# A reduced-toxicity myeloablative conditioning approach for hematopoietic cell transplant in juvenile myelomonocytic leukemia

## TL;DR

A new reduced-toxicity treatment approach for juvenile myelomonocytic leukemia shows 100% survival and no transplant-related deaths in a small patient group.

## Contribution

A novel busulfan/melphalan-based conditioning regimen with no transplant-related mortality in JMML patients.

## Key findings

- 100% disease-free and overall survival observed in 17 JMML patients after HCT.
- Prompt immune reconstitution was achieved with the cyclophosphamide-sparing regimen.
- No transplant-related mortality was reported with the reduced-toxicity approach.

## Abstract

Allogeneic hematopoietic cell transplantation (HCT) is a potentially curative treatment for most children with juvenile myelomonocytic leukemia (JMML), but overall survival remains poor at 50%. Given its rarity and heterogeneity, there is no standard HCT conditioning regimen for JMML.

Retrospective study of consecutive patients with JMML who underwent HCT using a busulfan/ melphalan backbone conditioning regimen (n=17) at two academic centers.

The median age at HCT was 1.9 (range 0.7-6.0) years. At a median follow up of 7.6 (range 2.9-21.5) years, 100% disease-free (DFS) and overall survival (OS), with prompt immune reconstitution were observed. This cyclophosphamide-sparing approach was associated with no transplant related mortality.

Given excellent clinical outcomes at extended follow-up, prospective studies are needed to confirm our findings in this ultra-rare disease.