Compare the Efficacy and Safety of QL0605 Injections at Different Timepoints

This study is comparing two different timing schedules for giving QL0605 — a long-acting version of a white blood cell booster (a PEGylated G-CSF injection) — to help prevent dangerously low white blood cell counts in breast cancer patients receiving chemotherapy. The goal is to find the best time to give the injection to reduce infection risk. **You may be eligible if...** - You are 18 or older - You have invasive breast cancer confirmed by biopsy - You are planning to receive TAC, TC, or TCbH chemotherapy - Your blood counts and organ function are in good shape - Your life expectancy is more than 3 months - You are in reasonable overall health (ECOG score ≤ 2) **You may NOT be eligible if...** - You are pregnant or breastfeeding - You have had chemotherapy or radiation within the last 4 weeks - You received a PEG-rhG-CSF injection within the last 6 weeks - You have an uncontrolled infection - You have a known allergy to G-CSF or PEG-G-CSF - You have another untreated cancer Talk to your doctor to see if this trial is right for you.