Gertz, Morie A.

Abstract Background Waldenstrom macroglobulinemia (WM) is an IgM-associated lymphoplasmacytic lymphoma, first described over seven decades ago. Although WM is typically a disease of the elderly, with a median age at diagnosis of ~ 67 years, approximately 10% of patients are ≤50 years (y) of age at diagnosis. Data for young patients are sparse and the few available studies demonstrate inconsistent findings, with potential overestimation of survival owing to inclusion of patients with smoldering WM. In this case-control study, we evaluate outcomes, prognostic features and impact of changing therapies in a large cohort of young symptomatic WM patients compared to matched older patients seen over the course of the past five decades. Methods The medical records of all WM patients seen consecutively at Mayo Clinic from 01/1960 to 10/2013 were reviewed. Of 1181 patients, 140 (11.8%) were ≤ 50 y of age at diagnosis. A cohort of patients 65 y or older at diagnosis, matched 1:1 by the time of diagnosis, served as the control population. The patients were divided into 3 groups based on the timing of initiation of therapy: Group 1 (1960-1977), Group 2 (1978-1995) and Group 3 (1996-2013). The baseline characteristics were compared. Initiation of frontline therapy was used for all time-to-event analysis using the Kaplan Meier method. Results Younger patients were more likely to present with adenopathy and splenomegaly, have higher IgM levels and hyperviscosity symptoms (Table 1). The median follow-up from the frontline therapy was similar (10.7 y vs. 10 y for the control population). At the time of analysis, 91% of the deaths for the younger cases were WM-related compared to 58% in the control arm (p=0.0001). Younger patients had a better OS with a median disease-specific survival (DSS) of 15.6 y (95% CI: 13-21; 10-y OS of 77%) vs. 11 y (95% CI: 7.8-12; 10-y OS of 51%) for the older patient (p=0.0003). Among the young patients, there was no difference in the median DSS across the 3 groups (p=0.42). However, the median DSS for the control group incrementally improved (p=0.02) over the 3 time periods (Table 1). In the younger patients, no improvement in DSS was noted with the use of either frontline rituximab-based therapy compared to non-rituximab based regimens [median NR (95% CI: 7.6-NR) vs. 15.8 y (95% CI: 13-22) with other regimens, p=0.30], or frontline chlorambucil-based compared to non-chlorambucil based regimens [median 16 y (95% CI: 12-22) vs 15.6 y (95% CI: 12-NR) with other regimens, p=0.73]. In the control group, however, there was significant difference in DSS among patients who received frontline rituximab-based compared to non-rituximab based regimens [median NR (95% CI: 8.3-NR) vs 9.1 y (95% CI: 5.6-12) with other regimens, p=0.04], or frontline chlorambucil-based vs non-chlorambucil based regimens [8 y (95% CI: 5-12) vs 12.3 y (95% CI: 11-NR) in other regimens; p=0.001]. Conclusion Striking differences in presentation are evident in young WM patients compared to their older counterparts. The incorporation of rituximab to the previously existing anti-WM regimens and the transition to non-chlorambucil based regimens has resulted in substantial survival gains in the older WM population over the past five decades. However, such improvement in outcome has not yet been observed in the young patients. The majority of younger patients, despite a protracted disease course, succumb to their disease. Disclosures Ansell: BMS, Seattle Genetics, Merck, Celldex and Affimed: Research Funding. Ailawadhi:Pharmacyclics: Consultancy; Novartis: Consultancy; Amgen Inc: Consultancy; Takeda Oncology: Consultancy. Reeder:Novartis: Research Funding; Celgene: Research Funding; BMS: Research Funding; Millennium: Research Funding. Kumar:Kesios: Consultancy; Janssen: Consultancy, Research Funding; Sanofi: Consultancy, Research Funding; AbbVie: Research Funding; BMS: Consultancy; Onyx: Consultancy, Research Funding; Glycomimetics: Consultancy; Millennium: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Noxxon Pharma: Consultancy, Research Funding; Array BioPharma: Consultancy, Research Funding; Skyline: Honoraria, Membership on an entity's Board of Directors or advisory committees. Dispenzieri:Alnylam: Research Funding; Celgene: Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Prothena: Membership on an entity's Board of Directors or advisory committees; GSK: Membership on an entity's Board of Directors or advisory committees; pfizer: Research Funding; Jannsen: Research Funding. Kapoor:Celgene: Research Funding; Takeda: Research Funding; Amgen: Research Funding.

Abstract Abstract 3469 Introduction: Stem cell transplantation is important in the management of multiple myeloma. In the United States, the standard of care is administration of growth factors to accelerate neutrophil recovery after stem cell transplant. The need for growth factors after transplant has not been investigated recently. Patients: We analyzed a cohort of 166 patients at our institution who underwent autologous transplant for multiple myeloma without receiving growth factors after transplant and compared them with 498 patients who received standard filgrastim beginning on posttransplant day 5. TABLE Results: A neutrophil count of 500/μL was achieved in a median of 12.5 days in patients receiving growth factor, compared with 13.5 days in those not receiving growth factor (P<.001) Fig 1. Platelet engraftment was identical (median, 14.5 days; P=.12) in both groups, despite a lower median number of CD34+ cells infused in patients who did not receive growth factors. Incidence of nonstaphylococcal bacteremia was identical in both groups. The median hospital stay was 3.5 days shorter in the group not receiving growth factor. Bacteremia impacted platelet but not neutrophil engraftment. Figure 2 Conclusion: It is feasible and reasonable to perform autologous stem cell transplant for multiple myeloma without administering growth factors. Estimated savings would be $4,600 for each transplanted patient. Growth factor administration is not required for a safe outcome and decreases the number and severity of some of the fluid-related complications after transplant such as acute respiratory distress syndrome, allergic reactions, alveolar hemorrhage, and rarely splenic rupture. Disclosures: Gertz: Celgene: Honoraria; Millenium: Honoraria, Membership on an entity's Board of Directors or advisory committees. Lacy:Celgene: Research Funding. Dispenzieri:Celgene: Honoraria, Research Funding; Binding Site: Honoraria. Kumar:Celgene: Consultancy, Research Funding; Millennium: Research Funding; Merck: Consultancy, Research Funding; Novartis: Research Funding; Genzyme: Consultancy, Research Funding; Cephalon: Research Funding.

Abstract Background Bendamustine/rituximab (BR) and dexamethasone/rituximab/cyclophosphamide (DRC) combination therapy are acceptable options for the treatment of WM, both in the frontline or salvage setting. Prospective data, however, are only available in treatment-naïve (TN) WM patients, and no direct comparison between BR and DRC has been reported. We compared outcomes of BR and DRC in relapsed/refractory (R/R) and TN WM patients seen at a single institution. Methods Records of WM patients seen consecutively at Mayo Clinic from 01/2007 to 12/2014 were reviewed. The MYD88L265P status, as assessed by AS-PCR, was recorded when available. The data obtained from symptomatic patients treated with DRC or BR were analyzed. The time-to-event analyses were performed from DRC or BR therapy using the Kaplan-Meier method. We used the Consensus criteria (6th International Workshop) for response assessment. Results Of 160 WM patients, 60 patients received BR (73% in R/R setting) and 100 patients received DRC (50% in R/R setting). In the R/R population, BR was the 2nd line (range 2-11) therapy in 47% of patients, while DRC was 2nd line (range 2-8) in 58% of patients. Rituximab monotherapy was the only prior line of therapy in 8 (20%) patients in the BR group and 20 (40%) in the DRC group (p=0.66). Baseline characteristics were similar in patients treated with BR or DRC (Table 1). Six patients received both BR and DRC during their disease course and overlapped between the 2 cohorts. Among the previous untreated patients, the median IgM levels decreased from 3,785 mg/dL to 724 mg/dL (p=0.0001) at best response with BR, while it decreased from 4,130 mg/dL to 1,250 mg/dL (p=0.001) with DRC. The median time to best response was 6.1 (1-25) months in the BR group and 11 (0.5-47) months in the DRC group (p=0.13). For patients treated with BR, the overall response rate (ORR) was 93% [VGPR 29% (n=4), PR 57% (n=8), MR 7% (n=1)]. One patient (7%) had progressive disease. For patients treated with DRC, ORR was 96% [VGPR 17% (n=8), PR 70% (n=32), MR 9% (n=4)]. One patient (4%) achieved SD. Median follow up in the BR and DRC groups were similar (30 months). The 2-year progression-free survival (PFS) was 88% and 61% in the BR and DRC groups, respectively (p=0.08). The 2-year time-to-next therapy (TTNT) was 88% and 76% in the BR and DRC groups, respectively (p=0.35). Median PFS, TTNT and disease specific survival (DSS) were not reached with either regimen. In the R/R setting, the median IgM levels decreased from 3,880 mg/dL to 659 mg/dL (p=0.0001) at best response with BR, and from 3,870 mg/dL to 1,846 mg/dL (p=0.001) with DRC. The median time to best response was similar [7 (1-39) months with BR and 7 (0.5-28) months with DRC (p=0.77)]. For patients treated with BR, ORR was 95% [CR 3% (n=1), VGPR 38% (n=14), PR 41% (n=15), MR 13% (n=5)]. Two patients (5%) had progressive disease. With DRC, the ORR was 87% [VGPR 4% (n=2), PR 64% (n=30), MR 19% (n=9)]. Four patients (9%) achieved SD and 2 patients (4%) had progressive disease. Median follow up from BR was 32 months and 51 months from DRC (p=0.24). The 2-year PFS was 66% and 53% in the BR and DRC groups, respectively (p=0.08). The 2-year TTNT was 75% and 68% in the BR and DRC groups, respectively (p=0.24). The median DSS in the BR group was 69 months (95% CI: 65-69) and NR (95% CI: NR-NR) in the DRC group (p=0.57). The proportion of patients with R/R disease was significantly higher in the BR cohort (Table 1). In a bivariate analysis of the entire cohort for PFS, incorporating the setting (TN vs. RR) and the regimen involved (BR vs. DRC), the latter emerged as a significant factor (hazard ratio 0.52, p=0.019) in favor of BR. Time-to-event outcomes and response rates were similar in the MYD88L265P and MYD88WT patients. Grade ≥ 3 adverse events were neutropenia (12%), infections (7%) and nausea/vomiting (2%) with BR, and neutropenia (20%), thrombocytopenia (7%) and infections (3%) with DRC. Conclusions Although both DRC and BR regimens show activity and comparable toxicities, BR regimen shows a trend for superior PFS in WM patients, both in the TN and R/R setting. No difference was seen in TTNT. MYD88 L265P mutation status does not appear to impact activity of BR or DRC. Randomized controlled trial(s) are needed to confirm our findings. Disclosures Ailawadhi: Pharmacyclics: Consultancy; Novartis: Consultancy; Amgen Inc: Consultancy; Takeda Oncology: Consultancy. Ansell:BMS, Seattle Genetics, Merck, Celldex and Affimed: Research Funding. Reeder:Millennium: Research Funding; BMS: Research Funding; Novartis: Research Funding; Celgene: Research Funding. Dispenzieri:Jannsen: Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; pfizer: Research Funding; Prothena: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; Alnylam: Research Funding; GSK: Membership on an entity's Board of Directors or advisory committees. Kumar:Sanofi: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; AbbVie: Research Funding; Array BioPharma: Consultancy, Research Funding; BMS: Consultancy; Kesios: Consultancy; Glycomimetics: Consultancy; Skyline: Honoraria, Membership on an entity's Board of Directors or advisory committees; Noxxon Pharma: Consultancy, Research Funding; Millennium: Consultancy, Research Funding; Onyx: Consultancy, Research Funding; Celgene: Consultancy, Research Funding. Kapoor:Celgene: Research Funding; Takeda: Research Funding; Amgen: Research Funding.

Abstract Abstract 4518 Introduction: Autologous stem cell transplant (PBSCT) is an integral part of the management of Multiple Myeloma (MM). Available data suggest that the timing of PBSCT has no effect on overall outcome. Some patients currently opt to delay their transplant, especially in this era of proteosome inhibitors and iMIDs. In such patients the best time for stem cell collection is unknown. We conducted a retrospective study looking at early stem collection and storage compared to stem cell collection at the time of transplant in patients who opt to be transplanted at a later date. Method: All patients who had PBSCT performed more than one year from the time of diagnosis were reviewed. Two groups of interest were then evaluated. Early collection (ET): those who had stem cells collected within 6 months of diagnosis, and Late collection (LT): those who had stem cells collected more than 1 year from diagnosis and within 3 months of PBSCT. Results: Table 1 shows some patient characteristics. 334 patients were identified, ET (85) and LT (249). Gender distribution, Durie Salmon stage, immunoglobulin subtype and cytogenetic abnormalities were similar in both groups. The LT group was older 60 yrs compared to ET 56.6 yrs, P=0.02. More patients in the ET (77%) group were mobilized with cyclophosphamide compared to LT (51%) p<0.0001. Stem cell yield was similar in both groups 9.26 × 10(6) CD34/kg in ET and 8.19 × 10(6) in LT, P=0.16. Median number of collections was 3 in both. More patients in the LT (67%) received Melphalan 200 mg/m2 conditioning compared to ET (59%) p=0.03. Neutrophil engraftment occurred at day + 11 ET and +12 (LT) p<0.0001. ET patients achieved platelet engraftment on day + 13 compared to + 15 (LT) p=0.002. Complete response rates were similar 30% (ET) and 34% (LT). Duration of response after PBSCT was not different 12.6 months (ET) and 11.6 months (LT). Median overall survival from diagnosis was 70.5 months (ET) and 74.5 months (LT) p=0.5. Similarly there was no difference in overall survival post PBSCT 33.5 month (ET) and 32.2 months (LT). Conclusion: Stem cell collection and storage early in the disease course of multiple myeloma results in early engraftment compared to stem cell collection at the time of transplant in patients who opt for a delayed transplant. More studies looking at cost analysis will however be need to determine the cost effectiveness of early versus late stem cell collection. Disclosures: Dispenzieri: Celgene: Honoraria, Research Funding; Binding Site: Honoraria. Kumar:Celgene: Consultancy, Research Funding; Millennium: Research Funding; Merck: Consultancy, Research Funding; Novartis: Research Funding; Genzyme: Consultancy, Research Funding; Cephalon: Research Funding. Gertz:Celgene: Honoraria; Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Abstract BACKGROUND: Necrobiotic Xanthogranuloma (NXG) is a rare chronic granulomatous disorder of the skin associated with monoclonal gammopathies (MG). Due to its rarity, data on response to various therapies are largely limited to single case reports or small case series. Hence, we described the clinical features in patients with NXG and MG as well as their subsequent disease course and response to treatment. METHODS: This was a retrospective study evaluating 35 patients with NXG and coexisting MG from 1994-2015 who were evaluated in the Hematology Outpatient Clinic at the Mayo Clinic, Rochester. All patients had a biopsy proven diagnosis of NXG with the concurrent presence of a serum monoclonal gammopathy. RESULTS: The median age at diagnosis was 56 years (range: 26-88). Most patients had a plasma cell dyscrasia (28 MGUS; 5 Smoldering myeloma) while 2 had chronic lymphocytic leukemia. Themost common monoclonal (M) protein was IgG kappa (60%). The median M-spike was 1.1 g/dL (range: 0-3). The most common site of NXG was periocular (66%). All patients received treatment, with over half requiring >3 different lines of treatment. The treatments were heterogeneous and included excision, intra-lesional injection, radiotherapy as well as systemic treatment. The types of systemic treatment used and clinical response are reported in Table 1. The median follow up was 46 months (range: 4-234) and the median survival was not reached but at the time of analysis 80% were still alive. At last follow-up, 80% of patients had signs of either clinical improvement or stable skin disease. Eight patients (23%) had disease progression to multiple myeloma at a median of 67 months (Range: 21 - 107). CONCLUSIONS: We report the clinical findings and treatment outcomes of one of the largest series of patients with NXG associated with MG. The clinical course is generally indolent but malignant transformation is not uncommon. Cutaneous objective responses can be achieved with various systemic agents used in the treatment of lymphoproliferative malignancies. Table 1. Treatment Types and Clinical Response Rates Treatment No of patientsA Clinical Benefit Rate B Response rateC Chemotherapy - Chlorambucil +/- Steroids - Melphalan/Steroids - Cytoxan/Steroids - Cladribine - Vincristine/doxorubicin/dexamethasone - High dose therapy with stem cell rescue - Fludarabine/cyclophosphamide/rituximab 5 3 4 3 2 3 1 2/5 (40%) 0/3 (0%) 1/4 (25%) 1/3 (33%) 1/2 (50%) 2/3 (67%) 1/1 (100%) 1/5 (20%) 0/3 (0%) 0/4 (0%) 1/3 (33%) 0/2 (0%) 2/3 (67%) 1/1 (100%) Novel agents - Thalidomide +/- Steroids - Lenalidomide +/- Steroids - Bortezomib +/- Steroids - Bortezomib/Lenalidomide/Dexamethasone 11 14 4 1 5/11 (45%) 10/14 (71%) 2/4 (50%) 1/1 (100%) 4/11 (36%) 7/14 (50%) 1/4 (25%) 1/1 (100%) Intravenous immunoglobulin 4 3/4 (75%) 2/4 (50%) Systemic steroids alone 11 4/11 (36%) 4/11 (36%) Rituximab 6 2/6 (33%) 1/6 (17%) AntibioticsD 3 0/3 (0%) 0/3 (0%) ImmunosuppressantsE 6 1/6 (17%) 0/6 (0%) ANo of patients who underwent a particular therapy amongst the 35 patients in the study cohort. BClinical Benefit: Improvement or stable skin disease CResponse: Improvement in skin disease DAntibiotics: Fluoroquinolones, Tetracycline EImmunosuppressants: Cyclosporine, Methotrexate, Plaquenil Disclosures Kumar: Celgene, Millennium, Onyx, Novartis, Janssen, Sanofi: Research Funding; Celgene, Millennium, Onyx, Janssen, Noxxon, Sanofi, BMS, Skyline: Consultancy; Skyline, Noxxon: Honoraria.

Abstract Background: Ixazomib is an experimental, orally bioavailable, proteasome inhibitor that has demonstrated anti-tumor activity in relapsed multiple myeloma (MM). In the dose escalation studies, ixazomib was tolerated up to a dose of 5.5 mg given every week as a single agent, while a dose of 4 mg was utilized in the combination studies with lenalidomide. We undertook this study to examine the efficacy and tolerability of the two doses of ixazomib in combination with dexamethasone in patients with relapsed MM. Patients and methods: This was a randomized phase 2 study of two doses of ixazomib (4mg; Arm A or 5.5 mg; Arm B) given weekly for three weeks with a week off along with weekly dexamethasone (40 mg) in patients with relapsed MM, who are proteasome inhibitor na•ve (including bortezomib) or have received less than 6 cycles of therapy with bortezomib and had a PR or better with no progression at the time of discontinuation. The primary objective was to determine the confirmed overall response rate (>=PR); secondary objectives included progression free and overall survival. A total of 71 patients were accrued from February 2013 to April 2015; one patient was ineligible. Results: Baseline characteristics were similar in the two arms; median age across the study was 70 years (46-84); 53% were male. Median number of prior therapies was 4 (range 2-6); 90% of the patients had prior IMiDs, 70% had prior transplant and 29% had prior bortezomib. At a median follow up of 10 months, 17 (49%) and 19 (54%) of patients had disease progression in arms A and B respectively with 12 (34%) patients in each arm still continuing on treatment. All patients in each arm were evaluable for response; the overall response rates were 31% in arm A (95%CI: 17-49) and 51% (95%CI: 34-69) in Arm B. The depth of response, event free survival and overall survival are outlined in Table 1. Among the patients with no prior bortezomib exposure the response rates were 38% for Arm A and 52% for Arm B. The treatment was well tolerated with 2 patients in each arm discontinuing treatment for adverse events; there were no on study deaths. A grade 3 or higher AE that was at least possibly related to treatment was seen in 21% and 54% in Arms A and B respectively; with 15% and 37% hematologic and 6% and 29% non-hematologic AEs. The most common attributable toxicities encountered included fatigue, thrombocytopenia, diarrhea and nausea with more grade 3 toxicities among Arm B. Peripheral neuropathy, possibly related to ixazomib, was seen in 55% (only grade 1 or 2) in arm A and 43% (2 patients with grade 3) in Arm B. Toxicities led to dose reduction of ixazomib in 17% and 43% of patients in Arm A and B respectively; the median number of cycles administered were 5 (1-24) and 5 (1-22) respectively. Conclusions: Ixazomib in combination with dexamethasone was well tolerated with significant anti-myeloma activity in this group of patients with relapsed MM. Deep responses including stringent CR were observed. The higher dose of ixazomib appears to be associated with a higher response rate but with higher rate of adverse events requiring dose reductions. Table 1. Treatment outcome in all patients Arm B (4 mg) (N=35) Arm C (5.5 mg) (N=35) Response Rate 31% (95%CI: 17-49) 51% (95%CI: 34-69) No. of Responders 11 18 sCR 0 1 CR 1 0 VGPR 7 8 PR 3 9 MR 5 1 Median Overall Survival1 NA NA 6 Months 100% 100% Median Event Free Survival1,2 8.4 mos (95%CI: 4.3-13.2) 8.2 mos (95%CI: 3.8-16.3) %Event Free at 6 Months 60% (95%CI: 45-81) 60% (95%CI: 45-81) Median Duration of Response1 16.7 mos (95%CI: 9.3-22.0) 16.3 mos (95%CI: 7.0-20.1) Median Time to Response 1.1 mos (range: 0.8-3.6) 1.0 mos (range: 0.8-7.5) CI: confidence interval; mo: month; NA: not attained 1Kaplan Meier 2Event-free survival time is defined as the time from registration to the first of disease progression, death due to any cause, or subsequent treatment for multiple myeloma. Disclosures Kumar: Celgene: Consultancy, Research Funding; Sanofi: Consultancy, Research Funding; Skyline: Consultancy, Honoraria; Onyx: Consultancy, Research Funding; Novartis: Research Funding; Janssen: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; BMS: Consultancy.

Abstract Abstract 3468 Engraftment syndrome (ES) is a complication of hematopoietic stem cell transplantation classically characterized by fever, rash, diarrhea, weight gain and non-cardiogenic pulmonary edema. Renal failure has been observed but is not considered to be a major part of the syndrome. We have noted that acute renal failure (ARF) is common around the time of leukocyte engraftment in light chain amyloidosis (AL) patients after autologous stem cell transplant (ASCT). We suspect this is due to ES and this retrospective review was conducted to further study this entity. Data were collected from 377 AL patients who underwent ASCT from 7/1997 to 10/2009. Patients who experienced an elevation of serum creatinine (Scr) > 0.5 mg/dl within 4 days of leukocyte engraftment were selected. Patients who carried a diagnosis of ES were also included regardless of Scr elevation. Nephrotoxic insults were reviewed. Vitals were collected. Forty-one patients met criteria. Four patients were found not to have ES, 2 sepsis, 1 allergic interstitial nephritis (AIN), 1 acute cellular rejection. ES was noted in 37 (9.8%) patients, 2 presented with mainly pulmonary ES and 8 had both pulmonary and renal involvement. The degree of renal failure varied from mild and self-limited to severe and requiring dialysis. The renal failure is usually preceded by fever, rash, increasing edema, relative hypotension and low urine sodium (Figure 1). Treatment with glucocorticoids (60 mg/d) was successful in reversing the renal failure in most patients but those with pulmonary involvement required higher doses. Our study showed that ES presents more commonly with renal failure than pulmonary involvement in AL patients. Further complications may be prevented by early treatment with corticosteroids once infection is ruled out. Dosing depends on concurrent pulmonary findings. Distinguishing ES with AIN is difficult as presentations are similar but AIN will continue until the offending drug is removed while ES generally responds quickly to steroids alone. Figure 1. Figure 1. Disclosures: Dispenzieri: Celgene: Honoraria, Research Funding; Binding Site: Honoraria. Kumar:Celgene: Consultancy, Research Funding; Millennium: Research Funding; Merck: Consultancy, Research Funding; Novartis: Research Funding; Genzyme: Consultancy, Research Funding; Cephalon: Research Funding.

Abstract Abstract 2699 Myeloid differentiation factor 88 (MYD88) is an adaptor protein that plays a key role in mediating innate immune response. Upon activation of toll-like (TLRs) or IL-1b receptors, MYD88 activates a signaling cascade that culminates in activation of NF-kB and expression of proinflammatory genes. Activating mutations in MYD88 have been reported in non-Hodgkin's lymphoma (NHL) tumors, including diffuse large B cell and marginal zones lymphoma. The most common MYD88 mutation described thus far is a single base pair mismatch resulting in an amino acid switch from lysine to proline at position 265 (MYD88L265P). MYD88L265P functions as a constitutively active MYD88 protein resulting in dysregulated NF-kB and STAT3 signaling. This mutation has recently been reported to be present in lymphomoplasmacytic lymphoma/Waldenstrom macroglobulinemia (LPL/WM) at a high frequency, ∼ 90% (Xu et al, ASH, #261, 2011). The discovery of MYD88L265P in a high percentage of LPL/WM tumors, and other subtypes of NHL, provides the basis for the identification and targeting of MYD88 dependent pathways. Additionally, the ability of this mutation to drive NF-kB-mediated cytokine expression combined with our finding that LPL/WM patients have elevated serum cytokines suggests that the MYD88 mutation may play a significant role in LPL/WM pathogenesis. We first wanted to confirm the incidence of the MYD88L265P mutation in LPL/WM and other subtypes of indolent lymphoma. Using Sanger sequencing we found that 57% (n=58) of LPL, 4% of MALT (n=23), 5% of nodal marginal zone (n=34), and 6% of splenic marginal zone (n=34) lymphomas harbor the MYD88L265P mutation, with all but 1 case being heterozygous. When we specifically looked at the LPL cases with WM, we found that 70% of WM tumors have the MYD88L265P mutation. In a validation cohort of WM (n=41), we found a similar mutation rate of 68%. Additionally, the WM cell line MWCL1 and the IgM secreting cell line BCWM.1 also harbor the MYD88L265P mutation. The prevalence of the MYD88L265P mutation in NHL, specifically WM and LPL, suggests that it may be a novel driver of lymphoma pathogenesis and a potential therapeutic target. However, it is not yet clear if this mutation correlates with activation of signaling pathways, or cell growth and survival in LPL/WM. To address these questions we first explored the possibility that the MYD88 signaling pathway is constitutively active in cells that express MYD88L265P. Upon activation of TLRs or IL-1b receptors, MYD88 forms a homodiamer and recruits IRAK1/4 and TRAF6 into a complex resulting in association and phosphorylation of TAK1 followed by activation of NF-kB. Using three cell lines that express MYD88L265P (BCWM, MWCL1, and OCI-Ly3), we looked for complex formation of MYD88, IRAK1/4, TRAF6, and TAK1. Immunoprecipitation of either endogenous IRAK1 or TAK1 revealed constitutive association with both TRAF6 and MYD88. We also detected phosphorylation of TAK1, and taken together, these data suggest that the MYD88 pathway is activated in cells that harbor the MYD88L265P mutation. We next wanted to confirm the significance of the MYD88 pathway on lymphoma cell growth. Using our cell lines we tested the effect of IRAK1/4, TAK1, and NF-kB inhibitors on cell proliferation. All MYD88L265P expressing cell lines were sensitive to the TAK1 and NF-kB inhibitors in a dose dependent manner (0–10 uM), however, we only saw inhibition of cell proliferation with the IRAK1/4 inhibitor at the highest dose (10 uM) in the BCWM cell line. These data suggest that cell proliferation is dependent on the MYD88 signaling pathway, with some variation being detected between cell line models and inhibitors. Because the MYD88 pathway has also been shown to drive cytokine secretion we next tested the impact of the IRAK1/4, TAK1, and NF-kB inhibitors on expression of IL-10. Using drug doses that were shown to inhibit cell proliferation, but not impact survival, we found that all three inhibitors reduced the level of IL-10 secreted by each of cell lines. In summary, our data confirm the high incidence on the MYD88L265P mutation in LPL/WM, we find that the MYD88 signaling pathway is constitutively activated in cells the harbor the mutation, and we show that cell proliferation and cytokine secretion are dependent on MYD88 signaling targets. These studies highlight the biologic significance of the MYD88L265P mutation in LPL/WM and suggest that the MYD88 signaling pathway may be a novel therapeutic target. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 3572 High dose melphalan and autologous stem cell transplantation (ASCT) is an effective treatment for light chain amyloidosis (AL) but high treatment related mortality (TRM) limits its use. Both cardiac troponin T (cTnT) and N-terminal-pro-brain natriuretic peptide (NT-pro-BNP) are sensitive predictors of high risk patients. Aim of this study is to compare two models of TRM, one using cTnT and the other BNP. Patients who underwent ASCT between 7/1996 and 7/2009 at the Mayo Clinic were analyzed retrospectively. Variables were chosen for ease of measurement and reproducibility thus echocardiographic parameters were excluded. Each additional risk factor must contribute to a significant increase in TRM. Also, since NT-pro-BNP and cTnT are already highly associated with mortality, the other risk factors must be independent predictors. Univariate analysis revealed serum albumin, B-2-microglobulin, cTnT, NT-pro-BNP, and uric acid were associated with TRM while age, sex, alkaline phosphatase, serum creatinine, CRP, proteinuria were not (Table 1). Multivariate analysis showed albumin and uric acid were independent risk factors to cTnT and NT-pro-BNP (Table 2). Of the 412 patients, 347 (8.9% TRM) could be evaluated by the cTnT, albumin and uric acid (TAU) model and 282 (9.2%) TRM could be evaluated by the NT-pro-BNP, albumin, uric acid (BAU) model. Both models showed increasing TRM with additional risk factors beyond 1 risk factor (Table 3 and 4). Albumin and uric acid were found to be significant contributors in both models. Patients with elevated cTnT alone had a 0% TRM vs 23.4% if they had 1 additional risk factor, p = 0.03. Similarly, TRM was 3.7% in patients with elevated NT-pro-BNP alone but 18.0% if they had 1 other risk factor, p = 0.05. NT-pro-BNP and cTnT could not be used in the same model because cTnT becomes non-significant. Both models were superior to visceral organ involvement which had TRM of 5.3% with 1, 9.2% with 2 and 16.7% with 3 organ involvement. Both models were also predictive of overall survival (Figure 1 and Figure 1b). Our results show that these models show that albumin and uric acid with either cTnT or NT-pro-BNP can accurately predict TRM in AL patients undergoing ASCT. Multivariate analysis shows that the NT-pro-BNP containing model may be superior since cTnT loses it significance when added to the model. Our results suggest these models could be very helpful in identifying high risk patients not suitable for ASCT. Figure 1a Overall survival evaluated by Kaplan-Meier method on 347 patients using the TAU model. Mortality increased significantly with the number of risk factors, p < 0.001. Solid line represents patients with 0 risk factors, dotted line represents patients with 1 risk factor, dashed line represents those with 2 risk factors and dotted dashed line represent those with 3 risk factors. Figure 1a. Overall survival evaluated by Kaplan-Meier method on 347 patients using the TAU model. Mortality increased significantly with the number of risk factors, p < 0.001. Solid line represents patients with 0 risk factors, dotted line represents patients with 1 risk factor, dashed line represents those with 2 risk factors and dotted dashed line represent those with 3 risk factors. Figure 1b Overall survival evaluated by Kaplan-Meier method on 282 patients using the BAU model. Overall survival was significantly longer in patients with less risk factors, p < 0.001. Solid line represents patients with 0 risk factors, dotted line represents patients with 1 risk factor, dashed line represents those with 2 risk factors and dotted dashed line represent those with 3 risk factors. Figure 1b. Overall survival evaluated by Kaplan-Meier method on 282 patients using the BAU model. Overall survival was significantly longer in patients with less risk factors, p < 0.001. Solid line represents patients with 0 risk factors, dotted line represents patients with 1 risk factor, dashed line represents those with 2 risk factors and dotted dashed line represent those with 3 risk factors. Table 1. Patient characteristics Control TRM p-value N 318 29 Age 58 (25–73) 55 (35–75) 0.54 Sex (male) 58.2% 72.4% 0.13 Albumin (g/dl) 2.7 (0.8–4.4) 2.2 (0.8–3.7) 0.02 Alkaline phosphatase (U/L) 89 (28–1014) 86 (31–1394) 0.22 b2m (mg/ml) 2.6 (1.0–35.1) 3.2 (1.3–15.2) 0.007 NT-pro-BNP (pg/ml) 564 (12–35000) 1661 (21–35001) 0.03 CRP (mg/L) 0.3 (0.01–16.6) 0.3 (0.05–3.2) 0.34 cTnT (ng/ml) 0.01 (0–1.0) 0.03 (0.01–0.22) <0.001 Scr (mg/dl) 1.1 (0.4–12) 1.2 (0.8–2.3) 0.09 Proteinuria (g/d) 3.4 (0.01–35.4) 5.1 (0.1–20.5) 0.10 Uric acid (mg/dl) 6.2 (1–14.8) 7.5 (3.7–13.2) 0.02 Organ Involvement 1 94.7% 5.3% 0.04 2 90.7% 9.3% 3 83.3% 16.7% Table 2. Multivariate analysis using proportional hazard model cutoffs >Risk Ratio >p-value Model TAU cTnT 0.04 ng/ml 2.78 0.01 Albumin 3.3 g/dl 3.11 0.03 Uric acid 8.5 mg/dl 2.69 0.02 Model BAU NT-pro-BNP 1270 pg/ml 3.77 0.003 Albumin 3.3 g/dl 3.53 0.04 Uric acid 8.5 mg/dl 3.11 0.03 Table 3. Model of cTnT, albumin and uric acid TAU Risk Factors n TRM p-value Risk Ratio 0 69 2.9% 1 205 5.9% 0.33 2 61 16.4% 0.009 2.98 3 12 41.7% 0.05 8.52 Table 4. Model of NT-pro-BNP, albumin and uric acid BAU Risk Factors >n >TRM >p-value >Risk Ratio 0 28 0% 1 161 5.6% 0.20 2 82 14.6% 0.02 2.7 3 11 45.5% 0.01 10.8 Disclosures: Kumar: Celgene: Consultancy, Research Funding; Millennium: Research Funding; Merck: Consultancy, Research Funding; Novartis: Research Funding; Genzyme: Consultancy, Research Funding; Cephalon: Research Funding. Dispenzieri:Celgene: Honoraria, Research Funding; Binding Site: Honoraria. Lacy:Celgene: Research Funding.

Abstract Background: Cytogenetic evaluation, especially using fluorescence in situ hybridization (FISH), at the time of diagnosis is essential for initial risk stratification and the employment of risk-adapted treatment strategies in multiple myeloma. Little is known about the occurrence and prognostic significance of cytogenetic evolution during follow up. Methods: We studied 433 patients who were diagnosed with multiple myeloma between January 2000 and December 2011 and had at least two FISH evaluations at Mayo Clinic Rochester, including the diagnostic specimen. Bone marrow aspirates were evaluated for deletions, monosomies, trisomies, and tetrasomies using chromosome- or centromere-specific FISH probes. IGH rearrangements were evaluated using an IGH break-apart probe and up to five potential partners (FGFR3, CCND1, CCND3, MAF, and MAFB). Cytogenetic evolution was defined as a new deletion, monosomy, trisomy, tetrasomy, or translocation during follow up. Multivariable-adjusted logistic regression models were used to assess the associations between the parameters of interest and the presence of cytogenetic evolution in follow-up specimens. Multivariable-adjusted Cox proportional hazards models were used to assess the effect of cytogenetic evolution on overall survival. All models were adjusted for sex, age, the presence of high-risk FISH abnormalities, and the number of abnormalities at the time of diagnosis. Likelihood ratio tests were used to assess the goodness of fit of nested models. The χ2 or Fisher's exact test was used to assess the distribution of cytogenetic abnormalities in subgroups. Results: The median age at diagnosis was 60 years (32 - 82), 264 (61%) of the patients were male. The median overall survival for the entire cohort was 7.0 years (6.2 - 7.8). At the time of diagnosis, 150 (35%) and 57 (13%) of the 433 patients presented with a hyperdiploid karyotype and cytogenetic high-risk abnormalities, respectively. Independent of each other, the presence of a translocation at the time of diagnosis was associated with decreased odds of cytogenetic evolution during follow up (OR 0.39, 95% CI 0.24 - 0.63, p < 0.001) while the presence of at least one trisomy or tetrasomy at the time of diagnosis was associated with increased odds (OR 2.53, 95% CI 1.37 - 4.70, p = 0.003). A greater proportion of patients presenting with a hyperdiploid karyotype experienced cytogenetic evolution during follow up. Those patients more frequently evolved additional trisomies and tetrasomies, while translocations were more common in those presenting with a non-hyperdiploid karyotype (Table 1). The development of additional abnormalities during the three years following diagnosis (compared to no new abnormalities) was associated with increased subsequent mortality in those who survived at least three years (HR 3.22, 95% CI 1.82 - 5.68, p < 0.001). Including the time between first and last cytogenetic evaluation as a covariate did not significantly change the parameter estimates or improve model fit (p = 0.727). Conclusions: Demographics, risk profile, and overall survival of this cohort reflect the fact that patients had to survive long enough to undergo repeated cytogenetic evaluation. Hyperdiploid and non-hyperdiploid genotypes were associated with distinct behavior regarding cytogenetic evolution during follow up. The identification of cytogenetic evolution was an adverse prognostic factor in those who survived at least three years after diagnosis. These findings emphasize the importance of the dynamics of the underlying clonal disease process for accurate risk assessment and suggest that selected subgroups of patients may benefit from risk stratification during follow up. Table 1. Cytogenetic evolution during follow up in 433 patients with multiple myeloma stratified by karyotype at the time of diagnosis Hyperdiploid (n = 150) Non-hyperdiploid (n = 283) p New abnormality 76 (51%) 108 (38%) 0.012 New monosomy 8 (5%) 24 (8%) 0.243 New trisomy 48 (32%) 55 (19%) 0.004 New tetrasomy 37 (25%) 27 (10%) < 0.001 New deletion 17 (11%) 27 (10%) 0.557 New translocation 1 (1%) 11 (4%) 0.065 Most common new abnormality [type (percent of type in each group)] Monosomy mono(13) (75%) mono(13) (62%) Trisomy tri(11) (22%) tri(3) (22%) Tetrasomy tetra(15) (48%) tetra(15) (30%) Deletion del(17p) (79%) del(17p) (63%) Translocation t(11;14) (100%) t(11;14) (36%) Data are given as count (percent) unless denoted otherwise. Disclosures Binder: American Society of Hematology: Research Funding. Kumar:AbbVie: Research Funding; Onyx: Research Funding; Sanofi: Research Funding; Celgene, Millenium, Sanofi, Skyline, BMS, Onyx, Noxxon,: Other: Consultant, no compensation,; Skyline, Noxxon: Honoraria; Millenium/Takeda: Research Funding; Janssen: Research Funding; Celgene: Research Funding.