An examination of pertuzumab and trastuzumab as breast cancer treatment before surgery in a real-life setting

This study examined the effectiveness and safety of the drug combination pertuzumab (Perjeta) and trastuzumab (Herceptin) as a treatment for breast cancer (BC) with positive HER2 (human epidermal growth factor receptor 2) before surgery to remove the tumor in a real-world setting.

The data showed that this combination is safe and effective in achieving a complete pathological response (pCR).

After the diagnosis of BC, the goal is to achieve total pCR (tpCR). This means that there is no more evidence of cancer in tissue samples taken during tumor removal surgery. For HER2 positive cancer, it is essential to fight HER2 to limit its growing effect on the BC. HER2 is a protein present on some BCs that help them grow. 

Pertuzumab and trastuzumab are used in combination as “dual HER2 blockade” to attack HER2. They are applied as an additional treatment along with chemotherapy prior to removal surgery. The aim is to downstage BC and increase surgery success. Further classification of BC is whether the BC grows in response to female hormones like estrogen (HR-positive) or not (HR negative).

Previous studies have proven the effectiveness of the dual HER2 blockade as a successful treatment to achieve tpCR under the isolated environment of a clinical trial. However, in clinical trials patients are carefully selected and are usually young and without significant health problems. The safety and effectiveness of this drug combination in a real-world setting remain unknown. 

This study analyzed the data of 243 women with HER2 positive BC. All of them received pertuzumab and trastuzumab as a treatment in addition to either one taxane chemotherapy (CT) drug (11.1%), two CT drugs (taxanes and anthracyclines; 74.1%), or platinum-based CT (14.4%). All 243 received an average of four cycles of treatment and then underwent tumor removal surgery afterward.

The overall tpCR rate was 66.4%. Patients who received two CT drugs along with pertuzumab and trastuzumab had the highest rate of tpCR (71%). This rate was 59.3% for those who received one CT drug and 48.6% with platinum-based CT.

Patients who were HR-negative responded especially well with 80.9% tpCR compared to 55.4% for HR-positive BC. No treatment-related death was reported.

The study concluded that pertuzumab and trastuzumab are effective in achieving tpCR for patients with HER2 positive BC in daily clinical practice.

This study was based on medical records. The methods used to measure and judge tpCR were not strictly defined and varied within the study. This study was funded by Roche, the manufacturer of pertuzumab and trastuzumab.