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The prospective randomized, placebo-controlled CALGB 10603/RATIFY trial (Alliance) demonstrated a statistically significant overall survival benefit from the addition of midostaurin to standard frontline chemotherapy in a genotypically-defined subgroup of 717 patients with FLT3-mutant acute myeloid leukemia (AML). The risk of death was reduced by 22% on the midostaurin-containing arm. In this post hoc analysis, we analyzed the cumulative incidence of relapse (CIR) on this study and also evaluated the impact of 12 4-week cycles of maintenance therapy. CIR analyses treated relapses and AML deaths as events, deaths from other causes as competing risks, and survivors in remission were censored. CIR was improved on the midostaurin arm (HR = 0.71 (95% CI, 0.54-0.93); p = 0.01), both overall and within European LeukemiaNet 2017 risk classification subsets when post-transplant events were considered in the analysis as events. However, when transplantation was considered as a competing risk, there was overall no significant difference between the risks of relapse on the two randomized arms. Patients still in remission after consolidation with high-dose cytarabine entered the maintenance phase, continuing with either midostaurin or placebo. Analyses were inconclusive in quantifying the impact of the maintenance phase on the overall outcome. In summary, midostaurin reduces the CIR., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited part of Springer Nature.)

In myelodysplastic syndromes (MDS), health-related quality of life (HRQoL) represents a relevant patient-reported outcome, which is essential in individualized therapy planning. Prospective data on HRQoL in lower-risk MDS remain rare. We assessed HRQOL by EQ-5D questionnaire at initial diagnosis in 1690 consecutive IPSS-Low/Int-1 MDS patients from the European LeukemiaNet Registry. Impairments were compared with age- and sex-matched EuroQol Group norms. A significant proportion of MDS patients reported moderate/severe problems in the dimensions pain/discomfort (49.5%), mobility (41.0%), anxiety/depression (37.9%), and usual activities (36.1%). Limitations in mobility, self-care, usual activities, pain/discomfort, and EQ-VAS were significantly more frequent in the old, in females, and in those with high co-morbidity burden, low haemoglobin levels, or red blood cells transfusion need (p < 0.001). In comparison to age- and sex-matched peers, the proportion of problems in usual activities and anxiety/depression was significantly higher in MDS patients (p < 0.001). MDS-related restrictions in the dimension mobility were most prominent in males, and in older people (p < 0.001); in anxiety/depression in females and in younger people (p < 0.001); and in EQ-VAS in women and in persons older than 75 years (p < 0.05). Patients newly diagnosed with IPSS lower-risk MDS experience a pronounced reduction in HRQoL and a clustering of restrictions in distinct dimensions of HRQoL as compared with reference populations.

Currently available data regarding the substrate specificity of the multi-drug resistance (MDR) mechanisms P-glycoprotein (Pgp) and MDR-associated protein (MRP1) for idarubicin are inconclusive. A multiparameter flow cytometry method was developed which allows simultaneous quantitative measurement of total cellular fluorescence and the amount of anthracyclines intercalated into the DNA. Anthracycline DNA intercalation was measured by fluorescence resonance energy transfer (FRET) between Hoechst 33342 and anthracyclines. Daunorubicin and idarubicin accumulation were studied and compared in established cell lines expressing Pgp and MRP1. The data demonstrate that daunorubicin DNA intercalation is affected by both Pgp and MRP1 whereas idarubicin DNA intercalation is affected only by MRP1. MRP1 and Pgp function could be blocked completely by 5 microM PAK 104P, while higher concentrations of verapamil, PSC 833 and cyclosporin A were necessary to attain complete blocking of MRP1 compared to Pgp. Daunorubicin DNA intercalation correlates better with cell survival and is more sensitive at physiological MDR expression as observed in hematopoietic progenitors than daunorubicin levels measured by total cellular fluorescence. In conclusion, idarubicin DNA intercalation is reduced by MRP1 but not by Pgp. PAK-104P is an effective modulator for both Pgp and MRP1 and may further improve idarubicin efficacy.

Mobilized peripheral blood progenitor cells (PBPC) have been shown to differ qualitatively from bone marrow (BM) progenitors. The released progenitor cells are predominantly in G0/G1 and show a relatively high percentage of rhodamine dull cells. Within the BM these last two features are characteristic of the more primitive progenitors. Although the mobilized PB cells can give rise to long-term repopulation and thus contain stem cells, the frequency of stem cells is not much higher if long-term initiating cell (LTC-IC) assays are used. To determine whether quiescent stem cells are selectively released or the low-cycle status of PB progenitors is related to the release from the BM microenvironment, the cell cycle status and rhodamine content in the PB and BM during mobilization were studied and compared with steady-state BM. More differentiated and more primitive progenitors were separated based on differentiation markers and cloned in single cell assay. In mobilized PB 54% of the CD34+ cells (n=5) were rhodamine dull compared to 22% in steady-state BM (P=0.014) [n=6]. The percentage of CD34+ cells in the S/G2M phases of the cell cycle was 2.1% in the mobilized PB (n=11), and 18% in steady-state BM (n=11) [P=0.002]. During mobilization the fraction of cells in the S/G2M phase of the cell cycle was 16% in BM (n=7), similar to steady-state BM (P=0.34). The released progenitors represented a selection of BM progenitors, with significantly more primitive progenitors (CD34+/13+/33dim) and less lymphoid precursors (CD34+/19+). Within the more differentiated CD34+113+/33bright, myelomonocytic precursors, both in PB as well as in BM, the percentage S/G2M was relatively higher than in the CD34+/13+/33dim subfraction: in normal BM: median 18% vs 8% (P=0.006) [n=8]; in mobilized PB 3% vs 2% (P=0.03) [n=10]; and in BM during mobilization 24% vs 7% (P=0.01) [n=6]. The cycle status of mobilized PB progenitors was low both in the primitive and more differentiated subfractions. During the mobilization period the BM progenitors are cycling as in steady-state BM. The low-cycle status of the mobilized PB progenitors may be related to the loss of contact with the micro-environment.

We conducted a prospective, multicenter pilot study of remission induction therapy in patients with poor prognosis MDS and AML evolving from a preceding phase of MDS. Fifty evaluable patients from 15 institutions were treated with one or two remission-induction courses consisting of i.v. idarubicin 12 mg/m2/day on days 1, 2, and 3 combined with a continuous i.v. infusion of cytarabine of 200 mg/m2/day on days 1 to 7. Of the 27 complete remitters (54%), 23 received a consolidation course which was identical to the remission-induction course except for the idarubicin 12 mg/m2 which was given on day 1 only. Fifteen patients received maintenance therapy consisting of six courses of cytarabine 10 mg/m2, s.c. twice daily, for 14 days. Two complete remitters were allografted and five patients received an ABMT. The median survival of all 50 treated patients was 14 months. The median duration of disease-free survival was 11 months with two patients in CR more than 2 years after entering CR. Twenty-four of the 27 remitters have relapsed. Four patients died during remission-induction therapy, but no patient died as a result of persisting hypoplasia. No fatal complications occurred during the consolidation and maintenance courses. Age and stage of disease had no significant impact on CR rate nor on remission duration. The CR rate was significantly (P = 0.03) higher in patients with only normal metaphases compared to patients with cytogenetic abnormalities. The DFS at 2 years was 33 vs 8%, respectively, for patients without or with cytogenetic abnormalities (P = 0.02). This study shows that patients below the age of 60 years with poor risk features are candidates for treatment with combination chemotherapy. A complete remission rate of more than 50% may be expected. Maintaining remission after remission-induction chemotherapy is a difficult issue. Patients not eligible for allogeneic BMT may be treated with intensive post-remission chemotherapy or autologous BMT.

Interphase cytogenetics was used to investigate the clonal origin of bone marrow (BM) cells, peripheral blood (PB) cells, and in vitro cultured progenitor cells of five patients with acute myeloid leukemia (AML) and myelodysplasia (MDS). A new in situ hybridization (ISH) technique was used to examine the origin of the progenitor cells. Two patients with respectively, trisomy 8 and polyploidy as ISH marker were studied both at presentation and during remission. At presentation, the in vitro cultured clusters of both cases appeared diploid. Therefore, despite the abnormal growth patterns, the cultured progenitors could have been residual normal cells. Alternatively, they could have originated from a preleukemic clone with a normal karyotype. In both cases abnormal BM and/or PB cells (less than 6%) were detected with ISH during remission, indicating partially or completely clonal remissions in these patients. Both patients have relapsed. One patient with trisomy 10 as ISH marker was analyzed during myelodysplastic phase and after progression to AML. On both occasions, abnormally appearing clusters were cultured. However, only part of the clusters carried trisomy 10. The presence of a subclone characterized by trisomy 10 and an abnormally growing (pre)leukemic clone without trisomy 10 may explain this observation. Monosomy 1 and 17 were respectively used as ISH markers in two other AML patients. All in vitro cultured clusters carried the numerical abnormality. Long-term liquid cultures of these leukemias were performed for 10-20 days. In both cases, no residual normal clonogenic cells could be detected. Therefore, the selective growth advantage of normal progenitor cells in long-term marrow cultures could not be demonstrated in these two patients with leukemia. This paper illustrates the usefulness of ISH to study the biology of AML at the clonogenic level during preleukemic phase, active disease, remission, and under in vitro culture conditions. It is a sensitive technique which allows individual analysis of large numbers of small aggregates and single cells in culture.

Since in AML differentiation is abnormal but not absent, a hierarchy of stem cells, progenitor cells and more differentiated cells is postulated. The leukemic stem cell might also be characterized by the expression of CD34 and the absence of differentiation markers. Bone marrow samples of 33 AML patients, including 10 patients both at presentation and after relapse, were double labeled for CD34 and CD33. In 14/33 AML less than 1% of the labeled cells were found in the CD34+/33- fraction. After relapse a certain shift towards a more primitive phenotype was observed, but in 4/5 relapsed AML the CD34+/33- fraction remained below 1%. Single cells from the different subfractions were cultured and showed heterogeneous cluster and colony growth in both the CD34-/33+ and CD34+/33+ fraction. More colonies were observed in the CD34+/33- fraction. In AML with a more 'mature' phenotype (low number of CD34+/CD33- cells), highly proliferative myeloid, erythroid and mixed colonies could be cloned exclusively from this small CD34+/33- fraction. In five patients with numerical chromosomal abnormalities all these highly proliferative colonies appeared disomic using in situ hybridization (ISH) with centromeric probes. Based on these data we conclude that the CD34+/33- cell fraction in AML with a more mature immunophenotype (small fraction of cells CD34+/33-) comprise residual normal progenitors, while no primitive leukemic progenitors could be identified.

The bcr-abl oncogene is a fusion gene resulting from a reciprocal translocation which forms the hallmark of chronic myeloid leukemia (CML). Antisense oligonucleotides complementary to the two possible mRNA breakpoints were found to inhibit cell growth of CML patient cells and cell lines, but doubt exists about their specificity. In order to test the specificity, phosphorothioate and 3' phosphorothioate capped antisense BCR-ABL oligonucleotides of different length were used. Stability, cellular uptake of oligonucleotides and effect on cell growth were studied in two CML cell lines, BV173 and LAMA-84. Phosphorothioate antisense BCR-ABL oligonucleotides were most stable, showed the highest uptake and induced cell death in BV173 but not in LAMA-84 cells. We selected the most effective antisense oligonucleotide for further analysis. The BV173 and LAMA-84 cell lines do not express the normal c-abl protein, we therefore used a c-abl specific monoclonal antibody for the detection of p210bcr-abl expression by flow cytometry. Dead cells found after treatment were gated out of analysis. Although BCR-ABL antisense oligonucleotides can induce apoptosis, no reduction of p210bcr-abl levels could be detected in living cells after treatment with antisense oligonucleotides. We conclude that antisense mediated inhibition of translation of mRNA into p210bcr-abl is not the mechanism responsible for the induction of apoptosis in cell line BV173.

The change in phenotype, number and proliferative capacity of peripheral blood hematopoietic progenitors (PBHP) was studied in six patients with multiple myeloma during hematopoietic recovery after mobilization with high-dose cyclophosphamide and GM-CSF or G-CSF. In all six patients the first CD34+ cells appearing in the peripheral blood (PB) after cytoreductive treatment were predominantly CD34+/33- (> 70%). At later stages when leukapheresis procedures were started, the CD34+/33+ cells predominated in five of six patients. In leukapheresis harvests of peripheral blood, and in bone marrow addition of SCF and IL-6 to the culturing medium enhanced the plating efficiency. In peripheral blood an increase from 12 to 22% for CD34+/33+ and from 6 to 14% for CD34+/33- was observed. In normal bone marrow we observed an increase from 15 to 23% for CD34+/33+ and from 7 to 17% for CD34+/33-. Highly proliferative progenitors (>500 cells) in the CD34+/33- fraction appeared to be dependent on the addition of 'stem cell recruiting factors' (SCF and IL-6); in bone marrow the percentage of wells with >500 cells increased from 0.9 to 12.6% after SCF+IL-6 and in PBHP from 2 to 9%. We conclude that the first progenitors appearing in the peripheral blood after priming with high-dose cyclophosphamide and GM- or G-CSF have a more primitive immunophenotype, CD34+/33-.

The effect of growth stimulation on the sensitivity of normal and leukemic human bone marrow progenitors to idarubicin and doxorubicin was studied. Clonogenic assays from colony-forming units of the granulocyte-macrophage lineage (CFU-GM) and leukemic clonogenic cells (CFU-L) were applied using human placenta conditioned medium (HPCM) as source of growth factors. Before seeding cells in clonogenic assay they were exposed to the anthracyclines for 2 h without preincubation, or following a 48 h preincubation period in the presence of HPCM. Drug concentrations used ranged from 0.001-0.1 microgram/ml for idarubicin and from 0.1-1.5 microgram/ml for doxorubicin. In addition, a limited number of bone marrow samples were exposed to the cytostatically active metabolite of idarubicin; idarubicinol (Idol; range 0.001-0.1 microgram/ml). Proliferation of CFU-GM and CFU-L during 48 h was measured by iododeoxyuridine (IdUrd) incorporation. Spontaneous proliferation of CFU-GM increased from 38 to 88% after 48 h stimulation by HPCM. The mean number of proliferating CFU-L increased from 40 to 77% when stimulated with HPCM. Doxorubicin inhibited colony formation of CFU-GM and CFU-L to 50% (IC50CFU-GM, IC50CFU-I) at mean concentrations of 0.355 microgram/ml and 0.103 microgram/ml when applied before preincubation with HPCM, and 0.108 microgram/ml and 0.055 microgram/ml when applied after preincubation. Idarubicin appeared the most potent drug in all experiments regardless of the preincubation procedure or sample origin, with average IC50CFU-GM and IC50CFU-L of 0.008 microgram/ml and 0.006 microgram/ml, respectively, when applied before preincubation with HPCM, and 0.006 microgram/ml and 0.005 microgram/ml when applied after preincubation with HPCM. Idarubicinol showed intermediate potency with average IC50CFU-GM of 0.022 microgram/ml and 0.023 microgram/ml when applied before and after preincubation with HPCM, respectively. In order to assess the effect of growth stimulation on drug sensitivity, samples were evaluated pair-wise (sensitivity of the same sample before vs. after preincubation with HPCM) and were submitted to the Wilcoxon test for matched pairs. Statistically significant enhancement of cytotoxicity was demonstrated for Doxorubicin vs. CFU-GM (p < or = 0.021) and a strong trend versus CFU-L (p = 0.06). The data further demonstrate that proliferation-dependency of doxorubicin toxicity is more pronounced for CFU-GM than for CFU-L. These data also show that idarubicin and idarubicinol toxicity is proliferation-independent. Idarubicin is relatively more potent than doxorubicin in suppressing the growth potential of low or nonproliferating progenitors.(ABSTRACT TRUNCATED AT 400 WORDS)