Neither Germinal Center (GC) vs Non-Germinal Center (Non-GC) Phenotype nor FOXP1 Expression Correlate with Outcome in AIDS-Associated Diffuse Large B-Cell Lymphoma (DLBCL): Study of Patients from AIDS Malignancies Consortium Trials 010 and 034.

Background: Germinal center (GC) and non-germinal center (non-GC) gene expression profiles correlate with survival in immunocompetent DLBCL patients. Phenotypic expression patterns of CD10, BCL6, MUM1 and CD138 are surrogates for genetic studies with comparable survival data; CD10+, BCL6+/−, MUM1- defines GC while CD10-, BCL6-, MUM1+/− identifies the non-GC phenotype with poorer prognosis. Expression of FOXP1, a transcription factor differentially expressed in resting and activated B cells, and PRDM1/BLIMP1, a regulator of terminal B cell differentiation, are also adverse prognostic markers for DLBCL in immunocompetent patients. AIDS-associated DLBCLs from uniformly treated HIV+ patients in AMC010 (CHOP vs. CHOP-rituxan) and AMC034 (EPOCH vs. EPOCH-rituxan) were examined to determine if the GC vs. non-GC phenotype, FOXP1 expression and/or BLIMP1 expression are prognostic in this patient population.

Design: Slides of 32 and 30 AIDS-associated DLBCLs from AMC010 (closed) and AMC034 (in analysis) patients, respectively, were available for FOXP1, BLIMP1, CD10, BCL6, MUM1, BCL2, Ki-67 immunohistochemistry and in situ hybridization for EBV (EBER). Antigen expression by >20% tumor cells (>10% for BLIMP1) was considered positive. GC phenotype was defined as CD10+, BCL6+/−, MUM1- while the non-GC cases were CD10-, BCL6-, MUM1+/−. Overall survival (OS) based on GC vs. non-GC phenotype was examined. FOXP1 expression was correlated with survival; BCL2, Ki-67 expression; and EBV status; BLIMP1 expression was correlated with survival in a subgroup of patients from AMC 034.

Results: Of the 62 cases, 59% were MUM1, 60% BCL6, 53% CD10, 59% BCL2, 49% FOXP1, 67% BLIMP1 and 30% EBER positive. 19 (58%) cases were classified as GC and 14 as non-GC. No mean OS difference between GC and non-GC groups (p=0.74) or FOXP1+ and FOXP1- cases (p=0.8; t-test) in the AMC 010 patients; BLIMP1 expression did not correlate with survival in the subgroup of AMC 034 patients (p=0.4). GC vs. non-GC phenotype did not correlate with FOXP1 expression (p=0.1) or BLIMP1 expression (p=0.4). In addition, FOXP1 expression did not correlate with EBV positivity, BCL2, MUM1, BCL6 or CD10 expression or proliferation rate based on Ki67 (chi-square).

Conclusions: AIDS-associated DLBCLs can be classified as GC and non-GC cases, but this classification does not appear to correlate with prognosis/OS in uniformly treated HIV-positive patients. Furthermore, in contrast with immunocompetent DLBCLs, FOXP1 expression also does not correlate with OS in this patient population; similarly BLIMP1 expression also does not correlate with survival in the HIV+ patient population. In addition, GC vs non-GC phenotype did not correlate with FOXP1 or BLIMP1 expression, while FOXP1 expression did not correlate with prognostic markers BCL2/Ki67 or EBV status. Thus, prognostic markers useful in immunocompetent patients with DLBCL may not be relevant for HIV positive patients, suggesting that patient immune status rather than tumor biology may be more important in predicting patient outcome.