In neoadjuvant trials, the incidence of LVEF decline with trastuzumab and docetaxel plus pertuzumab was what percentage compared to trastuzumab and docetaxel alone?

• A. 1.9%
• B. 4.2%
• C. 8.4%
• D. 12.7%

Answer: (C)

The main idea is how adding a second HER2-targeted antibody affects heart function during neoadjuvant therapy. In the neoadjuvant trial, including pertuzumab with trastuzumab and docetaxel increased the incidence of LVEF decline compared with trastuzumab and docetaxel alone. The difference was about 8.4 percentage points higher in the triple-therapy group. This reflects the added cardiotoxic risk of dual HER2 blockade, which is why cardiac monitoring is essential during treatment. The other options represent smaller or larger differences than what the trial reported, so 8.4% (points) is the figure the data support.