Relapse with BCR-ABL1 Elevation in Chronic Myeloid Leukemia after Progression to Multiple Myeloma from Monoclonal Gammopathy of Undetermined Significance with a Persistent KMT2D Mutation

Chronic myeloid leukemia (CML) and monoclonal gammopathy of undetermined significance (MGUS) are two different hematologic malignancies, the former arising from the myeloid cell lineage, and the latter arising from plasma cells. The concurrent diagnosis of CML and MGUS progression to multiple myeloma (MM) in one patient is an extremely rare event. A 59-year-old male was diagnosed with CML and MGUS with no discomfort in August 2012. Bone marrow (BM) aspiration suggested chronic myelogenous leukemia in chronic phase and perhaps myeloproliferative with 6.5% mature plasma cells (Figure 1A). FISH analysis detected that the BCR-ABL1 expression was 130%. And Next-generation sequencing (NGS) of BM showed: ASXL1 , KMT2D , SPEN , BRINP3 , ANKRD26 , PLCG1 , CUX1 were mutated (Figure 2I). The patient started oral imatinib 400 mg per day and achieved a complete cytogenetic response at 3 months. In September 2019, his IgG levels were 2,790 mg/dl (Figure 2J and serum immunofixation electrophoresis revealed monoclonal (M) protein of IgG-Lambda type (Figure 1E). BM aspiration revealed 9.5% plasma cell infiltration, including 6% mature plasma cells and 3.5% proplasmacyte (Figure 1C and 2H). Flow cytometry in BM showed 6.3% plasmacytoma and abnormal cell expressing CD38+CD138+CD56+CD117+clambda+ (Figure 1F). BM biopsy showed hematopoietic hyperplasia with abnormal growth of immature cells (Figure 1B). Fluorescent in situ hybridization (FISH) was negative. Mutations of KMT2D, SPEN, BRINP3, ANKRD26, PLCG1, CUX1, and ZMYM3 still existed(Figure 2I). In January 2020, examination of a new BM aspiration revealed that mature plasma cells were 3% and plasmablast and proplasmacyte were 4.5% (Figure 2H). In February 2020, he stopped IM therapy with undetectable BCR-ABL1 copies because he met the requirement of stopping TKI therapy . In March 2020, IgG levels were 3520 mg/dl and serum immunofixation electrophoresis still revealed monoclonal (M) protein of IgG-Lambda type. His BM aspiration demonstrated 13.5% plasma cells in April 2020 (Figure 2B and 2H). Flow cytometry in BM showed 6.44% (Figure 2F). BM biopsy showed extremely increased proliferation with abnormal growth of abnormal cells (Figure 2A). FISH demonstrated the presence of t(4;14)(p16;q32)(IGH/FGFR3) , 13q14 deletion（RB-1） and 13q14.3 （D13S319） (Figure 2C, 2D and 2E). The patient was diagnosed as MM (IgGλ type, D-S stage IA; ISS stage II) . BCR-ABL1 copies were still not detected at this point (Figure 2G). The patient continued his follow-up treatment of MM without chemotherapy.However, in June 2020, he was considered to have a molecular relapse with 0.2013% BCR-ABL1 copies in the peripheral blood (Figure 2G). NGS showed that the variant allele fractions of KMT2D, SPEN, BRINP3, ANKRD26, PLCG1, CUX1, and ZMYM3 mutations were similar to former . He restarted 400 mg daily IM therapy and BCR-ABL1 copies were undetectable againafter one month therapy (Figure 2G). BM aspiration revealed that the percentage of plasma cells increased to 25.5% in August 2020 (Figure 2H). Then the patient was started on treatment for ISS stage II standard risk myeloma with ID regimen: ixazomib 4 mg on days 1, 8 , 15 and dexamethasone 20 mg on days 1, 8, 15 , 22 in 28-day cycles. After 6 cycles , the patient got VGPR. BM aspiration demonstrated 13% plasma cells (Figure 2H). And he continued to receive myeloma treatment and imatinib . BCR-ABL1 were <MR4.5 (Figure 2G). Our research indicated that KMT2D mutation may make MGUS progress to MM with NK cells functional defects and then promote the recurrence of BCR-ABL1. Co-existence of these two diseases is rare, therefore, additional investigations are warranted. Acknowledgment:The research was supported by the Public Technology Application Research Program of Zhejiang, China (LGF21H080003), the Key Project of Jinhua Science and Technology Plan, China (2020XG-29 and 2020-3-011), the Academician Workstation of the Fourth Affiliated Hospital of the Zhejiang University School of Medicine (2019-2024), the Key Medical Discipline of Yiwu, China (Hematology, 2018-2020) and the Key Medical Discipline of Jinhua, China (Hematology, 2019-2021). Correspondence to: Dr Jian Huang, Department of Hematology, The Fourth Affiliated Hospital of Zhejiang University School of Medicine. N1 Shangcheng Road. Yiwu, Zhejiang, Peoples R China. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.