Characterization of Pharmacokinetics, Biotransformation and Elimination of Pomotrelvir Orally Administered in Healthy Male Adults Using Two [14C]-Labeled Microtracers with Separate Labeling Positions.

Pomotrelvir is an orally bioavailable, target antiviral inhibitor of the main protease (Mpro) of coronaviruses, including severe acute respiratory syndrome coronavirus 2, the etiological agent of Coronavirus Disease 2019. The pharmacokinetics, metabolism and elimination of two [14C]-labeled microtracers of 5 µCi/700 mg pomotrelvir with separate labeling positions (isotopomers), [lactam carbonyl-14C-pomotelvir] and [benzene ring-U-14C-pomotrelvir], following a single oral dose in healthy adult males was evaluated in two separate cohorts. Pomotrelvir was rapidly absorbed and eliminated primarily through metabolism and subsequently excreted via urine and feces. There were no differences in pomotrelvir pharmacokinetics between the two cohorts. The mean total radioactive dose recovered was 93.8% (n = 8) in the lactam cohort (58% in urine and 36% in feces) and 94.2% (n = 8) in the benzene cohort (75% in urine and 19% in feces), with ≥80% of [14C] recovered within 96 hours after dosing. About 5% and 3% of the intact pomotrelvir was recovered in feces and urine, respectively. Eleven major metabolites were detected and characterized using liquid chromatography-accelerator mass spectrometry and liquid chromatography tandem mass spectrometry methods, with three and six different metabolites elucidated in the samples collected from lactam and benzene cohorts, respectively, and two metabolites observed in both cohorts. The major metabolism pathway of pomotrelvir is through hydrolysis of its peptide bonds followed by phase II conjugations. These results support that the application of two radiolabeled isotopomers provided a comprehensive metabolite profiling analysis and was a successful approach in identifying the major disposition pathways of pomotrelvir that has complex routes of metabolism. SIGNIFICANCE STATEMENT: An unconventional approach using two differentially labeled [14C] microtracers, [lactam carbonyl-14C-pomotrelvir] and [benzene ring-U-14C-pomotrelvir] evaluated the mass balance of orally administered pomotrelvir in healthy adult males in two separate cohorts. The radioactive dose recovered in excreta was about 94% for both cohorts. While the two isotopomers of the radiolabeled-pomotrelvir showed no major differences in pharmacokinetics overall, they allowed for differential detection of their radiolabeled metabolites and appropriate characterization of their plasma exposure and excretion in urine and feces.

Design of BET Inhibitor Bottlebrush Prodrugs with Superior Efficacy and Devoid of Systemic Toxicities.

Prodrugs engineered for preferential activation in diseased versus normal tissues offer immense potential to improve the therapeutic indexes (TIs) of preclinical and clinical-stage active pharmaceutical ingredients that either cannot be developed otherwise or whose efficacy or tolerability it is highly desirable to improve. Such approaches, however, often suffer from trial-and-error design, precluding predictive synthesis and optimization. Here, using bromodomain and extra-terminal (BET) protein inhibitors (BETi)-a class of epigenetic regulators with proven anticancer potential but clinical development hindered in large part by narrow TIs-we introduce a macromolecular prodrug platform that overcomes these challenges. Through tuning of traceless linkers appended to a "bottlebrush prodrug" scaffold, we demonstrate correlation of in vitro prodrug activation kinetics with in vivo tumor pharmacokinetics, enabling the predictive design of novel BETi prodrugs with enhanced antitumor efficacies and devoid of dose-limiting toxicities in a syngeneic triple-negative breast cancer murine model. This work may have immediate clinical implications, introducing a platform for predictive prodrug design and potentially overcoming hurdles in drug development.

Pharmacological Characterization of SDX-7320/Evexomostat: A Novel Methionine Aminopeptidase Type 2 Inhibitor with Anti-tumor and Anti-metastatic Activity.

Methionine aminopeptidase type 2 (METAP2) is a ubiquitous, evolutionarily conserved metalloprotease fundamental to protein biosynthesis which catalyzes removal of the N-terminal methionine residue from nascent polypeptides. METAP2 is an attractive target for cancer therapeutics based upon its over-expression in multiple human cancers, the importance of METAP2-specific substrates whose biological activity may be altered following METAP2 inhibition, and additionally, that METAP2 was identified as the target for the anti-angiogenic natural product, fumagillin. Irreversible inhibition of METAP2 using fumagillin analogues has established the anti-angiogenic and anti-tumor characteristics of these derivatives; however, their full clinical potential has not been realized due to a combination of poor drug-like properties and dose-limiting central nervous system (CNS) toxicity. This report describes the physicochemical and pharmacological characterization of SDX-7320 (evexomostat), a polymer-drug conjugate of the novel METAP2 inhibitor (METAP2i) SDX-7539. In vitro binding, enzyme, and cell-based assays demonstrated that SDX-7539 is a potent and selective METAP2 inhibitor. In utilizing a high molecular weight, water-soluble polymer to conjugate the novel fumagillol-derived, cathepsin-released, METAP2i SDX-7539, limitations observed with prior generation, small molecule fumagillol derivatives were ameliorated including reduced CNS exposure of the METAP2i, and prolonged half-life enabling convenient administration. Multiple xenograft and syngeneic cancer models were utilized to demonstrate the anti-tumor and anti-metastatic profile of SDX-7320. Unlike polymer-drug conjugates in general, reductions in small molecule-equivalent efficacious doses following polymer conjugation were observed. SDX-7320 has completed a phase I clinical safety study in patients with late-stage cancer and is currently being evaluated in multiple phase Ib/II clinical studies in patients with advanced solid tumors.

Pharmacodynamic Activity of the Novel Neurokinin-3 Receptor Antagonist SJX-653 in Healthy Men.

CONTEXT: SJX-653 is a novel neurokinin 3 receptor (NK3R) antagonist. The NK3 pathway is a central regulator of gonadotropin releasing hormone (GnRH) secretion and has also been implicated in the generation of hot flashes. Therefore, decreases of luteinizing hormone (LH) and testosterone in men serve as sensitive pharmacodynamic (PD) markers of central NK3 antagonism. OBJECTIVE: To characterize the safety, tolerability, pharmacokinetics, and pharmacodynamic activity of SJX-653 in healthy men. DESIGN: A randomized, placebo-controlled, double-blind, single ascending dose study. SETTING: Phase 1 unit. PATIENTS OR OTHER PARTICIPANTS: Seven cohorts of 6 healthy men 18-45 years of age (4:2 randomization to SJX-653/placebo per cohort). INTERVENTION(S): Single oral doses of 0.5-90 mg SJX-653. MAIN OUTCOME MEASURE(S): Safety assessments and serial pharmacokinetic (PK)/PD measurements. RESULTS: SJX-653 was well tolerated at all dose levels. Cmax and AUC0-24 increased in a dose-proportional manner. The terminal elimination half-life ranged between 9.8 and 12.5 hours independent of dose. A statistically significant, dose-dependent, reversible reduction of LH and testosterone was observed with near maximal effect after 15 mg and little to no effect at 4.5 mg. Maximal LH reduction was 70 ±â€…7% (mean ±â€…sd) at 6 hours after 30 mg SJX-653 versus 10 ±â€…43% for placebo (P = 0.0006); maximal T reduction was of 68 ±â€…5% at 8 hours after 60 mg SJX-653 versus 18 ±â€…11% for placebo (P < 0.0001). The plasma IC50 for LH reduction was 33 ng/mL. CONCLUSIONS: These data demonstrate clinical proof-of-mechanism for SJX-653 as a potent centrally-acting NK3R antagonist.

A Randomized Phase I Evaluation of CTP-499, a Novel Deuterium-Containing Drug Candidate for Diabetic Nephropathy.

To determine maximum tolerated dose and food effect for CTP-499, a novel agent being studied for the treatment of diabetic kidney disease. CTP-499 has demonstrated anti-inflammatory, anti-fibrotic and anti-oxidative activities in vitro as well as anti-inflammatory and renoprotective effects in a diabetic nephropathy (DN) model. Two studies were performed. Study 1 was a single-dose escalation study with 600, 1200, 1800, and 2400 mg doses of controlled-release (CR) CTP-499 and a 400 mg immediate release dose to aid in the development of prototype formulations of CTP-499. Study 2 was a food-effect study. Plasma concentrations of CTP-499 and its metabolites were measured to determine pharmacokinetic parameters in each study. Safety was assessed to determine tolerability. Doses up to and including 1800 mg were well tolerated. Cmax was either equivalent (CTP-499) or slightly lower (metabolites) for the fed condition, while overall exposure was equivalent (CTP-499) or slightly higher (metabolites) for the fed condition. The range of tolerated doses of CTP-499 and the effects of food on exposure were identified, contributing to selection of the dose for Phase II development.

Vision correction with excimer lasers.

Excimer lasers were invented in 1975, and the first human eye treatment with VISX laser technology was in 1987. Since then many advances in LASIK surgery and related diagnostic and control techniques have led to improved vision correction with over 95% of patients corrected to 20/20 vision or better. This paper describes the development of excimer laser surgery and recent results, wavefront-guided vision correction methods, and the equipment required to achieve these results. Specific requirements imposed on the 193 nm excimer laser, on the laser beam control, the electronic controls, and the controlling software have led to development of laser systems and diagnostic systems unique to LASIK surgery. These include development of a highly reliable laser system with tightly controlled energy output and precision beam shaping and positioning. This development and widely successful use in refractive surgery are reviewed in this paper.