Morice, William George

Understanding temporal dynamics of COVID-19 symptoms could provide fine-grained resolution to guide clinical decision-making. Here, we use deep neural networks over an institution-wide platform for the augmented curation of clinical notes from 77,167 patients subjected to COVID-19 PCR testing. By contrasting Electronic Health Record (EHR)-derived symptoms of COVID-19-positive (COVID pos ; n = 2,317) versus COVID-19-negative (COVID neg ; n = 74,850) patients for the week preceding the PCR testing date, we identify anosmia/dysgeusia (27.1-fold), fever/chills (2.6-fold), respiratory difficulty (2.2-fold), cough (2.2-fold), myalgia/arthralgia (2-fold), and diarrhea (1.4-fold) as significantly amplified in COVID pos over COVID neg patients. The combination of cough and fever/chills has 4.2-fold amplification in COVID pos patients during the week prior to PCR testing, in addition to anosmia/dysgeusia, constitutes the earliest EHR-derived signature of COVID-19. This study introduces an Augmented Intelligence platform for the real-time synthesis of institutional biomedical knowledge. The platform holds tremendous potential for scaling up curation throughput, thus enabling EHR-powered early disease diagnosis.

Abstract The IgVH mutation status is an independent predictor of time to treatment and survival in CLL. However, the biological basis of this difference is unknown. Clinical use of the IgVH mutation status as a prognostic marker is limited due to the technical difficulties of assessing this feature. As such, we probed for differences in protein expression by CLL cells with unmutated (UM) vs mutated (M) IgVH using phage peptide display libraries (PDPL). Methods: PDPL consists of phages engineered to express random peptides (7-mer) on the coat protein. From approximately 2x1011 phages displaying all possible permutations of 7-mer peptide, we selected phages binding to UM cells by incubation with 106 UM cells and elution of bound phages. Then, from numerous phages initially binding to UM cells, we subtracted phages binding to M cells by multiple incubations with M cells (106). Thus, the phages that bound only to UM cells were selected. The procedure was repeated multiple times to increase selection specificity. The peptide sequences displayed by selected phages were evaluated. We identified phage targets on UM cells by immunoprecipitation (IP) of CLL protein with specific phage and by sequencing of precipitated protein. The expression of target protein in CLL cells was confirmed by immunobloting and flow cytometry. Results: Sequencing of phages from the 3rd round of selection (UM v. M) revealed several peptides, with the most predominant being FPSAHFL. IP identified the cellular target for FPSAHFL as vimentin, an intermediate filament protein involved in cell motility and activation. The level of vimentin expressed by CLL cells varied between patient samples (n=15). UM CLL cases were found to express higher levels of vimentin (the mean MFI was 1002; SD 381), than cases of M CLL (mean MFI 547; SD 109), p=0.0128. To evaluate the prognostic significance of vimentin, we assessed vimentin expression by flow cytometry in a separate subgroup of 40 CLL patients. Archived cell samples collected between 6/2000 – 6/2001 were used. The median follow up was 81 months (40–233). Vimentin expression (MFI) as a continuous variable was a risk factor for a shortened time to treatment (TTT) with a proportional hazard ratio of 4.152 (95% CI 1.33–15.220, p=0.0317). Using MFI closest to the median (and rounded to 2 decimal places) as a cutoff, we stratified patients in high (n=21) and low (n=19) vimentin expression groups. The median times to treatment (TTT) in patients with high vs low level expression of vimentin were 2.8 and 12.9 years respectively, p=0.0025 (Fig.). Conclusion: Using novel proteomic technology, we found that CLL cells with unmutated IgVH expressed higher levels of vimentin than CLL cells with mutated IgVH. A high-level of vimentin expression defined by flow cytometry appears to be associated with high-risk disease. Validation of these findings could allow for the vimentin level to be used as a surrogate marker for expression of unmutated IgVH in CLL. Figure Figure

Abstract Background: Multiple myeloma (MM) is a plasma cell malignancy involving complex cytogenetic dysregulation of genes and heterogeneous expression of multiple B cell and plasma cell (PC) surface antigens. 60% of MM patients have cytogenetic translocations of the IGH locus. In 16% of myeloma patients, the partner oncogene is cyclin D1 on 11q13 causing t(11;14)(q13;q32) (Fonseca et al. Blood. 2002). This translocation is more common in patients with a lymphoplasmacytic morphology and confers a more favorable prognosis (Fonseca et al. Blood. 2003). A subset of MM patients (20%) harbor a clonotypic population of CD20+ bone marrow plasma cells (BMPC). These patients have a shortened survival time (SanMiguel et al. Br J Haematol. 1991). There is a strong association with CD20+ surface expression and t(11;14)(Robillard et al. Blood. 2003) and CD20+ PC has been suggested to be clonogenic and important in the pathogenesis of MM. A small Phase II study showed only a modest response to the humanized anti-CD20 monoclonal antibody rituximab in MM patients with CD20+PC (1 PR and 5SD) (Treon et al. J. Immunother. 2002). We report a response to treatment with rituximab in a MM patient with CD20+ BMPC and t(11;14)(q13;q32) by FISH. Case: The patient is a 68 year old male with a 1.5 year history of MM. Initial diagnosis of ISS stage I disease was made after a three year history of IgA kappa monoclonal gammopathy of undetermined significance (MGUS). At diagnosis of MM, he had symptomatic anemia Hgb10.5g/dL, rising serum IgA of 3950 mg/dL, serum m-spike of 4.1 g/dL (IgA kappa), PCLI (plasma cell labeling index) of 1%, and a small monoclonal IgA kappa with kappa fragment in the urine. BM showed 44% monoclonal kappa plasma cells with 90% CD20+,clonal PC on flow cytometry. Karyotype was normal; 46, XY, but FISH showed evidence of an IGH translocation t(11;14)(q13;q32) in 60% of PC. Immunohistochemical staining was positive for cyclin D1. Given the marked elevation of CD20+ PC and early stage of disease, initial treatment was employed with four weekly cycles of rituximab (375mg/m2). IgA fell from 4750 mg/dL to a nadir of 2990 mg/dL, (m-spike; 4.5g/dL to 3.2 g/dL) five weeks after completion of treatment. The monoclonal protein (MP) in the urine disappeared. Hgb improved to 12.5g, with erythropoietin. Three months later, IgA rose to 3260mg/dL (m-spike 3.2 g/dL) and urinary MP returned. The patient remained asymptomatic. A second course of weekly rituximab was started. IgA level and serum m-spike remained fairly stable over the next 7 months. All treatment was tolerated well except for initial transient rigors, fever, and nausea. Despite bi-monthly maintenance rituximab, the patient devloped a rising IgA of 4940 mg/dL, m-spike of 4.7, falling Hgb and a rising PCLI of 1.5%, 15 months after his original diagnosis of MM. Of particular concern is the development of new, unfavorable, cytogenetic aberrations by FISH with BMPC now showing deletion 13 in 93% and mutation of p53 (17p13) in 98%.100% show fusion of CCND1 and IGH and PC now only partially express CD20. Conclusion: This report suggests that MM patients with CD20+ BMPC and t(11;14)(q13;q32) may represent a target population for anti-CD20 therapy. Our report supports the concept proposed that targeting this clonotypic subset of B cells possibly interrupts a critical oncogenic pathway that is important in the pathogenesis of the clonogenic development of MM.

Abstract Acquired pure red cell aplasia (APRCA) is associated with a number of conditions including malignancies, infections and autoimmune disorders. APRCA also occurs in patients with T-LGLL. It is postulated that suppression of erythropoiesis in T-LGLL is related to the immune destruction of erythroid precursors by the LGL clone. We hypothesize that APRCA can be associated with clonal T-cell expansion without pathological evidence of T-LGLL. Methods: We identified patients who were diagnosed with APRCA and had clonal TCR gene rearrangements. Clinical course, bone marrow pathology and flow cytometry data were reviewed. Immunohistochemical studies were performed on available bone marrow biopsies using antibodies to CD3, CD8, CD20 and the cytotoxic granule proteins TIA-1 and granzyme B. Clonal TCR gene rearrangements were detected by PCR and Southern blot. The diagnosis of APRCA was based on the absence of erythroid progenitors, with intact granulo- and thrombopoiesis. A pathologic diagnosis of T-LGL leukemia was established by the presence of clonal TCR gene rearrangements and an immunophenotypically distinct CD8 positive T-cell population as previously described. The diagnostic flow cytometric features included abnormal patterns of T-cell antigen expression and aberrant co-expression of NK-cell antigens. Immunoperoxidase features supportive of a diagnosis of LGL were the presence of interstitial clusters or intravascular staining of cells positive for CD8 and TIA-1 and/or granzyme B. Results: We identified 28 patients with APRCA and the presence of clonal TCR gene rearrangements seen at Mayo Clinic Rochester between 7/1/1991 to 6/1/03. All patients presented with a transfusion dependent anemia (median hemoglobin 7.8 g/dL, range 3.6–10.3). Tissue was available for immunohistochemical studies for 21 cases. 13 of 21 patients (61%) had an immunophenotypically abnormal T-cell population which, in conjunction with the clonal TCR gene rearrangements were considered diagnostic of T-LGL. 8 patients (39%) had no pathological evidence of T-LGLL despite clonal TCR gene rearrangement studies. The most commonly used treatment consisted of oral cyclophosphamide which was used in 14 of 21 patients (8 and 6 in patients with and without pathological evidence of T-LGLL respectively). A normalization of hemoglobin was seen in 11 patients (6 and 5 in patients with and without evidence of T-LGLL respectively). Median duration of response was 30 months (range 22–120). None of 8 patients with APRCA and clonal TCR gene rearrangements without evidence of LGLL at the the time of initial diagnosis developed overt T-LGLL during follow up (median 64 months, range 30–118). Discussion: 39 % of patients with APRCA and evidence of clonal TCR gene rearrangements did not meet pathological criteria for diagnosis of T-LGLL. There was no apparent difference in disease presentation and response to therapy in patients with or without pathological evidence of LGLL. The significance of the presence of clonal TCR gene rearrangements in the absence of a detectable immunophenotypically abnormal T-cell population is unclear. It is possible that T-LGL was present which could not be detected by our analyses. Alternatively, the clonal TCR gene rearrangements could be indicative of a pertubation of the T-cell compartment related to an autoimmune disorder causing the APRCA. The fact that none of the patients developed progression to overt LGLL supports the latter possibility.

Abstract Purpose: Mantle cell lymphoma (MCL) is characterized by a t(11;14) resulting in overexpression of cyclin D1, a member of the phosphatidylinosital 3 kinase (PI3K) pathway. This study tested whether CCI-779, which inhibits the PI3K pathway at the level of the mammalian target of rapamycin (mTOR) could produce tumor responses in patients (pts) with MCL. Patients and Methods: Eligible pts had biopsy-proven, cyclin D1 positive MCL and had relapsed or were refractory to therapy. Pts received CCI-779 250 mg IV every week as a single agent. Pts were re-staged after 1 cycle (4 doses) and every 3 cycles thereafter. Pts with a tumor response after 6 cycles were eligible to continue drug for a total of 12 cycles or 2 cycles after complete remission (CR) and then were observed. Results: Thirty-five pts were enrolled and evaluable for toxicity; 1 patient had MCL by histology but was cyclin D1 negative and ineligible for efficacy evaluation. The median age was 70 years (range, 38–89), 91% were stage 4, and 69% had ≥ 2 extranodal sites. Pts had received a median of 3 prior therapies (range, 1–11) and 54% were refractory to their last treatment. The overall response rate was 38% (13/34) with 1 CR (3%) and 12 PRs (35%), surpassing the pre-defined criteria for a promising agent. Responses tended to occur rapidly with median time to response of 1 month (range, 1–8). To date, 26 patients have progressed, with a median time-to-progression of 6.8 months (95% CI: 3.8 – 9.7). Median duration of response for the 13 responders was 5.7 months (95% CI: 5.2 – 13.2). Overall, 32 out of 35 patients who received treatment had grade 3 or 4 toxicity. The most common toxicities were hematologic with grade 3 (n=24) or grade 4 (n=4). Thrombocytopenia was the most frequent grade 3/4 toxicity (n=25) and the largest cause of dose-reductions, although counts typically recovered within one week. Only 4 patients could tolerate sustained 250 mg per week throughout their treatment (including one who went on to alternate treatment after 1 cycle) and the median dose/month was 175 mg. Conclusions: Single-agent CCI-779 has substantial anti-tumor activity in relapsed MCL. This study demonstrates that agents, which selectively target cellular pathways dysregulated in MCL cells can produce therapeutic benefit. The high response rate warrants further studies of this agent in MCL, but the high incidence of hematologic toxicity suggests that a lower dose should be explored. CCI-779 at 25mg is currently being evaluated in MCL through an NCCTG trial

AbstractEnumeration of blasts and promonocytes is essential for World Health Organization (WHO) classification of myelomonocytic neoplasms. The accuracy of distinguishing blasts, promonocytes and monocytes, including normal vs abnormal monocytes, remains controversial. The objective of this analysis is to assess concordances between experienced hematopathologists in classifying cells as blasts, promonocytes, and monocytes according to WHO criteria. Each of 11 hematopathologists assessed glass slides from 20 patients [12 with chronic myelomonocytic leukemia (CMML) and 8 with acute myeloid leukemia (AML)] including blood and BM aspirate smears, and limited nonspecific esterase (NSE) stains. All cases were blindly reviewed. Fleiss’ extension of Cohen's kappa for multiple raters was used on these variables, separately for peripheral blood (PB) and bone marrow (BM). Spearman's rank correlation was used to assess correlations between each pair of hematopathologists for each measurement. For the classification based on the sum of blasts and promonocytes in the BM, Fleiss’ kappa was estimated as 0.744. For PB, categorizing patients according to the sum of blasts and promonocytes, Fleiss’ kappa was estimated as 0.949. Distinction of abnormal monocytes from normal monocytes in PB did not achieve a good concordance and showed strong evidence of differences between hematopathologists (P < .0001). The hematopathologists achieved a good concordance rate of 74% in CMML vs AML classification and a high k rate, confirming that criteria for defining the blasts equivalents (blasts plus promonocytes) could be applied consistently. Identification of monocyte subtypes (abnormal vs normal) was not concordant. Our results support the practice of combining blasts/promonocytes into a single category.

Abstract The peripheral blood absolute lymphocyte count (ALC) on day 15 after autologous stem cell transplantation (ASCT) has been shown to be an independent predictor for overall survival (OS) for many malignancies including acute myelogenous leukemia (AML), breast cancer, multiple myeloma (MM), primary systemic amyloidosis, and Hodgkin’s and non-Hodgkin’s lymphoma (NHL). A recent report (Dean et al. BMT2005; 36, 1049–1052) suggested that infused autograft dendritic cells (DC) affect survival post-ASCT in NHL. Thus, DC recovery at day 15 post-ASCT was assessed and correlated with OS. Preliminary data from an ongoing prospective study of 28 NHL patients post-ASCT are reported. Absolute DC at day 15 was analyzed by four color flow cytometry using antibodies to CD3, CD14, CD16, and CD19. In this approach lymphocytes and DCs were initially gated by their similar forward and side light scatter characteristics; DCs were then identified as cells in this gate that lacked staining for the lymphocyte antigens CD3, CD16, and CD19 and the monocyte antigen CD14. The percentage of antigen negative cells cells in the lymphocyte gate was then multiplied by the coincident peripheral blood absolute lymphocyte to determine the absolute DC count. Survival was then analyzed using the Kaplan-Meier method. With a median follow-up of 18 months, patients recovering a DC of 10 cells/μl or above experienced superior median OS versus those who did not (not reached vs 21 months, p < 0.02, Figure 1). This study shows that an immunocompetent immune system at day 15 (not only ALC recovery, but also DC recovery) correlates with survival in NHL patients undergoing ASCT. Figure Figure

Abstract Abstract 3937 Poster Board III-873 Introduction Mantle cell lymphoma (MCL), defined by the pathognomic CCND1/IGH translocation, commonly presents with lymphadenopathy and has an aggressive clinical course with poor survival. However, a minority of patients with MCL present with lymphocytosis without substantial adenopathy. The clinical and pathologic features of this group of patients are not currently well understood. Methods Patients with monoclonal B-cell lymphocytosis, positive CCND1/IGH translocation status by FISH analysis and absence of lymphadenopathy were identified in our institutional B-cell lymphoproliferative disorder database. A comprehensive review of clinical, laboratory, and histopathologic features was conducted. Results of ancillary immunophenotypic, molecular genetic, and cytogenetic studies were reviewed. Univariate survival analysis was performed using the method of Kaplan and Meier. Result We identified a total of 35 patients meeting the selection criteria (10 female and 25 male; median age 66 yrs, range 41-86). The median absolute lymphocyte count at presentation was 8.7 × 109/L (range 2.7-180). Eleven patients subsequently developed adenopathy (MCL-LN) while 24 patients had persistent lymphocytosis without adenopathy (MCL-PB). There were no significant differences in age, gender, absolute leukocyte count, percent bone marrow involvement by lymphoma, or immunophenotypic features of the neoplastic B-cells between these 2 subgroups at initial evaluation. All 11 MCL-LN (100%) and 14 of the 24 MCL-PB patients (58%) had splenomegaly at presentation. Morphologic and immunophenotypic features in peripheral blood (n=35), bone marrow (n=34), lymph node (n=7), spleen (n=7) and other involved tissues (n=4) were typical of MCL in 34 patients. One patient had an unusual disease recurrence resembling hairy cell leukemia, but was retained in the analysis given the persistence of the CCND1/IGH abnormality and molecular evidence of clonal identity with previous specimens. All patients with MCL-LN and 12/24 (50%) of patients with MCL-PB received therapy including R-CHOP, cladribine, or rituximab. The remaining 12 MCL-PB patients (50%) were managed expectantly. Patients with MCL-PB (median survival of 156 months from diagnosis) had a significantly better survival than patients with MCL-LN (13 months) regardless of splenic involvement (P=0.0002) (Figure 1). Conclusion Among patients with MCL presenting in leukemic phase without adenopathy, we have identified 2 subgroups with distinct clinical outcomes. Patients who do not develop subsequent lymph node involvement (MCL-PB) have a generally more favorable clinical outcome. These findings imply fundamental differences in the pathobiology and molecular oncogenesis between these subgroups, suggesting the presence of distinct MCL entities. Disclosures: Zent: Genentech, Bayer, Genzyme, Novartis: Research Funding. Shanafelt:Genentech: Research Funding; Hospira: Membership on an entity's Board of Directors or advisory committees, Research Funding; Polyphenon E International: Research Funding; Celgene: Research Funding; Cephalon: Research Funding; Bayer Health Care Pharmaceuticals: Research Funding. Kay:Gnentch: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Hospire: Research Funding; Polyphenon Pharma: Research Funding; Sanofi-Aventis: Research Funding; Biogenc-Ides: Membership on an entity's Board of Directors or advisory committees; Genmab: Membership on an entity's Board of Directors or advisory committees. Witzig:Novartis: Research Funding.

Abstract Background The presence of circulating plasma cells (PCs) in multiple myeloma (MM) is a known poor prognostic marker. Prior studies have utilized a technically challenging slide-based immunofluorescence technique to detect and quantify the presence of circulating PCs which was not widely adapted in clinical practice. More recently, the routine use of flow cytometry has provided the opportunity to quantitatively assess circulating PCs in MM patients with relative ease. We report the prognostic value of quantifying circulating clonal PCs using multiparametric flow cytometry in MM patients with relapsed disease. Methods We evaluated all MM patients seen at the Mayo Clinic, Rochester from 2009 to 2011 with previous or ongoing relapsed disease and who had their peripheral blood samples evaluated by flow cytometry. Each blood sample had its peripheral blood mononuclear cells isolated by ficoll gradient and stained with antibodies to CD45, CD19, CD38, CD138 and cytoplasmic Kappa and Lambda Ig light chains. A six-color multi-parameter flow cytometer (Becton Dickinson FacsCantos II) was used to examine each sample with a target of detecting 150,000 events (cells) that was then analyzed using the Facs Diva Software. Plasma cells were selectively analyzed through combinatorial gating using light scatter properties and CD38, CD138, CD19, and CD45. Normal PC's were then separated from clonal plasma cells based on the differential expression of CD45, CD19 and polytypic Ig light chains. The clonal plasma cells detected were reported out as the number of clonal events/150,000 collected total events. For those samples where less than 150,000 events were gated or examined, the number of final clonal events was adjusted to 150,000 events. Survival analysis was performed by the Kaplan-Meier method and differences in survival assessed using the log rank test. Results There were 647 consecutive patients with a history of treated MM who had a peripheral blood flow cytometry as part of their routine clinical evaluation. The median patient age was 62 years (29-88) and 55% were male. The median time since diagnosis was 12 months (range: 1-363) and the median number of lines of treatment received was 2 (1-11). There were 81 (13%) patients with clonal circulating PCs with a median of 368 cells (4 – 133,464). The 2-year overall survival (OS) for the 81 (13%) patients with any circulating PCs was 17% compared with 65% for those with none (P<0.001). The presence of circulating clonal PCs was associated with high-risk disease by FISH (P <0.001) as well as higher PCLI (P <0.001). We then correlated the presence of circulating clonal PCs with the disease status at flow cytometry assessment. Among the study patients, only 145 (22%) had actively relapsing disease with the remaining 502 (78%) in a plateau including patients in CR. Circulating clonal PCs were more likely to be detected in patients with actively relapsing disease compared with plateau phase (43% vs. 4%, P < 0.001); none of the CR patients and <5% of the remaining plateau phase patients had any detectable circulating clonal PCs. We then restricted the analysis to the actively relapsing patients; the best cutoff predicting 1-year mortality by ROC analysis was 100 events. Based on this, we defined >=100 events as a cutoff for defining the prognostic role of circulating clonal PCs in actively relapsing patients. The median OS for those with >=100 clonal PC events was 12 months compared with not reached for those with <100 events (p<0.001; Figure 1 ). Among patients with actively relapsing disease, >= 100 circulating PCs was associated with a higher ISS stage, plasma cell labeling index and bone marrow PC% compared with those with <100 circulating PCs. In a multivariable model, only LDH > 222 (HR: 2.08, P = 0.045) and >= 100 circulating PCs (HR: 2.48, P = 0.048) were found to adversely affect OS in actively relapsing patients. Conclusion The utilization of flow cytometry to quantify circulating clonal PCs in patients with relapsed MM appears to have significant prognostic relevance. In patients with actively relapsing disease, >= 100 circulating PCs predicted for worse OS with a median of 12 months. Future studies are needed to determine if this would allow an opportunity to develop a more risk adapted approach for patients with relapsed disease. Disclosures: Kumar: Celgene: Consultancy, Research Funding; Millennium: Consultancy, Research Funding; Onyx: Consultancy, Research Funding.

Abstract Abstract 4995 Background: Multiple myeloma results from an accumulation of monoclonal nonproliferating plasma cells arising from a small subpopulation of proliferating myeloma cells. In an effort to optimize detection of the human myeloma cell growth fraction and obviate the need for slide review, a novel FC strategy was developed combining elements of light chain restriction, surface antigen expression, and ploidy analysis. Methods: Bone marrow cells from 41 patients with plasma cell proliferative disorders were lysed with ACK and resuspended in 3% BSA. Cells were stained using a 6-color assay with anti-CD45, anti-CD38, anti-CD138, and anti-CD19. Cells were washed and 100 ul Caltag solution A was added for 15 min. Cells were washed and 100 ul of Caltag solution B, anti-kappa and anti-lambda were added for 10 min. Cells were washed and 100 ul PBS and 3 ul RNAse are added for 15 min. Cells were washed and 400 ul of a 1:1000 solution of 3uM DAPI in Tris 0.1% NP-40 was added. Cells were incubated at 4°C for 45 minutes before running on a FACSCanto instrument for ploidy determination. All patients were analyzed both by flow cytometry and the slide based plasma cell labeling index. Results: Forty-one patients were studied; 34 demonstrated a proliferative fraction and 7 had too few plasma cells for analysis after therapy. Of the 34 patients, 6 had MGUS/SMM, 5 newly diagnosed MM, 7 amyloid, and 16 were treated MM. The mean percent proliferating cells were 1.1% (range 0 – 8.6%) with PCLI and 1.4% (range 0.1 – 12.7%) by flow. The correlation between PCLI and flow gave a RSquare value of 0.54. Twelve patients with a PCLI of 0% had a flow proliferation between 0.1 – 1.4% (mean 0.49%). Treated patients received lenalidomide, dexamethasone, bortezomib, and/or autologous transplantation. All 16 treated myeloma patients with adequate plasma cells had a flow proliferation between 0.2 – 12.7% (mean 2.2%). Conclusion: Flow cytometry offers a useful way to detect the proliferative myeloma component at diagnosis and after treatment. The continued presence of proliferating myeloma cells after treatment may explain why most patients relapse and offers another important marker to monitor and cell population to target in patients with active disease. Disclosures: Kumar: Celgene: Consultancy, Research Funding; Millennium: Research Funding; Merck: Consultancy, Research Funding; Novartis: Research Funding; Genzyme: Consultancy, Research Funding; Cephalon: Research Funding.