A trial looking at trastuzumab emtansine for HER2 positive breast cancer (TH3RESA)

Cancer type:

Breast cancer

Status:

Results

Phase:

Phase 3

This trial was for people whose breast cancer has spread to the surrounding tissue (locally advanced) or to another part of the body (secondary breast cancer). They had already had treatment with both trastuzumab (Herceptin) and lapatinib.

More about this trial

Some breast cancers have large amounts of a protein called HER2 Open a glossary item on the surface of the cells. These cancers are HER2 positive. They can be treated with drugs that target the HER2 protein including:

trastuzumab (Herceptin)
pertuzumab
lapatinib

People can also be treated different types of chemotherapy, including a drug called a taxane Open a glossary item .

Trastuzumab emtansine is a combination of trastuzumab and the chemotherapy drug, DM1. Trastuzumab finds the cancer cells and delivers the DM1 to them. This type of drug is called a conjugated monoclonal antibody.

The aim of this trial was to find out how well trastuzumab emtansine works for people with HER2 positive breast cancer

whose cancer has spread into the surrounding tissue (locally advanced) or elsewhere in the body (secondary or advanced breast cancer)

and

they have already been treated with both trastuzumab and lapatinib and their cancer has got worse

Summary of results

The people who took part in this trial had HER2 positive advanced breast cancer previously treated with trastuzumab, lapatinib and a taxane chemotherapy. The researchers found that trastuzumab emtansine worked well for this group of people.

602 people took part in the trial.

404 had trastuzumab emtansine
198 had treatment recommended by their doctor

TH3RESA trial diagram

The researchers looked at the length of time it took before people’s cancer got worse. This is called progression free survival. This was:

just over 6 months (6.2) in the group having trastuzumab emtansine
just over 3 months (3.3) in the group having treatment recommended by their doctor

The researchers also looked at the length of time people lived after treatment. This is called overall survival. This was:

just under 23 months (22.7) in the group having trastuzumab emtansine
just under 16 months (15.8) in the group having treatment recommended by their doctor

They looked at the side effects people had in both groups and how severe these side effects were. People having trastuzumab emtansine had less severe side effects.

The most common side effects of trastuzumab emtansine were:

tiredness (fatigue)
weakness and lacking energy
a reduction in the number of platelets in the blood (thrombocytopenia), these help the blood to clot

The most common side effects from the treatment chosen by doctors included:

tiredness (fatigue)
a reduction in the number of white blood cells in the blood (neutropenia), these help to fight infection
diarrhoea

The researchers concluded that trastuzumab emtansine should be used as a standard treatment Open a glossary item for people with advanced HER 2 positive breast cancers who have had previous treatment.