VANCOUVER, B.C. – Amgen’s recent announcement that it is pulling the plug on further development of the investigational interleukin-17 receptor A inhibitor brodalumab was the red hot topic among psoriasis experts at the World Congress of Dermatology.

The biologic agent had seemingly been breezing through phase III clinical trials, racking up head-turning efficacy and reasonable safety numbers in a series of very large randomized studies conducted in patients with moderate-to-severe chronic plaque psoriasis. Then came the surprise announcement a scant couple of weeks before WCD 2015.

Brodalumab was also in codevelopment by Amgen and AstraZeneca for psoriatic arthritis and axial spondyloarthritis. Amgen is halting all participation in those research projects as well.

The company’s decision was based upon preliminary indications from the Food and Drug Administration that, as a condition for marketing approval, there would likely need to be restrictive labeling calling for physician monitoring for suicidality, something few dermatologists or rheumatologists are comfortable with.

“During our preparation process for regulatory submissions, we came to believe that labeling requirements likely would limit the appropriate patient population for brodalumab,” Dr. Sean E. Harper, executive vice president of research and development at Amgen, said in the company’s announcement.

AstraZeneca officials said in a separate statement that they will review all the brodalumab data in detail and make a decision as soon as possible regarding whether to pursue unilateral development of the biologic agent.

Dr. Richard G. Langley, who at WCD 2015 presented the results of the AMAGINE-3 trial – 1,881 psoriasis patients randomized to ustekinumab (Stelara) at the approved dosing, placebo, or brodalumab at either 140 mg or 210 mg subcutaneously – noted that rates of depression and suicidal ideation were similarly low in the ustekinumab and brodalumab groups during the 52-week study, and there were no suicide attempts.

The problem for Amgen was a single-digit numeric imbalance in these adverse events in some of the earlier, considerably smaller studies of brodalumab, according to Dr. Langley, professor of dermatology at Dalhousie University in Halifax, Nova Scotia.

“We have to remember that we can sometimes make spurious assumptions about rare events and perhaps cast a shadow on a pathway or molecule before we have full information,” he said diplomatically. “The Amgen decision is particularly unfortunate for patients because with brodalumab the only patients I’ve had who were depressed were the ones I’ve told are now no longer going to get the medication.”

Session chair Dr. Yves Poulin of Laval University in Quebec City, Quebec, said his experience has been similar: Patients love the unprecedented effectiveness of brodalumab and are crestfallen at learning they have to go off it.

Indeed, in AMAGINE-3, the 12-week PASI 75 rate among patients on brodalumab at 210 mg every 2 weeks – the more effective dose of the IL-17A inhibitor – was 85.1%, compared with 69.2% for ustekinumab, which is one of the most widely prescribed biologics. The PASI 100 rate was 36.7% for brodalumab, twice the 18.5% rate with ustekinumab. And the Investigator’s Global Assessment rating of 0 or 1 – clear or almost clear – was 79.6% with brodalumab, compared with 59% for ustekinumab, Dr. Langley reported.

“A consistent finding with brodalumab and the other IL-17 inhibitors is the remarkably fast improvement: within the first 2-4 weeks there’s a robust response,” he added.

Elsewhere at WCD 2015, Dr. Alan Menter presented the findings of the AMAGINE-2 trial, an 1,831-patient study identical in design to AMAGINE-3. The efficacy and safety results were virtually the same as in AMAGINE-3 as well, both in the 12-week induction phase and out to 52 weeks.

“We have a major issue that I think people haven’t understood well over the years relating to depression and psoriasis. Suicidal ideation has always been an issue. If you’re a 25-year-old and you’re trying to make your way in life and you’ve got significant psoriasis, you’re going to get depressed. But the suicidal ideation is twice as high in young people with psoriasis at baseline than in all the other autoimmune diseases put together,” said Dr. Menter, chair of dermatology at Baylor University Medical Center, Dallas, and the founding president of the International Psoriasis Council.

There has been no suicidality signal with secukinumab (Cosentyx), which in January became the first and, to date, only IL-17 inhibitor approved for marketing, nor with ixekizumab, which is in phase III clinical trials. There are distinct differences between the IL-17 inhibitor molecules – for example, brodalumab is IgG2, secukinumab is IgG1, and ixekizumab is IgG4. And brodalumab is a receptor antibody that not only inhibits the activity of IL-17A, but of IL-17F and -E as well, whereas secukinumab and ixekizumab work by other mechanisms. Investigators are now taking a close look at these differences to see if they have effects in terms of clinical outcomes and side effect profiles, he said.

Dr. Langley and Dr. Menter reported having financial relationships with Amgen and numerous other pharmaceutical companies.

bjancin@frontlinemedcom.com

Amgen’s termination of brodalumab stuns psoriasis world