Comparison of toxicity and outcome in patients with acute myeloid leukemia treated with high-dose cytosine arabinoside consolidation after induction with a regimen containing idarubicin or daunorubicin

AXL receptor tyrosine kinase: a possible therapeutic target in acute promyelocytic leukemia

BACKGROUND

Acute promyelocytic leukemia (APL) is a subset of acute myeloid leukemia (AML) which is characterized by the fusion of promyelocytic leukemia PML and retinoic acid receptor- alpha (RAR-alpha) genes. All-trans retinoic acid (ATRA) and/or arsenic trioxide (ATO) have resulted in durable cytogenetic and molecular remissions in most APL patients and have altered the natural history of the disease. Most APL patients treated with ATRA and/or ATO are now anticipated to have a nearly normal life expectancy. Unfortunately, relapse and resistance to the current treatment occur in APL patients and the outcome remains dismal in these refractory patients. AXL receptor tyrosine kinase (AXL-RTK) has been shown to increase tumour burden, provide resistance to therapy and is critical to maintain cancer stem cells (CSCs) in chronic myeloid leukemia (CML) by stabilizing β-catenin in the Wnt/β-catenin signalling pathway. However, the role of AXL-RTK has not been explored in PML/RARα-positive APL. This study aimed to explore the role of AXL-RTK receptor in PML/RARα-positive APL.

METHODS AND RESULTS

By using biochemical and pharmacological approaches, here we report that targeting of AXL-RTK is related to the down-regulation of β-catenin target genes including c-myc (p < 0.001), AXIN2 (p < 0.001), and HIF1α (p < 0.01) and induction of apoptosis in PML/RARα-positive APL cell line. Resistance to all-trans retinoic acid (ATRA) was also overcomed by targeting AXL-RTK with R428 in APL (p < 0.05).

CONCLUSION

Our results provide clear evidence of the involvement of AXL-RTK in leukemogenic potential of PML/RARα-positive APL and suggest targeting of AXL-RTK in the treatment of therapy resistant APL patients.

Evaluating medical resource utilization and costs associated with thrombocytopenia in chronic liver disease patients

OBJECTIVE

Thrombocytopenia (TCP), defined as platelet counts <150,000/µL, is a common complication of severe chronic liver disease (CLD). This retrospective study estimated the prevalence of thrombocytopenia in a large population of CLD patients and compared medical resource utilization and medical care costs by TCP status.

METHODS

A retrospective analysis was conducted on a longitudinal administrative claims database from a large US commercial health plan. Patients assigned CLD diagnosis codes from January 1, 2000-December 31, 2003 were identified; annual ambulatory visits, ER visits, inpatient stays, and general and CLD-related medical care costs for patients with vs without TCP (identified using diagnosis codes and platelet count data if available) were compared.

RESULTS

Of 56,445 patients with an ICD-9-CM diagnosis for CLD, 1289 (2.3%) had a diagnosis for TCP. CLD patients with vs without a TCP diagnosis had >2.5-times the annual number of liver disease-related ambulatory visits (3.6 vs 1.4; odds ratio [OR] = 2.6, p < 0.01); were 13-times more likely to have a liver-related inpatient stay (OR = 13.0, p < 0.01); were nearly 4-times more likely to have a liver-related ER visit (OR = 3.9, p < 0.01); had 3.5-fold greater mean annual overall medical care costs ($43,560 vs $12,270, p < 0.01); and had 7-fold greater annual liver disease-related medical care costs ($9940 vs $1420, p < 0.01). Similar results were seen for patients with platelet count data indicating TCP.

LIMITATIONS

CLD and TCP are not always diagnosed, nor is diagnosis uniform or standardized; administrative claims data are subject to coding errors, and individuals covered are not necessarily representative of the general US population. The number of CLD patients in this study with TCP (n = 1289) is small relative to that expected in the general US population.

CONCLUSIONS

In this analysis, CLD patients with TCP used significantly more medical resources and incurred significantly higher medical care costs than those without TCP.

A randomized comparison of 4 courses of standard-dose multiagent chemotherapy versus 3 courses of high-dose cytarabine alone in postremission therapy for acute myeloid leukemia in adults: the JALSG AML201 Study

We conducted a prospective randomized study to assess the optimal postremission therapy for adult acute myeloid leukemia in patients younger than 65 years in the first complete remission. A total of 781 patients in complete remission were randomly assigned to receive consolidation chemotherapy of either 3 courses of high-dose cytarabine (HiDAC, 2 g/m(2) twice daily for 5 days) alone or 4 courses of conventional standard-dose multiagent chemotherapy (CT) established in the previous JALSG AML97 study. Five-year disease-free survival was 43% for the HiDAC group and 39% for the multiagent CT group (P = .724), and 5-year overall survival was 58% and 56%, respectively (P = .954). Among the favorable cytogenetic risk group (n = 218), 5-year disease-free survival was 57% for HiDAC and 39% for multiagent CT (P = .050), and 5-year overall survival was 75% and 66%, respectively (P = .174). In the HiDAC group, the nadir of leukocyte counts was lower, and the duration of leukocyte less than 1.0 × 10(9)/L longer, and the frequency of documented infections higher. The present study demonstrated that the multiagent CT regimen is as effective as our HiDAC regimen for consolidation. Our HiDAC regimen resulted in a beneficial effect on disease-free survival only in the favorable cytogenetic leukemia group. This trial was registered at www.umin.ac.jp/ctr/ as #C000000157.

Rapid and selective death of leukemia stem and progenitor cells induced by the compound 4-benzyl, 2-methyl, 1,2,4-thiadiazolidine, 3,5 dione (TDZD-8)

Leukemia is thought to arise from malignant stem cells, which have been described for acute and chronic myeloid leukemia (AML and CML) and for acute lymphoblastic leukemia (ALL). Leukemia stem cells (LSCs) are relatively resistant to current chemotherapy and likely contribute to disease relapse and progression. Consequently, the identification of drugs that can efficiently eradicate LSCs is an important priority. In the present study, we investigated the antileukemia activity of the compound TDZD-8. Analysis of primary AML, blast crisis CML (bcCML), ALL, and chronic lymphoblastic leukemia (CLL) specimens showed rapid induction of cell death upon treatment with TDZD-8. In addition, for myeloid leukemias, cytotoxicity was observed for phenotypically primitive cells, in vitro colony-forming progenitors, and LSCs as defined by xenotransplantation assays. In contrast, no significant toxicity was observed for normal hematopoietic stem and progenitor cells. Notably, cell death was frequently evident within 2 hours or less of TDZD-8 exposure. Cellular and molecular studies indicate that the mechanism by which TDZD-8 induces cell death involves rapid loss of membrane integrity, depletion of free thiols, and inhibition of both the PKC and FLT3 signaling pathways. We conclude that TDZD-8 uses a unique and previously unknown mechanism to rapidly target leukemia cells, including malignant stem and progenitor populations.

The coexpression of the apoptosis-related genes bcl-2 and wt1 in predicting survival in adult acute myeloid leukemia

The Wilms tumor gene wt1 and the protooncogene bcl-2 are upregulated in acute myeloid leukemia (AML) and are known to regulate or to inhibit the onset of apoptosis. Since wt1 has been shown to regulate the expression of bcl-2, we investigated the association of the expression of these genes and their prognostic relevance in AML. Leukemic blasts from the bone marrow of 152 patients with newly diagnosed AML were analyzed for bcl-2 and wt1 mRNA expression using RT-PCR and quantitative PCR. Therapy outcome was correlated with the level of bcl-2 and wt1 transcripts. Bcl-2-specific mRNA was detectable in 127/152 (84%) patients and wt1 mRNA in 113/152 (74%) patients with AML. In monocytic subtypes the frequency of bcl-2 and wt1 transcripts was significantly lower. The expression of bcl-2 mRNA was correlated significantly with that of wt1 mRNA (P < 0.0001). In AML patients <60 years, high expression of bcl-2 and wt1 was associated with a reduced rate of continuing complete remission (CCR, P = 0.002 and P = 0.005, respectively) and increased death rate (P = 0.0002 and P = 0.04, respectively) in contrast to patients >60 years, where the expression of bcl-2 or wt1 had no prognostic impact. Based on the coexpression of bcl-2 and wt1, we established a prognostic model defining three risk groups with significant differences in CCR rate (P = 0.01), overall survival (P < 0.04) and disease-free survival (P < 0.03). Thus, bcl-2 and wt1 mRNA expression are associated with response and long-term outcome in AMLs. The coexpression of these genes allows determination of prognostic groups with high predictive value for overall and disease-free survival.

Purging of G-CSF-mobilized peripheral autografts in acute leukemia with mafosfamide and amifostine to protect normal progenitor cells

In the present study the in vitro growth of CFU-GM from PBPC of patients with AML (n = 11), purged with mafosfamide alone or a combination of mafosfamide and amifostine, was compared to historical controls of mafosfamide-purged bone marrow (AML CR1, n = 16). Two patients were transplanted with mafosfamide and mafosfamide/amifostine pretreated PBPC autografts. The in vitro experiments demonstrated a significantly higher resistance of peripheral blood derived CFU-GM to mafosfamide (median ID95 190 microg mafosfamide/ml) compared with bone marrow derived CFU-GM (median ID95130 microg/ml). Preincubation with amifostine significantly further increased the median ID95 to 245 microg/ml. The clinical results showed short recovery times for neutrophils >500/microl (9 and 13 days) and platelets >20 000/microl (12 and 21 days) and stable long-term engraftment with one relapse at day +118 and one patient in CR at day 760 after transplantation. The in vitro results show a significant advantage of PBPC over bone marrow-derived progenitors for purging with mafosfamide. Furthermore, a protective effect from mafosfamide of amifostine on normal progenitors could be demonstrated. The clinical results demonstrate the clinical feasibility of using mafosfamide-purged autologous PBPCT without impairing the short-term and long-term repopulating capacities of the autografts.