Parikh, Sameer A.

Abstract Background: CLL patients (pts) treated with novel targeted therapies continue to experience disease progression. Approximately 7-15% of relapsed CLL treated with ibrutinib or venetoclax developed Richter's syndrome (RS), an aggressive high grade lymphoma transformation. Standard chemotherapy has limited efficacy in RS. We hypothesized that checkpoint blockade would re-establish anti-tumor immune response in progressive CLL/RS and here we aim to update the clinical data and correlative analysis of MC1485: a phase 2 study of PD-1 blocking antibody pembrolizumab in relapsed/refractory CLL and RS. Methods: Relapsed/refractory CLL including RS enrolled in the CLL arm of MC1485 trial was reported here. The primary end point of this study is overall response rate (ORR). Pts with prior allogeneic stem cell transplant were excluded. Pembrolizumab 200 mg was administered intravenously every 3 weeks. NCI CTCAE v4.0 and IWCLL 2008 criteria were used for non-hematological adverse events (AE) and for CLL grade hematological AE. Tumor expression of PD-1 and PD-L1 were assessed with standard immunohistochemical (IHC) staining. Percentage expressions of individual antigens were analyzed with whole-slide scanning followed by image analysis with Image-Pro software (Media Cybernetics). Fluorescence in situ hybridization (FISH) was performed on available CLL/RS tissue sections to assess copy number of chromosome 9p region that contains PD-L1 and PD-L2. Results: 25 pts including 16 CLL and 9 RS (biopsy-proven large cell lymphoma) were enrolled in CLL arm. The median age was 69 years (46-81). Twelve (48%) pts had del(17p) or monosomy 17 or TP53 mutation. The median number of prior therapies was 4 (1-10). 96%, 72% or 48% of pts had received alkylator and anti-CD20 antibody, purine analog or anthracycline. Fifteen (60%) pts had prior ibrutinib and 12 (48%) progressed clinically while receiving ibrutinib, including 6 who progressed to RS and 6 who developed progressive CLL. The median number of pembrolizumab doses that pts received was 3 (1 to 21), administered over a median treatment duration of 11 weeks (1 to 56). Drug-related AE occurred in 21 pts (88%) with the most common ones being neutropenia in 9 (37%), cough in 7 (29%) and dyspnea in 6 (25%) pts. Drug-related grade 3 or above AE occurred in 9 (38%) pts with most common ones being thrombocytopenia (5, 21%), dyspnea (2, 8%), and fatigue (2, 8%). The most common immune-related AE was liver enzyme elevation (12%, 8% G3) and was reversible with therapy interruption or steroid therapy. Based on investigator assessment using the Revised Response Criteria for Lymphomas and IWCLL 2008 criteria, one RS pt had complete response (CR, 4%), 3 RS had partial responses (PR, 12%). Among 9 RS pts, 1 CR (11%), 3 PR (33%), 3 SD (33%) and 2 PD (22%) were observed. Thus the ORR in RS was 44%. No CLL pts achieved a CR/PR, 3 had SD and 9 had progressive disease (PD). The ORR of all pts was 16%. Of the 4 RS who had CR/PR, responses occurred early after 2 cycles of therapy and median duration of therapy for CR/PR pts was 8.3 months with data cut-off by June 30th 2016 (Figure 1A). The causes for therapy discontinuation in RS were PD (3, 33%), alternate therapy (2, 22%), and thrombocytopenia due to increased marrow CLL (1, 11%). Increased marrow CLL was observed in 2 RS pts with PR to RS phase of disease assessed by PET, thus the protocol was amended to allow addition of idelalisib/ibrutinib to control the underlying marrow CLL. For RS pts who had a CR/PR or SD, variable nodal responses were observed (Figure 1B). In particular, 6 RS who had prior ibrutinib experienced CR or PR or SD with nodal responses. After a median follow-up of 10.2 (1.9 to 16.1) months, the median overall survival (OS) for all pts was 10.7 months (95% confidence interval [CI], 5.4 to not reached). The 6 month OS rate for RS and CLL pts were 73% and 59%, respectively. Biomarker assessment using IHC analysis on 10 pts with available tumor/nodal tissues (6 RS and 4 CLL) showed an increased expression of PD-L1 (p = 0.02) and a trend for an increased expression of PD-1 (p = 0.1) in the group of pts with CR/ PR versus pts in the group with no clinical response. One out of 10 tested showed polysomic for chromosome 9p. Conclusion: Pembrolizumab had an acceptable safety profile in CLL and RS patients. We confirmed that pembrolizumab has substantial therapeutic activity in RS. Single-agent pembrolizumab does not appear to have clear activity in CLL. Disclosures Ding: Merck: Research Funding. Parikh:Pharmacyclics: Honoraria, Research Funding. Shanafelt:GlaxoSmithKline: Research Funding; Genentech: Research Funding; Janssen: Research Funding; Pharmacyclics: Research Funding; Celgene: Research Funding; Cephalon: Research Funding; Hospira: Research Funding.

Abstract INTRODUCTION: Among patients (pts) with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), the indications for liver biopsy are not known. Additionally, the histopathologic findings of CLL infiltration in the liver along with its clinical implications have not been thoroughly described in the literature. METHODS: We identified all pts with a diagnosis of CLL/SLL from the CLL Clinical Database at Mayo Clinic, Rochester, MN who underwent a liver biopsy. We also cross referenced the Mayo Clinic Hematopathology Database for all pts who underwent a liver biopsy. The indications for biopsy, description of the pathologic findings in the liver biopsy, CLL therapy and outcomes were abstracted from the clinical records. Retrospective pathology review was performed on cases with CLL involvement in which slides were available for review. RESULTS: Fifty-two CLL/SLL pts who underwent a liver biopsy were identified. The indications for liver biopsy were as follows: liver lesion identified on radiographic imaging in 21 (41%) pts, abnormal liver function tests (LFTs) in 17 (33%) pts, hepatosplenomegaly in 11 (21%) pts, and unknown in 3 (6%) pts. Among all 52 pts, there was concern for Richter transformation at time of biopsy in 7 (13%) pts. Types of biopsy were as follows: percutaneous in 20 (39%) pts, intraoperative in 17 (33%) pts, transjugular in 3 (6%) pts, and unknown in 12 (23%) pts. CLL/SLL involvement was identified in 38/52 (73%) pts undergoing liver biopsy. Among these, the diagnosis of CLL/SLL was made on liver biopsy in 8 pts, and 7 pts had additional findings on their liver biopsy including metastatic colon cancer (n=3), hemochromatosis (n=2), steatohepatitis (n=1), and cirrhosis (n=1). Liver biopsy revealed Richter transformation in 4 (8%) pts (3 pts with diffuse large B cell lymphoma (DLBCL) and 1 patient with Hodgkin lymphoma), other malignancy in the absence of CLL in 7 (15%) pts (2 metastatic colorectal, 2 metastatic esophageal, 1 hepatocellular carcinoma, 1 metastatic lung, and 1 neuroendocrine), and 1 patient with steatohepatitis. Two (4%) pts had normal findings on liver biopsy. Among the 38 pts with liver involvement by CLL, 27 had slides available for retrospective pathology review. CLL involvement ranged from 2-100% of the liver parenchyma. Seven pts (26%) underwent excisional biopsies or resections and 20 (74%) underwent core biopsies. The portal tracts were the most common region of the liver involved (22/26 pts, 85%). Of these, 8/22 (36%) pts had extension into the lobules or sinusoids, as well. Of the 4 cases without portal involvement, 2 showed extensive involvement such that it effaced the liver parenchyma in the region of involvement. One patient (4%) had a predominantly sinusoidal involvement. One patient (4%) showed small nodular infiltrates that were difficult to localize due to their size. Proliferation centers were noted in only 3 pts (11%). Most pts (29/38; 76%) whose liver biopsy demonstrated involvement by CLL did not receive immediate CLL-specific treatment. Nine of the 38 pts (24%) with CLL involvement on liver biopsy received therapy (Table): purine analog based therapy (n=4), rituximab and steroids (n=2), steroids only (n=1), alkylator and rituximab (n=1), and ibrutinib (n=1). Pts with extensive involvement of the liver by CLL were more likely to receive purine nucleoside analog based therapy compared to pts with portal infiltration by CLL (2/2 pts [100%] vs. 1/6 pts [17%]). The remaining pts were offered no therapy due to incidental finding of CLL in the liver biopsy (n=11), chemotherapy for other cancer (n=5), palliative care (n=3), or unknown (n=10). Pts with Richter's transformation received R-CHOP (n=2) and CHOP (n=1) for DLBCL, and ABVD (n=1) for Hodgkin lymphoma. Pts with other cancers without CLL received appropriate therapy for their underlying malignancy. CONCLUSION: Abnormal LFTs and radiographic abnormalities were the most common indications for a biopsy in this large cohort of CLL pts. Infiltration of the portal tracts by CLL/SLL was the most common histopathological finding. Proliferation centers were not commonly seen, which may make the diagnosis challenging for the pathologist if there is not a prior history of CLL/SLL. The mere presence of CLL/SLL infiltration did not mandate treatment and many pts were able to continue observation. Table Table. Disclosures Ding: Merck: Research Funding. Kenderian:Novartis: Patents & Royalties, Research Funding. Shanafelt:GlaxoSmithkKine: Research Funding; Celgene: Research Funding; Cephalon: Research Funding; Genentech: Research Funding; Janssen: Research Funding; Pharmacyclics: Research Funding; Hospira: Research Funding. Parikh:Pharmacyclics: Honoraria, Research Funding.

Abstract Background: Individuals with clinically ascertained monoclonal B-cell lymphocytosis (c-MBL) having the phenotype of the chronic lymphocytic leukemia (CLL) have a 1-4% per year risk of progression to CLL requiring therapy. The risk factors for progression and the outcomes of individuals with c-MBL are not well defined. Methods: Using the Mayo Clinic CLL Database, we identified individuals with c-MBL (absolute B-cell count of <5x109/L, in the absence of symptoms, organomegaly, splenomegaly and cytopenias) who were seen at Mayo Clinic, Rochester, MN between 01/1995 - 5/2016. Patients in whom an absolute B-cell count was not available were included in the analysis if the absolute lymphocyte count was <5x109/L. Baseline clinical characteristics and prognostic test results (including IGHV mutation status, genetic abnormalities detected by FISH, and expression of ZAP-70, CD38 and CD49d) were recorded. Time to first therapy (TFT) was analyzed using cumulative incidence methods accounting for competing risk of death. Multivariable Cox proportional hazards regression analysis was used to identify factors that predicted TFT. Because of missing data for some prognostic parameters, multiple models were run, introducing one novel prognostic factor at a time to the base model (which consisted of age and sex). Overall survival (OS) of these individuals was compared to age- and sex-matched population of the state of Minnesota. Results: Eight hundred and fifty-one individuals with c-MBL were identified and included in this analysis. Median age was 69 years (range, 38-95 years), and 527 (62%) were males. The median absolute B-cell count at the time of diagnosis was 2.6 x 109/L (range, 0.1-5.0 x 109/L). The median serum beta-2 microglobulin (β2M) was 2.2 mg/dL (range, 1.0 - 21.5 mg/dL). One hundred and nine (30%) individuals had unmutated IGHV genes, and 38 (7%) had high-risk FISH (defined as either del17p13 or del11q23). The CD38 (≥30%), ZAP-70 (≥20%), and CD49d (≥30%) status was positive in 19%, 23% and 34% individuals, respectively. After a median follow-up of 6.8 years, 99 individuals required therapy for progressive disease (at a rate of 2.1% per year, Figure 1). On multivariable analysis, the following factors were associated with a higher risk of progression to CLL requiring therapy: a) unmutated IGHV status (hazard ratio [HR]:3.8, 95%CI 2.1 - 7.0, p<0.0001); b) positive CD49d status (HR: 3.1, 95%CI 1.6 - 5.9, p=0.0006); and c) positive CD38 status (HR: 2.8, 95% CI 1.7 - 4.8, p<0.0001). Although the HR for high-risk FISH was 2.0 (95% CI 0.9 - 4.4), it was not significantly associated with TFT (p=0.11), likely due to small sample size. Age, sex, serum β2M, and ZAP-70 expression were not predictive of TFT. Among these individuals with B-cell counts <5x109/L, further stratification of the absolute B-cell count at diagnosis showed no association with TFT (Figure 2). The median OS of individuals with c-MBL was 11.8 years. Although the OS among individuals with c-MBL and the age- and sex-matched general population of Minnesota appeared similar for the first 10 years of follow-up, OS was significantly shorter in the c-MBL group during the full follow-up interval (p=0.004, Figure 3). Conclusion: In this large cohort of individuals with clinically ascertained MBL, the risk of progression to CLL requiring therapy was 2.1% per year. Biological characteristics of the B-cell clone including IGHV mutation status, and CD49d and CD38 status predicted time to first CLL therapy. On extended follow-up, the OS of individuals with c-MBL was significantly shorter relative to age- and sex-matched general population. These findings have important implications for counselling individuals with clinically ascertained MBL. Disclosures Parikh: Pharmacyclics: Honoraria, Research Funding. Ding:Merck: Research Funding. Kenderian:Novartis: Patents & Royalties, Research Funding. Shanafelt:Pharmacyclics: Research Funding; GlaxoSmithkKine: Research Funding; Janssen: Research Funding; Genentech: Research Funding; Celgene: Research Funding; Cephalon: Research Funding; Hospira: Research Funding.

Abstract Abstract 2901 Background: The median age at diagnosis of patients (pts) with chronic lymphocytic leukemia (CLL) is 72 years (yrs). According to the Surveillance and Epidemiology End Results (SEER) database, approximately 11% of all pts diagnosed with CLL in 2009 were <55 yrs. All previously reported series on the natural history of younger CLL pts are more than a decade old, and did not include information on contemporary prognostic parameters (such as immunoglobulin heavy chain gene mutation status [IGHV], genetic abnormalities by fluorescence in-situ hybridization [FISH], ZAP-70, etc). These reports also occurred prior to the introduction of modern treatment strategies (e.g. chemoimmunotherapy (CIT); reduced intensity allogenic stem cell transplant [SCT]), making their data on important clinical outcomes such as time to first treatment (TTT) and overall survival (OS) of uncertain relevance to younger pts in the modern era. Methods: We explored the natural history of younger pts with CLL using the Mayo Clinic Database. All pts ≤ 55 with pathologic diagnosis of CLL who were seen at the Mayo Clinic between January 1995 and April 2012 were included in this study. Baseline demographic and clinical characteristics, prognostic variables and administered treatments were abstracted from the medical records. Outcomes of pts in this cohort was compared to CLL pts >55 seen during the same time period. OS of pts ≤55 was also compared to the age- and sex- matched normal population of the state of Minnesota. The Mayo Clinic Institutional Review Board approved this study. Results: Collectively, 844 pts ≤ 55 yrs (median age, 48.7 yrs) with newly diagnosed CLL and seen within 1 year of diagnosis were included in this analysis. The characteristics of these pts were compared to 2324 newly diagnosed pts>55 yrs (median age, 68.4 yrs) seen during the same interval. When compared to pts>55, younger pts were more likely to present as intermediate Rai stage disease (p<0.0001), IGHV unmutated (p=0.001), and ZAP-70 positive (p=0.009). Younger pts were also more likely to have 1 or more first degree relatives with CLL (familial CLL) than older pts (10.9% vs. 8.5%; p=0.04). No significant differences were seen in the gender distribution, CD38 status, or FISH risk category. When pts ≤ 55 were further stratified by age, 204 (24%) were ≤45 yrs, 272 (32%) were 46–50 yrs, and 368 (44%) age 51–55 yrs at diagnosis. Similar to the comparison with the >55 year old group, pts ≤45 were more likely to present with intermediate Rai stage disease (61.7%) than those 46–50 yrs (52.5%), or 51–55 yrs (48.8%; p<0.01). Pts ≤45 were also more likely to be IGHV unmutated (p=0.034) and ZAP-70 positive; however, the ZAP-70 status was not significantly different (p=0.095). No difference in the prevalence of familial CLL was observed by the age stratifications of the ≤55 group. After a median follow-up of 5.5 yrs (range, 0–17 yrs), 426 (50%) pts ≤55 had received treatment for CLL and 192 (23%) pts had died. Pts ≤55 had a shorter TTT (4.0 yrs vs. 5.2 yrs; p=0.001) but longer OS (12.5 yrs vs. 9.5 yrs; p<0.0001) compared to pts >55 yrs. In contrast, no differences in TTT or OS were observed when the age ≤55 pts were sub-stratified into the ≤45, 46–50, and 51–55 age groups. A significantly higher proportion of pts≤55 received SCT than those >55 (7% vs. 1%; p<0.0001), with even further stratification of the ≤55 group (SCT age≤45: 13.7%; age 46–50: 5.1%; age 51–55: 3.5%; p<0.0001). As a group, CLL pts ≤55 have significantly shorter OS than the age- and sex-matched population (median CLL=12.5 yrs; median population=not reached; p<0.0001, Figure). However, pts≤55 who were Rai Stage 0 and had mutated IGHV had comparable survival to the general population (p=0.97). Similarly, pts≤55 who were Rai Stage 0 and had favorable FISH results (13q- or normal) had comparable survival to the general population (p=0.27). Conclusion: Our study is the first comprehensive analysis of younger CLL pts in the modern era. We found that younger pts are more likely to present with intermediate Rai stage disease, and have IGHV unmutated and ZAP-70 positive status. Consistent with these characteristics, younger pts experience shorter TTT. Although the OS of younger CLL pts is longer than those >55, their survival relative to the age- and sex-matched normal population is profoundly shortened even with the advent of CIT and SCT. Disclosures: Shanafelt: Genentech: Research Funding; Glaxo-Smith-Kline: Research Funding; Cephalon: Research Funding; Hospira: Research Funding; Celgene: Research Funding; Polyphenon E International: Research Funding.

Abstract Introduction: The use of B-cell receptor (BCR) signal inhibitors-based therapies (e.g., Ibrutinib) for B-chronic lymphocytic leukemia (CLL) was initiated just a few years ago but has rapidly escalated due to their clinical efficacy and relative ease of use. However newer therapeutic approaches are needed due to multiple issues including the continued need to improve complete responses and reduce toxicity profiles. To that end our group has discovered a novel membrane target in the ubiquitous presence of Axl receptor tyrosine kinase (Axl RTK) on CLL B-cells and has reported that the Axl RTK inhibitor TP-0903 is able to induce apoptosis of CLL B-cells at nanomolar doses (Sinha, Clin Cancer Res, 2015). Given this we assessed if TP-0903 would be effective in the induction of apoptosis of leukemic B-cells from CLL patients who are currently on Ibrutinib therapy or whom have relapsed while on Ibrutinib treatment. Methods: Relapsed/refractory CLL patients (n=22) who were placed on Ibrutinib for progressive disease provided blood samples at a median of 3.2 months after Ibrutinib therapy initiation for these studies. We also obtained sequential samples on 8 patients from initial start of ibrutinib therapy and then over a 6 month follow-up period. CLL B-cells from these blood samples were subject to Ficoll separation, purified by using a Rosette Sep B-cell enrichment kit and then studied by flow cytometry to determine Axl RTK expression levels by flow cytometric analysis. Purified CLL B-cells (CD19+/CD5+) were cultured with TP-0903 in vitroat increasing doses (0.01µM - 0.50µM) for 24 hours and the LD50 dose was determined. In addition, 3 CLL patients who had been on Ibrutinib therapy and had a documented relapse were studied in similar fashion using TP-0903. LD50-sensitivity was measured. "LD50-sensitivity" was defined as an LD50 ≤0.50µM and "insensitive" was defined as an LD50 dose >0.50µM. CLL prognostic factors (e.g., FISH, IGHV mutation status, Rai stage, CD38, and CD49d) were evaluated at the time of ibrutinib treatment. Differences in factors between sensitive and insensitive cases were computed using the Kruskal-Wallis test for continuous variables and Chi-square test for categorical variables. Results: Twenty-two CLL patients (5 female, 17 male) were included in the analysis. Fourteen (64%) patients were found to be TP-0903 LD50-sensitive. Axl expression on CLL B-cells for this cohort was heterogeneous with a median of CD19+/CD5+ cells positive for Axl at 69.9% (range of 2.7-91.3%). The sensitive subjects tended to be younger with a median age at Ibrutinib treatment initiation of 62 vs 75.5 years (p=0.004). There were no significant differences in gender, FISH, IGHV mutation status, CD38, CD49d, or Rai stage between the sensitive and insensitive LD50 groups. There were no significant differences in relation to median Axl expression on CLL B-cells (sensitive: 72.6%, range: 2.7-91.3%; insensitive: 41.5%, range: 16.5-83.1%; p=0.35). The median number of treatments prior to initiation of ibrutinib did not differ between sensitivity groups (sensitive: 2.53, range: 8-10; insensitive: 43.5, range 12-20; p=0.2833). Association for ZAP70+ CLL B-cells tended to have more apoptosis induction by TP-0903 (sensitive: 84.6% ZAP70+; insensitive: 42.9% ZAP70+; p=0.052). In 8 CLL patients that were studied sequentially while on Ibrutinib continued to express Axl or increased their Axl expression (n=2) over a 3-6 month follow-up period. Three CLL patients who had relapsed on Ibrutinib were sensitive to TP-0903 with LD50 values of ≤0.50µM. Summary: Here we find that CLL B-cells from over 60% of relapsed CLL patients on Ibrutinib therapy were highly sensitive to the high-affinity Axl inhibitor TP-0903 with induction of apoptosis at nanomolar doses (≤0.50µM). The sensitivity of CLL B-cells to TP-0903 appears to be independent of Axl expression levels and of the known CLL prognostic factors but more evident for younger patients and for ZAP70+ expression status. Given this level of activity for apoptosis induction of CLL B-cells by TP-0903 encourages the further testing of this drug in clinical trials for CLL patients. Disclosures Parikh: Pharmacyclics: Honoraria, Research Funding. Shanafelt:Pharmacyclics: Research Funding; Janssen: Research Funding; Genentech: Research Funding; GlaxoSmithKline: Research Funding; Celgene: Research Funding; Cephalon: Research Funding; Hospira: Research Funding. Warner:Tolero Pharmaceuticals: Employment, Equity Ownership, Patents & Royalties. Bearss:Tolero Pharmaceuticals: Employment, Equity Ownership, Patents & Royalties. Kay:Pharmacyclics: Research Funding; Tolero Pharmaceuticals: Research Funding; Acerta: Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees; Morpho-Sys: Membership on an entity's Board of Directors or advisory committees; Infinity Pharm: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees.

Abstract BACKGROUND: Infiltration of the spleen plays an important role in the disease progression of patients with chronic lymphocytic leukemia (CLL). Despite this fact, the role for splenectomy in the management of CLL is not well defined. Historically, splenectomy has primarily been used for management of select patients with auto-immune cytopenias (e.g. autoimmune hemolytic anemia [AIHA], immune thrombocytopenic purpura [ITP]). We conducted a retrospective study to evaluate the utility of splenectomy in CLL patients cared for at Mayo Clinic over the last 20 years. METHODS: We used the Mayo Clinic database to identify all CLL patients who underwent splenectomy at Mayo Clinic since 1995. Medical records were reviewed to identify the indications for splenectomy, the pathologic findings at the time of surgery, and clinical outcomes. The indications for splenectomy were categorized as: diagnostic splenectomy, AIHA, ITP, symptomatic splenomegaly, and other. Pathology reports were reviewed to identify the findings at the time of surgery with respect to involvement by CLL and/or other lymphoproliferative disorders. RESULTS: Of the 5333 CLL patients seen at Mayo Clinic between 1/1/1995 and 12/31/2015, 107 (2%) underwent splenectomy at Mayo. The rate of splenectomy in female subjects was 1.7% (31/1779), and the rate in male subjects was 2.1% (76/3554). Of the 2354 subjects with IGHV mutation status, the rate of splenectomy in IGHV mutated subjects was 2.1% (23/1085) compared to 0.7% (9/1269) in IGHV unmutated subjects (p=0.004). The indication for splenectomy in these 107 patients was diagnostic splenectomy in 14 (13.1%) patients, ITP in 22 (20.6%), hemolytic anemia in 19 (17.8%), ITP and hemolytic anemia in 3 (2.8%), symptomatic splenomegaly in 46 (43.0%), and 3 (2.8%) other lymphomas. The rate of splenectomy decreased over the interval of the study (Figure). The per year risk of requiring splenectomy for patients diagnosed with CLL prior to 1995 was 0.32%/year, compared to 0.30%/year for those diagnosed from 1995-1999, 0.24%/year for those diagnosed from 2000-2004, 0.15%/year for those diagnosed from 2005-2009, and 0.16%/year for those diagnosed from 2010-2015 (p=0.01). The indication for splenectomy also changed over the study interval (Table) Pathologic review of the spleen demonstrated normal splenic tissue in 3 (2.8%), infiltration by CLL in 99 (92.5%), involvement by diffuse large B-cell lymphoma in 2 (1.9%) and involvement by other lymphomas in 3 (2.8%; T-cell lymphoma [n=1], T-cell large granular lymphocytic leukemia [n=1], and splenic marginal zone lymphoma [n=1]). CONCLUSION: These findings describe a large experience with the use of splenectomy in patients with CLL. Splenectomy is utilized relatively rarely (2% of CLL patients). The role of splenectomy in the management of CLL also appears to be changing with both a decreased frequency of splenectomy and a change in the indication for splenectomy over the last 2 decades. The potential benefits of splenectomy must be weighed against the know risks such as a lifelong increased risk of infection, as well as a higher risk of thromboembolism and secondary cancers. Splenectomy Indication by Time Period of CLL Diagnosis Table 1 Table 1. Figure 1 Figure 1. Disclosures Parikh: Pharmacyclics: Honoraria, Research Funding. Ding:Merck: Research Funding. Shanafelt:GlaxoSmithkKine: Research Funding; Janssen: Research Funding; Genentech: Research Funding; Pharmacyclics: Research Funding; Cephalon: Research Funding; Celgene: Research Funding; Hospira: Research Funding.

Abstract INTRODUCTION: The prevalence of liver dysfunction in patients with previously untreated chronic lymphocytic leukemia (CLL) is unknown; knowledge of which may provide important context for emerging therapeutic options with possible hepatotoxicity. The impact of liver dysfunction on outcomes of CLL patients is not well described. METHODS: Between 09/1993 and 04/2016, previously untreated CLL patients seen in the Division of Hematology at Mayo Clinic at diagnosis (<12 months) and who had baseline assessment of at least one of the following liver function tests (LFTs): alkaline phosphatase (ALP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), or total bilirubin were included in this analysis. Baseline lab values were defined as the closest value to CLL diagnosis for each lab within 12 months prior to diagnosis up through 6 months after CLL diagnosis. Patients with at least one abnormal LFT (defined as greater than 1.5 x the upper limit of normal) were classified as having liver dysfunction at diagnosis. Analysis for factors related to baseline liver function was performed using age- and sex-adjusted logistic regression models. Kaplan-Meier methods and multivariable Cox regression analysis was used to evaluate time to first treatment (TTFT) and overall survival (OS). RESULTS: Of 2336 previously untreated CLL patients who met the inclusion criteria, 123 (5%) patients had at least one abnormal LFT value at time of diagnosis. Thirty five patients had abnormal AST (median value 106 U/L, range 72-745 U/L, reference range 8-48 U/L), 25 patients had abnormal ALT (median 112 U/L, range 82-313 U/L, reference 7-55 U/L), and 54 patients had abnormal total bilirubin (median 2.10 mg/dL, range 1.8-26.5 mg/dL, reference range ≤ 1.2 mg/dL). Forty five patients had abnormal alkaline phosphatase; 35 patients in the year 2003 or later (median 198 U/L, range 172-2269 U/L, reference range 45-115 U/L) and 10 patients in 2002 or earlier (median 471.5 U/L, range 394-706 U/L, reference range 98-260 U/L). Abnormal LFTs were more common among those with advanced Rai stage disease (Rai 0-II=4.7% vs. Rai III-IV=13.4%; p<0.001) and among patients with lower hemoglobin (median 13.1 g/dL vs. 13.9 g/dL; p<0.001) at diagnosis. No difference in the rate of abnormal LFTs was observed based on cytogenetic abnormalities detected by FISH or CD38, CD49d, ZAP-70 or IGHV gene mutation status. There was no significant difference in prior alcohol abuse history between patients with liver dysfunction at diagnosis (6%) and those without (5%) (p=0.63). Similarly, there was no significant difference in body mass index between groups (median 27.8 vs. 27.8; p=0.12). After 12 years of follow-up, an estimated 69% of the cases with abnormal LFTs were treated. The most common type of treatments included anti-CD20 monoclonal antibody therapy only, followed by purine nucleoside based chemoimmunotherapy, and an alkylating agent with a monoclonal antibody. The median time to treatment was 4.3 years for cases with abnormal LFTs compared to 6.3 years for cases without abnormal LFTs (p=0.02). However, after adjusting for age, sex and Rai stage, there was no difference in TTFT among patients with abnormal LFTs at baseline compared to those with normal LFTs (hazard ratio [HR] = 1.2 (95% CI, 0.9-1.6); p=0.23). The median survival of CLL patients with abnormal LFTs at diagnosis was significantly shorter than those with normal LFTs (8.6 vs. 11.6 years, p<0.001, Figure 1). After adjusting for age, sex and Rai stage, multivariable cox regression analysis showed that abnormal LFTs retained independent prognostic significance for OS with a HR of 1.4 (95% CI, 1.1-1.8; p=0.012). CONCLUSION: At the time of CLL diagnosis, ~1 out of every 20 patients with previously untreated CLL has abnormal LFTs. These data provide context to the recent reports of hepatotoxicity with the use of signal inhibitors in untreated CLL. Although the presence of liver dysfunction at diagnosis does not seem to predict a shorter TTFT, the OS of these patients is significantly shorter compared to patients who have normal LFTs. Figure 1 Figure 1. Disclosures Ding: Merck: Research Funding. Kenderian:Novartis: Patents & Royalties, Research Funding. Kay:Pharmacyclics: Research Funding; Tolero Pharmaceuticals: Research Funding; Acerta: Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees; Morpho-Sys: Membership on an entity's Board of Directors or advisory committees; Infinity Pharm: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Shanafelt:Janssen: Research Funding; Pharmacyclics: Research Funding; GlaxoSmithkKine: Research Funding; Genentech: Research Funding; Cephalon: Research Funding; Celgene: Research Funding; Hospira: Research Funding. Parikh:Pharmacyclics: Honoraria, Research Funding.

Abstract BACKGROUND: The study of rare diseases is limited by the uncommon nature of the conditions as well as the widely dispersed patient populations. Current rare disease registries such as the National Organization of Rare Diseases utilize centralized platforms for data collection; however because of their broad nature, these do not always capture unique, disease specific elements. Hairy Cell Leukemia (HCL) is a rare leukemia globally with approximately 900 new cases diagnosed in the US each year. The HCL Foundation undertook creation of a Patient Data Registry that collects data from multiple HCL Centers of Excellence (COE) around the globe to better understand the complications, treatment outcomes, disease subtypes, comorbid conditions, epidemiology, and quality of life of patients with HCL. METHODS: Investigators at The Ohio State University Department of Biomedical Informatics and Division of Hematology in collaboration with the HCL Foundation developed a Patient Data Registry (PDR) for the longitudinal capture of high quality research data. This system differs from other registries in that it uses a federated( rather than centralized) architecture, wherein data is queried and integrated in an on-demand manner from local registry databases at each participating site. Further, the data collected for use in the registry combines both automated exports from existing electronic health records (EHRs) as well as additional data entered via a set of web-based forms. All manually entered data comes from source documents, and data provenance spanning electronic and manually entered data is maintained via multiple technical measures. Patients may be enrolled at HCL COE, or, if they do not have access to a COE they may enroll via a web-based portal (www.hairycellleukemia.org). At this time due to regulatory requirements the web-based portal is available to US patients only. All data are de-identified (see Figure 1: De-Identification Workflow) which reduces regulatory burden and increases opportunities for data access and re-use. End users have access to data via a project-specific query portal. RESULTS: The Patient Data Registry has been deployed at The Ohio State University, Royal Marsden Hospital, and MD Anderson Cancer Center, and is undergoing deployment at the University of Rochester. Up to 25 international HCL COE may participate. In addition, US patients are actively entering the registry via the web-based portal. To date, 227 patients have been consented to the registry with 119 of these being via the web-based entry point. CONCLUSION: We created an international and web-based patient data registry which will enable researchers to study outcomes in HCL in ways not previously possible given the rarity of the disease. This work was made possible by research funding from the Hairy Cell Leukemia Foundation. Figure De-Identification Workflow Figure. De-Identification Workflow Disclosures Andritsos: Hairy Cell Leukemia Foundation: Research Funding. Anghelina:Hairy Cell Leukemia Foundation: Research Funding. Lele:Hairy Cell Leukemia Foundation: Research Funding. Burger:Pharmacyclics: Research Funding. Delgado:Gilead: Consultancy, Honoraria; Novartis/GSK: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Roche: Consultancy, Honoraria, Research Funding; Infinity: Research Funding. Jones:AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics, LLC, an AbbVie Company: Membership on an entity's Board of Directors or advisory committees, Research Funding. Lozanski:Beckman Coulter: Research Funding; Genentech: Research Funding; Stemline Therapeutics Inc.: Research Funding; Boehringer Ingelheim: Research Funding. Montserrat:Morphosys: Other: Expert Testimony; Vivia Biotech: Equity Ownership; Gilead: Consultancy, Other: Expert Testimony; Pharmacyclics: Consultancy; Janssen: Honoraria, Other: travel, accommodations, expenses. Parikh:Pharmacyclics: Honoraria, Research Funding. Park:Genentech/Roche: Research Funding; Amgen: Consultancy; Juno Therapeutics: Consultancy, Research Funding. Robak:Pharmacyclics, LLC, an AbbVie Company: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding. Tam:janssen: Honoraria, Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees. Heckler:Hairy Cell Leukemia Foundation: Research Funding. Payne:Hairy Cell Leukemia Foundation: Research Funding.

Abstract Background Although hypogammaglobulinemia is a well-recognized complication in patients with chronic lymphocytic leukemia (CLL), its prevalence at the time of CLL diagnosis and association with novel prognostic markers and clinical outcomes are not well understood. Methods All patients seen at Mayo Clinic between 1/1995 - 4/2013 with newly diagnosed CLL (<12 months diagnosis) and who had baseline assessment of serum immunoglobulin G (IgG) were included in this analysis. Baseline demographic and clinical characteristics as well as serum IgG levels measured by either immunoassay or serum protein electrophoresis analysis were recorded. Based on the normal range for IgG at our laboratory, patients with serum IgG<757 mg/dL were classified as having hypogammaglobulinemia. Patients with IgG<757 were also further stratified by terciles (lower tercile: IgG<585 mg/dL; middle tercile: IgG 585-687 mg/dL, upper tercile: IgG 688-756 mg/dL). The relationship between hypogammaglobulinemia at diagnosis and prognostic parameters including immunoglobulin heavy chain (IGHV) gene mutation status, genetic abnormalities detected by fluorescence in-situ hybridization (FISH), and ZAP-70, CD38 and CD49d expression was assessed. Associations of hypogammaglobulinemia with time to first treatment (TTT) and overall survival (OS) was also evaluated. Results Of 1485 patients who met the eligibility criteria, 382 (26%) had hypogammaglobulinemia (median IgG=624 mg/dL) at the time of CLL diagnosis while the remaining 1103 (74%) had normal serum IgG levels (median IgG=1040 mg/dL). Baseline demographic and clinical characteristics of patients with and without hypogammaglobulinemia are shown in Table 1. When patients with hypogammaglobulinemia (IgG<757 mg/dL) were further stratified into terciles, patients in the lower tercile (n=127) were more likely to have advanced Rai stage (III-IV) at diagnosis (15% vs. 6% vs. 4%, p=0.008), be CD49d positive (56% vs. 43% vs. 32%, p=0.01), and have trisomy 12 on FISH testing (29% vs. 24% vs. 9%, p=0.005) compared to patients in the middle (n=127) and upper (n=128) terciles. After median follow-up of 4.2 years, 479 (32%) patients had received treatment for CLL, and 328 (22%) patients had died. The median TTT for patients with hypogammaglobulinemia was 3.8 years compared to 7.4 years for patients with a normal IgG (p-value<0.001). Among patients with hypogammaglobulinemia, the median TTT for patients in the lower, middle, and upper terciles were 1.7, 2.9, and 6.3 years respectively (p-value<0.001, Figure 1). On multivariable analysis that included age, gender, Rai stage, IGHV mutation status, FISH risk category and hypogammaglobulinemia, the following were independently associated with a shorter TTT: advanced (III-IV) Rai stage (hazard ratio [HR] =15.3, p<0.0001); intermediate (I-II) Rai stage (HR=3.0, p<0.0001); unmutated IGHV (HR=2.6, p=<0.0001); and hypogammaglobulinemia (HR=1.5, p=0.02). Conclusion In this large cohort study, approximately one-quarter of CLL patients had a low serum IgG level at the time of diagnosis. High-risk features, including advanced Rai stage and expression of CD49d, were associated with greater risk of hypogammaglobulinemia at the time of diagnosis. Patients with hypogammaglobulinemia at diagnosis had shorter TTT, a finding that persisted after adjusting for other prognostic factors. Evaluation of acquired hypogammaglobulinemia during the course of follow-up among patients who initially had normal IgG levels is ongoing. Disclosures: Shanafelt: Genentech: Research Funding; Glaxo-Smith-Kline: Research Funding; Cephalon: Research Funding; Hospira: Research Funding; Celgene: Research Funding; Polyphenon E International: Research Funding.

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.