PIK3CA, BCL-6, MLL and FOXP1 in the transformation and prognosis of MALT lymphoma.

8577 Background: Recent study showed that the most common gene abnomalities in gastrointestinal MALT lymphoma included 3q26.2 -27,11q23-24 amplifications and t(3;14) (p14.1;q32). MALT lymphoma shared the same aberrations with DLBCL but with a lower rate, suggesting a clonal transformation from low to high-grade lymphoma. Four important oncogenes were found to be involved in these aberrations, including PIK3CA, BCL-6, MLL and FOXP1. Rare studies about the role of expression of 4 oncogenes in the transformation and prognosis of MALT lymphoma were seen.,We conducted this research to explore the expression of PIK3CA, BCL-6, MLL and FOXP1 in 40 gastrointestinal MALT lymphoma cases that were classified to large-cell (involving 5%-20% large cells in the specimen) or non- large cell (involving <5% large cells) pathologic subtype and 10 transformed gastrointestinal DLBCL specimens (involving >20% large cells with residual small-cell components) through immunohistochemistry staining. Prognostic significance of 4 indexes was also analyzed.,In 40 gastrointestinal MALT lymphoma cases, large-cell subtype were found in 7 (17.5%). The percentage of positive expression of PIK3CA, BCL-6, MLL and FOXP1 in non-large cell subtype was 42.4%, 15.2%, 66.7% and 12.0%, while in large-cell subtype the percentage was 42.9%, 28.6%, 100% and 28.0%, respectively. Among non-large cell subtype, large-cell subtype of MALT lymphoma and transformed DLBCL, only the rate of FOXP1 expression (>75% positive staining cells) was raised up in order (12.0%, 28.0% and 40%, P=0.046). PIK3CA expression (18/40) was an independent negative prognostic variable on the PFS (P=0.008) .The positive expression of BCL-6, MLL and FOXP1 did not show any significant prognostic value.,Our data suggests that PIK3CA, a novel molecular index, can predict a worse prognosis in gastrointestinal MALT lymphoma. The study also provides some clues to further genetic research that will finally demonstrate the role of FOXP1 in the transformation from MALT lymphoma to DLBCL. No significant financial relationships to disclose.