Trastuzumab emtansine with or without pertuzumab versus trastuzumab with taxane for HER2+ advanced breast cancer

This study wanted to find out which treatment resulted in better overall survival for patients with HER2+ breast cancer; trastuzumab emtansine (Kadcycla) with or without pertuzumab (Perjeta), or trastuzumab (Herceptin) plus a taxane. The study found that the overall survival was similar across all groups. 

There are many treatment options for breast cancer. HER2+ breast cancer can be targeted by certain medications. The standard care for advanced HER2+ breast cancer is trastuzumab and pertuzumab, plus a taxane medication. Taxanes are chemotherapy drugs such as docetaxel (Taxotere) or paclitaxel (Taxol).

Trastuzumab emtansine (T-DM1) combines trastuzumab with DM1. This is a molecule that specifically targets cancer cells and reduces the side effects to normal cells.

It is not known if treating patients with advanced HER2+ breast cancer using TDM-1 with or without pertuzumab will mean a higher chance of survival in these patients compared to trastuzumab and a taxane. 

The study had 1095 patients. All of the patients had advanced HER2+ breast cancer. The patients were split into three groups for treatment. Group A was treated with TDM-1 and a placebo. Group B was treated with TDM-1 plus pertuzumab. Group C was treated with trastuzumab and a taxane. The patients were followed for an average of 42 months after treatment ended. 

The overall length of survival was similar across all groups. On average, patients in group A survived for 53.7 months. On average, patients in group B survived for 51.8 months. On average, patients in group C survived for 50.9 months. In patients who had tumor shrinkage, the average survival was longer for groups A and B than for group C.

In some of the patients, side effects were experienced. These included hair loss, diarrhea, fever, and issues with blood levels. Side effects were more likely in the patients in group C (55.8%), compared to group A (47.1%) and group B (48.6%). 

The study concluded that treatment with TDM-1 with or without pertuzumab is a good option for patients with HER2+ advanced breast cancer. 

This study involved an ongoing analysis from a long-term trial. This study was funded by F. Hoffmann–La Roche, Ltd, the manufacturer of T-DM1, trastuzumab, and pertuzumab.