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Abstract Histiocytic neoplasms are clonal, hematopoietic disorders characterized by an accumulation of abnormal monocyte-derived dendritic cells or macrophages in Langerhans Cell (LCH) and non-Langerhans (non-LCH) histiocytoses, respectively. The discovery of the BRAF V600E mutation in ~50% of patients with LCH and the non-LCH Erdheim-Chester Disease (ECD) provided the first molecular target in these patients and novel insights into the pathogenesis of these disorders. However, recurrent mutations in the majority of the ~50% of BRAF V600E-wild type patients with non-LCH are unknown. Moreover, recurrent mutations outside of the MAP kinase pathway are undefined throughout histiocytic neoplasms. To address these issues, we performed whole exome sequencing (WES) of frozen biopsies from 24 patients with LCH (n=10) or ECD (n=14) paired with peripheral blood mononuclear cells. 13/24 patients also underwent RNA sequencing (RNA-seq). All mutations in activating kinases were validated by droplet-digital PCR, while targeted-capture next-generation sequencing validated all others. Both adult (n=18; n=2 with LCH) and pediatric cases (n=9; n=8 with LCH) were included. Using combined WES/RNA-seq, activating kinase alterations were identified in 100% of patients. In LCH, 60% and 40% had BRAF V600E and MAP2K1 mutations, respectively. In non-LCH 51%, 14%, 14%, and 7% were BRAFV600E, ARAF, MAP2K1, and NRAS mutant (Fig1A). Overall, a mean of 7 non-synonymous mutations per adult patient was identified (range 1-22) compared with 5 mutations per pediatric patient (range 4-9; p =ns). Mutations affecting diverse cellular processes were found to co-exist with kinase mutations including mutations in epigenetic modifiers and the p38/MAPK pathway. In addition to kinase point mutations, RNA-seq identified recurrent, in-frame kinase fusions-a first for these disorders. All identified fusions were validated using FISH and RT-PCR. This includes novel fusions in BRAF (RNF11-BRAF and CLIP2-BRAF), as well as therapeutically important fusions in ALK (2 separate KIF5B-ALK fusions) and NTRK1 (LMNA-NTRK1;Fig1B). Expression of each fusion in Ba/F3 cells conferred cytokine-independent growth. Importantly, the BRAF fusions were found to be sensitive to MEK inhibition but resistant to vemurafenib while the ALK fusions conferred sensitivity to the ALK inhibitors crizotinib or alectinib. We next interrogated a validation cohort of 37 BRAF V600E-wild type, non-LCH, formalin-fixed, paraffin-embedded tissue samples using targeted mutational profiling for MAP2K1, ARAF, NRAS, KRAS, and PIK3CA. This revealed activating mutations in MAP2K1 (32%; n=12), NRAS (16%; n=6), KRAS (11%; n=4), PIK3CA (8%; n=3), and ARAF (3%; n=1). Three of the investigated non-LCH patients with refractory disease and progressive organ dysfunction were treated with targeted therapies based on the discovery of novel kinase alterations described above. Treatment of 2 refractory MAP2K1- mutant, non-LCH patients with MEK inhibitors (trametinib or cobimetinib) resulted in dramatic clinical improvement (Fig1C). Both patients have been maintained on MEK inhibitor single-agent therapy with a sustained clinical response for >100 days. Further evidence of effective targeted inhibition was found in a refractory ECD patient carrying an ARAF S214A mutation. This patient failed to respond to 3 lines of prior therapies and suffered near blindness due to disease infiltration in the retina and optic nerves. Given a recent report of complete response to sorafenib in a lung cancer patient with an ARAF S214C mutation, we initiated sorafenib. Within 12 weeks, there was improvement in the patientÕs eyesight and decreased infiltrative disease, coinciding with >50% decrease in mutant ARAF DNA in plasma cell-free DNA. Whole exome and transcriptome sequencing identified activating kinase mutations or translocations in all patients with the common downstream effect of activating the MAPK pathway. The preliminary, dramatic, clinical efficacy observed with use of MEK and RAF inhibitors in MAP2K1 - and ARAF-mutated, non-LCH patients further supports the central role of targeting the MAPK pathway in these tumors. The discovery of the discussed mutations and fusions in diverse kinases provides critical new insights into the genetic events central to a spectrum of adult and pediatric histiocytic neoplasms. Figure 1. Figure 1. Disclosures Off Label Use: This abstract describes use of MEK inhibitors (both tremetinib and cobimetinib) as well as sorafenib for MEK1 and ARAF mutant histiocytosis. . Stephens:Foundation Medicine, Inc.: Employment, Equity Ownership. Miller:Foundation Medicine, Inc.: Employment, Equity Ownership. Ross:Foundation Medicine Inc.: Employment. Ali:Foundation Medicine Inc.: Employment. Hyman:Chugai Pharma: Consultancy; Biotherapeutics: Consultancy; Atara: Consultancy, Honoraria.

Abstract Abstract 1825 Poster Board I-851 Purpose Recent advances in understanding of the molecular alterations that occur at the genetic and epigenetic levels in Multiple Myeloma (MM) have led to major leaps in identifying molecular pathways that regulate progression and resistance to therapeutic agents. However, despite great scientific advances at the genomic level, studies to identify signaling pathways deregulated at the functional proteomic level in MM are limited. We have previously demonstrated that Citron Rho Interacting Kinase (CRIK) is overexpressed in primary multiple myeloma (MM) cells, as compared to the normal plasma cell counterpart, using an antibody-based protein microarray technique. We therefore sought to investigate the functional role of CRIK in MM cells. Methods We determined the protein expression level of 512 polypeptides in 12 samples of newly diagnosed patients with MM using high-throughput proteomic analysis with antibody-based protein microarray. Primary CD138+ sorted MM cells were obtained from the bone marrow of patients after informed consent. MM.1S, RPMI8226, and INA6 MM cell lines were used in this study. Protein expression has been studied by immunoblotting. Gene expression analysis has been assessed using the Affymetrix U133A platform. Lentivirus was used to knockdown CRIK in MM cell lines (MM.1S, RPMI8226, INA6). DNA synthesis, cell survival, cell cycle profiling and apoptosis were assessed by thymidine uptake, MTT, PI and Annexin/PI staining and flow cytometric analysis, respectively. Results Overexpression of CRIK has been confirmed in primary CD138+ tumor cells isolated from bone marrow of 12 patients with MM, as compared to normal plasma cells obtained from healthy donors. We found that CRIK-knockdown exerted an anti-proliferative and pro-apoptotic effect only in IL-6-dependent MM cell line INA6; in contrast, no effect on proliferation and survival was observed in MM1.S and RPMI8226. Indeed, INA6 CRIK-knockdown cells were characterized by a reduction in the proliferation rate, associated with decreased S-phase and G2/M phase cell cycle arrest. Moreover, induction of cytotoxicity was also demonstrated in CRIK knockdown cells compared to scramble probe transfected or non-transfected cells. We also showed that CRIK knockdown led to cytokinesis in INA6, indicating a possible mechanism for inhibition of proliferation of these cells. We next correlated CRIK gene expression level (CIT) with prognosis using previously published gene expression datasets and found that CRIK correlated with poor prognosis. Conclusion In this study, we show that MM cells express a high level of CRIK, and that inhibition of this protein leads to significant inhibition of proliferation and survival of IL-6 dependent MM cells. Moreover, CRIK protein expression correlated with poor survival in patients with MM. Disclosures Anderson: Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Millennium: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Ghobrial:Millennium: Honoraria, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau.

Background: Distal femoral replacement (DFR) is a salvage option for complex primary and revision total knee arthroplasty (TKA). Although excellent immediate fixation and weight-bearing are achieved, there is a paucity of data on long-term outcomes of TKA with DFR. The purpose of the present study was to determine implant survivorship, clinical outcomes, and radiographic results of TKAs with contemporary DFR components in a large series. Methods: We identified 144 consecutive TKAs performed with DFR for non-oncologic indications from 2000 to 2015 at a single academic institution. Indications for the index DFR included 66 (46%) for native (n = 11) or periprosthetic (n = 55) femoral fracture, 40 (28%) for staged treatment of periprosthetic joint infection, 28 (19%) for aseptic TKA loosening, and 10 (7%) for other indications. Porous metal cones were used to augment femoral fixation in 28 patients (19%) and tibial fixation in 38 patients (26%). Outcomes included cumulative incidence of revision and reoperation (utilizing a competing risk model), Knee Society scores, and radiographic results. The mean age at the time of index DFR was 72 years, and 65% of patients were female. The mean follow-up was 5 years (range, 2 to 13 years) for the 111 patients who did not undergo revision, had not died, and were not lost to follow-up. Results: The 10-year cumulative incidences of revision for aseptic loosening, all-cause revision, and any reoperation were 17.0%, 27.5%, and 46.3%, respectively. There was an increased risk of reoperation in patients who underwent index DFR for aseptic TKA loosening (hazard ratio [HR], 2.30; p = 0.026) or periprosthetic joint infection (HR, 2.18; p = 0.022) compared with periprosthetic or native femoral fractures. However, there was no difference in risk of revision for aseptic loosening or all-cause revision based on the original operative indication. The mean Knee Society score increased from 45 preoperatively to 71 at the time of the latest follow-up (p < 0.001). Radiographic loosening was observed in 8 unrevised DFRs (7%). There were 7 above-the-knee amputations performed at the time of the final follow-up, all for intractable periprosthetic joint infection. Conclusions: TKAs with contemporary DFR had high 10-year cumulative incidences of both revision and reoperation, underscoring the salvage nature of this procedure as a final reconstructive option. Most patients experienced substantial clinical improvements with this end-stage revision procedure. Level of Evidence: Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Background: There is no consensus on managing severe patellar bone loss after total knee arthroplasty. We previously described an initial series involving a novel technique of patellar bone-grafting with a short follow-up. The purpose of this study was to determine long-term survivorship and the radiographic and clinical results of patellar bone-grafting during revision total knee arthroplasty in a larger series with an extended follow-up. Methods: We identified 90 patients from a single institution who underwent 93 patellar bone-grafting procedures for severe patellar bone loss from 1997 to 2014. The mean age of the patients was 70 years, and 46% of patients were female. Forty-five knees (48%) underwent first-time revisions, and 19 knees (20%) had undergone a failed attempt at patellar resurfacings. Intraoperative patellar caliper thickness increased from a mean of 7 to 25 mm after patellar bone-grafting (p < 0.01). Radiographic review determined changes in patellar height, tracking, and remodeling. Knee Society scores (KSSs) were calculated. The mean follow-up was 8 years (range, 2 to 18 years). Kaplan-Meier methods determined survivorship free of any revision and any reoperation. Cox proportional hazards analysis determined predictive factors for failure. Results: Survivorship free of patellar revision was 96% at 10 years. Survivorship free of any revision was 84% at 10 years. Survivorship free of any reoperation was 78% at 10 years. Increasing patient age was the only protective factor against further patellar revision (hazard ratio, 0.95; p < 0.01). When comparing initial radiographs with final radiographs, patellar height decreased from 22 to 19 mm (p < 0.01), 80% compared with 59% of patellae articulated centrally in the trochlea (p = 0.01), and 32% compared with 77% had remodeling over the lateral femoral condyle (p < 0.01). Anterior knee pain decreased from 51% to 27% postoperatively (p = 0.01). The mean knee flexion improved from 101° to 108° (p = 0.03). The mean KSS improved from 50 to 85 points (p < 0.01). Conclusions: Reliable long-term clinical results can be expected with patellar bone-grafting for severe patellar bone loss during revision total knee arthroplasty. Pain, range of motion, and other reported outcomes improve despite radiographic changes to patellar height, tracking, and remodeling. This technique is a durable and reliable option when standard patellar resurfacing is not possible. Level of Evidence: Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Abstract Objectives: Infection with the causative agent of visceral leishmaniasis (VL) may be either symptomatic or asymptomatic. In this study we aimed at investigating the prevalence of asymptomatic infections of leishmania in non-endemic villages in Gedaref state, Sudan. A descriptive cross-sectional study conducted during September and October 2014. Blood samples were collected for serological and molecular analysis. Sticky-traps, knockdown spray and CDC-miniature light traps were used for the collection of sandflies. Results: Ninety-Five participants were included; 52 from Abukishma, 15 Algadamblia Tirfa, 25 Abualnaja and 3 were from Algadamblia Aljabal . Females constituted 56 (58.9%) of the study participants while males were 39 (41.1%). The most frequent age group was >40-years (54.7%). Balanites/Acacia trees were the most planted tree inside the houses; 78 (82.1%). Also, 85 (89.5%) of the participants breed animals inside the house. DAT test revealed 5 positive participants (5.2%). 4/5 DAT positive were past VL infection. PCR detected 35 (36.8%) positive participants. A total of 31/35 was considered asymptomatic infections based on PCR. Households planted Balanites/Acacia trees or breed domestic animals were found in high percentages with L. donovani PCR positive participants (60.1%, 91.4%). No statistically significant was found for VL associated risk factors and VL asymptomatic participants.

Abstract Objectives: Infection with the causative agent of visceral leishmaniasis (VL) may be either symptomatic or asymptomatic. In this study we aimed at investigating the prevalence of asymptomatic infections of leishmania in non-endemic villages in Gedaref state, Sudan. A descriptive cross-sectional study conducted during September and October 2014. Blood samples were collected for serological and molecular analysis. Sticky-traps, knockdown spray and CDC-miniature light traps were used for the collection of sandflies. Results: Ninety-Five participants were included; 52 from Abukishma, 15 Algadamblia Tirfa, 25 Abualnaja and 3 were from Algadamblia Aljabal . Females constituted 56 (58.9%) of the study participants while males were 39 (41.1%). The most frequent age group was >40-years (54.7%). Balanites/Acacia trees were the most planted tree inside the houses; 78 (82.1%). Also, 85 (89.5%) of the participants breed animals inside the house. DAT test revealed 5 positive participants (5.2%). 4/5 DAT positive were past VL infection. PCR detected 35 (36.8%) positive participants. A total of 31/35 was considered asymptomatic infections based on PCR. Households planted Balanites/Acacia trees or breed domestic animals were found in high percentages with L. donovani PCR positive participants (60.1%, 91.4%). No statistically significant was found for VL associated risk factors and VL asymptomatic participants.

Background: Osteonecrosis of the hip is the underlying etiology for 3% to 12% of total hip arthroplasties (THAs). Compared with patients who undergo THA because of osteoarthritis, those who do so because of osteonecrosis typically are younger, have a greater number of underlying diagnoses, and have inferior clinical outcomes and implant survivorship. The purpose of this study was to compare the long-term implant survivorship (median follow-up, 10 years), functional outcomes, and radiographic results of contemporary THAs with a highly cross-linked polyethylene (HXLPE) liner between patients with osteonecrosis and those with osteoarthritis. Methods: All patients who underwent primary THA with an HXLPE liner from 1999 to 2007 were identified from our institutional total joint registry. Patients with a primary diagnosis of osteonecrosis were matched 1:1, on the basis of age, sex, and body mass index (BMI), to patients with a diagnosis of osteoarthritis. This resulted in 461 hips in 413 patients with osteonecrosis matched to 461 hips in 427 patients with osteoarthritis (mean age, 59 years; 47% female; and mean BMI, 29 kg/m 2 ). Long-term implant survivorship, patient-reported outcomes, and radiographic findings were compared. In addition, a subgroup analysis of the osteonecrosis group was performed to see whether certain underlying etiologies portended poor outcomes. The median follow-up was 10 years. Results: The 15-year cumulative rates of revision were 6.6% and 4.5% in the osteonecrosis and osteoarthritis groups, respectively (hazard ratio [HR] = 1.8, p = 0.09). The 15-year cumulative rates of any reoperation were 10.5% and 6.4% in the osteonecrosis and osteoarthritis groups, respectively (HR = 2.2, p = 0.008). There were no radiographic signs of component loosening or osteolysis in the entire cohort. Despite a lower median preoperative Harris hip score (HHS) for patients with osteonecrosis, both groups had marked improvements in their scores, which were similar at all time points after surgery. The cumulative rate of reoperations at 15 years was 0% for hips with radiation-induced osteonecrosis, 6.3% for those with alcohol-induced osteonecrosis, 9.0% for those with posttraumatic osteonecrosis, 12.1% for those with steroid-induced osteonecrosis, and 25% for those with idiopathic osteonecrosis. Conclusions: Contemporary THA with an HXLPE liner offers excellent long-term implant survivorship and functional outcomes for patients with osteonecrosis; however, the risk of a reoperation is higher when compared with patients with osteoarthritis. Level of Evidence: Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

AbstractFor patients who qualify, simultaneous bilateral total knee arthroplasty (TKA) is a viable option for the treatment of bilateral symptoms. However, the incidence of chronic obstructive pulmonary disease (COPD) has been steadily rising over the past few decades and may impact those who qualify as candidates for bilateral TKA. As such, the aim of this study was to determine the impact of COPD on postoperative outcomes in patients who receive simultaneous bilateral TKA. A retrospective cohort study was conducted utilizing data provided through the American College of Surgeons National Surgical Quality Improvement Program. All patients who had undergone simultaneous bilateral TKA between 2007 and 2016 were identified and further stratified into groups based upon the COPD status. Incidence of adverse events after TKA in the acute postoperative period was evaluated with univariate and multivariate analyses. COPD was found to be an independent risk factor for the development of major (odds ratio [OR]: 2.5; p = 0.015), renal (OR: 5.1; p = 0.02), and thromboembolic complications (OR: 2.5; p = 0.027). In addition, patients with COPD were at increased risk for having an extended hospital length of stay (LOS; p < 0.001) and development of urinary tract infections (p < 0.001). Patients with COPD are at higher risk for development of overall major complications, as well as renal and thromboembolic complications after simultaneous bilateral TKA. Interestingly, patients were not at increased risk for the development of pulmonary or wound complications. When considering a staged versus simultaneous bilateral TKA, surgeons should be aware of the impact COPD status has on the postoperative complication rate.

The in vitro activities of rifampin, rifabutin, rifapentine, and rifaximin were tested against 200 periprosthetic joint infection (PJI)-associated staphylococci. Seven rifampin-resistant isolates had MICs of ≥4 μg/ml. Three isolates had rifampin MICs of 0.25 to 1 μg/ml and harbored an Asp471Gly RpoB variant, suggesting that the CLSI rifampin-susceptible staphylococcal breakpoint of ≤1 μg/ml may be too high.