Acute Lymphoblastic Leukemia Patient with Variant ATF7IP/PDGFRB Fusion and Favorable Response to Tyrosine Kinase Inhibitor Treatment: A Case Report
Challenging differential diagnosis, Unusual or unexpected effect of treatment, Diagnostic / therapeutic accidents, Unexpected drug reaction , Rare disease, Educational Purpose (only if useful for a systematic review or synthesis)
Ge Zhang, Yanle Zhang, Jianrong Wu, Yan Chen, Zhigui Ma
Department of Pediatrics, Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Health, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, China (mainland)
Am J Case Rep 2017; 18:1204-1208
Chromosomal translocations involving the PDGFRB gene have been reported in a broad spectrum of hematological malignancies. An ATF7IP/PDGFRB fusion was recently identified in a Philadelphia chromosome-like (Ph-like) B-progenitor acute lymphoblastic leukemia (B-ALL) patient. Here we report on a special case of a Ph-like ALL patient who had a variant ATF7IP/PDGFRB fusion.
CASE REPORT: In this case, a variant fusion was created between ATF7IP exon 9 (instead of exon 13) and PDGFRB exon 11, resulting in the loss of 411 nucleotides and 137 amino acids in the ATF7IP/PDGFRB fusion cDNA and its encoded chimeric protein, respectively. Interestingly, ATF7IP has also been reported as a fusion partner of the JAK2 kinase gene in Ph-like ALL, but all of the genomic breakpoints in ATF7IP in this fusion reported thus far occurred in intron 13. Enforced expression of the variant ATF7IP/PDGFRB fusion induced cytokine-independent growth and glucocorticoid resistance of BaF3 cells. Similar to the initially described ATF7IP/PDGFRB-bearing Ph-like ALL patient who was refractory to conventional chemotherapy but highly sensitive to tyrosine kinase inhibitor (TKI) monotherapy, our patient with a variant ATF7IP/PDGFRB fusion had a poor initial treatment response to chemotherapy but responded well to TKI-based therapy and is now doing well in continuous remission.
CONCLUSIONS: Ph-like ALL patient with an ATF7IP/PDGFRB fusion is rare, but can benefit from TKI therapy.
Keywords: Oncogene Fusion, Philadelphia Chromosome, Precursor Cell Lymphoblastic Leukemia-Lymphoma