MAGE‐A10 is a nuclear protein frequently expressed in high percentages of tumor cells in lung, skin and urothelial malignancies

MAGE‐A10 is a highly immunogenic member of the MAGE‐A family of cancer/testis tumor‐associated antigens (C/T TAAs). Studies performed with broadly reactive antibodies have helped to initially characterize this TAA. However, no specific reagents have been developed so far, thus preventing a thorough analysis of its expression in healthy and tumoral tissues. We have produced MAGE‐A10 gene product in soluble recombinant form, and we have used it to generate specific monoclonal antibodies (mAbs). One of these reagents, recognizing an epitope located at the COOH terminus of the MAGE‐A10 gene product, was used to stain a multitumor tissue microarray comprising more than 2,500 paraffin‐embedded specimens including healthy tissues, benign tumors and malignancies of different histological origin. MAGE‐A10 protein was identified as an intranuclear protein of an apparent molecular weight of 70 kDa, expressed in normal spermatogonia and spermatocytes but in no other healthy tissue. Most importantly, this C/T TAA appears to be expressed in high (>50%) percentages of cancer cells from a number of malignancies, including lung, skin and urothelial tumors. Unexpectedly, high expression of MAGE‐A10 TAA at the protein level was also detectable in gynecological malignancies and stomach and gall bladder cancers. The characterization of MAGE‐A10‐specific reagents might set the stage for the development of targeted active immunotherapy by clarifying potential indications and by allowing the selection of patients eligible for treatment and the monitoring of its effectiveness.