An Open-label Prospective Study to Evaluate the Efficacy and Safety of Pegfilgrastim in Triple-Negative Breast Cancer Patients Receiving AC Regimen Following Paclitaxel and Carboplatin as Neoadjuvant Therapy

This open-label, prospective, single-arm clinical study aims to evaluate the efficacy and safety of pegfilgrastim in preventing febrile neutropenia (FN) among patients with triple-negative breast cancer (TNBC) receiving anthracycline/cyclophosphamide (AC) chemotherapy following neoadjuvant paclitaxel/carboplatin therapy. In the Keynote-522 regimen, paclitaxel and carboplatin are administered prior to the AC phase, which may increase cumulative myelosuppression and subsequently elevate the risk of FN during AC. Despite this clinical concern, real-world evidence supporting the prophylactic use of pegfilgrastim in Korean patients undergoing this regimen remains insufficient.

A total of 40 adult TNBC patients will be enrolled. Pegfilgrastim 6 mg will be administered subcutaneously once per cycle on Day 2 of each AC cycle (Cycles 1-4), approximately 24 hours after chemotherapy completion. The primary objective is to assess the incidence of FN during the four AC cycles. Secondary objectives include hospitalization due to FN, incidence of Grade 4 neutropenia, delays or dose reductions in chemotherapy due to neutropenia, and evaluation of hematologic and non-hematologic toxicities.

This study is descriptive in nature and does not involve hypothesis-testing sample size calculations. The sample size of 40 was determined based on feasible drug supply and is expected to provide clinically meaningful insight when compared with existing real-world data, in which the FN risk during AC without prophylactic G-CSF is historically reported at approximately 20-25%. The findings from this study may offer essential clinical evidence supporting the preventive use of pegfilgrastim during the AC phase in TNBC patients treated with the paclitaxel/carboplatin-leading neoadjuvant regimen.

Study Overview

• Status: Recruiting
• Conditions: Triple-Negative Breast Cancer
• Intervention / Treatment: Drug: Pegfilgrastim (Neulasta)

• Study Type: Interventional
• Enrollment (Estimated): 40
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Gun Min Kim, Professor; Phone Number: 02-2228-8126; Email: gmkim77@yuhs.ac

Study Locations

• South Korea
  • Seoul, South Korea, 06273
    • Recruiting
    • Gangnam Severance Hospital, Yonsei University Health System
    • Contact: Jee Hung KIM; Phone Number: +82 02-2019-3305; Email: OK8504@yuhs.ac
  • Seodaemun-gu
    • Seoul, Seodaemun-gu, South Korea, 03722
      • Recruiting
      • Severance Hospital, Yonsei University Health System
      • Contact: Gun Min Kim; Phone Number: 02-2228-8126; Email: gmkim77@yuhs.ac

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• 1. Women diagnosed with triple-negative breast cancer by pathology or cytology. 2. Age ≥19 and ≤70 years. 3. ECOG performance status 0-1. 4. Stage II-III breast cancer confirmed pathologically or clinically. 5. Planned to receive AC chemotherapy following paclitaxel/carboplatin as neoadjuvant therapy.

  6. Adequate organ function:

  1. Absolute neutrophil count (ANC) ≥1,000 cells/mm³
  2. Platelet count ≥75,000 cells/mm³
  3. Creatinine clearance ≥50 mL/min or serum creatinine <1.5× ULN
  4. Total bilirubin ≤1.5× ULN
  5. AST ≤2.5× ULN

  6. ALT ≤2.5× ULN 7. Ability to provide written informed consent and willingness to comply with study procedures.

     Exclusion Criteria:

• 1. Prior treatment with cytotoxic chemotherapy. 2. Prior treatment with G-CSF or pegylated G-CSF. 3. History of conditions that may affect bone marrow function (e.g., severe liver or kidney disease).

  4. Receipt of radiotherapy within 4 weeks prior to study initiation. 5. Active uncontrolled infection or inflammatory disease that may affect study outcomes.

  6. Receipt of blood transfusion within 60 days prior to study initiation. 7. Pregnant, breastfeeding, or unwilling to use appropriate contraception. 8. Any condition judged by the investigator to make the patient unsuitable for participation.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Pegfilgrastim During AC Chemotherapy; Participants receive pegfilgrastim 6 mg subcutaneously once per cycle on Day 2 during four cycles of AC chemotherapy (doxorubicin/cyclophosphamide).	Drug: Pegfilgrastim (Neulasta); Pegfilgrastim 6 mg is administered subcutaneously once per cycle on Day 2 (approximately 24 ± 2 hours after completion of AC chemotherapy) for a total of four cycles (Cycle 1-4).

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence of Febrile Neutropenia (FN)	Incidence of febrile neutropenia defined as (1) fever ≥38.3°C once or ≥38.0°C twice within 24 hours AND (2) ANC <500/mm³ or ANC <1,000/mm³ with a decline to <500/mm³ within 48 hours.	Up to 12 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Hospitalization rate due to febrile neutropenia	Proportion of participants requiring hospitalization due to febrile neutropenia.	Up to 12 weeks
Incidence of Grade 4 Neutropenia	Incidence of Grade 4 neutropenia assessed by laboratory values at each chemotherapy cycle.	Up to 12 weeks
Chemotherapy Delay or Dose Reduction Due to Neutropenia	Proportion of participants experiencing AC dose delay or dose reduction due to neutropenia.	Up to 12 weeks
Safety: Hematologic and Non-hematologic Toxicities	Assessment of hematologic and non-hematologic adverse events based on NCI CTCAE v5.0.	Up to 6 months after completion of treatment

Collaborators and Investigators

• Sponsor: Yonsei University
• Investigators: Principal Investigator: Gun Min Kim, Professor, Severance Hospital

Study record dates

Study Major Dates

• Study Start (Actual): October 28, 2025
• Primary Completion (Estimated): October 27, 2026
• Study Completion (Estimated): October 27, 2026

Study Registration Dates

• First Submitted: March 22, 2026
• First Submitted That Met QC Criteria: April 6, 2026
• First Posted (Actual): April 13, 2026

Study Record Updates

• Last Update Posted (Actual): April 20, 2026
• Last Update Submitted That Met QC Criteria: April 14, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Neoplasms by Site; Neoplasms; Skin Diseases; Breast Diseases; Breast Neoplasms; Skin and Connective Tissue Diseases; Triple Negative Breast Neoplasms; pegfilgrastim
• Other Study ID Numbers: 4-2025-1181

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No