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Abstract Aim: A phase III trial of lenalidomide plus high (standard) dose dex (RD) versus lenalidomide plus low dose dex (Rd) in newly diagnosed myeloma (MM). Methods: Pts with untreated, symptomatic MM were eligible. Pts in the RD arm (Arm A) received lenalidomide 25 mg/day PO days 1–21 every 28 days plus dex 40 mg days 1–4, 9–12, and 17–20 PO every 28 days; pts in the Rd arm (Arm B) received lenalidomide at the same dose plus dex 40 mg days 1, 8, 15, and 22 PO every 28 days. The primary endpoint was response rate at 4 months, with the null hypothesis being that the response rates in the two 2 arms are equivalent. Planned sample size was 196 eligible pts per arm with one-sided 0.10 Type I and 0.05 Type II error rate. All analysis were performed on an intent to treat basis. An independent DMC recommended release of study results. Results: 445 pts (median age, 65 yrs) were accrued; 223 randomized to RD, 222 to Rd. Median follow-up time is 17 months. Arms were well balanced for age, gender, stage, bone lesions, hemoglobin, beta-2 microglobulin, performance status, bone marrow plasma cells, and M protein levels at baseline. Major grade 3 or higher toxicities, including DVT/PE and infections, were significantly higher in the high dose dex arm (see Table). Overall survival (OS) at the second pre-planned interim analysis was significantly superior with lenalidomide plus low dose dex, P<0.001; one year survival 96% (Rd) versus 87% (RD). The 18 month survival rate is 91% versus 80%, respectively. OS differences in favor of the low dose dex arm were seen in pts <65 (P=0.022; one year rate 97% vs 92%) as well as pts 65 and older (P=0.002; one year rate 94% vs 83%), respectively. Sixty-one patients have died; 42 in the RD arm and 16 in Rd arm. The cause of death has been verified by detailed chart review in 38 patients. Of 29 verified deaths in the RD arm, 13 were due to disease progression, 6 thrombosis/embolism, 3 infection, 3 cardiac ischemia, 1 stroke, and 1 respiratory failure. Of 9 verified deaths in the Rd arm, 5 were due to disease progression, 2 infection, 1 thrombosis/embolism, and 1 cardiac arrest. Response rate data are expected to be available at the time of the meeting. Conclusions: Lenalidomide plus low-dose dexamethasone (Rd) is associated with superior OS compared to lenalidomide plus high-dose dexamethasone (RD) in newly diagnosed MM. The increased mortality in Arm A is due to disease progression (myeloma deaths) as well as increased toxicity. This study has major implications for the use of high-dose dexamethasone in the treatment of newly diagnosed MM. Major Grade 3 or Higher Adverse Events Toxicity Arm A % Arm B % P value Neutropenia 10 19 0.01 DVT/PE 25 9 <0.001 Infections 16 6 <0.001 Any grade 3 or higher non-hematologic 49 32 <0.001 Any grade 4 or higher non-hematologic 20 9 <0.001 Deaths in first 4 months 5 0.5 0.006

Abstract Background: Myelodysplastic syndromes (MDS) are rare hematological neoplasms that are more typically seen in elderly patients. Young patients (< 50 years old) have been reported to comprise between 3-6% in the Surveillance, Epidemiology and End Results (SEER) (Ma X et al, Cancer 2007; Rollison R et al, Blood 2008) with a better overall survival (OS). We hereby report the characteristics of young MDS patients with long survival follow-up. Methods: A total of 1012 MDS patients' data from Oct 1993 to Dec 2015 at Mayo Clinic were reviewed after appropriate IRB approval was obtained. All cases had their bone marrow slides reviewed at our institution. Patients youngers than 50 years old (yMDS) were included as cohort 1, while the rest was included as control group (cohort 2). Prognostic factors were analyzed by univariate and multivariate analyses. Survival estimates were calculated using Kaplan-Meier curves and univariate and multivariate analyses was based on log-rank testing using JMP software version 10. Results: Characteristics: We identified 68 (7%) yMDS patients with a median age of 42 years (range, 18-49). Female gender was more common in yMDS (43% vs 31%, p= 0.05). Upon comparison between cohort 1 and 2, only platelets were significantly lower in yMDS (61 vs 102, p <0.0001), but not white blood cells, hemoglobin or degree of marrow fibrosis. MDS subtyping according to World Health Organization 2016 showed single lineage dysplasia in 15% vs 2%, multilineage dysplasia 24% vs 36% , ring sideroblasts 9% vs 15%, isolated del (5q) 1% vs 3%, excess blasts 44% vs 31%, and unclassifiable in 6% vs 5%. As expected, therapy related MDS (t-MDS) was more frequent in yMDS (33% vs 17%, p= 0.005). Transformation to acute myeloid leukemia (AML) was also more frequent in yMDS (28 % vs 11%, p= 0.0004). Compared to cohort 2, yMDS IPSS-R scores were very high, high, intermediate, low, and very low in 24% vs 13%, 29% vs 16%, 21% vs 20%, 19% vs 35%, and 7% vs 17%, respectively. Allogenic hematopoietic cell transplantation (HCT) was more frequent in yMDS (42% vs 4%, p< 0.0001). Survival outcome: Median OS was longer for cohort 1 vs cohort 2 but did not reach statistical significance (43 vs 21 months, p= 0.1). Median progression free survival (PFS) was shorter for cohort 1 vs cohort 2 but did not reach statistical significance (8 vs 12 months, p= 0.3). Median OS for cohort 1 based on R-IPSS was 44, 105, 40, 18, and 12 months for very low, low, intermediate, high and high risk groups, respectively (p= 0.09). Median OS was shorter in t-MDS vs de novo MDS in cohort 1 (13 vs 47 months, p = 0.04). Young patients who had transformed to AML had a worse median OS (18 vs 93 months, p=0.001). On multivariate analysis neither t-MDS nor R-IPSS had a statistically significant impact on OS. Conclusions: MDS is rarely diagnosed under the age of 50. IPSS-R was less powerful in detecting differences between its risk groups for this patient population, although more than half of the patients with yMDS had either high or very high risk. Among this cohort of yMDS patients, there was a significantly higher proportion with therapy-related myeloid neoplasms compared to older patients (one third of patients), with subsequent higher rates of transformation to AML and higher allogeneic HCT. In our study, we did not find an improved OS for yMDS patients compared to older patients. Disclosures Al-Kali: Celgene: Research Funding; Onconova Therapeutics, Inc.: Research Funding.

Abstract Background: Immunomodulatory agents and proteasome inhibitors have significantly improved outcomes in the management of patients with multiple myeloma (MM). As a consequence, the role of upfront autologous stem cell transplant (ASCT) has become more controversial. The ECOG-ACRIN Cancer Research Group trial E4A03 demonstrated the superiority of lenalidomide (LEN) and low-dose dexamethasone (DEX; Ld) over LEN and high dose DEX (LD) in newly diagnosed MM (Rajkumar SV, Lancet Oncol, 2010). This led to the universal acceptance of Ld as a standard induction regimen. More recently, the FIRST study demonstrated the superiority of Ld as continuous therapy vs Ld given x 18 cycles and melphalan-thalidomide-prednisone x 12 cycles proving continuous Ld should be considered standard of care (Benboubker L, NEJM, 2014). Upon completion of four cycles of therapy, patients enrolled in E4A03 had the option of proceeding to ASCT or continuing on their assigned Ld or LD. A prior post-hoc retrospective landmark analysis (Siegel DS, Abstract, Blood 2010) comparing outcomes of early ASCT vs. no early ASCT showed that in patients <65, 65-70, and >70, the survival with early ASCT at 3 years appeared higher, supporting the role of early consolidative ASCT in newly diagnosed patients. This analysis is the long-term follow-up of the aforementioned study. Methods: A post hoc, retrospective landmark analysis was performed evaluating overall survival (OS) by early ASCT vs. no early ASCT overall and within age subgroups. The Kaplan-Meier method was used to estimate survival distributions and Cox regression for hazard ratio (HR) estimates. The landmark analysis included only patients surviving the first four cycles of therapy. Results: 21% of patients opted for early ASCT (n=90). At baseline (four cycles prior), early ASCT patients were younger (median 57.5y vs 66y), more fit (ECOG PS 0 45% vs 56%) and with less aggressive disease (ISS Stage 3 12% vs 28%). Median treatment duration was 7.6m for no early ASCT patients. The 1, 2, 3, 4, and 5-year survival probability estimates were higher for early ASCT vs. no early ASCT at 99%, 93%, 91%, 85%, and 80% vs. 94%, 84%, 75%, 65%, and 57%. The median OS in the early ASCT vs. no early ASCT was not reached vs. 5.8 years, respectively (Table 1). The survival hazard ratio (HR) for early ASCT was 0.55 [95%CI (0.38-0.80)]. In a further subgroup analysis of patients </= 65, 5-yr survival probability of those who had early ASCT vs. no early ASCT was 79% [95%CI (67-87)] vs. 62% [95%CI (54-69)], respectively. In patients </= 65, median OS in the early ASCT vs. no early ASCT was not reached vs. 7.4 years and the survival HR was 0.74 [95%CI (0.48-1.15)]. For patients >65, 5-yr survival probability of those who had early ASCT vs. no early ASCT was 83% [95%CI (56-94)] vs. 52% [95%CI (45-59)], respectively. In patients >65, median OS in the early ASCT vs. no early ASCT was not reached versus 5.2 years and the survival HR was 0.38 [95%CI (0.17-0.87)]. In all age groups, overall response rate was similar prior to the decision of proceeding with ASCT vs. no early ASCT. In a multivariable model adjusting for baseline prognostic factors, early ASCT retained marginal significance. Conclusions: The landmark analysis demonstrated that patients opting for ASCT after induction Ld/LD had a higher 1, 2, 3, 4, and 5- year survival probability and improvement in median OS regardless of DEX dose density. Results were stronger within the older age cohort and upheld in adjusted models. Limitations include lack of randomization and data on salvage therapy. At a time when lenalidomide and dexamethasone as induction is gaining worldwide acceptance in all age groups, early ASCT is safe and efficacious and should remain a standard of care for newly diagnosed MM even in the era of novel therapies. Table 1. Survival Probabilities (Time from Registration) for all Patients Included in the Landmark Analysis Median 1 year 2-year 3-year 4-year 5-year N Events Median (Yrs)(95% CI) Events Survival Probability(95% CI) Events Survival Probability(95% CI) Events Survival Probability(95% CI) Events Survival Probability(95% CI) Events Survival Probability(95% CI) No Early ASCT All 341 195 5.78(5.11 - 6.59) 22 0.94 (0.90 - 0.96) 53 0.84 (0.80-0.88) 84 0.75 (0.70-0.79) 119 0.65 (0.59-0.69) 144 0.57 (0.51 - 0.62) Early ASCT All 90 34 NR 1 0.99 (0.92 - 1.00) 6 0.93 (0.86 - 0.97) 8 0.91 (0.83 - 0.95) 13 0.85 (0.76 - 0.91) 18 0.80 (0.69 - 0.87) NR = not reached Disclosures Biran: Celgene: Speakers Bureau. Siegel:Celgene Corporation: Consultancy, Speakers Bureau; Amgen: Speakers Bureau; Takeda: Speakers Bureau; Novartis: Speakers Bureau; Merck: Speakers Bureau. Fonseca:Millennium: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; Applied Biosciences: Membership on an entity's Board of Directors or advisory committees; Onyx/Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; Binding Site: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; Bayer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding. Vesole:Idera Pharmaceuticals: Research Funding; Celgene Corporation: Speakers Bureau. Williams:Celgene: Consultancy, Research Funding. Abonour:Celgene: Research Funding, Speakers Bureau.

Abstract Background: The serum free light chain (FLC) ratio is a readily available laboratory test that has independent prognostic significance in monoclonal gammopathy of undetermined significance (MGUS) (Blood2005;106:812–17) and solitary plasmacytoma (Blood2006;108:1979–83). The purpose of this study was to determine if the FLC ratio will be of prognostic value in multiple myeloma (MM). Methods: We used a well characterized cohort of 1027 newly diagnosed MM patients seen at Mayo Clinic from January 1, 1985 to December 31, 1998 (Mayo Clin Proc2003;78:21–33) to ensure adequate follow up. Archived serum samples from blood drawn within 30 days of initial diagnosis were available on 790 of the 1027 patients. Quantitation of serum free κ and λ concentrations was performed on the archived sera by immunonephelometry, using specific antibodies on a BNII nephelometer. FLC ratio was calculated as κ /λ, i.e., free κ concentration divided by free λ, reference range 0.26–1.65. If the FLC ratio is >1.65, κ is considered to be the “involved” FLC and λ the “uninvolved” FLC, and vice versa if the ratio is less than 0.26. Incorporation of FLC into the International Staging System (ISS) was assessed in 576 of 790 patients (73%), in whom samples or data were available to estimate the ISS. Results: 790 patients (median age 66 years) were studied. The FLC ratio was outside the reference range in 95.1% of patients. The median involved κ and λ concentrations were 37.1 and 71.3 mg/dL, respectively. A cut-point κ /λ FLC ratio of <0.03 or >32 was chosen for further modeling analysis on the basis of its separation of the cohort into two roughly comparable parts. Overall survival was significantly inferior in patients with an FLC ratio <0.03 or >32 (n=479 patients) compared to those with an FLC ratio that was 0.03–32 (n=311 patients), with median survival of 30 versus 39 months, respectively, P<0.001 (hazard ratio 1.3, 95% CI 1.12–1.54). The FLC ratio (<0.03 or >32) retained independent significance after adjusting for the International Staging System (ISS) (P=0.03). The FLC ratio made the most significant contribution to predicting prognosis in patients with ISS Stage 2 (n=265 pts), separating this category of patients into those with 5 year survival rates of 20.5% (FLC ratio <0.03 or >32; n=152 pts) versus 35.2% (FLC ratio 0.03–32; n=113 pts), P=0.02. We studied the additional prognostic value of the serum FLC to the variables used in the ISS by defining FLC ratio <0.03 or >32, Sβ2M ≥3.5 g/L, and serum albumin <3.5 g/dL as three risk factors in a risk-stratification model. Patients with 0, 1, 2, or 3 risk factors had significantly different overall survival, with median overall survival times of 51, 39, 30 and 22 months, respectively, P<0.001. Conclusions: The serum FLC ratio at initial diagnosis is an important predictor of prognosis in myeloma. We show that the serum FLC ratio can be incorporated into the ISS, providing the greatest prognostic value in ISS Stage 2 patients, as well as providing a new risk-stratification model.

Abstract Genetic variations in patient populations likely contribute to disease progression and therapeutic outcomes. We have begun a systematic approach to examine the association of genetic variations (ie. functional, single nucleotide polymorhisms, SNPs) involved in myeloma growth promotion, metabolic events, drug responses, and DNA repair on clinical outcome in the intergroup trial S9321. This trial tested a single high dose regimen with autologous stem cell support against a conventional dose regimen, with further randomization of responders to maintenance with interferon or not, in newly diagnosed patients with multiple myeloma. ECOG, CALGB and SWOG enrolled 899 patients with newly diagnosed MM to receive VAD induction x 4 cycles followed by randomization to PBSC-supported high dose therapy (HDT) versus standard dose therapy (SDT) of VBMCP, using CTX 4.5 g/m2 + G-CSF for PBSC mobilization in all patients. Responders to VBMCP or HDT were randomized to IFN or no maintenance. Specimens were distributed through ECOG for biologic correlative studies, including candidate SNP analysis. SNP assays have been developed using the Sequenom Mass-extend platform for functional SNPs in IL-6, IL-1, IL-RA, IL-10, TNF, Lta, TGFb, MDR1, MPO, CYP3A4, GST (M, P, T), ERCC2 and XRCC1, and are being evaluated on 803 DNA samples prepared from patients enrolled in S9321. Preliminary findings (n=135) demonstrate functional genetic variants of IL-10 (position -1082), IL-1 (position +3953), TGFb (postion -509), and TNFa (position -308) are showing trends associated with differences in progression free survival; and variants in IL-6 (position -174) are associated with response. Median survival of the IL-10 variants was 31 months for A/A low producer alleles versus 19 months for the G/G high producer alleles (p=.5). For TNFa, 2 cases with the high producer A/A alleles died within a year, while the median survival for the lower producer G/G alleles was 2 years (p=.04). For patients with the high producer C/C/ allele of IL-1 (n=67), median survival was 2 years, versus 5 patients with the T/T low producer alleles that had a median survival greater than 5 years (preliminary p=.29). While these preliminary results are now only suggestive of trends in genetic polymorphisms associated with clinical outcome, completion of the full SNP panel on the entire sample base should provide a extensive association study, and analysis of potential differences in therapy arms of the trial. The full panel and association studies will be presented.ααββααα

Abstract Although multiple myeloma is clinically defined as the accumulation of clonal, malignant plasma cells in the bone marrow, the disease shows significant heterogeneity with regard to morphology, progression and therapeutic response. Our hypothesis is that this heterogeneity likely is due, in part, to germline genetic polymorphisms that contribute significantly to an individual’s disease course and response. In particular, individuals deficient in the repair of DNA damage are not only at high risk for developing cancer, but also could show DNA repair dependent responses associated with DNA damaging therapeutic agents. In this study we examined the association of functional genetic polymorphisms in the DNA repair genes, XRCC1 (SNP positions 280, 399) and ERCC2 (SNP positions 312, 751), with toxicities and clinical outcomes in the ECOG, 3 arm chemotherapeutic trial, E9486 [A-VBMCP, B-VBMCP+Cylophosphamide, C- VBMCP+interferon]. DNA from 359 patients was genotyped and examined for association with response, toxicities, blood counts, bone pathology, and survival parameters. Notably, in the interferon arm of the trial significant associations were observed in progression free survival and polymorphisms of XRCC399 (AA median survival 51 months versus AG/GG median survival of 33 months; p=,008), ERCC751 (AA/AC median survival 33 months versus CC median survival of 48 months; p=.05), and ERCC312 (AA median survival 49 months versus AG/GG median survival of 34 months; p=.02). Hazard ratios ranged form 1.7 to 2.05 for survival differences associated with DNA repair genes in this arm. Interestingly, T cell counts are known to be impacted by interferon; and DNA repair polymorphisms in this arm were also associated with CD8+ T cell counts. While this represents a single arm of one clinical trial, it is intriguing to consider the impact of genetic polymorphisms on DNA repair in light of chemotherapeutic agents that may affect cells of the immune system. Previous studies from the ECOG Myeloma Committee of the E9486 trial show highly significant associations of survival and immune status in myeloma patients. Our results suggest genetic polymorphisms in DNA repair genes may influence clinical outcome in certain therapeutic regimens. Genetic polymorphisms in these DNA repair genes are currently being completed in 800 patients of the SW9321 SWOG/ECOG intergroup trial and additional association studies will be included in the presentation.

AbstractRecent analyses of circulating blood B cells in myeloma have generated controversy concerning the exact levels of these cells and whether they may represent circulating clonal tumor B cells. Previous reports suggested that CD19+ B cells are markedly increased in myeloma patients and that this population shares clonotypic rearrangements with the malignant plasma cell. We studied the numbers of CD19+ B cells by flow cytometry in previously untreated newly diagnosed myeloma patients in Eastern Cooperative Oncology Group (ECOG) phase III trial E9486. There were 628 patients who were eligible for the clinical protocol E9486, but of these 521 were also entered on the companion laboratory study (E9487) and had CD19 data. In comparison with normal controls, the myeloma patients exhibited a marked heterogeneity in the number of circulating CD19+ B cells as detected by flow cytometry. Approximately 20% of patients had significantly increased levels of circulating CD19+ B cells. However, the total CD19+ blood population from myeloma was not significantly different from the median of age-matched, normal controls. Analysis of CD19+ blood cells in relationship to circulating clonal cells was done in 13 myeloma patients using a clonotypic, quantitative allele-specific oligonucleotide-polymerase chain reaction (PCR) assay. No correlation was found between the numbers of CD19+ B cells (range, 5% to 51%) and PCR estimates of the number of clonal cells in the peripheral blood (range, .009% to 3.6%). Low CD19+ B-cell level (&lt;125 μL) was associated with clinical stage III (P = .033). A significant relationship exists between higher levels (≥125/μL) of CD19 cells and longer overall survival (P &lt; .0001). In addition, high CD19 levels also predicted a clinical response and longer event-free survival. There was a strong inverse association between the level of CD19 values at diagnosis and infections within the first 2 months of diagnosis. Importantly, the number of deaths related to infections was significantly greater in the low versus high CD19 group (P &lt; .0202). Also, CD19 is an independent prognostic factor in addition to plasma cell labeling indices, β2 -microglobulin, hemoglobin, and plasmablastic morphology. Patients with infections were more likely to have low levels of CD19+ cells. In summary, higher CD19+ cell levels are a favorable prognostic sign with no apparent relationship to circulating tumor cells. In addition, this analysis strongly suggests that low peripheral blood levels of CD19+ cells are an adverse prognostic sign in myeloma. The CD19+ cell levels in myeloma patients is an important parameter in the overall assessment of these patients.

Abstract Abstract 1802 Poster Board I-828 Background Heterogeneity in multiple myeloma (MM) leads to disparate outcomes with a wide variation in overall survival (OS). Based upon the evidence predominantly gathered from newly diagnosed patients treated with standard chemotherapy and/or transplantation, the current Mayo (mSMART) prognostic model uses a combination of metaphase cytogenetics, fluorescence in-situ hybridization (FISH) and plasma cell labeling index (PCLI) for risk-stratification at diagnosis of MM. The objective of our study was to evaluate the significance of this stratification model in the era of novel therapies, and to assess the independent prognostic value of each of the components in the model. Methods Data were abstracted from a cohort of 1556 consecutive patients with MM who presented to our institution between January 1999 and March 2009 within ninety days of diagnosis of MM A total of three hundred and eighty six patients had been evaluated with conventional cytogenetics near diagnosis in addition to interphase FISH. Out of this cohort, three hundred and sixty six patients had availability of all the three tests, including the slide-based PCLI. High-risk MM was defined as presence of any one or more of the following: cytogenetics: hypodiploidy, monosomy of chromosome 13 or deletion 13q ; FISH: deletion of p53 (locus 17p13) or immunoglobulin heavy chain (IgH) translocations, t(4;14) (p16.3;q32) or t(14;16)(q32;q23); PCLI ≥3%. Survival estimates were created using the Kaplan-Meier method and compared by log-rank tests. The impact of each of the three tests was assessed by a multivariate (MV) analysis using Cox proportional hazards model. Results The median OS of the cohort of 366 patients was 65 months from presentation. One hundred and twelve (31%) patients were deemed high risk by any one or more of the three tests: Metaphase cytogenetics, FISH or PCLI (current mSMART definition of high-risk MM). The median OS of high risk patients was 52 months versus 71 months for standard-risk (P=0.007). We then studied the prognostic value of the three tests separately. Patients classified as high risk by FISH had a median OS of 35 months versus 65 months for the standard risk, HR= 2.3, P<0.001. Similarly, cytogenetics alone was also able to classify patients into high and standard risk with a comparable HR of 2.1 (P=0.008, median survival 37 vs. 64 months). In contrast, PCLI did not have a significant prognostic value (HR =1.41, P=0.32). This was confirmed on multivariate analysis in a model that included all 3 tests. FISH (HR=2.36, P=0.001) and cytogenetics (HR=1.99; P=0.017) emerged as independent determinants of prognosis in the multivariable analysis, while PCLI (HR=1.03, P=0.93) did not provide additional prognostic value. We then examined whether the prognostic value of FISH contributed additionally in patients classified into high and standard risk by conventional cytogenetics, and vice versa. Those classified as high risk by cytogenetics (n=44, 11 %), were further categorized into 2 groups by additional prognostic information obtained by FISH (median survival 18 vs. 52 months; P=0.005). Similarly, those classified as standard risk by cytogenetics (n=342, 89 %), were further categorized into 2 groups (median survival 52 vs. 71 months; P=0.017) by additional FISH-based stratification. Similarly, high-risk patients defined by FISH (n=65, 17 %) were further classified into 2 groups with significant difference in median OS (18 vs. 52 months, P=0.004), based on the presence or absence of high-risk features on cytogenetics. In contrast, no additional prognostic information was gained by cytogenetics in patients who were stratified as standard risk by FISH alone (n=321, 83%). Conclusion Our study validates high risk features defined by FISH and conventional cytogenetics in the mSMART risk stratification model among patients treated after the introduction of novel therapies. Either test identifies a high risk cohort with a hazard ratio of approximately 2 (median survival ∼37 versus ∼65 months). In patients known to have high risk disease by one of the two tests, knowledge of the other appears to add additional prognostic value. Disclosures Fonseca: Amgen, BMS, Celgene, Otsuka, Genzyme and Medtronic: Consultancy. Gertz:celgene, millennium: Honoraria. Dispenzieri:celgene: Research Funding. Kumar:celgene, genzyme, millennium, novartis, bayer: Research Funding; genzyme: Membership on an entity's Board of Directors or advisory committees.

Abstract Abstract 1988 Background With the utilization of novel agent-based combination therapies and autologous stem-cell transplantation (ASCT) in multiple myeloma (MM), the rigorous response category of stringent complete remission (sCR) in the international uniform response criteria is increasingly becoming attainable. In addition to the standard criteria for complete remission (CR), sCR requires normalization of the free light chain ratio and disappearance of clonal cells as determined by the marrow immunofluorescence or immunohistochemistry. We have previously validated the new response category of sCR created in by the International Myeloma Working Group and demonstrated that sCR represents a deeper level of response, translating into a superior OS. Herein we report the survival outcomes of patients attaining sCR or standard CR, from a 2-year landmark after ASCT in a cohort of patients with extended follow-up. Additionally, we report the outcome of patients who remained in sCR for at least 6 months (sustained-sCR) after ASCT. Patients and Methods Maximal response rates of four hundred and forty-five consecutive patients who underwent ASCT within 12 months of diagnosis of MM were determined. The population achieving varying degrees of complete remission (n=237) is the focus of this study. We performed a landmark analysis 2 years after ASCT to ensure that all the patients attaining at least CR had sufficient time to reach the response levels being studied. Patients were categorized as having sustained sCR (sus-sCR) if the duration of sCR was at least 6 months. Overall survival (OS) was estimated by the Kaplan Meier method and the survival curves were compared by log-rank test. Results The median follow-up of the entire cohort was seventy-seven months (95% CI: 73–82 months). The sCR rate after ASCT was 24% (n=109). Median time to progression (TTP) of patients attaining sCR was 50 months from ASCT, and median overall survival (OS) is not reached, in contrast to those attaining standard CR (n=37, TTP=20 months, OS=81 months) or near CR/nCR (n=91; TTP= 19 months, OS=60 months, p<0.0001 for both TTP and OS). OS of patients surviving at least 2 years from ASCT (Figure 1a) continued to remain superior for those attaining sCR (n=105, median: not reached) versus 70 months for the CR group (n=32; p=0.004). Among patients achieving sCR (n=109), OS of patients with sus-sCR (n= 75) at 6 months from ASCT is not reached (5-year OS=91%, 7-year OS=86%) versus median OS of 66 months (5-year OS=49%, 7-year OS=37%; p<0.0001) for those who had non-sustained-sCR (n=34) after ASCT (Figure 1b). Conclusion In our landmark analysis of patients with MM who survived at least 2 years from ASCT, those attaining sCR have a markedly superior outcome compared to those attaining standard CR. However, among patients attaining sCR, those with sustained sCR of 6 months or greater had the best outcome. Myeloma trials reporting response rates should identify patients achieving sCR and CR separately owing to markedly disparate outcomes of the two categories. Disclosures: No relevant conflicts of interest to declare.

AimsThe aims of this study were to review our 5‐year experience with clinical FISH testing for TP63 rearrangements using both TP63 break‐apart (BAP) and TBL1XR1/TP63 dual‐fusion (D‐FISH) probes to evaluate the frequency of TP63 rearrangements and the distribution of TBL1XR1 vs. alternate partner loci, and to assess whether both probe sets are necessary in all cases undergoing FISH testing.Methods and resultsA retrospective review of the Mayo Clinic cytogenetic database identified 470 patients evaluated by FISH testing for TP63 rearrangements in formalin‐fixed paraffin‐embedded (FFPE) tissue using both BAP and D‐FISH probes. Of these, 25 (5.3%) had TP63 rearrangements. All samples were being investigated for anaplastic large‐cell lymphoma or other T cell lymphoma subtypes. A TBL1XR1 partner was identified by D‐FISH in 12 (48%) of 25 cases. All cases positive by TBL1XR1/TP63 D‐FISH were also positive by TP63 BAP FISH.ConclusionThis is the largest series of TP63 rearrangements to date. The frequency of positive results among cases referred to a large reference laboratory for TP63 FISH testing was 5.3%. Approximately half of TP63 rearrangements have a TBL1XR1 partner. TP63 BAP FISH testing is sufficient for up‐front testing of FFPE tissue samples. However, because of the genomic proximity of the TP63 and TBL1XR1 loci, we recommend reflex TBL1XR1/TP63 D‐FISH testing in positive and equivocal cases.