Week 4, September 2025: Global Momentum in Antibody Biosimilars

Monoclonal antibodies (mAbs) for clinical use typically have high efficacy and favorable tolerability due to selective antigen targeting. However, their complex structure, especially as glycoproteins produced in diverse cellular systems, makes them expensive to manufacture, limiting patient access. These cost and accessibility challenges have fueled the development of biosimilars: biologic products designed to be copies of the reference mAb, but are often slightly different in pharmacodynamic and pharmacokinetic properties because of changes in glycosylation.

In response to escalating healthcare costs, various global markets have implemented policies to promote biosimilar adoption. For example, Japan mandates an initial biosimilar pricing at 70% of the reference product. Despite this, uptake remains variable, as biosimilar replacement rates range widely, from 90% for filgrastim to just 20% for infliximab. Contributing factors include limited clinical data for minor indications, inconsistent quality information compared to small-molecule generics, and inadequate understanding among healthcare providers and patients. In contrast, regions such as the EU have achieved higher biosimilar penetration through regulatory support and prescriber autonomy; France, for instance, allows automatic substitution of TNFα inhibitors unless explicitly restricted, resulting in replacement rates nearing 80%.

These past few weeks multiple biosimilars have been approved or advanced by regulatory authorities across the U.S., Canada, and Europe, with denosumab emerging as a dominant target molecule. The U.S. FDA recently approved multiple denosumab biosimilars: BILDYOS® and BILPREVDA® from Henlius and Organon, and Bosaya™ and Aukelso™ from Biocon Biologics. All four products are approved for the full range of indications of the reference products, Prolia® and Xgeva®. Notably, the Biocon products received provisional interchangeability status, a regulatory designation that may encourage greater formulary uptake. In Canada, Celltrion’s Stoboclo® and Osenvelt® (CT‑P41) also secured approval for all Prolia/Xgeva indications, supported by robust Phase III data. In Europe, the EMA has issued positive CHMP opinions for both Alvotech’s AVT03 (denosumab biosimilar) and Gobivaz® (golimumab biosimilar), with commercialization planned through regional partners including STADA, Dr. Reddy’s, and Advanz Pharma.

Meanwhile, earlier this month, a groundbreaking milestone for pharmaceutical innovation was achieved when Prof. Sarfaraz K. Niazi secured the first-ever FDA acceptance to waive clinical efficacy studies (CESs) for monoclonal antibody biosimilars. Professor Niazi advocated that CESs add no scientific value to biosimilar evaluation, as analytical similarity and immunogenicity studies are sufficient to confirm biosimilarity. Thus, the biosimilar application for Stelara (ustekinumab) will be the first filed with the FDA without requiring any clinical testing, marking a precedent-setting regulatory breakthrough.