Late relapse after hematopoietic stem cell transplantation for acute leukemia: a retrospective study by SFGM-TC

Late relapse (LR) after allogeneic hematopoietic stem cell transplantation (AHSCT) for acute leukemia is a rare event (nearly 4.5%) and raises the questions of prognosis and outcome after salvage therapy. We performed a retrospective multicentric study between January 1, 2010, and December 31, 2016, using data from the French national retrospective register ProMISe provided by the SFGM-TC (French Society for Bone Marrow Transplantation and Cellular Therapy). We included patients presenting with LR, defined as a relapse occurring at least 2 years after AHSCT. We used the Cox model to identify prognosis factors associated with LR. During the study period, a total of 7582 AHSCTs were performed in 29 centers, and 33.8% of patients relapsed. Among them, 319 (12.4%) were considered to have LR, representing an incidence of 4.2% for the entire cohort. The full dataset was available for 290 patients, including 250 (86.2%) with acute myeloid leukemia and 40 (13.8%) with acute lymphoid leukemia. The median interval from AHSCT to LR was 38.2 months (interquartile range [IQR], 29.2 to 49.7 months), and 27.2% of the patients had extramedullary involvement at LR (17.2% exclusively and 10% associated with medullary involvement). One-third of the patients had persistent full donor chimerism at LR. Median overall survival (OS) after LR was 19.9 months (IQR, 5.6 to 46.4 months). The most common salvage therapy was induction regimen (55.5%), with complete remission (CR) obtained in 50.7% of cases. Ninety-four patients (38.5%) underwent a second AHSCT, with a median OS of 20.4 months (IQR, 7.1 to 49.1 months). Nonrelapse mortality after second AHSCT was 18.2%. The Cox model identified the following factors as associated with delay of LR: disease status not in first CR at first HSCT (odds ratio [OR], 1.31; 95% confidence interval [CI], 1.04 to 1.64; P = .02) and the use of post-transplantation cyclophosphamide (OR, 2.23; 95% CI, 1.21 to 4.14; P = .01). Chronic GVHD appeared to be a protective factor (OR, .64; 95% CI, .42 to .96; P = .04). The prognosis of LR is better than in early relapse, with a median OS after LR of 19.9 months. Salvage therapy associated with a second AHSCT improves outcome and is feasible, without creating excess toxicity.

Allogeneic stem cell transplantation for patients with mantle cell lymphoma who failed autologous stem cell transplantation: a national survey of the SFGM-TC

Poly-chemotherapy plus rituximab followed by autologous stem cell transplantation (auto-SCT) is standard care for untreated young patients with mantle cell lymphoma (MCL). Despite this intensive treatment, transplant patients remain highly susceptible to relapse over time. The French SFGM-TC performed a national survey on reduced-intensity conditioning allogeneic stem cell transplantation (RIC-allo-SCT) for fit relapsed/refractory patients who failed after auto-SCT (n=106). Median times of relapse after auto-SCT, and from auto-SCT to RIC-allo-SCT were 28 months and 3.6 years, respectively. Sixty per cent of patients received at least three lines of treatment before RIC-allo-SCT. Conditioning regimens for RIC-allo-SCT were heterogeneous. Twenty patients experienced grade III/IV aGvHD, extensive cGvHD was reported in 28 cases. Median follow-up after RIC-allo-SCT was 45 months. Median PFS after RIC-allo-SCT was 30.1 months and median overall survival was 62 months. Treatment-related mortality (TRM) at 1 year and 3 years were estimated at 28% and 32%, respectively. A total of 52 patients died; major causes of death were related to toxicity (n=34) and MCL (n=11). Patients in good response before RIC-allo-SCT experienced a better PFS and OS. Our work highlights the need for new RIC-allo-SCT MCL-tailored approaches to reduce TRM, and early and late relapse.

Comparison of melphalan-prednisone-thalidomide (MP-T) to melphalan-prednisone (MP) in patients 75 years of age or older with untreated multiple myeloma (MM). Preliminary results of the randomized, double-blind, placebo controlled IFM 01–01 trial

8001

Background: The MP-T combination has been shown to be the standard treatment in newly diagnosed MM patients (pts) aged 65 to 75 years (Facon et al; JCO 2006; 24, A1). However, no specific therapeutic recommendation exists for pts older than 75 years regarding the benefit of adding Thalidomide to MP. Methods: The IFM 01–01 trial was initiated in 04/2002. Patients > 75 years with untreated MM were randomized to receive MP (Melphalan 0.2mg/kg/d + Prednisone 2 mg/kg/d day1–4, 12 courses at 6-weeks intervals) + placebo (MP-placebo) vs MP + daily Thalidomide 100mg/d (MP-T). No anti-VTE prophylaxis was given. The primary end-point was overall survival (OS). Secondary end points were progression-free survival (PFS), response to treatment and toxicity. A first interim analysis was performed after the inclusion of 150 patients and a data safety monitoring board recommended a second analysis after the accrual of 200 patients. We here present the preliminary results of this analysis. Results: At the reference date of November 1, 2006, 232 pts were randomised. In all, 200 pts were analysed (100 per group), with 33.5% of pts >80 years (median age, 78.4 years). There were no differences between the 2 groups regarding baseline characteristics. Data were analysed on an intent-to-treat basis. After the completion of therapy the rates of partial response and very good partial response were 31% and 8% respectively with MP-placebo vs 61% and 22% respectively with MP-T. The median PFS time was 19 months (95%-CI 14.6–21.5) with MP-placebo vs 24.1 months (95%-CI 19.4–29.7) with MP-T (p=0.004 log-rank test). In the MP-T arm, 43/100 pts stopped treatment due to toxicity (10 due to neuropathy) versus 11/100 in the MP-placebo arm. Toxicity (Grade 2–4) included peripheral neuropathy (18%), somnolence (7%) and DVT (7%) with MP-T, vs 6%, 6% and 1% respectively, with MP-placebo. Final results including OS data will be presented at the meeting. Conclusion: MPT is an effective combination with acceptable toxicity in patients with MM = 75 years of age, with a significant improvement in PFS.

No significant financial relationships to disclose.

Allogeneic bone marrow transplantation in patients with follicular lymphoma: a single center study

The role of allogeneic BMT for follicular lymphoma remains to be established. From 1995 to 2000, 16 patients with follicular lymphoma underwent allogeneic BMT at our center. At the time of transplantation, two patients were in complete remission, 11 in partial remission and three had refractory disease. Fourteen patients were transplanted using a standard myeloablative conditioning regimen and two a nonmyeloablative conditioning regimen. With a median follow-up of 1184 days (range 403-1999 days) after BMT, 11 patients were alive, whereas five died of transplant-related mortality. Eight patients remained in CR 284+ to 1022+ days (median 560+ days) after BMT. Two patients relapsed 63 and 1073 days after BMT. They achieved a further complete remission after salvage treatment and remained alive 403 and 1224 days after BMT, respectively. One patient with autologous reconstitution had never been in CR after BMT. He was retreated with salvage chemotherapy but only achieved CR with subsequent rituximab treatment and was still alive, 1999 days after transplantation. The estimated 2-year overall survival and event-free survival rates were 68% and 55%, respectively. Age greater than 37 years at diagnosis, positive recipient CMV serology and ECOG performance status > or =1 at diagnosis were associated with shorter overall survival (P = 0.05, P = 0.009 and P = 0.03, respectively). Ann Arbor III-IV stage at diagnosis was associated with shorter event-free survival (P < 0.04). Allogeneic BMT seems to be effective for patients with follicular lymphoma. However, the relatively high rate of early transplant-related mortality emphasizes the need to define indications and use prospective protocols involving a less toxic transplant procedure.

Inhibition of chitin synthetase from Saccharomyces cerevisiae by a new UDP-GlcNAc analogue

The synthesis and biological evaluation of a new UDP-GlcNAc competitor (I), designed to mimic the transition state of the sugar donor in the enzymatic reaction catalysed by chitin synthetase, is described. Compound (I) was found to competitively inhibit chitin synthetase from Saccharomyces cerevisiae with respect to UDP-GlcNAc, but displayed minimal antifungal activity.

Synthesis, mechanism of action, and antiviral activity of a new series of covalent mechanism-based inhibitors of S-adenosyl-L-homocysteine hydrolase

A direct method for the preparation of 5'-S-alkynyl-5'-thioadenosine and 5'-S-allenyl-5'-thioadenosine has been developed. Treatment of a protected 5'-acetylthio-5'-deoxyadenosine with sodium methoxide and propargyl bromide followed by deprotection gave the 5'-S-propargyl-5'-thioadenosine 4. Under controlled base-catalysis with sodium tert-butoxide in tert-butyl alcohol 4 was quantitatively converted into 5'-S-allenyl-5'-thioadenosine 5 or 5'-S-propynyl-5'-thioadenosine 6. Incubation of recombinant human placental AdoHcy hydrolase with 4, 5, or 6 resulted in time- and concentration-dependent inactivation of the enzyme (K(i): 45 +/- 0.5, 16 +/- 1, and 15 +/- 1 microM, respectively). Compound 4 caused complete conversion of the enzyme from its E-NAD(+) to E-NADH form during the inactivation process. This indicates that 4 is a substrate for the 3'-oxidative activity of AdoHcy hydrolase (type I inhibitor). In contrast, the NAD(+)/NADH content of the enzyme was not affected during the inactivation process with 5 and 6, and their mechanism of inactivation was further investigated. Addition of enzyme-sequestered water on the S-allenylthio group of 5 or S-propynylthio group of 6 within the active site should lead to the formation of the corresponding thioester 7. This acylating-intermediate agent could then undergo nucleophilic attack by a protein residue, leading to a type II mechanism-based inactivation. ElectroSpray mass spectra analysis of the inactivated protein by 5 supports this mechanistic proposal. Further studies (MALDI-TOF and ESI/MS(n) experiments) of the trypsin and endo-Lys-C proteolytic cleavage of the fragments of inactivated AdoHcy hydrolase by 5 were carried out for localization of the labeling. The antiviral activity of 4, 5, and 6 against a large variety of viruses was determined. Significant activity (EC(50): 1.9 microM) was noted with 5 against vaccinia virus.

p16(INK4a) and p15(INK4b) gene methylations in plasma cells from monoclonal gammopathy of undetermined significance

p15(INK4b) and p16(INK4a) proteins are cell cycle regulators involved in the inhibition of G1 phase progression. High frequency of methylation of both genes has been reported in multiple myeloma (MM), but it remains to be determined how and when these alterations contribute to tumorigenesis. Monoclonal gammopathy of undetermined significance (MGUS) represents an early disease stage in a fraction of MMs. Plasma cells from 33 patients with MGUS and 33 patients with MM were isolated and analyzed for p15(INK4b) and p16(INK4a) methylation by methylation-specific polymerase chain reaction. Selective methylation was found in 19% for p16(INK4a), 36% for p15(INK4b), and 6.5% for both genes in MGUS, and frequencies were similar in MM suggesting that methylation of these genes is an early event, not associated with transition from MGUS to MM. p15(INK4b) and p16(INK4a) gene methylation might contribute to immortalization of plasma cells rather than malignant transformation in the natural history of MM.

Mechanism of inactivation of S-adenosyl-L-homocysteine hydrolase by 5'-deoxy-5'-S-allenylthioadenosine and 5'-deoxy-5'-S-propynylthioadenosine

5'-Deoxy-5'-S-allenylthioadenosine 1 and 5'-deoxy-5'-S-propnylthioadenosine 2, derived from adenosine, were prepared. 1 and 2 caused irreversible inactivation of AdoHcy hydrolase. ESI mass spectra analysis of the inactivated enzyme demonstrated that 1 and 2 were type II "mechanism-based" inhibitors.

Inactivation of S-adenosyl-L-homocysteine hydrolase with fluorinated analogs of 2'- and 3'-deoxy-5'-methylthioadenosine

Fluorinated analogs of 2'- and 3'-deoxy-5'-methylthioadenosine 1-4 caused irreversible inactivation of AdoHcy hydrolase. Based on the ESI-Mass spectra analysis of the inactivated enzyme with the fluorinated analog 1 a mechanism of inactivation is proposed.

Chromosome 13 abnormalities identified by FISH analysis and serum beta2-microglobulin produce a powerful myeloma staging system for patients receiving high-dose therapy

A careful prognostic evaluation of patients referred for high-dose therapy (HDT) is warranted to identify those who maximally benefit from HDT as well as those who clearly fail current HDT and are candidates for more innovative treatments. In a series of 110 patients with myeloma who received HDT as first-line therapy, times to event (disease progression and death) were studied through proportional hazard models, in relation to different prognostic factors, including a chromosome 13 fluorescence in situ hybridization (FISH) analysis using a D13S319 probe. Delta13 was detected in 42 patients (38%). Follow-up time among surviving patients and survival time were 48 +/- 3 and 51 +/- 7 months, respectively (median +/- SE). In the univariate analysis, Delta13 was the most powerful adverse prognostic factor for all times to event, especially for the survival time (P <.0001) and was followed by beta2-microglobulin (beta2m) levels 2.5 mg/L or higher (P =.0001). The comparison of survival prognostic models including beta2m 2.5 mg/L or greater and another factor favored the Delta13/beta2m combination. In 22 patients (20%) with no unfavorable factor, the median survival time was not reached at 111 months. In contrast, among 55 patients (50%) with one unfavorable factor and 33 patients (30%) with 2 unfavorable factors, median survival times were 47.3 +/- 4.6 months and 25.3 +/- 3.2 months, respectively (P <.0001). We conclude that delta13, adequately detected by FISH analysis, is a very strong factor related to poor survival, especially when associated with a beta2m level of 2.5 mg/L or higher. Routine FISH Delta13 assessment is strongly recommended for patients considered for HDT.

Synthesis of new (difluoromethylphosphono)azadisaccharides designed as bisubstrate analogue inhibitors for GlcNAc:beta-1,4 glycosyltransferases

We report here the design, synthesis and antifungal evaluation of a new model of bisubstrate analogue inhibitor for glycosyltransferases. The synthetic strategy relies on the reductive amination between the aldehyde derived from an N-allylphosphono-pyrrolidine and an aminosugar.

A new series of mechanism-based inhibitors of S-adenosyl-L-homocysteine hydrolase from beef liver

Nucleosides I, II, III caused irreversible inactivation of AdoHcy hydrolase. A mechanism of inactivation is proposed.

On the catalytic mechanism of adenosylhomocysteine/methylthioadenosine nucleosidase from E. coli

AdoHcy/MTA nucleosidase has been under scrutiny in a series of studies to explore its catalytic mechanism.

The mechanism of inactivation of S-adenosylhomocysteine hydrolase by fluorinated analogs of 5'-methylthioadenosine

5'-Deoxy-5'-difluoromethylthioadenosine (DFMTA) 1a and 5'-deoxy-5'-trifluoromethyl-thioadenosine (TFMTA) 1b are inhibitors of beef liver S-adenosyl-L-homocysteine hydrolase. DFMTA and TFMTA are time-dependent and irreversible inhibitors of the enzyme. Both 1a and 1b are oxidized by E-NAD+ to produce E-NADH and fluoride anion is formed in the inactivation reaction (2.2 mol of fluoride/mole of enzyme subunit and 3.1 fluoride/mole of enzyme subunit from DFMTA and TFMTA respectively). Using [8-3H]-1a or [8-3H]-1b no trace of labelled adenosine was detected during the inactivation reaction but adenine was formed. The mechanism of inhibition of S-adenosyl-L-homocysteine hydrolase by these two fluorinated nucleosides is discussed.

The catalytic mechanism of adenosylhomocysteine/methylthioadenosine nucleosidase from Escherichia coli--chemical evidence for a transition state with a substantial oxocarbenium character

The substrate and inhibitory specificity of Escherichia coli adenosylhomocysteine (AdoHcy)/methylthioadenosine (MeSAdo) nucleosidase has been explored with several MeSAdo analogues modified on the sugar moiety at the 2', 3' and 5' positions. Alteration at C3' or at C2' and C3' positions in MeSAdo abolished substrate activity. However, the 2'-deoxy analogue of MeSAdo is effective as a substrate; this result provides evidence against a possible general-base catalysis involving the anchimeric assistance of the 2'-alpha-hydroxy group and the formation of a 1,2-epoxide as an intermediate in the catalytic process. The results of a study of the interaction of an 8,5'-cyclo analogue of MeSAdo with the enzyme indicate the importance of the glycosidic conformation of the substrate for binding to the active site. The enzyme discriminates against methanol attack from the solvent during catalysis. This implies the participation of an enzyme-directed water nucleophile. A poor solvent kinetic deuterium-isotope effect was measured (0.93) on the Vmax. Plots of log Vmax and log (Vmax/Km) for MeSAdo as a function of pH values from 5.0 to 8.5 are similar, with two presumably essential ionisable groups for catalysis with apparent pKa values of 5.6 and 8.2, whereas Km is independent of pH. When the 2'-alpha-hydroxy group of MeSAdo is substituted by fluorine, a significant decrease (28 500-fold) in the Vmax for enzyme-catalysed hydrolysis of the modified substrate is observed. This result indicates a transition state with a substantial oxocarbenium character. From these data, the reaction mechanism for AdoHcy/MeSAdo nucleosidase is discussed.

A new series of S-adenosyl-L-methionine synthetase inhibitors

A new series of epithio and epoxy amino acid analogues of L-methionine or L-methoxinine were examined as potential inhibitors of the enzyme S-adenosylmethionine (AdoMet) synthetase. The kinetic behaviour of these compounds was studied using recombinant rat liver S-adenosyl-L-methionine sythetase (alpha-isoform) fractionated from E. coli, transformed with the plasmid pSSRL-T7N. All the compounds tested were competitive inhibitors with respect to L-methionine and the (2S, 4S)-2-amino-4,5-epoxy pentanoic acid was found to be a very potent inhibitor of the enzyme compared to those already reported for AdoMet synthetase from other mammalian tissues.

A new series of cyclic amino acids as inhibitors of S-adenosyl L-methionine synthetase

Optically active 3-amino-3-(tetrahydrofuranyl) carboxylic acid, 3-amino-3-(tetrahydrothienyl) carboxylic acid and their corresponding six membered ring analogues have been synthesised and examined as potential inhibitors of the enzyme S-adenosylmethionine (AdoMet) synthetase. The kinetic behaviour of these compounds was studied using recombinant rat liver AdoMet synthetase (alpha-isoform) fractionated from E. coli transformed with the plasmid pSSRL-T7N. All the compounds tested were competitive inhibitors of the enzyme with respect to L-methionine.

Methylation of the p15(INK4b) gene in myelodysplastic syndromes is frequent and acquired during disease progression

p15(INK4b) gene is an inhibitor of cyclin-dependent kinase (CDK) 4 and CDK6 whose expression is induced by transforming growth factor (TGF)beta. Recent reports suggest frequent methylation of the p15(INK4b) gene promoter in leukemias, and it has been proposed that this methylation could be necessary for leukemic cells to escape TGF beta regulation. We investigated the methylation status of p15(INK4b) gene in 53 myelodysplastic syndromes (MDS) cases, including nine that had progressed to acute myeloid leukemia (AML), using a recently described sensitive method where polymerase chain reaction (PCR) is preceded by bisulfite modification of DNA (methylation specific PCR). p15(INK4b) methylation was observed in 20 of 53 (38%) of the cases. Twenty of the 24 patients with greater than 10% bone marrow blasts had p15(INK4b) methylation (including all nine patients who had progressed to AML) as compared with none of MDS patients with <10% bone marrow blasts. No correlation between karyotypic abnormalities and methylation status was found. Patients with p15(INK4b) methylation had a worse prognosis, but the prognostic significance of p15(INK4b) methylation was no more found by multivariate analysis, due to its strong correlation to the percentage of marrow blasts. In 10 MDS cases, sequential DNA samples were available. In five of them, methylation of the p15(INK4b) gene was detected at leukemic transformation, but not at diagnosis. Our results showed that methylation of the p15(INK4b) gene in MDS is correlated with blastic bone marrow involvement and increases with disease evolution toward AML. It suggests that proliferation of leukemic cells might require an escape of regulation of the G1 phase of the cell cycle, and possibly of TGF beta inhibitory effect.

The application of low voltge mass spectrometry to the determination of extent and location of deuterium substitution in dethiobiotin

The fragmentation mechanism of dethiobiotin and its derivatives has been studied. A new fragmentation favoured at low energy allows the localization of deuterium on the carbons 2, 3, 4 and 5 in a sample of monodeuterated dethiobiotin.