A phase I, open-label, dose-escalation, multicenter study of the JAK2 inhibitor NS-018 in patients with myelofibrosis

NS-018 is a Janus-activated kinase 2 (JAK2)-selective inhibitor, targeting the JAK–signal transducer and activator of transcription (STAT) pathway that is deregulated in myelofibrosis. In this phase I, dose-escalation portion of a phase I/II study, patients with myelofibrosis received oral NS-018 in continuous 28-day cycles. The primary study objective was to evaluate safety, tolerability and clinically active dose of NS-018. Forty-eight patients were treated; 23 (48%) had previously received a JAK inhibitor (JAKi). The most common drug-related adverse events were thrombocytopenia (27%)/anemia (15%) for hematologic events, and dizziness (23%)/nausea (19%) for non-hematologic events. Once daily NS-018 at 300 mg was chosen as the phase II study dose based on improved tolerability compared with higher doses. A ⩾50% reduction in palpable spleen size was achieved in 56% of patients (47% of patients with prior JAKi treatment), and improvements were observed in myelofibrosis-associated symptoms. Bone marrow fibrosis grade (local assessment) improved from baseline in 11/30 evaluable patients (37%) after 3 cycles of NS-018. JAK2 allele burden was largely unchanged. Changes in cytokine/protein levels were noted after 4 weeks of treatment. NS-018 reached peak plasma concentration in 1–2 h and did not accumulate with multiple dosing. NS-018 will be assessed in patients with previous JAKi exposure in the phase II portion.

A phase II study of decitabine and gemtuzumab ozogamicin in newly diagnosed and relapsed acute myeloid leukemia and high-risk myelodysplastic syndrome

Decitabine may open the chromatin structure of leukemia cells making them accessible to the calicheamicin epitope of gemtuzumab ozogamicin (GO). A total of 110 patients (median age 70 years; range 27-89 years) were treated with decitabine and GO in a trial designed on model-based futility to accommodate subject heterogeneity: group 1: relapsed/refractory acute myeloid leukemia (AML) with complete remission duration (CRD) <1 year (N=28, 25%); group 2: relapsed/refractory AML with CRD ⩾1 year (N=5, 5%); group 3: untreated AML unfit for intensive chemotherapy or untreated myelodysplastic syndrome (MDS) or untreated myelofibrosis (MF; N=57, 52%); and group 4: AML evolving from MDS or relapsed/refractory MDS or MF (N=20, 18%). Treatment consisted of decitabine 20 mg/m(2) daily for 5 days and GO 3 mg/m(2) on day 5. Post-induction therapy included five cycles of decitabine+GO followed by decitabine alone. Complete remission (CR)/CR with incomplete count recovery was achieved in 39 (35%) patients; group 1= 5/28 (17%), group 2=3/5 (60%), group 3=24/57 (42%) and group 4=7/20 (35%). The 8-week mortality in groups 3 and 4 was 16% and 10%, respectively. Common drug-related adverse events included nausea, mucositis and hemorrhage. Decitabine and GO improved the response rate but not overall survival compared with historical outcomes in untreated AML ⩾60 years.

Ruxolitinib: long-term management of patients with myelofibrosis and future directions in the treatment of myeloproliferative neoplasms

Considerable clinical experience regarding the long-term efficacy and safety of ruxolitinib has been gathered since the drug was approved in the USA for patients with intermediate or high-risk myelofibrosis (MF) in November 2011. Findings from the pivotal phase 3 COMFORT studies showed that ruxolitinib-associated reductions in MF-related splenomegaly and symptom burden occur rapidly and in the majority of patients. Two- and 3-year follow-up data further suggest that the benefits of ruxolitinib are durable and associated with a survival advantage compared with conventional therapies. However, careful management of treatment-related thrombocytopenia and anemia with dose modifications and supportive care is critical to allow chronic therapy. Based on preliminary evidence, ruxolitinib also allows spleen size and symptom reduction before allogeneic stem cell transplantation without negative effect on engraftment or outcomes. In recent studies, ruxolitinib provided effective management of hematologic parameters and symptoms in patients with polycythemia vera refractory to or intolerant of hydroxyurea.

Refined diagnostic criteria and classification of mast cell leukemia (MCL) and myelomastocytic leukemia (MML): a consensus proposal

Mast cell leukemia (MCL), the leukemic manifestation of systemic mastocytosis (SM), is characterized by leukemic expansion of immature mast cells (MCs) in the bone marrow (BM) and other internal organs; and a poor prognosis. In a subset of patients, circulating MCs are detectable. A major differential diagnosis to MCL is myelomastocytic leukemia (MML). Although criteria for both MCL and MML have been published, several questions remain concerning terminologies and subvariants. To discuss open issues, the EU/US-consensus group and the European Competence Network on Mastocytosis (ECNM) launched a series of meetings and workshops in 2011-2013. Resulting discussions and outcomes are provided in this article. The group recommends that MML be recognized as a distinct condition defined by mastocytic differentiation in advanced myeloid neoplasms without evidence of SM. The group also proposes that MCL be divided into acute MCL and chronic MCL, based on the presence or absence of C-Findings. In addition, a primary (de novo) form of MCL should be separated from secondary MCL that typically develops in the presence of a known antecedent MC neoplasm, usually aggressive SM (ASM) or MC sarcoma. For MCL, an imminent prephase is also proposed. This prephase represents ASM with rapid progression and 5%-19% MCs in BM smears, which is generally accepted to be of prognostic significance. We recommend that this condition be termed ASM in transformation to MCL (ASM-t). The refined classification of MCL fits within and extends the current WHO classification; and should improve prognostication and patient selection in practice as well as in clinical trials.

A phase II open-label study of the intravenous administration of homoharringtonine in the treatment of myelodysplastic syndrome

Homoharringtonine is an alkaloid inhibitor of protein synthesis with activity in myeloid malignancies. We report a phase II pilot study of homoharringtonine in myelodysplastic syndrome (MDS). Induction consisted of homoharringtonine at 2.5 mg/m(2) via continuous infusion for 7 days. Maintenance was given every 4 weeks. Nine patients were enrolled: five with refractory anaemia with excess blasts, two with refractory anaemia with excess blasts in transformation, one each with refractory anaemia and chronic myelomonocytic leukaemia respectively. Median age was 70 years (55-84) and 6 (66%) were male. Per International Prognostic Scoring System (IPSS) two patients were intermediate-1, five intermediate-2 and two high-risk. Median chemotherapy courses were one (1-3). One patient (11%) responded with complete haematological and cytogenetic remission after one course. Eight patients did not respond (four had stable disease, two progressed to acute leukaemia and two died during induction - from aspergillus pneumonia and intracerebral haemorrhage respectively). Grade 3/4 myelosuppression seen in 56% (5/9). Serious non-haematological toxicities included one case of grade 4 left bundle branch heart block and one grade 3 nephrotoxicity. Median time between courses was 42 days (35-72 days). In conclusion homoharringtonine might have clinical activity in some patients with MDS.

Biology and clinical management of myeloproliferative neoplasms and development of the JAK inhibitor ruxolitinib

Myeloproliferative neoplasms (MPN) are debilitating stem cell-derived clonal myeloid malignancies. Conventional treatments for the BCR-ABL1-negative MPN including polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) have, so far, been unsatisfactory. Following the discovery of dysregulated JAK-STAT signaling in patients with MPN, many efforts have been directed toward the development of molecularly targeted therapies, including inhibitors of JAK1 and JAK2. Ruxolitinib (previously known as INCB018424; Incyte Corporation, Wilmington, Delaware, USA) is a rationally designed potent oral JAK1 and JAK2 inhibitor that has undergone clinical trials in patients with PV, ET, and PMF. Ruxolitinib was approved on November 16, 2011 by the United States Food and Drug Administration for the treatment of intermediate or high-risk myelofibrosis (MF), including patients with PMF, post-PV MF, and post-ET MF. In randomized phase III studies, ruxolitinib treatment resulted in significant and durable reductions in splenomegaly and improvements in disease-related symptoms in patients with MF compared with placebo or best available therapy. The most common adverse events were anemia and thrombocytopenia, which were manageable and rarely led to discontinuation. This review addresses the cellular and molecular biology, and the clinical management of MPN.

Ruxolitinib for the treatment of myelofibrosis

Ruxolitinib is an orally available, ATP-competitive inhibitor, selective for tyrosine-protein kinases JAK1 and JAK2 and is the most advanced JAK1/JAK2 inhibitor in development for the treatment of myeloproliferative neoplasms. The suggested mechanism of action of ruxolitinib is attenuation of cytokine signaling via the inhibition of JAK1 and JAK2 (wild-type or mutated forms), resulting in antiproliferative and proapoptotic effects. In the phase III COMFORT-I trial conducted in patients with myelofibrosis, ruxolitinib demonstrated durable reductions in splenomegaly. The proportion of patients that achieved spleen volume reduction ≥ 35% from baseline to 24 weeks was 41.9 % with ruxolitinib versus 0.7% with placebo (P < 0.0001), as evaluated by magnetic resonance imaging or computed tomography. In the phase III COMFORT-II trial, reductions in spleen volume ≥ 35% were observed in 31.9% of patients treated with ruxolitinib versus 0% with best available therapy at week 24, and 28.5% versus 0% at week 48 (both P < 0.0001). Low toxicity, alleviation of constitutional symptoms, weight gain and improvement in general physical condition were observed with ruxolitinib treatment which may substantially improve quality of life in patients with myelofibrosis.

What are RBC-transfusion-dependence and -independence?

The term RBC-transfusion-dependence is widely-used by hematologists to describe a condition of severe anemia typically arising when erythropoiesis is reduced such that a person continuously requires ≥1 RBC-transfusions over a specified interval. Defining a person as RBC-transfusion-dependent has important implications in diverse hematological disorders especially because it strongly-correlated with decreased survival. Conversely, becoming RBC-transfusion-independent or receiving fewer RBC-transfusions over a specified interval is defined as improvement or response in many disease- and/or therapy-setting. Whether this correlates with improved survival is controversial. We used a structured expert-panel consensus panel process to define RBC-transfusion-dependence and -independence or improvement. We suggest these definitions may prove useful to persons studying or treating these diseases.

Plasma levels of JAK2 mRNA in patients with chronic myeloproliferative diseases with and without V617F mutation: implications for prognosis and disease biology

The association of V617F JAK2 expression levels with disease behavior has not been studied in patients with nonchronic myelogenous leukemia (CML) myeloproliferative disease (MPD). We found plasma levels of total JAK2 mRNA to be higher in patients with non-CML MPD (n=175) than in CML patients (n=45) and normal controls (n=58) (each P<0.001). Overall survival was studied in 68 patients and showed positive correlation with levels of total and mutant JAK2 mRNA in patients with the V617F mutation, but not those without the mutation. These findings suggest that total JAK2 expression levels play a role in the biology of the disease in V617F-positive patients, and a therapy aiming at downmodulating the expression of the total JAK2 mRNA should be considered. In conclusion, we studied JAK2 total and V6217F mutant mRNA levels in plasma. We show high levels of JAK2 expression in MPD patients and these levels correlate with survival.

Functional assessment of performance status in patients with myelofibrosis (MF): Utility and feasibility of the 6-minute walk test (6MWT)

7083

Background: Patients with Myelofibrosis (MF) suffer from significant fatigue, constitutional symptoms and splenomegaly (Mesa et. al. Cancer 2007) not improved by current therapy. The 6MWT measures functional status in cardio-pulmonary clinical trials. We undertook a prospective feasibility study of the 6MWT in MF patients for use in therapeutic clinical trials. Methods: MF patients (able to walk, normal vitals, not on a JAK2 inhibitor) were eligible. Baseline features and the MF symptom assessment form (MFSAF: Mesa et. al. Blood 2008) was administered. The 6MWT was administered in standardized fashion (American Thoracic Society: observed laps of a 30 - 35 meter long course, indoors, level, without encouragement), and then repeated for further validation. Results: Safety of the 6MWT: Fifty five MF patients were enrolled with only 2 patients (3%) stopping the 6MWT early secondary to fatigue. There were no adverse events attributable to undergoing the 6MWT in test subjects. Results of the 6MWT: Current results of our ongoing study demonstrate compared to age matched healthy volunteer controls, males with MF walk approximately 90 meters less and females with MF walk approximately 60 meters less (Table). Correlation of 6MWT Results to Patient Reported Symptoms (MFSAF): Results from the MFSAF demonstrated the fatigue (as assessed by the brief fatigue inventory (Medoza et. al. Cancer 1999) embedded in the MFSAF) showed patients with a higher BFI (i.e., more fatigued) had more impairment in the 6MWT than those with low BFI scores. Symptomatic burden as assessed by the MFSAF were typical for MF, correlation of individual symptom severity with 6MWT will require a larger trial for adequate power. Conclusions: The 6MWT can be safely performed in un-selected MF patients, and demonstrates a functional deficit compared to published controls. Validation of the ability of the 6MWT to measure functional improvements in MF patients as a response to novel therapy trials is planned.

[Table: see text]

No significant financial relationships to disclose.

Chronic myeloid leukemia (CML) with e1a2 BCR-ABL fusion transcript type: Analysis of characteristics, outcomes, and prognostic significance

7030

Background: The most common BCR-ABL fusion transcripts in CML are e13a2 (b2a2) and e14a2 (b3a2). Rarely, other transcripts like e1a2 are seen. Currently, there is no published series of data on efficacy of imatinib or other tyrosine kinase inhibitors (TKIs) in CML with e1a2. Methods: We analyzed records of 1,292 CML patients treated with TKI at our institution between January 2000 and November 2008. Results: 14 CML patients with e1a2 transcripts were identified, 9 in chronic phase (CP), 1 in accelerated phase (AP), and 4 in blast phase (BP). Median age at diagnosis was 60 (range 28–86) years, median follow-up 39.5 (range 2–109) months. Of the 9 in CP, 3 received interferon and then imatinib after interferon failure, 6 received TKI as first-line therapy (5 imatinib, 1 nilotinib): 5 achieved CHR only, 1 CCyR, 1 MCyR, 1 PCyR, and 1 did not respond to imatinib. 5 patients (2 post-interferon failure - 1 in CHR, 1 in PCyR; 3 frontline imatinib - 1 in CHR, 1 in CCyR, 1 non-responder) progressed to advanced phases (3 myeloid BP, 1 lymphoid BP, 1 AP) at a median 48 (range 4–92) months after CML diagnosis; with only 1 alive and in CMR after allogeneic SCT. AP patient received various TKIs sequentially and achieved only CHR with disappearance of clonal evolution. BP patients received Hyper-CVAD+imatinib/dasatinib or idarubicin+Ara-C; 2 did not respond, 1 had CCyR lasting 12 months with Hyper-CVAD+Imatinib and 1 had CMR after allogeneic SCT lasting 2 months. In all 14 patients, cytogenetic responses lasted 1–9 months before being lost and none (except 2) achieved MMR or CMR on imatinib or other TKI therapy. Six patients (5 CP, 1 AP) were alive at a median 39 (range 2–85) months after initial diagnosis: 4 with CHR (2 on imatinib, 1 nilotinib, 1 bosutinib), 1 with MCyR on imatinib, and 1 with CMR after allogeneic SCT. Conclusions: CML with e1a2 BCR-ABL fusion transcripts is rare and is associated with an inferior outcome to therapy with TKI, with responses being usually short-lived. These patients need to be identified as high-risk patients and monitored closely for efficacy during therapy with TKI.

No significant financial relationships to disclose.

Phase II study of vorinostat (V) in combination with idarubicin and high-dose cytarabine (IA) as front-line therapy in patients (pts) with high-risk myelodyplsatic syndrome (MDS) or acute myeloid leukemia (AML)

7004

Background: Standard induction therapy for pts with AML has not changed over the last 2 decades nor has the outcome of these pts. We demonstrated in vitro and ex vivo that the combination of an histone deacetylase inhibitor with anthraycline is synergistic (Blood 2006;108:1174); an effect that could be mediated by activation of DNA damage/repair pathways, and found that such combination is safe in phase 1 trial (Blood 2007;110:1842). We designed a phase II study of V with IA as front-line therapy for MDS/AML. Methods: Pts with untreated int-2/high-risk MDS or AML ages 15–65 with adequate liver and renal functions and PS, and EF ≥ 50% were eligible. Pts with CBF were excluded. Initial dose of V was 500 mg orally TID for 3 days followed on day 4 by IA (I:12 mg/m2/dx3; A:1.5g/m2/dx4 over 24 hrs). After induction and if in CR, pt can receive 5 cycles of consolidation with V at the same dose and IA (I:8 mg/m2/dx2; A:0.75g/m2/dx3 over 24 hours) followed by 1 year of maintenance with V. The study was powered to demonstrate improvement in PFS at 7 months and acceptable toxicity. Prior to formal initiation of the phase II, the study had a “run-in” phase to confirm the safety of the triple combination. Correlative studies include analysis of DNA repair/damage pathways. Results: 22 pts have been registered. 3 pts with relapsed/refractory AML were treated in the run-in phase. No excess toxicity was observed; 2 achieved CR and 1 CRp. Following these, 19 pts were enrolled on the phase 2 portion. 17 pts were evaluable. Median age was 49 years. Median WBC at presentation was 12.75 x 109/L. Cytogenetic analysis were abnormal in 12 (71%), complex in 10 (59%). 8 (47%) had secondary disease. 4 (23%) were Flt-3 positive. No unexpected grade 3/4 toxicities have been observed. The CR rate was 82%. 1 pt acheived a marrow CR and 2 pts died during induction. CR were universally associated with CG response. All Flt-3+ pts achieved a CR. Only 2 pts (14%) have relapsed (4 and 5 months). The median PFS has not been reached. Conclusions: The combination of IA and V is safe and active in AML/MDS. No stopping rule has been met. Results will be compared with those of a parallel IA study at MDACC. Correlative analysis are ongoing.

[Table: see text]

Hepatosplenic gamma-delta T-cell lymphoma: clinicopathological features and treatment

BACKGROUND

Hepatosplenic T-cell lymphoma (HSTCL) is a rare peripheral T-cell lymphoma; treatment with standard anthracycline-containing chemotherapy regimens has been disappointing, and an optimal treatment strategy for this patient population has not yet been determined.

METHODS

We identified 15 cases of pathologically confirmed HSTCL in the institution's database. Clinical characteristics and treatment results were reviewed.

RESULTS

Complete responses (CRs) were achieved in 7 of 14 patients who received chemotherapy. Achievement of CR was followed by hematopoietic stem-cell transplantation in three patients. Median duration of CR was 8 months (range 2 to 32+ months) with four patients currently alive and in CR at 5, 8, 12, and 32 months, respectively. Median overall survival (OS) was 11 months (range 2 to 36+ months). Patients who achieved a CR had a median OS of 13 months, compared with 7.5 months in patients who did not achieve a CR. Risk factors associated with worse outcome included male gender, failure to achieve a CR, history of immunocompromise, and absence of a T-cell receptor gene rearrangement in the gamma chain.

CONCLUSION

A better understanding of the pathophysiology of HSTCL and new therapeutic strategies are needed.

A phase II study of 5-azacitidine for patients with primary and post-essential thrombocythemia/polycythemia vera myelofibrosis

Myelofibrosis (MF; primary or post-essential thrombocythemia/polycythemia vera) is incurable clonal myeloproliferative disorder, with no effective treatment. Epigenetic changes play an important role in cancer pathogenesis through transcriptional silencing of critical tumor suppressor genes. We conducted a phase-II study to evaluate the activity of DNA methyltransferase inhibitor, 5-azacitidine, in patients with MF. Thirty-four patients (76% previously treated) received 5-azacitidine at 75 mg/m(2) subcutaneously daily for 7 days, every 4 weeks. Twelve (35%) patients had abnormal cytogenetics and 19 (70%) of 27 evaluable patients had JAK2(V617F) mutation. Responses occurred in 8 (24%) patients after a median of 5 months (range, 3-10). Partial response occurred in 1 (3%) patient (duration 22+ months) and clinical improvement in 7 (21%) patients (median duration 4 months; range, 2-8.5). Myelosuppression was the major adverse effect, with grade 3-4 neutropenia in 10 (29%) patients. Global DNA methylation assessed by the long interspersed nucleotide element (LINE) bisulfite/pyrosequencing assay decreased from 53% pretherapy to 44% on day 14 (P=0.0014) and returned to 50% at the end of the first 28-day cycle (P=0.016). 5-azacitidine is relatively well tolerated and results in induction of global hypomethylation in patients with MF, but results in limited clinical activity.

A novel unconventional antigen MPD5 elicits anti-tumor humoral immune responses in a subset of patients with polycythemia vera

In an effort to define the antigenic mechanism that contributes to beneficial therapeutic outcome in patients with polycythemia vera (PV), we screened a human testis cDNA library with serological cloning derived from sera of three PV patients who had undergone therapeutic-induced remission. As a result, we identified a novel antigen, MPD5, which belongs to the group of cryptic antigens with unconventional genomic intron/exon structure. Moreover, MPD5 elicited IgG antibody responses in a subset of PV patients who had benefited from a variety of therapies--including IFN-alpha, Hydroxyurea, Imatinib mesylate, Anagrelide, and phlebotomy--but not in untreated PV patients or healthy donors, suggesting that MPD5 is a PV-associated, therapy-related antigen. In the granulocytes of PV patients who are responsive to therapy, upregulated MPD5 expression may serve to enhance immune responses. These findings provide new insight into the mechanism underlying regulation of the self-antigen repertoire that elicits anti-tumor immune responses in patients with myeloproliferative diseases, indicating the potential of these self-antigens as targets of novel immunotherapy.

Phase I trial of intermittent administration of sorafenib (BAY 43–9006) for patients (pts) with refractory/relapsed acute myelogenous leukemia (AML)

7018

Background: Fms-like tyrosine kinase 3 (FLT3) mutations, both internal tandem duplication (ITD) and point mutations, occur in approximately 30% of pts with AML and confer poor prognosis. Sorafenib is an oral multi-kinase inhibitor highly potent against mutant FLT3 (IC50 1–3 nM). Based on preclinical data, this study was initiated to assess two intermittent administration schedules of sorafenib. Methods: This phase I trial evaluated the safety and efficacy of sorafenib in 15 pts with refractory/relapsed AML (n=14) or high-risk myelodysplastic syndrome (n=1). Pts were randomized to sorafenib for 5 days per week (arm A; n=8) or for 14 days every 21 days (arm B; n=7). In both arms, dose level (DL) 1 was 200 mg twice daily in 21-day cycles. Successive DLs were 600, 800, and 1,200 mg daily on a standard 3+3 design. Pre- and post-treatment peripheral blood (PB) and bone marrow (BM) samples were obtained for evaluation of FLT3 status and phospho and total FLT3 and ERK expression. Results: 10 (67%) of 15 pts (all with AML) received at least 1 cycle of sorafenib (5 in arm A, 5 in arm B) and 5 discontinued sorafenib (3 in arm A, 2 in arm B): 3 due to disease progression, and 2 due to infectious complications. Pts who received at least 1 cycle were treated at DL-1 (n=4) or DL-2 (n=6). Median age was 61 years (range, 51–81), number of prior therapies 4 (range, 1–6), and time from diagnosis to sorafenib 9 months (range, 5–46). Sorafenib was well tolerated; the MTD has not been reached. Six (60%) of 10 pts receiving at least 1 cycle of sorafenib (3 in arm A, 3 in arm B) responded. Responses were transient and only occurred in pts with FLT3-ITD mutation. The median blast percentage before and after sorafenib start was 59% and 0% in PB (p=0.008) and 66% and 32% in BM (p=0.03). Serial determinations of phosphorylation status following sorafenib (at 0, 2, 24,120 hours) in pts with FLT3-ITD, demonstrated inhibition of phospho-FLT3 in 3/3 and phospho-ERK in 5/5 pts. Conclusions: Sorafenib is safe in AML and has encouraging activity at the relatively low doses tested thus far, particularly in pts with FLT3-ITD mutation. Clinical studies of sorafenib in combination with chemotherapy or other targeted agents are warranted in pts with AML expressing this abnormality.

[Table: see text]

Combination therapy with alemtuzumab and pentostatin is effective and has acceptable toxicity in patients with T-lymphoid neoplasms

7037

Background: The development of effective therapeutic strategies for T-lymphoid neoplasms has been difficult partly due to the paucity of clinical trials. These neoplasms are generally refractory to traditional chemotherapy regimens. Alemtuzumab and pentostatin have response rates of 50% to 65% when used individually to treat various T-cell leukemias and lymphomas. However, most responses are partial and of limited duration. Methods: We have treated 20 patients (pts) with T-lymphoid malignancies (11 T-PLL, 1 ATL, 1 PTCL, 2 T- ALL, 3 γd-T cell hepatosplenic lymphoma, 2 T-LGL) with a combination of alemtuzumab 30 mg IV, 3 times weekly for up to 3 months and pentostatin 4 mg/m2 weekly×4 followed by alternate weekly administration for up to 6 months. Prophylactic antibiotics were administered during the treatment and for 2 months after its completion. Results: The median age of pts was 57 yrs (range, 22 –79 yrs), median WBC was 43.9×109/L (range 0.6 –279.5 x109/L), and median serum β2M was 4.1 mg/L (range, 1.7 –10.8 mg/L). Four pts had splenomegaly, and 6 lymphadenopathy. Thirteen had prior therapy (median 2). Twelve pts have responded (10 CR, 2 PR) for an overall response rate of 60% (including 8 of 11 T-PLL, 1 of 1 ATL, 0 of 2 T-ALL, 2 of 3γd-T cell hepatosplenic lymphoma, 0 of 1 PTCL and 1 of 2 T-LGL). Monoclonal T-cell receptor chain gene rearrangements were detected by PCR in 18 pts and became negative in 5 of 7 evaluable pts in CR. Median response duration has not been reached (range, 0 to 78 weeks). 3 pts have proceeded to allogeneic stem cell transplant, 4 (1 with ATL, 2 with T-PLL, and 1 with T-LGL) have died from disease progression after a response, and 8 were refractory to therapy. Opportunistic infections included reactivation of CMV in 7 pts, reactivation of HSV in 1 pt, recurrence of pre-existing Serratia pneumonia in 1 pt and Aspergillus pneumonia in 2 pts. Unexplained, marked and sustained pancytopenia occurred in 2 pts. Other toxicities were mainly grade 1 and 2 and included nausea, fever, edema, and shortness of breath. Conclusions: The combination of alemtuzumab and pentostatin is feasible and effective in T-cell neoplasms. Although infections including CMV reactivation are a concern, they may be minimized with adequate prophylactic antibiotic therapy.

No significant financial relationships to disclose.

Dasatinib therapy for patients with Philadelphia-negative (ph-) myeloproliferative disorders (MPDs), including systemic mastocytosis

7086

There are no curative medical therapies for Ph- MPDs. Over last several years several of the MPDs have been associated with the abnormal expression of selected tyrosine kinases (e.g. c-kit in SM) and others are suspected to be involved too. Therefore, we engaged in conducting a Phase II study with dasatinib, an orally available multi targeted kinase inhibitor, for patient with Ph- MPDs. Dasatinib is administered at 70 mg PO BID continuously (one month equals one cycle). Response is assessed every 3 cycles, and the therapy is discontinued in those without response after 6 cycles of therapy. Patients are observed for any toxicity; in such cases the dose of dasatinib is adjusted to 50 mg PO BID, then to 40 mg PO BID, or discontinued. The study is ongoing and has enrolled 55 patients; 44 are evaluable for response and toxicity, including 24 with SM (6 with aggressive SM, 4 with SM and associated hematologic non-mast cell disease and 14 with indolent SM with uncontrolled symptoms despite optimal supportive care measures), 10 CIMF, 6 HES, 3 unclassifiable MPD and one PV. Median age is 65 years (range, 27–75); 25 males and 19 females. The overall response rate in SM was 42% (10 pts). Of those, two patients (8%) achieved complete remission, one with SM-CIMF, and one with SM-HES. Both were c-KIT mutation negative and had low, not significant tryptase levels. Both were anemic (Hb 9.4g/dL) and failed erythropoietin therapy, and had abnormal WBC differential; one had low platelets (90×109/L). Symptoms related to SM improved significantly in additional 8 patients, however, no significant response in percentage of bone marrow mast cells or blood tryptase levels have been observed so far. The 6 patients with HES had previously failed imatinib therapy and had no evidence of the FIP1L1-PDGFRA fusion transcript; one achieved complete remission (normalization of blood and bone marrow eosinophil percentage) while others did not respond. No responses have been recorded in patients with CIMF, PV and unclassifiable MPD. No grade 4 toxicity has been observed. Dasatinib is active in SM (overall response rate 42%) mainly by improving symptoms. Updated clinical results on all enrolled patients will be presented.

No significant financial relationships to disclose.

Molecular targeting in acute myeloid leukemia (AML) therapy: APcK110 is a new inhibitor of c-Kit activity in AML blasts

7019

Background: Tyrosine kinases (TK) are important for most cellular functions and require stringent control and regulation. C- Kit, a TK and transmembrane receptor for stem cell factor, plays a crucial role in hematopoiesis. Mutations of c-Kit can contribute to AML pathophysiology and have been associated with shorter survival and higher relapse risk following standard AML therapy. On the other hand, responses have been observed following TK inhibitor therapy such as imatinib. Identification of c-Kit or its pathways in AML leukemogenesis and development of new compounds targeting these mutations may therefore hold promise for therapy. Methods: APcK110 is the result of a structure-based design of c-Kit inhibitors and was derived of a set of compounds with favorable IC50 values in a c-Kit kinase assay. Here we present results of the activity and mechanism of action of APcK110. We used the mastocytosis cell line HMC1.1 carrying an activating c-Kit mutation and two AML lines (OCIM2 and OCI/AML3) as well as primary samples from patients with AML. Results: We demonstrate that: (1) APcK110 inhibits proliferation of all three cell lines in a dose dependent fashion using an MTT assay. Inhibition of proliferation is most significant in the SCF-dependent cell line OCI/AML3; (2) inhibition of OCIM2 cells (SCF-responsive) by APcK110 can be enhanced when adding SCF suggesting recruitment of c-Kit-dependent signaling components and increased activity of the c-Kit inhibitor under these circumstances; (3) APcK110 is a more potent inhibitor of OCI/AML3 proliferation than imatinib and dasatininb; (4) using Western immunoblotting, APcK110 decreases levels of phospho-Akt, phospho-Stat3 and 5 in a time- and dose-dependent fashion demonstrating activity of APcK110 on c-Kit downstream signaling pathways; (5) APcK110 induces apoptosis by cleavage of caspase 3 and PARP; (6) APcK110 inhibits proliferation of primary AML cells in a clonogenic assay, but does not affect proliferation of normal controls. Conclusions: APcK110 is a potent inhibitor of AML cell lines and primary samples from patients with AML. Activation of c-Kit or downstream pathways increases activity of APcK110. APcK110 and similar compounds should be evaluated in clinical trials of patients with AML.

No significant financial relationships to disclose.

The novel tyrosine kinase inhibitor EXEL-0862 induces apoptosis in human FIP1L1-PDGFR-α-expressing cells through caspase-3-mediated cleavage of Mcl-1

The FIP1-like-1 (FIP1L1)-platelet-derived growth factor receptor-alpha (FIP1L1-PDGFR-alpha) fusion kinase causes hypereosinophilic syndrome (HES) in a defined subset of patients. Imatinib mesylate is a potent inhibitor of ABL but also of PDGFR-alpha, and has been associated with durable hematologic responses in patients with HES. However, development of mutations in the tyrosine kinase domain may hamper the activity of tyrosine kinase inhibitors (TKIs), which suggests that novel agents are warranted to prevent or overcome resistance. We evaluated the efficacy of the novel TKI EXEL-0862 in FIP1L1-PDGFR-alpha-expressing cell lines and in cells from a patient with HES harboring the FIP1L1-PDGFR-alpha gene. EXEL-0862 inhibited the proliferation of EOL-1 and imatinib-resistant T674I FIP1L1-PDGFR-alpha-expressing cells and resulted in potent inhibition of the phosphorylation of PDGFR-alpha and downstream proteins STAT3 and Erk1/2, both in vitro and ex vivo. Moreover, EXEL-0862 induced apoptotic death in EOL-1 cells and imatinib-resistant T674I FIP1L1-PDGFR-alpha-expressing cells, and resulted in significant downregulation of the antiapoptotic protein Mcl-1 through a caspase-dependent mechanism. Our data establish EXEL-0862 as a solid candidate for the targeted treatment of patients with FIP1L1-PDGFR-alpha-positive HES.

Monocytosis is an adverse prognostic factor for survival in younger patients with primary myelofibrosis

We recently developed a modified Dupriez prognostic scoring system (PSS) that effectively discriminated between high-, intermediate-, and low-risk young patients (age < or =60 years) with primary myelofibrosis (PMF) based on the respective presence of none, one, or two or more of the following parameters: hemoglobin <10 g/dL, leukocyte count <4 or >30 x 10(9)L(-1), and platelet count <100 x 10(9)L(-1). The current study (n=129; median age, 52 years; 69 males) reveals, on multivariable analysis, that an absolute monocyte count of > or =1 x 10(9)L(-1) carries an independent predictive value (p=0.02), for an inferior survival, in addition to that provided by hemoglobin level (p=0.002), platelet count (0.02), and leukocyte count (p=0.16). The inclusion of the monocyte count as a fourth risk factor enabled the construction of a new and improved Mayo PSS; median survival was 173, 61, and 26 months in the absence of all four (low-risk), three (intermediate-risk), or two or less (high-risk) adverse features, respectively (p<0.0001). The independent prognostic value of monocytosis was validated in a separate database of 97 patients with PMF from another institution.

Levels of soluble HLA-I and beta2M in patients with acute myeloid leukemia and advanced myelodysplastic syndrome: association with clinical behavior and outcome of induction therapy

beta-2 Microglobulin (beta2M), a subunit of human leukocyte antigen-class I (HLA-I), is well established as a marker of prognosis in various solid tumors and hematologic malignancies. The prognostic role of intact free-circulating HLA-I (sHLA-I) is less well understood. We compared the clinical relevance of plasma levels of sHLA-I and beta2M in patients with acute myeloid leukemia (AML; n=209) or advanced myelodysplastic syndrome (MDS; n=98). sHLA-1 and beta2M levels were significantly higher in AML and MDS patients than in control subjects, but did not differ significantly between the two disease groups. In AML patients, multivariate analysis showed both sHLA-1 and beta2-M to be highly predictive of complete remission (CR), survival and duration of complete response (CRD). In MDS, the predictive value of the two markers differed substantially from one another: beta2M was associated with survival, CR and CRD, whereas sHLA-I was not. These findings not only establish the role of sHLA-I as a tumor marker in AML but also support that MDS is clinically and biologically distinct from AML. sHLA-I has been reported to be an immunomodulator inhibiting the cytotoxic effects of T-lymphocytes, which may offset its predictive value for disease aggressiveness in patients with MDS.

'Idiopathic' eosinophilia with an Occult T-cell clone: prevalence and clinical course

In a study of 99 consecutive patients with "idiopathic" eosinophilia, clonal T-cells were demonstrated in blood, bone marrow, or other tissue samples of 14 patients including 6 who had an overt T-cell malignancy. The remaining eight patients (approximately 8%) with an "Occult" T-cell clone had predominantly cutaneous disease and FIP1L1-PDGFRA was absent in all six evaluable patients. Two patients were effectively treated with low-dose oral cyclophosphamide or methotrexate whereas Gleevec treatment was ineffective in another two patients. Two patients (25%) transformed into cutaneous T-cell lymphoma after 3-8 years of eosinophilic prodrome.

Frequency and clinical significance of BCR-ABL mutations in patients with chronic myeloid leukemia treated with imatinib mesylate

Mutations of the BCR-ABL kinase domain are a common mechanism of resistance to imatinib in chronic myeloid leukemia. We screened for mutations 171 patients failing imatinib therapy. Sixty-six mutations in 23 amino acids were identified in 62 (36%) patients not responding to imatinib. Phosphate-binding loop (P-loop) mutations were the most frequent (n=24; 36%). By multivariate analysis, factors associated with development of mutations were older age (P=0.026) prior interferon therapy (P=0.026), and accelerated phase or blast phase at time of imatinib failure (P=0.001). After a median follow-up of 38 months (range, 4-68 months) from the start of imatinib therapy, seven patients with non-P-loop and two with P-loop mutation died. By multivariate analysis, development of clonal evolution and higher percentage of peripheral blood basophils were associated with worse survival from the time of imatinib failure. Mutation status had no impact on survival. When survival was measured from the time therapy started, non-P-loop mutations together with duration of response and transformation at the time of failure to imatinib were associated with shorter survival. In conclusion, P-loop mutations were not associated with poor outcome, suggesting that the prognosis of patients who fail imatinib is multifactorial.