Prestige Biopharma Announces Positive Topline Results from Comparative SAMSON-II Study for HD204, a Potential Biosimilar to Avastin (bevacizumab)

Primary endpoint of Overall Response Rate at Week 18 met, demonstrating clinical equivalence in patients with advanced non-squamous non-small cell lung cancer

SINGAPORE, March 24, 2026 /PRNewswire/ -- Prestige Biopharma today announced positive topline results from its Phase 3 SAMSON-II study evaluating HD204, a proposed biosimilar to Avastin^® (bevacizumab) in adult patients with advanced non-squamous non-small cell lung cancer (NSCLC).

SAMSON-II is a randomized, double blind, parallel group, multicenter Phase 3 study conducted in 625 patients across 91 centers in 15 countries. Patients were randomized in a 1:1 ratio to receive HD204 or Avastin in combination with standard chemotherapy.

The study met its primary endpoint of overall response rate (ORR) at Week 18, demonstrating clinical equivalence between HD204 and Avastin within the prespecified equivalence margin. ORR at Week 18 was 48.7% in the HD204 arm compared with 46.5% in the Avastin arm. The risk ratio was 1.047 (95% confidence interval [CI]: 0.86–1.27), and the risk difference was 0.022 (95% CI: −0.07–0.11), with both estimates falling within the predefined equivalence range.

Secondary efficacy endpoints were supportive of the primary analysis. Comparable overall response rates were observed at Week 12, and time-to-event outcomes demonstrated similar progression-free survival (PFS) and overall survival (OS) between treatment groups, with no statistically significant differences identified.

HD204 demonstrated a safety and tolerability profile consistent with the established safety experience of bevacizumab. Treatment-related adverse events were reported in 33.9% of patients receiving HD204 and 34.4% of patients receiving Avastin, while treatment-related serious adverse events occurred in 5.2% and 8.3% of patients, respectively. No new or unexpected safety signals were identified.

The clinical outcomes observed in SAMSON-II were consistent with the high degree of analytical and clinical pharmacokinetic (PK) similarity demonstrated between HD204 and Avastin. SAMSON-II results strengthen the collective global experience showing that sensitive analytical characterization and comparative clinical PK studies can reliably predict equivalent clinical performance in biosimilar development. Prestige Biopharma is advancing regulatory pathways for HD204 based on the strong analytical and clinical PK programs, while sharing the SAMSON-II findings to further contribute to the global scientific experience in biosimilar evaluation.

"These results illustrate the increasing precision with which biosimilarity can be established through advanced analytical and clinical PK studies," said Dr. Lisa Park, Chief Executive Officer of Prestige Biopharma. "Our experience with HD204 supports the view that well-designed development programs can reliably anticipate clinical performance, enabling more focused and efficient biosimilar development. By reducing unnecessary clinical burden, such advances can accelerate patient access to high-quality biologic medicines and support more sustainable healthcare systems worldwide."