PMC6917542_01
Y253H and T315I mutation in the ABL1 kinase domain were detected by PCR-direct sequencing before and after anti-CD19 CAR-T treatment. (A) Y253H mutation in the ABL1 kinase domain was identified in the patient after imatinib treatment for half a year. (B) T315I mutation was identified about half a year after switching from imatinib to dasatinib, while Y253H was undetectable. (C) No mutations were identified after chemotherapy followed by anti-CD19 CAR-T therapy. Colors green, red, black and blue represent nucleobases of A, T, G and C, respectively.
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ABL1 kinase domain (Figure 1). As a result, dasatinib (100mg/d) was given instead. T315I mutation was identified in Sanger sequencing (Figure 1). The patient was then given induction chemotherapy with the daunorubicin, L-asparaginase, prednisone, and cyclophosphamide (DVCLP) regimen in combination with dasatinib (100mg/d) for two courses of treatment on March 5 and April 23, 2018, respectively. Moreover, Sanger sequencing on August 14, 2019 detected no BCR-ABL1 kinase mutation in the patient (Figure 1).
BCR-ABL1 expression level, leukocyte number and the percentage of blast cells in bone marrow before and after anti-CD19 CAR-T treatment since April 24, 2017.
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It was shown that the BCR-ABL1 level decreased from 50.76% (IS) to 4.12% (IS) after chemotherapy in combination with dasatinib, then increased to 10.82% (IS) 3 months later (Figure 2). By August 27, 2019, the BCR-ABL1 level was still at the level of 0 (Figure 2).
Patient responses after infusion. (A) After infusion, the number of CAR copies in the peripheral blood continued to increase and reached the highest value on day 10. The number of CAR copies remained high even after administration 320 mg tocilizumab. No CAR copies were detected 120 days after infusion. (B) Serum cytokine levels increased after anti-CD19 CAR-T cell infusion.
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No immediate infusion-related toxicity was observed, but he developed rigor and fever (38 C) by day +10, with C-reactive protein (CRP 2.65 mg/L), cytokine levels (Figure 3), and ferritin (960 ng/mL) increasing significantly. Within 60 days after the infusion of CAR-T cells, no visceral toxicity and no cytokine release syndrome (CRS) above 3 degrees (NCI-CTCAE standard) were observed (Figure 3).