Page 104 - Bio Engineering Approaches to Cancer Diagnosis and Treatment

102 CHAPTER 4 Immunotherapy

worked on modification strategies to stabilize and enhance the loading rate of both
Liposomes and PLGA [70].

• Cancer vaccines on basis of scaffolds
The reason why scientists are motivated to use scaffolds is due to the benefits of
local delivery systems. Local delivery may decrease the systemic toxicity and boost
the immune effect with lower doses [97].
Scaffold delivery systems mainly have made of polymers and hydrogels. These
systems are typically large, so they remain in the injection site. Moreover, scaffold
base delivery systems are capable in encapsulation of different molecules.
There are three efficient materials that have been used as cancer vaccines scaffolds,
including PLGA, hydrogels which mainly contains of alginate and mesoporous silica
micro-rods (MSRs), these scaffolds are all biodegradable and biocompatible [70].
The scaffolds play a key role in mimicking the natural lymph node function,
so they are vital for immune cells to interact and expand. Based on these points,
some factors in scaffold fabrication seems demanding, like: porosity and intercon-
nection between porous which are essential for cell nutrition and cell encapsulation
respectively, hence scaffolds must meet some factors, including: rigidity to bear
the forces, porosity to provide convenient penetration, and control the signaling
maters [97].
In conclusion, combination of biomaterials with cancer vaccines has shown
promising results by reducing the dosage, increasing the safety due to their local-
ized administration, boosting the efficiency resulted from their targeting ability
and also biomaterials can influence on signaling. However, some obstacles exist
in their usage: First, there are far differences between academic researches and
clinical trials, animals may be treated in a different way from humans when they
faced to biomaterials. Second, most of the investigations on biomaterials for can-
cer vaccination approaches have been done on melanoma which is different from
solid and hematological tumors, so implantation seems to be different from cancer
to cancer. Finally, some troubles in commercial and clinical purposes have been
happened, including: the large scale production, and FDA approval. In order to
facilitate the clinical trial phases it is better to use FDA approved biomaterials like
PLGA [70,71].
It is worth noting that, on one side, designing suitable preclinical platforms for
cancer vaccines is difficult due to the differences in human and mouse immune sys-
tems. On the other hand, mouse tumors may not always mimic human cancers in
reality [89].

4.6.6 Case study
Maslak et al. have succeeded to produce a vaccine named galinpepimut-S against
WT1 protein as a treatment for those who suffer from AML. In phase II study
patients were administered vaccines for at least six doses in 10 weeks. The results
have revealed that the vaccine is well tolerated and 22 patients were well treated [98].