /
Chemokine
Additive immunogenic effect viruses
GM-CSF promotes DC recruitment and maturation HSV (T-Vec)
AdV
MV
IL-12 Infiltration of macrophages, Th, CTL and NK cells VSV
NDV
AdV
IL-2 and IL-15 Infiltration of T helper and CTL VSV
NDV
HSV
IFN-γ Increased cytokine expression and improved DC
maturation
VSV
NDV
CCL5
CCL2
CCL9
CXCL11
Improved DC maturation
Improved infiltration T helper cells and CTLs
VV
HSV
(Graaf et al., 2018)
Immunostimulatory genes

17. (Cheema et al., 2017)
ganciclovir ganciclovir triphosphate
5-fluorocytosine 5-fluorouracil
fludarabine phosphate 2-fluoroadenine
TK
CD
PNP
HSV-TK
CD
PN
Prodrug-converting enzyme genes

18. • oAdV – expressing VEGI
• VV (TK- and vaccinia GF-deleted) expressing
VEGF-1-Ig- binds VEGF (Hou et al., 2014)
Targeting vascular
endothelial growth
factor
• Conditionally replication competent Ad
expressing TIMP3
• oHSV in combination with TIMP-3
• (Wong et al., 2010)
Targeting matrix
metalloproteinase
• MV-E:A encodes human or murine
endostatin/angiostatin fusion protein (MV-hE:A
and MV-mE:A ) (Tysome et al., 2013)
Antiangiogenic
peptides
Genes encoding inhibitors of angiogenesis

19. New approches for arming OVs

20.  OVs encoding immune checkpoint modulator(s) – antagonizes activity of
checkpoint inhibitors
 T cell inhibitory factors : cytotoxic T lymphocyte antigen 4
(CTLA-4), programmed death-1 (PD-1) and its ligand programmed death-1
ligand 1 (PD-L1)
 CTLA-4 competes with CD28(costimulatory T cell molecule) for B7
ligands : decreases T cell proliferation
 PD-1 expressed on activated T cells binds to its ligand PD-L1 on tumor
cells : T cell exhaustion
(Christine Engeland et al., 2014)
Checkpoint inhibitors
 Blockade of CTLA-4 (by anti-CTLA-4) and PD-1 (antiPD-1) or PD-L1
stimulates effector T cells to produce antitumor responses
(Raman et al., 2015)

21. (Sheng et al., 2017)
 T-cell engager (CD3-scFv, single- chain
variable fragment) : alternative approach to
engage T cells
 BiTEs : CD3-scFv and scFv specific for tumor
cell surface Ag
 Triggers T-cell activation : proteases and
cytokines release kill tumor cell
oVACV encoding secretory BiTE - for CD3 and tumor cell surface Ag EphA2
oAdV encoding BiTE - target EGFR and CD3 (ICOVIR-15K-cBiTE)
Combination with Bispecific T-Cell Engagers
(BiTEs)
(Wing et al., 2018)

22. viral genome with transgenes – express
NIS and accumulate iodine
 Combination with radioiodine -
local radiotherapy of tumour
 Enhance tumor cell death - termed
as radiovirotherapy
Visualise viral replication
 Study with adenovirus, measles
virus and vaccinia virus
(Miller et al., 2015)
Noninvasive tracking of viral distribution and replication renders it highly
relevant to monitor the fate of oncolytic infection
NIS reporter gene - “how much, when, and where”
(Mohanan et al., 2017)

23. cancer stem cell (CSCs) resist conventional therapies
OVs not affected by these features- replicate in CSCs
OVs Targeting CSCs
(Ribacka et al., 2015)
(Chaurasiya et al., 2018)

24. Cancer-fighting viruses win approval
“Viruses are great tools for helping us to understand how the antitumor
immune response works,” said Dr. Fueyo. “What we learn from viruses
will help us move the field of immunotherapy forward.

25. Approval :
2015 – FDA for melanoma
2016 - European and
Australian health agencies
 HSV-1, ICP34.5 and ICP47 deleted
 US11 promoted, armed with hGM-CSF
T-VEC (talimogene laherparepvec, Imlygic)
(Hughes et al., 2013)

26.  Triple-mutated HSV-1 developed by Todo et al.
 3 Deletions - ICP34.5, ICP47 and ICP6 in G207( T-vec)
 Insertion of E.coli LacZ gene
 ICP6 encodes ribonucleotide reductase (RR) : viral DNA synthesis
 Inactivated ICP6 : replication only in cells expressing high host RR
 Phase II study started in 2015 – Glioblastoma
 Feb 2016 - designated as 'Sakigake' (ahead of world) breakthrough
therapy drug in Japan
G47Δ
(Fukuhara et al., 2016)

27.  Genetically modified wild AdV type 5 : E1B-55KD and E3 deletion
 Selectively replicate in cells with dysfunctional p53 genes
 Approved in 2005 in China - head and neck cancer
 1st commercialized oncolytic virus – by Shanghai Sunway Biotech
(Choi et al., 2015)
Oncorine (H101)

28.  JX-594 : Vaccinia vaccine (Wyeth strain)
 Phase III trial - hepatocellular carcinoma (Sponsored by SillaJen)
 FDA Orpahn drug designation – 2013
(Kim et al., 2013)
JX-594 (Pexa-Vec, Pexastimogene devacirepvec)
(Source –Jennerex)

29. Virus Product name Virus
Modifications
Targeted Tumor Clinical Trial
Phase
Adenovirus Onyx-015 E1B deletion Lung metastasis 1 - completed
CG0070 E3 deletion; GM-
CSF insertion
Bladder cancer 2/3- ongoing
Coxsackie virus
(CVA21)
Cavatak Unmodified
Coxsackie virus
A21
Melanoma 2 - ongoing
Newcastle disease
virus
PV-701 Attenuated Solid tumor 1- completed
Poliovirus (Sabin) PVS-RIPO Rhinovirus IRES Glioma 1- ongoing
Vesicular
stomatitis virus
(Indiana)
VSV-hIFNb IFN-β hepatocellular
carcinoma
1- ongoing
(Matsuda et al., 2017)
Current clinical development status of oncolytic virus therapy

30. Features distinguishing OV from conventional
therapeutic modalities
• Replication in tumor-selective fashion
• Target multiple pathways
• Low probability for generation of resistance
• Minimal systemic toxicity
• Virus dose increases with time - in situ virus amplification
• Safety features can be built in
(Chiocca and Rabkin, 2014)

31. Conclusion
 OVs are structurally and biologically diverse, spreading through tumors and killing
tumor cells by multiple mechanisms
 They can also cross-prime and amplify antitumor immunity, serving as a cancer
immunotherapy
Oncolytic immunotherapy can be viewed as a race between the spreading virus and
the responding immune system
 Arming of oncolytic viruses elicit specificity, potency and safety
 Development of combination protocols implementing antitumor agents are capable
of yielding additive or synergistic antitumor benefits
Goal of oncolytic therapy - to exploit innate ability of existing viruses and
engineering or tailoring them to infect tumor cell and produce selective oncolysis
while sparing normal cells

32. Future perspectives
A new era of cancer treatment seems at down, where cancer patient can
freely choose oncolytic virus therapy as a treatment option
 There are many hurdles that must still be overcome
 Investigation of mechanisms underlying resistance to oncolytic
immunotherapy and OV-associated toxicities
 Research on oncolytic viruses may yield insights into the use of current
immunotherapies

33. Thank you
“We used to think only about making viruses better - more powerful - at
killing tumor cells, Now we need to find ways to help viruses enhance the
immune response.”