A Phase 3 clinical trial has confirmed that SB17, a proposed biosimilar to ustekinumab (Stelara), demonstrates similar efficacy, safety, pharmacokinetics, and immunogenicity in patients with moderate to severe plaque psoriasis. The double-blind, randomized controlled trial, conducted across 45 centers in 8 countries, compared SB17 to the reference product over a 28-week period, marking a significant step toward potentially more accessible treatment options for psoriasis patients.
The study, involving 249 subjects, randomized participants to receive either SB17 or the reference ustekinumab at 0 weeks, 4 weeks, and then every 12 weeks until week 40. The primary endpoint was the percent change from baseline in the Psoriasis Area and Severity Index (PASI) at week 12. The adjusted difference in PASI change from baseline at week 12 was –0.6% (95% CI, –3.780 to 2.579), falling within the pre-defined equivalence margin of –5% to 15%.
Efficacy and Safety Outcomes
The time-response curve of percent change of PASI from baseline was reported as "nearly identical" between the two groups up to week 28. Secondary efficacy endpoints, including Physician's Global Assessment and Dermatology Life Quality Index, were also comparable between the biosimilar and reference product groups, reinforcing the similarity in clinical outcomes.
Regarding safety, the overall incidence of treatment-emergent adverse events (TEAEs) was 48% in the SB17 group and 49% in the reference product group. Most TEAEs were mild to moderate and not considered related to the study drugs. The most frequently reported TEAEs included nasopharyngitis, COVID-19, and upper respiratory tract infections. Six participants (2.4%) in the biosimilar group and 3 (1.2%) in the reference product group experienced serious TEAEs, but none were attributed to the study drugs.
Immunogenicity and Pharmacokinetics
The pharmacokinetic profiles were generally comparable between the two groups. Interestingly, the incidence of anti-drug antibodies (ADAs) was lower in the SB17 group (13%) compared to the reference product group (39%), with neutralizing antibodies at 14% and 35%, respectively. The authors noted that despite these differences in immunogenicity, the primary efficacy outcome remained comparable between groups in both ADA-positive and ADA-negative subgroups. They suggested that the difference in ADAs could be attributed to variations between the cell lines used to produce the two monoclonal antibodies.
Implications for Psoriasis Treatment
The introduction of biosimilars like SB17 could potentially lower treatment costs and increase patient access to effective therapies for psoriasis. Ustekinumab, an inhibitor of interleukins 12 and 23, offers an alternative to anti-TNF biologics, with advantages such as less frequent dosing and a potentially better safety profile. The study authors concluded that SB17 demonstrated clinical similarity to the reference ustekinumab up to week 28, with comparable safety and pharmacokinetic profiles, supporting its potential as a biosimilar option for patients with moderate to severe plaque psoriasis.
