Clonal selection in therapy-related myelodysplastic syndromes and acute myeloid leukemia under azacitidine treatment.

INTRODUCTION: Therapy-related myelodysplastic syndrome and acute myeloid leukemia (t-MDS/AML) are defined as complications of previous cytotoxic therapy. Azacitidine (AZA), a hypomethylating agent, has showed activity in t-MDS/AML. OBJECTIVES: We evaluated the clonal dynamics of AZA-treated t-MDS/AML. METHODS: We collected bone marrow samples, at diagnosis and during treatment, from AZA-treated t-MDS/AML patients. NGS on 19 myeloid genes was performed, and candidate mutations with a variant allele frequency >5% were selected. RESULTS: Seven t-AML and 12 t-MDS were included with median age of 71 (56-82) years old, median number of AZA cycles of 6 (1-15), and median overall survival (OS) of 14 (3-29) months. We observed correlation between AZA response and clonal selection. Decrease of TP53-mutated clone was correlated with response to AZA, confirming AZA efficacy in this subgroup. In some patients, emergence of mutations was correlated with progression or relapse without impact on OS. Clones with mutations in genes for DNA methylation regulation frequently occurred with other mutations and remained stable during AZA treatment, independent of AZA response. CONCLUSION: We confirmed that the molecular complexity of t-MNs and that the follow-up of clonal selection during AZA treatment could be useful to define treatment combination.

Monosomal karyotype improves IPSS-R stratification in MDS and AML patients treated with Azacitidine.

IPSS-R classifies cytogenetic abnormalities into five prognostic groups for survival. Monosomal karyotype (MK) is not a subgroup of IPSS-R. Additional prognostic information from MK in poor and very poor karyotype has been recently shown. The aim of our study was to determine the prognostic value of IPSS-R and MK for response and survival in AZA-treated high-risk MDS and AML with 20-30% of blasts patients. The study population included 154 patients who were classified according to IPSS-R. IPSS-R was not predictive of response (intermediate, 64%; poor, 44%; very poor, 56%; P = 0.28) or survival (intermediate, 25 months; poor, 12 months; very poor, 11 months; P = 0.14). Twenty-one patients (15%) presented with MK and had a median OS of 9 months. Patients with a very high IPSS-R score without MK had a median OS of 15 months, while patients with a high IPSS-R score without MK had a median OS of 13 months (P = 0.18). We reclassified patients into the following three groups to include MK status: very high (MK only; OS median: 9 months), high (very high IPSS-R without MK and high IPSS-R without MK; OS median: 14 months) and intermediate (OS median: 25 months). As in recent publication including MK prognostic, we confirmed that this classification was predictive for survival in AZA treated patients (P = 0.008). IPSS-R failed to discriminate between the prognostic subgroups. Stratification with MK has value in the prognosis of our cohort of AZA-treated patients.

Treatment of myelodysplastic syndromes with excess of blasts by bevacizumab is well tolerated and is associated with a decrease of VEGF plasma level.

Myelodysplastic syndromes (MDS) are associated with increased bone marrow vascularity and increased levels of various angiogenic factors including Vascular Endothelial Growth Factor (VEGF) which is implicated in the proliferation and survival of leukemic cells. Before the approval of hypomethylating agents in this indication, the GFM conducted a multicenter phase II trial testing the efficacy and tolerance of bevacizumab, a humanized monoclonal antibody against VEGF, in MDS with excess of marrow blasts and its impact on bone marrow angiogenesis. Twenty-one patients were enrolled (16 males and five females) with a median age of 70 years and 19 were evaluable for haematological response after treatment (5 mg/kg IV every 2 weeks for 12 weeks). WHO diagnosis at baseline was RAEB-1 (38%) and RAEB-2 (62%). Treatment was well tolerated and was associated with significant decrease of VEGF plasma level [median (low quartile-high quartile)] from 65.5 pg/ml [LQ (low-quartile)-HQ (high quartile), 35.3-87.3 to 30.4 pg/ml (LQ-HQ, 22.5-34.0 pg/ml)] (p < 0.01) and reduction of bone marrow angiogenesis from a median of 20 vessels/mm(3) (LQ-HQ, 16.5-33 vessels/mm(3)) to 15.5 vessels/mm(3) (LQ-HQ, 10-23.2 vessels/mm(3)) (p = 0.03). On the other hand, only one patient had a significant haematological response with achievement of RBC transfusion independence. Thus, although bevacizumab had a significant impact on VEGF levels and angiogenesis in our patients, very few responses were seen when this drug was used as single agent. Given its good tolerability profile, however, combination of bevacizumab with other drugs, especially hypomethylating agents, could be considered in MDS.

Retraction Note: LAMP2 expression dictates azacytidine response and prognosis in MDS/AML.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Analysis of a cohort of 279 patients with hairy-cell leukemia (HCL): 10 years of follow-up.

In total, 279 patients with hairy-cell leukemia (HCL) were analyzed, with a median follow-up of 10 years. Data were collected up to June 2018. We analyzed responses to treatment, relapses, survival, and the occurrence of second malignancies during follow-up. The median age was 59 years. In total, 208 patients (75%) were treated with purine analogs (PNAs), either cladribine (159) or pentosatin (49), as the first-line therapy. After a median follow-up of 127 months, the median overall survival was 27 years, and the median relapse-free survival (RFS) was 11 years. The cumulative 10-year relapse incidence was 39%. In patients receiving second-line therapy, the median RFS was 7 years. For the second-line therapy, using the same or another PNA was equivalent. We identified 68 second malignancies in 59 patients: 49 solid cancers and 19 hematological malignancies. The 10-year cumulative incidences of cancers, solid tumors, and hematological malignancies were 15%, 11%, and 5.0%, respectively, and the standardized incidence ratios were 2.22, 1.81, and 6.67, respectively. In multivariate analysis, PNA was not a risk factor for second malignancies. HCL patients have a good long-term prognosis. PNAs are the first-line treatment. HCL patients require long-term follow-up because of their relatively increased risk of second malignancies.

LAMP2 expression dictates azacytidine response and prognosis in MDS/AML.

Chaperone-mediated autophagy (CMA) is a highly selective form of autophagy. During CMA, the HSC70 chaperone carries target proteins endowed with a KFERQ-like motif to the lysosomal receptor LAMP2A, which then translocate them into lysosomes for degradation. In the present study, we scrutinized the mechanisms underlying the response and resistance to Azacytidine (Aza) in MDS/AML cell lines and bone marrow CD34+ blasts from MDS/AML patients. In engineered Aza-resistant MDS cell lines and some AML cell lines, we identified a profound defect in CMA linked to the absence of LAMP2A. LAMP2 deficiency was responsible for Aza resistance and hypersensitivity to lysosome and autophagy inhibitors. Accordingly, gain of function of LAMP2 in deficient cells or loss of function in LAMP2-expressing cells rendered them sensitive or resistant to Aza, respectively. A strict correlation was observed between the absence of LAMP2, resistance to Aza and sensitivity to lysosome inhibitors. Low levels of LAMP2 expression in CD34+ blasts from MDS/AML patients correlated with lack of sensitivity to Aza and were predictive of poor overall survival. We propose that CD34+/LAMP2Low patients at diagnosis or who become CD34+/LAMP2Low during the course of treatment with Aza might benefit from a lysosome inhibitor already used in the clinic.

BCL2L10 positive cells in bone marrow are an independent prognostic factor of azacitidine outcome in myelodysplastic syndrome and acute myeloid leukemia.

Azacitidine (AZA), the reference treatment for most higher-risk myelodysplastic (MDS) patients can also improve overall survival (OS) in elderly acute myeloid leukemia (AML) patients ineligible for intensive chemotherapy, but reliable biological markers predicting response and OS in patients treated with AZA are lacking. In a preliminary study, we found that an increase of the percentage of BCL2L10, an anti-apoptotic member of the bcl-2 family, was correlated with AZA resistance. In this study, we assessed prospectively by flow cytometry the prognostic value of BCL2L10 positive bone marrow mononuclear cells in 70 patients (42 MDS and 28 AML), prior to AZA treatment.In patients with baseline marrow blasts below 30%, the baseline percentage of bone marrow BCL2L10 positive cells inversely correlated with response to AZA and OS independently of the International Prognostic Scoring System (IPSS) and IPSS-revised (IPSS-R). Specifically, OS was significantly lower in patients with more than 10% BCL2L10 positive cells (median 8.3 vs 22.9 months in patients with less than 10% positivity, p = 0,001). In summary, marrow BCL2L10 positive cells may be a biomarker for azacitidine response and OS, with a potential impact in clinical practice.

BCL-B (BCL2L10) is overexpressed in patients suffering from multiple myeloma (MM) and drives an MM-like disease in transgenic mice.

Multiple myeloma (MM) evolves from a premalignant condition known as monoclonal gammopathy of undetermined significance (MGUS). However, the factors underlying the malignant transformation of plasmocytes in MM are not fully characterized. We report here that Eµ-directed expression of the antiapoptotic Bcl-B protein in mice drives an MM phenotype that reproduces accurately the human disease. Indeed, with age, Eµ-bcl-b transgenic mice develop the characteristic features of human MM, including bone malignant plasma cell infiltration, a monoclonal immunoglobulin peak, immunoglobulin deposit in renal tubules, and highly characteristic bone lytic lesions. In addition, the tumors are serially transplantable in irradiated wild-type mice, underlying the tumoral origin of the disease. Eµ-bcl-b plasmocytes show increased expression of a panel of genes known to be dysregulated in human MM pathogenesis. Treatment of Eµ-bcl-b mice with drugs currently used to treat patients such as melphalan and VELCADE efficiently kills malignant plasmocytes in vivo. Finally, we find that Bcl-B is overexpressed in plasmocytes from MM patients but neither in MGUS patients nor in healthy individuals, suggesting that Bcl-B may drive MM. These findings suggest that Bcl-B could be an important factor in MM disease and pinpoint Eµ-bcl-b mice as a pertinent model to validate new therapies in MM.

Phenotypic and genotypic characterization of azacitidine-sensitive and resistant SKM1 myeloid cell lines.

In the present study, we provide a comparative phenotypic and genotypic analysis of azacitidine-sensitive and resistant SKM-1 cell lines. Morphologically, SKM1-R exhibited increase in cell size that accounts for by enhanced ploidy in a majority of cells as shown by cell cycle and karyotype analysis. No specific Single Nucleotide Polymorphism (SNP) alteration was found in SKM1-R cells compared to their SKM1-S counterpart. Comparative pangenomic profiling revealed the up-regulation of a panel of genes involved in cellular movement, cell death and survival and down-regulation of genes required for cell to cell signaling and free radical scavenging in SKM1-R cells. We also searched for mutations frequently associated with myelodysplastic syndromes (MDS) and found that both cell lines harbored mutations in TET2, ASLX1 and TP53. Collectively, our data show that despite their different morphological and phenotypic features, SKM1-S and SKM1-R cells exhibited similar genotypic characteristics. Finally, pangenomic profiling identifies new potential pathways to be targeted to circumvent AZA-resistance. In conclusion, SKM1-R cells represent a valuable tool for the validation of new therapeutic intervention in MDS.

BCL2L10 is a predictive factor for resistance to azacitidine in MDS and AML patients.

Azacitidine is the leading compound to treat patients suffering myelodysplastic syndrome (MDS) or AML with less than 30% of blasts, but a majority of patients is primary refractory or rapidly relapses under treatment. These patients have a drastically reduced life expectancy as compared to sensitive patients. Therefore identifying predictive factors for AZA resistance is of great interest to propose alternative therapeutic strategies for non-responsive patients. We generated AZA-resistant myeloid cell line (SKM1-R) that exhibited increased expression of BCL2L10 an anti-apoptotic Bcl-2 member. Importantly, BCL2L10 knockdown sensitized SKM1-R cells to AZA effect suggesting that increased BCL2L10 expression is linked to AZA resistance in SKM1-R. We next established in 77 MDS patients that resistance to AZA is significantly correlated with the percentage of MDS or AML cells expressing BCL2L10. In addition, we showed that the proportion of BCL2L10 positive bone marrow cells can predict overall survival in MDS or AML patients. We propose a convenient assay in which the percentage of BCL2L10 expressing cells as assessed by flow cytometry is predictive of whether or not a patient will become resistant to AZA. Therefore, systematic determination of BCL2L10 expression could be of great interest in newly diagnosed and AZA-treated MDS patients.

All tyrosine kinase inhibitor-resistant chronic myelogenous cells are highly sensitive to ponatinib.

The advent of tyrosine kinase inhibitor (TKI) therapy has considerably improved the survival of patients suffering chronic myelogenous leukemia (CML). Indeed, inhibition of BCR-ABL by imatinib, dasatinib or nilotinib triggers durable responses in most patients suffering from this disease. Moreover, resistance to imatinib due to kinase domain mutations can be generally circumvented using dasatinib or nilotinib, but the multi-resistant T315I mutation that is insensitive to these TKIs, remains to date a major clinical problem. In this line, ponatinib (AP24534) has emerged as a promising therapeutic option in patients with all kinds of BCR-ABL mutations, especially the T315I one. However and surprisingly, the effect of ponatinib has not been extensively studied on imatinib-resistant CML cell lines. Therefore, in the present study, we used several CML cell lines with different mechanisms of resistance to TKI to evaluate the effect of ponatinib on cell viability, apoptosis and signaling. Our results show that ponatinib is highly effective on both sensitive and resistant CML cell lines, whatever the mode of resistance and also on BaF3 murine B cells carrying native BCR-ABL or T315I mutation. We conclude that ponatinib could be effectively used for all types of TKI-resistant patients.