Rajkumar, S. Vincent

Abstract Introduction: Multiple myeloma (MM) accounts for about 20% of deaths from hematological cancers and remains incurable despite conventional and high-dose chemotherapy. Two phase III trials in patients with relapsed or refractory MM (MM-009 and MM-010) showed that lenalidomide combined with dexamethasone resulted in significantly improved response rates and significantly prolonged median time to progression (TTP) and overall survival (OS) compared with dexamethasone alone. This current sub-analysis of lenalidomide plus dexamethasone therapy assessed whether there was a survival benefit in maintaining patients on therapy after achieving their best response and what the impact of early discontinuation on TTP and OS was. Methods: Of the 353 patients from MM-009 and MM-010 treated with lenalidomide plus dexamethasone, 32 did not respond. Of the remaining 321 responding patients, 214 had a partial response (PR) or better and 107 patients had stable disease (SD). In this post-hoc sub-analysis, we first assessed the outcome of continuing treatment for ≤10 months vs. >10 months in all 321 patients who achieved SD or better, after they achieved their best response. In this landmark analysis, OS was measured from the time of achieving best response to death from any cause or to last contact. In a second analysis, we assessed the impact of early discontinuation due to adverse events or withdrawn consent on OS and TTP in all patients who achieved SD or better. Therefore, we excluded patients who discontinued treatment due to disease progression, death, or lack of efficacy. Patients who achieved SD or better and who continued on therapy were compared with those who discontinued. OS and TTP were assessed from time of randomization. Results: In the landmark analysis, of the 321 responding patients (≥PR, n=214; SD, n=107), 223 patients received treatment for ≤10 months after achieving their best response and 98 patients for >10 months after achieving their best response. Patients who continued therapy for >10 months after achieving their first best response had significantly longer OS vs. those who received therapy for ≤10 months (not reached vs. 23.4 months; p<0.0001). At 24 months after achieving their best response, significantly more patients were alive if they continued therapy >10 months vs. ≤10 months (93.8% vs. 48.4%, p<0.0001). In the second analysis, in order to evaluate the impact of discontinuation in patients achieving SD or better, we excluded 134 patients due to disease progression, death, or lack of efficacy. Of the remaining 187 responding patients, 72 discontinued treatment for AE (n=42) or withdrew consent (n=30), while the remaining 115 patients continued treatment. Median OS and TTP were significantly longer for patients who continued vs. those who discontinued treatment (median OS: not reached vs. 29.5 months, p<0.0001; median TTP: not reached vs. 13.6 months, p<0.0001). Conclusions: In patients achieving SD or better, prolonged duration of treatment was associated with significantly longer OS and TTP. In contrast, early discontinuation of treatment led to reduced OS and TTP. Therefore, efforts should be made to manage adverse events while maintaining patients on therapy. Furthermore, maintaining treatment with lenalidomide and dexamethasone after achieving the optimal response ensures a significant improvement in OS for patients with relapsed or refractory MM.

Abstract Abstract 2887 Introduction: Cardiac involvement is the major cause of death in patients with immunoglobulin light chain amyloidosis (AL). Detection of cardiac involvement and risk stratification has been facilitated by cardiac biomarkers like troponin T (cTnT) and N-terminal brain natriuretic peptide (NT-proBNP). A novel high sensitivity cTnT (hs-cTnT) assay has been developed, and we evaluated its diagnostic use with three questions in mind: 1) How do the cTnT and hs-cTnT perform in the AL amyloid staging system? 2) Does higher sensitivity add significant additional value in terms of prognosticating outcomes for patients with AL amyloidosis? 3) Can the current AL amyloidosis staging system be further improved upon? Methods: Stored serum samples (-20°C) from 224 pts with AL were analyzed for concentrations of hsTnT, TnT, and NT-proBNP on the E170 Modular analyzer (Roche Diagnostics, Penzberg, Germany). 99th percentile reference limits were <0.014 and <0.010 mcg/L for hsTnT and TnT, respectively. Results: Median values for hsTnT, TnT, and NT-proBNP were 38 ng/L (range 0–075.4), 0.017 mcg/L (<0.0–0.904), and 1230 ng/L (0–32, 226), respectively. The correlation coefficient between hsTnT and TnT was 0.972. Those classified by echocardiographic parameters as having (n=143) or not having (n=81) cardiac involvement had TnT concentrations of 0.04 and 0.01 mcg/L and hsTnT levels of 52.2 and 15.6 ng/L, respectively. The direct numeric result from the hs-cTnT result CANNOT merely be substituted for a cTnT result in the Mayo AL staging system since 14% of patients would be misclassified. The performance of the receiver operation curve derived hs-cTnT cut-point of 54 ng/L is a slight improvement over the direct substitution of 35 ng/L if replacement of one assay for another is required. An alternate staging option using hs-cTnT alone—using the two thresholds14 ng/L and 54 ng/L (figure)—performs as well as either the original Mayo AL staging system or a derivative system incorporating hs-cTnT with respective relative risks of death (95%CI) of 3.6 (2.3, 5.7), 3.8 (2.5, 5.9), and 3.3 (2.2, .50). On multivariate analysis, our newly described alternate 3 level, hs-cTnT alone staging system is independent of other factors including period of diagnosis, type of therapy, and NT-proBNP value, the last of which dropped out of the model. Alternate models using NT-proBNP and cTnT were explored, but none performed better than the original staging system or the new hs-cTnT system. Conclusion: The direct numeric result from the hs-cTnT result cannot merely be substituted for a cTnT result in the Mayo amyloid staging system. Consideration could be made for AL staging systems using hs-cTnT alone and relegating the NT-proBNP for measuring cardiac response. Disclosures: Jaffe: Roche: Consultancy.

Abstract Background While patients with monoclonal gammopathy of undetermined significance (MGUS) are known to be at an increased risk of developing multiple myeloma, Waldenström macroglobulinemia, and primary amyloidosis, the risk of developing non-hematologic malignancies is less clear. A recent report suggested that MGUS patients have a 1.56-fold increased risk of developing nonhematologic malignancies. An excess risk of developing nonmelanoma skin (RR = 2.04), endocrine (RR = 3.34), breast (RR = 1.32), kidney and urinary tract (1.58), respiratory (RR = 1.42), male reproductive system (RR = 1.32), and GI cancers (RR = 1.25) has been reported for people with MGUS (Blood Oct 13 2011;118(15):4086-4092). This study constructed a cohort by discovering MGUS status through medical workup. Therefore, associations discovered might be related to the reason the test was performed more than the result of the test. This study aimed to determine if there was an increased risk of solid malignancies in persons with MGUS using a large, population-based, systematically screened cohort. Methods The population-based cohort established to estimate the prevalence of MGUS was examined for this study (N Engl J Med 2006; 354:1362-1369). Of the 28,038 residents of Olmsted County, Minnesota age 50 years or older as of January 1, 1995, 21,463 individuals' serum samples were collected. All samples were evaluated with serum electrophoresis and immunofixation to determine MGUS status. The Mayo Clinic Medical Index from 1/1/1975 to last follow up or 5/31/2006 was used to link MGUS status to other diagnoses. All patients diagnosed with a solid malignancy were identified, and disease prevalence was determined for cases and controls. For MGUS patients who progressed to MM or related disorder, only solid malignancy diagnoses made prior to progression was considered. A second analysis was performed in which only malignancies that developed after the MGUS screening or diagnosis date were considered. Results 17,315 patients with 435,021 person-years of follow-up were included in the study. Any patient who was blinded in the initial cohort could not be included. Patients with MGUS (n=605) had a mean follow up of 24.64 years (range 0.11 to 30.57) while controls (n=16,710) had a mean of 25.14 years (range 0.01 to 31.40) of follow up. The risk ratio for developing any solid tumor was 1.08 (95% CI 0.94 to 1.25). Persons with MGUS had a 1.61-fold increased risk of developing respiratory tumors over controls. MGUS patients did not have a significantly increased risk of developing cancer in any other anatomical position studied, including bone, brain, breast, endocrine, eye, gastrointestinal, kidney, skin (melanoma or non-melanoma), oral/nasal/pharyngeal, reproductive, or salivary gland. MGUS patients were not found to be at increased risk of developing tumors with a specific pathology over controls. The second analysis, which considered only tumors that developed after the MGUS screening or diagnosis date, showed that MGUS patients were not at an increased risk of respiratory tumors (RR 1.28, p=0.21). According to this analysis, MGUS patients are at decreased risk of developing non-melanoma skin cancer (RR 0.76, p=0.003). No statistically significant increased risk of any solid tumor was identified through this analysis. Conclusion This study used a systematically screened population-based cohort to determine if patients with MGUS are at an increased risk of developing solid tumors. The analysis suggests that patients with MGUS have a significantly increased risk of developing respiratory malignancies (RR 1.61, p=0.01). However, when only tumors diagnosed after MGUS screening or diagnosis date were considered, this risk was no longer significant (RR 1.28, p=0.21). Contrary to previous reports, we did not find patients with MGUS to be at an increased risk of developing other solid malignancies. The discrepancy between these findings and previously reported increased risk may be related to the elimination of ascertainment bias in this population-based cohort universally screened for the presence or absence of MGUS. Accurately understanding the risks associated with MGUS, a condition affecting 3% percent of the population over 50 years of age, may allow for more informed recommendations for screening and counseling for these patients. Disclosures: Kumar: Celgene: Consultancy, Research Funding; Millennium: Consultancy, Research Funding; Onyx: Consultancy, Research Funding.

Abstract The treatment and natural history of smoldering myeloma has been an area of intense preclinical and clinical study. Historical attempts to treat these patients have not demonstrated benefit, likely as a consequence of lack of attention to the vast heterogeneity contained within the diagnosis. More recent risk criteria from both US and Spanish investigators have identified a cohort of smoldering myeloma patients at high risk for progression in a short time, using different methodology. Recently the PETHEMA group published a randomized clinical trial testing lenalidomide/dexamethasone vs observation among high risk smoldering patients, and demonstrated a clear benefit in terms of progression free and overall survival favoring early intervention. However, the risk criteria utilized a highly sensitive method of flow cytometry, a test not routinely available in the US. It is not clear that the group of patients defined in the PETHEMA study share similar outcomes with those defined as high risk using the ECOG/Mayo criteria. A recent publication demonstrated only 25% overlap for the highest risk smoldering patients when using either the PETHEMA or the ECOG criteria. To further evaluate the potential benefit of early intervention in a high risk smoldering cohort, the ECOG myeloma group designed a phase II/III trial testing the safety and efficacy of single agent lenalidomide. We report here on the safety and efficacy of the phase II portion of the trial. The phase II group of patients received lenalidomide alone at a dose of 25 mg days 1-21 every 28 days. The primary endpoint for the safety study was the rate of any treatment-related grade 4-5 non-hematologic toxicity plus grade 3 non-hematologic toxicity that affects vital organ function (such as cardiac, hepatic, or thromboembolic events) observed within 6 cycles of treatment. Patients were to be diagnosed with high-risk smoldering multiple myeloma (SMM) within the past 12 months, as confirmed by both of the following: bone marrow plasmacytosis with >= 10% plasma cells or sheets of plasma cells and an abnormal serum free light chain ratio (<0.125 or >8.0) by serum FLC assay. Patients must have had measurable levels of monoclonal protein. Patients must have had no lytic lesions on skeletal surveys and no hypercalcemia (i.e. >= 11 mg/dL). Among the final phase II cohort (n=44 patients), 55% were female, and 43% were 65 years and older. Enrollment began in January 2011 and lasted 2 years with the last patient completing 6 cycles of treatment in August 2013. The median treatment duration of the entire cohort is 13.5 cycles (range 1-30 cycles). Mean percentage lenalidomide dose over the first 6 cycles was 94, 89, 82, 79, 76, 72. With a median follow up of 17 months, 2 patients had progression on therapy. Fifteen patients are off treatment for the following reasons: disease progression (n=2), AE/complication (n=5), death (n=2), patient withdrawal/refusal (n=5), other (n=1); 6 of the 15 patients ended treatment before completing 6 cycles. Of 44 patients assessed for toxicity, 11 patients [25.0%, 95% CI: (13.2%-40.3%)] experienced worst grade treatment-related non-hematologic toxicity of grade 3 or higher based on CTCAE v4, with neutropenia and fatigue being the most frequent. This includes 2 fatal deaths (MI and TE). Two patients [4.6%, 95% CI: (0.1%-15.5%)] experienced a serious adverse event as defined for the purposes of the phase II toxicity analysis that included treatment-related grade 4-5 non-hematologic toxicity or any grade 3 toxicity affecting vital organ function (such as cardiac, hepatic, or thromboembolic events) during the first 6 cycles of treatment. Twelve patients achieved partial response or better [33.3%, 95% CI: (15.0%-42.8%)] along with 25 patients reporting stable disease. Lenalidomide has shown promise in the treatment of high-risk smoldering myeloma and based on this analysis, accrual to the phase III portion is ongoing. In the context of the encouraging data from the PETHEMA group, completion of the phase III portion of this study is needed to validate their findings using a different criteria, and using a steroid sparing approach. This study was coordinated by the Eastern Cooperative Oncology Group (Robert L. Comis, M.D., Chair) and supported in part by Public Health Service Grants CA23318, CA66636, CA21115, CA13650, CA32102 and from the National Cancer Institute, National Institutes of Health and the Department of Health and Human Services. Disclosures: Lonial: Millennium: Consultancy; Celgene: Consultancy; Novartis: Consultancy; BMS: Consultancy; Sanofi: Consultancy; Onyx: Consultancy.

Abstract 5079 Introduction: IgD monoclonal proteins are rare. They are not seen as a MGUS and are present in 1% to 2% of patients with myeloma. In light chain amyloidosis (AL), IgD monoclonal proteins are rare. When an IgD protein is found, amyloidosis is often omitted from the differential diagnosis. An IgD protein in amyloidosis has been reported in single cases but never as a patient series. We report IgD AL in 53. Patients & Methods: Clinical and demographic data for patients were retrieved from the patient records. Factors of interest were compared between patients who did and did not have an IgD protein. Results: Among 3,955 patients with AL amyloidosis seen, 53 patients (1.3%) had a serum IgD monoclonal protein. (Table 1) A serum monoclonal protein peak was visible on SPE in only 14, and only 5 had an M spike greater than 1 g/dL. On immunofixation of the serum, the IgD light chain was k in 11, λ in 35, and uncertain in 6; 1 patient had a biclonal D λ and G k protein. A urine monoclonal protein was detected in 43 of 51 patients; urinary immunofixation detected a λ light chain in 33 and a k light chain in 10. Biopsy of tissues showed amyloid deposits in the bone marrow in 47% and in the fat aspirate in 73%. Six patients (age 47–63 years) underwent autologous SCT. Four had renal & two had cardiac AL. All 6 had hematologic PR, 4 CR, and 4 had organ response. One patient had relapse of disease and is now on dialysis, and another had relapse and is alive with salvage chemotherapy. One patient had disease relapse and died of progressive GI amyloidosis at 22 months. The other 5 are alive at a median of 68 months (range, 7.5–83.5 months). We compared the 53 patients with IgD amyloidosis with 144 patients with non-IgD amyloidosis. (Table 2) Findings that were significantly different between groups included a lower frequency of renal amyloidosis (P=.005) and a lower prevalence of cardiac amyloidosis (P=.047). There was a higher serum albumin level (P=.04) related to the lower level of proteinuria. No difference in survival was seen between the groups. (Figure). Variables that might affect survival—liver size, performance status, septal thickness, serum creatinine level, and β2-microglobulin level—were not different between groups. Conclusions: IgD AL patients have a lower frequency of renal involvement and possibly also of cardiac involvement. The overall survival of these patients does not appear to be different from that of patients who have AL associated with another monoclonal protein. IgD monoclonal proteins are so closely linked to the diagnosis of multiple myeloma in the mind of a clinician that the possibility of amyloidosis may be overlooked. Disclosures: No relevant conflicts of interest to declare.

Abstract Background Multiple myeloma (MM) is the second most common hematologic malignancy in the U.S. and is characterized by increased immunoglobulin production and infiltration of the bone marrow by malignant plasma cells. Myeloma cell growth is supported by both the elements present in the bone marrow microenvironment as well as deregulation of internal cellular systems associated with proliferation and apoptosis. Defective programmed cell death by BCL2 or MCL1 upregulation is observed in >80% of myeloma cases and is associated with an aggressive clinical course. Remarkably, there is no approved drug with the ability to target BCL2 or MCL1. Various strategies to mitigate the effects of increased BCL2 functionality, via small molecule inhibitors or BCL2-specific antisense oligonucleotides have been previously examined in MM. These studies revealed that 1) apart from BCL2, additional anti-apoptotic members belonging to the BCL2 family (i.e. MCL1, BCL-xL) play integral roles in maintenance of the myeloma cell phenotype, 2) drugs, which target only BCL2 offer limited therapeutic advantage and 3) given that survival factors engaged in MM are multifactorial, perhaps isolated targeting of the BCL2 pathways may not be sufficient. We therefore hypothesized that the clinical development of drugs that target various antiapoptotic BCL2 family members will require a partnership with established anti-MM regimens whose activity can potentially be further enhanced with correction of the apoptotic response system. Aim Since lenalidomide and dexamethasone (LD) is an established therapy for plasma cell cancers, we investigated if the pan-BCL2 inhibitor AT-101 (BH3 mimetic), which has high binding specificity for BCL2, MCL1 and BCL-xL, can be an effective therapeutic partner to enhance anti-MM effects of LD. Methods Human MM (KMS11, U266, OPM2) and WM (BCWM.1) cell lines along with their corresponding bortezomib resistant (BR) clones, (KMS11/BR, U266/BR, OPM2/BR and BCWM.1/BR) which were developed in our laboratory were used in this study. For gene expression profiling, the Illumina HumanHT-12 v3 whole-genome gene expression array and Nanostring nCounter mRNA quantification assays (NanoString, Seattle, WA) were utilized. Statistical analysis was conducted using R-based packages and the MeV software (TIGR). Apoptosis was measured by annexin-v/PI staining, and mitochondrial membrane permeability (MOMP) was assessed using TMRM followed by flow cytometry. Protein profiles were ascertained by western blot. Results Gene expression and immunoblot analysis of six plasma cell cancer models showed upregulation of various BCL2 family members, notably MCL1 and BCL-xL. In a dose-dependent manner, AT-101 was able to downregulate BCL2 and MCL1 and induced apoptotic cell death in MM and WM cells in a dose dependent manner. Tumor cell death was associated with caspase and PARP-1 cleavage accompanied by an increase in MOMP. This cytotoxic effect and BCL2 downregulation were further potentiated when AT-101 was combined with lenalidomide/dexamethasone (LDA). Nanostring nCounter mRNA quantification and IPA analysis revealed differential changes in the CCNA, FRZB, FYN, IRF1, PTPN11 genes in LDA treated cells. IPA canonical pathway analysis demonstrated the p53 signaling and the cyclins and cell cycle regulation pathways to be the most significantly activated by LDA therapy. Summary In summary, we describe for the first time the cellular and molecular events associated with the use of AT-101 in combination with lenalidomide/dexamethasone in preclinical models of plasma cell malignancy. This study lays the rationale for engaging and handicapping the intrinsic apoptotic system through the pan-BCL2 targeting capabilities of AT-101; thus enhancing the anti-MM effects of lenalidomide/dexamethasone. Disclosures: Foran: Celgene: Research Funding.

Abstract Abstract 2868 Introduction: Improvement in renal parameters is fundamental for the assessment of organ response to treatment in immunoglobulin light chain amyloidosis (AL). Renal response, defined as a >50% reduction in proteinuria with <25% decrease in renal function, is associated with superior overall survival (OS); however, a systematic study of the interplay of proteinuria, creatinine, and free light chain has not been performed. The intent of this study is to better understand the components of the renal response criteria. Methods: Patients who underwent autologous stem cell transplantation from 1995 to 2010 were eligible for this retrospective analysis if they had > 1 year of follow-up and a baseline 24 hour urine protein > 1 g/d. Those who were dialysis dependent or died before 1 year were excluded as not evaluable for renal response. Results: Of the 435 patients screened, 152 met criteria. On univariate analysis, >50% proteinuria reduction (p < 0.001), serum free light chain (sFLC) reduction by >50% (p = 0.002), <25% increase in serum creatinine (Scr) (p = 0.0003), and a 50% proteinuria reduction within 15 months of treatment (p = 0.04) were associated with better OS. Multivariate analysis using a proportional hazard model showed that sFLC reduction by >50% (0.006), <25% increase in serum creatinine (Scr) (p = 0.0005) and >50% proteinuria reduction (p = 0.0006) were independently associated with OS. In addition, OS was significantly better among patients achieving >85% reduction in proteinuria than those with < 85% but >50%, p = 0.03 (Figure 1). Patients with >75% reduction in sFLC were more likely to achieve >50% proteinuria reduction (p = 0.009). Most importantly, among those with > 25% increase in Scr, only those patients who had <85% proteinuria reduction had a worse OS (Figure 2a, p = 0.006). There was no difference in OS among those with >85% proteinuria reduction and a rise in Scr of > 25% (Figure 2b, p = 0.77). Conclusion: Renal response is an excellent prognostic marker in patients with AL. This is the first study to show the depth of renal response correlates with OS. Patients who had the highest levels of proteinuria reduction (> 85%) had a significantly better OS than those with >50% but <85%. We also found that the negative impact of >25% decrease in renal function was only pertinent in those who did not have >85% reduction in proteinuria. These findings should help better refine the definition of renal response criteria in AL patients. Disclosures: Leung: Binding Site: Honoraria.

Abstract Abstract 2945 Background: We have previously reported on a Phase II trial using IL-1Ra and dexamethasone, in patients with SMM/IMM, showing that IL-1Ra targets the myeloma proliferative component which parallels a decrease in the C-reactive protein, a surrogate for IL-6 production. (Mayo Clinic Proceedings 84 :114 (Feb. 2009)). In early stage myeloma, IL-6 is a central myeloma growth factor and we have shown that abnormal production of IL-1 β in the myeloma microenvironment stimulates the generation of paracrine IL-6. These patients are the individuals most likely to benefit from anti-cytokine therapy in an attempt to delay/prevent the development of active myeloma. We now present updated results of this study including survival data. Methods: Patients that had ≥ 10% bone marrow plasma cells and/or an IgG or IgA M-spike ≥ 3 g/dL and did not require immediate chemotherapy were eligible. All patients received 100 mg of Anakinra (IL-1Ra) SQ qd for 6 months. Patients with evidence of reduction in M-protein levels continued receiving IL-1Ra alone. Patients with stable disease at 6 months or those with a rising M-protein before 6 months received low dose dexamethasone (20 mg qweek) in addition; the dose was adjusted based on response/toxicity. Results: Data were available on 47 patients based on intent to treat, and pts were classified as smoldering (72%) vs. indolent (28%). All SMM patients were in Group 1 or 2 and thirty-eight patients (81%) had greater than 20% bone marrow plasma cells. All 47 patients received IL-1Ra initially and 25/47 subsequently received IL-1Ra/Dex. Seven patients had a decrease in the plasma cell labeling index (PCLI) on IL-1Ra alone which paralleled a decrease in the high sensitivity C-reactive protein (CRP) in all cases. Three patients achieved a minor response to IL-1Ra alone and 9 patients achieved a PR/MR after addition of dexamethasone. For the group of 47 patients, the median progression-free survival was 45 months and the median overall survival has not been reached. When patients were grouped into whether they exhibited a reduction in the C-reactive protein from baseline after 6 months of therapy, the median PFS for patients without (21 patients) or with (26 patients) a greater than one-third reduction in baseline CRP was 1 year vs more than 8 years (p<.01). Similarly, the median OS for patients without or with a reduction in baseline CRP was 7.9 years vs. median not reached (p=.02; see Figure). Toxicity included injection site reactions during the first month of therapy in 86% of patients. Grade 3–4 adverse events consisted mainly of asymptomatic neutropenia (17% of patients) and infection (18% of patients). Patients that progressed to active MM have been treated with standard therapies including lenalidomide, bortezomib, transplant, and novel therapies. In contrast, seven of the 26 patients with a CRP decrease continue with stable disease and minimal toxicity on IL-1Ra alone or in combination with standard agents. Conclusion: The above results suggest that agents such as IL-1Ra that specifically inhibit paracrine IL-6 production are effective at targeting the proliferative myeloma component and warrant further investigation in combination with standard myeloma therapies. Combination therapy that effectively targets both the proliferative and the IL-1 producing myeloma components may be useful in patients with active myeloma that have an elevated growth rate at diagnosis. Disclosures: Lust: Mayo Clinic: Patents & Royalties. Off Label Use: IL-1Ra use in smoldering myeloma. Donovan:Mayo Clinic: Patents & Royalties.

Abstract Abstract 2950 Background: The median age of patients diagnosed with MM is approximately 70 years, and it is a relatively uncommon disease in the younger population. Both conventional chemotherapy and stem cell transplantation (SCT) have favorably impacted the overall survival (OS) of young MM patients. The median survival of patients < 40 years of age, diagnosed prior to 1993 was reportedly 54 months at our institution. However, the impact of novel agents in this patient population is not well known. We studied the outcome of young patients presenting to our institution over the last decade. Methods: Records of 1538 patients presenting between 01/99 to12/08 were reviewed. The demographics, features and therapeutic interventions in patients up to 45 years of age at diagnosis were analyzed using descriptive statistics. The survival outcome of this group was compared with the remainder of the cohort using the Kaplan-Meier method. Results: One-hundred (6.5%) out of 1538 newly diagnosed MM patients were ≤ 45 years of age at diagnosis. The median follow-up of this group of young patients was 86 months. The disease and patient characteristics are outlined in table 1. A median of 5 regimens (range 1–14) was administered, and 85% patients had received high-dose therapy. 15 patients underwent allogeneic SCT after at least one prior autologous SCT. Novel agents were used both in the front-line and relapsed setting (lenalidomide 60%, thalidomide 56%, pomalidomide 9% and bortezomib 49%), and 45% of initial regimens were novel agent based. The 5 and 7-year OS from diagnosis was 69% and 59%, respectively and the median OS was 93 months. In contrast, the median OS of patients >45 years diagnosed during this period was 53 months (P=0.001, figure 1). Conclusion: A marked improvement in OS of young patients with MM diagnosed in the novel agent era is noted in comparison to the historical control of similar age group. In addition, the age associated survival benefit in the younger patient population prevails in the era of novel therapies. Disclosures: Gertz: Celgene: Honoraria. Lacy:Celgene: Research Funding. Dispenzieri:Binding site: Honoraria; Celgene: Research Funding. Kyle:Millennium: Consultancy; Binding Site: Honoraria. Kumar:Millennium Pharmaceuticals, Inc.: Research Funding; Celgene: Consultancy, Research Funding; Genzyme: Research Funding; Novartis: Research Funding; Merck: Consultancy, Honoraria.

Abstract Background Pomalidomide (POM) is the newest Immunomodulatory agent (IMiDs) that has shown clinical efficacy in relapsed multiple myeloma (MM) refractory to lenalidomide (LEN) and thalidomide (THAL). Studies of MM cell microenvironment suggest that tumor subclones compete for dominance during changes in drug therapy. It was previously observed that a minor clonal population increased in prominence of MM cells after 1 year of treatment with LEN. We examined whether the patients having THAL or LEN as the most recent prior-line therapy affects response to POM. Methods We studied 208 patients enrolled in a phase II trial of POM / dexamethasone between November 2007 and March 2012 at Mayo Clinic, Rochester. We reviewed the immediate prior-line therapy before enrollment in our trial. Comparison of treatment duration of POM and response rates were conducted between patients who had either THAL or LEN as latest prior-line therapy, and patients who were treated with non-IMiDs immediate before enrollment in POM trial. Treatment duration of POM was estimated using Kaplan Meier method and the survival curves were compared using log-rank test. We used univariate Cox proportional hazard models to estimate the prognostic impact of different variables. Results The median age of patients was 63 (range from 32 to 88). 68 % were males. 80 patients (38.5%) had THAL or LEN immediate prior to POM. Median prior-line therapies were 3. Patients who received THAL or LEN immediately prior to POM had a lower response rate than those who had non-IMiDs as latest therapy (29% vs 44%, p 0.04) and shorter median duration of POM treatment (5.7 months vs 7.3 months, p 0.02). In 190 (91%) patients who were previously treated with LEN and THAL at any time, median time between the end of LEN or THAL treatment and the initiation of POM was higher for POM responders than non-responders (10 months vs 3 months, p 0.0008). Patients responded to POM had a shorter duration of prior LEN or THAL treatment compared to non-responders (9 months vs 15 months, p 0.001). Conclusion THAL or LEN as an immediate prior-line therapy to POM is associated with a lower response rate and shorter effective treatment duration. Longer interval between prior immunomodulatory compounds and POM, and shorter exposure to previous immunomodulatory compounds are associated with better POM treatment response. Disclosures: Gertz: Celgene: Honoraria. Kumar:Merck: Consultancy, Honoraria; Celgene: Consultancy, Research Funding; Millennium: The Takeda Oncology Company: Research Funding; Novartis: Research Funding; Genzyme: Research Funding. Lacy:Celgene Corporation: Research Funding.