Detection of circulating lymphoma cells in patients with non-Hodgkin lymphoma using MAGE-A3 gene expression in peripheral blood.

BACKGROUND/AIMS: Lymphoma-specific gene expression in peripheral blood reflects the presence of circulating lymphoma cells (CLCs). MAGE-A3 is widely expressed in solid tumors and is a potent candidate for immunotherapy. To determine whether MAGE-A3 expression would be a useful marker for CLCs in non-Hodgkin lymphoma (NHL), we assessed MAGE-A3 mRNA expression in the peripheral blood of NHL patients and controls.

METHODS

We measured MAGE-A3 gene expression in ten lymphoma cell lines (Farage, RL, SU-DHL, Toledo, WSU-NHL, BJA-B, Daudi, Raji, Granta-519 and Jurkat) using nested RT-PCR, and determined detection sensitivity using mixtures of MAGE-A3-positive and -negative cells over a range of 1/10(6) to 10(6)/10(6) cells. MAGE-A3 expression was determined in buffy coat samples of 40 controls and 95 NHL patients prior to treatment. Clinical characteristics (e.g., cell lineage) and international prognostic indices, including age, performance, LDH, stage and extra-nodal involvement, were evaluated and related to MAGE-A3 expression. Hazard ratios, reflecting risk for overall survival and progression-free survival, were also evaluated. Follow-up MAGE-A3 expression was evaluated at two time points: after 3-4 cycles of chemotherapy (80 patients) and after 6-8 cycles of chemotherapy (74 patients).

RESULTS

MAGE-A3 mRNA was detected in four lymphoma cell lines - RL, Farage, Toledo and Raji - and was present in 45 of 95 (47.3%) patients with NHL, but in none of the 40 controls. The detection sensitivity was 1 in 1000 cells. MAGE-A3 expression prior to treatment was not associated with clinical features or patient survival. During follow-up, only six patients (7.5%) were positive for MAGE-A3 after 3-4 cycles of chemotherapy and three (4.1%) were positive after 6-8 cycles.

CONCLUSIONS

The results showed that MAGE-A3 gene expression was frequent in NHL patients and decreased after effective chemotherapy, suggesting that MAGE-A3 can be used as a tumor marker for CLCs in patients with NHL. However, MAGE-A3 expression showed no prognostic value in this group of patients.