Page 103 - Bio Engineering Approaches to Cancer Diagnosis and Treatment

4.6 Cancer vaccine 101

viruses with immune alerting ability. These viruses have become famous in cancer
vaccination due to their direct cytolytic effect on tumor cells. OVs are interesting
candidates in cancer immunology as they can induce immune responses against can-
cer cells [93]. Adenovirus is the most researched OV [94].
Although, adenoviruses (Ad2 and Ad5 are the most common ones) are capable of
TAAs delivering, a lot of people are shown low immunity against adenovirus due to
long time exposure and hence produced two similar systems [89].
One of the concerns about these vaccines is that, the usage of attenuated live
viruses in patients who have recently taken chemotherapy may cause frank infection
or other health problems [94].
In one study, scientists have produced two vaccines: (1) with two different viruses
and (2) combination of virus and bacteria. They have used combination of virus and
bacteria in order to compare the results. They have produced two similar systems,
one of them with adenovirus (Ad) and Maraba (MRB) and the other one with Lm
which is a bacteria and Maraba (MRB) which is virus. Both vaccines administrated
in mice models. Although both vaccines have shown sufficient immune response, the
mice have shown smaller tumor size and longer survival in bacterial-viral system in
contrast to the usage of different two viruses [96].

4.6.5 Biomaterials in delivery and targeting
One of the most crucial factors in cancer vaccination is targeting, and over the past
decade scientists have been faced with problems of insufficient delivery. Hence,
some new delivery systems have been invented and they have shown promising
results. Different kinds of targeting and delivery systems including nano- and micro-
particles, scaffolds, and self-assembling materials have been prepared and used with
different cancer vaccine strategies [70]. In this chapter two vital delivery system have
been discussed:

• Cancer vaccines on the basis of nanoparticles
Targeting systems are made of polymers and lipids, in the following paragraph
most famous nanoparticles have been discussed:
Liposomes considered to be one of the first used nano materials for cancer vac-
cination, that is, resulted from the FDA approval of these materials and their deliv-
ery capability. These two reasons causing liposomes as a promising candidate for
vaccine delivery. On the other hand, some drawbacks in their loading capability,
stability and toxicity limited their usage. PLGA is the other crucial nanoparticle for
vaccine delivery. Although PLGA can be manufactured easily and can be prepared in
different particle sizes, however, the low (drug) loading amount is one of the ongoing
problems. In order to compare these two most used nanoparticles, it is worth mention
that liposomes contain both hydrophobic and hydrophilic bonds which lead them to
be suitable for carrying both hydrophobic and hydrophilic components at the same
place. However, PLGA mostly contains of hydrophilic bonds results in a low hydro-
phobic loading capacity. To overcome the aforementioned obstacles scientists have