A B S T R A C T PurposeYounger patients with acute myeloid leukemia (AML) harboring NPM1 mutations without FLT3-internal tandem duplications (ITDs; NPM1-positive/FLT3-ITD-negative genotype) are classified as better risk; however, it remains uncertain whether this favorable classification can be applied to older patients with AML with this genotype. Therefore, we examined the impact of age on the prognostic significance of NPM1-positive/FLT3-ITD-negative status in older patients with AML. Patients and MethodsPatients with AML age Ն 55 years treated with intensive chemotherapy as part of Southwest Oncology Gorup (SWOG) and UK National Cancer Research Institute/Medical Research Council (NCRI/MRC) trials were evaluated. A comprehensive analysis first examined 156 patients treated in SWOG trials. Validation analyses then examined 1,258 patients treated in MRC/NCRI trials. Univariable and multivariable analyses were used to determine the impact of age on the prognostic significance of NPM1 mutations, FLT3-ITDs, and the NPM1-positive/FLT3-ITD-negative genotype. ResultsPatients with AML age 55 to 65 years with NPM1-positive/FLT3-ITD-negative genotype treated in SWOG trials had a significantly improved 2-year overall survival (OS) as compared with those without this genotype (70% v 32%; P Ͻ .001). Moreover, patients age 55 to 65 years with NPM1-positive/FLT3-ITD-negative genotype had a significantly improved 2-year OS as compared with those age Ͼ 65 years with this genotype (70% v 27%; P Ͻ .001); any potential survival benefit of this genotype in patients age Ͼ 65 years was marginal (27% v 16%; P ϭ .33). In multivariable analysis, NPM1-positive/FLT3-ITD-negative genotype remained independently associated with an improved OS in patients age 55 to 65 years (P ϭ .002) but not in those age Ͼ 65 years (P ϭ .82). These results were confirmed in validation analyses examining the NCRI/MRC patients. ConclusionNPM1-positive/FLT3-ITD-negative genotype remains a relatively favorable prognostic factor for patients with AML age 55 to 65 years but not in those age Ͼ 65 years.

The pH-responsive poly(amidoamine)s (PAAs) have been previously described. Whereas ISA23 enhances transfection in vitro and ISA1 promotes the cytosolic delivery of the non-permeant toxins this process shows poor efficiency. The aim of this study was to prepare and evaluate PAA conjugates containing the membrane disrupting peptide melittin (MLT). It was hypothesised that PAA conjugation would reduce the haemolytic activity of MLT at pH 7.4, however, upon delivery to tumours by the EPR effect, the polymer would uncoil in an acidic environment exposing MLT and allowing it to interact with membranes. PAA-MLT conjugates were prepared using MLT as a comonomer together with bis-acryloylpiperazine, 2-methylpiperazine and bis-hydroxyethylethylenediamine (ISA1-like), or bis-acrylamidoacetic acid and 2-methylpiperazine (ISA23-like). The melittin content of the conjugates was 6-19% (w/w). Although ISA1-MLT improved gelonin delivery compared to the parent polymer ISA1 (␣ 13-fold increase) and showed pH-dependent haemolytic activity at a polymer concentration of 0.05 mg/ml, this conjugate also displayed high haemolytic activity at pH 7.4. In contrast, ISA23-MLT like the parent compound ISA23 did not deliver gelonin. However, this conjugate could have potential as a novel polymeric anticancer conjugate due to its lack of haemolytic activity at pH 7.4 and retention of cytotoxicity.

Although the prognostic impact of mutations of FLT3 and NPM1 have been extensively studied in younger patients with acute myeloid leukaemia, less is known in older patients whether treated intensively or non-intensively, or in the context of existing prognostic scores. In 1312 patients 16 and 21%, respectively had an FLT3 and NPM1 mutation. An FLT3 mutation did not affect remission rate in intensively or non-intensively treated patients but was associated with an inferior survival. All patients with an NPM1c mutation had a significantly higher remission rate irrespective of treatment approach but survival was not improved, overall, or in any genotype except as in younger patients, in the FLT3 WT NPM1c mutant subgroup. When incorporated into an established multi-parameter prognostic risk score, the molecular information provided additional prognostic definition in 11% of patients.