Treatment options for relapsed acute promyelocytic leukaemia

Modern molecular technology makes it possible to detect minimal residual acute promyelocytic leukaemia (APL) when the marrow remains in complete remission (CR). Thus, an important question, and the first to be discussed, is whether patients should be treated at molecular relapse, rather than only at haematological relapse. The second question to be addressed is when the various options for treatment of relapsed APL-i.e. all-trans retinoic acid (ATRA) and anthracyclines, arsenic trioxide (ATO), gemtuzumab ozogamycin (GO, 'mylotarg'), and allogeneic or autologous stem cell transplant-should be used. We suggest that patients with relapsed APL have different prognoses and that, accordingly, they should not all be treated identically. We note the significance of extramedullary relapse. We conclude with a summary of treatment recommendations and a discussion of new therapies that might be useful in the future.     

G‐CSF Priming,clofarabine, and high dose cytarabine (GCLAC) for upfront treatment of acute myeloid leukemia,advanced myelodysplastic syndrome or advanced myeloproliferative neoplasm

Prior study of the combination of clofarabine and high dose cytarabine with granulocyte colony‐stimulating factor (G‐CSF) priming (GCLAC) in relapsed or refractory acute myeloid leukemia resulted in a 46% rate of complete remission despite unfavorable risk cytogenetics. A multivariate analysis demonstrated that the remission rate and survival with GCLAC were superior to FLAG (fludarabine, cytarabine, G‐CSF) in the relapsed setting. We therefore initiated a study of the GCLAC regimen in the upfront setting in a multicenter trial. The objectives were to evaluate the rates of complete remission (CR), overall and relapse‐free survival (OS and RFS), and toxicity of GCLAC. Clofarabine was administered at 30 mg m^?2 day^?1 × 5 and cytarabine at 2 g m^?2 day^?1 × 5 after G‐CSF priming in 50 newly‐diagnosed patients ages 18–64 with AML or advanced myelodysplastic syndrome (MDS) or advanced myeloproliferative neoplasm (MPN). Responses were assessed in the different cytogenetic risk groups and in patients with antecedent hematologic disorder. The overall CR rate was 76% (95% confidence interval [CI] 64–88%) and the CR + CRp (CR with incomplete platelet count recovery) was 82% (95% CI 71–93%). The CR rate was 100% for patients with favorable, 84% for those with intermediate, and 62% for those with unfavorable risk cytogenetics. For patients with an antecedent hematologic disorder (AHD), the CR rate was 65%, compared to 85% for those without an AHD. The 60 day mortality was 2%. Thus, front line GCLAC is a well‐tolerated, effective induction regimen for AML and advanced myelodysplastic or myeloproliferative disorders. Am. J. Hematol. 90:295–300, 2015. © 2014 Wiley Periodicals, Inc.     

Modulation of angiogenesis in patients with myelodysplastic syndrome

Current investigations have revealed that angiogenesis plays a role in the pathogenesis of high-risk myelodysplastic syndrome (MDS) and acute myeloid leukemia, and in the mechanisms of disease progression. Secretion of cytokines and growth factors modulates angiogenesis in the marrow leading to increased vascularity and sustenance of the clonal population. For high-risk MDS patients older than 60 years who are not eligible for aggressive chemotherapy or stem cell transplant, there are few therapeutic options other than supportive treatment. Recent delineation of the pathobiology of MDS has resulted in the development of new agents and treatment modalities that impact on these mechanisms. One of the features of bone marrow pathology is the presence of new vessels, which appear to sustain growth and the hypercellularity of the marrow. Blocking angiogenesis may reduce the microvessel density of the marrow, cellularity, and disease progression. Angiogenesis can be targeted by inhibition of vascular endothelial growth factor (VEGF), which modulates new vessel growth, by the use of antibodies aimed at VEGF and its receptors, as well as receptor tyrosine kinases that block VEGF signaling. Other agents include inhibitors of farnesyl transferase and protein kinase C, which affect upstream modulators of growth factors and their receptor interactions; matrix metalloproteinases, which disrupt matrices and adhesion function promoting vessel growth; and other inhibitors with broader function, such as endostatin, thalidomide, and related analogues.     

Randomized phase II study of fludarabine + cytosine arabinoside + idarubicin +/- all-trans retinoic acid +/- granulocyte colony-stimulating factor in poor prognosis newly diagnosed acute myeloid leukemia and myelodysplastic syndrome

Preclinical data suggest that retinoids, eg, all-trans retinoic acid (ATRA), lower concentrations of antiapoptotic proteins such as bcl-2, possibly thereby improving the outcome of anti-acute myeloid leukemia (AML) chemotherapy. Granulocyte colony-stimulating factor (G-CSF) has been considered to be potentially synergistic with ATRA in this regard. Accordingly, we randomized 215 patients with newly diagnosed AML (153 patients) or high-risk myelodysplastic syndrome (MDS) (refractory anemia with excess blasts [RAEB] or RAEB-t, 62 patients) to receive fludarabine + ara-C + idarubicin (FAI) alone, FAI + ATRA, FAI + G-CSF, or FAI + ATRA + G-CSF. Eligibility required one of the following: age over 71 years, a history of abnormal blood counts before M.D. Anderson (MDA) presentation, secondary AML/MDS, failure to respond to one prior course of chemotherapy given outside MDA, or abnormal renal or hepatic function. For the two treatment arms containing ATRA, ATRA was given 2 days (day-2) before beginning and continued for 3 days after completion of FAI. For the two treatment arms including G-CSF, G-CSF began on day-1 and continued until neutrophil recovery. Patients with white blood cell (WBC) counts >50,000/microL began ATRA on day 1 and G-CSF on day 2. Events (death, failure to achieve complete remission [CR], or relapse from CR) have occurred in 77% of the 215 patients. Reflecting the poor prognosis of the patients entered, the CR rate was only 51%, median event-free survival (EFS) time once in CR was 36 weeks, and median survival time was 28 weeks. A Cox regression analysis indicated that, after accounting for patient prognostic variables, none of the three adjuvant treatment combinations (FAI + ATRA, FAI + G, FAI + ATRA + G) affected survival, EFS, or EFS once in CR compared with FAI. Similarly, there were no significant effects of either ATRA ignoring G-CSF, or of G-CSF ignoring ATRA. As previously found, a diagnosis of RAEB or RAEB-t rather than AML was insignificant. There were no indications that the effect of ATRA differed according to cytogenetic group, diagnosis (AML or MDS), or treatment schedule. Logistic regression analysis indicated that, after accounting for prognosis, addition of G-CSF +/- ATRA to FAI improved CR rate versus either FAI or FAI + ATRA, but G-CSF had no effect on the other outcomes. We conclude that addition of ATRA +/- G-CSF to FAI had no effect on CR rate, survival, EFS, or EFS in CR in poor prognosis, newly diagnosed AML or high-risk MDS.     

Clinical relevance of vascular endothelial growth factor receptors 1 and 2 in acute myeloid leukaemia and myelodysplastic syndrome

We have previously reported that high levels of cellular vascular endothelial growth factor (VEGF) protein correlated with short survival of patients with acute myeloid leukaemia (AML). As VEGF exerts its effects via two receptors, VEGF receptor 1 (VEGFR-1) and VEGFR-2, we evaluated the significance of VEGFR-1 and VEGFR-2 protein levels in AML and myelodysplastic syndrome (MDS), and their relationship to VEGF protein levels. Western blot analysis and radioimmunoassay confirmed and quantified specific protein levels in bone marrow samples from 41 MDS and 66 AML previously untreated patients. VEGFR-1 levels were significantly higher in AML than in MDS (P = 0.0004), but no significant difference was found in the VEGFR-2 levels (P = 0.5). No significant correlation between VEGFRs levels and duration of survival was found. VEGF protein levels were significantly higher in MDS than in AML (P < 0.0001). A Cox proportional-hazard regression model showed increasing VEGF levels to significantly correlate with shorter survival of patients with MDS (P = 0.008), a finding similar to our previous report of the inverse relationship between VEGF levels and survival of AML patients. We found a significant correlation between VEGF and VEGFR-2 levels in both AML and MDS (P < 0.0000001 andP < 0.0002 respectively) but not between VEGF and VEGFR-1 levels. These data suggest that VEGF expression, rather than the expression of its receptors, is the determining factor in the biological behaviour of AML and MDS, and that VEGFRs are differentially expressed in AML and MDS.