Prognostic Impact of Cancer Testis Antigens Expression in Advanced Stage Multiple Myeloma Patients.

Background: Cancer testis antigens have become the most extensively studied antigen group in the field of tumor immunology.

Aims: This study aims to analyze global expression of 14 CT (cancer/testis) antigens in MM to identify possible prognostic markers and therapeutic targets.

Patients and Methods: The expression of MAGEA1, MAGEA2, MAGEA3/6, MAGEA4, MAGEA10, MAGEA12, BAGE1, MAGEC1/CT7, GAGE family, LAGE-1, PRAME, NY-ESO-1, SPA17 and SSX1 was studied by RT-PCR in: 15 normal tissues, one pool of 10 normal bone marrow samples, three normal tonsils and bone marrow aspirates from six normal donors, three monoclonal gammophaties of undetermined significance (MGUS), five solitary plasmacytomas, 39 MM samples (95% advanced stage) and MM cell line U266. CodeLink Human UniSet I Bioarrays 10,000 genes was used for arrays analyses.

Results: SPA17 was positive in all normal tissues and was excluded for further analyses. MAGEC1/CT7 was positive in bone marrow aspirates from one MGUS and in one plasmacytoma. U266 cell line was positive for all CT antigens, except SSX1. The frequencies of CT antigens expression in MM patients were: MAGEC1/CT7 = 30/39 (77%); LAGE-1 = 19/39 (49%); MAGEA3/6 = 16/39 (41%); MAGEA2 = 14/39 (36%); GAGE family = 13/39 (33%); NY-ESO-1 = 13/39 (33%); BAGE-1 = 12/39 (28%); MAGEA1 = 10/39 (26%); PRAME = 9/39 (23%); SSX-1 = 10/39 (26%); MAGEA12 = 8/39 (20.5%); MAGEA4 and MAGEA10 = 0%. Cox’s regression model showed that GAGE family positivity and number of positive CT antigens > 6 were independent prognostic factors when all patients were analyzed. However, MAGEC1/CT7 expression was the only independent prognostic factor when non-transplanted patients where analyzed. Three samples predominantly positive (> 6) and three samples predominantly negative (0 or 1) for the 13 analyzed CT antigens were submitted to microarrays analyses. 147 genes were overexpressed in predominantly positive CT antigens samples.

Conclusions: Based on our findings, MAGEC1/CT7, MAGEA3/6 and LAGE-1 seem good candidates for immunotherapy, since together they are overexpressed in 85% of our MM cases. Besides, GAGE family expression, number of CT antigens > 6 and MAGEC1/CT7 seem to have impact on MM prognosis. Also, the results of arrays analyses corroborate the hypothesis that MM can be separate in two groups: predominantly positive and predominantly negative for CT antigens, meaning that these antigens may have important role for MM biology.