PMC9827176_01
Positron emission tomography/computerized tomography scan and bone marrow examination before and afer chimeric antigen receptor T-cell infusion. (A and B) Positron emission tomography/computerized tomography (FDG-PET/CT) scan coronal maximum intensity projection (MIP) images before leukapheresis with avid uptake of abdominal lymph nodes (A) and 3 months after CD19-directed chimeric antigen receptor (CAR) T-cell therapy (B), showing metabolic complete response of diffuse large B-cell lymphoma (DLBCL). (C) Bone marrow (BM) biopsy taken before CAR T-cell infusion showing an hypocellular marrow without leukemic infiltration (hematoxylin and eosin staining; magnification x400). (D) The same sample as (C) showing only rare CD34+ cells within the normal range (red arrow); vessel endothelial cells serve as positive control (black arrow) (immunoperoxidase, diaminobenzidine; magnification x200). (E) BM biopsy taken 2 months after CAR T-cell infusion showing hypocellular marrow infiltrated by CD34+ leukemic cells (red arrows); vessel endothelial cells serve as positive control (black arrows) (immunoperoxi-dase, diaminobenzidine; magnification x200). (F) BM smear 2 months after CAR T-cell infusion showing myeloid blasts exhibiting erythrophagocytosis (black arrows) (May-Grunwald-Giemsa staining, magnification x400).
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In March 2021, PET/CT showed again disease progression (Figure 1A). In August 2021, the BCC was: WBC 4.310/mm (neuthrophils 56%), Hb 10.6 g/dL, platelets 80.000/mm and the BM biopsy showed hypocellular marrow without clear MDS or neoplastic infiltrates (Figure 1C) with a normal percentage of CD34+ cells (Figure 1D). PET/CT scan performed at 1 and 3 months after CAR T cells showed CR (Figure 1B). Due to persistent severe pancytopenia resulting from lymphodepleting therapy (WBC 450/mm, Hb 8 g/dL, platelets 6.000/mm on 27/10/21) lasting 60 days after CAR T-cell infusion and requiring transfusion support, a new BM biopsy and aspirate was performed that showed hypocellular marrow infiltrated by 40-50% blast cells with myelomonocytic appearance expressing CD34 (Figure 1E), myeloperoxidase and CD68, and frequently exhibiting erythrophagocytosis (Figure 1F).
Clonal evolution from clonal hematopoiesis to therapy related acute myeloid leukemia. The fish plot shows the inferred clonal evolution pattern based on targeted sequencing. The phylogenetic trees visualize the estimated order of mutation acquisition and the proportion of subclones with a different combination of mutations at each time point. The PPM1D mutation has been depicted as presumptively subclonal within the DNMT3A-mutant preleukemic clone, but its low variant allele frequency (VAF) would be compatible also with the existence of a separate PPM1D-mutant chromatin immunoprecipitation clone independent from (i.e., outside of) the DNMT3A-mutant preleukemic clone. RUNX1 missense mutation has been presumptuously depicted as subclonal within the RUNX1 splice site mutant leukemic clone. R-BENDA: rituximab, bendamustine; R-CMP: rituximab, cyclofosfamide, non-pegylated liposomal doxorubicin, prednisone; R-DHAOX: rituximab, high dose ARAc, oxaliplatin; ASCT, preceded by fotemustine, etoposide, ARAc and melphalan; R-lenalidomide: rituximab-lenalidomide; HAM: high dose ARA-C and mitoxantrone; TLI: total lymphonodal irradiation.
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Targeted sequencing of stored DNA from the BM samples taken before CAR T-cell therapy showed the presence of the PPM1D mutation but not RUNX1 mutations (Figure 2).