John F. Seymour, Gavin Cull, Geoff Chong, Rodney J. Hicks, Ruth Columbus, Robin Filshie, Mark Hertzberg, Belinda Butcher, Anne-Marie Watson, George Kannourakis, John Taper, Maher K. Gandhi, Stephen Larsen, Devinder Gill, Pauline Warburton, William Renwick, Uwe Hahn, Max Wolf, Judith Trotman, Andrew Wirth, Sam Milliken, Andrew Grigg, Ian D. Lewis, Shir-Jing Ho, and Keith Fay
Introduction: Early ASCT improves progression-free survival (PFS) but not overall survival (OS) in poor prognosis DLBCL treated with R-CHOP immuno-chemotherapy (Stiff P et al., NEJM 2013). Furthermore, indiscriminate ASCT exposes those poor-risk patients destined to remain in CR with R-CHOP alone to unnecessary toxicity. Here, the role of interim PET/CT to risk-stratify is controversial. One confounding factor is that interim PET/CT is typically performed after 2 (or 3) cycles of chemotherapy when FDG-avidity likely reflects a mix of residual cancer cells and inflammation; in contrast, interim PET/CT after cycle 4 may be more representative of resistant lymphoma. We hypothesized that: 1. assessment of DLBCL patients by interim PET/CT after 4 cycles (iPET4) of R-CHOP-14 allows greater specificity of FDG-avidity; and, 2. for patients with iPET4-positivity, early treatment intensification with R-ICE chemotherapy followed by Zevalin-BEAM conditioning and ASCT results in 2-yr PFS that is equivalent to interim-PET/CT-negative patients treated with R-CHOP alone. Methods: We conducted a prospective multicenter phase 2 study which enrolled DLBCL patients ≤ 70 yrs with either IPI=2-5, or IPI =0-1 with tumor bulk (≥ 7.5 cm), and who were considered fit for ASCT. All patients underwent a diagnostic PET/CT at study entry and were planned to receive 4 cycles of R-CHOP-14 and supported with Pegfilgrastim. Cycle 5 of R-CHOP-14 was delayed 7 days, and an interim PET/CT scan was undertaken at d17-d20 post-4th R-CHOP-14, the delay intended to reduce the impact of rebound inflammation after R-CHOP. All interim PET/CT scans were assessed centrally by a core group of imaging specialists using International Harmonization Project (IHP) criteria with mediastinal blood pool as the reference. Biopsy to confirm residual tumor was not mandated. iPET4-positive patients received 3 cycles of R-ICE followed by ASCT with Zevalin-BEAM conditioning; those who were iPET4-negative received a further 2 cycles of R-CHOP-14 plus 2 doses of Rituximab. Results: A total of 162 patients were enrolled from 20 Australian centers; 11 patients were excluded because of failure to meet inclusion criteria. Baseline characteristics of the 151 evaluable patients included: median age 57 yrs (range, 21 to 69), 40% aged > 60 yrs, 62% males, 79% stages 3 or 4, 13% ECOG PS > 1, 78% elevated LDH, 48% extranodal sites > 1, 54% bulky disease ≥ 7.5 cm, 20% IPI=0-1, 27% IPI=2, 31% IPI=3, and 23% IPI=4-5. No interim PET/CT scan was performed in 8 patients due to progressive disease (PD) (1), bowel perforation (2), toxicity (3), and dose delays ≥ 2 weeks (2). Interim PET/CT scans were undertaken at d17-d20 in 62% and d14-d16 in another 23%. Of the 143 patients with interim PET/CT, 101 (71%) were deemed iPET4-negative and 42 (29%) were iPET4-positive. Interestingly, the baseline characteristics were comparable between iPET4-negative and iPET4-positive patients. Of the 101 iPET4-negative patients, 5 failed to complete therapy due to PD (3), toxicity (1), or infection (1). Of the 42 iPET4-positive patients, 10 failed to complete intensification therapy due to PD (6), 2nd malignancy (1), or consent withdrawal (3). Among iPET4-positive patients undergoing ASCT, there was 1 treatment-related death due to viral infection. At a median follow-up of 35 months, the Kaplan-Meier (KM) estimate of 2-yr PFS and OS for the entire eligible cohort of 151 pts was 72% and 85%, respectively. For the 101 iPET4-negative and 42 iPET4-positive patients, 2-yr PFS was 74% and 67% (P =0.32) (Figure 1), and 2-yr OS was 88% and 78% (P=0.11) (Figure 2), respectively. Among iPET4-negative and iPET4-positive patients with IPI=3-5, 2-yr PFS was 65% and 69% (P=0.74), and 2-yr OS was 81% and 83% (P =0.85), respectively. Conclusions: Patients with poor risk DLBCL who are interim PET/CT-positive after 4 cycles of R-CHOP-14 and switched to intensification with R-ICE followed by ASCT with Zevalin-BEAM have favorable rates of PFS and OS that are equivalent to that seen for patients who are interim PET/CT-negative. This study supports further investigation of treatment intensification in patients with poor risk DLBCL who are interim PET/CT-positive after 4 cycles of immuno-chemotherapy. The study was supported in part by Roche Products Pty. Ltd, Amgen Australia Pty. Ltd, and Bayer Australia Ltd. Figure 1. Progression Free Survival by Interim PET/CT Figure 1. Progression Free Survival by Interim PET/CT Figure 2. Overall survival by Interim PET/CT Figure 2. Overall survival by Interim PET/CT Disclosures Hertzberg: Janssen-Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda Oncology: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees. Gill:AbbVie: Honoraria; Roche: Research Funding; Sanofi Aventis: Research Funding; Roche: Honoraria. Ho:Celgene: Other: Travel. Cull:Janssen-Cilag: Membership on an entity's Board of Directors or advisory committees; Amgen: Other: Travel. Grigg:Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees; Merck: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees. Lewis:Amgen: Other: Travel; Roche: Honoraria, Other: Travel. Renwick:Amgen: Other: Travel; Bayer: Speakers Bureau. Seymour:Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Speakers Bureau; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech, Inc.: Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees; Infinity: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Research Funding, Speakers Bureau; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Research Funding; Phebra: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees.