AstraZeneca on Wednesday said two experimental breast cancer drugs showed promise in separate clinical trials, succeeding in areas where the British drugmaker’s rivals have fallen short.
One drug, called capivasertib, met both of its goals in a Phase 3 trial of patients with breast cancer whose tumors are hormone positive, but have low or no detectable levels of a protein called HER2. The other, camizestrant, achieved its objective in a smaller, Phase 2 study of post-menopausal patients with metastatic, estrogen receptor-positive disease.
AstraZeneca didn’t disclose specific data in statements announcing the study outcomes. The company will present further details at an upcoming medical meeting and, for capivasertib, share the results with health regulators.
The positive findings could position the two drugs to become new treatments for tumors that represent about 70% of diagnosed breast cancer cases. Typically, these tumors are initially treated with hormone therapy or newer types of drugs known as CDK4/6 inhibitors, but cancer cells can develop resistance to these treatments over time.
The trial outcomes are also notable for how they contrast with results for similar, competing drugs.
Capivasertib blocks an enzyme known as AKT that is part of a signaling pathway involved in a variety of cellular functions such as growth and survival. That signaling goes haywire in breast cancer, making AKT a target for new therapies and a potential way to improve on standard treatments. Several drug candidates have emerged in recent years. However, the most advanced, Roche’s ipatasertib, failed multiple trials in front-line breast cancer.
AstraZeneca’s study differed from those trials, enrolling patients whose disease had progressed or recurred after at least one treatment. The drug was also tested alongside the decades-old hormone therapy fulvestrant, whereas the Roche trials that have read out involved chemotherapy and immunotherapy.
AstraZeneca didn’t describe the magnitude of benefit with its drug, but did note the combination kept tumors from spreading longer than fulvestrant alone. Though early, survival data are “encouraging,” AstraZeneca said, adding that the drug’s safety profile was similar to what’s been reported previously.
Camizestrant, meanwhile, is one of a group of medicines that are meant to be safer and more convenient than fulvestrant, which is widely prescribed for breast cancer patients whose disease is driven by hormones. These drugs, known as SERDs for short, block and degrade hormone receptor proteins and are administered as pills. The hope is that they could replace fulvestrant, but study results to date have been mixed.
Drugs from Roche and Sanofi each failed in clinical testing, while a similar drug developed by Radius Health and licensed to Menarini Group succeeded. That drug, elacestrant, is currently being reviewed by the Food and Drug Administration. (A fourth medicine from Eli Lilly is in late-stage testing.)
Unlike Sanofi and Roche, Radius included patients with a tumor mutation called ESR1 who may have played a role in that trial’s success. AstraZeneca didn’t, though it’s unclear how big an impact the drug had. Camizestrant is currently in two Phase 3 studies in breast cancer, one of which, SERENA-6, could produce results next year, according to a clinical trials database.
The positive readouts follow AstraZeneca’s success with another breast cancer drug called Enhertu, which recently became the first treatment specifically approved for people with so-called HER2-low tumors.