Purpose: Fumagillin and related compounds have potent antiproliferative activity through inhibition of methionine aminopeptidase-2 (MetAP-2). It has recently been reported that MetAP-2 is highly expressed in germinal center B cells and germinal center^derived non^Hodgkin's lymphomas (NHL), suggesting an important role for MetAP-2 in proliferating B cells. Therefore, we determined the importance of MetAP-2 in normal and transformed germinal center B cells by evaluating the effects of MetAP-2 inhibition on the form and function of germinal centers and germinal center^derived NHL cells. Experimental Design: To examine the activity of PPI-2458 on germinal center morphology, spleen sections from cynomolgus monkeys treated with oral PPI-2458 were analyzed. Antiproliferative activity of PPI-2458 was assessed on germinal center^derived NHL lines in culture. A MetAP-2 pharmacodynamic assay was used to determine cellular MetAP-2 inhibition following PPI-2458 treatment. Finally, inhibition of MetAP-2 and proliferation by PPI-2458 was examined in the human SR NHL line in culture and in implanted xenografts. Results: Oral PPI-2458 caused a reduction in germinal center size and number in lymphoid tissues from treated animals. PPI-2458 potently inhibited growth (GI 50 = 0.2-1.9 nmol/L) of several NHL lines in a manner that correlated with MetAP-2 inhibition. Moreover, orally administered PPI-2458 significantly inhibited SR tumor growth, which correlated with inhibition of tumor MetAP-2 (>85% at 100 mg/kg) in mice. Conclusions: These results show the potent antiproliferative activity of PPI-2458 on NHL lines in vitro and oral antitumor activity in vivo and suggest the therapeutic potential of PPI-2458 as a novel agent for treatment of NHL should be evaluated in the clinical setting.Non-Hodgkin's lymphoma (NHL) is the sixth leading cause of cancer death in the United States and has increased in incidence by >80% since 1973 (1, 2). NHL can be divided into at least 29 different subtypes of malignancy of either T-or Blymphocyte origin. The vast majority of NHL malignancies are B cell derived. Moreover, a large number of these B-cell malignancies exhibit phenotypic characteristics consistent with a germinal center origin, the site where B cells undergo proliferation and somatic hypermutation.Germinal center -derived B-cell lymphomas can be divided into at least three groups. Follicular lymphoma is responsible for 22% of all NHLs, and almost always exhibits aberrant expression of the antiapoptotic gene 3,4). Follicular lymphoma typically follows an indolent course but often transforms into the more aggressive diffuse large B-cell lymphoma (DLBCL; ref. 5). Whereas at least half of all DLBCLs express germinal center markers (Bcl-6 + , CD10 + ), the remainder may more closely resemble activated B lymphocytes and potentially deserve a distinct classification (6, 7). Under the current classification, DLBCLs represent 40% of all NHLs (8). A third type of germinal center -derived B-cell neoplasm, Burkitt's lymphoma, is highly aggre...