Non-hematopoietic stem cell transplantation treatment of juvenile myelomonocytic leukemia: a retrospective analysis and definition of response criteria.
BACKGROUND
Juvenile myelomonocytic leukemia (JMML) is a rare myeloproliferative disease of infancy. Allogeneic hematopoietic stem cell transplantation (HSCT) is currently the only curative treatment modality, while the role of anti-leukemic therapy prior to HSCT is uncertain. A comparative evaluation of the efficacy of different clinical protocols and great variety of anti-neoplastic drugs applied pre-HSCT is hampered by the lack of uniform criteria of response. Classification schemas applied in other forms of leukemia are of little value, because in JMML therapy may result in divergent responses in solid organs compared to peripheral blood (PB).


METHODS
We therefore defined separate response criteria for white blood count (WBC), platelet count, liver size, and spleen size. We then retrospectively evaluated the efficacy of 129 treatment courses other than HSCT administered to 63 children with JMML. Treatment consisted of intensive therapy according to AML-type chemotherapy, maintenance-type combination therapy, and single agent therapy. To account for the variability observed in the natural course of disease, we also evaluated 32 episodes of "no therapy."


RESULTS
Best responses within 3 months of initiation of therapy were highly variable for the four response criteria. In contrast to platelet count and liver size, there was a significant correlation between WBC or spleen size and therapy. Response rates for WBC and spleen size were best for purine analogs, etoposide, and cytarabine as single agents or for maintenance-type combination therapy.


CONCLUSIONS
To rigorously test future therapeutic strategies in this rare disease an international consensus on the definition of response criteria will be helpful.
Bergstraesser
Eva
E
Division of Pediatric Hematology and Oncology, University Children's Hospital Zürich, Zürich, Switzerland.
Hasle
Henrik
H
Rogge
Tim
T
Fischer
Alexandra
A
Zimmermann
Martin
M
Noellke
Peter
P
Niemeyer
Charlotte M
CM
D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001773:Blood Cells / Q000187:drug effects; D004341:Drug Evaluation; D006801:Humans; D015477:Leukemia, Myelomonocytic, Chronic / Q000188:drug therapy / Q000628:therapy*; D007958:Leukocyte Count; D008099:Liver; D009929:Organ Size / Q000187:drug effects; D010976:Platelet Count; D012189:Retrospective Studies; D013154:Spleen; D016896:Treatment Outcome
D000970:Antineoplastic Agents