Human High Molecular Weight Melanoma-Associated Antigen Mimicry by Mouse Anti-Idiotypic Monoclonal Antibody MK2-23: Enhancement of Immunogenicity of Anti-Idiotypic Monoclonal Antibody MK2-23 by Fusion with Interleukin 2

Abstract

To overcome unresponsiveness to the self-high molecular weight melanoma-associated antigen (HMW-MAA) in hosts with constitutive HMW-MAA expression, we have used as immunogen the anti-idiotypic monoclonal antibody (mAb) MK2-23, which mimics the antigenic determinant recognized by the anti-HMW-MAA mAb 763.74. In a phase I/II clinical trial, anti-idiotypic mAb MK2-23, conjugated to keyhole limpet hemocyanin (KLH) as a carrier and given with Bacillus Calmette-Guerin (BCG) as an adjuvant, elicited HMW-MAAspecific antibodies in about 60% of the immunized melanoma patients. The immune response was associated with survival prolongation. However, safety and standardization issues associated with the use of KLH and BCG in the clinical setting have prompted us to develop alternative immunization strategies. Conjugation of human interleukin 2 (IL-2) to mAb MK2-23 variable regions covalently linked to human immunoglobulin constant regions enhanced mAb MK2-23 immunogenicity in BALB/c mice to an extent similar to that induced by mAb MK2-23 conjugated to KLH and given with Freund's adjuvant. As determined by the level of serum antibodies and delayed-type hypersensitivity responses to HMW-MAAbearing melanoma cells, immunization of mice with the MK2-23-IL-2 fusion protein elicited more robust humoral and cellular responses, respectively, than immunization with KLH-conjugated mAb MK2-23 and separate administration of IL-2. The immunogenicity of the fusion protein is dependent on IL-2 conjugation, because immunization of mice with either mAb MK2-23 or chimeric mAb MK2-23, in combination with IL-2, was not as effective in eliciting HMW-MAA-specific immune responses. These results suggest that the MK2-23-IL-2 fusion protein represents a useful immunogen to implement active specific immunotherapy in patients with melanoma, because it bypasses the requirement for KLH conjugation and adjuvant administration. (Cancer Res 2005; 65(15): 6976-83)

CSPG4: a prototype oncoantigen for translational immunotherapy studies

“…Interestingly, the induction of CSPG4-specific antibodies in immunized patients was associated with significantly longer survival and metastasis regression [104, 105]. However, this approach never ended up in clinics, due to both the difficulties in standardization of MK2-23 (it has to be conjugated to keyhole limpet hemocyanin as a carrier) and to side effects associated with Bacille Calmette–Guerin administration required to induce an efficient immune response [106]. 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].…”

“…However, this approach never ended up in clinics, due to both the difficulties in standardization of MK2-23 (it has to be conjugated to keyhole limpet hemocyanin as a carrier) and to side effects associated with Bacille Calmette–Guerin administration required to induce an efficient immune response [106]. 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].…”

Recapitulation of the anti-Idiotype antibodies as vaccine candidate

“…In melanoma patients' antitumor antibody response can be elicited by the injecting 2 mg of anti-Id mAb MK2-23, that acts as an exact duplication of a high molecular weight human melanoma antigen. Further, the effect of Ids has been analyzed on tumor growth [47]. Usually, there are more questions when immunoglobulins are widely-used as curative agents that encompass the production of high antibody response, in particular when murine anti-ids Ab is used [48].…”

Anti-idiotypic antibodies as cancer vaccines: achievements and future improvements

“…Even though this was a retrospective study, a multivariate analysis showed that the development of anti-HMW-MAA antibodies was the most important variable for predicting survival. Wang et al (2005) demonstrated that MK2-23 (mimic HMW-MAA)-IL-2 fusion protein is useful to implement active specific immunotherapy in patients with melanoma, because it bypasses the requirement for KLH conjugation and adjuvant administration.…”