CRISPR/Cas9 gene editing clarifies the role of CD33 SNP rs12459419 in gemtuzumab ozogamicin-mediated cytotoxicity.

The single-nucleotide polymorphism (SNP) rs12459419 is located at the intron/exon junction of CD33 exon2. When exon2 is skipped by this CD33 SNP, the full-length CD33 (CD33FL) is converted to a short CD33 isoform (CD33D2). Since gemtuzumab ozogamicin (GO) only recognizes CD33FL, the CD33 SNP may affect the clinical efficacy of GO. To elucidate the significance of CD33 SNP on GO reactivity, we leveraged the CRISPR/Cas9 genome-editing system to create OCI-AML3 cell lines with specifically modified CD33 SNPs. Levels of CD33 D2 mRNA were significantly higher in the T/T clone (p < 0.001), but CD33D2 protein was not detectable in any clones. There was no significant difference in CD33FL mRNA expression across edited clones, and CD33FL protein expression was lowest in T/T clones, followed by T/C and C/C. Cytotoxicity assays revealed that the IC50 of GO was significantly lower in T/C and C/C clones than in the T/T clone (p < 0.001). Our study demonstrated a difference in GO-induced cytotoxicity in CD33 SNP-edited clones, clearly indicating that at least one CD33 SNP allele, rs12459419 C, is important for sensitivity to GO.

[Successful induction therapy for acute myeloid leukemia under management with extracorporeal membrane oxygenation].

A 53-year-old woman presented with shortness of breath and hyperleukocytosis and was admitted to our hospital. Shortly after, she went into cardiopulmonary arrest and was resuscitated. Her white blood cell count was 566,000/µl, with 94.5% cup-like blasts positive for MPO staining and FLT3-ITD positive, so she was diagnosed with acute myeloid leukemia (AML) M1. She also had disseminated intravascular coagulation and tumor lysis syndrome. Extracorporeal membrane oxygenation (ECMO) was started to manage bilateral pulmonary thromboembolism that had developed due to deep vein thrombosis, and induction therapy was performed under ECMO. On the third day of illness, the patient developed cerebral hemorrhage. Hematological remission was confirmed on the 39th day of illness. After consolidation therapy with chemotherapy and an FLT3 inhibitor, she underwent allogeneic hematopoietic stem cell transplantation, and remains alive. Case reports suggest strong evidence of mortality benefit from ECMO in patients with hematologic malignancies, particularly when ECMO served as a bridge through chemotherapy. Our patient suffered from cardiopulmonary arrest due to hyperleukocytosis and pulmonary thromboembolism, but was saved by induction of remission under ECMO. Improvements in supportive care should lead to reduction in early deaths during induction therapy.

[Successful immunosuppressive therapy in female hemophilia A developing inhibitor after perioperative administration of factor VIII products].

A 62-year-old woman was diagnosed as a hemophilia A carrier (factor VIII activity 35%) on preoperative examination of an ovarian tumor. A total of 35,600 units of recombinant factor VIII products was administered perioperatively. On postoperative day 95, a subcutaneous hematoma formed and immunosuppressive therapy with prednisolone was started based on an APTT of 66 seconds, factor VIII (FVIII) activity of 3%, and FVIII inhibitor of 1 BU/ml. During this treatment, the patient was hospitalized due to ankle joint bleeds and required hemostatic treatment, but the inhibitor disappeared and FVIII activity recovered to 30% after postoperative day 438 with cyclophosphamide. F8 analysis revealed the patient carried a heterozygosity of p.Arg391Cys, which has previously been categorized as cross-reacting material (CRM)-positive severe hemophilia A. No high-risk mutations for inhibitor development were found. We also report the results of a desmopressin acetate hydrate test administered to the patient to prepare for future treatment in case of hemorrhage, since high-dose FVIII administration may have been a factor in inhibitor development.

Correlation of ex vivo and in vivo ammonia production with L-asparaginase biological activity in adults with lymphoid malignancies.

Silent inactivation of L-asparaginase (L-Asp) represents rapid clearance of L-Asp by anti-L-Asp IgG antibodies without clinical symptoms. Measurement of L-Asp activity is the gold standard for diagnosis of silent inactivation, but this test is not commercially available in Japan as of 2023. We evaluated ex vivo and in vivo ammonia production in relation to L-Asp activity. Blood samples from ten adult patients treated with L-Asp were collected to measure ammonia levels and L-Asp activity before the first dose and 24 h after the last dose of L-Asp, during each cycle of treatment. Plasma ammonia levels were analyzed immediately and 1 h after incubation at room temperature, and ex vivo ammonia production was defined as the increase in ammonia concentration. Ex vivo ammonia production correlated with L-Asp activity (R2 = 0.741), and ammonia levels measured immediately after blood collection were moderately correlated with L-Asp activity (R2 = 0.709). One patient with extranodal NK/T-cell lymphoma showed an increase in ammonia levels during the first cycle, but no increase in ammonia levels or L-Asp activity after L-Asp administration during the second cycle. Both ex vivo and in vivo ammonia production and surrogate markers are used for L-Asp biological activity.

[FLT3-ITD and NPM1 mutation positive acute myeloid leukemia with cuplike blasts mimicking acute promyelocytic leukemia].

FMS-like tyrosine kinase 3 (FLT3) inhibitors improve the prognosis of FLT3-internal tandem duplication (ITD)-positive acute myeloid leukemia (AML). Case 1 is a 47-year-old male patient who presented with a white blood cell count (WBC) of 95,700/ml with 94% blast accompanied by cuplike nuclei, lactate dehydrogenase (LDH) of 2,434 IU/l, fibrin degradation products (FDP) of 476 mg/ml, and a bone marrow examination that revealed blastic marrow with chromosome 46, XY, positive FLT3-ITD, and positive nucleophosmin 1 (NPM1) mutation type A. Flow cytometry revealed that blasts were positive for CD33 and negative for CD34, CD117, and human leukocyte antigen-DR isotype (HLA-DR). The patient had no response to idarubicin combined cytarabine; however, qiuzartinib administration resulted in the first complete remission. Case 2 is a 71-year-old female patient, who presented with 94,900/ml of WBC with a 91% blast accompanied with cup-like nuclei, LDH of 19,03 IU/l, FDP of 112 mg/ml, and a peripheral blood examination that revealed chromosome 46, XX, positive FLT3-ITD, and positive NPM1 mutation type B. Flow cytometry revealed that blasts were positive for CD33 and negative for CD34, CD117, and HLA-DR. She had a partial response to venetoclax combined with azacytidine, and qiuzartinib administration resulted in the first complete remission. Both cases were CD34- and HLA-DR-negative with disseminated intravascular coagulation mimicking acute promyelocytic leukemia (APL). Additionally, recognizing the cuplike blasts is useful to differentiate FLT3 mutant AML from APL for the proper use of FLT3 inhibitors.

[Allogeneic hematopoietic stem cell transplantations for relapsed and refractory acute lymphoblastic leukemia following inotuzumab ozogamicin treatment].

Inotuzumab ozogamicin (InO) was administered in three cases of relapsed/refractory adult acute lymphoblastic leukemia (ALL) before allogeneic hematopoietic stem cell transplantation (allo-SCT). One case developed extremely severe sinusoidal obstruction syndrome (SOS) but recovered after receiving defibrotide therapy. A gap of 63 days in the SOS case was noted from the last administration of InO to allo-SCT, the duration was 133 and 86 days for the other two cases, and the remaining risk factors for SOS were comparable in the three cases. In contrast to gemtuzumab ozogamicin (GO), the interval between InO exposure and allo-SCT has not been reported as a risk for SOS. Nevertheless, this case suggests that the intervals should be as long as possible.

A case of lymphomatoid granulomatosis with central nervous system involvement successfully treated with IFNα.

Lymphomatoid granulomatosis (LYG) is a rare Epstein-Barr virus (EBV)-driven B-cell lymphoproliferative disease affecting mainly extranodal sites such as the lung, central nervous system (CNS), skin, kidney, and liver. We report a case of low-grade LYG involving the CNS that was successfully treated with interferon alpha (IFNα). A 69-year-old woman developed necrotic erythema of the skin and was initially diagnosed with pyoderma gangrenosum based on skin biopsy. She showed a limited response to prednisolone. Approximately 6 months after the initial onset, low-grade LYG was diagnosed after detection of CNS lesions on brain biopsy. The whole blood EBV-DNA load determined by real-time polymerase chain reaction was slightly elevated. Two months into IFNα therapy, skin and CNS lesions had responded favorably and the EBV-DNA load decreased. IFNα plays an important role in treatment of LYG through its antiproliferative, immunomodulatory, and anti-EBV effects. To our knowledge, this is the first case report of successful treatment with IFNα in Japan. Further investigation is necessary to determine optimal use of IFNα for LYG.

Risks of Muscle Atrophy in Patients with Malignant Lymphoma after Autologous Stem Cell Transplantation.

OBJECTIVE: Muscle atrophy is associated with autologous stem cell transplantation (ASCT)-related outcomes in patients with malignant lymphoma (ML). However, the impact of ASCT on muscle mass remains unclear in patients with ML. The aims of this study were to investigate changes in muscle mass and risk profiles for muscle atrophy after ASCT. METHOD: We enrolled 40 patients with refractory ML (age 58 [20-74] years, female/male 16/24, body mass index (BMI) 21.1 kg/m2 [17.1-29.6]). Psoas muscle mass was assessed using the psoas muscle index (PMI) before and after ASCT. STATISTICAL ANALYSIS USED: Independent factors associated with a severe decrease rate of change in PMI were evaluated by decision-tree analysis, respectively. RESULTS: PMI was significantly decreased after ASCT (4.61 vs. 4.55 cm2/m2; P=0.0425). According to the decision-tree analysis, the regimen was selected as the initial split. The rates of change in PMI were -5.57% and -3.97% for patients administered MCEC and LEED, respectively. In patients who were administered LEED, the second branching factor was BMI. In patients with BMI < 20.3 kg/m2, the rate of change in PMI was -7.16%. On the other hand, the rate of change in PMI was 4.05% for patients with BMI ≥ 20.3 kg/m2. CONCLUSION: We demonstrated that muscle mass decreased after ASCT in patients with ML. Patients who received MCEC and patients with low BMI were at risk for a decrease in muscle mass.

[Use of pegylated granulocyte colony-stimulating factor in dose-adjusted EPOCH-R therapy].

Dose-adjusted (DA)-EPOCH-R causes profound neutropenia requiring relatively long hospital stays with multiple doses of granulocyte colony-stimulating factor (G-CSF). A single-dose pegylated G-CSF (PEG-G-CSF) has been used for the treatment of chemotherapy-induced neutropenia. We retrospectively examined 15 patients (median age 61, range 33-75 years) treated with DA-EPOCH-R. In the first cycle of the DA-EPOCH-R therapy, a G-CSF preparation was used, and since the second cycle, the G-CSF and PEG-G-CSF use groups were divided. The median length of hospitalization after starting chemotherapy in the second-cycle DA-EPOCH-R was significantly shorter with PEG-G-CSF group (n=9) of 9 (7-13) days compared with G-CSF group (n=6) of 18 (15-22) days (P<0.001). Risk factors of febrile neutropenia, such as bone marrow invasion, performance status, serum albumin, and history of febrile neutropenia at the first DA-EPOCH-R cycle or previous chemotherapy were not significantly different for both groups, and the incidence of febrile neutropenia in PEG-G-CSF and G-CSF groups was 2.6% and 46.9%, respectively. These analyses suggest that PEG-G-CSF can be combined with DA-EPOCH-R without compromising treatment outcomes as compared with the daily dose of G-CSF.

Beneficial tyrosine kinase inhibitor therapy in a patient with relapsed BCR-ABL1-like acute lymphoblastic leukemia with CCDC88C-PDGFRB fusion.

BCR-ABL1-like acute lymphoblastic leukemia (ALL) is a neoplasm of lymphoblasts committed to the B-cell lineage that lack the BCR-ABL1 translocation but show a pattern of gene expression very similar to that seen in ALL with BCR-ABL1 with poor prognosis. A 22-year-old female was diagnosed with common-B-cell-ALL positive for CD10, CD19, CD22, CD79a, CD34, HLA-DR, and TdT in January 2017, and achieved complete remission (CR) with induction therapy, followed by consolidation therapy and maintenance therapy. In March 2020, 6 months after the completion of maintenance therapy, she relapsed. Inotuzumab ozogamicin (IO) was administered, and on day 28, bone marrow evaluation showed a morphologic CR. She had an HLA-identical sibling, and transplantation in her 2nd CR was planned. Because her ALL had been identified as BCR-ABL1-like ALL with CCDC88C-PDGFRB fusion, she was treated with imatinib for 2 months accompanied by 2 intrathecal methotrexate therapies, and 1 course of L-asparaginase, vincristine, and prednisolone in an outpatient setting. MRD analysis revealed potent efficacy of 2 months imatinib therapy; IgH MRD decreased from 1 × 10-2 to 1 × 10-3, and CCDC88C-PDGFRB/104ABL from 37.3 to 0. It is earnestly desired that well-designed clinical trials of TKI in ABL class-mutant BCR-ABL1-like ALL be conducted in Japan.

[Interleukin-6-producing paraganglioma mimicking multicentric Castleman disease].

Multicentric Castleman disease (MCD) comprises a heterogeneous group of lymphoproliferative disorders. Interleukin 6 (IL-6) plays an important role in the MCD pathophysiology. Here, we report the case of a 17-year-old Japanese man who presented with fever, headache, fatigue, and weight loss, with normal blood pressure. A movable mass was palpated in his lower abdomen. Laboratory tests revealed microcytic anemia and hypoalbuminemia, with elevated IL-6, sIL-2R, and vascular endothelial growth factor. Computed tomography of the abdomen demonstrated a 55-mm-diameter pelvic tumor and enlarged mesenteric lymph nodes. MCD was suspected, and the pelvic tumor resected. After the operation, his blood pressure rose slowly, and resulted to seizures of posterior reversible encephalopathy syndrome. Evaluation of hypertension revealed that plasma norepinephrine and normetanephrine concentrations were elevated, and pathological examinations showed that the resected tumor was positive for IL-6 and chromogranin-A. Therefore, we diagnosed the patient with IL-6-producing paraganglioma with MCD-mimicking symptoms. Moreover, IL-6-producing pheochromocytoma and paraganglioma should be included in differential diagnoses of MCD, even in normotensive patients.

Successful correction of factor V deficiency of patient-derived iPSCs by CRISPR/Cas9-mediated gene editing.

BACKGROUND: Factor V (FV) deficiency is a monogenic inherited coagulation disorder considered to be an ideal indication for gene therapy. To investigate the possibility of therapeutic application of genome editing, we generated induced pluripotent stem cells (iPSCs) from a FV-deficient patient and repaired the mutation of factor V gene (F5) using a clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated 9 (Cas9). METHODS: The patient's peripheral blood mononuclear cells were reprogrammed for iPSCs. The targeting vector was designed with homology arms against F5 containing the corrected sequence. Cas9 ribonucleoprotein (RNP) complex and targeting vector were electroporated into iPSCs. Gene-edited iPSCs were differentiated into hepatocyte-like cells (HLCs). RESULTS: The mutation of F5 in patient-derived iPSCs was repaired by CRISPR/Cas9. In concentrated culture supernatants of patient-derived iPS-HLCs, neither FV antigen nor activity was detected, while in those of gene-corrected iPS-HLCs, FV antigen and specific activity were 67.0 ± 13.1 ng/mL and 173.2 ± 41.1 U/mg, respectively. CONCLUSIONS: We successfully repaired the mutation of F5 using the CRISPR/Cas9 and confirmed the recovery of FV activity with gene-corrected iPS-HLCs. Gene-edited iPSCs are promising for elucidating the pathophysiology as well as for a modality of gene therapy.

Complete response following toxic epidermal necrolysis in relapsed adult T cell leukemia/lymphoma after haploidentical stem cell transplantation.

Allogeneic hematopoietic cell transplantation (allo-HSCT) is considered the curative treatment option in patients with aggressive adult T cell leukemia/lymphoma (ATLL), but the treatment of relapse after allo-HSCT remains a major challenge. We report a case of ATLL that was treated with sequential mogamulizumab (MOG) and lenalidomide (LEN) for early relapse after allo-HSCT. A 73-year-old Japanese male with acute-type ATLL underwent haploidentical-HSCT with post-transplant cyclophosphamide. He attained a complete response. However, ATLL relapse was diagnosed by biopsy of skin lesions that appeared on day 67. Discontinuation of immunosuppressant therapy alone did not result in improvement of ATLL, however, the skin lesions disappeared after an immune response was induced by sequential MOG and LEN. Following MOG and LEN, very serious toxic epidermal necrolysis (TEN) developed requiring high-dose intravenous immunoglobulin and methylprednisolone pulse therapy. Although graft-versus-host disease exacerbated and progressed to TEN, a complete response was achieved after successful treatment of TEN. These agents may thus enhance anti-ATLL activity by immune modulation. Further investigation is necessary to determine the optimal use of MOG and LEN in relapsed ATLL after allo-HSCT.