Sorrento Therapeutics announced that its partner, MabTech, has successfully completed Phase 3 clinical trials in China for STI-001, a biosimilar antibody for cetuximab (Erbitux). STI-001 is for the treatment of EGFR-expressing metastatic colorectal carcinoma, and STI-002, a biosimilar antibody for infliximab (Remicade), for the treatment of rheumatoid arthritis (RA).

STI-001, in combination with irinotecan, was evaluated in a double-blind, randomized Phase 3 clinical trial in 501 patients with EGFR-expressing metastatic colorectal carcinoma vs. irinotecan alone. The combination therapy showed significant improvement in Overall Response Rate (ORR: 32.9% vs. 12.8%) and Progress-free Survival (PFS: 5.6 vs. 3.2 months) as well as longer Overall Survival (OS: 14.1 vs. 13.4 months) vs. irinotecan alone. All three endpoints for STI-001 plus irinotecan were significantly greater than previously reported in similar medical settings using Erbitux and irinotecan combination (32.9% vs. 10%; 5.6 vs. 4 months; 14.1 vs. 11.6 months, respectively). Adverse events (AEs), especially Grade 3 and 4, for STI-001 were found to be significantly fewer than those previously reported using Erbitux.

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The Phase 3 study for STI-002 (3mg/kg) plus methotrexate (MTX) in 330 RA patients demonstrated improvements in patients’ pain symptoms, functions, quality of life and inflammation markers while also inhibiting bone and joint injuries. In addition, the combination therapy also demonstrated significant improvement in ACR 20, 50 and 70 (77%, 50% and 20% respectively), similar efficacy data reported for Remicade and biosimilars of Remicade. The study also found significantly reduced immunogenicity and anti-drug antibody formation (ADA) for STI-002 vs. Remicade (<5% vs. ~40%).

STI-001 is a chimeric monoclonal antibody that binds to the epidermal growth factor receptor (EGFR). STI-002 is a chimeric monoclonal antibody that neutralizes the biological activity of tumor necrosis factor α (TNFα) by binding to soluble and transmembrane forms of TNFα and inhibiting its binding to receptors. Both are produced in CHO cell line, contributing to significantly reduced immunogenicity and hypersensitivity reactions.

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