- An experimental breast cancer drug developed by Roche failed a Phase 2 trial, the company announced Monday, marking the second stumble in as many months for a closely watched group of medicines known as selective estrogen receptor degraders, or SERDs.
- Roche tested the therapy, known as giredestrant, against one of two approved drugs in breast cancer patients whose disease has progressed after a single treatment. The drug didn't keep tumors in check, or meaningfully extend lives, longer than the other medicines, according to a statement. Still, Roche isn't giving up on giredestrant, pointing to positive signs observed in a subgroup of patients.
- Roche's treatment is one of as many as 10 SERDS in development. One experimental treatment from Radius Health has succeeded in Phase 3 testing, whereas a rival Sanofi drug failed in a late-stage study in March.
Since its approval in 2002, fulvestrant, first marketed as Faslodex by AstraZeneca, has become a widely used treatment for breast cancer patients whose disease is driven by hormones. But fulvestrant, which blocks and degrades hormone receptor proteins, has notable limitations, including side effects like liver damage that can curtail its use.
Drugmakers have long aimed to do better, and their efforts have led to a new generation of SERDs taken as daily pills rather than a monthly injection like fulvestrant. Companies including Roche, Sanofi and Eli Lilly have been hoping the additional convenience, and fewer side effects, might give their drugs an advantage.
That quest has been met with several setbacks over the years. Optimism grew when Radius Health's drug succeeded in a pivotal trial last year. Sanofi and Roche's failures have renewed skepticism, however, ahead of additional trial readouts from Eli Lilly and AstraZeneca.
Still, missing its primary goal in a Phase 2 trial may not necessarily be the end of the road for giredestrant. In a statement, Roche pointed to promising data "in patients with higher dependence on estrogen receptor activity." Radius Health's drug appeared to perform best in that subgroup of breast cancer patients, and Roche has additional trials ongoing. Giredestrant, like many SERDs, is being tested in combination with approved breast cancer drugs like Ibrance and Kisqali.
Those studies are gaining a great deal of attention from breast cancer specialists, who view the combination regimens as potential first-line treatments that could compete with hormone-blocking drugs.