Blinatumomab + ponatinib for relapsed/refractory Philadelphia chromosome-positive acute lymphoblastic leukemia in adults.

We retrospectively examined the results of a new chemo-free approach combining blinatumomab with ponatinib (blina/pona) in 26 relapsed/refractory Philadelphia positive (Ph+) acute lymphoblastic leukemia (ALL) patients. All but one achieved complete morphologic remission, and 23 achieved a complete molecular response. With a median follow-up of 34.4 months, the median overall (OS) and event-free (EFS) survivals were 20 and 15.3 months, respectively. After blina/pona, 8 patients underwent an allotransplant (allo), while among the 18 non-transplanted cases, 15 received ponatinib in maintenance. Fifteen relapse/progressions occurred with a significant difference between allo and non allo cases (12.5% vs 82.3%, p = 0.003). However, OS and EFS were similar between both groups. Finally, blina/pona was well tolerated with eight reversible neurologic events and three cytokine release syndromes. Prospective studies are needed to properly assess the safety, tolerability and efficacy of the combination therapy.

Late molecular recurrences in patients with chronic myeloid leukemia experiencing treatment-free remission.

Treatment-free remission (TFR) is an opportunity for patients with chronic myeloid leukemia (CML). Reported cumulative incidence curves of molecular recurrence (MRec) arbor a 2-phase shape with mainly early events, but also some late events (late MRec [LMRec]). Having discontinued our first patient in 2004, we have access to a prolonged follow-up, enabling us to characterize these late events. Over 15 years, 128 patients from our institution were registered in the Stop Imatinib (STIM; A Study for Tyrosine Kinase Inhibitors Discontinuation [A-STIM]) trial. MRec was defined by the loss of major molecular response (BCR-ABL1IS >0.1%). At the first TFR attempt, patients had been taking a tyrosine kinase inhibitor for a median of 7.1 years and in BCR-ABL1IS ≤0.01% (MR4) for a median of 4 years. The median follow-up of patients in TFR was 6.5 years. The TFR rate was estimated to be 45.6% after 7 years. For 9/65 (14%) patients experiencing MRec, recurrence occurred after 2 years in TFR (median, 3.6 years). The residual rate of MRec after 2 years was estimated to be 18%. The probability of remaining in TFR was 65.4% for patients having experienced fluctuations of their minimal residual disease (MRD) (at least 2 consecutive measurements BCR-ABL1IS >0.0032% or loss of MR4), whereas it was 100% for those with stable MRD (P = .003). After 2 years in TFR, we observed an 18% residual rate of LMRec. These late events represent 14% of all MRec and occur in patients with fluctuating MRD measurements. A long-term molecular follow-up therefore remains mandatory for CML patients in TFR. The A-STIM study was registered at www.clinicaltrials.gov as #NCT02897245.

Highlighting the Potency of Biosurfactants Produced by Pseudomonas Strains as Anti-Legionella Agents.

Legionella pneumophila, the causative agent of Legionnaires' disease, is a waterborne bacterium mainly found in man-made water systems in close association with free-living amoebae and multispecies biofilms. Pseudomonas strains, originating from various environments including freshwater systems or isolated from hospitalized patients, were tested for their antagonistic activity towards L. pneumophila. A high amount of tested strains was thus found to be active. This antibacterial activity was correlated to the presence of tensioactive agents in culture supernatants. As Pseudomonas strains were known to produce biosurfactants, these compounds were specifically extracted and purified from active strains and further characterized using reverse-phase HPLC and mass spectrometry methods. Finally, all biosurfactants tested (lipopeptides and rhamnolipids) were found active and this activity was shown to be higher towards Legionella strains compared to various other bacteria. Therefore, described biosurfactants are potent anti-Legionella agents that could be used in the water treatment industry although tests are needed to evaluate how effective they would be under field conditions.

Specific Anti-Leukemic Activity of the Peptide Warnericin RK and Analogues and Visualization of Their Effect on Cancer Cells by Chemical Raman Imaging.

Antimicrobial peptides can be used as therapeutic agents against cancer cells. Warnericin RK and derivatives (WarnG20D and WarnF14V) were tested on various, solid tumor or leukemia, cancer cells. These peptides appeared to be cytotoxic on all the cell types tested, cancerous as well healthy, but very interestingly displayed no deleterious effect on healthy mononuclear cells. The mode of action of the peptide was proposed to be membranolytic, using chemical Raman imaging. Addition of peptide induced a large disorganization of the membrane leading to the loss of the content of inner compartments of Jurkat cell, whereas no effect was observed on the healthy mononuclear cells. The less hemolytic peptides WarnG20D and WarnF14V could be good candidates for the leukemia treatment.

Legionella pneumophila: The Paradox of a Highly Sensitive Opportunistic Waterborne Pathogen Able to Persist in the Environment.

Legionella pneumophila, the major causative agent of Legionnaires' disease, is found in freshwater environments in close association with free-living amoebae and multispecies biofilms, leading to persistence, spread, biocide resistance, and elevated virulence of the bacterium. Indeed, legionellosis outbreaks are mainly due to the ability of this bacterium to colonize and persist in water facilities, despite harsh physical and chemical treatments. However, these treatments are not totally efficient and, after a lag period, L. pneumophila may be able to quickly re-colonize these systems. Several natural compounds (biosurfactants, antimicrobial peptides…) with anti-Legionella properties have recently been described in the literature, highlighting their specific activities against this pathogen. In this review, we first consider this hallmark of Legionella to resist killing, in regard to its biofilm or host-associated life style. Then, we focus more accurately on natural anti-Legionella molecules described so far, which could provide new eco-friendly and alternative ways to struggle against this important pathogen in plumbing.

New therapeutic approaches in myelodysplastic syndromes: Hypomethylating agents and lenalidomide.

Recent advances in the treatment of myelodysplastic syndromes have come from the use of the hypomethylating agents decitabine and azacitidine as well as the immunomodulatory drug lenalidomide. Their clinical benefit has been demonstrated by randomized phase III clinical trials, mostly in high-risk and del(5q) myelodysplastic syndromes, respectively. Neither drug, however, appears to eradicate myelodysplastic stem cells, and thus they currently do not represent curative options. Here, we review data from both clinical and translational research on those drugs to identify their molecular and cellular mechanisms of action and to delineate paths for improved treatment allocation and further therapeutic advances in myelodysplastic syndromes.

Effect of amino acid substitution in the staphylococcal peptides warnericin RK and PSMα on their anti-Legionella and hemolytic activities.

Warnericin RK from Staphylococcus warneri and PSMα from Staphylococcus epidermidis are anti-Legionella peptides which were differently classified in a previous study according to their mode of action. Indeed, warnericin RK is highly hemolytic with a bactericidal mode of action, whereas PSMα is poorly hemolytic with a bacteriostatic mode of action toward L. pneumophila. In order to find anti-Legionella peptides which are not hemolytic, a collection of peptides varying in sequence from warnericin RK to PSMα were designed and synthesized, and their anti-Legionella activities, in terms of growth inhibition, permeabilization, and bactericidal effect, as well as their hemolytic activities, were measured and compared. The results showed that some residues, at position 14 for both peptides for instance, were of major importance for bactericidal and hemolytic activities.

Surfactin from Bacillus subtilis displays an unexpected anti-Legionella activity.

A contaminant bacterial strain was found to exhibit an antagonistic activity against Legionella pneumophila, the causative agent of Legionnaires' disease. The bacterial strain was identified as a Bacillus subtilis and named B. subtilis AM1. PCR analysis revealed the presence of the sfp gene, involved in the biosynthesis of surfactin, a lipopeptide with versatile bioactive properties. The bioactive substances were extracted from AM1 cell-free supernatant with ethyl acetate and purified using reversed phase HPLC (RP-HPLC). Subsequent ESI-MS analyses indicated the presence of two active substances with protonated molecular ions at m/z 1008 and 1036 Da, corresponding to surfactin isoforms. Structures of lipopeptides were further determined by tandem mass spectrometry and compared to the spectra of a commercially available surfactin mixture. Surfactin displays an antibacterial spectrum almost restricted to the Legionella genus (MICs range 1-4 µg/mL) and also exhibits a weak activity toward the amoeba Acanthamoeba castellanii, known to be the natural reservoir of L. pneumophila. Anti-biofilm assays demonstrated that 66 µg/mL of surfactin successfully eliminated 90 % of a 6-day-old biofilm. In conclusion, this study reveals for the first time the potent activity of surfactin against Legionella sp. and preformed biofilms thus providing new directions toward the use and the development of lipopeptides for the control of Legionella spread in the environment.

Genetic variations creating microRNA target sites in the FXN 3'-UTR affect frataxin expression in Friedreich ataxia.

Friedreich's ataxia (FRDA) is a severe neurodegenerative disease caused by GAA repeat expansion within the first intron of the frataxin gene. It has been suggested that the repeat is responsible for the disease severity due to impaired transcription thereby reducing expression of the protein. However, genotype-phenotype correlation is imperfect, and the influence of other gene regions of the frataxin gene is unknown. We hypothesized that FRDA patients may harbor specific regulatory variants in the 3'-UTR. We sequenced the 3'-UTR region of the frataxin gene in a cohort of 57 FRDA individuals and 58 controls. Seven single nucleotide polymorphisms (SNPs) out of 19 were polymorphic in our case-control sample. These SNPs defined several haplotypes with one reaching 89% of homozygosity in patients versus 24% in controls. In another cohort of 47 FRDA Reunionese patients, 94% patients were found to be homozygous for this haplotype. We found that this FRDA 3'-UTR conferred a 1.2-fold decrease in the expression of a reporter gene versus the alternative haplotype configuration. We established that differential targeting by miRNA could account for this functional variability. We specifically demonstrated the involvement of miR-124 (i.e hsa-mir-124-3p) in the down-regulation of FRDA-3'-UTR. Our results suggest for the first time that post-transcriptional regulation of frataxin occurs through the 3'-UTR and involves miRNA targeting. We propose that the involvement of miRNAs in a FRDA-specific regulation of frataxin may provide a rationale to increase residual levels of frataxin through miRNA-inhibitory molecules.