New treatment improves tumor response in patients with HER2 positive metastatic colorectal cancer

This study investigated the effectiveness of pertuzumab (Perjeta) and trastuzumab (Herceptin) in patients with colorectal cancer and HER2 mutation (an abnormal gene). Researchers suggested that this treatment could be a safe option for patients with metastatic (spread to other parts of the body) colorectal cancer (mCRC).

Colorectal cancer is one of the leading causes of death worldwide. The HER2 mutation is associated with increased growth of tumor cells. This is found in 2 to 6 % of the patients with mCRC.

Prior studies showed that targeted therapies such as trastuzumab or pertuzumab can improve the outcomes of patients with mCRC by stopping tumor growth. It is still not clear how treatment with the combination of trastuzumab and pertuzumab can affect patients with HER2 positive mCRC.

This study included 57 patients with HER2 positive mCRC. Most patients previously received an average of 2-5 treatment regimens. These patients received pertuzumab and trastuzumab every three weeks. The tumor response rate was measured.

One patient (2%), out of 57, had a complete response (complete disappearance of all signs of cancer). 17 (30%) patients had a partial response (tumor shrinkage). 44% of patients had controlled disease (tumor not shrinking, nor growing).

The most common side effects were diarrhea (33%), fatigue (32%) and nausea (30%). Severe side effects such as low levels of potassium in the blood were seen in 37% of the patients. There were no treatment-related deaths.

This study concluded that therapy with pertuzumab and trastuzumab improves tumor response in patients with HER2 positive mCRC, with manageable side effects.

This study included a small number of participants and had a short follow-up. The study received funding from F Hoffmann-La Roche/Genentech, the manufacturers of pertuzumab and trastuzumab.