A Phase II Study of Sepantronium Bromide (YM155) Plus Rituximab in Previously Treated Subjects with Aggressive CD20-Positive B Cell Non-Hodgkin's Lymphoma Who Are Ineligible for or Have Previously Received an Autologous Stem Cell Transplant - Stage I Results.

Survivin is responsible for preservation of cell viability and regulation of mitosis in tumor cells. Survivin is overexpressed in the majority of aggressive B-cell lymphomas and thus is an attractive target in subjects with relapsed lymphoma. YM155 is a survivin suppressant that in vitro, when combined with rituximab, synergistically enhances the induction of apoptosis in lymphoma cells. In human DLBCL xenograft models, this combination significantly inhibits tumor growth and prolongs survival. Based on these preclinical combination data and single agent clinical data, a Phase 2 study utilizing YM155 rituximab was initiated.

The study employs a two-stage group sequential method, designed to enroll a total of 40 subjects with an interim futility assessment (Stage I). Eligible patients have histologically confirmed relapsed CD20-positive primary or transformed diffuse large B cell lymphoma (DLBCL) or grade 3 follicular lymphoma (FL) and are either not candidates or previously had an autologous stem cell transplant (ASCT). Subjects had received ≥ 1 prior anthracycline containing regimen with a documented response to the last regimen prior to study entry. Induction, ASCT and maintenance therapy were considered as one regimen. The dosing regimen was YM155 5 mg/m²/day as a 168 hour (7-day) continuous infusion in a 14 day cycle and rituximab 375 mg/m²2 Days 1 and 8 cycles 1 – 4 and then repeated every 10 cycles. The primary endpoint of the study is objective response rate (ORR) per modified IWG 2007. Imaging studies are performed every 8 weeks (4 cycles) after initiation of therapy. In order to continue enrolling in the study, an overall response rate of 4/16 (25%) must be achieved. Results from the completed Stage I are reported here.

Sixteen subjects, the majority of whom were male 13/16 (81%), were enrolled in Stage I. The median age was 62.9 (range: 32 – 78) with a majority of subjects 15/16 (93.8%) with DLBCL. IPI/FLIPI scores were intermediate in 10 subjects (62.5%) and high in 3 subjects (18.8%). The median number of prior therapies was 2 (range: 1 – 5), 16/16 (100%) of patients received rituximab in 1^st or subsequent lines of therapy. Seven patients (43.7%) had prior ASCT. The median number of cycles of YM155 administered was 11 (1–37). The overall response rate was 9/16 (56.3%) with 2/16 (12.5%) CR, 7/16 (43.8%) PR and 4/16 (25%) SD. The median time to response was 53 days (range: 52 – 109). Median duration of response and median PFS has not been achieved. Clinical benefit rate was 13/16 (81.3%). The most common adverse events reported, regardless of relationship, were pyrexia 8/16 (50%), cough 7/16 (43.8%), asthenia 5/16 (31%) and fatigue, back pain, vomiting, neutropenia and thrombocytopenia each 4/16 (25%). Five subjects (31.3%) experience Grade 4 adverse events and 2 (12.5%) had Grade 5 adverse events (disease progression and respiratory failure), neither of which was considered related to therapy. The most common Grade 4 event was neutropenia 4/16 (25%), with all other Grade 4 events occurring in only 1 subject (febrile neutropenia, thrombocytopenia, general physical health deterioration, infusion site extravasation, central line infection, infective thrombosis, mediastinitis, dyspnoea, pleural effusion).

In subjects with relapsed aggressive NHL receiving combination YM155 and rituximab, the ORR for Stage I was 56.3%, which exceeds the requirement to continue to Stage II. Overall the combination regimen was well tolerated with limited hematologic toxicities. Stage II enrollment is ongoing.

Papadopoulos:Astellas: Consultancy, Research Funding. Steinberg:Astellas Pharma: Employment. Papa:Astellas Pharma: Employment. Keating:Astellas Pharma: Employment.