Patnaik, Mrinal M.

e19538 Background: Chronic neutrophilic leukemia (CNL) is a rare and aggressive myeloproliferative neoplasm with poor survival. No standard of care exists. Case reports describe allogeneic stem cell transplantation (ASCT) as the only curative therapy. Using the National Cancer Database (NCDB), we studied prognostic factors and survival outcomes of CNL. Methods: Patients diagnosed in 2004-2015 were included. 9963/3 was the ICD-O-3 code. Overall survival (OS) was analyzed using the Kaplan-Meier method. Hazard ratios (HR) with confidence intervals (CI) were calculated using Cox proportional hazards model. Variables significant in univariate analysis were included in a multivariate analysis. Data on incidence was obtained from the Surveillance, Epidemiology, and End Results Program (SEER) 21 Registries (2004-2015). The analysis was done with SEER*Stat software. Incidence was age-adjusted to the U.S. 2000 standard population. Results: A total of 121 CNL patients were in NCDB. The median age at diagnosis was 70 years (range 21-90); 74 (61%) were males and 107 (88%) were ≥ 50 years. The median follow up time was 5.8 years (interquartile range [IQR] 2.9-7.4). 32 (26%) had a Charlson Deyo score (CDS) > 1. 80 (70%) had government insurance, while 34 (30%) had private insurance. Median OS was 2.2 years (IQR 0.8-6.7). OS was 70% at 1 year, 29% at 5 years, and 11% at 10 years. The year of diagnosis was not associated with improved OS (HR: 0.95 (95% CI: 0.88-1.02), p =0.14). 71 (59%) patients received chemotherapy. The median time to chemotherapy from the day of diagnosis was 15 days (IQR 7-35). The OS of those who received chemotherapy was 71% at 1 year and 27% at 5 years versus 69% and 32% at 1- and 5- years for those who did not ( p= 0.38). 2 patients received ASCT (age 52 and 61 years) as initial therapy and both were alive at 5 years. Factors predicting inferior OS on univariate analysis were age ≥ 50 years at diagnosis ( p= 0.005), male ( p< 0.001), CDS > 1 ( p= 0.038), and government insurance ( p= 0.004). The table shows the multivariate (MV) analysis. The overall incidence of CNL was 0.1 cases/1,000,000 individuals and did not change significantly from 2004-2015. The incidences by male, female, White, Black, and American Indian/Alaska Native were also 0.1 cases/1,000,000 individuals. Conclusions: OS and incidence of CNL have not changed over the years. Age ≥ 50 years, male gender, and use of government insurance predicted inferior OS. [Table: see text]

8542 Background: Clonal hematopoiesis of indeterminate potential (CHIP) is defined by the presence of leukemia-associated somatic mutations in clonally expanded hematopoietic stem cells with a VAF of ≥2%. CHIP has been associated with myeloid malignancies and increased all cause mortality largely from atherovascular disease. The prevalence and impact of CHIP in patients with myeloma (MM) is yet to be defined. Aims: Evaluate the prevalence and significance of CHIP in 101 lenalidomide exposed patients with multiple myeloma. Methods: 101 MM patients, the majority exposed to > 2 years of lenalidomide (Len), with stored mononuclear blood samples were identified for Next Generation Sequencing (NGS) using a panel encompassing 42 gene mutations associated with CHIP. Electronic medical records were reviewed and outcomes of secondary malignancy, macrocytosis, thrombosis and mortality were extracted. Results: Thirty of 101patients were found to have CHIP with the most frequent mutations: DNMT3A (12%), TET2 (5%), and TP53 (4%). One third of patients with CHIP had > 1 mutation (37%). At 68 months median follow up over a quarter of patients experienced thrombosis (31%) and 13% developed subsequent malignancy/premalignant condition including myelodysplastic syndrome (3%). There was no significant difference in age, gender, duration of Len prior to NGS testing, thrombosis complication, or survival in those with versus without a CHIP mutation. At last F/U 30% had died, 25% remained on therapy, 27% were on maintenance therapy and 11% were on observation alone. Conclusions: CHIP mutations are common in plasma cell neoplasms, with 30% of patients in this study retrospectively found to have CHIP mutations by NGS testing. CHIP mutations have been associated with cardiovascular events and malignancy development, however no associations were identified in this small study. Limitations to this study include small sample size, retrospective nature and duration of follow up. Further study of this very common finding in MM patients regarding timing of development and subsequent impact of these mutations could help risk stratify and inform therapy selection. [Table: see text]

Abstract Introduction: Antiphospholipid antibody syndrome (APS) is characterized by arterial or venous thrombosis, and/or adverse obstetric outcomes in the presence of persistent antiphospholipid antibodies (APab). Between 2–10% of all patients with APS are reported to present solely with anti beta-2 glycoprotein 1 antibodies (b2GP1 abs) (ref 1). In 2006 the Sapporo criteria were revised to include b2GP1 abs to the panel of diagnostic tests. While presence of a lupus anticoagulant (LA) has been found to correlate well with occurrence of thromboses, the prognostic and predictive roles of b2GP1 abs and anticardiolipin antibodies (ACLA) need better definition. Previous studies suggest both the severity of the initial event and the risk for recurrent events is greater among patients demonstrating presence of more than one APab on laboratory testing (ref 2 and 3), but this aspect needs further confirmation. Objectives: To identify the spectrum of clinical thrombotic and obstetric manifestations associated with the different APab profiles; To determine the prevalence and clinical significance of the b2GP1 ab positive and ACLA/LA negative phenotype; and To evaluate the significance of IgM b2GP1 ab and IgM ACLA. Methods: Medical records of patients tested for all three antiphospholipid antibodies at the University of Minnesota Medical Center from Dec 2000 to Dec 2005 were reviewed. Patients that met the modified criteria for APS were included. IgG and IgM ACLA were measured using the Diamedix kit (VAX diagnostics) and IgG and IgM b2GP1 abs using the Inovalite kit (NOVA diagnostics). LA was determined using standard protocol. Results: Over the 5 year period, all three laboratory assays were obtained in 560 individuals, but only 76 (13.5%) patients who met both the clinical and laboratory criteria for APS were included in this study. Seven of the 76 patients (9.2%) had isolated, persistently positive b2GP1 abs. LA alone was present in 21 patients (27.6%). Twenty nine patients (38%) had all three APabs, and had a higher incidence of thrombosis at multiple sites at the time of diagnosis as well as increased rate of recurrent events, in comparison to those with two or less than two APab. Isolated ACLA was present in only 2 patients (2.6%). Interestingly, both IgM (47%) and IgG (50%) b2GP1 abs were associated with thrombosis, whereas only IgG ACLA was found to be associated with thrombosis. Conclusion: The presence of b2GP1 abs as the sole laboratory anomaly is uncommon, but is noted in patients with APS, thus warranting it’s testing at the time of clinical suspicion. Amongst the different antibody types LA seems to be the strongest predictor for thrombotic events and ACLA seems to have a weaker link, consistent with the results of previous studies (ref 4). The presence of all three AP antibodies does increase the risk for recurrent and multiple thromboses.

In this phase 1 trial, inhibition of granulocyte-macrophage colony-stimulating factor (GM-CSF) was associated with clinically meaningful responses in 5 of 15 patients with relapsed or refractory chronic myelomonocytic leukemia (CMML). Preliminary data suggest that this approach may be tractable in CMML bearing activating NRAS mutations.

e18549 Background: Many vitamin deficiencies can cause anemia. It is prudent prior to diagnosing a myeloid neoplasm, to check for vitamin deficiencies and correct them. Myelodysplastic syndromes with ring sideroblasts (MDS-RS) are associated with anemia. Pyridoxine (Vit B6) replacement may improve anemia found in sideroblastic anemia. The study was to determine how frequently Vit B6 was assessed, replaced and impact replacement had on outcomes in MDS-RS. Methods: Study subjects were from the Mayo Clinic Myelodysplastic syndrome (MDS) database which contains 1315 patients (pts). Appropriate IRB approval was obtained. Diagnosis of MDS and its sub-classification was done according to World Health Organization 2016 criteria. A response was any improvement in hemoglobin. Overall survival (OS) estimates were calculated using Kaplan-Meier curves and univariate and multivariate analysis was done using JMP software version 13. Results: Among 1315 pts with MDS, 161 pts had a diagnosis of MDS-RS. Median age was 73, and 55 (34%) pts were females. Thirty-nine (36%) pts had very low, 53 (50%) low, 9 (8%) intermediate, 3 (3%) high, and 2 (1%) had very high revised international prognostic score. The median white blood cell count was 5.4 x109, platelet count was 255 x109, and hemoglobin was 9.9 gm/dL. Five pts (3%) had a Vit B6 levels done; out of whom, 4 (80%) were not Vit B6 deficient. Among 42 (26%) pts who had Vit B6 replacement, 21 (50%) had no response, 4 (10%) had a response and 17 (40%) had unknown response. 103 (64%) of the pts were transfusion independent (TI). Overall survival in pts who are transfusion dependent was 68 months compared to 85 in pts who are TI (Wilcoxon P =.03). There was an improvement in OS in the group that had Vit B6 replacement compared to the group with no Vit B6 replacement (92 months vs 68 months, Wilcoxon P =.07). Response to Vit B6 replacement did not show OS benefit. Acute Leukemia transformation in Vit B6 replacement was 2% and 6% in pts. who did not have Vit B6 replacement (P= .4). Conclusions: Vit B6 was not checked often in MDS-RS pts. There was a borderline improvement in OS in Vit B6 replacement group (p= .07). Response did not affect OS. A larger prospective study is needed to study Vit B6 role in MDS-RS.

7059 Background: Patients with chronic myelomonocytic leukemia (CMML) have historically poor outcomes, with ~6-7 mos median OS in relapsed/refractory (r/r) setting. Splenomegaly is a poor prognostic factor and potential target in CMML. CD123 is detected on blasts, monocytes, and neoplastic microenvironmental plasmacytoid dendritic cell (pDC) infiltrates part of the CMML malignant clone (Solary, et al). Tagraxofusp, a novel CD123 targeted therapy, demonstrated high levels of activity in BPDCN, an aggressive hematologic malignancy derived from CD123-expressing pDCs, and is FDA approved in BPDCN. As such, tagraxofusp may offer a novel approach in CMML. Methods: Multicenter, 2-stage Ph1/2 enrolling patients (pts) with r/r CMML. Objectives: determine optimal dose, evaluate safety and efficacy. Stage 1 dose escalation: IV tagraxofusp (7, 9, and 12 mcg/kg/day) dosed on days 1-3 every 21 days (C1-4), 28 days (C5-7), and 42 days (C8+). Stage 2 (ongoing), pts receive optimal S1 dose (12 mcg/kg/day; no MTD). Results: 20 pts (12 CMML-1; 8 CMML-2) enrolled. 18 pts 2nd-line (2 pts in 1L), HMAs most common prior therapy. Median age 69 (43-80); 81% male. 11 (52%) had baseline splenomegaly (spleen palpable below left costal margin by physical exam) of 2-27 cm. Most common TRAEs: hypoalbuminaemia (35%), thrombocytopenia (35%), nausea (30%), vomiting (30%), and fatigue (20%). Most common ≥Gr3 TRAEs were thrombocytopenia (35%) and nausea (5%). Capillary leak syndrome in 3 pts (15%; all Gr1&2). 100% (10/10) of pts with splenomegaly had spleen response: 80% (8/10) had reductions ≥50% and 67% (4/6) with spleen size ≥5 cm had reductions ≥50%. 3 pts achieved bone marrow complete responses, including 1 pt bridged to SCT in remission. Conclusions: Tagraxofusp demonstrated single agent activity in CMML as 80% of pts showed ≥50% reduction in splenomegaly by palpation. Splenomegaly in CMML, as in myelofibrosis, is a major cause of morbidity and associated with poor prognosis and impaired QoL. Targeting splenomegaly in myeloid neoplasms with proliferative features may be an important therapeutic goal. Given CD123 expression on CMML blasts, monocytes, and malignant pDCs, tagraxofusp may offer a targeted approach, especially in pts with splenomegaly. Updated safety and efficacy data to be presented. Registrational trial planned. Clinical trial information: NCT02268253.

7058 Background: Patients with myelofibrosis (MF) who fail or are intolerant to JAK inhibitors (JAKi) have no standard treatment options. CD123 is expressed on a variety of malignancies, including MF. CD123+ plasmacytoid dendritic cells (pDCs), in the MPN microenvironment, including chronic myelomonocytic leukemia and MF, may be tumor-promoting. Monocytosis in MF associated with rapid disease progression and short survival, suggesting an accelerated disease phase. Notably, monocytes share a common precursor with CD123+ pDCs. Tagraxofusp, a novel CD123 targeted therapy, demonstrated high activity in patients with BPDCN, an aggressive hematologic malignancy derived from CD123+ pDCs, and is FDA approved in BPDCN. As such, tagraxofusp may offer a novel therapeutic approach in MF. Methods: Multicenter, 2-stage Ph 1/2 trial enrolling patients (pts) with MF relapsed, refractory, or intolerant to JAKi. Objectives: determine optimal dose, evaluate safety and efficacy. Stage 1 dose escalation: IV tagraxofusp (7, 9, and 12 mcg/kg/day) dosed daily days 1-3 every 21 days (C1-4), 28 days (C5-7), and 42 days (C8+). Stage 2 (ongoing): pts receive optimal S1 dose (12 mcg/kg/day; no MTD). Results: 23 r/r pts treated. Median age 69 (55-81); 57% female. DIPSS Plus: 4% INT-1, 55% INT-2, 41% high. Baseline platelets: median 59 K/uL (15-579); 70% (16/23) <100 K/uL, 8 pts <50 K/uL. 87% (20/23) baseline splenomegaly (palpable ≥5 cm below left costal margin by physical exam). Most common TRAEs: headache (22%), hypoalbuminaemia (22%), ALT incr. (17%) and thrombocytopenia (17%). Most common ≥Gr3 TRAE thrombocytopenia (2%). Capillary leak syndrome in 1 pt (4%; Gr3). 57% (8/14) of pts with baseline spleen ≥5cm BCM spleen responses: 43% (6/14) had ≥29% and 21% (3/14) had ≥45% reduction. 100% of pts with baseline spleen ≥5cm and monocytosis splenomegaly reductions: 80% (4/5) had ≥29% and 40% (2/5) had ≥45%. 6 pts (3 monocytosis pts and 5 pts platelets <100 K/uL) had 6 mos+ duration, 9 pts ongoing. Conclusions: Tagraxofusp demonstrated single agent activity (reduction in splenomegaly) and manageable safety in R/R MF, including pts with monocytosis, an unmet medical need. Given the presence of CD123+ pDCs, tagraxofusp may offer a novel targeted approach in MF. Updated data to be presented. Registrational designs are being evaluated. Clinical trial information: NCT02268253.

7053 Background: The revised International Prognostic Scoring System (IPSS-R) aids in prognosticating MDS. The percentage (%) of blasts in the bone marrow is one of the major determinants of the scoring system. The aspirate blast % is utilized as the standard of care, but there could be discrepancies in the blast % reported by the aspirate and the biopsy. We aim to study the possible use of bone marrow biopsy blasts in MDS-EB in calculating IPSS-R. Methods: The MDS database was reviewed for cases of MDS-EB after due IRB approval. We calculated IPSS-R scores based on the aspirate blast % (IPSS-RAsp) and biopsy blast % (IPSS-RBx). The biopsy blast % was reported morphologically or by the CD34 stain. Whenever a range was reported the highest value was utilized as the blast %. Suboptimal aspirates were excluded from the study. The overall survival (OS) was determined by IPSS-RAsp, IPSS-RBx and IPSS-R highest blast (IPSS-RHi). OS estimates were calculated by Kaplan-Meier curves and log-rank testing using JMP v.13. Uno’s concordance statistic was used to compare all 3 risk scoring systems. Results: Of 1322 patients, 431 (33%) cases were identified with MDS-EB; out of which 173 cases had both blasts reported in the biopsy and the aspirate. Out of 173 cases, 35 (20%) had MDS-EB1, and 61 (35%) had MDS EB-2 based on both biopsy and aspirate (concordant cases). Seventy seven (45%) patients changed from EB-1 to EB2 or vice versa based on the biopsy blast (44/77 (57%) cases were upstaged). The OS outcomes based on the IPSS-RBx biopsy showed a clear and meaningful separation with median OS decreasing with increased risk but IPSS-RAsp and IPSS-RHi did not (Table). We compared the 3 models for observed OS differences using the Uno model and there was no statistically significant difference. Conclusions: IPSS-RBx (but not IPSS-RAsp and IPSS-RHi) identified prognostic groups for OS with median OS decreasing with increased risk. The small sample size may have led to an insignificant effect on model power by Uno model. This finding needs to be validated by other centers. [Table: see text]