[Acute myeloid leukemia with central nervous system involvement successfully treated with gilteritinib].

A 69-year-old woman was referred to our hospital due to hyperleukocytosis. We diagnosed acute myeloid leukemia and started induction therapy with the CAG regimen (aclarubicin, cytarabine and filgrastim). However, the patient was refractory to the initial treatment and developed quadriplegia, and a cerebrospinal fluid (CSF) test showed elevated blasts. We then performed intrathecal chemotherapy, and the number of blasts in CSF gradually decreased. But only two cycles of intrathecal therapy were possible due to severe methotrexate-induced mucositis. The leukemia cells had fms-like kinase 3-internal tandem duplication (FLT3-ITD), so we started treatment with oral gilteritinib. The patient then achieved hematological complete remission. Her paralysis was also resolving, and the CSF was clear of blasts for more than 6 months. Some reports show that gilteritinib may penetrate the CNS, and this case also supports the effectiveness of gilteritinib on CNS leukemia.

[Epstein-Barr virus-associated lymphoproliferative disorders after BNT162b2 mRNA COVID-19 vaccination].

Epstein-Barr virus-associated lymphoproliferative disorders (EBV-LPD) is a rare disease characterized by persistent or recurrent inflammation accompanied by EBV infection of T or NK cells that is not self-limiting, and it is fatal, if untreated. After receiving the first dose of the BNT162b2 mRNA COVID-19 vaccine, a 79-year-old male presented to the hospital with a 2-week history of fever. Laboratory results indicated pancytopenia, elevated liver transaminase levels, hyperferritinemia, and hypofibrinogenemia. Computed tomography revealed hepatosplenomegaly, but lymphadenopathy was not observed. A bone marrow biopsy, a random skin biopsy, and a liver biopsy revealed no malignancy, but an infectious evaluation revealed EBV viremia (5.19 Log IU/ml). Flow cytometry and RT-PCR revealed that the EBV genome was localized in NK cells, suggesting the diagnosis of EBV-NK-LPD. We administered prednisolone, intravenous immunoglobulin, and etoposide, but the EBV-DNA load failed to decrease, and he died 2 months later. Recently, case reports of COVID-19 vaccination-related hemophagocytic lymphohistiocytosis have been published. Although the mechanisms and risk factors for EBV-LPD after BNT162b2 mRNA COVID-19 vaccination remain unknown, it is important to note the possibility of reactivation of EBV after COVID-19 vaccination to initiate early and targeted therapy.

CD20 positivity and white blood cell count predict treatment outcomes in Philadelphia chromosome-negative acute lymphoblastic leukemia patients ineligible for pediatric-inspired chemotherapy.

BACKGROUND: The efficacy of conventional chemotherapy and allogeneic hematopoietic stem cell transplantation (allo-HSCT) has been controversial as post-remission therapies for adult Philadelphia chromosome-negative acute lymphoblastic leukemia patients. METHODS: We retrospectively analyzed 96 adolescent and adult cases of Philadelphia chromosome-negative acute lymphoblastic leukemia to evaluate whether allo-HSCT should be performed after first complete remission (1CR). RESULTS: In total, 34 patients received chemotherapy followed by allo-HSCT (HSCT group) and 62 received chemotherapy alone (chemotherapy group). No significant differences in the event-free survival (EFS) or overall survival were observed between the two groups. In the chemotherapy group, use of pediatric regimens was significantly associated with favorable EFS, while high white blood cell (WBC) count and CD20 positivity were associated with poor outcome. In patients who received pediatric regimens, subsequent allo-HSCT did not influence EFS. In patients who received conventional chemotherapy (adult regimen), subsequent allo-HSCT did not improve EFS. High WBC count and CD20 positivity were also significantly associated with poor EFS in patients who received adult regimens. Patients with low WBC count and absence of CD20 who received adult regimens did not benefit from allo-HSCT. CONCLUSIONS: Allo-HSCT may not be required in the pediatric regimen-eligible patients; however, pediatric regimen-ineligible patients with either CD20 positivity or high WBC count should receive allo-HSCT after achieving 1CR. This study was registered at http://www.umin.ac.jp/ctr/ as #C000016287.

Early dynamics of chronic myeloid leukemia on nilotinib predicts deep molecular response.

Chronic myeloid leukemia (CML) is a myeloproliferative disorder caused by the BCR-ABL1 tyrosine kinase. Although ABL1-specific tyrosine kinase inhibitors (TKIs) including nilotinib have dramatically improved the prognosis of patients with CML, the TKI efficacy depends on the individual patient. In this work, we found that the patients with different nilotinib responses can be classified by using the estimated parameters of our simple dynamical model with two common laboratory findings. Furthermore, our proposed method identified patients who failed to achieve a treatment goal with high fidelity according to the data collected only at three initial time points during nilotinib therapy. Since our model relies on the general properties of TKI response, our framework would be applicable to CML patients who receive frontline nilotinib or other TKIs.

Optimal treatment strategy with nilotinib for patients with newly diagnosed chronic-phase chronic myeloid leukemia based on early achievement of deep molecular response (MR4.5 ): The phase 2, multicenter N-Road study.

For patients who have chronic myeloid leukemia (CML), one of the primary treatment options is administration of nilotinib 300 mg twice daily (BID). In previous studies which compared outcomes associated with nilotinib or imatinib treatment, nilotinib achieved a higher rate of deep molecular response (MR). We conducted a phase II, open-label, multicenter study to investigate an intrapatient nilotinib dose-escalation strategy for patients with newly diagnosed chronic-phase (CP) CML based on early MR4.5 achievement. The primary study endpoint was achievement of MR4.5 by 24 months following the initiation of nilotinib 300 mg BID. Fifty-three patients were enrolled, 51 received nilotinib, and 37 completed the treatment. An increase in the nilotinib dose (to 400 mg BID) was allowed when patients satisfied our criteria for no optimal response at any time point. The median (range) dose intensity was 600 (207-736) mg/day. Of 46 evaluable patients, 18 achieved an optimal response and 28 did not. Of the latter, nine patients underwent dose escalation to 400 mg BID, and none achieved MR4.5 . The remaining 19 patients could not undergo dose escalation, 12 (63%) because of adverse events (AEs), and 7 (37%) for non-AE related reasons. Four of these patients achieved MR4.5 . The MR4.5 rate by 24 months was 45.7%. The progression-free, overall and event-free survival were each 97.6%. No new safety concerns were observed. Our findings support the use of continuous nilotinib at a dose of 300 mg BID for newly diagnosed patients with CML-CP.

Involvement of Rap-1 activation and early termination of immune synapse in CTLA-4-mediated negative signal.

Cytotoxic T lymphocyte antigen 4 (CTLA-4) is a T cell co-stimulation receptor that delivers inhibitory signals upon activation. This inhibitory effect by CTLA-4 requires activation of small GTPase Rap-1. However, the precise mechanism underlying these negative signals remains unclear. Here, we show that CTLA-4-induced suppression of IL-2 production correlates with rapid destabilization of immunological synapse (IS) formation in murine normal T cell clones. Overexpression of Spa-1, a Rap-1-specific GTPase activating protein (GAP), abolished both Rap-1 activation and IL-2 suppression induced by CTLA-4. Although we failed to find any specific inhibition of activation of early signals upon CTLA-4 engagement, we found that CTLA-4 specifically up-regulates cell motility and suppresses prolonged accumulation of Talin at the contact area with antigen presenting cells upon antigen stimulation. These results suggest that Rap-1 is activated upon CTLA-4 ligation and mediates inhibitory signals through prevention of IS formation.

In vivo overexpression of CTLA-4 suppresses lymphoproliferative diseases and thymic negative selection.

Cytotoxic T lymphocyte antigen-4 (CTLA-4) induces major inhibitory signals for T cell activation. From analyses of TCR-transgenic (Tg) CTLA-4-deficient mice, it has been believed that CTLA-4 does not affect thymocyte development. To focus upon the in vivo function of CTLA-4 in thymocyte development from a different aspect, we have established Tg mice expressing either full-length CTLA-4 (FL-Tg) or a mutant CTLA-4 lacking the cytoplasmic region (truncated, TR-Tg), and analyzed thymocyte development. TR-T cells express much higher CTLA-4 on the cell surface than FL-T cells, in which most CTLA-4 was localized in intracellular vesicles. While CTLA-4-/- mice exhibit lymphoproliferative disease, neither of the Tg mice with CTLA-4-/- background developed the disorder. Although the development of thymocytes appeared normal in both Tg mice, in vivo depletion of double-positive thymocytes by injection of anti-CD3 Ab as well as the elimination of minor lymphocyte-stimulating antigen-reactive thymocytes were impaired in FL-Tg mice but not in TR-Tg mice. Functionally, cross-linking of CTLA-4 on thymocytes from FL-Tg mice, but not from TR-Tg mice, inhibited proliferation. These results reveal a potential role of CTLA-4, through its cytoplasmic domain, in the negative selection of thymocytes and in the prevention of lymphoproliferative disease.

Successful control of Epstein-Barr virus (EBV)-infected cells by allogeneic nonmyeloablative stem cell transplantation in a patient with the lethal form of chronic active EBV infection.

Chronic active Epstein-Barr virus infection (CAEBV) is a heterogeneous EBV-related disorder, ranging from mild/moderate forms to rapidly lethal disorders. The lethal form of CAEBV is characterized by multiple organ failure, hemophagocytic syndrome, and development of lymphomas. Allogeneic stem cell transplantation is considered as the only potentially curative treatment for the lethal form of CAEBV, but it is not always desirable because of the high incidence of regimen-related toxicities. A 17-year-old female with CAEBV, who was refractory to conventional therapies and considered to be unable to receive a myeloablative regimen because of multiple organ dysfunction, underwent allogeneic nonmyeloablative stem cell transplantation (allo-NST) before developing a hematological malignancy. She has been well without any signs of CAEBV for 27 months after allo-NST, and we confirmed that specific cytotoxic T lymphocyte activity against EBV was reconstituted. This outcome suggests that allo-NST can control CAEBV by reconstituting the host immunity against EBV.