Citations

Abstract Abstract 448 Background: POEMS syndrome is a rare form of plasma cell dyscrasia that presents with polyneuropathy and various other systemic findings. Patients with 1–3 lesions and bone marrows without clonal plasma cells have been given targeted radiation as the initial and potentially definitive therapy. Outcomes of patients treated thus have not been systematically studied. Patients and Methods: One hundred and forty-six patients with POEMS syndrome were seen at the Mayo Clinic in Rochester, MN between January 1999 and September 2011. Charts of patients with research authorization were reviewed with IRB approval. Patients who had been given targeted radiation as their initial primary therapy were eligible for this study. Thirty-eight patients satisfied criteria and comprise the study population. Three patients had either short or poorly documented follow-up and were excluded from the response and time to next treatment analyses. Patients were categorized by systems that were involved at diagnosis, time of radiation, response after radiation, and the need for further therapy. Statistical analyses were performed using JMP statistical software (SAS, Carey, NC). Results: The median age was 50, with 76% of the population being male. Median time from diagnosis to radiation was 0.7 months, ranging from 0 to 9.4 months. 20, 14, 11 and 2 patients had immunosuppressive therapy with corticosteroids, IVIG, plasmapheresis, or rituximab, respectively, directed at a prior presumptive, but incorrect, diagnosis of CIDP. Five patients had one cycle or less of alkylator, lenalidomide, or bortezomib, prior to receiving what was hoped to be definitive radiation therapy. The median number of bone lesions was 1, range 1–6. In total 55 lesions of the possible 64 were irradiated being mostly found in the pelvic bones including the sacrum, ileum, ischium, and pubis. The median dose of radiation given was 45 Gy range 35 Gy to 54 Gy. Forty-nine percent had clinical improvement, 26% had a mixed clinical picture, 3% merely stabilized, and 23% had a clinical worsening. 29% had a complete hematologic response, 9% had a very good partial hematologic response, 9% had a partial hematologic response, 26% had no hematologic response, and the remaining were either non- or oligo-secretory or undocumented. 11% had a complete FDG-PET response, 11% had a partial FDG-PET response, 11% had no FDG-PET response, and the remaining had no documented FDG-PETs to analyze. 11% had a complete VEGF response, 3% had partial VEGF response, 14% had no VEGF response, and the rest were either not documented or unevaluable. The median follow up of living patients is 30 months, and the 4-year OS is 95%. Forty-eight percent of patients went on to receive additional therapy after their radiation (Figure). The median time to next therapy (TTNT) for these patients was 7.6 months (range 2.2 –73 months). Subsequent therapies included high dose chemotherapy with autologous hematopoietic stem cell transplant (n=10), low dose alkylator (n=2), thalidomide/lenalidomide (n=3), and more radiation (n=3). None of the baseline characteristics predicted for whether a patient would receive (or require) subsequent therapy, including the number of bone lesions at baseline. Conclusion: The results show that radiation is sufficient to produce clinical improvements and hematologic and radiographic responses approximately 50% of patients, even those with as many as 3 lesions. Disclosures: No relevant conflicts of interest to declare.

Abstract Introduction Del(17p) detected by fluorescence in situ hybridisation (FISH) of bone marrow plasma cells (BMPCs) is an adverse prognostic factor in patients with multiple myeloma (MM). While the natural history and prognostic factors in patients with del (17p) detected at diagnosis have been studied, the outcomes of patients who acquire del (17p) later in their course are not known. We aimed to define the outcomes of MM patients who acquire del(17p). Methods We reviewed the Dysproteinemia database at Mayo Clinic, MN to identify 80 patients with MM who had their first FISH test negative for del (17p), but acquired del(17p) later in the course of the disease. Sixty (75%) patients had their first FISH within 6 months (mo) of diagnosis; 20 (25%) patients had their first FISH more than 6 mo after diagnosis of MM. Del(17p) included del(17p13.1) and/or monosomy 17. We identified 2 control patients for each case, who were diagnosed during the same time period, but did not demonstrate del (17p) at any time during follow-up. Results Characteristics of patients at acquisition of del(17p) are shown in Table 1. Of these, 76 patients had relapsed and/or refractory MM; in 4 patients, del (17p) was detected after having attained a response to prior therapy. Seventy (87.5%) patients had del (17p13.1); 5 (6.3%) patients had monosomy 17; 1 (1.2%) patient had both del (17p13.1) and monosomy 17. Four (5.0%) patients had relative loss of 17p. High-risk translocations (HRT) [t(4;14), t(14;16) and t(14;20)] were present in 14 (17.5%) patients. The percentage of PCs with del(17p) were available in 75 patients. The median percentage of PCs with del(17p) was 76 (range, 9-100). Sixty two (77.5%) patients received exclusively chemotherapy as subsequent treatment; stem cell transplant (SCT) was part of the next treatment in 16 (20%) patients (allogeneic SCT in 1). Among 71 evaluable patients, ≥very good partial response and ≥partial response were attained in 24 (33.8%) and 35 (49.2%) patients respectively. The median progression free survival (PFS) from detection of del (17p) was 5.7 mo (95% CI, 3.5-7.8); overall survival (OS) was 18.2 mo (CI, 13.1-27.5). From a comparable time point, the OS for 160 controls was 56.2 mo (CI, 37.1-75.3) (P<0.001). The results were similar when patients were stratified based on variables at diagnosis such as age, presence of HRT, international staging system (ISS) stage, serum lactate dehydrogenase (LDH) and PC proliferative rate, and proteasome inhibitor (PI)-containing induction and SCT within a year of diagnosis and before acquisition of del(17p). Evaluating outcomes from initial diagnosis, PFS in the acquired del (17p) and control groups were 23.0 (CI, 20.2-25.8) and 30.2 (CI, 26.7-33.9) mo (P=0.028) and OS were 68.2 (CI, 50.8-74.8) and 111.6 (CI, 103.4-127.8) mo respectively (P<0.001). High LDH at baseline [OR- 4.31 (CI, 1.34-13.86)] predicted acquisition of del(17p) while presence of HRT showed borderline significance [OR- 2.02 (0.90-4.54)]. Age ≥65 yrs, ISS III vs. I/II stage, t(11;14), any trisomy, monosomy 13, BMPC%, initial therapy and SCT in first year and before acquiring del (17p) were not predictive. We performed univariable analysis with variables at detection of del(17p) such as age ≥65 vs. <65 years, serum creatinine >2 vs. ≤2 mg/dL, BMPC% ≥50 vs. <50%, ISS III vs. I/II stage, elevated vs. normal LDH, presence vs. absence of a HRT, presence vs. absence of monosomy 13, presence vs. absence of any trisomy, high vs. low PC proliferation rate, PI and immunomodulatory drug (IMiD)-refractoriness and percentage of PCs with del(17p) as independent variables to determine their association with PFS and OS. ISS stage III, high PC proliferative rate and PI and IMiD-refractoriness were selected after univariable analysis and included in the multivariable Cox proportional hazards model. A higher PC proliferative rate alone predicted shorter OS. None of the above factors were associated with shorter PFS. The median OS in those with high PC-proliferative rate from detection of del(17p) was 10.9 mo (CI, 6.0-17.1) vs. 37.2 mo (CI, 18.2-47.5) in those with low PC proliferative rate (P=0.005). Conclusion The prognosis of patients who acquire del (17p) is poor with OS of 6.5 years against 9 years from diagnosis in patients who do not acquire del (17p). This was valid across prognostic sub-groups. High PC proliferative rate was the only factor which impacted OS once patients acquired del(17p). Disclosures Kapoor: Celgene: Research Funding; Takeda: Research Funding. Gertz:Research to Practice: Consultancy; Teva: Consultancy; Ionis: Honoraria; annexon: Consultancy; Physicians Education Resource: Consultancy; Abbvie: Consultancy; spectrum: Consultancy, Honoraria; Prothena: Honoraria; Alnylam: Honoraria; Apellis: Consultancy; Medscape: Consultancy; Amgen: Consultancy; janssen: Consultancy; celgene: Consultancy. Lacy:Celgene: Research Funding. Dingli:Alexion Pharmaceuticals, Inc.: Other: Participates in the International PNH Registry (for Mayo Clinic, Rochester) for Alexion Pharmaceuticals, Inc.; Alexion Pharmaceuticals, Inc.: Other: Participates in the International PNH Registry (for Mayo Clinic, Rochester) for Alexion Pharmaceuticals, Inc.; Millennium Takeda: Research Funding; Millennium Takeda: Research Funding. Dispenzieri:Celgene, Takeda, Prothena, Jannsen, Pfizer, Alnylam, GSK: Research Funding. Russell:Vyriad: Equity Ownership. Kumar:AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Abstract RNA-binding proteins (RBPs) regulate many aspects of transcription and translation in a cell- and tissue-specific manner and are frequently dysregulated in malignancy. We systematically evaluated RBPs preferentially required in acute myeloid leukemia (AML) over other forms of cancer or normal hematopoietic precursors using a CRISPR/Cas9 domain-based, loss-of-function screen targeting 490 classical RBPs with 2,900 sgRNAs (Fig. A). This screen was performed in cells lines representing AML, T-cell acute lymphoblastic leukemia (T-ALL), and lung adenocarcinoma (LUAD) and revealed multiple RBPs preferentially required for AML survival, but not for T-ALL or LUAD survival. We identified genes encoding 21 RBPs that were >3-fold depleted in AML cells and significantly overexpressed in AML patient samples versus normal adult CD34+ precursors (p-value < 0.05; Fig. B). Amongst RBPs required and upregulated in AML was RBM39, an RBP described to be involved in a number of cellular processes and to interact with key splicing proteins SF3B1 and U2AF2. Genetic ablation of Rbm39 in mouse MLL-AF9 leukemia cells dramatically delayed AML development and progression (Fig. C). In parallel, it has recently been described that a class of clinically-validated anti-cancer sulfonamide compounds (including indisulam and E7820) mediate RBM39 degradation as their dominant cellular mechanism of action. This occurs via novel interactions with the DCAF15 adapter protein of the CUL4/Ddb1 ubiquitin ligase complex with RBM39 as a neo-substrate. Treatment of MOLM-13 cells xenografted into mice with indisulam conferred significant anti-leukemic effects and improved overall survival (Fig. D). To explore the mechanism of RBM39 dependence in AML, we performed proteomic analyses of RBM39 interacting proteins in MOLM-13 cells as well as transcriptome-wide analysis of RBM39 RNA binding by enhanced UV cross-linking and immunoprecipitation (eCLIP) in the same cells. RBM39 physically interacted with an entire network of RBPs identified by our CRISPR screen as crucial for AML cell survival in addition to interacting with the core SF3b splicing complex. Further, anti-RBM39 eCLIP revealed RBM39 binding to exonic regions and most enriched at exon/intron borders at 5' and 3' splice sites of pre-mRNA (Fig. E), suggesting a prominent role of RBM39 in regulating splicing. Consistent with this, RNA-sequencing of AML cells following RBM39 deletion revealed significant effects of RBM39 loss on RNA splicing, most prominently causing increased cassette exon skipping (Fig. F). Recent studies suggest that myeloid leukemias with mutations in RNA splicing factors are sensitized to pharmacologic perturbation of RNA splicing. Analysis of the effects of RBM39 degrading compounds over a panel of 18 AML cells revealed that leukemia cells bearing splicing factor mutations or with high DCAF15 expression were the most sensitive to treatment (Fig. G). Genetic introduction of SF3B1, SRSF2, or U2AF1 hotspot mutations in K562 or NALM6 cells resulted in a 20-50% reduction in IC50 in response to sulfonamides. We next performed RNA sequencing of isogenic K562 cells with or without knockin of SF3B1K700E and SRSF2P95H mutations into the endogenous loci, and treated at the IC50 of E7820 or E7107, a small molecule that inhibits the SF3b core spliceosome complex. Treatment with either drug dramatically increased cassette exon skipping events and intron retention relative to DMSO control, with greater effects in splicing mutant cells. However, at equipotent doses, E7820 markedly increased mis-splicing compared with E7107. Furthermore, E7820 treatment resulted in mis-splicing of a number of RBP targets identified in our CRISPR screen as being required for AML survival, including SUPT6H, hnRNPH, and SRSF10, as well as RBM3 and U2AF2, consistent with previous observations (Fig. H). Here through systematic evaluation of RBPs across several cancers, we identify RBPs specifically required in AML. In so doing we identify a network of functionally and physically interacting RBPs upregulated in AML over normal precursors. Genetic or pharmacologic elimination one such RBP, RBM39, led to aberrant splicing of multiple members of this RBP network as well as of transcriptional regulators required for AML survival. These data suggest important clinical potential for anti-cancer sulfonamide treatment in splicing mutant myeloid leukemias. Disclosures Uehara: Eisai: Employment. Owa:Eisai: Employment.

AbstractNF-κB and Notch signaling can be simultaneously activated in a variety of B-cell lymphomas. Patients with B-cell lymphoma occasionally develop clonally related myeloid tumors with poor prognosis. Whether concurrent activation of both pathways is sufficient to induce B-cell transformation and whether the signaling initiates B-myeloid conversion in a pathological context are largely unknown. Here, we provide genetic evidence that concurrent activation of NF-κB and Notch signaling in committed B cells is sufficient to induce B-cell lymphomatous transformation and primes common progenitor cells to convert to myeloid lineage through dedifferentiation, not transdifferentiation. Intriguingly, the converted myeloid cells can further transform, albeit at low frequency, into myeloid leukemia. Mechanistically, coactivation of NF-κB and Notch signaling endows committed B cells with the ability to self renew. Downregulation of BACH2, a lymphoma and myeloid gene suppressor, but not upregulation of CEBPα and/or downregulation of B-cell transcription factors, is an early event in both B-cell transformation and myeloid conversion. Interestingly, a DNA hypomethylating drug not only effectively eliminated the converted myeloid leukemia cells, but also restored the expression of green fluorescent protein, which had been lost in converted myeloid leukemia cells. Collectively, our results suggest that targeting NF-κB and Notch signaling will not only improve lymphoma treatment, but also prevent the lymphoma-to-myeloid tumor conversion. Importantly, DNA hypomethylating drugs might efficiently treat these converted myeloid neoplasms.

Abstract Background: Limited data exist regarding histological transformation in patients with Waldenström macroglobulinemia (WM). In this study, we present the disease characteristics, outcomes and risk factors for histological transformation in WM. Methods: Patients with WM seen at Mayo Clinic, Rochester, MN between January 1996 and December 2017 were included. Patients with aggressive non-Hodgkin lymphoma in the setting of WM were considered to have transformation. Univariate analysis for comparing baseline characteristics of transformed versus non-transformed WM was performed using Wilcoxon, Fisher's exact and Chi square tests, as appropriate. Multivariate analysis was performed using logistic regression analysis. Cox proportional hazard method was used to assess the impact on time-to-transformation. All time-to-event analyses were calculated by the Kaplan-Meier method. Results: Of 1014 patients with WM, 42 patients (4.1%) developed histological transformation. The median follow-up for the entire cohort was 9.5 years (95% CI: 8.8-10.5 years). The cumulative probability of transformation was 2.3% at 5 years, 5.3% at 10 years and 8.5% at 15 years from diagnosis of WM, respectively. There was no difference in the 5-year cumulative probability of transformation in patients with WM diagnosed between 1996-2000 (2.1%), 2001-2005 (2.9%), 2006-2010 (2.7%) and 2011-2015 (3.8%), p=0.61.The disease characteristics, laboratory parameters and histology at transformation are outlined in Table 1. In patients with DLBCL histology (n=39), Revised-International Prognostic Index was calculable in 28 patients, with 50% (n=14), 46% (n=13) and 4% (n=1) of DLBCL belonging to poor, good and very good risk groups, respectively. For DLBCL histology, 18 patients were classifiable using Hans algorithm into germinal center B-cell (GCB) type (n=3, 17%) and non-GCB type histology (n=15, 83%). The median lines of therapy received prior to transformation for the entire cohort was 2 (range 0-9), with 5 (11%) patients not having received any therapy for WM before transformation. Number of lines of alkylator-based therapy used prior to transformation [median 1 line (range 0-4)] was comparable to that used in patients in whom WM did not occur [median 1, (range 0-6); p=0.78]. The median time-to-transformation from diagnosis of WM was 4.8 years (95% CI: 2.6- 6.8 years). Overall survival (OS) from transformed disease was 3.2 years (95% CI 1.1-3.9 years). The 10-year OS of patients with WM who transformed was lower (46%) compared to patients without transformation (60%) with a trend towards statistical significance (p=0.08), Figure 1. The MYD88L265P mutation status was available in 333 patients in the entire cohort (22/42 pts in the transformed cohort and 311/972 in the non-transformed cohort. Of the 22 patients in the transformed WM cohort, 13 (59%) exhibited MYD88WT genotype and 9 (41%) exhibited MYD88L265P genotype. The risk of transformation was higher in patients with MYD88WT status [Odds ratio 6.3 (95% CI: 2.6-15.5); p<0.0001]. Additionally, serum lactate dehydrogenase (LDH) was higher at diagnosis of WM in patients who transformed, Table 2. On multivariate analysis, MYD88WT status remained an independent predictor of disease transformation [p=0.003; odds ratio 10 (95% CI: 2.1-48)]. On univariate Cox proportional hazard analysis for identifying predictors of time-to-transformation, only MYD88WT mutational status was associated with shorter time-to-transformation with a 5-year transformation rate of 15.5 % for MYD88WT versus 2.6 % with MYDL265P mutated patients [risk ratio 6.2 (95% CI: 2.5-16.4); p<0.0001]. Treatment-related details in the transformed cases were available for 37 (90%) patients; R-CHOP was the most common (41%) frontline therapy for transformation; 33% patients underwent autologous stem cell transplantation for transformed disease during their disease course. Conclusion: Histological transformation is an uncommon event in WM but confers poorer survival. MYD88WT genotype is independently associated with histological transformation a shorter time-to- transformation in patients with WM. Disclosures Ansell: Trillium: Research Funding; Pfizer: Research Funding; LAM Therapeutics: Research Funding; Seattle Genetics: Research Funding; Affimed: Research Funding; Takeda: Research Funding; Celldex: Research Funding; Regeneron: Research Funding; Merck & Co: Research Funding; Bristol-Myers Squibb: Research Funding. Gertz:Apellis: Consultancy; Alnylam: Honoraria; spectrum: Consultancy, Honoraria; janssen: Consultancy; annexon: Consultancy; Prothena: Honoraria; Abbvie: Consultancy; Amgen: Consultancy; celgene: Consultancy; Teva: Consultancy; Medscape: Consultancy; Ionis: Honoraria; Research to Practice: Consultancy; Physicians Education Resource: Consultancy. Dingli:Millennium Takeda: Research Funding; Millennium Takeda: Research Funding; Alexion Pharmaceuticals, Inc.: Other: Participates in the International PNH Registry (for Mayo Clinic, Rochester) for Alexion Pharmaceuticals, Inc.; Alexion Pharmaceuticals, Inc.: Other: Participates in the International PNH Registry (for Mayo Clinic, Rochester) for Alexion Pharmaceuticals, Inc.. Witzig:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Dispenzieri:Celgene, Takeda, Prothena, Jannsen, Pfizer, Alnylam, GSK: Research Funding. Lacy:Celgene: Research Funding. Kumar:Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees; Novartis: Research Funding; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding. Kapoor:Takeda: Research Funding; Celgene: Research Funding.

Abstract Background: Axi-cel is a US FDA-approved, autologous anti-CD19 chimeric antigen receptor (CAR) T cell therapy for the treatment of patients with relapsed or refractory large B cell lymphoma with ≥ 2 prior systemic therapies. This report focuses on high-risk patient populations as well as long-term durability of response, and B cell recovery. Methods: In ZUMA-1, eligible patients with refractory large B cell lymphoma (diffuse large B cell lymphoma, primary mediastinal B cell lymphoma, transformed follicular lymphoma) underwent leukapheresis and received low-dose conditioning followed by a target dose of 2 × 106 anti-CD19 CAR T cells/kg (Neelapu and Locke et al. NEJM. 2017; NCT02348216). Outcomes in patients with double-expressor B cell lymphoma (MYC [≥ 40%] and BCL-2 [≥ 50%] protein expression by immunohistochemistry [IHC]) or high-grade B cell lymphoma (HGBCL), defined as double- or triple-hit (MYC+ and BCL2+ and/or BCL6+ by fluorescence in situ hybridization) or not otherwise specified (MYC- and > 70% Ki67 by IHC) were examined by independent pathology review. Exploratory analyses, including normal B cell levels in peripheral blood over time and frequency of use of safety interventions of interest, were also performed. A long-term follow-up analysis will be conducted with a data cutoff of August 11, 2018 for all 108 patients, including the HGBCL subgroup. Results: As of August 11, 2017, all 108 patients had at least 1 year of follow-up, with a median follow-up of 15.4 months. The objective response rate (ORR) was 82% with a complete response (CR) rate or 58%. The CR rate was 53% (29/55) in patients with disease refractory to ≥ 2 consecutive prior lines of therapy and 72% (18/25) in patients who had relapsed within 12 months after autologous stem cell transplantation. High-risk genetics were assessed in the 47 evaluable pre-treatment tumor samples: 37 patients (79%) had HGBCL or double-expressor B cell lymphoma and had an ORR of 89% (33/37) including a CR rate of 68% (25/37). Forty-two percent of patients overall had ongoing responses with a median follow-up of 15.4 months including 49% (18/37) of patients with high-risk genetics. To investigate the relationship between B cell recovery and ongoing response, B cell levels were assessed over time. Overall, of the 87 evaluable patients, 47% had no detectable B cells at baseline, and the remainder had levels close to or below the lower level of quantification of the assay. In patients with ongoing responses at 12 months post axi-cel infusion, 19 of the 35 (54%) patients with evaluable samples had detectable B cells at 12 months. This suggests B cell recovery in some patients with ongoing response as only 6 of 40 (15%) patients with evaluable samples had detectable B cells at 3 months after axi-cel infusion. Grade ≥ 3 cytokine release syndrome (CRS) and neurologic events (NE) were generally reversible and reported for 12% and 31% of patients, respectively. Tocilizumab (45%) and/or steroids (28%) were used for the management of CRS and NE. The use of vasopressors, dialysis, and intubation were minimal, used in only 17%, 3%, and 3% of patients, respectively. Thirty-four percent of patients (37/108) had either no CRS/NE (6%) or only Grade 1 CRS with (12%) or without (16%) Grade 1 NE. For these 37 patients, the median onset of CRS and NE was 2 and 7 days after infusion, respectively. Patients with Grade 0 - 1 CRS/NE had similar efficacy (ORR, 86%; CR, 65%) but lower peak/AUC CAR T cell levels vs the overall population. Updated safety and efficacy results will be presented with a minimum follow-up of 2 years and a median follow-up of 27.1 months. Conclusion: High rates of durable response were observed in patients with HGBCL and double-expressor B cell lymphoma, with approximately half of these patients (18/37) maintaining CR at ≥ 1 year. Efficacy in these high-risk populations was comparable to the overall patient population in ZUMA-1. At 12 months, B-cell recovery was observed in over half the patients with ongoing remission. About one-third of patients had only Grades 0 - 1 CRS/NE yet showed comparable efficacy with the overall patient population. High-grade CRS/NE were largely managed with tocilizumab and steroids with very low use of intensive or invasive interventions. Updated outcomes with a minimum of 2 years of follow-up will be presented. Disclosures Neelapu: Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Cellectis: Research Funding; Poseida: Research Funding; Merck: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Acerta: Research Funding; Karus: Research Funding; Bristol-Myers Squibb: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees; Unum Therapeutics: Membership on an entity's Board of Directors or advisory committees; Kite/Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Miklos:Adaptive Biotechnologies: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Pharmacyclics - Abbot: Consultancy, Research Funding; Kite - Gilead: Consultancy, Research Funding; Genentech: Research Funding; Janssen: Consultancy, Research Funding. Hill:Pharmacyclics: 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; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: 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; Pharmacyclics: 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; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees. Deol:Novartis: Consultancy; Kite Pharmaceuticals: Consultancy. Reagan:Seattle Genetics: Research Funding. Flinn:Agios: Research Funding; Forty Seven: Research Funding; Celgene: Research Funding; Calithera: Research Funding; Portola: Research Funding; Kite: Research Funding; Forma: Research Funding; Genentech: Research Funding; Verastem: Research Funding; BeiGene: Research Funding; Incyte: Research Funding; Seattle Genetics: Research Funding; Trillium: Research Funding; Janssen: Research Funding; Merck: Research Funding; TG Therapeutics: Research Funding; ArQule: Research Funding; Constellation: Research Funding; Infinity: Research Funding; Novartis: Research Funding; Gilead: Research Funding; Curis: Research Funding; Pharmacyclics: Research Funding; Verastem: Consultancy, Research Funding; Takeda: Research Funding; Pfizer: Research Funding. McSweeney:Kite, a Gilead Company: Honoraria, Membership on an entity's Board of Directors or advisory committees. Munoz:Alexion: Consultancy; Genentech: Consultancy, Honoraria; Juno: Consultancy, Honoraria; Pharmacyclics: Consultancy, Honoraria; Janssen: Consultancy; Kite: Consultancy, Honoraria, Speakers Bureau; Bayer: Consultancy, Speakers Bureau; Gilead: Speakers Bureau; Pfizer: Consultancy; Bristol-Myers Squibb: Consultancy. Siddiqi:Juno Therapeutics: Other: Steering committee. Herrera:Bristol-Myers Squibb: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; Seattle Genetics: Research Funding; Pharmacyclics: Consultancy, Research Funding; AstraZeneca: Research Funding; Gilead Sciences: Research Funding; Merck, Inc.: Consultancy, Research Funding; KiTE Pharma: Consultancy, Research Funding; Immune Design: Research Funding. Xue:Kite, a Gilead Company: Employment. Jiang:Kite, a Gilead Company: Employment. Bot:KITE: Employment. Rossi:KITE: Employment. Kim:Kite, a Gilead Company: Employment. Go:KITE: Employment. Locke:Cellular BioMedicine Group Inc.: Consultancy; Novartis Pharmaceuticals: Other: Scientific Advisor; Kite Pharma: Other: Scientific Advisor.

Abstract Introduction: Immunoglobulin light chain (AL) amyloidosis is associated with significant morbidity and mortality. Several models were developed to allow survival prediction, but head-to-head model comparison is lacking. Patients and Methods: Five prognostic models were compared: Mayo 2004; Mayo 2012; 2013 European modification of Mayo 2004 (where Mayo 2004 stage 3 is subdivided into 3 subgroups based on NT-proBNP at 8500 ng/L and systolic blood pressure at 100 mmHg); 2015 European modification of Mayo 2004 (where Mayo 2004 stage 3 is subdivided into 2 subgroups based on NT-proBNP at 8500 ng/L); and organ model (a model based on number of involved organs). All patients with available baseline data for the 5 models were included in this study (n=1005). Improvements in predictive accuracy of the various models were determined by calculating a net improvement in survival prediction for each pair of prognostic models. Net improvement was considered as the proportion where model A outperforms model B minus the proportion where model B outperforms model A. Results: For all models, there was increasing risk for death with increasing stage. The organ model was the least powerful system with a hazard ratio of 2.8 for ≥4 organs compared to 1 involved organ. The organ model was consistently outperformed by the other 4 systems. In the cohort as a whole, the biomarker models (Mayo 2004; Mayo 2012; European 2013; European 2015) were comparable in ability to predict survival (Figure). However, a slightly superior performance of the European 2013 modification of the Mayo 2004 system was seen over the Mayo 2004 system in the group as a whole (net improvement 4.1%, P=0.023) and when restricted to non-ASCT population (net improvement 6.3% P=0.014). The European 2015 modification performed slightly better than the Mayo 2004 system in the ASCT population (net improvement 3.4%, P=0.025). 1-year mortality was better predicted by the European models (net improvement 11-14%, P<0.05), while the Mayo 2012 had better survival prediction to all other biomarker models in 3-year landmark comparison (net improvement 7-9%, P<0.05). Conclusion: Using biomarker based staging is a clear improvement over the organ staging system. The different biomarker staging systems' abilities to predict for survival were relatively comparable, solidifying the importance of soluble cardiac biomarkers and free light chain measurement as prognosticators in AL amyloidosis. Mayo 2004-based models better predict for early death while Mayo 2012 model has a better prediction for long-term survival. Figure. Figure. Disclosures Gertz: Ionis: Honoraria; celgene: Consultancy; spectrum: Consultancy, Honoraria; janssen: Consultancy; Amgen: Consultancy; Abbvie: Consultancy; Medscape: Consultancy; annexon: Consultancy; Teva: Consultancy; Research to Practice: Consultancy; Apellis: Consultancy; Alnylam: Honoraria; Prothena: Honoraria; Physicians Education Resource: Consultancy. Lacy:Celgene: Research Funding. Dingli:Millennium Takeda: Research Funding; Millennium Takeda: Research Funding; Alexion Pharmaceuticals, Inc.: Other: Participates in the International PNH Registry (for Mayo Clinic, Rochester) for Alexion Pharmaceuticals, Inc.; Alexion Pharmaceuticals, Inc.: Other: Participates in the International PNH Registry (for Mayo Clinic, Rochester) for Alexion Pharmaceuticals, Inc.. Kapoor:Celgene: Research Funding; Takeda: Research Funding. Russell:Vyriad: Equity Ownership. Kumar:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding. Dispenzieri:Celgene, Takeda, Prothena, Jannsen, Pfizer, Alnylam, GSK: Research Funding.

Abstract Introduction: Light chain burden in light chain (AL) amyloidosis is often low, making accurate response assessment challenging. Methods: AL amyloidosis patients achieving very good partial or complete response to first line therapy and had serial sFLC studies during and after completion of therapy were included (n=396). Involved free light chain (iFLC), difference in involved-to-uninvolved free light chains (dFLC) and sFLC ratio (sFLCR) were assessed at the end of first line therapy and at nadir iFLC. Survival analysis was done using the Kaplan-Meier method. Hematological progression-free survival (hemPFS) was defined as the time from diagnosis until hematological progression or death, where patients known to be alive and progression-free at the end of follow-up were censored. Hematological progression was defined according to consensus criteria or upon initiation of second line therapy, whichever came first. Results: The median iFLC and dFLC at the end of therapy was 1.7 mg/dL and 0.5 mg/dL, respectively. sFLCR normalization occurred in 70% of patients. iFLC ≤2 mg/dL and dFLC ≤0.5 mg/dL were associated with a longer hemPFS compared to their counterparts (Figure). Only iFLC ≤2 mg/dL was associated with a significantly longer overall survival (Figure). sFLCR normalization did not predict hemPFS or overall survival. Organ response was predicted by iFLC ≤2 mg/dL and dFLC ≤0.5 mg/dL (Table), with best discrimination seen with iFLC ≤2 mg/dL. Organ response was not predicted by sFLC normalization (Table). The median nadir iFLC was 1.4 mg/dL and was reached 3.9 months from the end of therapy, longer in transplanted patients compared to patients treated with non-transplant regimens (7.3 vs 1.8 months, respectively; P<0.001). iFLC ≤2 mg/dL at the completion of therapy and nadir iFLC reached >12 months from the end of therapy were favorable predictors of hemPFS/OS in a multivariate analysis. Conclusion: iFLC at the end of first line therapy better predicts for organ response and survival than dFLC among deep responders. Normalization of sFLCR does not predict for organ response or survival and should not be used as measure of therapeutic efficacy. Figure. Figure. Disclosures Dispenzieri: Celgene, Takeda, Prothena, Jannsen, Pfizer, Alnylam, GSK: Research Funding. Dingli:Alexion Pharmaceuticals, Inc.: Other: Participates in the International PNH Registry (for Mayo Clinic, Rochester) for Alexion Pharmaceuticals, Inc.; Alexion Pharmaceuticals, Inc.: Other: Participates in the International PNH Registry (for Mayo Clinic, Rochester) for Alexion Pharmaceuticals, Inc.; Millennium Takeda: Research Funding; Millennium Takeda: Research Funding. Kapoor:Celgene: Research Funding; Takeda: Research Funding. Russell:Vyriad: Equity Ownership. Kumar:Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding. Gertz:Alnylam: Honoraria; celgene: Consultancy; Ionis: Honoraria; Abbvie: Consultancy; annexon: Consultancy; janssen: Consultancy; spectrum: Consultancy, Honoraria; Research to Practice: Consultancy; Medscape: Consultancy; Apellis: Consultancy; Teva: Consultancy; Amgen: Consultancy; Prothena: Honoraria; Physicians Education Resource: Consultancy.

Abstract Aims: Autologous stem cell transplantation (ASCT) is an important component in the treatment of newly diagnosed multiple myeloma (MM). However, relapse following ASCT is considered almost inevitable, with a median time to progression (TTP) of approximately 23-26 months (without maintenance) and 40-46 months (with maintenance)(Attal MA et al. N Engl J Med 2012; 366:1782-1791; McCarthy PM et al. N Engl J Med 2012; 366:1770-1781). However, some patients can experience a prolonged period of remission with ASCT. The purpose of this study was to identify and characterize patients who have an exceptional response to upfront ASCT without maintenance therapy, and to determine the frequency of relapse in such patients. Methods: We searched the Mayo Clinic Multiple Myeloma bone marrow transplant database for patients who were diagnosed with MM between Aug 1, 1988 to Jan 3, 2006, and underwent ASCT within 12 months of initial diagnosis. For the purposes of this study, we defined exceptional responders as patients who were free of progression for 96 months or more, which is 2-3 fold more than the median TTP expected in this population. Since maintenance therapy was not standard of care at the time, only a small minority (6) of patients with prolonged TTP had received maintenance therapy; these patients were excluded since the study was focused on exceptional response with ASCT alone. One patient who had a tandem autologous transplant was excluded. Results: 509 patients underwent transplant during the study period. Of those, 46 (9%) met criteria for exceptional response. Twenty seven (59%) were female, 19 (41%) were male. Median age was 57.28 years, range, 31.9-73.0. Of 45 patients with response data available, the best response status was complete response or better in 32 patients (73.3%), VGPR in 4 patients (8.9%), and PR in 8 patients (17.7%). FISH data were available during the disease course for 41 patients. Of these, the majority, 28 patients (68.3%), had no abnormalities detected by the probes used; 3 patients (7.3%) had high risk cytogenetics (t(4;14) in 2 patients and t(14;16) in one patient) , 4 (9.8%) had trisomies; 6 patients had other isolated abnormalities. At last follow up, 23 patients have progressed (50%); 14 (30.4%) have died, including one who died without progression to MM. The median overall survival from time of diagnosis of the exceptional responders was 18.5 years, range 9.2-22 years. From the landmark time of 96 months, the median TTP was 6.2 years, range, 0.4-10.6 years (Figure 1); No plateau was seen in the TTP curve. From the landmark time of 96 months, the median OS was 10.5 years, range, 0.4-14 years. Conclusions: We conclude that approximately 10% of patients with newly diagnosed myeloma have an exceptional response to a single ASCT without maintenance therapy. These patients have a remarkable overall survival, both from diagnosis and from the landmark time point where they are classified as having achieved an exceptional response. Although TTP from the landmark time point is excellent, with median TTP of 6.2 years, there appears to be no plateau in the curve indicating ongoing risk of relapse despite a prolonged period of disease stability. Exceptional responders tended to have normal FISH studies (likely an indicator of responsive, low-tumor burden disease), and nearly 20% achieved this state despite not attaining a complete response. Figure. Figure. Disclosures Gertz: Research to Practice: Consultancy; Apellis: Consultancy; spectrum: Consultancy, Honoraria; Medscape: Consultancy; celgene: Consultancy; janssen: Consultancy; Teva: Consultancy; Abbvie: Consultancy; annexon: Consultancy; Ionis: Honoraria; Alnylam: Honoraria; Prothena: Honoraria; Amgen: Consultancy; Physicians Education Resource: Consultancy. Kumar:KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; Novartis: Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. Dispenzieri:Celgene, Takeda, Prothena, Jannsen, Pfizer, Alnylam, GSK: Research Funding. Dingli:Millennium Takeda: Research Funding; Millennium Takeda: Research Funding; Alexion Pharmaceuticals, Inc.: Other: Participates in the International PNH Registry (for Mayo Clinic, Rochester) for Alexion Pharmaceuticals, Inc.; Alexion Pharmaceuticals, Inc.: Other: Participates in the International PNH Registry (for Mayo Clinic, Rochester) for Alexion Pharmaceuticals, Inc.. Russell:Vyriad: Equity Ownership. Kapoor:Takeda: Research Funding; Celgene: Research Funding.

Abstract Introduction Recent advances in the understanding of the WM pathobiology led to the expansion of our therapeutic options in this disease. A number of targeted drugs are either available or under investigation and are poised to change the chemo-immunotherapy paradigm in the treatment of WM. Now more than ever, an individualized treatment approach for patients with WM is possible, where patient characteristics and preferences can be matched by different treatment goals and side effect profiles. While deep responses have been associated with longer disease-free survival in other hematologic malignancies, data on patients with WM are sparse. We report the impact of depth of response in disease-free and overall survival (OS) in WM. Methods WM patients consecutively seen at Mayo Clinic between 01/1998 and 12/2016 were reviewed for response to therapy and disease burden. The best response achieved after the treatment of interest (TOI) was classified using the IWWM-7 Response Criteria. The included TOI were: BR, DRC, BDR and high-dose chemotherapy followed by ASCT. All time-to-event analyses were performed from the TOI initiation date using the Kaplan-Meier method and the log-rank test. A landmark analysis from the date-of-best response was also performed for OS to prevent immortal-time bias. Univariate and multivariate analyses of progression-free survival (PFS) and time-to-next therapy (TTNT) were performed using the Cox regression method. Results A total of 181 patients had disease response assessed after the TOI. Baseline characteristics at time of diagnosis are summarized in table 1. The median follow up from TOI was 3.8 years (95% CI: 3-4), the majority of patients received TOI as salvage therapy [n=112 (63%); median 2nd line (rage 1-11)]. Best response rates with the corresponding 5-year PFS and TTNT are summarized in table 2. The median OS from TOI was longer in patients who achieved at least a PR [median 7.2 years (95% CI: 5-NR) vs 3.7 years (95% CI: 1.6-NR), p=0.01]. A trend towards a longer OS was also seen with deeper responses (PR or better) achieved with frontline therapy [median 5.8 years (95% CI: 5.8-NR) vs 3.4 years (95% CI: 1.6-NR), p=0.24]. Figure 1 shows the correlation between deeper responses with PFS and TTNT. Among patients achieving a PR or VGPR, those with a normal FLC ratio post TOI demonstrated a longer PFS and TTNT [PFS: median NR (95% CI: 3.4-NR) vs 4.9 years (95% CI: 2.8-8.7), p=0.01; TTNT: median NR (95% CI: 3.5-NR) vs 5.2 years (95% CI: 4.2-9.4), p=0.04], figure 2. In a multivariate analysis including normal FLC ratio, normal IgM level and minimal BM involvement (<5%) post TOI, normal FLC ratio remained an independent prognostic factor for longer PFS and TTNT. Similar trends were seen when considering treatment naïve and relapsed/refractory patients independently (data not shown). Discussion Our results not only suggest an association between depth of response with PFS and TTNT, but also with OS in patients with WM. A normal FLC ratio (not part of the IWWM-7 response criteria) seems to predict a longer disease-free interval in patients achieving a PR or VGPR. Disclosures Gertz: Ionis: Honoraria; Apellis: Consultancy; annexon: Consultancy; Prothena: Honoraria; janssen: Consultancy; Physicians Education Resource: Consultancy; Alnylam: Honoraria; Teva: Consultancy; spectrum: Consultancy, Honoraria; Medscape: Consultancy; celgene: Consultancy; Research to Practice: Consultancy; Amgen: Consultancy; Abbvie: Consultancy. Kapoor:Takeda: Research Funding; Celgene: Research Funding. Ailawadhi:Amgen: Consultancy; Janssen: Consultancy; Takeda: Consultancy; Pharmacyclics: Research Funding; Celgene: Consultancy. Reeder:Affimed: Research Funding. Witzig:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Dispenzieri:Celgene, Takeda, Prothena, Jannsen, Pfizer, Alnylam, GSK: Research Funding. Lacy:Celgene: Research Funding. Kumar:Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. Ansell:Seattle Genetics: Research Funding; Celldex: Research Funding; Bristol-Myers Squibb: Research Funding; LAM Therapeutics: Research Funding; Trillium: Research Funding; Pfizer: Research Funding; Takeda: Research Funding; Merck & Co: Research Funding; Affimed: Research Funding; Regeneron: Research Funding.