Evaluating the effectiveness and safety of elacestrant versus standard hormonal therapy in patients with ER+/HER2- advanced BC.

This study evaluated the effectiveness and safety of elacestrant (RAD1901) versus standard hormonal therapy in patients with estrogen receptor-positive (ER+) and HER2-negative (HER2-) advanced breast cancer (BC). The data showed that elacestrant significantly improved survival without cancer worsening with manageable side effects in these patients.

BC is classified into different subtypes depending on the presence or absence of certain receptors (proteins found on the surface of the cancer cells). ER+ and HER2- BC tests positive for the estrogen receptor (female sex hormones) and negative for the HER2 protein. This means BC grows in response to the estrogen hormone. This type of cancer accounts for 70% of all BCs. The current standard treatment for this subtype of BC is to use hormonal therapy with either an aromatase inhibitor (AI) or fulvestrant (Faslodex). However, some patients have disease progression with this treatment. For these patients, newer treatments are needed.

Elacestrant is a newer drug that can be taken orally and works in a similar way as fulvestrant. It blocks the action of the estrogen hormone on cancer cells. This stops cancer cell growth. However, the effectiveness and safety of elacestrant versus standard hormonal therapy in patients with ER+/HER2- advanced BC is still unknown.

This study involved 477 women with ER+/HER2- advanced BC. Patients were randomly assigned into 2 groups. Group 1 included 239 patients who received elacestrant. Group 2 included 238 patients who received standard-of-care (SOC) hormonal therapy. The average follow-up time was 15.1 months.

After 12 months, 22.3% of the patients in group 1 were alive without cancer worsening versus 9.4% of the patients in group 2. Patients in group 1 were 30% more likely to survive without cancer worsening than patients in group 2.

In patients with an ESR1 (estrogen receptor) mutation, after 12 months, 26.8% of the patients in group 1 were alive without cancer worsening versus 8.2% of the patients in group 2. Patients in group 1 were 45% more likely to survive without cancer worsening than patients in group 2.

Treatment-related side effects occurred in 7.2% of the patients in group 1 versus 3.1% of the patients in group 2. 3.4% of the patients in group 1 stopped treatment due to side effects compared to 0.9% of the patients in group 2. The most common side effect was nausea (35% in group 1 vs 18.8% in group 2).

This study concluded that elacestrant significantly improved survival without cancer worsening with manageable side effects in patients with ER+/HER2- advanced BC.

This study was sponsored by Radius Health Inc., the manufacturer of elacestrant. Elacestrant is currently being reviewed for FDA approval for the treatment of patients with ER+/HER2- advanced BC.