ABSTRACT
This 78-week (18-month) study conducted in 479 postmenopausal women with osteoporosis evaluated the efficacy, pharmacodynamics, pharmacokinetics, safety, and immunogenicity of candidate biosimilar CT-P41 relative to US reference denosumab. CT-P41 had equivalent efficacy and pharmacodynamics to US-denosumab, with similar pharmacokinetics and comparable safety and immunogenicity profiles. PURPOSE: To demonstrate equivalence of candidate biosimilar CT-P41 and US reference denosumab (US-denosumab) in postmenopausal women with osteoporosis. METHODS: This 78-week (18-month), double-blind, randomized, active-controlled Phase 3 study (NCT04757376) comprised two treatment periods (TPs). In TPI, patients (N = 479) were randomized 1:1 to 60 mg subcutaneous CT-P41 or US-denosumab. At Week 52, those who had received CT-P41 in TPI continued to do so. Those who had received US-denosumab were randomized (1:1) to continue treatment or switch to CT-P41 in TPII. The primary efficacy endpoint was percent change from baseline in lumbar spine bone mineral density at Week 52. Efficacy equivalence was concluded if associated 95% confidence intervals (CI) for least squares (LS) mean group differences fell within ± 1.503%. The primary pharmacodynamic (PD) endpoint was area under the effect curve for serum carboxy-terminal cross-linking telopeptide of type I collagen through the first 26 weeks, with an equivalence margin of 80-125% (for 95% CIs associated with geometric LS mean ratios). RESULTS: Equivalence was demonstrated for CT-P41 and US-denosumab with respect to primary efficacy (LS mean difference [95% CI]: - 0.139 [- 0.826, 0.548] in the full analysis set and - 0.280 [- 0.973, 0.414] in the per-protocol set) and PD (geometric LS mean ratio [95% CI]: 94.94 [90.75, 99.32]) endpoints. Secondary efficacy, PD, pharmacokinetics, and safety results were comparable among all groups up to Week 78, including after transitioning to CT-P41 from US-denosumab. CONCLUSIONS: CT-P41 was equivalent to US-denosumab in women with postmenopausal osteoporosis, with respect to primary efficacy and PD endpoints.
ABSTRACT
The PAH1-encoded phosphatidate (PA) phosphatase is a major source of diacylglycerol for the production of the storage lipid triacylglycerol and a key regulator for the de novo phospholipid synthesis in Saccharomyces cerevisiae. The catalytic function of Pah1 depends on its membrane localization which is mediated through its phosphorylation by multiple protein kinases and dephosphorylation by the Nem1-Spo7 protein phosphatase complex. The full-length Pah1 is composed of a catalytic core (N-LIP and HAD-like domains, amphipathic helix, and the WRDPLVDID domain) and non-catalytic regulatory sequences (intrinsically disordered regions, RP domain, and acidic tail) for phosphorylation and interaction with Nem1-Spo7. How the catalytic core regulates Pah1 localization and cellular function is not clear. In this work, we analyzed a variant of Pah1 (i.e., Pah1-CC (catalytic core)) that is composed only of the catalytic core. Pah1-CC expressed on a low-copy plasmid complemented the pah1Δ mutant phenotypes (e.g., nuclear/ER membrane expansion, reduced levels of triacylglycerol, and lipid droplet formation) without requiring Nem1-Spo7. The cellular function of Pah1-CC was supported by its PA phosphatase activity mostly associated with the membrane fraction. Although functional, Pah1-CC was distinct from Pah1 in the protein and enzymological properties, which include overexpression toxicity, association with heat shock proteins, and significant reduction of the Vmax value. These findings on the Pah1 catalytic core enhance the understanding of its structural requirements for membrane localization and activity control.