Micallef, Ivana N.

Abstract Background: CpG 7909 is a synthetic 24 mer oligodeoxynucleotide designed to provide optimal activation of immune mechanisms through the TLR9 receptors on B-cells and plasmacytoid dendritic cells. In vitro CpG can upregulate CD20 expression as well as stimulate the immune system. Radioimmunotherapy (RIT) with anti-CD20 radioimmunoconjugates such as Zevalin produces responses in approximately 80% of patients with relapsed indolent lymphoma; however, only 30% obtain a complete response and 20% have long-term disease free survival. Objectives: To combine CpG 7909 with rituximab and Zevalin to enhance the response to RIT. Patients and Methods: Patients were eligible if they had biopsy proven relapsed, refractory, or residual CD20+ NHL. Disease types included relapsed indolent and aggressive B-cell NHL. Patients were required to have measurable disease, a platelet count >150,000, and an absolute neutrophil count >1,500. This was a phase I study where all patients received a standard dose of Zevalin (0.4mCi/kg with a maximum of 32mCi for patients over 80kg) along with a phase I dose of CpG 7909. Four dose levels were studied—0.08mg/kg; 0.16mg/kg; 0.32mg/kg; and 0.48mg/kg. CpG was dosed on Day 6, 13, 20, and 27; rituximab was provided Day 1, 8, and 15; indium-111 Zevalin on Day 1 and 8 (followed by indium-111 Zevalin imaging); and yttrium-90 Zevalin on Day 15. Response was assessed at week 4 and week 12. Patients are also being assayed pre- and post-CpG and at multiple time points up to 1 year following treatment for changes in T-cell, NK-cell, and cytokine levels. Results: A total of 30 patients have now been enrolled—6 at each of the first 3 dose levels and 12 at dose level 4. Three pts had relapsed diffuse large cell (DLC) and 27 pts were relapsed indolent. One of the first 6 patients at dose level 4 (0.48mg/kg) had a dose limiting toxicity (DLT - hematologic with full recovery). The other 5 patients at dose level 4 did not have DLT; and thus, 0.48mg/kg was determined to be the dose for further studies. An additional 6 patients at dose level 0.48mg/kg were accrued. Response information is available on the first 26 pts and the median follow-up is 12.4 months (range, 0–30.8). The overall response rate, to date, is 92% (24/26) – 66% (2/3) for the DLC pts and 96% (22/23) for the indolent pts. The complete remission rate is 58% (15/26). After follow-up, 7 of the 26 patients have progressed and one has died of relapsed NHL; therefore, 73% (19/26) remain in response and overall survival is 97% (29/30). As part of the study, we performed indium-111 Zevalin imaging before CpG and after 1 dose of CpG (prior to the yttrium-90 Zevalin) to evaluate the effect of CpG on the biodistribution of the radioimmunoconjugate. In the first 24 patients treated to date, review of the paired gamma camera images does not show any significant effects of CpG on tumor or normal organ biodistribution. To date, there has been no significant differences in T-cell, NK-cell, and cytokine activation by CpG dose level. Summary: CpG 7909 can be safely combined with Zevalin RIT in patients with advanced stage relapsed B-cell NHL.

Abstract Background: POEMS syndrome is a devastating syndrome, characterized by peripheral neuropathy, organomegaly, endocrinopathy, monoclonal plasma cells, skin changes, papilledema, volume overload, sclerotic bone lesions, thrombocytosis, & high VEGF. We noted an unexpectedly high transplant related morbidity, which we have since postulated to be ES. Methods: 30 patients with POEMS were treated with PBSCT at Mayo Clinic Rochester. We retrospectively studied outcomes, with an emphasis on treatment related morbidity. Two definitions of ES were used: Spitzer (BMT 2001) and Maiolino (BMT 2003). Results: Two-thirds were male. Median age was 48, range 20–70. Time from first symptoms and diagnosis was 26 and 4 months, respectively. To mobilize stem cells, CTX/G-CSF was used in 5 & G-CSF in the remainder. Conditioning was Mel200 (n=19), Mel140 (n=10), and BEAM (n=1). Post-transplant 15 had GM-CSF begun day+6. Only 10% remained outpatient, and median time to discharge from hospital was transplant day 17 (range 0–175). Factors predicting for later dismissal included age (p=0.04), abnormal CXR 7 to 17 days post transplant (p<0.0001), & bolus corticosteroids (CS) beyond day 12 post-transplant (p=0.006). Ninety-three percent had fever, although only 9 had bacteremia. Eight satisfied criteria for ES according to Spitzer and 14 according to Maiolino. Another 3 patients received steroid bolus days 8, 12, and 11 for presumed ES but did not meet criteria because of delayed ANC recovery (days 16, 18, and 20, respectively). Of the 5 patients requiring endotracheal intubation, 3 satisfied Maiolino’s criteria for ES. Although these 3 received bolus CS during their course, administration was delayed at 18, 14, and 18 days. The patient whose CS bolus antedated intubation only received prednisone 30 mg/day. In toto, fourteen patients received bolus CS (daily doses between 20 and 1200 mg prednisone equivalents) commencing day 8 to 59. Those 7 patients who received CS before day 13 did better than the 7 who received them day 13 or later (Table). Conclusions: It is essential to recognize that nearly 50% of patients satisfied formal criteria for ES as defined by Maiolino. In these patients ES may run a self-limited course or lead to catastrophe. No Steroid (n=16) Steroid ≤ D12 (n=7) Steroid > D12 (n=7) P *Engraftment syndrome according to definition of Maiolino (M) or of Spitzer (S). ES M / S, n* 5 / 2 4 / 4 5 / 2 NA Wt change, % 0.6 (−.4.2–6.7) 6.7 (3.6–27.2) 11.2 (–2.1–23.2) 0.005 Rash, % 27 71 43 0.13 Diarrhea, % 73 86 86 0.71 Tmax, C 39 (37.8–41) 40.1 (39–41.1) 38.9 (38.7–40.8) 0.08 1st fever, day 10 (6–15) 8 (7–9) 12 (8–146) 0.007 Abn CXR1, % 13 71 71 0.03 Ventilator, % 0 14 71 0.004 First WBC, day 12 (8–21) 14 (12–14) 14 (12–17) 0.03 ANC500, day 15 (12–29) 16 (14–115) 18 (15–45) 0.08 PLT20, day 12 (8–41) 20 (11–115) 24 (9–170) 0.05 PLT50, day 15 (11–192) 32 (16–115) 56 (13–551) 0.03 RBCs, units 3 (2–8) 6 (4–31) 11 (6–64) 0.0008 PLTS, aph. units 2 (1–9) 9 (4–51) 18 (4–60) 0.0004 Hosp dsm, day 15 (13–36) 21 (15–69) 41 (16–175) 0.009

Abstract Background: Clinical observations within our tertiary care setting suggested that atrial arrhythmia is common following hematopoietic stem-cell transplant (SCT). Yet little is known with regard to the incidence of such arrhythmia and factors contributing to its development. We assessed the frequency of first atrial fibrillation/flutter (AF/flutter) development in multiple myeloma (MM) patients who underwent SCT at the Mayo Clinic over a 4 year period. Method: Using a case-control design, we compared 395 consecutive patients who underwent SCT at the Mayo Clinic during the period 2002–2005 to control subjects who did not have SCT (2:1 matched by age, gender, and date of MM diagnosis) in terms of the baseline risk factors and the frequency of new AF/flutter after MM diagnosis. Patients who had a prior history or evidence of atrial arrhythmia were excluded from analyses. Factors predictive of atrial arrhythmia in the cases were also determined. Results: First AF/Flutter developed in 38 of 395 cases (mean age 58 ± 9 years) and 47 of 790 controls subjects within 5 years of MM diagnosis (P=0.002). The 5-year Kaplan-Meier estimates of the risk of AF/flutter were 17% and 8% for cases and controls, respectively. Amongst the cases who developed new AF/flutter, the onset of the arrhythmia was within 21 days of SCT for the majority (94%). In multivariable analysis, body weight change of ≥3% in the first week post-transplant (HR 2.86; CI 1.13–7.24; P=0.026) and presence of diastolic dysfunction (HR 1.79; CI 0.99–3.23; p=0.054) at MM diagnosis were independent predictors of first AF/flutter in the cases, adjusting for age, sex, and well established clinical risk factors. Conclusion: The risk for new AF/flutter was remarkably high in the early post- SCT period in MM patients. In addition to established risk factors for atrial arrhythmia, a weight change ≥3% during the first 7 days after SCT, and the presence of diastolic dysfunction at baseline, were independent novel risk factors for new AF/flutter. These findings warrant further investigation, as modification of fluid management and diastolic filling may potentially lower the risk of post-SCT atrial arrhythmia.

Abstract Peripheral blood absolute lymphocyte count (ALC) at diagnosis is a predictor of survival in B-cell lymphomas. The role of ALC at diagnosis on survival in T-cell lymphoma has not been studied. Thus, we studied the role of ALC at diagnosis on clinical outcome in adult patients with primary anaplastic large cell lymphoma (PALCL) that were diagnosed, treated, and followed at the Mayo Clinic, Rochester. Between 1985 and 2006, 50 patients with PALCL qualified for the study. ALC was identified to be a strong predictor for complete response (CR), area under the curve (AUC = 0.83, p < 0.002). The median follow-up was 31.8 months (range: 1–212.6 months). ALC, as a continuous variable was a predictor for overall survival (OS) (HR = 0.143; 95%CI = 0.042–0.416; p < 0.0001) and progression-free survival (PFS) (HR = 0.150; 95%CI = 0.047–0.415; p < 0.0001) .Superior OS and PFS (Figure 1) were observed with an ALC ≥ 1.0 x 109/L (N = 31) versus an ALC < 1.0 x 109/L (N=19) (median OS: not reached vs 7.5 months, OS rates at 5 years, 81% vs 36%, p < 0.0006, respectively; and median PFS: not reached vs 6.3 months; PFS rates at 5 years, 77% vs 37%, p < 0.0007, respectively). Multivariate analysis demonstrated ALC to be an independent prognostic indicator for OS (HR = 0.196; 95%CI = 0.125–0.693; p < 0.002) and PFS (HR = 0.191; 95%CI = 0.053–0.559; p < 0.0008) when compared to anaplastic lymphoma kinase, international prognostic index, and cutaneous versus systemic presentation. Figure 1 Figure 1.

Abstract Abstract 2682 Background: The PI3K-Akt pathway is critical to tumor growth in lymphoid malignancies and mTOR inhibitors have shown promising activity in lymphoid malignancies. However, alternate signaling pathways allow cells to escape the effect of mTOR inhibition. Pre-clinical studies have shown that the combination of LBH589, an HDAC inhibitor, with the mTOR inhibitor RAD001 results in potent synergy. We then explored this combination in a phase I/II clinical trial. Patients and Methods: Patients with relapsed multiple myeloma (MM), non-Hodgkin lymphoma (NHL) or Hodgkin Lymphoma (HL) were enrolled into a phase I trial of escalating doses of LBH589 and RAD001. The doses are shown in the table. The study utilized a 3+ 3 design with MTD defined as the maximum dose resulting in less than 2 dose limiting toxicities (DLT) during the first cycle among 6 patients treated at that dose. DLT was defined as a grade 4 neutropenia or thrombocytopenia lasting >= 7 days, febrile neutropenia or any other grade >=3 non-hematologic toxicity considered possibly related to the drugs. Once MTD was determined, patients were enrolled into two separate phase 2 studies, one for relapsed MM and another for relapsed NHL or HL. Results: Twenty-six patients were enrolled to the phase 1 study; 23 were eligible for MTD analysis. There were 16 patients with NHL, 4 with HL and 3 with MM. Median age was 61 (range, 24–73) and 17 were male. The median number of prior therapies was 4 (range 2–11), including a prior stem cell transplant in 11 (48%). No DLT was observed at any of the doses tested in the trial (See below). Hematological toxicities were the most common AEs observed, with a grade 3 or 4 hematologic AE in 15 patients and grade 3 or 4 non-hematologic AEs in 6 patients across all cycles administered. Grade 3 and 4 hematologic AEs included 10 patients with neutropenia and 8 patients with thrombocytopenia. Grade 3 and 4 non-hematologic AEs included hyperglycemia, hypertriglyceridemia, hypophosphatemia, diarrhea, pneumonia and mucositis in one patient each. Overall, 10 responses (43%) were seen (Table). Conclusions: The combination of LBH589 and RAD0001 is tolerated at the doses tested, with hematological toxicities being the most common adverse events. The recommended phase II dose is LBH 40 mg MWF every other week along with 5 mg RAD001 every day in 4-week cycles. Clinical efficacy was seen in all diseases tested with partial responses seen in NHL and HL as well as a minor response in a patient with refractory myeloma, who had previously failed single agent RAD001. Phase 2 trials are ongoing in both disease groups. Disclosures: Kumar: Merck: Consultancy, Honoraria; Celgene: Consultancy, Research Funding; Millennium Pharmaceuticals, Inc.: Research Funding; Genzyme: Research Funding; Novartis: Research Funding. Off Label Use: Use of the investigational agent MLN9708 for the treatment of previously untreated multiple myeloma. Lacy:Celgene: Research Funding. Reeder:Celgene: Research Funding; Millennium Pharmaceuticals Inc.: Research Funding; Novartis: Research Funding.

Abstract Abstract 3642 Purpose: The reactive pathologic background in nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) consists of lymphocytes and histocytes. Lymphopenia is a negative prognostic factor in NLPHL as it is also in Classical Hodgkin Lymphoma (cHL). In cHL, tumor-associated macrophages recruited from circulating monocytes are a negative prognostic factor for survival. Thus, we studied if the peripheral blood absolute lymphocyte count/absolute monocyte count ratio at diagnosis (ALC/AMC-DX), as a surrogate biomarker of the host response against the neoplastic lymphocytic and/or histiocytic (L&H) cells, affects survival in NLPHL. Patients and Methods: We performed a retrospective analysis of the association between ALC/AMC-DX and survival in 103 consecutive NLPHL patients that were followed at Mayo Clinic from 1974 to 2010. Receiver operating characteristic (ROC) and area under the curve (AUC) were used for ALC/AMC-DX cut-off value analysis and proportional-hazards models were used to compare survival based on the ALC/AMC-DX ratio. Results: The cohort included 67 (65%) males and 36 (35%) females. Eighty-three percent of patients presented with stage I/II and 17% with stage III/IV. Sixty-five (63%) patients were treated with radiation alone; 20 (20%) patients with chemotherapy alone; and 18 (17%) patients with chemotherapy and radiation. The median follow-up period was 8.9 years (range: 0.3–31 years). An ALC/AMC-DX ≥ 2.1 was the best cut-off value for survival with an empirical AUC of 0.82 (95% confidence interval [CI], 0.78 to 0.88), a sensitivity of 70% (95% CI, 61% to 76%) and specificity of 84% (95%CI, 59% to 82%). The cut-off value for ALC/AMC-DX ≥ 2.1 was validated by the k-fold cross validation method, showing a cross validation ROC with an AUC of 0.82 (95% CI, 0.72 to 0.93) for an ALC/AMC-DX ≥ 2.1. Using Kaplan-Meier analysis, we studied overall survival (OS), lymphoma-specific survival (LSS), progression-free survival (PFS), and time to progression (TTP) based on ALC/AMC-DX ≥ 2.1. Patients with an ALC/AMC-DX ≥ 2.1 experienced an superior OS, LSS, PFS, and TTP compared with patients with an ALC/AMC-DX < 2.1: [OS: median was 22.1 years vs 6.3 years, 10-years OS rates of 89% (95%CI, 80% to 98%) vs 44% (95%CI, 27% to 65%), p < 0.0001, respectively; LSS: median was not reached vs 7.3 years, 10-years LSS rates of 99% (95%CI, 90% to 100%) vs 45% (95%CI, 29% to 67%), p < 0.0001, respectively; PFS: median was 20.6 years vs 4.6 years, 10-years PFS rates of 84% (95%CI, 80% to 97%) vs 26% (95%CI, 18% to 55%), p < 0.0001, respectively; and TTP: median was not reached vs 5.5 years, 10-years TTP rates of 93% (95%CI, 85% to 99%) vs 29% (95%CI, 19% to 57%), p < 0.0001, respectively]. After adjusting for the International Prognostic Factors and the International Prognostic Score, ALC/AMC-DX remained an independent prognostic factor for OS {hazard ratio (HR), 0.42, 95%CI, 0.23 to 0.64, p< 0.004]; LSS [HR, 0.14; 95%CI, 0.04 to 0.23, p <0.0004]; PFS [HR, 0.14; 95%CI, 0.03 to 0.34, p < 0.001], and TTP [HR, 0.16, 95%CI, 0.04–0.34, p <0.002]. Conclusion: ALC/AMC-DX is an independent prognostic factor for survival and provides a single biomarker to predict clinical outcomes in NLPHL. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 996 Background: Treatment with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) has improved survival in diffuse large B-cell lymphoma (DLBCL) lymphoma, although a significant percentage of patients do not achieve a remission or they relapse. One potential explanation for this observation is that host pharmacogenetic background may impact metabolism, detoxification and transport of R-CHOP. However, there are few prospectively collected data that address pharmacogenetics in DLBCL, particularly for event-free and overall survival in the rituximab era. We therefore tested the hypothesis that functional candidate single nucleotide polymorphisms (SNPs) from genes involved in the metabolism of CHOP (CYP2C19, CYP3A5, ABCB1, ABCC2, ABCG2, RAC2, CYBA, NR3C1, GSTA1, GSTP1, TP53) and rituximab (FCGR2A, FCGR3A) influence prognosis in DLBCL. Methods: We genotyped 19 SNPs from 13 genes in a prospective cohort of newly diagnosed DLBCL patients with germline DNA enrolled at the Mayo Clinic and University of Iowa from 2002–2008 as part of the Molecular Epidemiology Resource of the Iowa/Mayo Lymphoma SPORE. All patients were systematically followed through 2009 for overall survival (OS) and event-free survival (EFS), defined as disease progression, retreatment or death due to any cause. All SNPs were genotyped on the Illumina Golden-Gate platform. Cox regression was used to estimate Hazard Ratios (HRs) and 95% confidence intervals (CI) for individual SNPs with OS and EFS. Each SNP was modeled with the most prevalent homozygous genotype used as the reference group. An ordinal test was used to assess the trend across genotypes, and a p<0.05 was considered statistically significant. All Cox models adjusted for International Prognostic Index (IPI) and treatment. Results: The median age at diagnosis of the 439 DLBCL patients was 62 years (range 18–92). The IPI was distributed as follows: 0–1 (34%), 2 (26%), 3 (24%) and 4–5 (16%). All patients were treated with chemotherapy, and 91% received R-CHOP. Through 2009, there were 171 events (39%) and 122 (28%) deaths, with a median follow-up for living patients of 49 months (range 1–98). The SNP rs1045642 in the ATP-binding cassette (ABC) protein gene ABCB1 was associated with OS (p=0.012). The variant T allele for ABCB1 rs1045642 (minor allele frequency (MAF)=0.47) is associated with a silent I→I substitution, and the T allele predicts low enzyme expression. Compared to CC homozygotes, patients with CT (HR=0.66, 95% CI 0.44–0.99) or TT (HR=0.53, 95% CI 0.31–0.90) genotypes had superior OS. We also observed an association of the GSTP1 SNP rs1695 with OS (p-trend=0.018). The variant G allele (MAF of 0.31) is associated with an A→V substitution, and this change predicts low enzyme expression. Compared to AA homozygotes, patients with the AG (HR=0.78, 95% CI 0.54–1.14) or GG (HR=0.39, 95% CI 0.17–0.90) genotypes had superior OS. Nearly identical associations for these two SNPS were observed with EFS. There were no significant associations with any of the other SNPs that we evaluated. Conclusions: In a large series of newly diagnosed DLBCL patients treated in the rituximab era, we found evidence that genetic variation in ABCB1 and GSTP1 is associated with improved OS and EFS after adjusting for IPI and treatment. The variant allele for ABCB1 is associated with slower enzyme activity, favorably impacting doxorubicin and vincristine pharmacodynamics, and the variant allele for GSTP1 is associated with slower detoxification of doxorubicin and vincristine, increasing bioavailability of these drugs. A comprehensive evaluation of the role of pharmacogenetics in DLBCL is warranted. Support: P50 CA97274, R01 CA129539. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 1648 Introduction Radioimmunotherapy capitalizes on the radiosensitivity of non-Hodgkin lymphoma (NHL) and the targeted nature of monoclonal antibody therapy. In an attempt to reverse bone marrow infiltration with B-cells and, hence, optimize the biodistribution and tumor dosimetry of 90Y-ibritumomab tiuxetan, we conducted a multicenter, dose escalation, open label study to determine maximum tolerated dose (MTD), safety, and efficacy of a single course of 90Y-ibritumomab tiuxetan after four weekly doses of rituximab in relapsed or refractory low-grade or follicular or transformed CD20+ B-cell NHL. Methods A course of therapy included an initial dose of rituximab 250 mg/m2 plus 5 mCi of 111In- ibritumomab tiuxetan followed by three weekly doses of rituximab at 375 mg/m2 followed two weeks later by rituximab 250 mg/m2 plus 5 mCi of 111In-ibritumomab tiuxetan. Gamma camera imaging for dose estimates was conducted on days 1 and 36 following infusion of 111In- ibritumomab tiuxetan. If dose estimates were in the safe defined limits, and bone marrow on day 29 had less than 25% involvement by NHL, patients received on day 43 250 mg/m2 of rituximab plus a dose of 90Y-ibritumomab tiuxetan. Patients were scheduled to receive 90Y- ibritumomab tiuxetan in one of the dose escalation cohorts (0.4, 0.5, 0.6, 0.7 mCi/kg). Eligible patients were required to have histologically confirmed, relapsed or refractory low-grade or follicular or transformed B-cell NHL with demonstrable monoclonal CD20+ B-cell population in the lymph nodes or bone marrow. Patients with impaired bone marrow reserve, as indicated by prior myeloablative therapies with stem cell rescue, hypocellular marrow, history of failed stem cell collection or external beam radiation therapy to >25% of active bone marrow, and marked reduction in bone marrow precursors of one or more cell lines, were excluded. Results Cohort 1 (0.4 mCi/kg) enrolled 5 patients. Dose escalation was held after significant hematologic toxicity was observed in those patients (1 patient developed grade 4 and 3 grade 3 reversible thrombocytopenia, 4 patients developed grade 4 reversible leukopenia and neutropenia, and 1 patient developed grade 4 febrile neutropenia). One patient in this cohort did not receive the study drug due to the toxicity observed in the previous patients. The protocol was amended and 6 patients were enrolled at a lower dose cohort (0.3 mCi/kg); 1 patient experienced grade 4 neutropenia, whereas grade 3 leukopenia, neutropenia, and thrombocytopenia were seen in 2, 3, and 3 patients respectively. As the 0.3 mCi/kg dose was well tolerated, the 0.4 mCi/kg cohort was expanded to enroll 6 additional patients. In the expansion cohort, Grade 4 leukopenia and neutropenia were seen in 1 and 2 patients respectively; also, grade 3 leukopenia, neutropenia, and thrombocytopenia were seen in 3, 4, and 4 patients, respectively. All hematologic toxicities were reversible and no non-hematologic toxicities were seen with the exception of grade 1 fatigue in 2 patients. Among those who developed hematologic toxicities, the median duration of at least grade 3 leukopenia, neutropenia, and thrombocytopenia were 12 (range, 7–37), 10 (7–30), and 12 (3–44) days, respectively. Six patients had bone marrow involvement by NHL at registration ranging from <5% to 20%. Following 4 weekly doses of rituximab, marrow involvement decreased in all patients with complete clearance in 3 of them. In an intention-to-treat analysis, complete remission, partial remission, stable and progressive disease was achieved in 6 (35%), 8 (47%), 2 (12%), and 1(6%) patients, respectively (fig 1). With a median follow up of 31.7 months (range, 4.3 – 92.6 months), the median progression free survival (fig 2) and time to next treatment (fig 3) were 12.3 and 10.9 months, respectively. The median overall survival has not been reached. Conclusion The MTD of 90Y-ibritumomab tiuxetan administered to patients who have NHL marrow infiltration <25% following 4 weekly doses of rituximab was 0.4 mCi/kg. A 4 weekly course of rituximab decreased NHL marrow infiltration in all patients with marrow involvement and led to complete clearance in 50% of them. Although this regimen was associated with a high response rate, the hematologic toxicity was significant. Disclosures: No relevant conflicts of interest to declare.

Abstract We have recently reported that event-free survival at 24 months from diagnosis (EFS24) is a robust endpoint for assessment of disease related outcome for newly diagnosed patients with diffuse large B-cell lymphoma (DLBCL) treated with anthracycline-based immunochemotherapy (IC). Patients who achieve EFS24 following IC have a subsequent overall survival that is equivalent to the age and sex matched general population. The IPI was developed in the pre-rituximab era using OS/EFS endpoints. While the IPI is associated with outcome in the IC era, the original survival estimates for the IPI risk groups are outdated. The IPI is also a discrete risk classifier, with only 6 possible groups. Here we remodel the IPI using EFS24 as the endpoint in a large international cohort of patients treated with IC. This model provides an individual level 0-100% risk of failing to achieve EFS24 for each patient and can be used for patient prognosis, treatment stratification, and risk assessment. Methods Newly diagnosed DLBCL patients treated with immunochemotherapy from the University of Iowa/Mayo Clinic SPORE Molecular Epidemiology Resource, NCCTG N0489 clinical trial, GELA LNH2003B program, and a Lyon, France based hospital registry were included in the original EFS24 study. Patients with a relapse, progression, unplanned re-treatment, or death due to any cause within 730 days of diagnosis were considered a failure for the EFS24 endpoint. Patients alive and progression/relapse free at 730 days from diagnosis with no subsequent treatment following initial IC were considered a success for the EFS24 endpoint. Variables selected for potential model inclusion were the IPI components (age, stage, ECOG PS, number of extranodal sites, and LDH), as well as standard clinical variables typically reported in studies of DLBCL: presence of B-symptoms, bone marrow involvement, bulky disease (>10 cm), and sex. The IPI24, a prognostic model for EFS24, was developed using logistic regression models. Model building began by fitting the classic IPI score (0-5), then allowing individual IPI variables to carry different model weights and number of categories, followed by dropping insignificant variables, finally adding any additional significant variables. Model performance was assessed using bias corrected c-statistics, AIC, and R2 values. Model selection was done using the complete case set with multiple imputation on the full dataset used to refine parameter estimates for the final model. Results 1596 total patients were available for modeling. The median age was 62 (range 18-93) and 53% were male; 33% were IPI 0-1, 25% were IPI 2, 25% were IPI 3, and 17% were IPI of 4-5. The failure rate for achieving EFS24 was 29%. All variables but sex (p=0.33) were univariately associated with EFS24 (p<6.4x10-5). The original IPI had good prognostic ability for EFS24 (c=0.696, p=2.2x10-32). Allowing multiple categories for ECOG PS, stage, and age (continuous) improved model fit and prognostic ability (c=0.727). The number of extranodal sites was not significant when IPI variables were modeled separately and was removed from the model. Sex and bulky disease were additional significant variables when added to the model. Thus, the final IPI24 model contained the following risk predictors: male sex, ECOG PS (0 vs. 1 vs 2 vs 3-4), stage (I vs. II, vs. III vs. IV), LDH (elevated vs. normal range), bulky disease > 10cm, and age (continuous). This model resulted in improved fit and prognostic ability (c=0.749) over the standard IPI (c=0.696, bootstrap p<0.001). Model validation was performed on an additional 158 patients from the SPORE MER and showed good concordance (c=0.697). Additional validation is planned in a larger set of independent patients. Conclusion The IPI24, generated using standard clinical variables, yields an individual risk prediction for failing to achieve EFS24 following IC for treatment of DLBCL. The IPI24 has superior prognostic ability to the standard IPI and can be implemented in the clinic using a nomogram or as a simple electronic application. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 1640 Background: The introduction of radioimmunotherapy (RIT) into clinical practice for the treatment of follicular lymphoma (FL) occurred at a time at which many patients did not have prior exposure to rituximab. Clinical trials in the relapsed/refractory setting, as well as consolidation in the upfront setting have included a small number of patients that had been previously treated with rituximab or a rituximab containing treatment regimen. We evaluated the effect of prior rituximab therapy on the efficacy of RIT. METHODS: The prospective lymphoma database was queried for all patients having received a single dose of yttrium-90 ibritumomab tiuxetan for relapsed/refractory FL which had previously been treated with systemic therapy (patients receiving only prior external beam radiation therapy were excluded). The database includes all consecutive adult patients diagnosed with lymphoma seen at Mayo Clinic Rochester. The diagnosis of follicular lymphoma was as by WHO classification and centrally reviewed. Patients with evidence of histologic transformation to diffuse large B cell lymphoma prior to RIT were excluded. Time to treatment failure (TTF) was defined as the time from RIT to next anti-lymphoma therapy. RESULTS: 111 patients were identified. 57 (51%) were male. Median age at time of RIT was 58 (19–88). Median time from diagnosis to RIT was 35 (6–281) months in patients having received prior treatment with rituximab and 47 (12–272) months in those who had not (p=0.19). 63 (57%) of patients received prior treatment with rituximab or rituximab containing chemotherapy. Median number of prior therapies was 2 (1–10), which was not different between the rituximab treated or untreated groups [2(1–6) vs 2(1–10) p=0.12]. Median TTF was 10.0 months in the patients having received prior rituximab and 10.1 months in those that had not (p=0.29). Figure 1. The median overall survival from RIT was not reached, but appeared similar (Kaplan-Meier estimate 125 months without prior rituximab exposure vs 95 months with prior rituximab exposure; p=0.33). CONCLUSIONS: Prior rituximab exposure does not seem to adversely impact the time to treatment failure or overall survival in those patients treated with RIT. While the data leading to the approval of RIT were accrued prior to the routine clinical use of rituximab, our data demonstrate similar clinical benefit of RIT in patients with prior exposure to rituximab or rituximab containing therapy. Disclosures: No relevant conflicts of interest to declare.