ISTANBUL, TURKEY – The investigational interleukin-17A inhibitor secukinumab was the talk of Europe’s premier dermatology conference as a result of a series of world-premiere presentations of not one, but three, phase III clinical trials.
The entire secukinumab pivotal phase III program results were presented together at the annual congress of the European Academy of Dermatology and Venereology. Based on these promising results, Novartis plans to file for Food and Drug Administration and European regulatory approval before the end of 2013.
The three randomized, double-blind, multicenter pivotal trials of secukinumab in psoriasis collectively included 3,367 patients with moderate to severe chronic plaque psoriasis. All three studies were strongly positive. Efficacy rates were higher than with current biologics, clinical improvement was remarkably rapid, and the safety profile was reassuring.
"Those of us working in this area of research are really excited by this new data and what it says for the treatment of psoriasis patients," commented Dr. Richard Langley of Dalhousie University, Halifax, N.S.
He presented the centerpiece of this trio of phase III trials, known as the FIXTURE trial. FIXTURE (Full Year Investigative Examination of Secukinumab vs. Etanercept Using 2 Dosing Regimens to Determine Efficacy in Psoriasis) was a 1,306-patient, double-blind, double-dummy trial conducted by 153 investigators in 37 countries. The trial featured a 1-year head-to-head comparison of secukinumab and the widely prescribed tumor necrosis factor (TNF) inhibitor etanercept (Enbrel). The IL-17A inhibitor outperformed etanercept in all of the prespecified primary and secondary outcome measures. Moreover, the two biologics proved equally safe.
"I think it’s interesting in comparing these two molecules that when we look at the data to date, we see comparable safety results. Etanercept is one of the most widely used biologics and has an excellent safety record. That’s reassuring for those of us who are investigating IL-17 signaling," observed Dr. Langley, also the current president of the Canadian Dermatology Association.
FIXTURE participants had a mean baseline Psoriasis Area and Severity Index (PASI) score of 24, an average body mass index of 34 kg/m2, and a mean age in the mid-40s, and were previous inadequate responders to conventional systemic agents and/or biologics. The two co-primary endpoints were 12-week rates of at least a 75% reduction in PASI score, or PASI 75 response, and an Investigator’s Global Assessment (IGA) rating of 0/1, corresponding to clear or nearly clear, on a modified 5-point scale that provides more clinically meaningful information than the older 6-point IGA scale. Patients randomized to the secukinumab 300-mg or 150-mg groups did significantly better on both outcome measures than those assigned to etanercept.
The onset of benefit with secukinumab was swift; a statistically significant improvement compared with etanercept was seen within 2 weeks in terms of IGA scores and within 3 weeks for PASI 75. Secukinumab at 300 mg per subcutaneous injection – the most effective dose across all three pivotal trials – achieved roughly a 50% reduction in PASI scores after 3 weeks, compared with 8 weeks for etanercept, the dermatologist explained.
The PASI 75 response rate at 12 weeks was 77.1% in patients receiving secukinumab at 300 mg, 67% for those receiving secukinumab at 150 mg, 44% for etanercept 50 mg, and 4.9% for placebo.
The highest response rates with secukinumab were seen at week 16 rather than week 12. In the secukinumab 300-mg group, the PASI 75 rate at week 16 was 86.7%, with that high level of response being retained throughout the remainder of the 52-week study. In contrast, the PASI 75 rate at week 16 for etanercept was less than 60%. The IGA 0/1 rate at week 16 was 75.5% in the secukinumab 300-mg group and 60% with secukinumab 150 mg. The peak IGA 0/1 rate in the etanercept arm was only about 45%, and it came much later, at week 26.
Looking at more stringent secondary endpoints, the investigators found that a PASI 90 response was achieved by week 16 in 72.4% of the high-dose secukinumab group, compared with about 30% with etanercept. Twenty-four percent of patients on high-dose secukinumab had a PASI 100 response at week 12, compared with 4% on etanercept. By week 16, 36.8% of the high-dose secukinumab group had a PASI 100 response. At week 52, 65% of the secukinumab 300-mg group maintained a PASI 90 response, compared with 33% of the etanercept group.
The most common adverse event documented in FIXTURE was nasopharyngitis, which occurred in roughly one-third of patients in all four study arms. The serious infection rate was 1%-1.2% in all four study arms. No signals of an increase in malignancies or major adverse cardiovascular events were noted in any of the active treatment groups. Overall, adverse events were similar in both secukinumab arms and comparable to etanercept. Injection-site reactions occurred in 6.1% of the etanercept group and in none of the patients assigned to secukinumab or placebo.