The Colony-Stimulating Factor 3 Receptor M696T Mutated in a Patient with Ph+ Acute Lymphoblastic Leukemia

Purpose: Colony-stimulating factor 3 receptor (CSF3R) mutations have been identified in a variety of myeloid disorders, such as severe congenital neutropenia (SCN), chronic neutrophilic leukemia (CNL), myelodysplastic syndrome (MDS), acute myeloid leukemia (AML), and atypical chronic myelogenous leukemia (aCML). Although CSF3R point mutations (e.g., T618I) are emerging as key players in CNL/aCML, the significance of rarer CSF3R mutations is unknown. We report a case of philadelphia chromosome positive acute lymphoblastic leukemia (Ph+ ALL) with the M696T mutation in CSF3R gene and assess the pathogenicity of the CSF3R M696T mutation in Ph+ ALL.

Experimental Design: Here we report on a 32-year-old female who presented with asthenia. The initial hematological workup revealed white blood cell (WBC) count of 97 x 109/L (normal range 4-10 x 109/L). There was 84% prolymphocyte in the bone marrow. The immunophenotype of the blasts as judged from flow cytometry was in accordance with a B-ALL. The fusion gene for BCR-ABL P210 was positive. Hot mutation closely related to diseases was: CSF3R (nucleotide change c.2087 T>C, amino acid change p.M696T, mutation frequency 50.4%). Cytogenetic analysis showed 46, XX, t (9;22) (q34;q11). The patient was diagnosed as Ph+ ALL with the CSF3R M696T mutation and achieved Long-term survival after unrelated donor hematopoietic stem cell transplantation. Meanwhile we performed a series of experiments using murine interleukin 3 (IL-3)-dependent Ba/F3 cell line to evaluate the transforming capacity of the CSF3R M696T mutation. The phosphorylation of STAT3 was analyzed by G-CSF dependence assays and immunoblot analysis to evaluate the CSF3R M696T mutation contribution to the tumor transformation ability of Ba/F3 cells.

Results: This patient achieved complete remission with chemotherapy in combination with tyrosine kinase inhibitor (TKI) and long-term survival by unrelated donor transplantation. We confirmed the presence of a CSF3R M696T germline mutation in this patient, and the mutation was inherited from her mother. The experiments in vitro result showed the CSF3R M696T mutation harbors marginal contribution to the tumor transformation ability of Ba/F3 cells. CSF3R M696T mutation was neutral in tumor transformation ability.

Conclusions: We believe that TKI is still effective in patients with the CSF3R M696T mutation in Ph+ ALL. Donor with CSF3R M696T mutation might still be selected.