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Key Points The ClinGen MM-VCEP has specified RUNX1-specific curation rules to address gene function, gene-specific domains, and phenotypic criteria. RUNX1-specific criteria resulted in a reduction in CONF and VUS variants by 33%, emphasizing the need for expert variant curation.

Abstract Background: We previously demonstrated that putative clinical epidemiologic exposures associated with leukemia risk are prevalent among AML patients, and some are associated with unique cytogenetic risk group and with clinical phenotype (Finn, Cancer Epidemiol, 2015). Herein, we studied genome-wide DNA methylation in a cohort of AML patients to evaluate the association of individual hyper- and hypo-methylated CpG sites with epidemiologic exposures and overall survival. Methods: The Mayo Clinic AML Epidemiology Cohort is a highly annotated retrospective case series of 295 consecutive patients (pts) with AML diagnosed and treated at Mayo Clinic Florida and Arizona, with central cytogenetics performed in all cases. The prevalence of clinical epidemiologic exposures, past medical and family history as well as medication use and lifestyle was systematically obtained. After IRB approval, we interrogated the cytogenetic database and successfully obtained leukemia DNA from available remnant diagnostic cytogenetic cell pellets in a cohort of 148 AML patients in the Mayo epidemiology case series and performed an assessment of genome-wide DNA methylation using the Infinium HumanMethylation450K BeadChip. Samples were processed using the R Bioconductor package 'minfi' using Subset Within Array Quantile Normalization (PMID: 22703947). Individual CpGs that did not reach a detection p-value of <0.05 were filtered out. An internal control was included on each array to control for significant batch effects. To determine differential methylation status of 473,864 individual CpG sites (after exclusion of 11,648 that did not pass detection p-value QC), CpG sites with low interpatient variability, a standard deviation <0.05 of methylation values, and an interquartile range <0.05 of methylation values and X/Y chromosome probes were excluded from analysis. Epidemiologic and important clinical variables occurring in at least 10 pts or previously-identified as of unique interest but in fewer than 10 pts were evaluated, including sex, BMI, performance status and comorbidities, tobacco and alcohol use, family history of hematologic malignancy, medications of interest, history of toxin exposure, and history of immunosuppression and/or solid organ transplant or of secondary and therapy-related AML (t-AML). Associations of differential hypo or hypermethylation at 281,259 CpG sites with epidemiologic exposures/clinical variables were evaluated using Spearman's test of correlation (continuous or ordinal exposures), a Wilcoxon rank sum test (dichotomous exposures), or a Kruskal-Wallis rank sum test (multi-category exposures). A Bonferroni correction was applied for multiple testing, after which p <1.8 x 10-7 was considered as significant. To reduce the likelihood of false-negative findings, we additionally considered p <5 x 10-6 as indicating suggestive evidence of an association. CpG sites and associated gene and function was determined using Illumina manifest file & www.ncbi.nlm.nih.gov/gene. Results: Statistically significant associations (p <1.8 x 10-7) with individual epidemiologic and clinical exposures were identified for 109 unique CpG sites, corresponding to differential methylation in the genes listed in Table. Specifically, obesity (predominantly hypomethylation), specific cytogenetic lesions and risk group, and gender were highly significantly associated with unique CpG methylation status, but not smoking, toxin exposure, family history, comorbidity or performance status, secondary or t-AML, immunosuppression, medication use, of family history in the analysis. A further 353 unique CpG sites had defined suggestive associations (ongoing analysis). We also identified 8 additional CpG sites where differential methylation was associated with overall survival (p <5 x 10-6, Table). Conclusion: Obesity, cytogenetic lesions, and sex are associated with differential methylation of unique CpG sites at AML diagnosis, using stringent univariate statistical criteria. Significant CpG sites were identified in genes previously linked to AML biology and prognosis (DOCK6, HOXB3, MIR10A, FOXN3/CHES1, GPX1, MYST2/KAT7, PTPRD), but some represent novel findings in AML. These preliminary results suggest an association of some AML risk factors and clinical variables with unique gene methylation and will undergo validation in a prospective AML epidemiology dataset. Disclosures Cerhan: Jannsen: Other: Scientific Advisory Board; Nanostring: Research Funding; Celgene: Research Funding. Foran:Agios: Research Funding; Xencor, Inc.: Research Funding.

Abstract Introduction: We previously demonstrated that engagement of the T-cell receptor (TCR) in malignant T-cells leads to ITK-dependent activation of the transcription factors NF-κB and GATA3, thus promoting chemotherapy resistance. TCR-mediated chemotherapy resistance was reversed upon knockdown or pharmacologic inhibition of ITK (Wang, 2017). ITK and resting lymphocyte kinase (RLK) are partially redundant TEC family kinase members involved in TCR signaling (Dubovsky, 2013). Here, we report results from preclinical studies evaluating the use of the ITK-specific inhibitor CPI-818 and the dual ITK/RLK inhibitor CPI-893 in the treatment of T-cell lymphoproliferative disorders. Methods/Results: Kinome screening was performed for CPI-818 and CPI-893. CPI-818 had high specificity for ITK over RLK (IC50 2.3 nM and 260 nM, respectively). In contrast CPI-893 had a high affinity for both ITK and RLK (IC50 0.36 nM and 0.4 nM, respectively). Normal and malignant T-cells from primary patient samples were evaluated for both ITK and RLK by western blot. As anticipated, normal CD3+ T-cells isolated from healthy donors expressed both ITK and RLK (n=3/3). In contrast, malignant T-cells preferentially expressed ITK in 3 of 3 cases and low levels of RLK in a single case. Tissue microarray analysis of cutaneous T-cell lymphoma and peripheral T-cell lymphoma cases further demonstrated ITK expression across multiple subtypes. To confirm on target effects of CPI-818 and CPI-893, Jurkat cells (which express ITK but not RLK) were stimulated with anti-CD3/CD28 beads for 5 minutes in the presence or absence of either agent. Auto-phosphorylation of ITK Y180 and PLC-γ Y783, an ITK substrate, were significantly reduced in the presence of either agent, confirming on target effects. We next evaluated the effect of both drugs on GATA3 expression. Cells were stimulated for 24 hours with anti-CD3/CD28 beads in the presence or absence of these agents (or vehicle control). ITK inhibition with either agent significantly reduced GATA3 expression in these experiments. We next evaluated the effect of CPI-818 and CPI-893 on cell viability in normal T-cells. TCR stimulation for 24 hours increased viability by 359% in the presence of vehicle control when normalized to unstimulated cells (n=3). Treatment with 1 µM CPI-893 reduced the cell viability to only 133% when compared to unstimulated controls (n=3, p = 0.0045). In contrast, treatment with the ITK-specific inhibitor CPI-818 at 1 µM had a numerically smaller, but still statistically significant effect (n=3, average viability 278%, p = 0.0056). We next quantified IL-10 expression by ELISA in cell culture supernatants. Consistent with the observed effect on cell proliferation and viability, only CPI-893 significantly reduced IL-10 production upon TCR stimulation (886 pg/mL vs 11.7 pg/mL, p <0.0001). In order to assess TCR-mediated resistance to chemotherapy in malignant T-cells, T8ML-1 cells (PTCL, NOS cell line) were incubated in the presence or absence of CPI-818 or CPI-893 (both 1 µM) with varying concentrations of vincristine. When compared to TCR-stimulated cells alone, both agents displayed single agent activity, but also sensitized the cells to the effects of vincristine. The IC50 for vincristine in unstimulated cells, TCR-stimulated cells, CP-818 treated stimulated cells, and CPI-893 treated stimulated cells was 0.049, 0.443, 0.066, and 0.091 nM, respectively (n=4 per group). Similar results were observed in primary patient samples treated with romidepsin. Consistent with the observed effect on proliferation and viability, IL-10 production was decreased when compared to TCR stimulated controls (15.97 pg/mL, n=3 for each group) with both CPI-818 (3.47 pg/mL, p <0.0001) and CPI-893 (2.3 pg/mL, p <0.0001). Conclusions: Our results demonstrate that TCR signaling inhibition with the selective ITK inhibitor CPI-818 significantly impaired malignant T-cell growth and proliferation, increased chemotherapy sensitivity, and decreased GATA3 expression. In contrast, this agent had minimal effect on normal T cells; this is likely explained by the expression of both ITK and RLK in most conventional T-cells. Collectively, our data support further preclinical and clinical studies with CP-818 in T-cell lymphoproliferative disorders. Disclosures Buggy: Corvus Pharmaceuticals, Inc.: Employment, Equity Ownership. Janc:Corvus Pharmaceuticals, Inc.: Employment, Equity Ownership. Wilcox:Incyte, Corp: Research Funding.

Abstract Introduction: Chronic myelomonocytic leukemia (CMML) is a chronic myeloid malignancy associated with monocytosis, autoimmunity (~30%) & an inherent risk for leukemic transformation. Bone marrow (BM) dendritic cell (DC) populations occur in ~30% of patients, with a poorly defined biological & prognostic role. The malignant immune microenvironment is regulated by indoleamine 2,3-dioxygenase-1 (IDO-1) expressing DCs, which modulate regulatory T (Treg) cells & block their conversion into proinflammatory T helper (Th17)-like cells. IDO-1 is a known immune checkpoint & functions by catabolizing tryptophan, an amino acid essential for T cell function. We hypothesized that distinct IDO-1 expressing DC populations in CMML modulate Tregs & contribute towards immune tolerance & aggressive disease biology. Methods: Primary diagnostic CMML peripheral blood mononuclear cells (PBMC) & BM biopsy specimens were obtained after Mayo Clinic IRB approval. A DC population was defined on H&E stained biopsy sections as focal collections (>10) of cells with characteristic elongated nuclei & cytoplasmic extensions. Transcriptomic & protein expression studies assessing IDO-1 expression were done by previously described methods. In addition, IHC expression of PD-1, PD-L1 & CTLA-4 was also done. IDO-1 promoter methylation studies with DIP-seq were performed. The impact on immune tolerance was assessed using mass cytometry (CyTOF). Results: Cohort: Twenty eight patients with CMML were included in the study, median age 70 (range: 51-80) years; 71% males. Eleven (39%) patients had coexisting autoimmune conditions. Of these, 8 (73%) had detectable DC populations either at diagnosis, or during the course of their disease. At a median follow-up of 46 (95% CI 27, 84) months, there were 14 (50%) deaths & 9 (32%) leukemic transformations.IHC results: Nine (32%) patients were identified to have a DC population at CMML diagnosis. CD123 & TCL1 staining was performed in 5 (56%) patients, with 3 being positive for both, & 2 positive for CD123 only (additional IHC studies ongoing). IDO1 expression by IHC was documented in all 9 (100%) cases (Fig 1A & 1B), while rare populations of PD-1, PD-L1 & CTLA-4 lymphocytes were also seen in all cases. Due to the low DC burdens (median cellularity ≤ 5%) & uniform staining intensity, IHC-based grading was not done. Samples at serial time-points, post-HMA therapy & at the time of blast transformation, were available in 5 & 3 patients respectively. Among the patients who did not have DC populations at diagnosis, 5 (42%) developed them post-HMA therapy, while 3 (50%) developed them at the time of LT. The development of DC populations was associated with loss of response to HMA (50%) & disease progression (50%).Transcriptomic analysis: RNA expression data was available on 7 (25%) patients, of whom only 1 (14%) had DC populations at diagnosis. The IDO-1 RPKM value in the former was higher than the mean pooled value in the latter group (330 versus 74, p=0.05).Methylation studies: DIP-seq was performed on 12 (43%) cases from the primary IHC cohort. Qualitative analysis of IDO-1 promoter hypomethylation was conducted & confirmed in all 9 (100%) cases with 5-mC & 5-hmC marks compared to input as displayed in figure 1C.Immune profiling: CyTOF was performed on 4 CMML samples (3 with IDO-1 expressing DC populations at diagnosis) from the primary IHC cohort & compared to a normal PBMC control. Results confirmed an increase in DC populations (fig 1D& 1E), & reduced % of Th17-like T cells in CMML samples compared to control (1.1 versus 5.07, p=0.05, fig 1F).Clinical correlates & survival analysis: With the exception that CMML patients with DC populations had a higher frequency of NRAS (P=0.007) mutations, the two groups were comparable for cytogenetic & molecular abnormalities. The median OS for the cohort was 45 (95% CI 29, 84) months. CMML patients with IDO-1 expressing DC populations at diagnosis had a shorter median OS, in comparison to those without (median OS 30 vs 45, p=0.03, Kaplan-Meier analysis in fig 1G). Conclusions: In conclusion, we demonstrate that DC populations are seen in ~30% of patients with CMML with a uniform expression of IDO-1 & limited expression of PD-1, PD-L1 & CTLA-4. CMML patients with BM DC populations have a higher frequency of NRAS mutations & DC IDO-1 expression is associated with tumor induced immune tolerance. Additional IHC, genomic & preclinical studies with IDO-1 inhibitors are ongoing. Figure 1. Figure 1. Disclosures Al-Kali: Novartis: Research Funding.

Abstract Dasatinib with corticosteroid yields high complete remission (CR) rates in Ph+ ALL with minimal induction death. Optimal post-remission therapy is not known. We report a prospective study evaluating dasatinib/dexamethasone induction then consolidation with reduced-intensity conditioning (RIC) allogeneic hematopoietic cell transplantation (alloHCT), autologous HCT (autoHCT), or chemotherapy alone (chemo), followed by dasatinib-based maintenance. Methods: We conducted a phase II, 3-arm, non-randomized trial (NCT01256398, Support: U10CA180821, U10CA180882, U10CA180861, U24CA196171) at 17 US centers with primary objectives to determine 3-year overall survival (OS) and disease-free survival (DFS) of adults ≥18 years (yrs) old with untreated Ph+ ALL treated with dasatinib/dexamethasone induction, CNS prophylaxis with systemic and intrathecal methotrexate, consolidation with alloHCT, autoHCT, or chemo, then dasatinib maintenance. Induction (Course I) used dasatinib 140 mg orally daily and dexamethasone 10 mg/m2/day orally or IV days 1-7. If ≤20% lymphoblasts in marrow at Day 15, Course II continued dasatinib with 7 days of dexamethasone. If >20% lymphoblasts, patients (pts) also received vincristine and daunorubicin. Pts not in CR/CRi received a second induction (Course III) with dasatinib, cyclophosphamide, vincristine, daunorubicin, and dexamethasone. CNS prophylaxis (Course IV) used dasatinib, IV vincristine and IV, oral, and intrathecal methotrexate. Course V consisted of HCT or chemo. Pts 18-70 yrs old underwent RIC alloHCT if they had a HLA-matched donor; otherwise they underwent autoHCT. AlloHCT conditioning used fludarabine 30 mg/m2/day IV day -7 through -3, alemtuzumab 20 mg/day IV day -7 through -3, and melphalan 140 mg/m2 IV once on day -2. GVHD prophylaxis with tacrolimus began day -2. Pts undergoing autoHCT received etoposide 10 mg/kg/day (age >65, 5 mg/kg/day) CIV for 4 days and cytarabine 2 g/m2 (age >65, 1 g/m2) IV every 12 hours for 8 doses then G-CSF for mobilization. AutoHCT conditioning was melphalan 100 mg/m2/day IV on days -2 and -1. Pts >70 yrs old or unable to undergo HCT received etoposide/cytarabine alone. Dasatinib maintenance (Course VI) began day 30 of Course V and continued for 12 months and until 2 consecutive negative BCR-ABL1 RT-PCR assays 3 months apart or relapse. BCR-ABL1 isoform and ABL1 kinase domain (KD) mutation determination were done locally. Results: From 12/15/2010 to 11/14/2014, 64 eligible pts enrolled. Median age was 60 yrs (22-87); median WBC 23.2 x 103/μl (0.3-454). The dominant BCR-ABL1 isoform was p190 in 59%, p210 in 17%, and not reported in 23%. The CR rate was 97% with no induction deaths. Fifty-five pts completed CNS prophylaxis (Course IV). Twenty pts underwent protocol-specified alloHCT, 7 autoHCT, and 9 chemo. Nine pts underwent off-study alloHCT and 5 skipped Course V. Dasatinib maintenance was tolerable with 72%, 80%, and 80% receiving >50% of planned maintenance doses in alloHCT, autoHCT, and chemo arms, respectively. With a median follow up of 48 months (37-78) for survivors, 3-yr OS and DFS were 55% (median OS 45 months) and 43% (median DFS 30 months), respectively. For pts undergoing consolidation with protocol-specified alloHCT, autoHCT, or chemo, 3-yr OS was 75%, 71%, and 55% respectively with median OS not reached (NR) for all groups. DFS at 3-yrs was 55%, 43%, and 46% respectively. Median DFS for alloHCT was 42 months vs 15 months for autoHCT and 34 months for chemo (Log-Rank P=0.4). Outcomes were similar with inclusion of off-study alloHCT and chemo patients skipping Course V. Relative to p190 BCR-ABL1 isoform, p210 was associated with shorter median OS (NR vs 16 months, P=0.04) and median DFS (35 months vs 10 months, P<0.0001). Three-year DFS was 9% with p210. Relapse occurred in 23 pts with 5 CNS relapses reported, one isolated. Relapse occurred in 25% of alloHCT, 43% of autoHCT, and 37% of chemo pts. T315I mutation in ABL1 KD was detected in 6 of 8 marrow relapses (75%). One isolated CNS relapse had no ABL1 KD mutations. Conclusions: Dasatinib and dexamethasone followed by alloHCT, autoHCT, or chemo yield similar 3-yr survival comparable to approaches using intensive induction chemotherapy. Pts with the p210 BCR-ABL1 isoform had dismal outcomes and may benefit from alternate approaches. T315I mutation was the major cause of relapse and should be addressed in future studies. Disclosures Wieduwilt: Amgen: Research Funding; Reata Pharmaceuticals: Equity Ownership; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees; Leadiant: Research Funding; Shire: Research Funding; Merck: Research Funding. Uy:GlycoMimetics: Consultancy; Curis: Consultancy. Powell:Rafael Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Kolitz:Magellan Health: Consultancy, Honoraria. Liedtke:Caelum: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen/Onyx: Consultancy, Honoraria, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; celgene: Research Funding; Genentech/Roche: Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Prothena: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BlueBirdBio: Research Funding. Stock:Jazz Pharmaceuticals: Consultancy. Devine:Kiadis Pharma: Consultancy. Larson:BristolMyers Squibb: Consultancy, Research Funding; Ariad/Takeda: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding.

Abstract Background: Polycythemia vera (PV), essential thrombocytosis (ET), and myelofibrosis (MF) are chronic myeloproliferative neoplasms (MPNs) characterized by clonal cell proliferation, splenomegaly, and significant symptom burden. Integrative medicine interventions may offer unique symptom management strategies. (Gowin, et al., EHA 2017). Here we describe integrative interventions utilized and association with symptom burden, quality of life, depression, and fatigue adjusted for lifestyle confounders. Methods:Patients were recruited via social media. Consent and online self-report surveys were completed capturing patient demographics, disease-specific data, integrative medicine utilization, symptom burden via MPN-Symptom Assessment Form Total Symptom Score (MPN-SAF TSS), depression screening via Patient Health Questionnaire (PHQ)-2, fatigue via Brief Fatigue Inventory (BFI), and overall quality of life (QoL). MPN-SAF TSS, QoL, BFI, and PHQ2 were compared by participation in the most frequently utilized interventions (Yes vs No). Intervention comparisons were adjusted for alcohol consumption, smoking status, BMI, current dietary modification, and MPN type using multiple linear and logistic regression. Results: Patients: A total of1087 patient surveys were consented. Of these, 858 had 10 or more responses. See Table 1 for patient characteristics. Integrative Medicine Therapies Descriptive Analysis: Integrative medicine therapies most frequently utilized by patients included aerobic activity (51.5%), massage (28.4%), yoga (25.6%), nutrition (25.2%), strength training (23.8%), acupuncture (19.3%), meditation (19%), breathing exercises (18.4%), chiropractic (16.2%), support groups (14.5%), mindfulness based stress reduction (13.6%), walking meditation (12.0%), pet therapy (9.4%), aromatherapy (8.6%), music therapy (8.0%), progressive muscle relaxation (7.0%), guided imagery (6.4%), homeopathy (6.3%), manual therapy (osteopathy/cranial sacral) (6.2%), reiki (5.8%), therapeutic touch (5.7%), Tai Chi (5.2%), art therapy (4.9%), traditional Chinese medicine (4.3%), Qigong (3.5%), cooking classes (3.0%), laughter therapy (2.9%), Ayurveda (2.4%), biofeedback (2.2%), dance therapy (2.1%), hypnosis (2.0%), resilience training (0.9%), IV vitamin therapy (0.8%), and narrative medicine (storytelling) (0.3%).Diet modification was reported in 47.7% of patients, including Mediterranean diet (19.0%), paleo/high protein/low carbohydrate (8.9%), vegetarian (8.6), plant based (5.2%), gluten free (5.2%), low FODMAP (1.8%), vegan (1.2%), and raw (0.6%) diets. Only 24% of patients reported receiving nutrition advice from their healthcare practitioner (HCP). Supplement utilization by MPN type was 162 patients (48.4%)in ET, 80 patients (42.8%) in MF, and 142 patients (45.2%) in PV. Overall, 20.6% patients reported not disclosing their natural product usage to their HCP. The most frequently utilized supplements included vitamin D, multivitamin, magnesium, omega 3, and calcium. Adjusted symptom association with integrative therapy intervention: MPN symptom burden: Aerobic activity (P=<.001)and strength training (P=.01) was associated with lower mean symptom burden. Use of massage (P=<001) and support groups (P=<.001) was associated with higher levels of symptom burden. QOL:Higher quality of life was reported in those receiving massage (P=.04)and support groups (P=.002). Lower quality of life was noted in those using aerobic activity (P=<.001)and strength training (P=.001). Depression (PHQ-2):Lower depression screening score was noted in those participating in aerobic activity (P=.006), yoga (P=.03), and strength training (P=.02). Fatigue (BFI):Lower fatigue was noted in those participating in aerobic activity (P=<.001) and strength training (P=.03). Higher fatigue was noted in those participating in massage (P=<.001) and breathing techniques (P=.02). See Table 2. Conclusion: In a geographically diverse MPN patient population, and when adjusting for healthy lifestyle practices overall, patterns of lower symptom burden, fatigue, depression, and higher QoL were revealed with integrative medicine utilization. Although limited by gender discrepancy and patient reported data, this study may offer a foundation to structure future integrative medicine trials to complement standard therapies in MPN patients. Disclosures Gowin: Incyte: Consultancy, Other: Scientific Advisory Board, Speakers Bureau. Mesa:UT Health San Antonio - Mays Cancer Center: Employment; Promedior: Research Funding; NS Pharma: Research Funding; CTI Biopharma: Research Funding; Genentech: Research Funding; Gilead: Research Funding; Incyte Corporation: Research Funding; Novartis: Consultancy; Pfizer: Research Funding; Celgene: Research Funding.

Abstract Background: Acute leukemias of ambiguous lineage (ALAL), including acute undifferentiated leukemia and mixed phenotype acute leukemia (MPAL), are rare hematologic malignancies, accounting for only 2-5% of cases of acute leukemia. Outcomes are generally poor, and retrospective studies have suggested that patients have better outcomes when treated with regimens used for acute lymphoblastic leukemia (ALL) rather than acute myeloid leukemia (AML). Due to heterogeneous definitions and rarity of these leukemias, no single ALL regimen has been studied extensively. Hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone (hyperCVAD) is one of the most widely used adult ALL regimens in the United States. We retrospectively examined the effectiveness of this regimen as initial therapy in patients with ALAL. Methods: We retrospectively reviewed records from adult patients treated initially with hyperCVAD-based chemotherapy for ALAL as defined by the World Health Organization at five academic institutions. Only patients whose diagnosis was verified at a participating institution were examined. Philadelphia (Ph) chromosome-positive ALAL patients treated concurrently with tyrosine kinase inhibitors were included. The primary objective of the study was to determine the overall response rate (ORR) and median overall survival (OS). Descriptive statistics were used for baseline characteristics and responses, and Kaplan-Meier estimates were used to calculate all time-to-event outcomes. Results: Twenty-two patients were identified, and pre-treatment characteristics are shown in the Table. Median age was 50 years (range, 22-69), with an even distribution of male and female patients (50% each). The majority (77%) were Caucasian. Two patients (9%) had acute undifferentiated leukemia, 11 (50%) T/myeloid MPAL, 8 (36%) B/myeloid MPAL, and 1 (5%) B/T MPAL. Seven (32%) had a complex karyotype (at least 3 abnormalities), 6 (27%) had a normal karyotype, 3 (14%) were Ph-positive and were treated concurrently with dasatinib, and 1 (5%) had an 11q23 rearrangement. FLT3-ITD was detected in 5 of 8 patients (63%) with an available mutation panel. Three (15%) had central nervous system (CNS) involvement at presentation, and one additional patient developed CNS disease during the course of therapy. There were no deaths within the first 30 days, and the median number of cycles given was 4 (range, 1-8). The CR rate was 73% (n=16) and an additional 14% (n=3) had CR with incomplete count recovery (CRi), for an ORR rate of 86%. One patient had a partial response, and 2 patients had no response. Of the 19 patients achieving CR or CRi, median number of cycles to CR was 1.5, and 12 (63%) proceeded to allogeneic hematopoietic stem cell transplantation (alloHSCT). Of the 7 responders who did not receive alloHSCT, 3 relapsed shortly after initial CR and 4 are alive and in remission 77, 39, 37 and 10 months from treatment initiation. All 3 patients with Ph-positive disease achieved CR. Only 1 proceeded with alloHSCT and all 3 patients are alive and in remission at 51, 39, and 10 months. With a median follow up of 37 months, 14 (64%) patients were alive and in remission, including 11 who had undergone alloHSCT. Four of the 6 patients who died had a complex karyotype. Median overall survival for the entire cohort was not reached (Figure). Conclusions: HyperCVAD results in high remission rates in patients with ALAL, with low incidence of early mortality and high ability to proceed to allogeneic transplantation following response. HyperCVAD can be considered an effective front-line therapy for patients with ALAL. Additionally, hyperCVAD may be a backbone for incorporation of novel immunotherapies and targeted therapies, which may improve results in patients with appropriate targets. Disclosures Sweet: Astellas: Consultancy; Agios: Consultancy; Novartis: Consultancy, Honoraria, Speakers Bureau; Novartis: Consultancy, Honoraria, Speakers Bureau; Jazz: Speakers Bureau; Celgene: Honoraria, Speakers Bureau; Agios: Consultancy; Celgene: Honoraria, Speakers Bureau; BMS: Honoraria; Phizer: Consultancy; Jazz: Speakers Bureau; Astellas: Consultancy; Phizer: Consultancy; BMS: Honoraria. Wang:Novartis: Speakers Bureau; Amgen: Consultancy; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz: Speakers Bureau; Novartis: Speakers Bureau; Jazz: Speakers Bureau; Amgen: Consultancy. Al-Kali:Novartis: Research Funding.

Abstract Background While unfavorable karyotype at referral is associated with significantly inferior overall and leukemia-free survival in myelofibrosis (MF) patients (Blood. 2011 Oct 27;118(17):4595), the incidence of clonal evolution during JAK inhibitor (JAKi) treatment and its clinical significance are not currently known. We conducted a sponsor-independent, single-center retrospective analysis examining the phenotypic correlates and prognostic impact of clonal evolution during JAKi treatment. Methods Clinical, cytogenetic and molecular data were collected on MF patients treated with one or more JAKi on a clinical trial at the Mayo Clinic, Rochester, MN. Baseline data pertained to the onset of treatment with first JAKi. Karyotype risk categories were as previously defined (Blood. 2011 Oct 27;118(17):4595). Serial bone marrow biopsies were obtained at varying frequencies based on individual JAKi protocol requirements. Mutation screening was performed as previously described (Leukemia. 2013 Apr 26. doi: 10.1038/leu.2013.119). Information on survival and leukemic transformation was updated in July 2013. Results A total of 157 MF patients were studied (60% male; median age 65 years, range 34-89 years). The DIPSS-plus distribution was: Low/Int-1 20 (13%), Int-2 66 (42%), and High 71 (45%). The first JAKi was momelotinib (CYT387) in 79 patients (50%), ruxolitinib in 51 (33%) and fedratinib (SAR302503) in 27 (17%). Median follow up from first JAKi treatment was 30 months (range 1-67 months); during this period, 72 deaths (46%) and 14 (9%) leukemic transformations were documented. Eighty nine patients (57%) had a median total 3 (range 2-8) bone marrow biopsies with karyotype analysis during JAKi treatment. Of these, 21 patients (24%) showed clonal evolution (ie, acquisition or loss of one or more chromosome abnormalities when comparing last observed karyotype during JAKi treatment to baseline). Overall, 13 patients (15%) had upstaging of karyotype risk category (eg, normal to unfavorable), 9 (10%) had downstaging (eg, favorable to normal) and 67 (75%) had no change. Acquisition of worse-than-baseline karyotype was significantly higher in DIPSS-plus high-risk patients (26%) versus non-high risk patients (6%) (p=0.03). There was no association between acquisition of a worse karyotype category and baseline karyotype risk category or ASXL1 or SRSF2 mutation status. There was borderline association with RBC transfusion-dependence and constitutional symptoms at baseline (p=0.06). There was no relationship between clonal evolution and achievement of spleen or anemia response during JAKi treatment (p>0.05). The median overall survival of the entire cohort was 41 months. On univariate analysis, overall survival was significantly worse in patients who acquired a worse-than-baseline karyotype risk category during JAKi treatment (n=13, 77% deaths, median survival=31 months) versus those who did not (n=76, 43% deaths, median survival=52 months) (p=0.01) (Figure). On multivariate analysis, the prognostic significance of acquiring a worse karyotype risk category was maintained against all individual DIPSS-plus prognostic variables, including baseline karyotype risk category, except age >65 years. On univariate analysis, leukemia-free survival was significantly worse in patients who acquired a worse-than-baseline karyotype risk category during JAKi treatment (n=13, 31% leukemic transformation, median leukemia-free survival=32 months) versus those who did not (n=76, 8% leukemic transformation, median leukemia-free survival not reached) (p=0.0006) (Figure). On multivariate analysis against known predictors of leukemic risk in PMF patients (ie, baseline unfavorable karyotype, SRSF1 mutated status and platelet count <100 x 109/L), only acquisition of a worse-than-baseline karyotype risk category maintained its prognostic value (HR 5.3, p=0.03) Conclusions This is the first study to examine the incidence of clonal evolution during JAKi treatment in MF patients. Approximately 25% of patients exhibited clonal evolution; acquisition of a worse-than-baseline karyotype risk category had a strong and independent association with inferior leukemia-free survival. A similar association was also observed for inferior overall survival, albeit not independent of older age. In contrast, there was no association with spleen or anemia response during JAKi treatment. Disclosures: Pardanani: Bristol Myers Squibb: Clinical trial support Other; Sanofi: Clinical trial support. Publication support service., Clinical trial support. Publication support service. Other; PharmaMar: Clinical trial support, Clinical trial support Other; JW Pharmaceutical Corp.: Clinical trial support, Clinical trial support Other.