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Hypophosphatasia (HPP) is a rare, inherited metabolic disease caused by deficient activity of tissue-nonspecific alkaline phosphatase (TNSALP). Efzimfotase alfa (ALXN1850) is a second-generation TNSALP enzyme replacement therapy in development for HPP. This first-in-human open-label, dose-escalating phase 1 trial evaluated efzimfotase alfa safety, tolerability, pharmacokinetics, pharmacodynamics, and immunogenicity. Fifteen adults (5/cohort) with HPP received efzimfotase alfa in doses of 15 mg (cohort 1), 45 mg (cohort 2), or 90 mg (cohort 3) as one intravenous (i.v.) dose followed by 3 weekly subcutaneous (s.c.) doses. The primary objective was to assess safety and tolerability. Secondary objectives included pharmacokinetics, pharmacodynamics of ALP substrates known to be biomarkers of disease (inorganic pyrophosphate [PPi] and pyridoxal 5′-phosphate [PLP]) and immunogenicity. Treatment-emergent adverse events (TEAEs) occurred in 12 (80%) participants. Eight (53%) participants had injection site reactions (ISRs), observed after 10 of 41 (24%) s.c. injections. Most ISR TEAEs were mild and resolved within 1–2 d. Peak and total exposures of efzimfotase alfa increased in a greater-than-dose proportional manner over the range of 15–90 mg after i.v. and s.c. dosing. The arithmetic mean elimination half-life was approximately 6 d; absolute bioavailability was 28.6%–36.8% over the s.c. dose range of 15–90 mg. Dose-dependent reductions in plasma concentrations of PPi and PLP relative to baseline reached nadir in the first week after i.v. dosing and were sustained for 3–4 wk after the last s.c. dose. Four (27%) participants tested positive for antidrug antibodies (ADAs), 3 of whom were ADA positive before the first dose of efzimfotase alfa. ADAs had no apparent effect on efzimfotase alfa pharmacokinetics/pharmacodynamics. No participants had neutralizing antibodies. Efzimfotase alfa demonstrated acceptable safety, tolerability, and pharmacokinetic profiles and was associated with sustained reductions in biomarkers of disease in adults with HPP, supporting further evaluation in adult and pediatric patients. Registration: ClinicalTrials.gov NCT04980248 (https://clinicaltrials.gov/study/NCT04980248). Lay Summary: Hypophosphatasia (HPP) is a rare metabolic disease caused by low activity of tissue nonspecific alkaline phosphatase (TNSALP), which is an enzyme involved in the formation and healing of bone and function of other body systems. People with HPP experience fractures, difficulty moving and walking, muscle weakness, pain, fatigue (tiredness), and teeth problems. Babies with HPP often have life-threatening breathing problems, craniosynostosis (early closure of skull bones), seizures that respond to treatment with vitamin B6, failure to thrive (inability to gain weight), and weak and abnormally shaped bones. Enzyme replacement therapy (ERT) for HPP was developed to supplement defective TNSALP with active enzyme, thus improving bone health and the symptoms of HPP. Asfotase alfa, the first ERT approved for the treatment of HPP, is given by subcutaneous injection either 3 or 6 times per week. Efzimfotase alfa is a second-generation ERT that is being developed for the treatment of HPP. Although similar to asfotase alfa, efzimfotase alfa has incorporated several changes that have the potential to require lower doses and reduce injection volume and dosing frequency, thereby potentially improving the treatment experience for patients. This first-in-human study investigated the safety, tolerability, pharmacokinetics (how a drug is absorbed into, distributed throughout, and removed from the body), pharmacodynamics (effects of the drug within the body), and immunogenicity (ability of a drug to provoke an undesirable immune response) of 4 injections of efzimfotase alfa when given by intravenous and subcutaneous routes of administration to adults with HPP. Our results showed that efzimfotase alfa has acceptable safety and pharmacokinetics and is effective for reducing biomarkers (measurable substances that reflect underlying disease) when given once weekly by subcutaneous injection, supporting further evaluation of efzimfotase alfa in planned clinical trials in adult and pediatric patients with HPP. [ABSTRACT FROM AUTHOR]

Molecular modeling was employed to explore the mechanism underlying the [alpha]-hydroxy group interaction with the class C [beta]-lactamase active site. The [alpha]-hydroxyalkyl moiety with ability to spontaneously decarboxylate in aqueous neutral buffer to form O-(2-hydroxyalkylcarbonyl) hydroxamates might find potential application when incorporated with novel inhibitors.

A series of new inhibitors is prepared to examine the kinetics and mechanisms of the inactivation reaction of serine [beta]-lactamase by O-aryloxycarbonyl hydroxamates. The studies have shown that the new series of analogues have reacted differently with the active site of a class C [beta]-lactamase than do normal substrates.

The study described various O-aryloxycarbonyl hydroxamates, which are used as the new [beta]-lactamase inhibitors that also lead to cross-linking of active site residues.