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Abstract Background Multiple myeloma (MM) is uncommon in patients below 40 years of age. Between 1960 and 1992 when stem cell transplantation (SCT) was rarely performed and novel agents were unavailable, overall survival (OS) was reported to be 54 months in the Mayo Clinic series of patients with MM below forty years of age. The impact of novel agents or SCT in this population is unclear. Herein, we report the outcomes of patients under 40 years of age who were evaluated over a span of more than five decades with a focus on the periods contemporaneous with the introduction of SCT and novel agents, the major therapeutic milestones in the management of MM. Methods We analyzed the medical records of patients with MM under 40 years of age who were evaluated at Mayo Clinic, Rochester, MN between 1/1/1960 and 12/31/2011. SCT and novel agents were utilized infrequently prior to the years 1990 and 2000, respectively. Patients were therefore divided into three cohorts by the year of diagnosis of MM: Group A (1960 -1979), Group B (1980 to 1999) and Group C (2000 –2011) to assess the impact of major therapeutic advances (i.e. Increased utilization of SCT and novel agents compared to conventional chemotherapy). OS was calculated by the Kaplan -Meier method. Results Out of 8063 unique MM patients seen at our institution during this period, 174 (2%) patients were under 40 years of age at diagnosis. The median age at diagnosis was 36 years (range: 19-39). The estimated median follow-up of the entire cohort was 179 months (95% CI: 149-196 months). The median OS of the entire cohort was 76 months (95% CI: 45-80 months) from diagnosis. The median OS of patients in Groups A (n=29, 17%), B (n=93, 53%), and C (n=52, 30% ) was 44 months (95% CI: 20- 76), 79 months (95% CI: 46-97), and 92 months (95% CI: 42-NR), respectively (p=0.005). No significant OS difference was noted between Groups B and C (Figure). Sixty-six (38%) patients underwent at least one SCT (autologous: 56 patients and allogeneic 10 patients). The utilization of SCT increased over the three time periods from Group A 0%, Group B 39% and Group C 58% (p<0.001). Of 153 patients in whom front-line therapy-related data were available 118 (77%) received conventional and 35(23%) received novel agents. The median OS of patients who underwent transplantation (n=66) was 93 months compared to 46 months for those who did not (n=108, p=.01). In the 66 patients who underwent SCT, the median OS was 93 months for conventional agents-based induction (95% CI: 73-143) versus 97 months (95% CI: 41-187) for novel agent based induction (p=.4). Sixty-eight (40%) patients received novel agents at some point during the course of their disease [bortezomib 35 (54%), thalidomide 44 (67%), lenalidomide 47 (71%) and pomalidomide 7(11%)]. The median survival of these patients was 131 (95% CI: 88-161) months versus to 46 (CI: 37-74) months for those (n=106) receiving conventional agents only (p=0.0002). Conclusions OS of patients with MM under 40 years of age in the pre-transplant era (Group A) was significantly shorter than that of patients diagnosed in the era of SCT (Group B) and SCT plus novel agents (Group C). Although improvement of survival outcomes is evident with utilization of novel agents, similar outcomes of Groups B and C indicate lack of incremental benefit over SCT with utilization of novel agents. Maximal survival gain coincides with the introduction of SCT in this unique patient cohort. Disclosures: Kumar: Celgene: Consultancy, Research Funding; Millennium: Consultancy, Research Funding; Onyx: Consultancy, Research Funding.

Abstract Abstract 1409 MYC is among the most prolific oncogenes in cancer, yet pharmacologic strategies to modulate the function of the c-Myc oncoprotein do not exist. Toward this objective, we have undertaken to target c-Myc transcription by interfering with chromatin-dependent signal transduction to RNA polymerase, specifically by inhibiting the acetyl-lysine recognition domains (bromodomains) of putative co-activator proteins implicated in transcriptional initiation and elongation. Using a selective small-molecule bromodomain inhibitor, JQ1, we identify BET bromodomain-containing proteins as transcriptional regulatory factors for c-Myc. BET inhibition with JQ1 rapidly downregulates c-Myc transcription, followed by depletion of chromatin-bound c-Myc and genome-wide downregulation of Myc-dependent target genes. In translational model systems of multiple myeloma and Burkitt's lymphoma, both canonical MYC -dependent hematologic malignancies, JQ1 treatment produces a potent antiproliferative effect associated with cell cycle arrest. In multiple myeloma, adhesion to bone marrow stroma is associated with upregulation of BRD4, a BET bromomdomain coactivator protein. Inhibition of Myc function with JQ1 leads to impaired adhesion to stroma and cellular senescence, a classical Myc-specific phenotype. Mechanistically, JQ1 treatment depletes BRD4 from IgH enhancers, leading to prompt and robust downregulation of MYC transcription. In vivo efficacy of JQ1 in two disseminated models of multiple myeloma and in a Burkitt's lymphoma human xenograft establishes the therapeutic rationale for BET bromodomain inhibition in these diseases. Together, these studies identify a mechanistic rationale for targeting c-Myc in human cancer, and potentially other undruggable oncogenes driven by immunoglobulin rearrangement. Note: G.C.I. and J.E.D. have made equal contributions to this research; C.S.M. and J.E.B. are jointly senior authors Disclosures: Richardson: Millennium: Advisory Board; Celgene: Advisory Board; Johnson & Johnson: Advisory Board; Novartis: Advisory Board; Bristol Myers Squibb: Advisory Board. Ghobrial:Bristol-Myers Squibb: Research Funding; Millennium: Research Funding; Noxxon:; Millennium:; Celgene:; Novartis:. Anderson:Celgene: Consultancy, Honoraria; Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Kung:Novartis Pharmaceuticals: Consultancy, Research Funding. Mitsiades:Millennium Pharmaceuticals: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Novartis Pharmaceuticals: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Merck: Consultancy, Honoraria; Kosan: Consultancy, Honoraria; Pharmion: Consultancy, Honoraria; Centocor: Consultancy, Honoraria; Amnis Therapeutics: Consultancy, Honoraria; PharmaMar:; OSI Pharmaceuticals: Research Funding; Amgen: Research Funding; AVEO Pharma: Research Funding; EMD Serono: Research Funding; Sunesis: Research Funding; Gloucester Pharmaceuticals: Research Funding; Genzyme: Research Funding; Johnson & Johnson: Research Funding. Bradner:Acetylon Pharmaceuticals: Scientific Founder; SHAPE Pharmaceuticals: Scientific Founder; Tensha Therapeutics: Scientific Founder.

Recent studies have shown decreased megakaryocyte expression of the thrombopoietin receptor (c-mpl) in patients with polycythemia vera (PV) but not in those with reactive erythrocytosis. We examined the diagnostic utility of this observation in 22 patients with PV, 7 patients with secondary erythrocytosis (SE), and 10 normal controls. Commercial antibodies against c-mpl were used with standard immunoperoxidase methods. Megakaryocyte c-mpl staining intensity was uniformly moderate-to-strong in the healthy controls and in all the patients with SE. In contrast, staining intensity in 9 patients with PV (41%) was uniformly weak. Furthermore, in 12 of the remaining 13 patients with PV, the c-mpl staining pattern in each case was heterogeneous and was associated with weak staining intensity in more than 20% of the megakaryocyte population. These preliminary data suggest that c-mpl immunostains may complement bone marrow histopathology in distinguishing PV from nonclonal causes of erythrocytosis.

Abstract Recent studies have shown decreased megakaryocyte expression of the thrombopoietin receptor (c-mpl) in patients with polycythemia vera (PV) but not in those with reactive erythrocytosis. We examined the diagnostic utility of this observation in 22 patients with PV, 7 patients with secondary erythrocytosis (SE), and 10 normal controls. Commercial antibodies against c-mpl were used with standard immunoperoxidase methods. Megakaryocyte c-mpl staining intensity was uniformly moderate-to-strong in the healthy controls and in all the patients with SE. In contrast, staining intensity in 9 patients with PV (41%) was uniformly weak. Furthermore, in 12 of the remaining 13 patients with PV, the c-mpl staining pattern in each case was heterogeneous and was associated with weak staining intensity in more than 20% of the megakaryocyte population. These preliminary data suggest that c-mpl immunostains may complement bone marrow histopathology in distinguishing PV from nonclonal causes of erythrocytosis.

Abstract Context and objective Approximately 5-10% of diffuse large B-cell lymphoma (DLBCL) patients carry MYC gene translocations (MYC-translocation+) with a poor prognosis after standard chemotherapy. MYC-translocation+ DLBCL patients carrying BCL2 translocations (MYC+/BCL2+ double-hit lymphoma) have a worse survival. The efficacy of adjuvant radiotherapy in this setting is unknown. The purpose of this study is to evaluate the efficacy of radiotherapy as a part of the therapeutic regimen for patients with MYC-translocation+ DLBCL. Patients and methods From the International DLBCL R-CHOP consortium program, we selected 581 patients with de novo DLBCL treated with standard R-CHOP immunochemotherapy (diagnosed and treated from 2000 to 2010). We excluded patients with transformed DLBCL, primary mediastinal, cutaneous, testicular or central nervous system large B-cell lymphomas, patients with HIV infection, and patients not treated with R-CHOP. The median follow-up was 54.9 months. Fluorescence in situ hybridization assessing MYC was performed for all the patients (n=581) and results were correlated with available clinical data to identify clinicopathologic features associated with MYC translocation, and to evaluate the prognostic significance of MYC translocations regarding overall survival (OS, from the time of diagnosis to death from any cause) and progression-free survival (PFS, from the time of diagnosis to relapse or death from any cause). In the MYC-translocation+ DLBCL group, 38 patients received chemotherapy alone and 21 patients received chemotherapy with adjuvant radiation therapy. The clinicopathologic features and survival of MYC-translocation+ DLBCL patients treated with (n=21) and without radiotherapy (n=38) after immunochemotherapy were compared to in order to evaluate the radiotherapy efficacy and other confounding factors. Results MYC translocations were detected in 59 DLBCL patients (10.2%). Patients with MYC-translocation+ DLBCL more often had bulky tumors, involvement of multiple extranodal sites, and poorer OS (hazard ratio [HR]: 2.0, 95% confidence interval [CI]: 1.20 - 3.35, P= .0083) and PFS (HR: 1.96, 95% CI: 1.22 - 3.13, P= .0005) independent of the International Prognostic Index score. Poor survival was primarily attributable to patients with MYC+/BCL2+ double-hit DLBCL who were predominantly of germinal center B-cell subtype. Among MYC-translocation+ DLBCL patients, a better survival was achieved in patients who received radiotherapy (for OS, HR: .32, 95% CI: .15 - .71, P= .0049; for PFS, HR: .35, 95% CI: .17 - .73, P= .0043). Conversely, radiotherapy abolished the adverse impact of MYC translocations. In addition, radiotherapy was associated with better survival in the subset of patients with MYC+/BCL2+ double-hit lymphoma (P = .017 for OS, and P = .05 for PFS). However, owing to the common use of radiotherapy as consolidation therapy, the favorable prognoses in the group of patients who received radiotherapy could also be attributed to limited-stage disease and more frequent complete remission (CR) after first-line treatment and therefore these factors confound interpretation of the data. To address these issues, we evaluated radiotherapy efficacy in separate patient groups: patients who achieved CR, non-CR (PR/SD/PD) patients, and patient with stage I/II, or stage III/IV disease. The efficacy of radiotherapy appeared more apparent in patients with advanced disease who did not achieve CR after first-line chemotherapy. Multivariate analysis after adjustment for stage and IPI score validated that radiotherapy significantly improved OS (HR: .28, 95% CI: .10 - .81, P= .018) and PFS (HR: .32, 95% CI: .13 - .80, P= .015) of MYC-translocation+ DLBCL patients. Conclusions The presence of MYC translocations in DLBCL is an important biomarker that facilitates prognostic prediction and treatment stratification independent of the IPI score. For chemoresistant MYC-translocation+ DLBCL patients, radiotherapy seems to be an effective adjuvant regimen likely due to the higher frequency of extranodal involvement and bulky disease in MYC-translocation+ DLBCL patients. Our results provide a rationale for larger scale studies to assess the potential role of radiotherapy in the management of MYC-translocation+ DLBCL patients, particularly patients with MYC+/BCL2+double-hit DLBCL. Disclosures: Winter: Millenium: Research Funding; Novartis : Research Funding; Pfizer (Wyeth): Research Funding; Seattle Genetics: Research Funding; Spectrum: Research Funding; Janssen (Pharmacyclics): Research Funding; Spectrum (Allos): Consultancy; Sanofi Aventis: Consultancy; Tgen: Consultancy; AMBIT Biosciences (Spouse): Research Funding; Celgene (Spouse): DSMB, DSMB Other, Research Funding; Ariad Pharmaceuticals (Spouse): Research Funding; Novartis (Spouse): Consultancy, Research Funding; Amgen (Spouse): Consultancy, Research Funding; Astellas (Spouse): Research Funding; Caremark/CVS: Consultancy; Pfizer (Spouse): Consultancy; Sanofi Aventis (Spouse): DSMB, DSMB Other; Bristol Myers Squibb (Spouse): DSMB, DSMB Other; UptoDate, Inc.(Spouse): Patents & Royalties.

Abstract Abstract 3619 Extramedullary (EM) acute myeloid leukemia (AML) is generally associated with a poor prognosis. We evaluated the baseline characteristics, response and survival characteristics in a subset of patients age ≤ 60 years with de novo AML and EM manifestations at presentation, treated on the Eastern Cooperative Oncology Group E1900 protocol: daunorubicin 45 or 90 mg /m2 x3 days in conjunction with cytarabine 100 mg/m2 × 7 days followed by risk-stratified consolidation. (Fernandez et al New Engl J Med 2009) Methods: Patient baseline characteristics were compared using Fisher's exact test if they were categories and Wilcoxon rank sum tests if they were continuous. Logistic regression models were used for complete remission (CR) rates and Cox regression models were used for overall survival (OS) and disease-free survival (DFS). The univariate models included indication of whether patient had extramedullary disease involvement, adjusted by induction treatment. The multivariate models were further adjusted for age, gender, cytogenetic risk, ECOG PS, WBC, platelets, marrow blast, hemoglobin, peripheral blasts, and secondary AML. All P values were based on 2-sided tests. Results: 58 (8.9%) of 651 patients in the study presented with evidence of EM at diagnosis. Patients with EM disease were younger and presented with higher peripheral WBC counts and circulating blasts than those without. Immunophenotyping did not demonstrate a difference in baseline CD56 expression (p=0.77). Sites of EM involvement included gingival hypertrophy (n= 33), skin (n= 7), central nervous system (n= 6), lymphadenopathy (n=6), mediastinum (n=2) and other (n=6). 3 patients had multiple sites. Cytogenetic risk in the EM subgroup was favorable (8.6%), indeterminate (inadequate/missing) (34.5%), intermediate (37.9%) and unfavorable (19%) and did not differ statistically from those without EM disease. The complete remission (CR) rates were similar for patients with EM disease compared to those patient's without, regardless of the anthracycline dose (univariate model p= 0.93; multivariate model p=0.88. DFS (patients in CR) and OS of patients with EM disease was not significantly different in the univariate (p= 0.99, p=0.49) or multivariate models (p= 0.92, p=0.37), respectively. On multivariate modeling patients with EM AML who received the standard-dose of daunorubicin had a shorter OS (HR 1.86, 95% CI 1.20 to 2.91, p=0.006). OS was not improved in EM patients treated with high-dose daunorubicin (HR 0.62, 95% CI 0.34 to 1.14, p=0.12) (Table). There was a significant difference in OS for patients with EM treated with the 90 mg/m2 dose of daunorubicin compared to patients with EM treated with the 45 mg/m2 dose (multivariate model: HR 0.30, 95% CI 0.12 to 0.76, p=0.01). Conclusion: Younger patients with de novo EM AML are sensitive to higher doses of anthracycline in induction therapy and should be treated in a similar fashion as patients without EM involvement. For both groups the higher doses of anthracycline are recommended as CR rates, DFS and OS are improved. Further evaluation of immunophenotypic and molecular/ genetic characteristics should be undertaken in this subset of patients. Disclosures: No relevant conflicts of interest to declare.

Abstract Hemorrhagic complications remain a challenge with surgical procedures in patients with bleeding disorders. Tonsillectomy and adenoidectomy are some of the most common surgical procedures performed in pediatric patients. Adequate hemostasis in patients with bleeding disorders is centered on comprehensive hemostatic support and dexterous surgical technique. To assess our institutional experience with children and young adults with bleeding disorders that underwent tonsillectomy and/or adenoidectomy we performed a retrospective chart review of all such patients (age< 25 years) over duration of 20 years from July 1992 to July 2012. Nineteen patients were identified. The mean age was 10.2 years (Range 2.5 – 23.2 years) with 13 females and 6 males. The cohort included 2 patients with platelet disorders, 5 patients with von Willebrand disease and 12 patients with factor deficiencies (see table 1). Sixteen patients (84%) underwent tonsillectomy and adenoidectomy, while 3 patients (16%) underwent tonsillectomy only. Pre-operative treatment in the form of coagulation factor infusion (with a goal of 100% factor levels prior to surgery) or DDAVP was given to 16 patients (84%). Nine patients (47%) received anti-fibrinolytic agent, aminocaproic acid, starting pre-operatively for an average of 15.5 days (Range 10 – 36 days) post-operatively. Six patients (32%) received aminocaproic acid only post-operatively for an average of 12 days (Range 7-14 days). One patient received Tranexamic acid for 19 days. Intraoperative hemostasis was achieved by electrocautery in 16 patients (84%) and coblation technique in 2 patients (10%). Surgical hemostasis technique for 1 patient was undocumented, however this patient did not have any bleeding complications subsequently. Ten patients (53%) experienced post-operative hemorrhage including 2 patients (10%) with early (<24 hours) bleeding and 8 patients (42%) with delayed (>24 hours) bleeding from surgical site. Bleeding resolved spontaneously in 2 patients while 8 patients (42%) required interventions such as cauterization (4 patients), extended aminocaproic acid dosing (4 patients), DDAVP (1 patient), DDAVP and tranexamic acid (1 patient), recombinant factor VII (1 patient), Humate-P® (1 patient), Factor VIII infusion (1 patient) and Factor IX infusion (1 patient). Three patients (30% of bleeding patients) required transfusions including 1 patient that received platelet transfusions, 1 patient received PRBCs and another patient received FFP. Recurrent bleeding was noted in 3 patients and the rate was significantly higher in older patients amongst those with bleeding complications (p=0.0189).Table 1Age (years, months)GenderDiagnosisSeverity of diseasePost-operative bleeding (Early ≤ 24 hours, Delayed >24 hours)Recurrent bleeding14,5MEssential ThrombocythemiaModerateEarlyYes13,6MFactor VII deficiencyMildDelayedNo6,7FFactor VII deficiencyMildDelayedNo7,6FFactor VII deficiencyMildNo-11,2FFactor XI deficiencyMildEarlyNo8,4MHemophilia ASevereDelayedNo9,4FHemophilia A carrierMildDelayedNo15,2FHemophilia A carrierMildNo-5,0MHemophilia BMildNo-23,2MHemophilia BMildDelayedYes6,1FHemophilia B carrierMildNo-6,8FHemophilia B carrierMildNo-15,2FHemophilia B carrierMildNo-11,4FMay-Hegglin anomalyModerateDelayedNo4,0FType 1 von WillebrandMildDelayedNo13,5FType 2A von WillebrandModerateDelayedYes2,5MType 2A von WillebrandModerateNo-9,9FType 2B von WillebrandModerateNo9,1FType III von WillebrandSevereNo- The rate of bleeding complications in pediatric patients with mild bleeding disorders undergoing adenotonsillectomy has been reported to be similar to that of normal population. In our cohort, delayed bleeding was more common than early bleeding consistent with current literature. We observed a higher rate of bleeding complications (53%) than reported in literature despite aggressive hemostatic support and adequate surgical techniques; however, our sample size was limited. Although there was no association between delayed hemorrhage and age, recurrent bleeding was associated with older age. We conclude that patients with bleeding disorders undergoing adenotonsillectomy are at a higher risk of bleeding and require close monitoring with hemostatic support for a prolonged period of time in post-operative period. Disclosures: No relevant conflicts of interest to declare.

Abstract Background Waldenstrom macroglobulinemia (WM) is an IgM-associated lymphoplasmacytic lymphoma, first described over seven decades ago. Although WM is typically a disease of the elderly, with a median age at diagnosis of ~ 67 years, approximately 10% of patients are ≤50 years (y) of age at diagnosis. Data for young patients are sparse and the few available studies demonstrate inconsistent findings, with potential overestimation of survival owing to inclusion of patients with smoldering WM. In this case-control study, we evaluate outcomes, prognostic features and impact of changing therapies in a large cohort of young symptomatic WM patients compared to matched older patients seen over the course of the past five decades. Methods The medical records of all WM patients seen consecutively at Mayo Clinic from 01/1960 to 10/2013 were reviewed. Of 1181 patients, 140 (11.8%) were ≤ 50 y of age at diagnosis. A cohort of patients 65 y or older at diagnosis, matched 1:1 by the time of diagnosis, served as the control population. The patients were divided into 3 groups based on the timing of initiation of therapy: Group 1 (1960-1977), Group 2 (1978-1995) and Group 3 (1996-2013). The baseline characteristics were compared. Initiation of frontline therapy was used for all time-to-event analysis using the Kaplan Meier method. Results Younger patients were more likely to present with adenopathy and splenomegaly, have higher IgM levels and hyperviscosity symptoms (Table 1). The median follow-up from the frontline therapy was similar (10.7 y vs. 10 y for the control population). At the time of analysis, 91% of the deaths for the younger cases were WM-related compared to 58% in the control arm (p=0.0001). Younger patients had a better OS with a median disease-specific survival (DSS) of 15.6 y (95% CI: 13-21; 10-y OS of 77%) vs. 11 y (95% CI: 7.8-12; 10-y OS of 51%) for the older patient (p=0.0003). Among the young patients, there was no difference in the median DSS across the 3 groups (p=0.42). However, the median DSS for the control group incrementally improved (p=0.02) over the 3 time periods (Table 1). In the younger patients, no improvement in DSS was noted with the use of either frontline rituximab-based therapy compared to non-rituximab based regimens [median NR (95% CI: 7.6-NR) vs. 15.8 y (95% CI: 13-22) with other regimens, p=0.30], or frontline chlorambucil-based compared to non-chlorambucil based regimens [median 16 y (95% CI: 12-22) vs 15.6 y (95% CI: 12-NR) with other regimens, p=0.73]. In the control group, however, there was significant difference in DSS among patients who received frontline rituximab-based compared to non-rituximab based regimens [median NR (95% CI: 8.3-NR) vs 9.1 y (95% CI: 5.6-12) with other regimens, p=0.04], or frontline chlorambucil-based vs non-chlorambucil based regimens [8 y (95% CI: 5-12) vs 12.3 y (95% CI: 11-NR) in other regimens; p=0.001]. Conclusion Striking differences in presentation are evident in young WM patients compared to their older counterparts. The incorporation of rituximab to the previously existing anti-WM regimens and the transition to non-chlorambucil based regimens has resulted in substantial survival gains in the older WM population over the past five decades. However, such improvement in outcome has not yet been observed in the young patients. The majority of younger patients, despite a protracted disease course, succumb to their disease. Disclosures Ansell: BMS, Seattle Genetics, Merck, Celldex and Affimed: Research Funding. Ailawadhi:Pharmacyclics: Consultancy; Novartis: Consultancy; Amgen Inc: Consultancy; Takeda Oncology: Consultancy. Reeder:Novartis: Research Funding; Celgene: Research Funding; BMS: Research Funding; Millennium: Research Funding. Kumar:Kesios: Consultancy; Janssen: Consultancy, Research Funding; Sanofi: Consultancy, Research Funding; AbbVie: Research Funding; BMS: Consultancy; Onyx: Consultancy, Research Funding; Glycomimetics: Consultancy; Millennium: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Noxxon Pharma: Consultancy, Research Funding; Array BioPharma: Consultancy, Research Funding; Skyline: Honoraria, Membership on an entity's Board of Directors or advisory committees. Dispenzieri:Alnylam: Research Funding; Celgene: Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Prothena: Membership on an entity's Board of Directors or advisory committees; GSK: Membership on an entity's Board of Directors or advisory committees; pfizer: Research Funding; Jannsen: Research Funding. Kapoor:Celgene: Research Funding; Takeda: Research Funding; Amgen: Research Funding.

Abstract Background: Unlike acute lymphoblastic leukemia, data on acute myelogenous leukemia (AML) in the adolescents and young adults (AYA) are limited and generally derived from clinical trials, which are mostly conducted in academic centers. It is unclear whether the choice of treatment facility influences clinical outcome independent of disease biology and socio-demographic factors. This study used the National Cancer Data Base, a nationwide oncology database covering 70% of the US cancer population, to address this question. Methods: We identified 11,712 AYA patients who were diagnosed with AML from 2003-2011. We excluded patients who were: a) 15-17 years of age (n = 3,104) as treatment facility data were not available for age <18 years; b) not treated at the reporting facilities (n = 415) as follow-up might be incomplete; c) treated at treatment facilities with ≤100 new cancer cases/year (n = 18); and d) those without follow-up data (n = 47). Treatment facilities were classified as academic, comprehensive community (>500 new cancer cases/year), or community (101-500 new cancer cases/year) cancer programs. AMLs harboring t(15;17), inv(16), or t(8;21) were defined as good-risk, while the rest were considered non-good risk. Overall survival from the time of AML diagnosis was the primary outcome. We used multivariate imputation by chained equation to impute missing values, weighted Cox regression to obtain average hazard ratios (HRs), and pooled Wald c2 statistics to detect interaction. Results: We included 8,128 AYA patients with AML in the study and 25.2% were good risk. Among the good risk AMLs, 11.6%, 12.3%, and 76.1% had t(8;21), inv16, and t(15;17), respectively. The distribution of patients by treatment facility were academic (64.1%), comprehensive community (32.9%), and community (3.0%). After detecting an interaction between AML risk and type of treatment facility (P=0.038), we stratified treatment facility by AML risk and found significant differences in overall survival among good risk (P=0.02) but not non-good risk AML (P=0.19). This survival difference persisted even after adjusting for demographic (age, sex, race/ethnicity), socioeconomic (income, education, medical insurance), geographic (area of residence, travel distance), co-morbidities (Charlson-Deyo score), and treatment (receipt of chemotherapy) factors. Patients with good risk AML treated in comprehensive community cancer programs had a higher risk of death compared to those treated in academic programs (adjusted HR: 1.41, 95% CI: 1.11-1.79). For community cancer programs, the risk of death was also higher but did not reach statistical significance (adjusted HR: 1.22, 95% CI: 0.68-2.21). ). Subset analysis showed that the survival difference among those with good risk AML was observed in t(15;17) or acute promyelocytic leukemia (APL; P=0.02) but not in t(8;21) or inv16 (P=0.79). The disparity occurred primarily during the first month of APL diagnosis, wherein the risk of death was two-fold higher in community programs (Figure). Conclusions: Among AYA patients with AML, treatment at academic cancer programs was associated with a better survival, but only for the APL subgroup. Because APL comprises a fifth of all AMLs in the AYA and is a highly curable cancer, health care delivery research in APL should become a priority in this age group. Figure 1. Figure 1. Disclosures Al-Kali: Celgene: Research Funding.

Abstract Introduction: Slow rate of myeloid recovery at the end of induction chemotherapy reflected by a low absolute neutrophil count (ANC) is highly predictive of relapse in children with ALL (Laughton et al, 2005). Whether rate of myeloid recovery is predictive of outcome post-hematopoietic stem cell transplantation (HSCT) in children and young adults has not been studied. Objective: To explore the association between early ANC recovery and survival in children and young adults undergoing allogeneic and autologous HSCT for leukemia or lymphoma. Methods: Retrospective chart review was performed for all consecutive patients (age 6 months to 21 years) undergoing first HSCT for hematologic malignancies and lymphomas at Mayo Clinic, Division of Pediatric Hematology/Oncology from 1995 to 2004. Day 15 and day 28 ANC were calculated for all patients. The primary end point was 1-year relapse free (RFS) and overall survival (OS). To explore the association between ANC and primary outcome, patients were stratified in 2 groups: ≥ or < than median ANC and Kaplan Meier survival curves were generated for both the groups and compared with the log-rank test. Matched related donor (MRD), matched unrelated donor (MUD) and haploidentical (as one group) and autologous transplantations were analyzed separately. Results: There were a total of 50 patients. 28 received MRD, 2 MUD, 10 haploidentical and 10 autologous. The underlying malignancies were (AML n =25, Biphenotypic Leukemia n=1, ALL n =7, NHL n=3, HD n=7, JMML n=5, CML n=2, CLL n=1). No patient was lost to follow up during that time and data was available for all except (day 28 ANC) for one patient. The 1-year RFS and OS rate was the same; 81% for the MRD, 50% for MUD and haploidentical and 70% for autologous transplant populations, respectively. In patients receiving MRD transplants, higher ANC at either day 15 or day 28 post transplantation was associated with better, albeit statistically non-significant, RFS/OS rates at 1 year (86% for ≥ median (0.68) vs. 76% for < median p=0.44 and 92% for ≥ median (2.2) vs. 72% for < median p= 0.18 respectively). Opposite results were observed for MUD and Haploidentical transplantation group (33% for ANC ≥ median (0.47) at day 15 vs. 66% for < median p=0.28, 43% for ANC ≥ median (1.9) at day 28 vs. 60% for < median p=0.48). For autologous transplant group, higher ANC at day 15 was associated with better, albeit statistically non-significant, RFS/OS rates at 1 year (80% for ANC ≥ median (0.42) vs. 60% for < median p=0.60) while opposite results were observed on day 28 (60% for ANC ≥ median (0.46) vs. 75% for < median p=0.54). Conclusions: Our data generated conflicting findings of the association between ANC and RFS/OS in different patient populations undergoing HSCT. However, our results are limited by the small sample size. Further collaborative studies are needed to explore this association.