Study in Participants With Early-Stage or Locally Advanced Human Epidermal Growth Factor Receptor (HER) 2-Positive and Estrogen Receptor/Progesterone Receptor Negative Breast Cancer to Evaluate the Efficiency and Safety of Treatment With Trastuzumab Plus (+) QL1209/Pertuzumab + Docetaxel.

This is A multi-center, randomized, double-blind, parallel control，comparative clinical trial. The primary objective is to evaluate whether the clinical efficacy of QL1209 and pertuzumab are similar in patients with early-stage or locally advanced HER2-positive and estrogen receptor/progesterone receptor negative breast cancer. The secondary objective are to evaluate whether the clinical safety and immunogenicity of QL1209 and pertuzumab are similar in patients with early-stage or locally advanced HER2-positive and estrogen receptor/progesterone receptor negative breast cancer.