A Pilot Study of the Telomerase Inhibitor Imetelstat for Myelofibrosis.

BACKGROUND: Current drugs for myeloproliferative neoplasm-associated myelofibrosis, including Janus kinase (JAK) inhibitors, do not induce complete or partial remissions. Imetelstat is a 13-mer lipid-conjugated oligonucleotide that targets the RNA template of human telomerase reverse transcriptase. METHODS: We sought to obtain preliminary information on the therapeutic activity and safety of imetelstat in patients with high-risk or intermediate-2-risk myelofibrosis. Imetelstat was administered as a 2-hour intravenous infusion (starting dose, 9.4 mg per kilogram of body weight) every 1 to 3 weeks. The primary end point was the overall response rate, and the secondary end points were adverse events, spleen response, and independence from red-cell transfusions. RESULTS: A total of 33 patients (median age, 67 years) met the eligibility criteria; 48% had received prior JAK inhibitor therapy. A complete or partial remission occurred in 7 patients (21%), with a median duration of response of 18 months (range, 13 to 20+) for complete responses and 10 months (range, 7 to 10+) for partial responses. Bone marrow fibrosis was reversed in all 4 patients who had a complete response, and a molecular response occurred in 3 of the 4 patients. Response rates were 27% among patients with a JAK2 mutation versus 0% among those without a JAK2 mutation (P=0.30) and 32% among patients without an ASXL1 mutation versus 0% among those with an ASXL1 mutation (P=0.07). The rate of complete response was 38% among patients with a mutation in SF3B1 or U2AF1 versus 4% among patients without a mutation in these genes (P=0.04). Responses did not correlate with baseline telomere length. Treatment-related adverse events included grade 4 thrombocytopenia (in 18% of patients), grade 4 neutropenia (in 12%), grade 3 anemia (in 30%), and grade 1 or 2 elevation in levels of total bilirubin (in 12%), alkaline phosphatase (in 21%), and aspartate aminotransferase (in 27%). CONCLUSIONS: Imetelstat was found to be active in patients with myelofibrosis but also had the potential to cause clinically significant myelosuppression. (Funded by Geron; ClinicalTrials.gov number, NCT01731951.).

Long-term survival and blast transformation in molecularly annotated essential thrombocythemia, polycythemia vera, and myelofibrosis.

Janus kinase 2 (JAK2) mutations define polycythemia vera (PV). Calreticulin (CALR) and myeloproliferative leukemia virus oncogene (MPL) mutations are specific to JAK2-unmutated essential thrombocythemia (ET) and primary myelofibrosis (PMF). We examined the effect of these mutations on long-term disease outcome. One thousand five hundred eighty-one patients from the Mayo Clinic (n = 826) and Italy (n = 755) were studied. Fifty-eight percent of Mayo patients were followed until death; median survivals were 19.8 years in ET (n = 292), 13.5 PV (n = 267; hazard ratio [HR], 1.8; 95% confidence interval [CI], 1.4-2.2), and 5.9 PMF (n = 267; HR, 4.5; 95% CI, 3.5-5.7). The survival advantage of ET over PV was not affected by JAK2/CALR/MPL mutational status. Survival in ET was inferior to the age- and sex-matched US population (P < .001). In PMF (n = 428), but not in ET (n = 576), survival and blast transformation (BT) were significantly affected by mutational status; outcome was best in CALR-mutated and worst in triple-negative patients: median survival, 16 vs 2.3 years (HR, 5.1; 95% CI, 3.2-8.0) and BT, 6.5% vs 25% (HR, 7.6; 95% CI, 2.8-20.2), respectively. We conclude that life expectancy in morphologically defined ET is significantly reduced but remains superior to that of PV, regardless of mutational status. In PMF, JAK2/CALR/MPL mutational status is prognostically informative.

Next-generation sequencing in systemic mastocytosis: Derivation of a mutation-augmented clinical prognostic model for survival.

In routine practice, the World Health Organization classification of systemic mastocytosis (SM) is also the de facto prognostic system; a core value is distinguishing indolent (ISM) from advanced SM (includes aggressive SM [ASM], SM with associated hematological neoplasm [SM-AHN] and mast cell leukemia [MCL]). We sequenced 27 genes in 150 SM patients to identify mutations that could be integrated into a clinical-molecular prognostic model for survival. Forty four patients (29%) had ISM, 25 (17%) ASM, 80 (53%) SM-AHN and 1 (0.7%) MCL; overall KITD816V prevalence was 75%. In 87 patients, 148 non-KIT mutations were detected; the most frequently mutated genes were TET2 (29%), ASXL1 (17%), and CBL (11%), with significantly higher mutation frequency in SM-AHN > ASM > ISM (P < 0.0001). In advanced SM, ASXL1 and RUNX1 mutations were associated with inferior survival. In multivariate analysis, age > 60 years (HR = 2.4), hemoglobin < 10 g/dL or transfusion-dependence (HR = 1.7), platelet count < 150 × 10(9) /L (HR = 3.2), serum albumin < 3.5 g/dL (HR = 2.6), and ASXL1 mutation (HR = 2.3) were associated with inferior survival. A mutation-augmented prognostic scoring system (MAPSS) based on these parameters stratified advanced SM patients into high-, intermediate-, and low-risk groups with median survival of 5, 21 and 86 months, respectively (P < 0.0001). These data should optimize risk-stratification and treatment selection for advanced SM patients. Am. J. Hematol. 91:888-893, 2016. © 2016 Wiley Periodicals, Inc.

A compendium of cytogenetic abnormalities in myelofibrosis: molecular and phenotypic correlates in 826 patients.

Among 826 patients with primary myelofibrosis (PMF) and analysable metaphases on cytogenetic studies, 352 (42·6%) had abnormal karyotype, of which 240 (68·2%) were sole aberrations and 48 (13·6%) were complex; the most frequent abnormalities were 20q- (23·3%), 13q- (18·2%), +8 (11·1%), +9 (9·9%), chromosome 1q+ (9·7%) and -7/7q- (7·1%). Phenotypic correlates included: abnormal karyotype with anaemia (P = 0·02), leucopenia (P < 0·01) and thrombocytopenia (P < 0·01); complex karyotype with younger age (P = 0·04) and thrombocytopenia (P < 0·01); leucopenia with 20q-, +8 and -7/7q- and thrombocytopenia with 20q- and -7/7q-. Cytopenias were less likely to occur with 13q-. 476 patients were annotated for JAK2/CALR/MPL mutations; abnormal karyotype frequencies were 43% in JAK2, 42% CALR, 33% MPL mutated and 34% triple-negative cases (P = 0·3). A proportion of patients were also screened for ASXL1, EZH2, IDH1, IDH2, SRSF2, U2AF1 and SF3B1 mutations; in all instances, mutational frequencies were higher in patients with normal karyotype, reaching significance for ASXL1 (P = 0·02) and U2AF1 (P = 0·01). 13q- was associated with mutant CALR (P = 0·03), +9 with mutant JAK2 (P = 0·02) and 20q- with mutant SRSF2 (P = 0·02). The current PMF study provides detailed cytogenetic information and correlations with mutations and clinical phenotype.

Mutations and thrombosis in essential thrombocythemia: prognostic interaction with age and thrombosis history.

BACKGROUND: Vascular events in essential thrombocythemia (ET) are associated with advanced age and thrombosis history. Recent information suggests additional effect from the presence of specific mutations. OBJECTIVES: To examine the influence of age and thrombosis history on the reported association between mutational status and thrombosis-free survival in ET. PATIENTS AND METHODS: Analysis was performed using a Mayo Clinic cohort of 300 ET patients, and key findings were reanalyzed by including additional 102 Italian patients. RESULTS: Among 300 Mayo patients with ET (median age 55 yr, 60% females), mutational frequencies were 53% JAK2, 32% CALR, 3% MPL, and 12% JAK2, CALR and MPL wild type. One hundred and six (35%) patients experienced arterial (n = 75) or venous (n = 43) events, before (n = 55) or after (n = 71) diagnosis. In univariate analysis, compared to JAK2-mutated cases, JAK2, CALR and MPL wild type (HR 0.31, 95% CI 0.11-0.86), and CALR-mutated (0.53, 95% CI 0.30-0.92) patients displayed better thrombosis-free survival. JAK2, CALR, and MPL wild type remained significant (P = 0.03; HR 0.32, 95% CI 0.11-0.9) during multivariable analysis that included age (P = 0.01) and thrombosis history (P = 0.0006); a favorable impact from CALR mutations was of borderline significance (P = 0.1; HR 0.62, 95% CI 0.35-1.1), but became significant (P = 0.02) when multivariable analysis including thrombosis history (P = 0.02) was performed on patients younger than 60 yr of age. CONCLUSIONS: The favorable impact of mutational status on thrombosis-free survival in ET might be most evident for JAK2, CALR, and MPL wild type patients, whereas the favorable effect from CALR mutations might be confined to young patients.

Blast transformation in chronic myelomonocytic leukemia: Risk factors, genetic features, survival, and treatment outcome.

Among 274 patients with chronic myelomonocytic leukemia (CMML) and followed for a median of 17.1 months, blast transformation (BT) occurred in 36 (13%). On multivariable analysis, risk factors for BT were presence of circulating blasts (HR 5.7; 95% CI 2.8-11.9) and female gender (HR 2.6; 95% CI 1.3-5.1); the results remained unchanged when analysis was restricted to CMML-1. ASXL1/SRSF2/SF3B1/U2AF1/SETBP1 mutational frequencies were not significantly different between time of CMML diagnosis and BT. Median survival post-BT was 4.7 months (5-year survival 6%) and better with allogeneic stem cell transplant (SCT) (14.3 months vs. 4.3 months for chemotherapy vs. 0.9 months for supportive care; P = 0.03). Neither karyotype nor mutational status was independently associated with risk of BT or post-BT survival. We conclude that female patients with CMML and those with circulating blasts are at a higher risk of BT. Post-BT survival is dismal and our observations suggest consideration of allogeneic SCT prior to BT.

Molecular and prognostic correlates of cytogenetic abnormalities in chronic myelomonocytic leukemia: a Mayo Clinic-French Consortium Study.

Four hundred and nine patients with chronic myelomonocytic leukemia (CMML) were included in the international collaborative study (268 (66%) and 141 (34%) from Mayo clinic and French consortium respectively). Thirty percent displayed an abnormal karyotype, including; 72% sole, 16% two, and 11% complex abnormalities. The most common abnormalities included; +8 (23%), -Y (20%), -7/7q-(14%), 20q- (8%), +21 (8%), and der(3q) (8%). Patients with an abnormal karyotype were more likely to be elderly (P = 0.03), be anemic (P = 0.0009), have leukocytosis (P = 0.02) with neutrophilia (P = 0.03), demonstrate increased circulating immature myeloid cells (P = 0.0003), peripheral blood blasts (P < 0.0001), and bone marrow blasts (P < 0.0001). ASXL1 (P = 0.04) and SF3B1 (P = 0.03) mutations clustered with an abnormal karyotype, whereas SRSF2 (P = 0.02) mutations occurred more commonly with a normal karyotype. A step-wise survival analysis resulted in three distinct cytogenetic risk categories: high (complex and monosomal karyotypes), intermediate (all abnormalities not in the high or low risk groups) and low [normal, sole -Y and sole der (3q)] with median survivals of 3 [hazard ratio (HR) = 8.1, 95% confidence interval (CI) = 4.6-14.2], 20 (HR = 1.7, 95% CI = 1.2-2.3) and 41 months, respectively. In multivariable analysis, this particular cytogenetic risk stratification remained significant in the context of the Molecular Mayo Model (P < 0.0001), MD Anderson prognostic model (P < 0.0001), the GFM CMML model (P < 0.0001) and was effective in predicting leukemic transformation (P = 0.004).

Type 1 versus Type 2 calreticulin mutations in essential thrombocythemia: a collaborative study of 1027 patients.

CALR (calreticulin) trails JAK2 as the second most mutated gene in essential thrombocythemia (ET). Mutant CALR in ET is a result of frameshift mutations, caused by exon 9 deletions or insertions; type-1, 52-bp deletion (p.L367fs*46), and type-2, 5-bp TTGTC insertion (p.K385fs*47) variants constitute more than 80% of these mutations. The current study includes a total of 1027 patients divided into test (n = 402) and validation (n = 625) cohorts. Among the 402 ET patients in the test cohort, 227 (57%) harbored JAK2, 11 (3%) Myeloproliferative leukemia virus oncogene (MPL), and 114 (28%) CALR mutations; 12% were wild-type for all three mutations (i.e., triple-negative). Among the 114 patients with CALR mutations, 51 (45%) displayed type-1 and 44 (39%) type-2 variants; compared to mutant JAK2, both variants were associated with higher platelet and lower hemoglobin and leukocyte counts. However, male sex was associated with only type-1 (P = 0.005) and younger age with type-2 (P = 0.001) variants. Notably, platelet count was significantly higher in type-2 vs. type-1 CALR-mutated patients (P = 0.03) and the particular observation was validated in the validation cohort that included 111 CALR-mutated ET patients (P = 0.002). These findings, coupled with the recent demonstration of preferential expression of mutant and wild-type CALR in megakaryocytes, suggest differential effects of CALR variants on thrombopoiesis.

Checkpoint inhibitors: the new treatment paradigm for urothelial bladder cancer.

Bladder cancer is the most common malignancy involving the genitourinary system (Siegel et al. in CA Cancer J Clin, 66:7-30, 2016). In the USA, it is the fifth most common cancer and approximately 79,000 new cases will be diagnosed in 2017 (Siegel et al. in CA Cancer J Clin, 66:7-30, 2016). The mortality from bladder cancer is approximately 17,000 deaths each year (Siegel et al. in CA Cancer J Clin, 66:7-30, 2016). The incidence rate for bladder cancer is higher in men compared to women. Risk factors are predominantly related to tobacco smoking, although infection with Schistosoma haematobium is another risk factor in selected populations (Antoni et al. in Eur Urol, 71:96-108, 2017). Cisplatin-based systemic chemotherapy regimens remain the standard of care in both the neoadjuvant and metastatic setting for muscle-invasive bladder cancer (Gupta et al. in Cancer, 9(15):1-14, 2017; Von der Maase et al. in J Clin Oncol, 23:4602-4608, 2005; De Santis et al. in J Clin Oncol, 30:191-199, 2012; Bellmunt et al. in J Clin Oncol, 27: 4454-4461, 2009). There is an estimated overall survival of 9-15 months in metastatic bladder cancer in those who receive the standard of care platinum-based chemotherapy (Von der Maase et al. in J Clin Oncol, 23:4602-4608, 2005; De Santis et al. in J Clin Oncol, 30:191-199, 2012). The median survival, however, is significantly reduced after relapse in patient treated with platinum chemotherapy to less than 7 months (Bellmunt et al. in J Clin Oncol, 27: 4454-4461, 2009). Thus, this approach is preferred for patients who can tolerate this treatment as first-line chemotherapy (Gupta et al. in Cancer, 9(15):1-14, 2017). Until recently, there were few treatment options for those patients with poor performance status who are ineligible to receive cisplatin including renal insufficiency and multiple comorbidities or had disease progression after receiving platinum-based chemotherapy (Gupta et al. in Cancer, 9(15):1-14, 2017). With further understanding of tumor immune evasion, systemic immunotherapy which utilizes the patient's own immune system directly to eradicate and target neoplastic cells, has now been approved for urothelial bladder cancer. Monoclonal antibodies that target programmed cell death protein 1 (PD-1), including Nivolumab and Pembrolizumab, and its ligand, PD-L1, including Atezolizumab, Durvalumab, Avelumab, have all been investigated and approved in the setting of metastatic refractory urothelial cancer (Gupta et al. in Cancer, 9(15):1-14, 2017; Von der Maase et al. in J Clin Oncol, 23:4602-4608, 2005; Zilchi et al. in BioMed Res Int, 2017, 2017, doi: 10.1155/2017/5618174 ). Atezolizumab and Pembrolizumab have also been approved as first-line therapy in the setting of cisplatin-ineligible metastatic bladder cancer (Gupta et al. in Cancer, 9(15):1-14, 2017; Zilchi et al. in BioMed Res Int, 2017, 2017, doi: 10.1155/2017/5618174 ). Those that target cytotoxic T-lymphocyte-associated protein 4, including Ipilimumab and Tremelimumab, have also been investigated and further studies are being performed (Gupta et al. in Cancer, 9(15):1-14, 2017; Zilchi et al. in BioMed Res Int, 2017, 2017, doi: 10.1155/2017/5618174 ). This review outlines the systemic immunotherapies that have been approved or are currently being investigated.