Tefferi, Ayalew

Abstract Adaphostin (NSC 680410), an analog of the tyrphostin AG957, was previously shown to induce Bcr/abl down-regulation followed by loss of clonogenic survival in chronic myelogenous leukemia (CML) cell lines and clinical samples. Adaphostin demonstrated selectivity for CML myeloid progenitors in vitro and remained active in K562 cells selected for imatinib mesylate resistance. In the present study, the mechanism of action of adaphostin was investigated in greater detail in vitro. Initial studies demonstrated that adaphostin induced apoptosis in a variety of Bcr/abl- cells, including acute myelogenous leukemia (AML) blasts and cell lines as well as chronic lymphocytic leukemia (CLL) samples. Further study demonstrated that adaphostin caused intracellular peroxide production followed by DNA strand breaks and, in cells containing wild-type p53, a typical DNA damage response consisting of p53 phosphorylation and up-regulation. Importantly, the antioxidant N-acetylcysteine (NAC) blunted these events, whereas glutathione depletion with buthionine sulfoximine (BSO) augmented them. Collectively, these results not only outline a mechanism by which adaphostin can damage both myeloid and lymphoid leukemia cells, but also indicate that this novel agent might have a broader spectrum of activity than originally envisioned. (Blood. 2003;102:4512-4519)

AbstractImatinib mesylate is effective in the treatment of hematologic malignancies that are characterized by either abl- or PDGFRβ- activating mutations. The drug is also active in a subset of patients with eosinophilic disorders and systemic mast cell disease (SMCD). Recently, a novel tyrosine kinase that is generated from fusion of the Fip1-like 1 (FIP1L1) and PDGFRα (PDGFRA) genes has been identified as a therapeutic target for imatinib mesylate in hypereosinophilic syndrome (HES). We used fluorescence in situ hybridization (FISH) to detect deletion of the CHIC2 locus at 4q12 as a surrogate for the FIP1L1-PDGFRA fusion. CHIC2 deletion was observed in bone marrow cells for 3 of 5 patients with SMCD associated with eosinophilia. Deletion of this locus and expression of the FIP1L1–platelet-derived growth factor receptor α (PDGFRA) fusion was also documented in enriched eosinophils, neutrophils, or mononuclear cells by both FISH and reverse transcriptase–polymerase chain reaction (RT-PCR) for one patient. While all 3 patients with the FIP1L1-PDGFRA rearrangement achieved a sustained complete response with imatinib mesylate therapy, the other two, both carrying the c-kit Asp816 to Val (Asp816Val) mutation, did not. These observations suggest that the FIP1L1-PDGFRA rearrangement occurs in an early hematopoietic progenitor and suggests that the molecular pathogenesis for a subset of SMCD patients is similar to that of HES. Screening for the FIP1L1-PDGFRA rearrangement and Asp816Val mutation will advance rational therapy decisions in SMCD.

Imatinib mesylate (Gleevec), a small molecule inhibitor of abl, kit, and platelet-derived growth factor receptor (PDGFR) tyrosine kinases, has been reported to be effective in the treatment of hypereosinophilic syndrome (HES) and a rare eosinophilia-associated chronic myeloid disorder (eos-CMD) characterized by the t(5;12)(q33;p13) cytogenetic abnormality. In the current study, we sought to confirm the preliminary observations in HES as well as evaluate the therapeutic value of imatinib in eos-CMD that is not associated with t(5;12)(q33;p13). Five patients with HES (all men, median age = 46 years) and 2 with eos-CMD (both men, aged 45 and 58 years) were treated with imatinib at a starting dose of 100 to 400 mg/day. Cytogenetic studies showed no evidence of either the bcr-abl translocation or t(5;12)(q33;p13) in any patient. Screening of exons encoding the intracellular catalytic domains and extracellular ligand binding domains of PDGFRβ (exons 2-23) and c-kit (exons 1-21) in 6 patients demonstrated mostly previously known polymorphisms. At a median follow-up of 17 weeks (range, 10-33 weeks), 2 patients with HES and 1 with eos-CMD have achieved complete clinical remission and 1 additional patient with HES has achieved a partial remission. In contrast to previous observations, all 4 responding patients had elevated serum interleukin-5 levels. Although the drug was well tolerated in most patients, a previously unrecognized treatment toxicity of acute left ventricular dysfunction occurred in a responding patient with HES within the first week of treatment. Myocardial biopsy revealed eosinophilic infiltration and degranulation, and the cardiogenic shock was reversed with the prompt institution of corticosteroid therapy.

Single-agent thalidomide (THAL) at “conventional” doses (> 100 mg/d) has been evaluated in myelofibrosis with myeloid metaplasia (MMM) based on its antiangiogenic properties and the prominent neoangiogenesis that occurs in MMM. THAL monotherapy at such doses produces approximately a 20% response rate in anemia but is poorly tolerated (an adverse dropout rate of > 50% in 3 months). To improve efficacy and tolerability, we prospectively treated 21 symptomatic patients (hemoglobin level < 10 g/dL or symptomatic splenomegaly) with MMM with low-dose THAL (50 mg/d) along with a 3-month oral prednisone (PRED) taper (beginning at 0.5 mg/kg/d). THAL-PRED was well tolerated in all enrolled patients, with 20 patients (95%) able to complete 3 months of treatment. An objective clinical response was demonstrated in 13 (62%) patients, all improvements in anemia. Among 10 patients who were dependent on erythrocyte transfusions, 7 (70%) improved and 4 (40%) became transfusion independent. Among 8 patients with thrombocytopenia (platelet count < 100 × 109/L), 6 (75%) experienced a 50% or higher increase in their platelet count. In 4 of 21 patients (19%), spleen size decreased by more than 50%. Responses observed were mostly durable after discontinuation of the PRED. The dose of THAL in this study (50 mg/d) was better tolerated than the higher doses used in previous studies. Adverse events associated with corticosteroid therapy were mild and transient. Clinical responses did not correlate with improvements in either intramedullary fibrosis or angiogenesis. THAL-PRED is well tolerated and preliminarily appears to be a promising drug regimen for treating cytopenias in patients with MMM.

Antithymocyte globulin (ATG) has recently been popularized as an effective treatment in myelodysplastic syndrome (MDS). We treated 8 anemic MDS patients (refractory anemia [RA] and refractory anemia with excess blasts [RAEB-1]) with ATG (40 mg/kg/d for 4 days) and prednisone in a phase 2 trial. The study was stopped early according to a preset termination rule because of lack of efficacy. There were no salutary responses. Toxicities included serum sickness (in all patients), transient neutropenia and thrombocytopenia, diarrhea, vomiting, and syncope with a generalized seizure. At least 3 patients had the HLA-DR15 (DR2) allele. We conclude that the risk-benefit ratio of ATG in an unselected population of MDS patients may be unfavorable, and more work is needed to define the subset of patients who will respond to ATG before its widespread use can be recommended.

A combination of magnetic cell sorting (MACS) and fluorescent in situ hybridization (FISH) techniques was used to detect clonal cytogenetic markers in different myeloid and lymphoid cell types of the peripheral blood from 4 patients with myelofibrosis with myeloid metaplasia (MMM) that was associated with either a 13q− or a 20q− karyotypic abnormality. Interphase cytogenetics studies demonstrated abnormal clonal FISH signal patterns in neutrophil, myeloid, erythroid, megakaryocyte, and B- and T-cell preparations in 3 of the 4 patients. In one patient, FISH results were within normal limits in T cells and slightly abnormal in B cells. In general, the percentage of abnormal nuclei was variable in both lymphocyte populations but always higher in B lymphocytes compared with T lymphocytes. The current study provides direct evidence for the clonal involvement of both B and T lymphocytes in MMM. A larger study is needed to clarify the relevance of the observed interpatient heterogeneity in clonal constitution.

Abstract Previous studies have reported mortality rates of about 80% in hematopoietic stem cell transplant recipients with diffuse alveolar hemorrhage. This retrospective study describes the clinical course of 48 such patients: mean age 47.7 years, 52% autologous transplant and 67% peripheral stem cell source. The hemorrhage occurred within one month of transplant in 28 patients. Symptoms included dyspnea in 92%, fever in 67%, cough in 56%, and hemoptysis in 15%. Intensive care unit admission was required in 85% and mechanical ventilation in 77%. Most of the patients were treated with intravenous methylprednisolone 1 g daily for 3 days and then tapered off after a median of 22 days. The hospital mortality was 48%. The cause of death was respiratory failure in 15 of the 23 deaths. Mortality was 28% in autologous compared with 70% in allogeneic transplant recipients (p = 0.0040). The mortality rate of patients whose hemorrhage occurred within the first 30 days of transplant was 32% compared with 70% of those with late hemorrhage (p = 0.0096). This study shows that survival rate of hematopoietic stem cell transplant recipients with diffuse alveolar hemorrhage is better than previously reported, and that early onset and autologous transplant are favorable prognostic indicators.