Solid tumor accounts for 90% of
all cancers. The current treatment approach for most solid tumors is surgery;
however it is limited to early stage tumors. Other treatment options such as
chemotherapy and radiotherapy are non-selective, thus causing damage to both
healthy and cancerous tissue.
Recent research has shifted
towards understanding the tumor microenvironment and it's differences from that
of healthy cells/tissues in the body and then to exploit these differences for treatment
of the tumor. One such approach is utilizing anaerobic bacteria. Several strains of bacteria have
been shown to selectively colonize in solid tumors, making them valuable tools
for selective tumor targeting and destruction.
Clostridium-based cancer therapy is a promising approach for
the treatment of solid tumours. Bacterial-based
cancer therapy using Clostridium spp.
offers a selective advantage in overcoming the obstacles of hypoxia and
necrosis. Clostridium spp.,
being strictly anaerobic will only colonize in areas devoid of oxygen, and when
systematically injected, spores germinate and multiply in the hypoxic/necrotic
areas of solid tumors. Clostridium, although anaerobic, possesses the ability to
sporulate, allowing them to remain dormant in environments where oxygen is
present. However, when growth conditions are suitable (i.e., in the
hypoxic/necrotic milieu of solid tumors), the Clostridium spores germinate and begin to colonize these
areas. This aspect of Clostridium growth
is being exploited for use in a number of various novel cancer treatment
strategies currently being developed which utilize Clostridium as a
vector to deliver therapeutics directly to the solid tumor site. Clostridial
vectors can be safely administered as spores, and their efficacy in delivering
and secreting therapeutic proteins has been demonstrated in a number of
preclinical trials.
Clostridium spp. with spore formation.
