Efficacy and Safety of Pegfilgrastim in Patients With Severe Congenital Neutropenia.

Background: Severe congenital neutropenia (SCN) is commonly treated with granulocyte colony-stimulating factor (G-CSF) to reduce neutropenia and the associated risk of infections. Pegfilgrastim, a long-acting form of G-CSF, provides the benefit of less frequent dosing; however, its application in SCN has not been extensively studied. This study aims to assess the long-term safety and effectiveness of transitioning SCN patients from standard G-CSF therapy to pegfilgrastim. Methods: We followed eight patients with severe congenital neutropenia (five males, average age 17.8 years) who had been on G-CSF treatment for at least five years. They were switched to pegfilgrastim injections (3-6 mg every 7-14 days). Dosing was individualized to obtain an absolute neutrophil count (ANC) above 1000/µL in all patients. Over a five-year follow-up under treatment with pegfilgrastim, patients were evaluated for ANC levels, infection frequency, adverse effects, and quality of life using the Functional Assessment of Cancer Therapy-Neutropenia (FACT-N) questionnaire. In addition, yearly abdominal ultrasounds, bone density every two years, and genetic screening for RUNX1 and the G-CSF receptor mutations were performed. Results: Pegfilgrastim significantly improved ANC levels compared to prior G-CSF treatment ( Conclusion: Pegfilgrastim can be used as an alternative to daily G-CSF in SCN, providing stable ANC and QoL improvements with individualized dosing. Larger studies are warranted to evaluate its long-term safety and efficacy. Clinical trial registration: This trial is registered at https://irct.behdasht.gov.ir/ in Iranian Registry of Clinical Trials (IRCT) # IRCT20150125020786N3.