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Introduction Midostaurin is the only approved FLT3 inhibitor for combination with intensive induction and consolidation chemotherapy in newly diagnosed patients with FLT3 mutant AML. The FLT3 inhibitor, sorafenib, was investigated in the randomized SORAML trial (Röllig, Lancet Onc 2015), in combination with intensive chemotherapy (IC) for newly diagnosed adults with AML Methods The Australasian Leukaemia and Lymphoma Group (ALLG) conducted a randomized phase 2 study [ACTRN12611001112954] in 99 adults aged 18-65 years with newly diagnosed FLT3-ITD positive (allelic ratio (AR) ≥0.05) AML to determine whether addition of SOR to IC would improve event-free survival (EFS). The study was powered to identify a 25% increase in 2-year EFS with SOR. Patients 18-55 yrs received induction with IDAC-3 (idarubicin [IDA] 12 mg/m2 D1-3 and ara-C 1.5 g/m2 BD D1,3,5,7); patients 56-65 received 7+3 (IDA 12 mg/m2 D1-3 and ara-C 100 mg/m2 D1-7 IVI). Patients were randomized 2:1 to SOR or PBO 400 mg BD on days 4-10 of induction and each consolidation cycle. Due to the pharmacokinetic interaction between SOR and azoles, antifungal prophylaxis during induction was with AmBisome 5 mg/kg IV twice weekly. For consolidation, patients 18-55 yrs received 2 cycles of IcE (IDA 9 mg/m2 D1-2, ara-C 100 mg/m2 D1-5 IVI and etoposide 75 mg/m2 D1-5), those 56-65 yrs received 2 cycles of IDAC-2 (IDA 12 mg/m2 D1-2 and ara-C 1g/m2 BD D1,3,5). Maintenance was with SOR/PBO 400 mg bd days 1-28 for 12 cycles. Allogeneic HCT (allo-HCT) was at investigator discretion. SOR/PBO was not continued post allo-HCT. The primary endpoint was EFS without censoring for allo-HCT with events defined as failure to achieve complete remission (CR) or CR with incomplete hematologic recovery (CRi), relapse or death. Pre-specified secondary endpoints included overall response rate (ORR) defined as CR and CRi, tolerability, EFS according to FLT3-ITD AR < or ≥ 0.7 and impact of randomization on allograft outcome. Results Between Jan 2013-May 2018, 18 centers randomized 99 patients to induction with either SOR (n=65) or PBO (n=33); one patient later found to be FLT3-ITD negative was excluded. Patient characteristics are shown in Table 1. Treatment arms were balanced apart from fewer patients in the SOR arm with NPM1 mutant AML. Deliverability of therapy was comparable, with commencement of consolidation in 78% and 79% and maintenance therapy in 32% and 27% in the SOR and PBO arms, respectively. The overall response rate (ORR) was high in both arms; 91% in the SOR (CR 80%, CRi 11%) and 94% in the PBO (CR 70%, CRi 24%) arm. In the SOR arm, 5% achieved partial remission, went off study and were deemed treatment failures. With a median overall follow-up of 25 mo, there was no significant difference in EFS (HR 0.87 95% CI 0.50-1.49; P=0.61)(Fig A) or OS (HR 0.70 95% CI 0.38-1.29; P=0.26)(Fig. B), nor in a sensitivity analysis with censoring at HCT. 2 yr EFS was 47.9% (SOR) vs 45.4% (PBO) and 2-year OS 66.8% (SOR) vs 56.4% (PBO). Hematopoietic cell transplant (HCT) in CR1 was performed in 62% and 58% in the SOR and PBO arms, respectively. For patients in CR1, 2 yr OS post-HCT was 78.5% (SOR) vs 54.2% (PBO)(Fig C). Suggestive of an on-target effect against FLT3-ITD, the impact of SOR on OS appeared greater for patients with higher FLT3-ITD AR ≥0.7 (Fig. D) (Table 2). Only one early death (within 30 days) was recorded in each treatment arm. The frequency of grade 3-4 adverse events (AEs) were similar between the two arms, apart from palmar-plantar rash, reported as drug-related in 15.4% and 6.1% pts in the SOR and PBO arms, respectively. Correlative studies will be reported in a companion abstract. Conclusions SOR did not improve EFS when combined with intensive chemotherapy in adults with newly diagnosed FLT3-ITD AML. Although not powered for significance, SOR showed a trend for improved OS among patients with higher FLT3-ITD AR or receiving HCT in CR1. Further exploration of more potent FLT3 inhibitors in the pre- and post-allograft setting are warranted for patients with newly diagnosed FLT3 mutant AML. Acknowledgements: The ALLG AMLM16 trial was funded through an Australian Government NHMRC grant and a research grant from the Leukaemia Foundation of Australia. Bayer supplied sorafenib and Gilead AmBisome. Disclosures Wei: Roche: Honoraria; Servier: Consultancy, Honoraria, Research Funding; Novartis: Honoraria, Research Funding, Speakers Bureau; Amgen: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding, Speakers Bureau; Pfizer: Honoraria; Bristol Myers Squibb: Honoraria, Research Funding, Speakers Bureau; Walter and Eliza Hall Institute of Medical Research: Patents & Royalties: AW is eligible for royalty payments related to venetoclax; Astra Zeneca: Honoraria, Research Funding; Janssen: Honoraria; Macrogenics: Honoraria. Enjeti:Novartis: Membership on an entity's Board of Directors or advisory committees; Alexion: Speakers Bureau; Bayer: Speakers Bureau; Sanofi: Speakers Bureau; AbbVie: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees. D'Rozario:Abbvie: Membership on an entity's Board of Directors or advisory committees; BMS/ Celgene: Membership on an entity's Board of Directors or advisory committees. Marlton:Celgene: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees; F. Hoffmann-La Roche Ltd: Membership on an entity's Board of Directors or advisory committees; Astra-Zeneca: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Verner:Janssen Cilag Pty Ltd.: Research Funding. Hahn:Roche: Honoraria; Astra Zeneca: Honoraria. Hiwase:Novartis Australia: Research Funding. Anstee:Walter and Eliza Hall Institute: Patents & Royalties: milestone and royalty payments related to venetoclax.. Levis:FujiFilm: Honoraria, Research Funding; Amgen: Honoraria; Daiichi-Sankyo: Honoraria; Menarini: Honoraria; Astellas: Honoraria, Research Funding. Bajel:Abbvie: Honoraria; Astellas: Honoraria; Pfizer: Honoraria; Amgen: Honoraria, Speakers Bureau; Novartis: Honoraria. Roberts:Genentech: Patents & Royalties: for venetoclax to one of my employers (Walter & Eliza Hall Institute); I receive a share of these royalties; Janssen: Research Funding; Servier: Research Funding; AbbVie: Research Funding. OffLabel Disclosure: Sorafenib for FLT3-ITD AML

Background: Philadelphia chromosome-positive (Ph+) CML is a myeloproliferative disease characterized by the presence of the abnormal Ph+ in hematopoietic cells. Imatinib, dasatinib and nilotinib are BCR-ABL TKIs commonly used in the treatment of CML-CP. Many patients on BCR-ABL TKI therapy will experience adverse events (AEs). Some of the more common AEs associated with first- and second-generation BCR-ABL TKIs include fluid retention, diarrhea, rash, musculoskeletal pain, nausea, vomiting, muscle cramps, and headache. Some patients will be unable to tolerate these AEs and will discontinue therapy. The current study aimed to assess the efficacy and safety of nilotinib in patients with CML-CP who are responsive to but intolerant of treatment with imatinib or dasatinib. Although the study was stopped early due to low recruitment, here we present results on cross-intolerance and molecular response in the patients who were switched from imatinib or dasatinib to nilotinib. Methods: Eligible adult patients had: Ph+ CML-CP associated with BCR-ABL quantifiable by real-time quantitative reverse transcriptase-polymerase chain reaction (RQ-PCR); received ≥3 months imatinib or dasatinib or both; were Results: The study was stopped early due to low recruitment; 20 patients were enrolled (mean age 53.9 years [range 31-77]; 14 female). 16 patients had received prior imatinib therapy, 4 patients prior dasatinib. Median nilotinib treatment duration was 494 days (mean 480, SD 167.6 days). At screening, 30% of patients were not in MMR, 45% had MMR and 25% had MR4.0. By month 3 and 24 of nilotinib treatment, 55% (11/20) and 65% (13/20) of patients, respectively, achieved at least a 1 log reduction in BCR-ABL levels. 35% (7/20) of patients achieved MR4.5 between baseline and month 3 of nilotinib treatment, and 50% (10/20) achieved MR4.5 at any time up to month 24. The proportion of patients with a molecular response at each visit up to month 15 is shown in the Figure. AEs during prior treatment with imatinib and dasatinib included gastrointestinal events (nausea, vomiting, diarrhea), superficial edema, myalgia, fatigue, rash, and headache, among others. 68% of AEs had resolved by month 3 of nilotinib treatment. Among the 13 evaluable patients on prior imatinib, 7 (54%) had resolution of all AEs during treatment with nilotinib; of 3 evaluable patients on prior dasatinib, 3 (100%) had AE resolution on nilotinib. Grade 3/4 AEs during nilotinib therapy occurred in 3 patients: diabetes mellitus, fatigue, neutropenia, pneumonia, osteoarthritis, and hyperuricemia. Conclusions: Although early termination of the study has not allowed for a robust analysis, these results suggest that nilotinib is effective and well tolerated in most patients intolerant of imatinib or dasatinib. During the first 3 months of switching to nilotinib, 55% of patients had achieved at least a 1 log reduction in BCR-ABL levels, and 35% of patients had achieved MR4.5. The cumulative rate of MR4.5 by 24 months was 50%. Achievement of this endpoint has been linked to favorable long-term outcomes, such as treatment-free remission. Furthermore, the majority of the AEs had resolved by month 3 of nilotinib therapy. This improved tolerance to nilotinib may result in improved treatment adherence. As such, although further study in a larger population is needed for confirmation, these results provide further evidence that nilotinib is a favorable option to establish a molecular response in patients intolerant of imatinib or dasatinib. Disclosures D'Rozario: BMS: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Roche: Consultancy, Honoraria. Branford:Qiagen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Research Funding; Ariad: Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Cepheid: Consultancy. Yeung:Ariad: Research Funding; Novartis Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Anderson:Novartis Pharmaceuticals: Employment. Gervasio:Novartis Pharmaceuticals: Employment. Hughes:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Ariad: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

The TIDEL-II trial used imatinib (IM) upfront in patients (pts) newly diagnosed with chronic myeloid leukaemia in chronic phase (CML-CP), and switched selected pts to nilotinib (NIL) on the basis of IM intolerance or failure to achieve time-dependent molecular response. We previously reported major molecular response (MMR; BCR-ABL ≤0.1% IS) at 12 months (mths) and transformation-free survival (TFS) at 3 years. This abstract reports the final analysis with minimum follow-up of 60 months. Patients were enrolled across 27 Australasian sites in 2 equal and sequential cohorts. All started treatment with IM 600mg OD and dose escalated to IM 800mg OD if IM trough levels were The study enrolled 210 pts with a median age of 49.7 years (range 16-81); 42% were female. Baseline demographics and outcomes were similar across 2 cohorts. Forty pts had day 22 IM trough At 60 mths, 75 (36%) pts had withdrawn from study, and 14 were lost to follow up (including 12 with outstanding data queries). Of the 121 pts (58%) who remained on TIDEL-II until 60 mths, 33 were on NIL (30 in MMR), 77 on IM (76 in MMR); treatment was unknown for 11 (10 in MMR). The median dose of IM was 600mg OD. Of the 51 pts who dose escalated to IM 800mg OD (31 for low IM trough level and 20 for failing to achieve molecular targets), only 9 remained on this dose until mth 60 (5 and 4 pts form the respective groups). Eight pts transformed to accelerated or blastic phase; 5 within the 1st year, 2 in the 3rd and 1 in the 5th year; 2/8 occurred after study withdrawal. There were 14 deaths, mostly due to cardiac events (n=5) or progressive leukaemia (n=6). In all, 13/210 pts (6%) had cardiac, cerebral or peripheral vascular disease, 9 while on NIL and 4 having only had IM. Pts failing to meet molecular targets (analysed according to the 1st target failed) at 3, 6 and 12 mths numbered 25 (12%), 23 (11%) and 30 (14%) respectively with 19, 16 and 20 switching to NIL (subsequent molecular outcomes, Table 2). Pts failing to achieve EMR had poor achievement of MMR and MR4.5 (44% and 8% respectively by 60 mths). Of the 11 EMR failure pts who achieved MMR, only 4 remained in MMR at 60 mths. Pts failing to achieve BCR-ABL≤ 1% at 6 mths had similarly poor outcomes, with MMR and MR4.5 being 52% and 13% respectively. In pts failing to achieve MMR by 12 months, MMR and MR4.5 by 60 mths were 93% and 33% respectively. Twenty pts switched to NIL for IM intolerance prior to 24 mths: 9/20 already in MMR, and 3/20 already in MR4.5 at time of switching. For the remaining pts, MMR and MR4.5 were achieved by 100% and 88% after switching. The TIDEL-II strategy of combining IM and NIL compares favourably with other upfront treatment strategies, with MR4.5 of 59% by 60 mths. IM dose escalation to 800mg OD for target failure was not well tolerated: only 18% of pts who dose escalated maintained this dose at 60 mths. However, this did not appear to be detrimental to overall outcomes, which were similar in the 2 cohorts. Pts switching to NIL for IM intolerance, and for failing to achieve MMR by 12 months after meeting prior goals, had high rates of MMR, superior to those who failed their 3 and 6 mth targets. Early identification of pts at high risk of EMR failure who might benefit from more intensive or experimental therapies may be necessary to further improve outcomes. Disclosures Yeung: Novartis Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Ariad: Research Funding. White:Novartis Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Ariad: Consultancy, Honoraria, Research Funding. Branford:Novartis: Honoraria, Research Funding, Speakers Bureau; Qiagen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Otsuka: Research Funding; Ariad: Research Funding; Bristol Myers-Squibb: Honoraria; Cepheid: Consultancy. Butcher:Janssen: Consultancy; Roche: Consultancy; Novartis: Consultancy. Gottlieb:Abbvie: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; Indee: Membership on an entity's Board of Directors or advisory committees. Arthur:Novartis: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees. Ross:Novartis Pharmaceuticals: Honoraria, Research Funding; BMS: Honoraria. Tam:Novartis: Honoraria. Mills:Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Meeting attendance sponsorship. Hughes:Novartis Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Australasian Leukaemia and Lymphoma Group (ALLG): Other: Chair of the CML/MPN Disease Group; Ariad: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Background: Anthracylines are one of the major classes of drugs active against acute myeloid leukemia (AML). Increased doses of daunorubicin during induction therapy for AML have been shown to improve remission rates and survival. The ALLG used idarubicin in induction therapy at a dose of 9 mg/m2 x 3 days (total dose 27 mg/m2) in combination with high-dose cytarabine and etoposide (Blood 2005, 105:481), but showed that a total idarubicin dose of 36 mg/m2 was too toxic in this context (Leukemia 2001, 15:1331). In order to further improve outcomes in adult AML by anthracycline dose escalation, we conducted a phase 3 trial comparing standard to an increased idarubicin dose during consolidation therapy. Methods: Patients achieving complete remission after 1 or 2 cycles of intensive induction therapy (idarubicin 9 mg/m2 daily x3, cytarabine 3 g/m2 twice daily on days 1,3,5 and 7, and etoposide 75 mg/m2 daily x7; ICE protocol) were randomized to receive 2 cycles of consolidation therapy with cytarabine 100 mg/m2 per day for 5 days, etoposide 75 mg/m2 for 5 days, and idarubicin 9mg/m2 daily for either 2 or 3 days (standard and intensive arms respectively). No further protocol therapy was given. The primary endpoint was leukemia-free survival from randomization to consolidation therapy (LFS) with overall survival (OS) as secondary endpoint. Results: A total of 422 patients with AML (excluding cases with CBF rearrangements or APL) aged 16 to 60 years were enrolled between 2003-10, with 345 (82%) achieving complete remission, and 293 being randomized to standard (n=146) or intensive (n=147) consolidation arms. The median age was 45 years in both arms (range 16- 60), and both groups were balanced for intermediate versus unfavorable karyotypes and for frequency of mutations involving FLT3-ITD and NPM1 genes. Of the randomized patients, 120 in the standard arm (82%) and 95 in the intensive arm (65%) received the second consolidation cycle (p Conclusion: We conclude that in adult patients in complete remission after intensive induction chemotherapy an increased dose of idarubicin delivered during consolidation therapy results in improved LFS, without increased non-hematologic toxicity. Figure 1. Figure 1. Disclosures Szer: Ra Pharma: Honoraria, Membership on an entity's Board of Directors or advisory committees; Alexion Pharmaceuticals, Inc.: Honoraria, Membership on an entity's Board of Directors or advisory committees; Alnylam: Honoraria, Membership on an entity's Board of Directors or advisory committees. Marlton:Amgen: 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; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: 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. Wei:Novartis: Consultancy, Honoraria, Research Funding; Roche: Consultancy, Honoraria; CTI: Consultancy, Honoraria; Abbvie: Honoraria, Research Funding; Servier: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding. Cartwright:ROCHE: Consultancy, Membership on an entity's Board of Directors or advisory committees. Roberts:Servier: Research Funding; Janssen: Research Funding; Genentech: Research Funding; AbbVie: Research Funding. Mills:Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Meeting attendance sponsorship. Gill:Janssen: Membership on an entity's Board of Directors or advisory committees. Seymour:Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Genentech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Speakers Bureau; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Research Funding, Speakers Bureau; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees.

The treatment of acute promyelocytic leukemia has improved considerably after recognition of the effectiveness of all-trans-retinoic acid (ATRA), anthracycline-based chemotherapy, and arsenic trioxide (ATO). Here we report the use of all 3 agents in combination in an APML4 phase 2 protocol. For induction, ATO was superimposed on an ATRA and idarubicin backbone, with scheduling designed to exploit antileukemic synergy while minimizing cardiotoxicity and the severity of differentiation syndrome. Consolidation comprised 2 cycles of ATRA and ATO without chemotherapy, followed by 2 years of maintenance with ATRA, oral methotrexate, and 6-mercaptopurine. Of 124 evaluable patients, there were 4 (3.2%) early deaths, 118 (95%) hematologic complete remissions, and all 112 patients who commenced consolidation attained molecular complete remission. The 2-year rate for freedom from relapse is 97.5%, failure-free survival 88.1%, and overall survival 93.2%. These outcomes were not influenced by FLT3 mutation status, whereas failure-free survival was correlated with Sanz risk stratification (P[trend] = .03). Compared with our previously reported ATRA/idarubicin-based protocol (APML3), APML4 patients had statistically significantly improved freedom from relapse (P = .006) and failure-free survival (P = .01). In conclusion, the use of ATO in both induction and consolidation achieved excellent outcomes despite a substantial reduction in anthracycline exposure. This trial was registered at the Australian New Zealand Clinical Trials Registry (www.anzctr.org.au) as ACTRN12605000070639.

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.