- An experimental drug from Amgen and AstraZeneca has come up short in a late-stage study of patients with severe asthma who frequently require corticosteroids, dealing a blow to a treatment which just last month found success in a different asthma trial.
- The failed study, known as SOURCE, enrolled 150 patients who need standard-of-care therapy as well as oral and inhaled corticosteroids to keep their asthma in check. Participants stayed on their currently prescribed standard-of-care and inhaled steroid regimens, then received either a placebo or Amgen's drug, tezepelumab. Results show that after 48 weeks, patients on tezepelumab didn't perform significantly better than the placebo group on the study's main goal: a reduction in the daily oral corticosteroid dose, without loss of asthma control.
- David Reese, Amgen's head of research and development, called the results "surprising" and said the companies will be exploring them further. "On initial review, the study design may have contributed to the results observed on the primary endpoint," Reese said in a Dec. 21 statement.
Thursday's readout offers the latest twist in what's become a winding journey for tezepelumab, a drug that Amgen has been working on for more than a decade.
In 2012, tezepelumab was wrapped into a deal with AstraZeneca, in which the U.K. drugmaker would help develop and commercialize five of Amgen's experimental drugs for inflammation. One drug from the agreement is now sold by Bausch Health as a plaque psoriasis treatment, under the brand name Siliq.
Yet, that same year, the New England Journal of Medicine published results from a different study, showing that patients with uncontrolled asthma who received tezepelumab ended up having much lower exacerbation rates —meaning less frequent asthma attacks — than patients who weren't treated with the drug.
Those positive effects were recently reinforced, with Amgen announcing last month that tezepelumab succeeded in a large trial called NAVIGATOR, which enrolled nearly 1,100 patients with severe asthma.
Even though the SOURCE trial is much smaller and, according to Amgen, showed promising results beyond oral corticosteroid needs, analysts at Baird still expect its failure will blunt some of the optimism around tezepelumab.
"[W]e expect these results will significantly temper commercial expectations," wrote Baird's Brian Skorney, noting too that tezepelumab's primary competitor, Regeneron and Sanofi's marketed drug Dupixent, was able to reduce corticosteroid use in a similar late-stage study.
Dupixent revenues have grown considerably since the drug's approval to treat asthma in late 2018; over the first nine months of 2020, the drug raked in almost $2.9 billion in net sales.