This document discusses using bacteria for cancer therapy. It describes how certain bacteria can target and kill tumor cells, including some that are currently in clinical trials. Obligate anaerobes like Clostridium target low-oxygen areas of tumors, while facultative anaerobes like Salmonella can detect and penetrate tumors. Genetically modified Salmonella and Clostridium have shown efficacy in preclinical studies and early clinical trials. Bacteria can also be used as vectors to deliver gene therapy or anticancer agents directly to tumors. Overall, the document argues that bacteria show promise as novel anticancer agents.

1. BACTERIA IN CANCER THERAPY
Presented by – GAURAV GANGWAR

2. INTRODUCTION
• Therapies like photodynamic therapy,
HAMLET(human alpha-lactalbumin made lethal
to tumor cell), gene therapy, complementary
and alternative therapy etc. are intended or
claimed to treat cancer.
• But a Live, attenuated, genetically modified,
non-pathogenic bacterial species and bacterial
spores are also capable of inhibiting the growth
of cancer.
• The most potential and promising strategy is
bacteria based gene-directed enzyme prodrug
therapy.

3. HISTORY
• Observation of German physicians W. busch &
F. fehleisen..
• American physician William coley.
‘coley’s toxins’ – Two heat killed bacterial
species, Salmonella pyogenes and serratia
marcescens.

4. BACTERIAL TARGET OF TUMOR
• Obligate anaerobes (e.g Clostridium and
bifidobacterium)
- target the anoxic area of tumor, and inhibit
the growth of tumor.
• Facultative anaerobes (e.g. Salmonella and
Escherichia)
• - identify and penetrate tumors by detecting
and chemotaxising towards small molecule
gradients of serine, aspartate and ribose.

5. BACTERIA AS TUMORICIDAL AGENT
• Clostridium novyi–NT (attenuated clostridium strain) produce
toxicity in tumor even after deletion of genes coding for a
lethal toxin.
• COBALT(combination bacteriolytic therapy)- Clostridium novyi-
NT spores were administered in combination with conventional
chemotherapeutic agents like dolastatin-10, mitomycin C,
vinorelbine and docetaxel.
• Bacillus Calmette Guerin(BCG),the most successful bacterial
agent so far is used specifically for the treatment of superficial
bladder cancer
• Salmonella strain VNP20009-after deletion of two genes msb &
purl results in its complete attenuation.
-VNP20009 has been successfully investigated in phase 1
clinical trials in cancer patients.

6. BACTERIA AS VECTOR FOR GENE
THERAPY AND TUMORICIDAL AGENT
• For delivering anticancer agents, cytotoxic
peptides, therapeutics protein or produrg
converting enzymes.
e.g. Salmonella
• Two reports showed that when transfer of
anti-angiogenic genes (thrombospondin and
endostain) from salmonella, prevent the
formations of new blood vessel and stopped
the nutrient supply in tumor cell.

7. • Attenuated selmonella typhimurium- used to
deliver cytokines(IL-2) locally to liver cancer.
• Various therapeutic proteins, including TNF-alpha
and platelet factor 4 fragment, have been cloned
and expressed in VNP20009.
• Bifidobacterium adolescentis spore administration
via tail vein of tumor-bearing mice resulted in
strong inhibition of angiogenesis.
• Functional TNF- alpha has been cloned and
expressed in C. acetobutylicum.

8. BACTERIA DIRECTED ENZYME
PRODURG THERAPY
• Cytosine deaminase (CD) have been successfully expressed
in C. sporogenes and C. acetobutylicum.
-convert 5-fluorocytosine(5FC) to 5-fluorouracil(5FC).
• Salmonella vector has also been combined with CD and
nitroreductase, and success has been observed in vivo and
it is currently undergoing in phase 1 clinical trials.
• TAPET(Tumor Amplified Protein Expression Therapy) uses
VNP20009 expresses an E.coli CD for preferentially
delivering anti-cancer drug to solid tumor.
• Salmonella + carboxypeptidase G2(enzyme convert
mustard prodrug to DNA cross-linking agent) show
significant results in vivo.

9. BACTERIAL TOXINS FOR CANCER
• Cyclomodulins- bacterial toxins that subvert the host
eukaryotic cell cycle.
E.g. 1. CNF(from E.coli) –cytotoxic necrosis factors, a cell-
cycle stimulator.
- triggers the G1 - S transition and induces DNA
replication.
2. CDTs (cytolethal distending toxins) found in several
Gram- negative bacteria,
-cell-cycle inhibitor
3.Cif from enteropathogenic and enteroheamorrhagic
E.coli,
- block mitosis and inhibit clonal expansion of
lymphocytes.

10. -Bacterial toxins binding to surface antigens
• Pseudomonas exotoxin A inhibit protein synthesis by
catalytically ribosylate EF-2.
• Clostridium perfringens enterotoxic (CPE) investigated
for colon, breast, and gastric cancers due to its
cytotoxic property.
• Botulinum neurotoxin(BoNT) briefly opens tumors
vessels, allowing more effective destruction of cancer
by radiotherapy and chemotherapy.
• Some other toxins undergoing on research are
- alfa toxin from Stapylococcous aureus,
- AC-toxins from Bordetella pertussis
- shiga like toxins
- cholera toxin

11. -BACTERIAL TOXIN CONJUGATED TO LIGAND
• Binding of toxins to cell-binding proteins .e.g
Monoclonol antibodies or growth factors, cause
regression in growth of cancer by targetting them
into the specific sites on cancers.
• For example transferrin-Diphtheria toxin(DT), DT-
epidermal growth factor(EGF) in brain tumor and
metastatic carcinomas and IL4-PE against human
gliboblastoma tumor
• Genetically modified and recombinant toxins e.g
chimeric toxins

12. BACTERIA AS IMMUNOTHERAPEUTIC
AGENTS
• Genetically engineered Attenuated Salmonella
typhimurium expressing murine cytokines (IL-2)
suppress the growth of tumor.
• Xenogenic DNA vaccine encoding tumor endothelial
markers 8(TEM8) carried by attenuated S.typhimurium
has been repoetd to generate TEM8-specific CD8
cytotoxic T-cell response after oral administration.
• C.novyi spores after systematic administration destroy
adjacent cancer cell and trigger an inflammatory
reaction by producing cytokinies such as IL-6, MIP-2, G-
CSF, TIMP-1 and KC…

13. • CANCER VACCINE- A recombinant Listeria
monocytogenes( facultative intracellular
bacteria) vaccine strain expressing nucleoprotein
(NP)from influenza strainA/PR8/34 has shown
great therapeutic potential pre-clinically by
regressing growth off microscopic tumors.
• Bacillus calmette-gurein (BCG-CWS) has been
used as an effective adjuvent for
immunotherapy.

15. PROBLEMS WITH BACTERIAL
THERAPY
• Toxicity
• Infections
• Incomplete tumor lysis
• DNA mutation

16. Conclusion
• Live, attenuated bacteria as antitumor agents
and vectors for gene directed enzyme prodrug
therapy have emerged as potential strategies.
• VNP20009 and TAPET-CD have been
investigated successfully in phase 1 clinical
trial.
• Chemeric toxins are also being investigated as
future toxin-based anticancer therapies.

17. IMPORTANT CLINICAL TRIAL INVOLVING BACTERIAL
INTERVENTION IN CANCER
INTERVENTION CLINICAL PRESENT STATUS DISEASE
(NUMBER TRAIL PHASE CONDITION
COMPOUND)
VNP20009 PHASE 1 COMPLETED ADVANCED
OR METASTATIC
SOLID TUMORS
TAPET-CD HEAD, NECK
PHASE 1 COMPLETED ESOPHAGUS CANCER
Tf-CRM 107 PHASE 1 ONGOING BRAIN ENTRAL NERVOUS
SYSTEM TUMOR
IL4-PE PHASE 1 ONGOING BRAIN ENTRAL NERVOUS
SYSTEM TUMOR
MALIGNANT GILOMA,
GLIBLASTOMA MULTIFORME
IL3-PE PHASE 1 ONGOING ANAPLASTIC ASTROCYTOMA
ANAPLASTIC

18. REFERENCES
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