Citations

Abstract Detection of an M-protein (monoclonal immunoglobulin) has been used to diagnose and monitor multiple myeloma (MM). As therapies for MM have improved, more sensitive methods have been used to define response: immunofixation electrophoresis (IFX) of serum and urine, normalization of the serum immunoglobulin free light chain (FLC) ratio, and high sensitivity flow cytometry to detect clonal plasma bone marrow cells. It is hoped that these more sensitive approaches will differentiate those patients with minimal residual disease (MRD) versus no residual disease (NRD), that later which could mean a cure. Flow cytometry of plasma cells requires bone marrow aspiration, which is inconvenient and expensive and is potentially limited by sampling bias. More sensitive methods to differentiate MRD from NRD using serum would be advantageous. We have developed a sensitive test for the presence of the monoclonal antibody produced by the plasma cells which may serve as a substitute for invasive bone marrow biopsy. Briefly, patient serum is enriched for immunoglobulins (Ig) and the Ig light chains are decoupled from the heavy chain by reduction with DTT. The mass distribution of the light chains is resolved using a micro LC-ESI-Q-TOF mass spectrometry and the presence of the M-protein is detected as a spike in the mass distribution. In addition to the detection, the accurate mass measurement of the light chain serves as a unique individualized marker which can aid in detection in subsequent patient monitoring. We have termed this method: monoclonal-immunoglobulin-Rapid-Accurate-Mass-Measurement (miRAMM). By spiking monoclonal immunoglobulins into human serum, we have demonstrated that miRAMM is approximately 1000x more sensitive than SPEP at detecting M-proteins. Initial results on 21 patients in stringent complete response (sCR) demonstrated that 67% (n=14) had detectable malignant specific clones by miRAMM. Given these promising results we have extended the method to a larger series of myeloma patients for whom we had long term follow-up and serum samples prior to treatment and at 6-12 months status post stem cell treatment. The results of this data will be correlated to the clinical outcomes for these patients. Early results demonstrate the potential of miRAMM to be a more sensitive, cost effective approach to detect MRD compared with current methods. Disclosures Murray: Mayo Clinic: Patent Application filed Patents & Royalties. Barnidge:Mayo Clinic: Patent filed Patents & Royalties.

Abstract Abstract 2877 FLC assay measures circulating unbound k and l light chains and is of diagnostic and prognostic value in plasma cell disorders. Normalization of FLC ratio is considered a higher level of complete response (CR) in MM but this has not been well validated prospectively. HLC is a novel antibody based assay that targets the unique junctional epitopes between the heavy chain and light chain constant regions of intact immunoglobulin (Ig) molecules. It separately measures in pairs the light chain types of each immunoglobulin class generating ratios of monoclonal Ig/background polyclonal Ig concentrations (i.e IgGκ/IgGλ, IgAκ/IgAλ and IgMκ/IgMλ); potentially simplifying assessment of monoclonal protein response. To assess the prognostic impact of these assays and to correlate them with electrophoretic/immunofixation (SPE/IFE) assessment, we analyzed 497 stored serum samples from patients enrolled in the Blood and Marrow Transplant Clinical Trials Network (BMT CTN) 0102 clinical trial, sponsored by the NHLBI and NCI, of tandem autologous (autoHCT) vs. tandem autoHCT- allogeneic (alloHCT). Samples were collected prior to the first autoHCT and analyzed for FLC (Freelite™) and HLC (Hevylite™) at The Binding Site, UK. Corresponding disease status determination was centrally performed by an expert data review committee using uniform response criteria and correlated with FLC and HLC results. HLC remission was defined as normalization of composite heavy and light chain ratios across all 3 measured heavy/light chain pairs or the normalization of clonal isotype with normal ratios of uninvolved pairs. The demographics of 497 patients with HLC/FLC samples at baseline were concordant with the main study and showed similar patient proportions from the 2 study arms. Of the 211 pts with baseline SPE response better than or equal to a very good partial response (>VGPR), 188 also had an HLC remission (Sensitivity=89%). Comparison of the HLC remission with the >VGPR disease state also identified a specificity of 52%, positive predictive value (PPV) of 58% and a negative predictive value (NPV) of 87%. Similarly, all 56 patients in complete remission (CR) by SPE/IFE were in HLC remission. Compared with conventional CR assessment, sensitivity of HLC remission was 100%, specificity 39%, PPV and NPV values of 17% and 100% respectively. FLC remission correlated with >VGPR disease state had a sensitivity of 47%, specificity of 81% and a PPV and NPV of 64% and 67% respectively. Multivariate models for post transplant progression free survival (PFS) indicated that baseline disease response (>VGPR vs. partial remission (PR) or<PR) was associated with longer PFS. Adjusted models including baseline response, myeloma stage and study arm were used to compare the predictive utility of HLC and FLC assays. There was a lower risk of treatment failure (HR 0.74, p=0.02) and superior PFS for patients who achieved an HLC remission. When stratified by baseline disease response states, there was no additional prognostic impact for HLC remissions on PFS. Normalization of FLC ratio among patients with >VGPR disease state did not impact PFS (HR 0.96, p=0.83). Abnormal HLC after induction therapy has a high negative predictive value (100%) for identifying patients not achieving CR by uniform response criteria and is also associated with shorter PFS after transplant. FLC ratio normalization had no impact suggesting that stringent CR criteria may need further validation. Disclosures: Krishnan: Celgene: Speakers Bureau; Millenium: Speakers Bureau. Alvi:the binding site: Employment. Harding:The Binding Site Group Ltd: Employment. Maloney:Cellgene: Consultancy.

Abstract Proteomics with great sensitivity and specificity effectively analyzes proteins by prior tryptic digestion and subsequent analysis by LC-MS/MS of the tryptic digest. We have utilized this approach in the development of a LC-MS/MS method to characterize minimum residual disease in multiple myeloma. The abundant antibodies produced by multiple myeloma plasma cells are identical and appear as a spike (M-spike) upon protein electrophoresis. The M-spike and histological examination of the bone marrow constitute part of the myeloma diagnostic repertoire. Upon treatment, myeloma cells and the antibodies they produce are reduced in number and amount and become increasingly hard to detect. The bone marrow biopsy serves as the “gold standard” test for clinical remission. We have developed a sensitive test for the presence of the monoclonal antibody produced by the plasma cells which may serve as a substitute for invasive bone marrow biopsy. We have focused on tryptic peptides comprising the variable CDR regions of the Ig light chains that are unique to each patients antibody clone. Utilizing 2-5 µL of patient plasma/serum from the initial M-spike sample we have utilized SDS-PAGE to yield a crudely purified immunoglobulin light chain. The light chain band is isolated, reduced, alkylated and trypsin digested with subsequent LC-MS/MS analysis to identify CDR specific tryptic peptide(s). These can be identified as variable peaks (elution time and mass) in a base peak ion chromatogram where constant region peptides of either lambda or kappa light chains (clone dependent) serve as “internal standards” for identifying the CDR tryptic peptides. The peptide’s mass and its corresponding MS/MS spectra are unique to this CDR tryptic peptide and this patient’s clone. The unique diagnostic peptide is isolated in subsequent samples by immunoaffinity purification of the target kappa/lambda clone, SDS-PAGE separation and LC-MS/MS analysis of the light chain gel band. An extracted ion chromatogram is generated based upon the CDR peptides identified in the initial analysis of the M-spike sample. In patients in clinical remission the presence of a significant signal from the targeted peptides indicates that targeting a CDR peptide from the M-spike protein is more sensitive than currently available diagnostic tools including immunofixation. Comparison of this test to the gold standard bone marrow biopsy will be examined. Disclosures: Barnidge: Mayo Foundation: provisional patent application for technology, provisional patent application for technology Patents & Royalties.

Abstract Active cancer is an independent VTE risk factor (overall 6- to 9-fold increased risk) and accounts for almost 20% of all VTE in the community, but which cancer patients are at risk for VTE is largely unknown. Reportedly, VTE risk varies by tumor site, and cancer of the ovary, pancreas, colon, stomach, lung, prostate, and kidney convey particularly high VTE risk. Objective: To estimate VTE risk by tumor site. Methods: We enumerated observed cancers by tumor site for Olmsted County, MN active cancer patients with incident VTE over the seven-year period, 1991–1997 (n=152). We used 1991–1997 State Surveillance, Epidemiology, and End Results (SEER) data for Iowa to estimate the expected age-specific prevalence of cancer by tumor site in Olmsted County. VTE risk ratios (RR) for each tumor site were estimated by dividing the observed number of cancers by the expected number (calculated as the product of the SEER prevalence and the number of incident VTE cases in the age stratum). Results: For our population of 1991–1997 VTE cases, all tumor sites had RR > 5.0 (range 5.2 to 37.3, all p-values<0.05). Compared to published overall VTE odds ratios of 6–9 for active cancer compared to no cancer, the RR for some tumor sites were particularly increased. A Chi-squared test of heterogeneity of the RR across sites was highly significant (p-value<0.001). Three rare cancer sites - pancreatic cancer, lymphoma, and brain cancer - had unusually high RR (all RR>25). The high number of VTE cases with lymphoma was not due to catheter-related arm vein thrombosis. Liver, leukemia, other gastrointestinal (esophagus, small intestine, gallbladder, other biliary) and other gynecologic (primarily cervical) cancers had over twice the baseline risk (i.e., RR>17.0). On the other hand, the RR for many common cancers (breast, colorectal, ovary, lung, prostate) were essentially the same as the overall baseline risk (all had 9.5<RR<12.0). Conclusions: In contrast to previous reports, pancreas, lymphoma, brain, liver, leukemia, other gastrointestinal, and other gynecologic cancers have the highest VTE risk. Prior estimates of VTE risk by tumor site may have been biased by studies of prevalent cancers among patients hospitalized in tertiary care centers.

Abstract Background: Neutropenia is the most common predisposing factor that increases the susceptibility of cancer patients (pts) to infection. The use of fluoroquinolones (FQs) as prophylaxis during chemotherapy-induced neutropenia has been shown to decrease the frequency of gram-negative (GN) infections (Cullen et al. NEJM 2005) with the benefit of reduced infection-related mortality in neutropenic pts with cancer (Bucaneve et al. NEJM 2005) and was instituted as part of our institution-wide standard clinical practice in January 2006. The widespread use of FQs for prophylaxis of pts with neutropenia and hematologic malignancies raises concerns about the evolving resistance of organisms. Methods: This retrospective observational study compared acute myeloid leukemia (AML) and acute lymphoid leukemia (ALL) pts, ages 18 and older who were admitted to the hematology service and received levofloxacin prophylaxis (LEVP) within 60 days of admission with those who were admitted but did not receive LEVP during the period of chemotherapy-induced neutropenia. Pts had to have a positive sterile site culture up to 96 hours prior to admission excluding Staphylococcus coagulase negative, Propionibacterium, Corynebacterium, and other common colonizing organisms. Analysis also compared the rates of Methicillin-resistant Staphylococcus aureus (MRSA) infections, positive Vancomycin-resistant Enterococci (VRE) swabs, and positive Clostridium difficile cultures and evaluated them for a correlation LEVP. Results: A total of 213 pts were evaluated between September 2004 and May 2007. Ninety-four pts received LEVP and 119 did not. Patient characteristics were similar between groups. There was a shift from almost equal incidence of gram-positive (GP) and GN cultures in the group without prophylaxis (51% vs 49%, respectively) to a predominance of GP cultures with LEVP (68% vs 32%, respectively). There was a significant decrease in the number of sterile site cultures of GN organisms (n = 94 vs 37, respectively), while cultures of GP organisms remained similar (n = 98 vs. 77, respectively). GN organisms in sterile site cultures occurred less often in the LEVP group, however; the incidence of resistance to levofloxacin in GN was higher (32% vs 15%), particularly the susceptibility profiles of Pseudomonas sp., Escherichia coli, and Stenotrophomonas maltophilia. Both groups had equal cultures of Staphylococcus aureus, but the group receiving LEVP had a greater incidence of MRSA (55% vs 30%). Rates of positive VRE swabs declined and had no apparent correlation with the use of levofloxacin as prophylaxis. There were more documented positive Clostridium difficile cultures in the pts receiving LEVP (29% vs 22%, respectively), but rates of Clostridium difficile have shown a constant increase throughout the institution; therefore, LEVP should not be considered the sole contributing factor to an increased rate of positive cultures. Conclusions: The epidemiology and microbial susceptibility profile of positive sterile site cultures of acute leukemia pts receiving LEVP during chemotherapy-induced neutropenia differed from those that did not. The LEVP group had a decrease in the absolute number of sterile site cultures, number and percent of GN sterile site cultures. There was an increase in GN organism resistance to levofloxacin and the incidence of several GP organisms increased with the number of GP organisms remaining constant.

Abstract Abstract 3893 Background: When screening for clonal disease, the kappa (k) to lambda (l) FLC ratio (FLC-R) is employed to correct for both impaired catabolism (renal function) and non-specific production (generalized immune overstimulation). This adjustment makes it possible to identify patients with relative imbalances between k and l levels, which typically qualifies for clonal excess and has been of value in screening for and prognosticating in patients with most clonal plasma cell disorders. We previously performed a population-based study among Olmsted County residents to ascertain the prevalence of monoclonal gammopathy of undetermined significance (MGUS) and light chain MGUS. We hypothesized that by using this cohort, we could identify whether the FLC assay provides information that would be prognostic in a general population of people 50-years and older. Methods: The Olmsted MGUS prevalence cohort was comprised of 21,463 of the 28,038 enumerated individuals over the age of 50 who were living Olmsted between 1/1/95 and 11/21/2003. The final sample size of individuals for the present study was 15839 due to patient losses secondary to blinding, inadequate sample to perform the FLC assay, and known MGUS or LC-MGUS. For the multivariate analyses, another 772 were excluded due lack of coincident creatinine measurement. The FLC measurements were performed using the FLC assay (Binding Site, Birmingham, UK). The respective reference ranges for k FLC and l FLC are 0.33–1.94 mg/dL and 0.57–2.63; therefore, the reference range for the sum of k and l FLC (S FLC) is 0.90–4.57 mg/dL. Survival time was calculated from the time of sample ascertainment. Results: Forty-five percent of the cohort was male. The median age was 63 years (range 50, 109). On univariate analysis, the hazard ratio for death for those patients with the highest decile of S FLC relative to the other 90% of patients in the cohort was 4.3 (95%CI 4.01, 4.62), Figure 1. Because serum immunoglobulin FLC rise with age and with renal insufficiency, a multivariate analysis was performed to exclude the possibility that S FLC was merely a surrogate for these other parameters. Table 1 shows both univariate and multivariate risk for death. With these other variables included, the hazard ratio for death with highest S FLC decile was lower, but remained significant; hazard ratio, 2.0 (95%1.88, 2.2). Conclusions: The finding that S FLC above the normal range (i.e. highest decile) is associated with inferior overall survival among individuals above the age of 50, excluding patients with known MGUS or LC-MGUS, is important and merits further investigation. Although there is an association between S FLC, renal function, gender, and age, excess risk of death still exists after adjusting for these risk factors on multivariate analysis. The mechanism by which S FLC predicts for outcomes is uncertain, but one could postulate that conditions resulting in overactivation of the immune system contributes to excess risk of death. Whether the S FLC adds above and beyond other conventional inflammatory markers like ESR or CRP cannot be determined by the present study, but is worthy of further investigation. Disclosures: Dispenzieri: Celgene: Honoraria, Research Funding; Binding Site: Honoraria. Off Label Use: No FDA approved indication. Kumar:Celgene: Consultancy, Research Funding; Millennium: Research Funding; Merck: Consultancy, Research Funding; Novartis: Research Funding; Genzyme: Consultancy, Research Funding; Cephalon: Research Funding. Mead:Binding Site: Employment. Bradwell:Binding Site: Equity Ownership, Patents & Royalties.

Abstract Abstract 54 B-cell chronic lymphocytic leukemia (CLL) is characterized by the progressive accumulation of CD5+ B-lymphocytes in the peripheral blood, lymphoid organs and bone marrow. Despite aggressive therapy, CLL is still incurable partly because of intrinsic defect in apoptosis induction. Deregulated expression of protein kinases by gene deletion, mutation, or amplification has been found to be important for tumor initiation and progression involving cancer cell proliferation, survival, motility, and invasiveness as well as tumor angiogenesis and chemotherapy resistance. Because of their critical functions in oncogenesis, protein kinases have been at the forefront of targeted cancer therapy development since the 1980s. A novel receptor tyrosine kinase (RTK) Axl has been reported to be overexpressed in several types of human cancers including colon, prostatic, thyroid, breast, gastric, renal and lung. Indeed, our recent investigation (ASH 2009, Abstract #2368) identified Axl to be constitutively phosphorylated in CLL B-cells obtained from a majority of CLL patients. We wished to examine whether the constitutively phosphorylated Axl plays a pivotal role in regulating leukemic CLL B-cell survival and could be a potential target to treat this disease. We used freshly isolated purified CLL B-cells after obtaining informed written consent from the patients. Expression status of various kinases in relation to Axl expression and their functional involvement with this novel RTK to drive downstream cell survival signaling pathway(s) were analyzed in CLL B-cell lysates by immunoprecipitation/Western blot analyses using specific antibodies. Finally, we evaluated the functional importance of Axl in CLL by employing two RTK inhibitory agents (Bosutinib [SKI-606] and R428) of different specificity and affinity for receptor tyrosine kinases in order to target Axl and determined the impact on apoptotic/cytotoxic effects on CLL B-cells by flow cytometric analysis. In some experiments, we used bone marrow stromal cells to evaluate if they could diminish the impact of the RTK agent R428. To further our initial examination of Axl status in CLL, we assessed the expression of phosphorylated-Axl (P-Axl) in freshly isolated CLL B-cells by Western blot analysis. Indeed, we detected differential levels of P-Axl in CLL B-cells (n=10). Further analysis revealed that the expression of P-Axl was associated with co-expression of other constitutively phosphorylated kinases/enzymes including Src family kinases (SFKs), PI3K, SyK/ZAP70 and PLC-g2 in CLL B-cells. Importantly, we found by immunoprecipitation of Axl and subsequent Western blotting that these intracellular signaling molecules were complexed with P-Axl in primary CLL B-cells. Further analysis using a siRNA approach targeting Axl suggests that phosphorylation of Axl is an upstream event of SFK-activation in CLL B-cells indicating a pivotal role of Axl in regulating CLL B-cell survival. Finally, when Axl and Src kinases were targeted by a Src/Abl kinase inhibitor, SKI-606 (dose range 2.5–20mM) or the specific-inhibitor of Axl, R428 (dose range 0.5–10 mM) robust induction of CLL B-cell apoptosis was observed in both a dose- and time-dependent manner (Figure). Although both RTK inhibitory agents showed clear induction of apoptosis in CLL B-cells, R428 was found to be the most potent in inducing apoptosis exhibiting an IC50 ∼4-fold lower than SKI-606. Furthermore, we have observed that R428 could target P-Axl resulting in inhibition of SFK-activation further suggesting that Axl regulates SFK-activity in CLL B-cells. Interestingly, R428-induced apoptosis in CLL B-cells (doses of 1.0 mM and 2.5 mM) was significantly inhibited when these leukemic cells were co-cultured with bone marrow stromal cells, but when we tested a higher dose (5 mM) of R428 this stroma-mediated protection was overcome. Further studies are underway to test R428 in combination other chemotherapeutic agents. Thus, we have identified a novel RTK, Axl, in CLL B-cells which appears to work as a docking site for multiple non-RTKs and drives cell survival signals. These findings indicate a unique therapeutic target for CLL treatment. Importantly, there are currently several Axl inhibitory agents that are available to be tested in CLL patients. Disclosures: Holland: Rigel: Employment.

Abstract Background: Current laboratory methods for detection of monoclonal gammopathies include a panel of serum protein electrophoresis (SPEP), immunofixation electrophoresis (IFE) and serum free light chain quantitation (FLC). Our group has recently described a new assay based on matrix assisted laser desorption ionization time of flight (MALDI-TOF) mass spectrometry (MS) which is capable of detecting, isotyping and quantitating M-proteins in a single assay. The basic principle of the method involves leveraging the unique mass resulting from light chain (LC) Ig gene rearrangement in B-cells. In a similar fashion to SPEP, the mass distribution of LCs after dissociation from their heavy chains can be examined for the presence of an over expressed light chain. In this study we retrospectively compared the MALDI-TOF MS method to SPEP, IFE and Hevylite ratios for monitoring patients with monoclonal gammopathies. Methods: Serum from patients who had at least 1 diagnostic and 4 serial follow-up samples was enriched for IgG, IgA, IgM, kappa and lambda using nanobodies. After disassociating the heavy and light chains by reduction, the five purified samples were spotted onto a Bruker Microflex MALDI plate. Automated acquisition (~10 seconds/sample) was performed and the five LC mass spectra from each enrichment were overlaid. M-proteins were detected, quantitated and isotyped by the presence of distinct peaks (m-spike) within LC mass to charge regions. The serial patient samples were then measured by MALDI-TOF and a comparison of results was made to previous aquired data. The results were then analyze in light of clinical and lab data in order to evaluate the ability of the MALDI-TOF MS method to monitor patients with monoclonal gammopathies. Results: In M-protein positive patient samples, serial dilution revealed MALDI-TOF MS to have ~10-times lower limit of detection than IFE. M-protein isotype in the cohort by MALDI-TOF MS was 100 percent concordant with the isotype from IFE. The MALDI TOF M-protein quantitation was linear over a clinically acceptable range (0.1 to 6 g/dL) and had improved linearity over SPEP at lower M-protein levels. M-proteins quantitation by MALDI-TOF MS compared well with SPEP with a slope of 1.16 (R2 -0.93). Hevylite Ig ratios for each isotype were statistically similar to those from MALDI-TOF MS demonstrating the ability of the MALDI to measure isotype suppression. For some patients, the MALDI method was able to detect M-proteins in patients with normal Hevylite ratios. Finally, the results for each patient were then compared over the course of monitoring. The time evolution change in M-protein concentration was similar among the three methods with the exception of a few samples in which the MALDI-TOF detected residual M-proteins in treated patients not detected by the other methods. Conclusion: This preliminary study demonstrates that MALDI-TOF MS method can provide detection, quantitation and isotyping data suitable for monitoring patients. This is a significant finding since the MALDI-TOF method is amendable to automation, is rapid and in its current format is cost-competitive with current clinical assays. Disclosures Murray: Mayo Clinic: Patents & Royalties: Patent Application Filed. Mills:Mayo Clinci: Patents & Royalties: Patent Application Filed. Barnidge:Mayo Clinic: Patents & Royalties: Patent Application Filed.

Abstract Abstract 2850 Myelofibrosis (MF), both primary myelofibrosis (PMF) and post essential thrombocytosis/polycythemia vera myelofibrosis (post ET/PV-MF), are chronic myeloproliferative neoplasms characterized by a progressive clinical course that leads to shortened survival. The heterogeneous nature of MF lends itself to a variable clinical course that commonly includes hepatosplenomegaly, constitutional symptoms, and progressive cytopenias. Medical therapy for myelofibrosis has been effective in palliation of common symptoms related to anemia, splenomegaly but allogeneic stem cell transplantation (ASCT) remains the only potentially curative therapeutic modality. The timing of ASCT, choice of conditioning regimen, patient selection and the impact of co-morbidities are critical to optimal use of this modality. We have retrospectively analyzed our experience for patients undergoing ASCT for primary and post ET/PV myelofibrosis at Mayo Clinic across all 3 sites: Scottsdale Arizona; Rochester, Minnesota; and Jacksonville, Florida. Methods: We conducted a retrospective review of all patients from 1992 to 2012 with PMF or post ET/PV-MF who underwent an ASCT at Mayo Clinic. This retrospective review included a waiver of informed consent and was approved by the Mayo Clinic Institutional Review Board. Patients that transformed to the MPN blast phase and individuals who underwent a second transplant for either relapse or graft failure were also included. Overall survival was estimated using Kaplan-Meier. Associations between prognostic factors and overall survival were assessed using Cox regression. Results: Baseline Patient Characteristics: Forty-eight patients (29 male) with a median age of 57 yrs (range 31–73) underwent ASCT. DIPSS-plus risk score was low in 2, intermediate 1 in 2, intermediate 2 in 9 and high in 35 patients. Disease type was PMF in 24, PV-MF in 10, ET-MF in 10, and MPN/MDS overlap in 4 pts. Eight patients evolved to the MPN-blast phase prior to transplant. JAK-2 mutation was positive in 27 patients and negative in 12 patients with JAK-2 status unknown in 9 patients. The median time from PV/ET to MF was 136 months (83–189 months) and from MF diagnosis to transplant was 59 months (3–144 months). All but 2 patients were red cell transfusion dependent prior to transplant (96%). Eight patients underwent splenectomy prior to transplant. Transplantation Characteristics: Patients who underwent ASCT received either myeloablative (MA, 13 pts) or reduced-intensity conditioning (RIC, 35 pts) regimen. The graft was from an unrelated donor in 22 pts and related donor in 26 pts with 44 being matched and 4 being mismatched. The myeloablative regimens included Bu/Cy, TBI/Cy, and Bu/Flu. The RIC regimens included flu/mel, Bu/Flu, FBM, and TBI/Flu. GVHD prophylaxis was with tacrolimus/MTX, CSA/MTX, and tacrolimus/MMF. Nineteen patients received ATG. Infectious disease prophylaxis, CMV monitoring, and additional supportive care measures were according to institutional guidelines. A majority of patients received peripheral blood stem cells with only 1 patient receiving bone marrow as the source of stem cells. Outcomes: The median time to neutrophil engraftment was 17.2 days. Two patients received a second transplant for relapsed disease. The incidence of graft failure was 10%. Graft versus host disease both acute and chronic occurred in 33 patients and 15 patients respectively. Day 100 overall survival was 92% and 2 year survival was 62% (95% CI 45–75%). There were no statistically significant associations between individual prognostic factors (DIPSS-plus classification, age, and HLA match) and survival. Conclusions: The Mayo Clinic national experience of ASCT for MF across our geographically diverse Cancer Center is encouraging. Our centers have transplanted 48 patients over the past 10 years with very favorable outcomes. Our results from a multi center practice are consistent with regards to survival, graft versus host disease, and types of transplants being performed compared to currently available published data from large single location transplant centers. This data helps confirm the prevailing knowledge that ASCT is a useful treatment. Disclosures: Mesa: Incyte: Research Funding; Lilly: Research Funding; Sanofi: Research Funding; NS Pharma: Research Funding; YM Bioscience: Research Funding.