251provided evidence of clinical activity only in a minority of patients despite inducing
immunization in up to 50 % of them. Different approaches have been developed
recently in order to induce stronger peptide-induced immune-mediated tumor
growth control, possibly translating into improved clinical response rates, with spe-
cifi c focus on multipeptide-based anticancer vaccines (Pilla et al. 2009 ). This strat-
egy offers many advantages, such as the possibility of bypassing tumor heterogeneity
and selection of antigen-negative clones escaping peptide-specifi c immune
responses, or combining HLA class I- and class II-restricted epitopes, thus eliciting
both CD4- and CD8-mediated immune recognition. Notably, advances in antigen
discovery technologies permit further optimization of peptide selection, in terms of
identifi cation of tumor-specifi c and unique TAA as well as antigens derived from
different tumor microenvironment cell components. With the ultimate goal of com-
bining peptide selection with patient-specifi c immunogenic profi le, peptide based
anticancer vaccines remain a promising personalized treatment for cancer patients,
as shown by of preclinical and clinical studies. Use of personalized peptide vaccina-
tion combined with chemotherapy has been explored for cancer patients, e.g. those
with breast and prostate cancers, which are described under the cancers of respec-
tive organs in a following section.
Current Status and Future Prospects of Personalized
Cancer Vaccines
This article has identifi ed some of the important technologies and given examples
of their application. The review of current state of technologies relevant to cancer
indicates good prospects for the development of personalized cancer therapies.
Some of the current clinical trials of personalized cancer vaccines are shown in
Table 10.4.
Numerous other clinical trials of cancer vaccines have been conducted with a
high failure rate. Reasons for failure include the following:
- The immune system is already damaged by chemotherapy in some patients and
may not respond to vaccines. - Vaccines based on a single antigen are less effective than those that to raise an
immune response against a broad range of tumor antigens to minimize the chance
of the tumor becoming resistant to the therapy. - Immune response to vaccine may take a few months to evolve and tumors that
grow rapidly may outpace it. - Some cancer patients with advanced and bulky tumors are not good subjects for
immunotherapy.
Personalized Cancer Vaccines