Expression and immune responses to MAGE antigens predict survival in epithelial ovarian cancer

Abstract

The MAGE cancer-testis antigens (CTA) are attractive candidates for immunotherapy. The aim of this study was to determine the frequency of expression, humoral immunity and prognostic significance of MAGE CTA in human epithelial ovarian cancer (EOC). mRNA or protein expression frequencies were determined for MAGE-A1, -A3, -A4, -A10 and -C1 (CT7) in tissue samples obtained from 400 patients with EOC. The presence of autologous antibodies against the MAGE antigens was determined from 285 serum samples. The relationships between MAGE expression, humoral immunity to MAGE antigens, and clinico-pathologic characteristics were studied. The individual frequencies of expression were as follows: A1: 15% (42/281), A3: 36% (131/390), A4: 47% (186/399), A10: 52% (204/395), C1: 16% (42/267). Strong concordant expression was noted with MAGE-A1:-A4, MAGE-A1:-C1 and MAGE-A4:-A10 (p<0.0005). Expression of MAGE-A1 or -A10 antigens resulted in poor progression free survival (PFS) (OR 1.44, CI 1.01-2.04, p = 0.044 and OR 1.3, CI 1.03-1.64, p = 0.03, respectively); whereas, MAGE-C1 expression was associated with improved PFS (OR 0.62, CI 0.42-0.92, p = 0.016). The improved PFS observed for MAGE-C1 expression, was diminished by co-expression of MAGE-A1 or -A10. Spontaneous humoral immunity to the MAGE antigens was present in 9% (27/285) of patients, and this predicted poor overall survival (log-rank test p = 0.0137). These findings indicate that MAGE-A1, MAGE-A4, MAGE-A3, and MAGE-A10 are priority attractive targets for polyvalent immunotherapy in ovarian cancer patients.

Figure 1. A–I: Immunohistochemical staining for MAGE.

Specimens were stained with polyclonal antibody for MAGE-A3 (X20), clones 57b and A3 hybridoma supernatants for MAGE-A4 and MAGE-A10, respectively (x15). Specimens from the normal ovary and testis were used as negative and positive controls, respectively. A–C: Staining of the normal ovary showing no reactivity. D–F: Staining of the testis showing seminiferous tubules with strong intratubular staining, and absent non-specific reactivity. G–I: Staining of ovarian tumor demonstrating strong cytoplasmic and/or nuclear staining patterns.

Figure 2. A–B: Co- expression of MAGE antigens in ovarian cancer.

(A) MAGE-A1 is co-expressed with –A3 or –A4 or –C1. MAGE-A3 is co-expressed with –A10. MAGE-A4 is co-expressed with MAGE-A10. The darker color intensity represents a stronger significance. The strongest associations are between MAGE-A1 to –A4, MAGE-A1 to –C1 and MAGE-A1 to –A3. Odds ratios (OR) greater than 1 imply the antigens tend to appear together. (B) Phylogenetic tree for MAGE expression. Each leaf ending in a pie chart symbolizes a person.

Figure 3. Survival by MAGE expression.

Overall survival curves for patient groups based on MAGE-A10 and –C1 expression. MAGE-C1 expression predicts an improved progression free survival and a trend towards improved overall survival. Expression of MAGE-A10 dampens survival outcomes to the degree of patients with negative MAGE expression.

Figure 4. Survival by MAGE serology.

Overall survival curves for patients groups based on the presence of anti-MAGE autoantibody. Humoral response to any MAGE antigen predicts poor overall survival, and no significant association with progression free survival.