Comparison of lapatinib and trastuzumab in patients with HER-2 receptor positive breast cancer

This study aimed to compare lapatinib (Tykerb) and trastuzumab (Herceptin) in patients with HER-2 receptor positive breast cancer. This study found that in patients with hormone receptor-positive tumors, use of lapatinib for 6 months, followed by trastuzumab for 12 months significantly improved survival compared with trastuzumab alone.

Breast cancer is classified into different subtypes depending on the presence or absence of certain receptors (proteins found on the surface of the cancer cells). These subtypes influence treatment options, and also directly affect disease prognosis. Hormone receptor (HR) positive cancer grows in response to female hormones such as estrogen. Another protein that influences breast tumor growth is HER-2. Breast cancer with no receptor proteins on it is called hormone receptor-negative.

Hormones and HER-2 can be targeted by medical treatment. Trastuzumab (TRAS) and lapatinib (LAP) are medications that target HER-2. Treatments such as aromatase inhibitors (AI) target hormones such as estrogen. It is known that HER-2 and HR targeting treatments used together are a good option for HER-2, HR-positive metastatic (spread) breast cancers. 

It is unclear which treatment, lapatinib or trastuzumab, is superior when added to chemotherapy. 

615 patients with HER2-positive tumors received chemotherapy. This was in combination with either lapatinib or trastuzumab during chemotherapy. Afterwards, patients received follow-up trastuzumab for a total of 12 months in the lapatinib arm or 18 months in the trastuzumab arm. Patients were then followed up for 55 months.

Three-year disease-free survival and overall survival were not significantly different between the two treatment arms. No difference was observed in hormone receptor-negative patients.

In patients with hormone receptor-positive tumors, prolonged anti-HER2 treatment (lapatinib for 6 months, followed by trastuzumab for 12 months) significantly improved survival compared with treatment with trastuzumab alone.

This study found that, in patients with hormone receptor-positive tumors, use of lapatinib for 6 months, followed by trastuzumab for 12 months significantly improved survival compared with trastuzumab alone.

Many of the overall survival figures were not statistically significant. More study with larger numbers of patients are required, however these are still promising results.