Gangat, Naseema

7058 Background: The 2016 WHO classification includes myelodysplastic/myeloproliferative neoplasms, unclassifiable (MDS/MPN-U), as an MDS/MPN overlap syndrome not meeting criteria for well-defined entities such as CMML. No standard prognostication or treatment guidelines exist for such patients. Methods: We retrospectively identified MDS/MPN-U cases from 1990-2016 through our myeloid malignancies database. All bone marrow reports were reviewed to ensure compliance with 2016 WHO criteria. Clinical & cytogenetic parameters at diagnosis were assessed & compared with treatment outcomes. Results: Eighty nine patients met study criteria, with a median age of 69 years (range: 37-93); 58 (65%) males. Median follow-up was 22.2 months (range: 0-172), with 41 (46%) deaths & 13 (15%) leukemic transformations. Median OS was 24.8 months (range: 0-172). 43 (53%) patients had an abnormal karyotype, with common abnormalities being trisomy 8 (12%), complex karyotype (9%) & del (20q) (6%). Given the fewer types of abnormalities identified, the IPSS cytogenetic stratification was more effective than IPSS-R, with risk categorization including; 45 good (55%), 20 intermediate (25%) & 16 high risk (20%) respectively (8 unavailable). On univariate analysis, increased age (p = 0.05), decreased hemoglobin (p = 0.02), higher ANC (p = 0.03), circulating immature myeloid cells (p = 0.02), higher LDH (p = 0.009), absence of bone marrow ring sideroblasts (p = 0.001) & higher risk (intermediate & high) IPSS cytogenetic categories (p = 0.01) adversely impacted OS. In a multivariate model that included the aforementioned variables, higher risk IPSS cytogenetics retained a negative prognostic impact (p = 0.04). 28 patients received a median of 6 cycles (range: 1-21) of hypomethylating agent therapy (HMA), with an overall response rate of 18% (CR-3, PR-2). All responders had an abnormal karyotype (p = 0.01). However, HMA did not affect either OS or LFS. Conclusions: Intermediate & high risk IPSS cytogenetic categories independently & adversely impact survival in WHO defined MDS/MPN-U patients. HMA use did not impact OS; however, patients with abnormal karyotypes were more likely to respond.

AbstractBetween 1967 and 2017, 361 patients with myeloproliferative neoplasms (MPN), age ≤ 40 years, were seen at our institution, constituting 12% of all MPN patients (n = 3023) seen during the same time period; disease‐specific incidences were 12% in polycythemia vera (PV; n = 79), 20% in essential thrombocythemia (ET; n = 219) and 5% in primary myelofibrosis (PMF; n = 63). Compared to their older counterparts, younger patients were more likely to present with low risk disease (P < .001) and display female preponderance in ET (P = .04), lower incidence of arterial events overall (P < .001), and higher incidence of venous thrombosis in PV (P = .01). Younger patients were also more likely to express CALR mutations, in ET and PMF, normal karyotype, in PV and PMF, and lower incidence of high molecular risk mutations in PMF (P significant in all instances). Over median follow‐up of 11.3, 13, and 7.1 years for PV, ET, and PMF, leukemic transformations were respectively documented in 4%, 2%, and 10% (P values 0.1‐0.9) while incidences of fibrotic progression in PV (22%) and ET (16%) were expectedly higher in young patients, because of their longer survival (P < .001). Median survival in young patients was 37 years for PV, 35 for ET and 20 for PMF; the corresponding values were 22, 22, and 8 years for ages 41‐60 years and 10, 11, and 3 years for ages >60 years (P < .001). Young MPN patients comprise a unique disease subset defined by an attenuated‐risk cytogenetic and mutational backdrop and conspicuously longer survival compared to their older counterparts, which requires assertion during patient counseling.

Abstract We examined the influence of mutations and karyotype on conventional treatment response, specifically hematological improvement in anemia, in primary myelodysplastic syndromes (MDS). Cytogenetic and next generation sequencing (NGS)‐derived mutation information was available in 357 patients (median age 74 years; 70% males); the revised international prognostic scoring system risk distribution was very high in 11%, high 15%, intermediate 17%, low 40% and very low 16%. At least one mutation was detected in 81% of patients; most frequent were SF3B1 (32%), ASXL1 (27%), TET2 (24%) and U2AF1 (15%). At median follow‐up of 24 months, treatment with hypomethylating agents (HMAs) was documented in 121 (34%) patients, lenalidomide (LEN) in 55 (15%), and erythropoiesis stimulating agents (ESAs) in 136 (38%). ASXL1 mutations adversely affected response to HMAs (27% vs 48%; P = 0.02) and LEN (9% vs 43%; P = 0.04), but not ESAs ( P = 0.6). LEN response was also adversely affected by U2AF1 mutations (0% vs 42%; P = 0.02) and high risk karyotype (0% vs 41% in intermediate vs 47% in low risk; P = 0.01). Patients with SF3B1 mutations were more likely to respond to LEN (56% vs 27%; P = 0.04). Contrary to previous reports, we found no association between TET2 mutations and HMA treatment response (40% vs 41%; P = 0.9), even in the absence of ASXL1 mutations ( P = 0.4).We conclude that ASXL1 mutations in MDS predict inferior response to treatment with both HMAs and LEN; response to LEN was also compromised by U2AF1 mutations and high risk karyotype; SF3B1 mutations identified patients likely to respond to LEN.

AbstractIn a 28‐year period, 39 (7%) patients with chronic myelomonocytic leukemia (CMML) (median age 66 years, 64% male) underwent a splenectomy at our institution. Primary indications for splenectomy were refractory thrombocytopenia (36%), progressive spleen related symptoms (33%), emergent splenectomy for splenic rupture (21%), refractory anemia (8%), and prior to allogeneic stem cell transplant (3%). Eleven (28%) patients had anemia at the time of splenectomy, of which 3 (27%) were autoimmune. The median time to splenectomy from CMML diagnosis was 6 months (0‐40); perioperative morbidity and mortality rates were 43% and 13%, while the median postsplenectomy survival was 25 months (11‐38). Durable remission in spleen related symptoms, thrombocytopenia, complications from splenic rupture, and anemia were achieved in 85%, 50%, 62%, and 21% of patients, respectively. Perioperative morbidity (n = 30) included infections/sepsis in 6 (20%), intraabdominal bleeding in 4 (13%), venous thromboembolism (VTE) in 3 (10%), and acute lung injury in 2 (7%) patients. The median duration of hospital stay was 6 days (1‐25), with 5 deaths occurring secondary to respiratory failure (n = 2), multiorgan dysfunction (n = 2) and hemorrhagic shock (n = 1). There was no difference in overall survival between CMML patients that underwent splenectomy, in comparison to those that did not. Unlike in myelofibrosis, portal hypertension was not an indication for splenectomy and no patients developed post‐splenectomy thrombocytosis. In conclusion, apart from being a lifesaving emergent modality in the event of splenic rupture, splenectomy has an important palliative role in patients with CMML, with significant and durable improvements in spleen related symptoms and refractory cytopenias.