# Cyclophosphamide post-haploidentical stem cell transplantation experience in an infant with IPEX syndrome

## TL;DR

A male infant with IPEX syndrome received a successful stem cell transplant using a haploidentical donor and cyclophosphamide, leading to recovery.

## Contribution

Demonstrates the viability of haploidentical stem cell transplantation with cyclophosphamide for IPEX syndrome in the absence of an HLA-identical donor.

## Key findings

- The patient fully recovered nutritional status and immunity 320 days post-transplant.
- Haploidentical transplantation with cyclophosphamide showed promising outcomes for IPEX syndrome.
- The case contributes to evidence supporting this treatment for inborn errors of immunity.

## Abstract

IPEX syndrome is a rare hemizygous X-linked disorder with complex autoimmune reactions, characterized by immune dysregulation, polyendocrinopathy, and enteropathy. It has a poor prognosis and a high mortality risk without prompt therapy. Treatment options include pharmacological immunosuppression, nutritional and supportive care, and hematopoietic stem cell transplantation, the latter as the only curative option.

We present the case of a male infant, the second child of a non-consanguineous couple, with negative prenatal screening and intrauterine growth restriction detected at 27 weeks' gestation. He was diagnosed with neonatal diabetes mellitus and treated with insulin. He was re-hospitalized for secretory diarrhea and rotavirus infection. At that moment, he was diagnosed with failure to thrive and hypothyroidism. He acquired multiple severe infections, including Candida parapsilosis fungemia, an urinary infection caused by extended-spectrum ß-lactamase-producing Escherichia coli, and Klebsiella pneumoniae bacteremia. Endoscopy biopsy revealed chronic duodenitis with the absence of goblet and Paneth cells, findings suggestive of autoimmune enteropathy. Genetic testing identified a mutation in the FOXP3 gene, confirming the diagnosis of IPEX syndrome.

We performed a hematopoietic stem cell transplantation from an alternative haploidentical donor and administered a cyclophosphamide post-transplant regime. At 320 days post-transplant, the patient fully recovered his nutritional status and immunity.

Haploidentical transplantation with a post-transplant cyclophosphamide regime can be a viable therapeutic option for patients with IPEX syndrome, lacking an HLA-identical donor, with promising outcomes based on the follow-up data. Reporting these experiences with haploidentical hematopoietic stem cell transplantation in patients with inborn errors of immunity or other non-neoplastic diseases contribute to the growing body of evidence of this treatment.