Can abemaciclib plus hormonal therapy be considered a safe and effective treatment in older patients with advanced breast cancer?

This article looked at the safety and effectiveness of abemaciclib (Verzenios) plus hormonal therapy (HT) in older patients with hormone receptor-positive (HR+)/HER-2 negative (HER2-) advanced breast cancer (BC). The authors concluded that abemaciclib + HT was effective across all age groups and while higher rates of side effects were reported in older patients, these were manageable with dose changes.

BC is one of the leading causes of cancer in women worldwide. Patients over 65 years are more likely to develop BC. Having a HR+ cancer means that the cancer cells express on their surface proteins that can attach to the female sex hormones estrogen or progesterone. These hormones can help the cancer to grow. HR+ BCs are commonly treated with HT that blocks the action of these hormones on cancer cells. Having HER2- cancer means cancer cells do not have the HER2 protein on their surface. This form of BC can be difficult to treat.

Abemaciclib is a biological therapy that targets certain proteins involved in the cell cycle. This slows the rate of cancerous cells spreading. Previous studies have shown that abemaciclib combined with HT improves the outcomes of patients with HR+/HER2- advanced BC. However, if this effect is the same in all age groups is unknown.

There were 1162 patients with advanced HR+/HER2- BC from 2 clinical trials included in this study. Patients received either abemaciclib or a placebo with a HT drug such as fulvestrant (Faslodex), anastrozole (Nolvadex), or letrozole (Femara). Patients were divided into 3 groups. Group 1 included patients younger than 65 years. Group 2 included those aged between 65-74 years and group 3 included patients aged 75 or older. 

Abemaciclib added to HT improved the survival without cancer worsening compared to HT alone in all age groups. There was no significant difference among the 3 age groups in survival without cancer worsening in patients treated with abemaciclib and HT.

Side effects were experienced at a higher rate in the abemaciclib groups compared to the placebo groups. Diarrhea, low white blood cell counts, nausea, and tiredness were the most common side effects reported in abemaciclib-treated patients. Nausea and lower appetite were 10-20% more common in groups 2 and 3 treated with abemaciclib. Blot clots in the veins were also more common in group 3. There was a slightly higher need to change doses or stop treatments in older patients.

The authors concluded that abemaciclib and HT was effective in treating advanced HR+/HER2- BC across all age groups. Older patients tended to experience more side effects, however, these were manageable through dose adjustments. 

This study was funded by Eli Lilly, the manufacturer of abemaciclib.