Pardanani, Animesh

6614 Background: CDKN2A locus on chromosome 9p21 is implicated in altered molecular pathways leading to leukemogenesis as a tumor suppressor by inhibiting the proliferative kinases CDK4/CDK6 and blocking the cell-cycle division during G1/S phase. Deletion of CDKN2A locus is frequently seen in ALL, although prognostic significance remains unclear. Methods: Retrospective chart review at Mayo Clinic between 8/2005-11/2011 was performed on adult B-ALL patients (pts) who underwent fluorescent in situ hybridization (FISH) studies at diagnosis. Survival estimate was calculated using Kaplan-Meier statistics. Event-free survival (EFS) was defined as time between diagnosis and induction failure, relapse, or death, while overall survival (OS) as time between diagnosis and death Results: Out of 27 pts who had FISH studies for CDKN2A, 15 (56%) pts had CDKN2A deletions (8 homozygous/7 hemizygous), while 12 (44%) pts had diploid cytogenetics (none had abnormalities of MLL, bcr/abl fusion or CDKN2A deletion on FISH). There was no significant difference in median age, gender, WBC, hemoglobin, platelet count, LDH or complete remission (CR) rate (p=0.924) between the two groups. CDKN2A-deleted pts had higher circulating blasts (34% vs 16%, p=0.017). Of 13 CDKN2A-deleted pts, chromosome 9p was intact in 9 (69%) pts using routine cytogenetics. In the CDKN2A-deleted group, allogeneic stem cell transplant (ASCT) was performed in 7 (47%) pts at first CR and 1 at second CR. Four of 15 (27%) CDKN2A-deleted pts also had bcr/abl fusion. Five-year EFS was poorer in CDKN2A-deleted pts compared to normal FISH group (22% vs 60%, p=0.042), while 5-year OS was 72% vs 60% (p=0.308), respectively. Excluding the 4 bcr/abl fusion pts, 5-year EFS was still statistically significant (p=0.008). In the CDKN2A deleted group, both 5-yr EFS (80% vs 0%, p=0.006) and OS (100% vs 42%, p=0.016) were significantly superior in pts who received ASCT. Conclusions: CDKN2A deletions predict earlier relapse in pts with B-ALL. Majority of 9p abnormalities were only found by FISH testing and missed by conventional cytogenetics. In CDKN2A deleted pts, ASCT gave overall survival advantage. Further investigation through larger cohorts of pts is needed to validate these findings.

7110 Background: Abnormal cytokine expression may represent an inflammatory response that contributes to the clinical phenotype of MF. Some constitutional symptoms (eg. fever, fatigue, pruritus, cachexia) are thought to be caused by elevated cytokines. In phase I/II studies, SAR302503 reduced splenomegaly and constitutional symptoms in patients with MF. Here, we report the effects of SAR302503 on the expression of 97 cytokines in MF patients enrolled in a Phase II study (NCT01420770) and the relationship to clinical response (spleen size), pharmacokinetic (PK) exposure, and body weight changes. Methods: Thirty-one patients were randomized to receive 300, 400, or 500 mg of SAR302503 orally, once daily, continuously in 4-week cycles. Plasma cytokines were measured at baseline and at the end of 4, 8, and 12 weeks of treatment using a microsphere-based immuno-multiplex assay (Rules Based Medicine). Results: Complete sample sets were available for 29/31 patients. A total of 28 cytokines predominantly involved in immune/inflammation pathways were regulated ≥1.5-fold (ANOVA P<0.05) and of these, 19 were regulated at all time points, indicating rapid and sustained modulation by JAK2 inhibition. At 4 weeks, 16 cytokines were down-regulated, including TNFα, IL-1RA, and IL-18, and 6 were up-regulated, including leptin, EPO, and adiponectin. Hierarchical clustering of the 22 regulated cytokines enriched patients into spleen responder (≥35% reduction in spleen volume by MRI) and non-responder groups, suggesting a link between cytokine modulation and clinical response. Moderate correlations (P<0.05) with spleen volume reduction at the end of week 12 were seen for a subset of regulated cytokines, including adiponectin and TNFα. Levels of the majority of the regulated cytokines tended to correlate with steady state PK exposure at week 4. A positive association with weight changes at week 24 were observed for leptin and adiponectin at week 4 (P<0.05). Conclusions: This analysis shows that SAR302503 treatment modulated the expression of circulating cytokines in MF patients in association with changes in clinical activity, PK exposure, and symptom improvement (weight gain). Clinical trial information: NCT01420770.

7030 Background: JAK2V617F occurs in approximately 50% of patients with essential thrombocythemia. Qualitative studies of mutation analysis have previously reported an association between JAK2V617F and advanced age, higher hemoglobin level, higher leukocyte count, and lower platelet count. A possible association with thrombotic complication has also been considered. Methods: Allele-specific, quantitative PCR analysis for JAK2V617F was performed on 176 patients with ET, using genomic DNA from archived bone marrow, which was collected within one year (n=72), between 1 and 5 years (n=64), or after 5 years (n=40) of diagnosis. Results: JAK2V617F was detected in 96 patients (55%), in whom mutant allele burden ranged from 1% to 100% (median 6.3%). Neither mutational frequency (p=0.37) nor mutant allele burden (p=0.62) was affected by the timing of bone marrow sample collection. Presence of JAK2V617F was significantly associated with higher hemoglobin level (p<0.0001), lower platelet count (p=0.001), higher leukocyte count (p=0.008), increased incidence of venous thrombosis occurring after diagnosis (p=0.02), and older age at diagnosis (p=0.03). All but age retained significance in multivariable analysis. In mutation-positive patients (n=96), JAK2V617F allele burden clustered between 1% and 22% in 94 cases, in whom it correlated directly and significantly with platelet and leukocyte counts, palpable splenomegaly at diagnosis, and venous thrombosis occurring after diagnosis. Conclusions: JAK2V617F allele burden imparts additional phenotypic effects in ET. No significant financial relationships to disclose.

7029 Background: A leukocyte count of > 15 ×109/L has recently been associated with myocardial infarction in polycythemia vera (PV). In the current study, we examine the impact of such degree of leukocytosis on survival, leukemic transformation (LT), and thrombosis in a large cohort of PV patients from a single institution Methods: Data was abstracted from the medical records of a consecutive cohort of patients with PV defined by the World Health Organization criteria. Results: i. Patient characteristics The study cohort included 459 patients (median age, 60 years). Median follow-up was 64 months. ii. Survival In a multivariable analysis, advanced age, leukocyte count of = 15 × 109/L, and arterial thrombosis at diagnosis were significantly associated with inferior survival. A prognostic model based on age = 60 years and leukocyte count = 15 × 109/L separated low-risk, intermediate-risk, and high-risk patient groups with respective median survivals of 272, 162, and 108 months (p<0.0001). iii. Leukemic transformation In a multivariable analysis, only leukocyte count was significantly associated with LT; median leukemia-free survival for patients with leukocyte count = 15 × 109/L was 273 months vs. not reached for those with lower leukocyte count (p<0.0001). iv. Thrombosis at diagnosis In multivariable analysis, arterial thrombosis at diagnosis was significantly associated with previous history of arterial thrombosis, hypertension, and tobacco use; venous thrombosis at diagnosis was significantly associated with previous venous event and splenomegaly. v. Thrombosis during follow- up In multivariable analysis, arterial thrombosis during follow-up was significantly associated with previous arterial event, hypertension, and tobacco use; venous thrombosis during follow-up was significantly associated with previous venous event, diabetes mellitus, advanced age, and leukocyte count = 1,500 × 109/L. Conclusions: The current study for the first time identifies leukocytosis as a risk factor for inferior survival, LT risk, and venous thrombosis in PV. No significant financial relationships to disclose.

Background Patients with myelofibrosis (MF) who fail or are intolerant to JAK inhibitors (JAKi) have limited treatment options. Tagraxofusp is a targeted therapy directed to CD123 that was approved by the FDA for the treatment of patients with blastic plasmacytoid dendritic cell neoplasm (BPDCN). CD123 is expressed on a variety of malignancies including BPDCN, acute myeloid leukemia (AML), and certain myeloproliferative neoplasms (MPN), including MF. High-expressing CD123+ plasmacytoid dendritic cells (pDCs), the cell of origin of BPDCN, have been detected in the microenvironment of certain myeloid neoplasms, including MF, where they may play a tumor-promoting role. Notably, pDCs share a common precursor cell with monocytes, and monocytosis has been reported as a poor prognostic factor in patients with MF, associated with shortened overall survival. We hypothesized that tagraxofusp may offer a novel and rational therapeutic approach in patients with relapsed/refractory MF, and in particular in patients with monocytosis. Aims To assess safety and evaluate efficacy of tagraxofusp in patients with MF who were relapsed, refractory, or unable to tolerate JAKi. Methods This multicenter, open-label Phase 1/2 trial is enrolling patients with MF. In the Stage 1 (dose escalation), tagraxofusp was administered as a daily IV infusion at 7, 9, or 12 mcg/kg on days 1-3 every 21 days (cycle 1-4), 28 days (cycles 5-7), and 42 days (cycles 8+). In Stage 2 (expansion), patients are receiving the recommended Phase 2 dose (12 mcg/kg). Results 27 patients with MF have been treated, including 14 patients who had previously received ≥ 3 lines of therapy. Median age was 69 years (range 54-81), 52% were female, and 26% had baseline monocytosis (≥ 1x109/L). Baseline risk assessment based on the DIPSS Plus risk group assessment showed 1 patient (4%) with intermediate-1, 16 patients (59%) with intermediate-2, and 9 patients (33%) with high-risk. At study entry, median platelet count was 59 K/uL; 67% of patients had baseline platelets &lt;100 K/uL, of which 10 patients had platelets &lt;50 K/uL. 74% of patients had baseline splenomegaly (spleen palpable ≥ 5 cm below the left costal margin). In terms of molecular mutations: JAK2 (n=18); CALR (n=3); and MPL (n=1), and additional molecular analysis showed ASXL1 (n=5). In terms of cytogenetics, 30% (8/27) of patients had an abnormal karyotype, mainly 20q- (n=3), -5/5q-, -7/7q-, and 12p- (each n=2). Most common treatment-related adverse events (TRAEs, incidence ≥ 15%) include headache, hypoalbuminemia, increased levels of alanine aminotransferase, thrombocytopenia, and anemia. Most common ≥ grade 3 TRAE's were thrombocytopenia (8%) and anemia (15%). Capillary leak syndrome was reported in 1 patient (grade 3). Among the 17 evaluable patients with baseline splenomegaly, 53% had spleen size reductions, of which 4 patients had reductions of &gt; 45%. In 5 patients with baseline splenomegaly and monocytosis (&gt;1x109/L monocytes), 80% (4/5) had spleen size reductions, of which 2 had reductions of &gt;45%. Five patients had treatment duration of 12 months or more, with two of those patients ongoing (13+,and 24+ months, respectively). Six patients with platelets &lt;100 K/uL had treatment duration of 6 months or more, including 3 patients with baseline monocytosis who had treatment duration of 12 months or more. 7 patients had objective responses (IWG-MRT 2013 responses), including Clinical improvement (CI) (n=5) and CI (Symptom) (n=2). 20 patients were evaluable for symptomatic assessment (MPN-SAF TSS). Symptom response rate was 45% (defined as ³50% reduction in TSS score). Reductions in both symptom score and spleen size was noted in 6/6 patients who had splenomegaly at baseline. Conclusions Tagraxofusp demonstrated single agent clinical activity, with a predictable and manageable safety profile, in patients with relapsed/refractory MF, including in patients with monocytosis, a poor prognostic factor and unmet medical need. Tagraxofusp may offer MF patients, and MF patients with monocytosis in particular, a novel treatment option. Enrollment continues, and updated trial data will be presented. This clinical trial is registered at clinicaltrials.gov: NCT02268253. Disclosures Pemmaraju: affymetrix: Research Funding; sagerstrong: Research Funding; Daiichi-Sankyo: Research Funding; plexxikon: Research Funding; novartis: Consultancy, Research Funding; Stemline Therapeutics: Consultancy, Honoraria, Research Funding; cellectis: Research Funding; celgene: Consultancy, Honoraria; samus: Research Funding; mustangbio: Consultancy, Research Funding; abbvie: Consultancy, Honoraria, Research Funding; incyte: Consultancy, Research Funding. Gupta:Sierra Oncology: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Honoraria, Research Funding. Yacoub:Dynavax: Equity Ownership; Cara: Equity Ownership; Ardelyx: Equity Ownership; Incyte: Consultancy, Honoraria, Speakers Bureau; Seattle Genetics: Honoraria, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Agios: Speakers Bureau; Hylapharm: Equity Ownership. Wang:Agios: Other: Advisory role; Amgen: Other: Advisory role; Daiichi: Other: Advisory role; Stemline: Other: Advisory role, Speakers Bureau; Pfizer: Other: Advisory role, Speakers Bureau; celyad: Other: Advisory role; Abbvie: Other: Advisory role; Kite: Other: Advisory role; Jazz: Other: Advisory role; Astellas: Other: Advisory role, Speakers Bureau. Lee:AstraZeneca Pharmaceuticals: Consultancy; Ai Therapeutics: Research Funding; Karyopharm Therapeutics: Consultancy; Roche Molecular Systems: Consultancy; Jazz Pharmaceuticals, Inc: Consultancy; Helsinn: Consultancy. Schiller:Agios: Research Funding, Speakers Bureau; Karyopharm: Research Funding; Onconova: Research Funding; Novartis: Research Funding; Pfizer Pharmaceuticals: Equity Ownership, Research Funding; Sangamo Therapeutics: Research Funding; Amgen: Other, Research Funding; Astellas: Research Funding; Biomed Valley Discoveries: Research Funding; Bristol Myer Squibb: Research Funding; Celgene: Research Funding, Speakers Bureau; Constellation Pharmaceutical: Research Funding; Daiichi Sankyo: Research Funding; Eli Lilly and Company: Research Funding; FujiFilm: Research Funding; Genzyme: Research Funding; Gilead: Research Funding; Incyte: Research Funding; J&J: Research Funding; Jazz Pharmaceuticals: Honoraria, Research Funding. Sardone:Stemline Therapeutics: Employment, Equity Ownership. Wysowskyj:Stemline Therapeutics: Employment, Equity Ownership. Chen:Stemline Therapeutics: Employment, Equity Ownership. Brooks:Stemline Therapeutics: Employment, Equity Ownership, Patents & Royalties. Poradosu:Stemline Therapeutics: Employment, Equity Ownership, Patents & Royalties. McDonald:Stemline Therapeutics: Employment, Equity Ownership. Rupprecht:Stemline Therapeutics: Employment, Equity Ownership. Talpaz:Imago BioSciences: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; CTI BioPharma: Research Funding; Constellation: Research Funding; Incyte: Research Funding; Novartis: Research Funding; Samus Therapeutics: Research Funding. Taparia:Novartis: Consultancy. Verstovsek:Protaganist Therapeutics: Research Funding; Ital Pharma: Research Funding; Astrazeneca: Research Funding; Pharma Essentia: Research Funding; Sierra Oncology: Research Funding; Novartis: Consultancy, Research Funding; Blueprint Medicines Corp: Research Funding; Incyte: Research Funding; Roche: Research Funding; NS Pharma: Research Funding; Celgene: Consultancy, Research Funding; Gilead: Research Funding; Promedior: Research Funding; CTI BioPharma Corp: Research Funding; Genetech: Research Funding; Constellation: Consultancy; Pragmatist: Consultancy. Khoury:Kiromic: Research Funding; Angle: Research Funding; Stemline Therapeutics: Research Funding. Patnaik:Stem Line Pharmaceuticals.: Membership on an entity's Board of Directors or advisory committees.

Summary Survival prediction in essential thrombocythaemia (ET) and polycythaemia vera (PV) is currently based on clinically‐derived variables; we examined the possibility of integrating genetic information for predicting survival. To this end, 906 molecularly‐annotated patients (416 Mayo Clinic; 490 University of Florence, Italy), including 502 ET and 404 PV, were recruited. Multivariable analysis identified spliceosome mutations to adversely affect overall ( SF3B1 , SRSF2 in ET and SRSF2 in PV) and myelofibrosis‐free ( U2AF1 , SF3B1 in ET) survival; TP53 mutations predicted leukaemic transformation in ET; “adverse” mutations occurred in 51 (10%) ET and 8 (2%) PV patients. We confirmed the independent survival effect of adverse mutations [hazard ratio (HR) 2·4, 95% CI 1·6–3·5], age >60 years (6·6, 4·6–9·7), male sex (1·8, 1·3–2·4) and leukocytosis ≥11 × 10 9 /l (1·6, 1·1–2·2), in ET, and adverse mutations (7·8, 3·1–17·0), age >67 years (5·4, 3·6–8·1), leukocytosis ≥15 × 10 9 /l (2·8, 1·8–4·2) and thrombosis history (2·0, 1·4–2·9), in PV. HR‐based risk point allocation allowed development of three‐tiered mutation‐enhanced international prognostic systems (MIPSS) which were validated in both cohorts and performance was shown to be superior to conventional scoring systems. Spliceosome mutations enhance survival prediction in ET and PV and identify patients at risk for fibrotic progression. TP53 mutations predict leukaemic transformation in ET.