Prolonged infective SARS-CoV-2 omicron variant shedding in a patient with diffuse large B cell lymphoma successfully cleared after three courses of remdesivir.

We report a case of prolonged shedding of the infective SARS-CoV-2 omicron variant BA.1.1.2 in a 79-year-old male patient with diffuse large B-cell lymphoma, after receiving chemotherapy with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP). The patient was admitted to our hospital in late March 2022 for the sixth course of R-CHOP chemotherapy. Initially, the patient tested negative for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using an in-hospital loop-mediated amplification assay with a nasopharyngeal swab, both on the day of admission and three days later. However, the patient developed fever and was diagnosed with coronavirus disease (COVID-19) six days after admission and was suspected to have contracted the infection in the ward. Viral shedding continued for more than three months, with confirmed viral infectivity. As compared to the original Wuhan-Hu-1/2019 strain, amino acid substitutions including S36 N in non-structural protein (NSP)2, S148P, S1265del and L1266I in NSP3, G105D in NSP4, G496S, A831V, or V987F in spike protein, and I45T in open-reading frame (ORF)9b were randomly detected in isolated viruses. Although the patient had received two doses of the BNT162b2 vaccine approximately six months earlier and the third dose on day 127 after the infection, both serum anti-spike and anti-nuclear protein IgG and IgM tests were negative at day 92, 114, and 149 after the infection. The patient finally cleared the virus after the third course of remdesivir and did not have further recurrence.

Pharmacokinetics of dasatinib in a hemodialysis patient with chronic myeloid leukemia and chronic kidney disease.

Until now, no studies have addressed the use of dasatinib in hemodialysis patients. Herein, we report the case of a 73-year-old hemodialysis patient with chronic myeloid leukemia (CML) who was treated with dasatinib. For 5 years prior, the patient had received nilotinib for the treatment of CML. Regular hemodialysis was initiated due to progression of hypertensive nephrosclerosis, whereupon nilotinib was discontinued and the patient began receiving 100 mg dose of dasatinib once daily. On dialysis days, dasatinib was administered immediately after completion of dialysis. Four months after starting dasatinib, we performed a pharmacokinetic study. The plasma concentrations of dasatinib before, immediately, and 2 h after the completion of hemodialysis were 7.4, 6.1, and 59.5 ng/mL, respectively. Ultrasound cardiography revealed a gradual decline in ejection fraction during dasatinib therapy. Because the patient's dasatinib trough concentration was higher (6.1 ng/mL) than the target level (1.5 ng/mL), we suspected the development of dasatinib-related heart dysfunction; thus, dasatinib was discontinued 6 months after its initiation. We concluded that hemodialysis patients are potentially vulnerable to the cardiotoxic effects of dasatinib; monitoring of cardiac function and plasma drug concentration may thus be useful in assessing their condition.

Analysis of changes in CD20, CD55, and CD59 expression on established rituximab-resistant B-lymphoma cell lines.

Rituximab has markedly improved treatment results for B-cell lymphoma, but there are resistance problems similar to those of other chemotherapy drugs. With regard to the acquisition of rituximab resistance, there have been several reports describing the relation between rituximab and complement regulatory factors or CD20, but many points remain unclear. To further investigate acquisition of resistance to rituximab-related complement-dependent cytotoxicity (CDC), we established rituximab-resistant B-lymphoma cell lines (RAMOS) in vitro and then analyzed expression of CD20, CD55, and CD59 on these resistant cells by flow cytometry. With repeated exposure to a low concentration of rituximab and complement, RAMOS cells gradually acquired rituximab resistance, and selection and increase of CD55(bright) and CD59(bright) cell populations due to rituximab-related CDC were observed. With repeated exposure to a high concentration of rituximab and complement, RAMOS cells promptly acquired rituximab resistance, and CD20 expression of RAMOS cells was decreased. Not only selection of CD20(dim) cells but also down-modulation of CD20 caused by rituximab-related CDC appeared to cause the decrease in CD20 expression. We believe our findings will prove to be useful for prevention of or release from rituximab resistance in cases of B-cell lymphoma.

[CD25 positive chronic eosinophilic leukemia with myelofibrosis].

A 70-year-old man was referred to our hospital in March 2001 for the purpose of evaluation for anemia and thrombocytopenia. Physical examination revealed hepatosplenomegaly, normal skin, and normal neurologic findings. Blood examination showed a white blood cell count of 10,900/microliter, with a differential count of 58.5% eosinophils and 3.5% blast cells. Flow cytometric analysis of eosinophils revealed that they were positive for CD33, CD13, CD25, and HLA-DR. Bone marrow aspiration could not be performed due to dry tap, and bone marrow core biopsy specimen revealed severe myelofibrosis with blastoid cells proliferation. Cytogenetic analysis of bone marrow cells showed isochromosome 17. FISH analysis using a RAR alpha probe (17q21.1) demonstrated 62% of peripheral blood nucleated cells having three signals. BCR/ABL gene rearrangement by FISH analysis was not observed. Allergic disease, infectious disease, parasitic disease, collagen vascular diseases, pulmonary disease, and neoplastic disorders were excluded. Therefore, a diagnosis of chronic eosinophilic leukemia was made. The patient had no symptoms of hypereosinophilia. However, eosinophils with sparse granulation, positivity for CD25, elevated serum levels of soluble IL-2 receptor, and elevated serum levels of eosinophil cationic protein suggested activation of eosinophils. Further analysis is needed regarding the activation of eosinophils in chronic eosinophilic leukemia.