Telpegfilgrastim vs Filgrastim for Secondary Prevention of Chemotherapy-Induced Neutropenia in Pediatric Solid Tumors

This multicenter, randomized, open-label, controlled clinical trial evaluates the efficacy and safety of Telpegfilgrastim, a novel 40kD Y-branched PEGylated recombinant human granulocyte colony-stimulating factor (PEG-rhG-CSF), compared to Filgrastim (short-acting rhG-CSF) in preventing chemotherapy-induced neutropenia (CIN) among pediatric and adolescent patients (aged 6-24 years) with malignant solid tumors receiving high-intensity chemotherapy. The study employs a two-phase adaptive design: Phase 1 involves 20 participants (15 in the Telpegfilgrastim arm, 5 in the Filgrastim arm) to assess preliminary pharmacokinetics (PK) and safety, including drug half-life (71.7 ± 23 hours for Telpegfilgrastim vs. 3.5-4 hours for Filgrastim) and neutrophil recovery dynamics, with potential dose adjustments before progressing to Phase 2. The full trial enrolls 132 participants randomized 3:1 (99 vs. 33), stratified by age subgroups (6-12, 13-18, 19-24 years) to account for developmental variations in drug metabolism. Telpegfilgrastim is administered as a single subcutaneous injection (33 μg/kg, max 2 mg) 24 hours post-chemotherapy, leveraging its prolonged activity from Y-shaped PEGylation, while Filgrastim requires daily injections (5 μg/kg/day) until absolute neutrophil count (ANC) recovers to ≥10.0×10⁹/L. Concomitant use of other myelostimulatory agents (e.g., GM-CSF, trilaciclib) is prohibited to isolate treatment effects.

Neutrophil monitoring includes ANC measurements at baseline and days 7, 9, 11, 13, 15, and 21 (±1 day) post-chemotherapy using standardized hematology analyzers. Febrile neutropenia (FN) is strictly defined as ANC <0.5×10⁹/L (Grade 4) or ANC 0.5-<1.0×10⁹/L (Grade 3) with anticipated decline to <0.5×10⁹/L within 48 hours, accompanied by axillary temperature ≥37.7°C sustained for ≥1 hour. Bone pain, a key safety focus, is assessed using age-specific tools: the FLACC scale (Face, Legs, Activity, Cry, Consolability; 0-10) for children <8 years and the Wong-Baker Faces Pain Rating Scale (0-10) for older participants. Exploratory analyses evaluate bone metabolism through serial serum osteocalcin (osteoblast activity marker) and RANKL/OPG ratio (osteoclast regulation) measurements at baseline, day 7, and day 21, with optional bone marrow aspirates to assess hematopoietic stem/progenitor cell (HSPC) mobilization efficiency.

Data management utilizes a validated electronic data capture (EDC) system with real-time entry and automated queries for anomalies, complemented by source data verification (SDV) for ≥20% of cases, prioritizing primary endpoints and serious adverse events (SAEs). Sample size (132 participants) is calculated based on prior pediatric FN incidence rates (45% PEG-rhG-CSF vs. 75% rhG-CSF), with α=0.05, 80% power, and 20% attrition. Statistical analyses employ the Full Analysis Set (FAS, intent-to-treat) and Per-Protocol Set (PPS), using ANOVA or nonparametric tests for continuous variables (e.g., ANC recovery time) and Chi-square/Fisher's exact tests for categorical outcomes (e.g., FN incidence), adjusted for age, tumor type, and chemotherapy regimen. Safety analyses include all participants receiving ≥1 dose (Safety Set), with SAEs reported per ICH-GCP and China NMPA guidelines, monitored by an independent Data Safety Monitoring Board (DSMB).

Ethical compliance is ensured through institutional review board (IRB) approvals at all 16 participating centers, emphasizing informed consent/assent for adolescents, anonymized biological sample storage (≤5 years post-trial), and voluntary withdrawal rights. The trial's innovation lies in its focus on pediatric PK/PD profiling, addressing faster drug clearance in children, and evaluating long-term skeletal safety via bone metabolism biomarkers-critical for growing populations. By comparing next-generation PEG-rhG-CSF with conventional rhG-CSF, this study aims to refine global supportive care guidelines for pediatric oncology, balancing efficacy and safety in high-intensity chemotherapy settings.