High-molecular-weight melanoma-associated antigen mimotope immunizations induce antibodies recognizing melanoma cells

Abstract

Size and posttranslational modifications are obstacles in the recombinant expression of high-molecular-weight melanoma-associated antigen (HMW-MAA). Creating a tumor antigen mimic via the phage display technology may be a means to overcome this problem for vaccine design. In this study, we aimed to generate an immunogenic epitope mimic of HMW-MAA. Therefore we screened a linear 9mer phage display peptide library, using the anti-HMW-MAA monoclonal antibody (mAb) 225.28S. This antibody mediates antibody-dependent cellular cytotoxicity (ADCC) and has already been used for anti-idiotype therapy trials. Fifteen peptides were selected by mAb 225.28S in the biopanning procedure. They share a consensus sequence, but show only partial homology to the amino acid sequence of the HMW-MAA core protein, indicating mimicry with a conformational epitope. One mimotope was chosen to be fused to albumin binding protein (ABP) as an immunogenic carrier. Immunoassays with 225.28S indicated that the mimotope fusion protein was folded correctly. Subsequently, the fusion protein was tested for immunogenicity in BALB/c mice. The induced anti-mimotope antibodies recognized HMW-MAA of 518A2 human melanoma cells, whereas sera of mice immunized with the carrier ABP alone showed no reactivity. These anti-mimotope antibodies were capable of inducing specific lysis of 518A2 melanoma cells in ADCC assays with murine effector cells. In conclusion, the presented data indicate that mimotopes fused to an immunogenic carrier are suitable tools to elicit epitope-specific anti-melanoma immune responses.

Induction of IgG antibodies against the GD2 carbohydrate tumor antigen by vaccination with peptide mimotopes

“…By biopanning [37] such phage display libraries with an antibody of interest, epitope mimics, so-called mimotopes, can be selected. These peptides mimic the original antigen by virtue of their 3-D structure, in which the amino acids of the peptide adopt the same shape as the epitope recognized by the selecting antibody [38,39]. Thus, the poorly immunogenic carbohydrate antigens can be converted into peptide epitope mimics, which have a much greater potential of both antigenicity and memory induction.…”

CSPG4: a prototype oncoantigen for translational immunotherapy studies

“…Alternative strategies evaluating in a pre-clinical setting the impact of the fusion of mAb MK2-23 with IL-2 demonstrated an enhanced immunogenicity of the novel construct and thus the possibility to bypass the requirement for conjugation to a carrier and administration with an adjuvant [106]. Moreover, anti-CSPG4 vaccination was again of interest when the mimotope technology emerged, indeed immunizations with CSPG4 mimotopes resulted in an inhibition of proliferation, migration and invasion of CSPG4-positive melanoma cells through the induction of a specific antibody response responsible for both immunological and non-immunological antitumor functions [107–109]. …”

Phage display and its application in vaccine design

“…It is difficult to ensure that all conformationally active epitopes will be displayed correctly on the phage surface. Since phages require a prokaryotic host for growth, eukaryotic glycosylation signals will be absent from the phage vaccine, and there is a risk of filamentous bacteriophages infecting F pilus-positive E. coli in the intestinal flora with application via the oral route (Riemer et al 2005).…”

“…Riemer et al (2005) screened a linear 9mer phage display peptide library using the antihigh molecular-weight melanoma-associated antigen (HMW-MAA) monoclonal antibody (mAb) 225.28 S. Fifteen peptides were selected in the biopanning procedure. Biopanning is an affinity selection technique that selects for peptides binding to a given target (Ehrlich et al 2000).…”