8502 Background: Survivin is a member of the inhibitor of apoptosis proteins (IAPs) family which is responsible for preservation of cell viability and regulation of mitosis in tumor cells. YM155, a survivin suppressant, has exhibited anti-tumor activity in solid tumors and non-Hodgkins lymphoma (NHL), including DLBCL patients enrolled in Phase I and Phase II monotherapy studies. Methods: Two studies enrolled 43 DLBCL patients; a Phase I study enrolled patients with solid tumors and NHL (n=1 relapsing DLBCL and n=1 refractory DLBCL), and a Phase II study enrolled refractory DLBCL patients (n=41). YM155 was administered at 4.8 mg/m2/day (Phase I) and at 5 mg/m2/day (Phase II) as a 168-hour continuous infusion in a 21 day cycle. Patients could continue to receive YM155 until disease progression or unacceptable toxicity. Results: Data are presented for the first 27 patients (Phase I and Phase II) who have completed therapy. Median age was 61 (23–80) years and 63% were male. Three patients (11%) had partial responses (PR) confirmed by independent review using Cheson criteria (N=2; 1999 criteria and N=1; 2007 updated criteria). All responders received 2 prior regimens. Two responders were refractory to their last regimen and one had relapsed approximately 2 years after stem cell transplant (SCT). One patient responded after 2 cycles, completed 5 total cycles and proceeded to SCT (disease-free > 3.7 years post SCT). A second patient responded after 3 cycles, completed 7 total cycles and proceeded to SCT in OCT08. The third patient responded after 12 cycles and received 26 total cycles (1.5 years) before disease progression. The most common (>4%), treatment-related grade 3/4 adverse events included anemia (16.0%) and neutropenia, fatigue, hemoglobin decrease and deep vein thrombosis (8.0% each). Conclusions: YM155 is well tolerated and has modest single-agent, anti-tumor activity in relapsed/refractory DLBCL patients. Because of single-agent activity and preliminary data showing synergism when YM155 is combined with other agents additional clinical studies are being planned. [Table: see text]