Spontaneous remission of chronic myeloid leukaemia with loss of the Philadelphia chromosome

Spontaneous Remission in a Patient with Chronic Myeloid Leukemia: A Case Report

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm in which granulocytic cells are the main proliferative component. At diagnosis, more than 90% of CML cases have the characteristic Philadelphia chromosome, containing the BCR::ABL1 fusion gene. The natural history of untreated CML is an initial indolent chronic phase which will be followed by an accelerated phase, blast phase, or both. Tyrosine kinase inhibitors (TKIs) have dramatically altered the natural history of CML. TKI discontinuation with the goal of treatment-free remission is currently part of current management recommendations. However, spontaneous remission without receiving any treatment is extraordinarily rare in CML patients. Herein, we report a 56-year-old male who presented with leukocytosis and was diagnosed as a case of CML in the chronic phase; however, treatment with TKIs was not initiated due to spontaneous hematological as well as molecular remission.

Direct evidence that leukemic cells present HLA-associated immunogenic peptides derived from the BCR-ABL b3a2 fusion protein

The BCR-ABL oncogene is central in the pathogenesis of chronic myeloid leukemia (CML). Here, tandem nanospray mass spectrometry was used to demonstrate cell surface HLA-associated expression of the BCR-ABL peptide KQSSKALQR on class I-negative CML cells transfected with HLA-A*0301, and on primary CML cells from HLA-A3-positive patients. These patients mounted a cytotoxic T-lymphocyte response to KQSSKALQR that also killed autologous CML cells, and tetramer staining demonstrated the presence of circulating KQSSKALQR-specific T cells. The findings are the first demonstration that CML cells express HLA-associated leukemia-specific immunogenic peptides and provide a sound basis for immunization studies against BCR-ABL.

BCR-ABL fusion peptides and cytotoxic T cells in chronic myeloid leukaemia

The BCR-ABL gene that arises in chronic myeloid leukaemia (CML) is a neoantigen. Peptides derived from the BCR-ABL fusion junction may therefore be immunogenic, if appropriately presented to the immune system. This article reviews data demonstrating that certain junctional peptides will bind to HLA molecules, and that these peptides will elicit specific T-lymphocyte responses in vitro, in both normal subjects and in CML patients. The clinical relevance of these observations is discussed.