Celltrion presented additional data from a Phase III randomized controlled trial (RCT) for CT-P41, a biosimilar candidate referencing PROLIA/XGEVA (denosumab) in postmenopausal women with osteoporosis (PMO) and a Phase III RCT for CT-P47, a biosimilar candidate referencing ACTEMRA (tocilizumab) in patients with moderate-to-severe active rheumatoid arthritis (RA) at the American College of Rheumatology (ACR) Convergence 2024 in Washington, D.C. The additional efficacy and safety results from Week 52 to Week 78 including switching data from reference denosumab to the CT-P41 (Treatment Period [TP] II) showed comparable and sustained efficacy results to reference denosumab in treating women with PMO after the single transition from reference denosumab to CT-P41. CT-P41 was well tolerated with a safety profile comparable to reference denosumab, and no notable safety issue was identified following the single transition compared with maintenance groups up to Week 78. The results further support the biosimilarity between CT-P41 and reference denosumab in treating women with PMO.

In addition, post-hoc impact analysis using data from the Phase III RCT was conducted to determine any correlation between immunogenicity and clinical outcomes in PMO between the treatment groups. According to the results, the impact of anti-drug antibody (ADA) on pharmacokinetics (PK), efficacy and safety and the treatment emergent adverse events (TEAE) incidences were comparable between the treatment groups in the ADA status groups. Despite the high ADA incidence compared to the reference denosumab historical studies, it can be suggested that ADA to CT-P41 and reference denosumab has no clinical impact considering the high sensitivity and specificity of the assay and further evaluation of immunogenicity impact.

Results of the single transition from the reference tocilizumab to CT-P47 from a Phase III RCT were also presented at the ACR. The 1-year results showed that CT-P47 had comparable and sustained efficacy, safety and immunogenicity profiles in patients with active moderate-to-severe rheumatoid arthritis (RA) compared to the reference tocilizumab even after switching. These data further support biosimilarity of CT-P47.