Cortes, Jorge

AbstractNovel therapies have potential to improve outcomes in patients with acute myeloid leukemia (AML) harboring FLT3‐ITD mutations that have high risk of relapse and poor survival following standard of care (SOC) cytarabine/anthracycline‐based induction/consolidation chemotherapy. Quizartinib is a selective and highly potent FLT3 inhibitor that has shown strong single‐agent activity in relapsed or refractory (R/R) AML. This phase 1, open‐label, sequential group dose‐escalation trial (NCT 01390337) is the first evaluating safety and tolerability of quizartinib in combination with SOC chemotherapy in newly diagnosed AML (ndAML). Nineteen patients unselected for FLT3 mutational status received one of three quizartinib dihydrochloride dose levels (DL): 60 mg/d for 7 days (DL1; n = 6), 60 mg/d for 14 days (DL2; n = 7), and 40 mg/d for 14 days (DL‐1; n = 6); administered orally starting on day 4 of chemotherapy. Median age was 43.8 years. Ten patients completed induction and consolidation. Three patients experienced dose‐limiting toxicities (DLTs): 2 at DL2 (1 pericardial effusion; 1 febrile neutropenia, decreased platelet count, and QT prolongation); 1 at DL‐1 (pericarditis). Maximum tolerated dose (MTD) was identified as DL‐1. Most common grade 3/4 adverse events were febrile neutropenia (47%), neutropenia (42%), thrombocytopenia (32%), and anemia (26%). There were no apparent additional toxicities with addition of quizartinib to chemotherapy although grade ≤1 QT prolongation was observed at MTD. Sixteen patients (84%) achieved a response; 14 (74%) composite complete response; 2 (11%) morphologic leukemia‐free state. The phase 3 QuANTUM‐First trial (NCT02668653) is further evaluating the effect of quizartinib plus SOC chemotherapy in ndAML FLT3‐ITD mutated patients.

Purpose To develop a system prognostic of outcome in those undergoing allogeneic hematopoietic cell transplantation (allo HCT) for myelodysplastic syndrome (MDS). Patients and Methods We examined 2,133 patients with MDS undergoing HLA-matched (n = 1,728) or -mismatched (n = 405) allo HCT from 2000 to 2012. We used a Cox multivariable model to identify factors prognostic of mortality in a training subset (n = 1,151) of the HLA-matched cohort. A weighted score using these factors was assigned to the remaining patients undergoing HLA-matched allo HCT (validation cohort; n = 577) as well as to patients undergoing HLA-mismatched allo HCT. Results Blood blasts greater than 3% (hazard ratio [HR], 1.41; 95% CI, 1.08 to 1.85), platelets 50 × 109/L or less at transplantation (HR, 1.37; 95% CI, 1.18 to 1.61), Karnofsky performance status less than 90% (HR, 1.25; 95% CI, 1.06 to 1.28), comprehensive cytogenetic risk score of poor or very poor (HR, 1.43; 95% CI, 1.14 to 1.80), and age 30 to 49 years (HR, 1.60; 95% CI, 1.09 to 2.35) were associated with increased hazard of death and assigned 1 point in the scoring system. Monosomal karyotype (HR, 2.01; 95% CI, 1.65 to 2.45) and age 50 years or older (HR, 1.93; 95% CI, 1.36 to 2.83) were assigned 2 points. The 3-year overall survival after transplantation in patients with low (0 to 1 points), intermediate (2 to 3), high (4 to 5) and very high (≥ 6) scores was 71% (95% CI, 58% to 85%), 49% (95% CI, 42% to 56%), 41% (95% CI, 31% to 51%), and 25% (95% CI, 4% to 46%), respectively (P < .001). Increasing score was predictive of increased relapse (P < .001) and treatment-related mortality (P < .001) in the HLA-matched set and relapse (P < .001) in the HLA-mismatched cohort. Conclusion The proposed system is prognostic of outcome in patients undergoing HLA-matched and -mismatched allo HCT for MDS.

Key Points In combination with cyclophosphamide, intravenous busulfan is associated with better leukemia-free and overall survival in AML than TBI.

RAS is an oncogene frequently mutated in human cancer. RAS mutations have been reported in 10–15% of cases of acute myeloid leukemia (AML) but they appear to be less frequent among patients with myelodysplastic syndrome (MDS). The impact of RAS mutations in patients with MDS is unclear. We conducted a retrospective study in 1,067 patients with newly diagnosed MDS for whom RAS mutational analysis was available. Overall, 4% of patients carried mutant RAS alleles. Notably, FLT3 mutations, which were found in 2% of patients, were mutually exclusive with RAS mutations. Patients with RAS mutations had a higher white blood cell count as well as bone marrow blasts compared with patients carrying wild‐type RAS. However, no differences were observed between both groups regarding the risk of AML transformation (9% vs. 7%) and overall survival (395 days vs. 500 days, P = 0.057). In summary, RAS mutations are infrequent in patients with MDS and do not appear to negatively impact their outcome. Am. J. Hematol. 88:365–369, 2013. © 2013 Wiley Periodicals, Inc.

Purpose Myelofibrosis is a myeloid malignancy associated with anemia, splenomegaly, and constitutional symptoms. Patients frequently harbor JAK-STAT activating mutations that are sensitive to TG101348, a selective small-molecule Janus kinase 2 (JAK2) inhibitor. Patients and Methods In a multicenter phase I trial, oral TG101348 was administered once a day to patients with high- or intermediate-risk primary or post–polycythemia vera/essential thrombocythemia myelofibrosis. Results Fifty-nine patients were treated, including 28 in the dose-escalation phase. The maximum-tolerated dose was 680 mg/d, and dose-limiting toxicity was a reversible and asymptomatic increase in the serum amylase level. Forty-three patients (73%) continued treatment beyond six cycles; the median cumulative exposure to TG101348 was 380 days. Adverse events included nausea, vomiting, diarrhea, anemia, and thrombocytopenia; corresponding grades 3 to 4 incidence rates were 3%, 3%, 10%, 35%, and 24%. TG101348 treatment had modest effect on serum cytokine levels, but greater than half of the patients with early satiety, night sweats, fatigue, pruritus, and cough achieved rapid and durable improvement in these symptoms. By six and 12 cycles of treatment, 39% and 47% of patients, respectively, had achieved a spleen response per International Working Group criteria. The majority of patients with leukocytosis or thrombocytosis at baseline (n = 28 and n = 10, respectively) achieved normalization of blood counts after six (57% and 90%, respectively) and 12 (56% and 88%, respectively) cycles. A significant decrease in JAK2 V617F allele burden was observed at 6 months in mutation-positive patients (n = 51; P = .04), particularly in the subgroup with allele burden greater than 20% (n = 23; P < .01); the decrease was durable at 12 months. Conclusion TG101348 is well tolerated and produces significant reduction in disease burden and durable clinical benefit in patients with myelofibrosis.

Abstract Purpose: Patients with hypereosinophilic syndrome (HES) or chronic eosinophilic leukemia (CEL) that are refractory to standard therapies are difficult to manage and have significantly shortened life expectancy. Experimental Design: CD52 is a surface glycoprotein highly expressed on eosinophils. We treated 11 patients with advanced HES/CEL with alemtuzumab, a humanized anti-CD52 monoclonal antibody. Alemtuzumab was administered, in general, first in escalating doses (5, 10, 30 mg i.v. on days 1-3), then at the tolerated dose thrice per week for a total of 12 doses. Patients with complete hematologic response (CHR; normal percent and absolute eosinophil count) were allowed to continue therapy once weekly as maintenance. Results: Ten patients (91%) achieved CHR after a median of 2 weeks (0.5-5 weeks) of therapy. Bone marrow eosinophilia resolved in four of seven evaluable patients. The median duration of CHR was 3 months (1.5-17+ months). Seven of the 10 CHR patients relapsed, five while off-therapy. Two patients achieved second CHR upon alemtuzumab rechallenge. Three patients experienced mild infusion-related symptoms, two developed cytomegalovirus reactivation requiring therapy, and one developed orbital lymphoma that was successfully treated. Conclusions: Our limited experience suggests alemtuzumab to be a valuable therapy for advanced HES or CEL, refractory to standard therapies, and supports the clinical evaluation of alemtuzumab in a larger trial.

Abstract Purpose: Molecular characterization of Philadelphia chromosome–negative (Ph−) chronic myeloproliferative disorders, such as systemic mastocytosis (SM), has provided a clear rationale for investigating novel targeted therapies. The tyrosine kinase (TK) inhibitor dasatinib is 325-fold more potent against Bcr-Abl TK than imatinib in vitro, significantly inhibiting wild-type KIT and platelet-derived growth factor receptor β TKs, and is active against cells carrying the mutant KIT-D816V gene. Experimental Design: In this phase 2, open-label study, the efficacy of dasatinib (140 mg/d) was investigated in 67 patients with various Ph− myeloid disorders, including SM (n = 33; 28 KIT-D816V positive). Results: The overall response rate to dasatinib in patients with SM was 33%. Only two patients, one with SM-myelofibrosis and one with SM-chronic eosinophilic leukemia, achieved complete response (elimination of mastocytosis) lasting for 5 and 16 months, respectively. Both patients were negative for KIT-D816V mutation, had low tryptase levels, abnormal WBC counts, and anemia, and had failed prior therapy with erythropoietin. Additional nine SM patients had symptomatic response, lasting 3 to 18+ months. Complete responses were achieved in two other patients (acute myeloid leukemia and hypereosinophilic syndrome). No responses were observed among patients with myelodysplastic syndromes and primary myelofibrosis. The majority of adverse events were grade 1/2. Conclusion: These data show that dasatinib therapy may benefit a selected group of SM patients, primarily by improving their symptoms, but it does not eliminate the disease in the patients with KIT-D816V mutation.

Abstract Gain-of-function mutations of the receptor tyrosine kinase KIT play a key role in the pathogenesis of systemic mastocytosis (SM), gastrointestinal stromal tumors (GISTs), and some cases of acute myeloid leukemia (AML). Whereas KIT juxtamembrane domain mutations seen in most patients with GIST are highly sensitive to imatinib, the kinase activation loop mutant D816V, frequently encountered in SM, hampers the binding ability of imatinib. We investigated the inhibitory activity of the novel tyrosine kinase inhibitor EXEL-0862 against 2 subclones of human mast cell line-1 (HMC-1)—HMC-1.1, harboring the juxtamembrane domain mutation V560G, and HMC-1.2, carrying V560G and the activation loop mutation D816V, found in more than 80% of patients with SM. EXEL-0862 inhibited the phosphorylation of KIT in a dose-dependent manner and decreased cell proliferation in both mast cell lines with higher activity against HMC-1.2 cells. The phosphorylation of KIT-dependent signal transducer and activator of transcription-3 (STAT3) and STAT5 was abrogated upon exposure to nanomolar concentrations of EXEL-0862. In addition, EXEL-0862 induced a time- and dose-dependent proapoptotic effect in both mast cell lines and caused a significant reduction in mast-cell content in bone marrow samples from patients with SM harboring D816V and from those without the D816V mutation. We conclude that EXEL-0862 is active against KIT activation loop mutants and is a promising candidate for the treatment of patients with SM and other KIT-driven malignancies harboring active site mutations.