In Vivo Activity of the Pyrrolopyrazolyl-Substituted Oxazolidinone RWJ-416457▿

RWJ-416457 is an investigational pyrrolopyrazolyl-substituted oxazolidinone with activity against antibiotic-susceptible and -resistant gram-positive pathogens. Efficacies of RWJ-416457, linezolid, and vancomycin against methicillin-susceptible Staphylococcus aureus (MSSA) and community-associated methicillin-resistant S. aureus (CA-MRSA) in murine skin and systemic infections were compared, as were efficacies against Streptococcus pneumoniae in a lower respiratory infection. In staphylococcal systemic infections, RWJ-416457 was equipotent with to twofold more potent than linezolid, with 50% effective dose values ranging from 1.5 to 5 mg/kg of body weight/day. RWJ-416457 was two- to fourfold less potent than vancomycin against MSSA but up to fourfold more potent than vancomycin against CA-MRSA. In MSSA and CA-MRSA skin infections, RWJ-416457 demonstrated an efficacy similar to that of linezolid, reducing CFU/g skin approximately 1.0 log10 at all doses tested; vancomycin yielded greater reductions than the oxazolidinones, with decreases in CFU/g skin of 3 log10 (MSSA) and 2 log10 (CA-MRSA). In the pneumococcal model, RWJ-416457 was two- to fourfold more potent than linezolid. The free-drug area under the concentration-time curves at 24 h (fAUC24) were similar for RWJ-416457 and linezolid. The half-life of RWJ-416457 was up to threefold longer than that of linezolid for all routes of administration. The fAUC24/MIC ratio, the pharmacodynamic parameter considered predictive of oxazolidinone efficacy, was approximately twofold greater for RWJ-416457 than for linezolid. Since the fAUC values were similar for both compounds, the higher fAUC/MIC ratios of RWJ-416457 appear to result from its greater in vitro potency. These results demonstrate that RWJ-416457 is a promising new oxazolidinone with efficacy in S. aureus or S. pneumoniae mouse infection models

In Vitro Antibacterial Activities of JNJ-Q2, a New Broad-Spectrum Fluoroquinolone ▿ ‡

JNJ-Q2, a novel fluorinated 4-quinolone, was evaluated for its antibacterial potency by broth and agar microdilution MIC methods in studies focused on skin and respiratory tract pathogens, including strains exhibiting contemporary fluoroquinolone resistance phenotypes. Against a set of 118 recent clinical isolates of Streptococcus pneumoniae, including fluoroquinolone-resistant variants bearing multiple DNA topoisomerase target mutations, an MIC90 value for JNJ-Q2 of 0.12 μg/ml was determined, indicating that it was 32-fold more potent than moxifloxacin. Against a collection of 345 recently collected methicillin-resistant Staphylococcus aureus (MRSA) isolates, including 256 ciprofloxacin-resistant strains, the JNJ-Q2 MIC90 value was 0.25 μg/ml, similarly indicating that it was 32-fold more potent than moxifloxacin. The activities of JNJ-Q2 against Gram-negative pathogens were generally comparable to those of moxifloxacin. In further studies, JNJ-Q2 exhibited bactericidal activities at 2× and 4× MIC levels against clinical isolates of S. pneumoniae and MRSA with various fluoroquinolone susceptibilities, and its activities were enhanced over those of moxifloxacin. In these studies, the activity exhibited against strains bearing gyrA, parC, or gyrA plus parC mutations was indicative of the relatively balanced (equipotent) activity of JNJ-Q2 against the DNA topoisomerase target enzymes. Finally, determination of the relative rates or frequencies of the spontaneous development of resistance to JNJ-Q2 at 2× and 4× MICs in S. pneumoniae, MRSA, and Escherichia coli were indicative of a lower potential for resistance development than that for current fluoroquinolones. In conclusion, JNJ-Q2 exhibits a range of antibacterial activities in vitro that is supportive of its further evaluation as a potential new agent for the treatment of skin and respiratory tract infections

In Vitro Antibacterial Activity of the Pyrrolopyrazolyl-Substituted Oxazolidinone RWJ-416457

RWJ-416457, an investigational pyrrolopyrazolyl-substituted oxazolidinone, inhibited the growth of linezolid-susceptible staphylococci, enterococci, and streptococci at concentrations of ≤4 μg/ml, generally exhibiting two- to fourfold-greater potency than that of linezolid. Time-kill studies demonstrated bacteriostatic effects for both RWJ-416457 and linezolid

A Role for Schwann Cells in the Neuroregenerative Effects of a Non-Immunosuppressive FK506 Derivative, JNJ460

FK506 and its non-immunosuppressive derivatives represent a class of pharmacological agents referred to as immunophilin ligands that have been reported to promote neuroregeneration and survival in several experimental models; however their cellular and molecular mechanisms of action have not been well established. Here we characterize a new immunophilin ligand that interacts with both FK506 binding protein 12 (FKBP12) and FKBP52, and demonstrate that JNJ460 induces neurite outgrowth from freshly explanted dorsal root ganglia (DRG) in a Schwann cell-dependent manner. Purified cultures of neurons fail to respond to these drugs, but cultures containing Schwann cells and neurons respond with neurite outgrowth, as do neurons grown in conditioned medium from JNJ460-treated Schwann cells. Using microarray analysis and a transcription reporter assay, we show that JNJ460 induces a series of transcriptional changes that occur in a temporal cascade. Among the Schwann cell-expressed genes upregulated following JNJ460 treatment is the POU transcription factor SCIP, which has been shown to regulate Schwann cell gene transcription and differentiation. JNJ460 potentiated transforming growth factor β (TGF-β)-induced transcriptional activation and SCIP induction in Schwann cells, by altering the interaction between FKBP12 and the TGF-β type I receptor, TβR1. Finally, to test whether JNJ460 enhances neurite regeneration in vivo, we treated animals with JNJ460 for 30 days following mechanical transection of the sciatic nerve and demonstrated myelin and axonal hypertrophy at the ultrastructural level. Collectively, these data suggest that Schwann cells play an important role in the biological effects of immunophilin ligands by affecting neuron-glial signaling during regeneration. Summary: The cellular and molecular mechanisms responsible for the regenerative effects of immunophilin ligands are not well understood. Here we show that the neuritogenic effects of JNJ460 in a DRG model depend on interactions between neurons and Schwann cells. Treatment of purified Schwann cells with JNJ460 alters Schwann cell gene expression, and promotes the generation of factors that act on neurons. These data indicate that Schwann cells play an important role in the actions of immunophilin ligands

Crystallization of a Cephalosporin and an ERR-1: Assembly of an Inexpensive Crystallization Platform

Finding a stable crystalline form of a small molecule API can be a daunting task given short timelines and the importance of having a crystal form in the development of the molecule. Crystalline forms of small molecules are sought for various reasons, such as purity, chemical, and/or physical stability. In this report, we will highlight the design and process that was utilized to develop an inexpensive and simple screening platform. Our goal was to utilize existing equipment and to develop a straightforward workflow that would enable us to quickly define a set of scalable crystallization conditions and prepare a sample of the target cephalosporin and ERR-1 for preclinical testing