Comparing the effectiveness and safety of immune checkpoint inhibitors plus chemotherapy versus chemotherapy alone for triple-negative breast cancer.

This study compared the effectiveness and safety of immune checkpoint inhibitors (ICI) plus chemotherapy versus chemotherapy alone for the treatment of patients with triple-negative breast cancer (TNBC). The data showed that ICI plus chemotherapy was more effective than chemotherapy alone and was associated with a higher rate of side effects in patients with TNBC.

Triple-negative breast cancer (TNBC) is a subtype of breast cancer (BC) that tests negative for female hormone receptors (estrogen and/or progesterone) and the HER2 protein. TNBC accounts for 10-15% of all BCs. It is associated with a poorer disease outcome compared to other subtypes of BC. Treatments for TNBC usually involve a combination of surgery, chemotherapy, and radiotherapy.

Immunotherapy uses the body’s own immune system to fight cancer. Immune checkpoint inhibitors (ICIs) are a type of immunotherapy used to treat a wide variety of cancers. Tumor cells try to avoid death by switching off our immune system. ICIs such as pembrolizumab (Keytruda) work by blocking the off switch of the immune system. This inhibition triggers the immune system to attack tumor cells and kill them. Pembrolizumab has been approved for use as a first-line treatment in metastatic TNBC. However, there are very few studies comparing the effectiveness and safety of ICI plus chemotherapy versus chemotherapy alone for the treatment of patients with TNBC.

This study analyzed 9 studies that involved 4501 patients with TNBC. Patients were divided into 2 groups. Group 1 included 2645 patients who received ICI plus chemotherapy. Group 2 included 1856 patients who received chemotherapy alone.

Patients in group 1 were 14% more likely to have a better survival compared to patients in group 2. Patients in group 1 were 22% more likely to survive without cancer worsening compared to patients in group 2.

52.8% of the patients in group 1 achieved a complete response (CR; complete disappearance of cancer cells) compared to 41.3% of the patients in group 2. Patients in group 1 were 1.38 times more likely to achieve a CR compared to patients in group 2.

The addition of ICIs to chemotherapy might not have a better effect in Asian patients, patients with locally advanced disease, or patients with brain metastases.

ICI plus chemotherapy was associated with more risk of side effects compared with chemotherapy alone. The most common side effects associated with the addition of ICIs to chemotherapy were diarrhea, severe skin reactions, and inflammation of the lung and liver.

This study concluded that ICI plus chemotherapy was more effective than chemotherapy alone and was associated with a higher rate of side effects in patients with TNBC.

The treatments used in the ICI plus chemotherapy group and chemotherapy group were different between the groups. Only studies published in English were included. More studies are needed to validate the conclusions.