Cooperative Sulfur Transformations at a Dinickel Site: A Metal Bridging Sulfur Radical and Its H-Atom Abstraction Thermochemistry.

Starting from the dinickel(II) dihydride complex [ML(Ni-H)2] (1M), where L3- is a bis(tridentate) pyrazolate-bridged bis(ß-diketiminato) ligand and M+ is Na+ or K+, a series of complexes [KLNi2(S2)] (2K), [MLNi2S] (3M), [LNi2(SMe)] (4), and [LNi2(SH)] (5) has been prepared. The µ-sulfido complexes 3M can be reversibly oxidized at E1/2 = -1.17 V (in THF; vs Fc+/Fc) to give [LNi2(S•)] (6) featuring a bridging S-radical. 6 has been comprehensively characterized, including by X-ray diffraction, SQUID magnetometry, EPR and XAS/XES spectroscopies, and DFT calculations. The pKa of the µ-hydrosulfido complex 5 in THF is 30.8 ± 0.4, which defines a S-H bond dissociation free energy (BDFE) of 75.1 ± 1.0 kcal mol-1. 6 reacts with H atom donors such as TEMPO-H and xanthene to give 5, while 5 reacts with 2,4,6-tri(tert-butyl)phenoxy radical in a reverse H atom transfer to generate 6. These findings provide the first full characterization of a genuine M-(µ-S•-)-M complex and provide insights into its proton-coupled electron transfer (PCET) reactivity, which is of interest in view of the prominence of M-(µ-SH/µ-S)-M units in biological systems and heterogeneous catalysis.

Elotuzumab plus pomalidomide and dexamethasone in relapsed/refractory multiple myeloma: a multicenter, retrospective, real-world experience with 200 cases outside of controlled clinical trials.

In the ELOQUENT-3 trial, the combination of elotuzumab, pomalidomide and dexamethasone (EloPd) proved to have a superior clinical benefit over pomalidomide and dexamethasone with a manageable toxicity profile, leading to its approval for the treatment of patients with relapsed/refractory multiple myeloma (RRMM) who have received at least two prior therapies, including lenalidomide and a proteasome inhibitor. We report here a real-world experience of 200 cases of RRMM treated with EloPd in 35 Italian centers outside of clinical trials. In our dataset, the median number of prior lines of therapy was two, with 51% of cases undergoing autologous stem cell transplant and 73% having been exposed to daratumumab. After a median follow-up of 9 months, 126 patients had stopped EloPd, most of them (88.9%) because of disease progression. The overall response rate was 55.4%, a finding in line with the pivotal trial results. Regarding adverse events, the toxicity profile in our cohort was similar to that in the ELOQUENT-3 trial, with no significant differences between younger (<70 years) and older patients. The median progression-free survival was 7 months, which was shorter than that observed in ELOQUENT-3, probably because of the different clinical characteristics of the two cohorts. Interestingly, International Staging System stage III disease was associated with worse progression-free survival (hazard ratio=2.55). Finally, the median overall survival of our series was shorter than that observed in the ELOQUENT-3 trial (17.5 vs. 29.8 months). In conclusion, our real-world study confirms that EloPd is a safe and possible therapeutic choice for patients with RRMM who have received at least two prior therapies, including lenalidomide and a proteasome inhibitor.

Ibrutinib as first line therapy in chronic lymphocytic leukemia patients over 80 years old: A retrospective real-life multicenter Italian cohort.

Although chronic lymphocytic leukemia (CLL) predominantly affects the elderly, limited data exists about the outcomes of over 80-year-old patients, usually underrepresented in clinical trials. We conducted a multicenter study enrolling 79 consecutive CLL patients ≥80 years at the time of frontline therapy, all treated with ibrutinib. Nearly 48% of cases exhibited unmutated IGHV genes, 32% 17p deletion, and 39.2% TP53 mutations; 63.3% displayed a cumulative illness rating scale (CIRS) > 6. The overall response rate on ibrutinib, computed in 74/79 patients (5 patients excluded for early withdrawal), was 89.9%. After a median follow-up of 28.9 months, the median progression-free survival (PFS) and overall survival (OS) were 42.5 and 51.8 months, respectively. CIRS>6 and temporary discontinuation of ibrutinib lasting for 7-30 days were the only parameters associated with a significantly shorter PFS and were both relevant in predicting a shorter PFS compared to patients with CIRS≤6 and therapy discontinuation ≤7 days. The most common grade≥3 adverse events were infections (25.5%), neutropenia (10.1%), and anemia (2.5%). Eighteen patients (22.8%) experienced a cardiovascular event, including grade-2 atrial fibrillation (n = 9; 11%), grade-2 hypertension (n = 5; 6%), heart failure (n = 3; 3%), and acute coronary syndrome (n = 1; 1%). Mild bleeding events were observed in 27 patients (34.2%). Ibrutinib was permanently discontinued in 26 patients due to progressive disease (n = 11, including 5 Richter's syndromes), secondary malignancies (n = 6), infections (n = 3), cardiac failure (n = 3), severe bleeding (n = 2), and sudden death (n = 1). In conclusion, our analyses confirmed the overall effectiveness and favorable safety profile of the ibrutinib-single agent therapeutic approach in CLL patients ≥80 years.

Cobalt Corroles as Electrocatalysts for Water Oxidation: Strong Effect of Substituents on Catalytic Activity.

Two Co(III) complexes (1Py2 and 2Py2) of new corrole ligands H3L1 (5,15-bis(p-methylcarboxyphenyl)-10-(o-methylcarboxyphenyl)corrole) and H3L2 (5,15-bis(p-nitrophenyl)-10-(o-methylcarboxyphenyl)corrole) with two apical pyridine ligands have been synthesized and thoroughly characterized by cyclic voltammetry, UV-vis-NIR, and EPR spectroscopy, spectroelectrochemistry, single-crystal X-ray diffraction studies, and DFT methods. Complexes 1Py2 and 2Py2 possess much lower oxidation potentials than cobalt(III)-tris-pentafluorophenylcorrole (Co(tpfc)) and similar corroles containing pentafluorophenyl (C6F5) substituents, thus allowing access to high oxidation states of the former metallocorroles using mild chemical oxidants. The spectroscopic (UV-vis-NIR and EPR) and electronic properties of several oxidation states of these complexes have been determined by a combination of the mentioned methods. Complexes 1Py2 and 2Py2 undergo three oxidations within 1.3 V vs FcH+/FcH in MeCN, and we show that both complexes catalyze water oxidation in an MeCN/H2O mixture upon the third oxidation, with kobs (TOF) values of 1.86 s-1 at 1.29 V (1Py2) and 1.67 s-1 at 1.37 V (2Py2). These values are five times higher than previously reported TOF values for C6F5-substituted cobalt(III) corroles, a finding we ascribe to the additional charge in the corrole macrocycle due to the increased oxidation state. This work opens up new possibilities in the study of metallocorrole water oxidation catalysts, particularly by allowing spectroscopic probing of high-oxidation states and showing strong substituent-effects on catalytic activity of the corrole complexes.

Mono-, Di- and Tetra-iron Complexes with Selenium or Sulphur Functionalized Vinyliminium Ligands: Synthesis, Structural Characterization and Antiproliferative Activity.

A series of diiron/tetrairon compounds containing a S- or a Se-function (2a-d, 4a-d, 5a-b, 6), and the monoiron [FeCp(CO){SeC1(NMe2)C2HC3(Me)}] (3) were prepared from the diiron µ-vinyliminium precursors [Fe2Cp2(CO)( µ-CO){ µ-η1: η3-C3(R')C2HC1N(Me)(R)}]CF3SO3 (R = R' = Me, 1a; R = 2,6-C6H3Me2 = Xyl, R' = Ph, 1b; R = Xyl, R' = CH2OH, 1c), via treatment with S8 or gray selenium. The new compounds were characterized by elemental analysis, IR and multinuclear NMR spectroscopy, and structural aspects were further elucidated by DFT calculations. The unprecedented metallacyclic structure of 3 was ascertained by single crystal X-ray diffraction. The air-stable compounds (3, 4a-d, 5a-b, 6) display fair to good stability in aqueous media, and thus were assessed for their cytotoxic activity towards A2780, A2780cisR, and HEK-293 cell lines. Cyclic voltammetry, ROS production and NADH oxidation studies were carried out on selected compounds to give insights into their mode of action.

Reductive Binding and Ligand-Based Redox Transformations of Nitrosobenzene at a Dinickel(II) Core.

The metal-mediated activation of PhNO represents an important starting point for understanding the reactivity patterns of nitrosoarenes in biological systems and catalysis. Here we report that the pyrazole-based dinickel(II) dihydride complex [KL(NiH)2] (1) reacts with PhNO to eliminate dihydrogen concomitant with binding of the doubly reduced substrate in µ-κ(O):κ(N) mode in the bimetallic pocket of [KLNi2(PhNO)] (2). The addition of [2,2,2]cryptand leads to the ionic complex [K(crypt)][LNi2(PhNO)] (3). Structural and spectroscopic analyses evidence that interaction with the Lewis acidic K+ in 2 causes significant elongation and weakening of the substrate's N-O bond [ dN-O = 1.487(12) Å in 2 vs 1.374(4) Å in 3]. Complex 2 (or 3) reacts with [FeCp*2][PF6] to give LNi2(PhNO) (4), which is shown by electron paramagnetic resonance and IR spectroscopies and density functional theory calculations to feature two low-spin d8 nickel(II) ions and a bridging (PhNO)•- radical anion ligand, with the out-of-plane π*(NO) being the singly occupied molecular orbital. Cyclic voltammetry and UV-vis spectroelectrochemical experiments show that 4 and the anion of 3 can be reversibly interconverted at very low potential ( E1/2 = -1.53 V vs Fc/Fc+). Protonation of 2 leads to the N-phenylhydroxylamine complex [LNi2(ONHPh)] (5) with a long N-O bond of 1.464(2) Å, and titration studies suggest a p Ka of around 23-25 in tetrahydrofuran. This allows one to derive a bond dissociation energy of 62-65 kcal mol-1 for the N-H bond of 5. Accordingly, 5 readily reacts with the phenoxy radical 2,4,6- tBu3C6H2O• to yield 4. This work demonstrates the reductive binding of PhNO without prior formation of unstable nickel(I) species and the redox noninnocence of the PhNO ligand in the less common µ-κ(O):κ(N) bridging mode. Thermodynamic data for H-atom-abstraction chemistry at the activated PhNO may be valuable for understanding the reactivity patterns of the transient but biologically relevant nitroxyl (HNO) ligand.

Reductive Nitric Oxide Coupling at a Dinickel Core: Isolation of a Key cis-Hyponitrite Intermediate en route to N2 O Formation.

Reductive coupling of nitric oxide (NO) to give N2 O is an important reaction in the global nitrogen cycle. Here, a dinickel(II) dihydride complex 1 that releases H2 upon substrate binding and serves as a masked dinickel(I) scaffold is shown to reductively couple two molecules of NO within the bimetallic cleft. The resulting hyponitrite complex 2 features an unprecedented cis-[N2 O2 ]2- binding mode that has been computationally proposed as a key intermediate in flavodiiron nitric oxide reductases (FNORs). NMR and DFT evidence indicate facile rotational fluxionality of the [N2 O2 ]2- unit, which allows to access an isomer that is prone to N2 O release. Protonation of 2 is now found to trigger rapid N2 O evolution and formation of a hydroxido bridged complex, reminiscent of FNOR reactivity. This work provides fundamental insight into the biologically relevant reductive coupling of two NO molecules and the subsequent trajectory towards N2 O formation at bimetallic sites.

Coordination Compounds of Niobium(IV) Oxide Dihalides Including the Synthesis and the Crystallographic Characterization of NHC Complexes.

The 1:1 molar reactions of NbOX3 with SnBu3H, in toluene at 0 °C in the presence of oxygen/nitrogen donors, resulted in the formation of NbOX2L2 (X = Cl, L2 = dme, 2a; X = Br, L2 = dme, 2b; X = Cl, L = thf, 2c; X = Cl, L = NCMe, 2d; dme = 1,2-dimethoxyethane, thf = tetrahydrofuran), in good yields. The 1:2 reactions of freshly prepared 2d and 2b with the bulky NHC ligands 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene, Imes, and 1,3-bis(2,6-dimethylphenyl)imidazol-2-ylidene, Ixyl, respectively, afforded the complexes NbOCl2(Imes)2, 3, and NbOBr2(Ixyl)2, 4, in 50-60% yields. The reactions of 2b with NaOR, in tetrahydrofuran, gave NbOCl(OR) (R = Ph, 5; R = Me, 6) in about 60% yields. All the products were characterized by analytical and spectroscopic techniques; moreover DFT calculations were carried out in order to shed light on synthetic and structural features. Compounds 3 and 4, whose molecular structures have been ascertained by X-ray diffraction, represent very rare examples of crystallographically characterized niobium-NHC systems.

The role of clinical trials in the sustainability of the Italian national health service cancer drug expenditure.

OBJECTIVE: Clinical trials offer new and potentially more effective therapeutic options for cancer patients and a potential cost-saving opportunity, especially considering that trial drugs are provided free-of-charge. The aim of this study was to analyse drug-related cost savings in clinical trials in a cancer institute over a 3 year period. The cost savings relate to the pharmaceutical expenditure of our centre, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) "Dino Amadori". METHODS: We conducted a retrospective analysis of patients taking part in interventional clinical cancer trials approved by a local independent Ethics Committee between 1 January 2018 and 31 December 2020. The standard of care (SOC) was identified as the standard treatment that would have been offered to a patient if he/she had not been enrolled in the study. The sum of SOC costs of all patients represents the potential cost avoidance during the study period. Results were stratified by year, trial promoter, trial phase and tumour type. The same approach was used to perform a secondary analysis of compassionate use programmes. RESULT: In the 3 year analysis, 1,257 patients were treated with experimental therapies in 244 clinical trials, of which 157 were profit and 87 academic. Results showed an overall cost savings of €13,266,518, more than 50% of which (€7,035,009) was related to phase III studies. Profit clinical trials generated €9,069,764 (68.4%) of the drug cost savings compared with €4,196,754 (31.6%) of academic studies. The stratification for tumour type was €3,552,592 (26.8%) genitourinary cancer, €3,268,074 (24.6%) melanoma, €2,574,127 (19.4%) haematological malignancies, €2,330,791 (17.6%) lung cancer, €728,149 (5.5%) gastrointestinal cancer, €557,608 (4.2%) rare tumours and €255,178 (1.9%) breast cancer. The secondary analysis on compassionate use included 122 patients involved in 28 different access programmes and revealed cost savings of €1,649,550. CONCLUSION: The results of our analysis point to the benefits of participating in and planning clinical trials for the public healthcare sector.

Target Therapies for Systemic Mastocytosis: An Update.

Systemic mastocytosis (SM) results from a clonal proliferation of abnormal mast cells (MCs) in extra-cutaneous organs. It could be divided into indolent SM, smoldering SM, SM with an associated hematologic (non-MC lineage) neoplasm, aggressive SM, and mast cell leukemia. SM is generally associated with the presence of a gain-of-function somatic mutation in KIT at codon 816. Clinical features could be related to MC mediator release or to uncontrolled infiltration of MCs in different organs. Whereas indolent forms have a near-normal life expectancy, advanced diseases have a poor prognosis with short survival times. Indolent forms should be considered for symptom-directed therapy, while cytoreductive therapy represents the first-line treatment for advanced diseases. Since the emergence of tyrosine kinase inhibitors (TKIs), KIT inhibition has been an attractive approach. Initial reports showed that only the rare KITD816V negative cases were responsive to first-line TKI imatinib. The development of new TKIs with activity against the KITD816V mutation, such as midostaurin or avapritinib, has changed the management of this disease. This review aims to focus on the available clinical data of therapies for SM and provide insights into possible future therapeutic targets.

Coordination complexes of niobium and tantalum pentahalides with a bulky NHC ligand.

The 1 : 1 molar reactions of niobium and tantalum pentahalides with the monodentate NHC ligand 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (Ipr), in toluene (or benzene) at ca. 80 °C, afforded the complexes NbX5(Ipr) (X = F, ; Br, ) and TaX5(Ipr) (X = F, ; Cl, ; Br, ), in generally good yields. Complexes represent uncommon cases of stable NHC adducts of metal halides with the metal in an oxidation state higher than +4, and also rare examples of Nb-NHC and Ta-NHC bonding systems. In particular, the X-ray molecular structure determined for provides the unprecedented crystallographic characterization of a tantalum compound with a monodentate NHC ligand. DFT results indicate that the metal-carbon bond in is a purely σ one. According to NMR studies ((1)H, (13)C, (93)Nb), the formation of , , , as well as the previously communicated NbCl5(Ipr), , proceeded with the intermediacy of [MX6](-) salts, presumably due to steric reasons. On the other hand, the intermediate formation of MF6(-) in the pathways to and was not observed, according to (19)F (and (93)Nb in the case of ) NMR. DFT calculations were carried out in order to shed light on structural and mechanistic aspects, and allowed to trace possible reaction routes.

A structurally-characterized NbCl5-NHC adduct.

The selective reactions of niobium pentachloride with two bulky NHC carbenes afforded NbCl5(NHC) complexes, bearing the highest oxidation state ever found for a metal centre in a transition metal halide-NHC adduct. The X-ray structure of 2a is the first one reported for a monodentate NHC-niobium species, and exhibits an abnormally long Nb-C bond.

Zoledronic acid exerts its antitumor effect in multiple myeloma interfering with the bone marrow microenvironment.

Multiple myeloma (MM) is a B-cell malignancy characterized by an excess of monotypic plasma cells which localize almost exclusively in the bone marrow provoking bone destruction via the activation of the osteoclasts. The bone marrow microenvironment, mainly through stromal cells, is strictly involved in the evolution of the disease supporting MM cell growth and survival [1]. MM plasma cells reside in the bone marrow by binding to adhesion molecule of extracellular matrix (ECM) and stromal cells. The activation of some signaling pathways within the stromal cells increases the production of several cytokines which in turn favors the myeloma cell proliferation and survival [2-6], and enhance the drug resistance by anti-apoptotic mechanisms [1,7-9]. Novel therapeutic agents target not only the myeloma cells but also the interaction between MM cells and the bone marrow microenvironment [8]. Bisphosphonates (Bps) interfere as well with bone microenvironment inhibiting the survival of stromal cells and hampering the contact between plasma and stromal cells. In this review we will revise preclinical evidences, and the potential mechanisms of the antitumor activity of zoledronic acid.

Zoledronic acid down-regulates adhesion molecules of bone marrow stromal cells in multiple myeloma: a possible mechanism for its antitumor effect.

BACKGROUND: Myeloma plasma cells interact with the bone marrow microenvironment which, in turn, supports their growth and protects them from apoptosis. In vitro studies have demonstrated the antitumor potential of zoledronic acid (ZOL) on myeloma cell lines, but few data are available on its effects on bone marrow stromal cells (BMSCs). The aim of the current study was to evaluate the antiproliferative and apoptotic effect of ZOL on BMSCs, as well as its effect on the expression of adhesion molecules. METHODS: BMSCs, obtained from bone marrow mononucleated cells of 8 patients with multiple myeloma, were treated with increasing concentrations of ZOL for 3 days. Cytotoxic effect was analyzed by 3-(4-5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide; thiazolyl blue (MTT) assay whereas the induction of apoptosis was evaluated by flow cytometric detection of fluorescein isothiocyanate-labeled annexin V, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay, and nuclear changes. Moreover, expression of CD106, CD56, CD50, CD49d, CD44, and CD40 was analyzed by flow cytometry. Data were evaluated by the Friedman test. RESULTS: After 3 days of exposure at concentrations of 10(-4) to 10(-5) M, ZOL induced a decrease in proliferation (P < 0.0001) and an increase in apoptosis (P < 0.002). Analysis of culture supernatants showed that myeloma BMSCs expressed interleukin (IL)-6, negligible levels of tumor necrosis factor-alpha, and no IL-1beta. In vitro exposure to the lowest concentrations of ZOL decreased IL-6 production by BMSCs. Among the adhesion molecules, CD106, CD54, CD49d, and CD40, which were strongly expressed at baseline, showed a statistically significant reduction compared with controls after exposure to ZOL. CONCLUSIONS: ZOL interfered with myeloma BMSCs by reducing proliferation, increasing apoptosis, and modifying the pattern of expression of adhesion molecules, especially those involved in plasma cell binding. These effects on BMSCs might explain the antitumor activity of ZOL.