Discovery of Stereospecific PARP-1 Inhibitor Isoindolinone NMS-P515.

Poly(ADP-ribose) polymerase-1 (PARP-1) is an enzyme involved in signaling and repair of DNA single strand breaks. PARP-1 employs NAD+ to modify substrate proteins via the attachment of poly(ADP-ribose) chains. PARP-1 is a well established target in oncology, as testified by the number of marketed drugs (e.g., Lynparza, Rubraca, Zejula, and Talzenna) used for the treatment of ovarian, breast, and prostate tumors. Efforts in investigating an uncharted region of the previously identified isoindolinone carboxamide series delivered (S)-13 (NMS-P515), a potent inhibitor of PARP-1 both in biochemical (K d: 0.016 µM) and cellular (IC50: 0.027 µM) assays. Cocrystal structure allowed explaining NMS-P515 stereospecific inhibition of the target. After having ruled out potential loss of enantiopurity in vitro and in vivo, NMS-P515 was synthesized in an asymmetric fashion. NMS-P515 ADME profile and its antitumor activity in a mouse xenograft cancer model render the compound eligible for further optimization.

Discovery of NMS-E973 as novel, selective and potent inhibitor of heat shock protein 90 (Hsp90).

Novel small molecule inhibitors of heat shock protein 90 (Hsp90) were discovered with the help of a fragment based drug discovery approach (FBDD) and subsequent optimization with a combination of structure guided design, parallel synthesis and application of medicinal chemistry principles. These efforts led to the identification of compound 18 (NMS-E973), which displayed significant efficacy in a human ovarian A2780 xenograft tumor model, with a mechanism of action confirmed in vivo by typical modulation of known Hsp90 client proteins, and with a favorable pharmacokinetic and safety profile.

NMS-E973, a novel synthetic inhibitor of Hsp90 with activity against multiple models of drug resistance to targeted agents, including intracranial metastases.

PURPOSE: Recent developments of second generation Hsp90 inhibitors suggested a potential for development of this class of molecules also in tumors that have become resistant to molecular targeted agents. Disease progression is often due to brain metastases, sometimes related to insufficient drug concentrations within the brain. Our objective was to identify and characterize a novel inhibitor of Hsp90 able to cross the blood-brain barrier (BBB). EXPERIMENTAL DESIGN: Here is described a detailed biochemical and crystallographic characterization of NMS-E973. Mechanism-based anticancer activity was described in cell models, including models of resistance to kinase inhibitors. Pharmacokinetics properties were followed in plasma, tumor, liver, and brain. In vivo activity and pharmacodynamics, as well as the pharmacokinetic/pharmacodynamic relationships, were evaluated in xenografts, including an intracranially implanted melanoma model. RESULTS: NMS-E973, representative of a novel isoxazole-derived class of Hsp90 inhibitors, binds Hsp90α with subnanomolar affinity and high selectivity towards kinases, as well as other ATPases. It possesses potent antiproliferative activity against tumor cell lines and a favorable pharmacokinetic profile, with selective retention in tumor tissue and ability to cross the BBB. NMS-E973 induces tumor shrinkage in different human tumor xenografts, and is highly active in models of resistance to kinase inhibitors. Moreover, consistent with its brain penetration, NMS-E973 is active also in an intracranially implanted melanoma model. CONCLUSIONS: Overall, the efficacy profile of NMS-E973 suggests a potential for development in different clinical settings, including tumors that have become resistant to molecular targeted agents, particularly in cases of tumors which reside beyond the BBB.

Synthesis and SAR of new pyrazolo[4,3-h]quinazoline-3-carboxamide derivatives as potent and selective MPS1 kinase inhibitors.

The synthesis and SAR of a series of novel pyrazolo-quinazolines as potent and selective MPS1 inhibitors are reported. We describe the optimization of the initial hit, identified by screening the internal library collection, into an orally available, potent and selective MPS1 inhibitor.

Pharmacokinetics and excretion of dalbavancin in the rat.

OBJECTIVES: The pharmacokinetics, tissue distribution and excretion routes of dalbavancin, a semi-synthetic glycopeptide, were investigated in rats. METHODS: A 20 mg/kg intravenous dose of dalbavancin or [(3)H]dalbavancin was administered to rats in three studies. Concentrations of dalbavancin or drug-derived radioactivity were assessed in blood, plasma, tissues, bile, urine and faeces by HPLC-MS/MS, scintillation counting or microbiological methods. RESULTS: Dalbavancin decayed tri-exponentially in plasma with an apparent terminal t(1/2) of 187 h (approximately 8 days). Dalbavancin has dual routes of elimination, with around two-thirds of the excreted drug-derived radioactivity being found in the urine and around one-third in the faeces. After 70 days, 44.2% and 22.3% of the drug-derived radioactivity had been recovered in the urine and faeces, respectively. Biliary excretion of drug-derived radioactivity accounted for over half of the radioactivity excreted faecally. At 70 days post-dose, <5% of the dose remained in the carcass, showing that drug elimination was complete. CONCLUSIONS: Dalbavancin has a long t(1/2) (approximately 8 days) in the rat and distributes widely throughout the body. It is not selectively retained in any single organ, tissue or blood component and is completely eliminated by both renal and non-renal routes in rats. These data were useful in designing and interpreting animal infection model studies used to select the dose for human studies.