CD19-directed treatment in B-cell precursor acute lymphoblastic leukaemia (BCP-ALL) frequently leads to the downmodulation of targeted antigens. As multicolour flow cytometry (MFC) application for minimal/measurable residual disease (MRD) assessment in BCP-ALL is based on B-cell compartment study, CD19 loss could hamper MFC-MRD monitoring after blinatumomab or chimeric antigen receptor T-cell (CAR-T) therapy. The use of other antigens (CD22, CD10, CD79a, etc.) as B-lineage gating markers allows the identification of CD19-negative leukaemia, but it could also lead to misidentification of normal very-early CD19-negative BCPs as tumour blasts. In the current study, we summarized the results of the investigation of CD19-negative normal BCPs in 106 children with BCP-ALL who underwent CD19 targeting (blinatumomab, n = 64; CAR-T, n = 25; or both, n = 17). It was found that normal CD19-negative BCPs could be found in bone marrow after CD19-directed treatment more frequently than in healthy donors and children with BCP-ALL during chemotherapy or after stem cell transplantation. Analysis of the antigen expression profile revealed that normal CD19-negative BCPs could be mixed up with residual leukaemic blasts, even in bioinformatic analyses of MFC data. The results of our study should help to investigate MFC-MRD more accurately in patients who have undergone CD19-targeted therapy, even in cases with normal CD19-negative BCP expansion.
Immunocompromised patients, including HSCT recipients, may have a poor prognosis after contracting COVID-19 due to the absence of a pathogen-specific adaptive immune response. One of the possible options for severe COVID-19 treatment may be the transfusion of hyperimmune SARS-CoV-2 convalescent plasma.
A 9-month-old girl with juvenile myelomonocytic leukemia received an HSCT from a haploidentical donor. On day +99, during routine virologic monitoring, SARS-CoV-2 was detected without any clinical symptoms. On day +144, the child developed a polysegmental bilateral viral pneumonia with 60 % damage to the lung tissue and confirm a positive SARS-Cov-2 results in throat swab. The patient was treated with tocilizumab and three doses of fresh frozen plasma obtained from a SARS-CoV-2 convalescent patient.
Therapy with tocilizumab and three doses of fresh frozen plasma was well tolerated. In spite of full resolution of the lung lesions, complete elimination of SARS-CoV-2 has not been achieved 4 months after the first detection, which is due to persistence of secondary immunodeficiency after HSCT and the lack of reconstitution of the adaptive immune response.
This case represents a demonstration of an atypical course of COVID-19 and the delayed development of lung lesions, which was most likely associated with the features of the patient's immune status after HSCT. SARS-CoV-2 convalescent plasma in combination with other therapeutic approaches is one of the possible curative options for this clinical situation.
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