Correlation Between ANC and Bone Pain in Breast Cancer Patients Receiving Long-Acting G-CSF

A Prospective, Multicenter, Non-Randomized Controlled Study on the Correlation Between Absolute Neutrophil Count (ANC) and Bone Pain During the Prevention of Chemotherapy-Induced Neutropenia and Febrile Neutropenia (CIN/FN) With Long-Acting G-CSF in Breast Cancer Patients Receiving Intermediate- to High-Risk Chemotherapy

This prospective, multicenter, non-randomized controlled study aims to evaluate bone pain associated with prophylactic use of long-acting granulocyte colony-stimulating factors (G-CSFs) in patients with breast cancer receiving chemotherapy with a moderate-to-high risk of febrile neutropenia (FN).

A total of 132 patients with breast cancer receiving neoadjuvant or adjuvant chemotherapy will be enrolled at 7 study centers in China. According to the long-acting G-CSF selected by the treating physician in routine clinical practice, patients will be included in either the Telpegfilgrastim group or the non-Telpegfilgrastim group. Telpegfilgrastim is administered as a fixed 2 mg subcutaneous dose 24 hours after chemotherapy. Patients in the non-Telpegfilgrastim group receive another approved long-acting G-CSF according to the physician's clinical decision.

The study will assess the incidence and duration of bone pain during the first chemotherapy cycle as the primary outcome. Bone pain during subsequent chemotherapy cycles, use of treatment for bone pain, and dose reduction or switching of long-acting G-CSF will also be evaluated. Absolute neutrophil count (ANC) and other laboratory parameters will be monitored during treatment to explore the relationship between neutrophil changes and bone pain.

Inclusion Criteria:

1. Histologically or cytologically confirmed breast cancer.
2. Patients considered by the investigator to be suitable for neoadjuvant or adjuvant chemotherapy with an anthracycline- and/or taxane-containing regimen administered in 21-day cycles, and expected to receive at least 3 chemotherapy cycles.
3. Age ≥18 years and <70 years.
4. Body weight ≥45 kg.
5. Eastern Cooperative Oncology Group (ECOG) performance status ≤2.
6. Adequate baseline white blood cell and neutrophil counts before chemotherapy: white blood cell count (WBC) ≥3.5 × 10^9/L and absolute neutrophil count (ANC) ≥1.5 × 10^9/L.
7. Expected survival ≥3 months.
8. Willing to participate in the study, able to understand the study procedures, and able to provide written informed consent.

Exclusion Criteria:

1. Previous or anticipated large-field radiotherapy involving >25% of the total bone marrow.
2. Significant dysfunction of major organs, including heart, lung, liver, or kidney; liver function abnormalities defined as ALT or total bilirubin >2.5 × ULN, or >5 × ULN in patients with liver metastases; hepatitis B virus infection, hepatitis C virus infection, or cirrhosis; or serum creatinine >1.5 × ULN.
3. Pregnant or breastfeeding women.
4. Previous or ongoing bone marrow transplantation or organ transplantation.
5. Known hypersensitivity to G-CSF or any component of a G-CSF product.
6. Patients who are unable to reliably understand or report their medical condition.
7. Any other condition that, in the investigator's judgment, makes the patient unsuitable for participation in the study.