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The nuclear protein poly(ADP-ribose) polymerase-1 (PARP-1) has a well-established role in the signaling and repair of DNA and is a prominent target in oncology, as testified by the number of candidates in clinical testing that unselectively target both PARP-1 and its closest isoform PARP-2. The goal of our program was to find a PARP-1 selective inhibitor that would potentially mitigate toxicities arising from cross-inhibition of PARP-2. Thus, an HTS campaign on the proprietary Nerviano Medical Sciences (NMS) chemical collection, followed by SAR optimization, allowed us to discover 2-[1-(4,4-difluorocyclohexyl)piperidin-4-yl]-6-fluoro-3-oxo-2,3-dihydro-1H-isoindole-4-carboxamide (NMS-P118, 20by). NMS-P118 proved to be a potent, orally available, and highly selective PARP-1 inhibitor endowed with excellent ADME and pharmacokinetic profiles and high efficacy in vivo both as a single agent and in combination with Temozolomide in MDA-MB-436 and Capan-1 xenograft models, respectively. Cocrystal structures of 20by with both PARP-1 and PARP-2 catalytic domain proteins allowed rationalization of the observed selectivity.

Introduction: Choline kinase alpha (ChoKα), the first enzyme in the Kennedy pathway that catalyzes the phosphorylation of free choline to phosphocholine (PCho), is responsible for the de novo biosynthesis of phosphatidylcholine (PC), the major phospholipid of cellular membranes. Aberrant choline metabolic profiles and concomitant ChoKα upregulation have been described in most human malignancies (i.e. breast, lung, ovary, liver) and have been found to correlate with advanced histological tumour grade. ChoKα, depletion by siRNA or shRNA inhibits growth and migration of different tumor cell lines both in vitro and in vivo, which is not observed for the ChoKβ isoform. Choline mimetic inhibitors of ChoKα (i.e. MN58b) have been shown to have antitumor activity in preclinical models, although their efficacy is hampered by a significant toxicity, possibly due to cross-reactivity with other choline-dependent proteins (transporters, enzymes). At NMS a high throughput screening (HTS) was performed with the objective to identify ATP-mimetic ChoKα inhibitors potentially less toxic than choline-mimetic compounds. Methods: Hits from different classes were characterized for biochemical activity on ChoKα and ChoKβ and biochemical mechanism of inhibition. The binding site of selected ATP competitive inhibitors was confirmed by co-crystallization with ChoKα. On-target mechanism of action in cells was confirmed by analysing inhibition of PCho formation. Result: Structure-based chemical expansion of Hits from one of the prioritized classes resulted in compounds with biochemical potencies in the single digit nanomolar range displaying selectivity vs ChoKβ as well as a diverse panel of protein kinases. In several tumor cell lines, the compounds were able to inhibit the formation of PCho at a concentration in agreement with that required to achieve anti-proliferative activity. The most potent compounds were tested on a panel of 24 representative breast cancer cell lines which showed differential sensitivity towards ChoKα inhibition. Analysis of genomic (DNA and RNA) and proteomic (>50 markers) expression profiles of the breast cancer cell lines is ongoing to identify predictive biomarkers of response. Conclusion: Medicinal chemistry expansion of a novel class of compounds identified by HTS allowed the development of potent ChoKα ATP-mimetic inhibitors able to modulate PCho levels in cells, which can be used to identify preferential sensitivity contexts. Medicinal chemistry activities are ongoing to further improve their potency and optimize their ADME/PK properties. Citation Format: Paola Gnocchi, Francesca Quartieri, Alessandra Badari, Roberta Bosotti, Elena Casale, Emiliana Corti, Cinzia G. Cristiani, Ulisse Cucchi, Fabio Gasparri, Laura M. Gianellini, Laura M. Giorgini, Marisa Montemartini, Giuliana Mion, Marcella Nesi, Christian Orrenius, Claudia E. Re, Daniele Donati, Eduard R. Felder, Arturo Galvani, Antonella Isacchi. Identification and characterization of ATP-mimetic choline kinase inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4790.

Summary Antibiotics blocking bacterial cell wall assembly (β-lactams and glycopeptides) are facing a challenge from the progressive spread of resistant pathogens. Lantibiotics are promising candidates to alleviate this problem. Microbisporicin, the most potent antibacterial among known comparable lantibiotics, was discovered during a screening applied to uncommon actinomycetes. It is produced by Microbispora sp. as two similarly active and structurally related polypeptides (A1, 2246-Da and A2, 2230-Da) of 24 amino acids linked by 5 intramolecular thioether bridges. Microbisporicin contains two posttranslational modifications that have never been reported previously in lantibiotics: 5-chloro-trypthopan and mono- (in A2) or bis-hydroxylated (in A1) proline. Consistent with screening criteria, microbisporicin selectively blocks peptidoglycan biosynthesis, causing cytoplasmic UDP-linked precursor accumulation. Considering its spectrum of activity and its efficacy in vivo, microbisporicin represents a promising antibiotic to treat emerging infections.

GE 23077 factors A1, A2, B1 and B2 are novel antibiotics isolated from fermentation broths of an Actinomadura sp. strain. GE23077 antibiotics are cyclic peptides, which inhibit Escherichia coli RNA polymerase at nM concentrations. Both rifampicin-sensitive and rifampicin-resistant polymerases are inhibited, whereas E. coli DNA polymerase and wheat germ RNA polymerase are substantially not affected. In spite of the potent activity on the enzyme, the antibiotics generally show poor activity against whole cell bacteria. The spectrum of activity is restricted to Moraxella catarrhalis, including clinical isolates, with partial activity against Neisseria gonorrhoeae and Mycobacterium smegmatis.

Cancer cell survival is frequently dependent on the elevated levels of members of the Bcl-2 family of prosurvival proteins that bind to and inactivate BH3-domain pro-apoptotic cellular proteins. Small molecules that inhibit the protein–protein interactions between prosurvival and proapoptotic Bcl-2 family members (so-called “BH3 mimetics”) have a potential therapeutic value, as indicated by clinical findings obtained with ABT-263 (navitoclax), a Bcl-2/Bcl-xL antagonist, and more recently with GDC-0199/ABT-199, a more selective antagonist of Bcl-2. Here, we report study results of the functional role of the prosurvival protein Mcl-1 against a panel of solid cancer cell lines representative of different tumor types. We observed silencing of Mcl-1 expression by small interfering RNAs (siRNAs) significantly reduced viability and induced apoptosis in almost 30% of cell lines tested, including lung and breast adenocarcinoma, as well as glioblastoma derived lines. Most importantly, we provide a mechanistic basis for this sensitivity by showing antagonism of Mcl-1 function with specific BH3 peptides against isolated mitochondria induces Bak oligomerization and cytochrome c release, therefore demonstrating that mitochondria from Mcl-1-sensitive cells depend on Mcl-1 for their integrity and that antagonizing Mcl-1 function is sufficient to induce apoptosis. Thus, our results lend further support for considering Mcl-1 as a therapeutic target in a number of solid cancers and support the rationale for development of small molecule BH3-mimetics antagonists of this protein.

We examined the clinical effect of sulbactam/cefoperazone (SBT/CPZ) on respiratory tract infections in elderly patients (from 65 to 91, average 70.8) with underlying respiratory diseases. Thirty (30) patients (25 men and 5 women) were registered and SBT/CPZ (2 g/day) divided into two doses, was administered intravenously through drip infusion. The efficacy rate was 63% (excellent in 1 patient and good in 18 patients). No significant difference in efficacy was found among patient's age groups (group 1: 65-69, group 2: 70-74, group 3: 75-79, group 4: > 80). Bacterial eradication rate was 50% (6 out of 12 strains). An adverse reaction occurred in one patient, who experienced uticaria. Laboratory abnormalities, which were increasing with their ages, were observed in 12 patients during the study. These results suggest that SBT/CPZ was effective, but we found it is important to use caution in the treatment of elderly patients on respiratory tract infections with underlying respiratory diseases.