Comparison of autoinjector with accessorized prefilled syringe for benralizumab pharmacokinetic exposure: AMES trial results.

OBJECTIVE: We compared the pharmacokinetic exposure following a single subcutaneous dose of benralizumab 30 mg using either autoinjectors (AI) or accessorized prefilled syringes (APFS). APFS and AI functionality and reliability for at-home benralizumab delivery have been demonstrated in the GREGALE and GRECO studies, respectively. METHODS: In the open-label AMES study (NCT02968914), 180 healthy adult men and women were randomized to one of two device (AI or APFS) and three injection site (upper arm, abdomen, or thigh) combinations. Randomization was stratified by weight (<70 kg, 70-84.9 kg, and ≥85 kg). Blood eosinophil counts were measured on Days 1, 8, 29, and 57. RESULTS: Benralizumab pharmacokinetic exposure was similar between AI and APFS. Geometric mean ratios (AI/APFS) (90% CI) were 92.8% (87.4-98.6) and 94.5% (88.2-101.2) for two area under the concentration‒time curve measurements (AUClast and AUCinf). Benralizumab exposure was approximately 15-30% greater for thigh vs. abdomen or upper arm administration. Exposure was slightly greater for APFS vs. AI regardless of injection site or weight class. These differences were unlikely to be clinically relevant, as eosinophil depletion was achieved consistently with both devices at all injection sites. No device malfunctions were reported. No new or unexpected safety findings were observed. CONCLUSION: Benralizumab pharmacokinetic exposure was similar between AI and APFS, with consistent blood eosinophil count depletion observed with both devices. These results support benralizumab administration with either AI or APFS, providing patients and physicians increased choice, flexibility, and convenience for potential at-home delivery.

LCAT Enzyme Replacement Therapy Reduces LpX and Improves Kidney Function in a Mouse Model of Familial LCAT Deficiency.

Familial LCAT deficiency (FLD) is due to mutations in lecithin:cholesterol acyltransferase (LCAT), a plasma enzyme that esterifies cholesterol on lipoproteins. FLD is associated with markedly reduced levels of plasma high-density lipoprotein and cholesteryl ester and the formation of a nephrotoxic lipoprotein called LpX. We used a mouse model in which the LCAT gene is deleted and a truncated version of the SREBP1a gene is expressed in the liver under the control of a protein-rich/carbohydrate-low (PRCL) diet-regulated PEPCK promoter. This mouse was found to form abundant amounts of LpX in the plasma and was used to determine whether treatment with recombinant human LCAT (rhLCAT) could prevent LpX formation and renal injury. After 9 days on the PRCL diet, plasma total and free cholesterol, as well as phospholipids, increased 6.1 ± 0.6-, 9.6 ± 0.9-, and 6.7 ± 0.7-fold, respectively, and liver cholesterol and triglyceride concentrations increased 1.7 ± 0.4- and 2.8 ±0.9-fold, respectively, compared with chow-fed animals. Transmission electron microscopy revealed robust accumulation of lipid droplets in hepatocytes and the appearance of multilamellar LpX particles in liver sinusoids and bile canaliculi. In the kidney, LpX was found in glomerular endothelial cells, podocytes, the glomerular basement membrane, and the mesangium. The urine albumin/creatinine ratio increased 30-fold on the PRCL diet compared with chow-fed controls. Treatment of these mice with intravenous rhLCAT restored the normal lipoprotein profile, eliminated LpX in plasma and kidneys, and markedly decreased proteinuria. The combined results suggest that rhLCAT infusion could be an effective therapy for the prevention of renal disease in patients with FLD.

A retractable lid in lecithin:cholesterol acyltransferase provides a structural mechanism for activation by apolipoprotein A-I.

Lecithin:cholesterol acyltransferase (LCAT) plays a key role in reverse cholesterol transport by transferring an acyl group from phosphatidylcholine to cholesterol, promoting the maturation of high-density lipoproteins (HDL) from discoidal to spherical particles. LCAT is activated through an unknown mechanism by apolipoprotein A-I (apoA-I) and other mimetic peptides that form a belt around HDL. Here, we report the crystal structure of LCAT with an extended lid that blocks access to the active site, consistent with an inactive conformation. Residues Thr-123 and Phe-382 in the catalytic domain form a latch-like interaction with hydrophobic residues in the lid. Because these residues are mutated in genetic disease, lid displacement was hypothesized to be an important feature of apoA-I activation. Functional studies of site-directed mutants revealed that loss of latch interactions or the entire lid enhanced activity against soluble ester substrates, and hydrogen-deuterium exchange (HDX) mass spectrometry revealed that the LCAT lid is extremely dynamic in solution. Upon addition of a covalent inhibitor that mimics one of the reaction intermediates, there is an overall decrease in HDX in the lid and adjacent regions of the protein, consistent with ordering. These data suggest a model wherein the active site of LCAT is shielded from soluble substrates by a dynamic lid until it interacts with HDL to allow transesterification to proceed.