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The primary central nervous system (CNS) presentation of lymphomatoid granulomatosis (LYG) is rare, and no standard therapy for LYG with primary CNS symptoms exists. CNS-LYG patients usually survive for only less than a year from diagnosis. This is the first report of high-grade primary CNS-LYG with monoclonality that was successfully treated with rituximab monotherapy, resulting in a durable remission for more than 1 year in a 66-year-old woman with pemphigus vulgaris who was also on immunosuppressive therapy.

We herein report a case of multiple myeloma and polyneuropathy, organomegaly, endocrinopathy, myeloma protein, and skin changes (POEMS) syndrome. The patient experienced exacerbated gait disturbance due to weakness and numbness in the lower limbs. Thoracic magnetic resonance imaging revealed an extramedullary tumor with spinal compression that required surgical resection. Plasmacytoma was diagnosed based on a biopsy. Radiation, betamethasone, and chemotherapy were therefore administered. Surgical removal of extramedullary tumors improved his symptoms, motor conduction velocity, and amplitude of the muscle action potential in the peroneal and tibial nerves, as shown by the nerve conduction study. Surgery also decreased the serum vascular endothelial growth factor levels. The patient required additional chemotherapy due to multiple myeloma and showed better outcomes nine months after discharge. The benefits of some treatments remain controversial due to the small number of patients. However, our findings reveal that an early diagnosis and comprehensive treatment may result in better outcomes in such patients.

Multiple myeloma (MM) is an incurable hematological malignancy. Despite the introduction of several novel drugs, most patients relapse. Biomarkers to identify the early signs of relapse will make it possible to adjust the therapeutic strategy before the disease worsens. Although understanding genetic changes is important for the treatment of MM, currently known biomarkers of relapse, including serum free-light chains and monoclonal paraproteins, are not associated with genetic changes. We therefore performed a multicenter study to examine the usefulness of circulating cell-free DNA (cfDNA) present in the peripheral blood (PB) plasma of patients as a biomarker for MM relapse. We identified several driver mutations by combined analysis of next-generation sequencing and existing databases of candidate oncogenes. Furthermore, relapse was detected more sensitively by monitoring the circulating cfDNA with these driver mutations than by conventional serum free-light chain examination. These results suggest the potential utility of cfDNA in the PB plasma of patients as a relevant early biomarker for MM relapse.

Background In a multinational phase 3 trial (VIALE-C), venetoclax plus low-dose cytarabine prolonged overall survival vs placebo plus low-dose cytarabine in patients with newly diagnosed acute myeloid leukaemia ineligible for intensive chemotherapy, although it was not statistically significant. Herein, we assess the benefit of venetoclax plus low-dose cytarabine in the Japanese subgroup of VIALE-C patients (n = 27). Methods VIALE-C, a randomized (2:1), double-blind study (NCT03069352), enrolled untreated patients (≥18 years) with acute myeloid leukaemia. Patients received venetoclax (600 mg days 1–28, 4-day ramp-up in cycle 1) or placebo in 28-day cycles with low-dose cytarabine (20 mg/m2 days 1–10). The primary endpoint was median overall survival. Results In the Japanese subgroup, at a 6-month follow-up from the primary analysis, median overall survival for venetoclax (n = 18) and placebo (n = 9), plus low-dose cytarabine, was 4.7 and 8.1 months, respectively (hazard ratio, 0.928, 95% confidence intervals : 0.399, 2.156). The rate of complete remission plus complete remission with incomplete blood count recovery was higher with venetoclax plus low-dose cytarabine (44.4%) vs placebo plus low-dose cytarabine (11.1%). All patients experienced at least 1 adverse event. The most common grade ≥3 adverse events with venetoclax or placebo, plus low-dose cytarabine, were febrile neutropenia (50.0% vs 44.4%, respectively) and thrombocytopenia (27.8% vs 44.4%, respectively). Serious adverse events were reported in 50.0 and 33.3% of patients in the venetoclax and placebo, plus low-dose cytarabine arms, respectively; pneumonia was the most common (22.2% each). Conclusions Limited survival benefit in the Japanese subgroup can be attributed to small patient numbers and to baseline imbalances observed between treatment arms, with more patients in the venetoclax plus low-dose cytarabine arm presenting poor prognostic factors. Venetoclax plus low-dose cytarabine was well tolerated in Japanese patients with acute myeloid leukaemia ineligible for intensive chemotherapy., In the Japanese subgroup of VIALE-C patients (n = 27), venetoclax plus low-dose cytarabine (LDAC) was well tolerated and showed high response vs placebo plus low-dose cytarabine in patients with acute myeloid leukaemia ineligible for intensive chemotherapy.

Anemia is a frequent manifestation of myelofibrosis (MF) and there is an unmet need for effective treatments in anemic MF patients. The REALISE phase 2 study (NCT02966353) evaluated the efficacy and safety of a novel ruxolitinib dosing strategy with a reduced starting dose with delayed up-titration in anemic MF patients. Fifty-one patients with primary MF (66.7%), post-essential thrombocythemia MF (21.6%), or post-polycythemia vera MF (11.8%) with palpable splenomegaly and hemoglobin

Oral iron preparations are used as first-line treatment for iron deficiency anemia (IDA), but their gastrointestinal side effects prevent patients from appropriate adherence. We recently conducted a randomized, double-blind, phase 3 non-inferiority study to evaluate the efficacy and safety of two dosages of ferric citrate hydrate (FC) compared with sodium ferrous citrate (SF) in patients with IDA. FC at both 500 and 1000 mg/day was non-inferior to SF at 100 mg/day in terms of the change in the hemoglobin concentration at Week 7 from baseline. Logistic regression analysis suggested that the cumulative proportion of patients who achieved the target hemoglobin concentration (≥ 13.0 g/dL in male patients and ≥ 12.0 g/dL in female patients) at Week 7 was highest among those treated with FC at 1000 mg/day, followed by SF at 100 mg/day and FC at 500 mg/day. Both dosages of FC were well tolerated in patients with IDA. The incidences of nausea and vomiting were significantly lower in the FC treatment groups than in the SF group. In conclusion, FC has potential to be an oral iron preparation with sufficient efficacy for the treatment of IDA and a lower risk of nausea and vomiting.

Radiation-induced myopathy (RIM) is a rare complication occurring years after radiotherapy. RIM basically occurs within the irradiation field, but some cases have been reported to be accommodated by myopathy outside the irradiation field, and the actual extent of RIM is obscure. The presented case also showed decreased MMT scores and abnormal needle electromyography results in the muscles outside the irradiated field, and the patient was initially thought to have RIM both within and outside the irradiated field. However, while systemic postmortem muscle sampling revealed prominent myopathy in line with RIM in the irradiated muscles, only mild myogenic changes that could be explained by other causes such as age-related sarcopenia, radiculopathy, and disuse atrophy were observed in the non-irradiated muscles. The number of biopsy sites in live patients is limited due to the invasive nature of the procedure, but we were privileged to systemically evaluate the extent of myopathy through multiple muscle sampling including muscles both inside and outside of the irradiation field because this was an autopsy case. Through the presented case, we conclude that RIM is a phenomenon most probably limited to the muscles within the irradiated field, and myopathy outside the irradiation is due to other causes.

Plerixafor was introduced to Japan in 2017 as a stem cell mobilization enhancement reagent, but the threshold for its use remains unclear. In this study, we assessed 57 patients treated with plerixafor (33 patients with multiple myeloma (MM) and 24 with malignant lymphoma (ML) and 152 patients without plerixafor administration. When CD34+ cell pre-counts were between 5.5 and 20 cells/μL in MM or 6 and 21 cells/μL in ML, the CD34+ cell count increased significantly, attaining the highest yield in response to plerixafor (achievement rate by one leukapheresis is 93.3% and 91.7% in MM and ML, at P < .001 and P = .012, respectively). In case the CD34+ cell pre-count was less than 5.5 cells/μL, an increase of at least 7 cells/μL from baseline by plerixafor was the necessary condition to achieve successful collection through a two-time leukapheresis. Monitoring CD34+ cell numbers might improve the collection efficiency and reduce the cost.

Diffuse large B cell lymphoma (DLBCL) is an aggressive disorder accounting for >30% of all lymphomas. Its prognosis is poor due to a high relapse rate. Spontaneous regression (SR) in DLBCL is rare, with only a few reported cases. Moreover, almost all of these were low-grade lymphomas with an average SR duration of 13 mo. As the cause of SR is unknown, there are many theories such as trauma, infection, medication, and an antitumor immune response. We present a patient with progressive DLBCL who demonstrated SR for >42 mo. Although treatment for lymphoma usually starts soon after diagnosis, insights into SR of lymphomas may lead to new treatment strategies.

Immunotherapy utilizing induced pluripotent stem cell (iPSC) technology has great potential. Functionally rejuvenated cytotoxic T lymphocytes (CTLs) can survive long-term as young memory T cells in vivo, with continuous tumor eradication. Banking of iPSCs as an unlimited “off-the-shelf” source of therapeutic T cells may be feasible. To generate safer iPSCs, we reprogrammed human papilloma virus type 16 (HPV16) E6-specific CTLs by Sendai virus vector without cotransduction of SV40 large T antigen. The iPSCs efficiently differentiated into HPV16-specific rejuvenated CTLs that demonstrated robust cytotoxicity against cervical cancer. The tumor-suppressive effect of rejuvenated CTLs was stronger and more persistent than that of original peripheral blood CTLs. These rejuvenated HPV16-specific CTLs provide a sustained tumor-suppressive effect even for epithelial cancers and constitute promising immunotherapy for cervical cancer., Graphical Abstract, In this article, Honda and colleagues show that safer iPSCs can be established from an HPV-CTL clone by Sendai virus vector without cotransduction of SV40 large T antigen. The iPSCs efficiently differentiated rejuvenated CTLs and exhibited a sustained cervical cancer-suppressive effect in vitro and in vivo.

Essential thrombocythemia (ET) mainly affects the elderly, but can also develop in women of childbearing age. The risk of miscarriage and other complications during pregnancy in ET patients are reported to be higher than that compared to the general population. Therefore, management of pregnancy in ET patients requires special considerations. Several groups recommend interferon (IFN) therapy for ET patients with high-risk pregnancies, but currently no guidelines are available in Japan. We report the outcomes of nine ET patients with ten consecutive high-risk pregnancies. All patients were successfully managed with IFN-α during their pregnancies. All patients also received aspirin and switched to unfractionated heparin around 36 weeks of gestation. As for the seven pregnancies in which IFN-α was started after detection of pregnancy, median platelet counts decreased from 910 to 573 × 109/L after 2 months of IFN-α therapy, and median platelet counts at the time of delivery for all ten pregnancies was 361 × 109/L. All patients gave birth to healthy children. IFN-α was well tolerated, safe, and effective as a cytoreductive therapy for all patients. Although evidence is limited and the use of IFN is not approved in Japan, we suggest considering IFN therapy for high-risk ET pregnancies.

We conducted a large-scale, nationwide retrospective study of Japanese patients who were diagnosed with essential thrombocythemia based on the diagnostic criteria in the World Health Organization classification. We investigated clinical characteristics, survival rates, and the incidence of thrombohemorrhagic events as well as risk factors for these events. A total of 1152 patients were analyzed in the present study. Median age at diagnosis was 65 years, the median platelet count was 832 × 109/L, and the positive mutation rates of JAK2V617F, CALR, and MPL were 62.8, 25.1, and 4.1%, respectively. Compared with European and American patients, Japanese patients were more likely to have cardiovascular risk factors and less likely to have systemic symptoms including palpable splenomegaly. Thrombocytosis was identified as a risk factor for hemorrhagic events and prognosis, but not for thrombotic events. The prognostic factors and risk classifications reported in Europe and the United States were generally applicable to Japanese patients. Regarding transformations, secondary myelofibrosis progressed in a time-dependent manner, but progression to acute leukemia was low in "true" ET patients. Skin cancers were less common and gastrointestinal cancers more common as secondary malignancies in Japanese patients, suggesting ethnic differences.

A subset of essential thrombocythemia (ET) cases are negative for disease-defining mutations on JAK2, MPL, and CALR and defined as triple negative (TN). The lack of recurrent mutations in TN-ET patients makes its pathogenesis ambiguous. Here, we screened 483 patients with suspected ET in a single institution, centrally reviewed bone marrow specimens, and identified 23 TN-ET patients. Analysis of clinical records revealed that TN-ET patients were mostly young female, without a history of thrombosis or progression to secondary myelofibrosis and leukemia. Sequencing analysis and human androgen receptor assays revealed that the majority of TN-ET patients exhibited polyclonal hematopoiesis, suggesting a possibility of reactive thrombocytosis in TN-ET. However, the serum levels of thrombopoietin (TPO) and interleukin-6 in TN-ET patients were not significantly different from those in ET patients with canonical mutations and healthy individuals. Rather, CD34-positive cells from TN-ET patients showed a capacity to form megakaryocytic colonies, even in the absence of TPO. No signs of thrombocytosis were observed before TN-ET development, denying the possibility of hereditary thrombocytosis in TN-ET. Overall, these findings indicate that TN-ET is a distinctive disease entity associated with polyclonal hematopoiesis and is paradoxically caused by hematopoietic stem cells harboring a capacity for cell-autonomous megakaryopoiesis.

Small cell lung cancer (SCLC) is a type of high-grade neuroendocrine carcinoma. It initially responds to chemotherapy but rapidly becomes chemoresistant and it is highly proliferative. The prognosis in SCLC is poor. We have established a novel SCLC cell line, SCLC-J1, from a malignant pleural effusion in a patient with advanced SCLC. SCLC-J1 cells express ganglioside GD2, CD276, and Delta-like protein 3. RB1 is lost. These features of the new SCLC cell line may be useful in understanding the cellular and molecular biology of SCLC and in designing better treatment., Highlight • A novel small lung cancer cell line, SCLC-J1, was successfully established. • SCLC-J1 cells express the tumor-specific antigens ganglioside GD2, CD276, and Delta-like protein 3. RB1 is lost. • SCLC-J1 will provide insights into SCLC biology that may permit better therapeutic targeting.

The global COVID-19 pandemic has been reported to inflict higher death rates in patients with hematologic malignancies compared with the general population.1 Proposed theoretical mechanisms include lymphopenia, which is often seen in this patient group, and suppressed immune function owing to the hematologic malignancy itself or because of treatment. We report the first case of persistent COVID-19 pneumonia that was still ongoing at 2 months after onset in a patient with follicular lymphoma (FL) undergoing rituximab maintenance therapy. The patient failed to develop anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunoglobulin (Ig)G and IgM antibodies, which was most probably the result of prior rituximab therapy, and thus provoked this unusual chronic state of COVID-19 pneumonia.

Activation-induced cell death (AICD) mediated by the Fas/Fas ligand (FasL) system plays a key role in regulating immune response. Although normal natural killer (NK) cells use this system for their homeostasis, malignant NK cells seem to disrupt the process. Extranodal NK/T-cell lymphoma, nasal type (ENKL) is a rare but fatal disease, for which novel therapeutic targets need to be identified. We confirmed that ENKL-derived NK cell lines NK-YS and Hank1, and primary lymphoma cells expressed procaspase-8/FADD-like interleukin-1β-converting enzyme (FLICE) modulator and cellular FLICE-inhibitory protein (c-FLIP), along with Fas and FasL. Compared with Fas-sensitive Jurkat cells, NK-YS and Hank1 showed resistance to Fas-mediated apoptosis in spite of the same expression levels of c-FLIP and the death-inducing signaling complex (DISC) formation. Unexpectedly, the long isoform of c-FLIP (c-FLIPL ) was coimmunoprecipitated with Fas predominantly in both ENKL-derived NK cell lines after Fas ligation. Indeed, c-FLIPL was more sufficiently recruited to the DISC in both ENKL-derived NK cell lines than in Jurkat cells after Fas ligation. Knockdown of c-FLIPL per se enhanced autonomous cell death and restored the sensitivity to Fas in both NK-YS and Hank1 cells. Although ENKL cells are primed for AICD, they constitutively express and efficiently utilize c-FLIPL , which prevents their Fas-mediated apoptosis. Our results show that c-FLIPL could be a promising therapeutic target against ENKL.

Unique frameshift mutations in the calreticulin (CALR) gene, which encodes an endoplasmic reticulum (ER)-localized molecular chaperone, have been identified in patients with essential thrombocythemia (ET) and primary myelofibrosis (PMF), which are subgroups of myeloproliferative neoplasms (MPNs). In this review, we discuss the current understanding of the consequences of these mutations with regard to tumorigenesis and/or signal transduction. Expression of mutant CALR induces thrombocytosis in animal models, producing the phenotype of ET. Mutant CALR preferentially interacts with and activates the thrombopoietin receptor MPL, resulting in MPL-dependent cellular transformation. A novel carboxyl-terminal sequence generated by a frameshift mutation in CALR mediates intermolecular interactions to form homomultimers and induces structural changes required for MPL binding and activation. The homomultimerized mutant CALR behaves similarly to a cytokine, stabilizing homodimerized MPL by binding to immature MPL N-glycans. Mutant CALR may engage with MPL in the ER, but fails to dissociate, conveying MPL to the cell surface where MPL activation is likely to occur. Collectively, cell-autonomous and constitutive activation of MPL is a cause of MPNs that are mediated by mutant CALR. Novel therapeutic strategies for treating MPNs that target these mechanisms should, therefore, be developed.

Myelofibrosis (MF) can occur due to a wide variety of causes including malignant lymphoma. We report a case of splenic marginal zone lymphoma complicated by MF mimicking primary myelofibrosis (PMF). The JAK2, CALR and MPL mutations are detected in more than 90% of PMF cases, and when detected, the diagnosis of PMF is usually straight forward. Mutational analysis should be done in all cases of MF, and in triple-negative cases, an exhaustive investigation of other causes of MF should be carried out before a diagnosis of triple-negative PMF is rendered.

Monocyte-derived fibrocytes recently garnered attention because the novel pathogenesis of myelofibrosis (MF), and suppression of fibrocyte differentiation by serum amyloid P remarkably improved MF. We previously revealed that human fibrocytes highly expressed signaling lymphocytic activation molecule F7 (SLAMF7) compared with macrophages and that SLAMF7high monocytes in the peripheral blood (PB) of MF patients were significantly elevated relative to those in healthy controls (HCs). In this study, we evaluated SLAMF7high monocyte percentage in the PB of HCs, myeloproliferative neoplasm (MPN) patients with MF, and MPN patients without MF by using a cross-sectional approach. We found that MPN patients with MF who harbored JAK2V617F had a significantly elevated SLAMF7high monocyte percentage, which correlated positively with the JAK2V617F allele burden. In addition, the serum concentration of interleukin-1ra (IL-1ra) was significantly correlated with the SLAMF7high monocyte percentage and JAK2V617F allele burden. These findings suggest that both SLAMF7high monocytes and IL-1ra could be useful noninvasive markers of MF onset. Furthermore, the JAK2V617F allele burden of SLAMF7high monocytes was significantly higher than that of SLAMF7low monocytes and could be a potential target of elotuzumab (Elo), an anti-SLAMF7 antibody used for treating multiple myeloma. Elo independently inhibited differentiation of fibrocytes derived not only from HCs but also from MF patients in vitro. Elo also ameliorated MF and splenomegaly induced by romiplostim administration in humanized NOG mice. In conclusion, an increase of SLAMF7high monocytes with higher JAK2V617F allele burden was associated with the onset of MF in MPN patients harboring JAK2V617F, and Elo could be a therapeutic agent for MPN patients with MF who harbor JAK2V617F.

Vitamin B6 (VB6) deficiency contributes to oncogenesis and tumor progression in certain cancers, and is prevalent in cancer patients in general. VB6 is also an essential element of heme synthesis, and deficiency can lead to anemia. Primary myelofibrosis (PMF) and secondary myelofibrosis (sMF) are myeloproliferative neoplasms often presenting with anemia along with other cytopenias. We performed a prospective study to determine whether PMF and sMF patients suffer from VB6 deficiency, and whether VB6-deficient patients show improvement of anemias with VB6 supplementation. Twelve PMF patients and 11 sMF patients were analyzed. A total of 16 of 23 patients (69.6%) were found to have VB6 deficiency, but VB6 supplementation with pyridoxal phosphate hydrate did not elevate hemoglobin levels in deficient patients. None of the patients presented with vitamin B12, iron, or copper deficiencies. Four patients showed serum folate levels below the lower limit of normal and eight patients showed serum zinc levels below the lower limit of normal; however, these deficiencies were marginal and unlikely to contribute to anemia. Compared to VB6-sufficient patients, VB6-deficient patients showed significantly lower serum folate levels and higher serum copper levels. Studies elucidating the relationship of VB6 deficiency and etiology of PMF/sMF are warranted.

Functionally rejuvenated induced pluripotent stem cell (iPSC)-derived antigen-specific cytotoxic T lymphocytes (CTL) are expected to be a potent immunotherapy for tumors. When L-asparaginase-containing standard chemotherapy fails in extranodal natural killer/T-cell lymphoma, nasal type (ENKL), no effective salvage therapy exists. The clinical course then is miserable. We demonstrate prolonged and robust eradication of ENKL in vivo by Epstein-Barr virus-specific iPSC-derived antigen-specific CTL, with iPSC-derived antigen-specific CTL persisting as central memory T cells in the mouse spleen for at least six months. The anti-tumor response is so strong that any concomitant effect of the programmed cell death 1 (PD-1) blockade is unclear. These results suggest that long-term persistent Epstein-Barr virus-specific iPSC-derived antigen-specific CTL contribute to a continuous anti-tumor effect and offer an effective salvage therapy for relapsed and refractory ENKL.

JAK2 V617F mutation increases the risk of thrombosis, and both ischemic and hemorrhagic strokes can occur in essential thrombocythemia (ET). The mechanisms underlying ischemic stroke in ET are diverse, and hemorrhagic stroke has rarely been reported in ET. Among 627 stroke patients, those identified as having ET were investigated retrospectively. A comprehensive systemic literature search of the PubMed database was also conducted. Two cases were extracted with the diagnosis of ET who developed SAH and then ischemic stroke. In Case 1, a 47-year-old woman developed SAH in the left high convexity. Eleven hours later, acute cerebellar infarction suddenly developed due to right vertebral artery dissection. In Case 2, a 70-year-old woman developed SAH in the right high convexity. Magnetic resonance angiography showed multifocal stenotic changes in intracranial arteries. Three days later, she developed acute brain infarcts in the right middle cerebral artery territory. Eight weeks later, multifocal stenotic lesions improved. The literature review revealed 5 patients with hemorrhagic stroke and 40 patients with ischemic stroke associated with ET. Age at onset varied, female gender predominated, and the frequency of JAK2 V617F mutation was high. Atherosclerotic vascular risk factors were more common in ischemic stroke, but not in hemorrhagic stroke. The current study describes rare cases of SAH accompanied by ischemic stroke secondary to ET along with a review of the current literature, implying specific mechanisms for cerebral artery disorders associated with JAK2 V617F mutation.

Acute megakaryoblastic leukemia (AMegL) is a rare hematological neoplasm most often diagnosed in children and is commonly associated with Down's syndrome (DS). Although AMegLs are specifically characterized and typically diagnosed by megakaryoblastic expansion, recent advancements in molecular analysis have highlighted the heterogeneity of this disease, with specific cytogenic and genetic alterations characterizing different disease subtypes. Areas covered: This review will focus on describing recurrent molecular variations in both DS and non-DS pediatric AMegL, their role in promoting leukemogenesis, their association with different clinical aspects and prognosis, and finally, their influence on future treatment strategies with a number of specific drugs beyond conventional chemotherapy already under development. Expert opinion: Deep understanding of the genetic and molecular landscape of AMegL will lead to better and more precise disease classification in terms of diagnosis, prognosis, and possible targeted therapies. Development of new therapeutic approaches based on these molecular characteristics will hopefully improve AMegL patient outcomes.

Background The phase 3 VIALE-A trial (NCT02993523) reported that venetoclax-azacitidine significantly prolonged overall survival compared with placebo-azacitidine in patients with newly diagnosed acute myeloid leukemia ineligible for intensive chemotherapy. Herein, efficacy and safety of venetoclax-azacitidine are analyzed in the Japanese subgroup of VIALE-A patients. Methods Eligible Japanese patients were randomized 2:1 to venetoclax-azacitidine (N = 24) or placebo-azacitidine (N = 13). Primary endpoints for Japan were overall survival and complete response (CR) + CR with incomplete hematologic recovery (CRi). Venetoclax (target dose 400 mg) was given orally once daily. Azacitidine (75 mg/m2) was administered subcutaneously or intravenously on Days 1–7 of each 28-day cycle. Results Median follow-up was 16.3 months (range, 1.0–20.3). Median overall survival was not reached with venetoclax-azacitidine (hazard ratio 0.409 and 95% confidence interval: 0.151, 1.109); overall survival estimate was higher with venetoclax-azacitidine than placebo-azacitidine at 12 (67 and 46%) and 18 months (57 and 31%), respectively. CR and CRi rates were 67% with venetoclax-azacitidine and 15% with placebo-azacitidine. Most common any-grade adverse events were febrile neutropenia (79 and 39%), thrombocytopenia (54 and 77%), constipation (54 and 54%) and decreased appetite (54 and 38%) in the venetoclax-azacitidine and placebo-azacitidine arms, respectively. Only 1 patient in the venetoclax-azacitidine arm, and no patients in the placebo-azacitidine arm, had grade 4 febrile neutropenia that led to treatment discontinuation. Conclusions This Japanese subgroup analysis of VIALE-A demonstrates comparable safety and efficacy outcomes compared with the global study and supports venetoclax-azacitidine as first-line standard-of-care for Japanese treatment-naive patients with acute myeloid leukemia who are ineligible for intensive chemotherapy.

Trio-next generation sequencing is useful to identify undiagnosed inherited diseases. We have attended a patient with trigenic ADH5/ALDH2/ADGRV1 pathogenic variants, which caused two distinct diseases, myelodysplastic syndrome and Usher syndrome. Whole genome sequencing of peripheral blood from the patient and his parents were applied to identify disease-causing genes. Sanger sequencing was performed to validate the identified ADH5/ALDH2/ADGRV1 variants. Our results identified disease-associated variants in ADGRV1 (disease inheritance autosomal recessive) and in ADH5 (disease inheritance also autosomal recessive) and a variant in ALDH2 (disease inheritance autosomal dominant). Although the variants identified in ADH5 and ALDH2 have been reported, their co-existence in association with disease-causing variation in a third gene has not. They broaden the spectrum of ADGRV1 in Usher syndrome. Findings on next generation sequencing guided rapid and accurate diagnosis, resulting in patient-tailored therapeutic intervention., Highlights • Trigenic ADH5 / ALDH2 / ADGRV1 ​variants in myelodysplastic syndrome with Usher syndrome were identified. • Two novel pathogenic frameshift variants in ​ADGRV1 ​in compound heterozygous state with Usher syndrome type II were described. • Findings on next generation sequencing guided rapid and accurate diagnosis, resulting in patient-tailored therapy., ADH5/ALDH/ADGRV1 variants, Myelodysplastic syndrome, Trigenic mutations, Trio-next generation sequencing, Usher syndrome.

Background: We previously reported elsewhere of a follicular lymphoma patient suffering from persistent COVID-19 pneumonia that was still ongoing at 2 months after onset. Materials and Methods: We provide a follow-up report of the case along with a literature review of immunocompromised lymphoma patients experiencing prolonged COVID-19 infections. Results: Although requiring a full 1 year, the presented case eventually achieved spontaneous resolution of COVID-19 pneumonia. Anti-SARS-CoV-2 antibodies could not be detected throughout the disease course, but COVID-19-directed T-cell response was found to be intact. The patient also developed secondary immune thrombocytopenia subsequent to COVID-19 pneumonia. We found 19 case reports of immunocompromised lymphoma patients with prolonged COVID-19 infections in the literature. All 5 patients who died did not receive convalescent plasma therapy, whereas resolution of COVID-19 infection was achieved in 8 out of 9 patients who received convalescent plasma therapy. Conclusions: We demonstrate through the presented case that while time-consuming, resolution of COVID-19 infections may be achieved without aid from humoral immunity if cellular immunity is intact. Immunocompromised lymphoma patients are at risk of a prolonged disease course of COVID-19, and convalescent plasma therapy may be a promising approach in such patients. Micro-abstract: Persisting clinical infections and prolonged viral shedding of COVID-19 in immunocompromised patients is a rapidly emerging issue of concern. Persisting COVID-19 infections not only threaten the well-being of the patient, but may also be a potential long-term contagious threat to the environment, and special care must be provided concerning in-hospital isolation and self-quarantine periods. We report an immunocompromised lymphoma patient recovering from a 1-year disease course of COVID-19 pneumonia along with a review of the literature.

Ruxolitinib (RUX), a JAK1/2-inhibitor, is effective for myeloproliferative neoplasm (MPN) with both JAK2V617 F and calreticulin (CALR) mutations. However, many MPN patients develop resistance to RUX. Although mechanisms of RUX-resistance in cells with JAK2V617 F have already been characterized, those in cells with CALR mutations remain to be elucidated. In this study, we established RUX-resistant human cell lines with CALR mutations and characterized mechanisms of RUX-resistance. Here, we found that RUX-resistant cells had high levels of MPL transcripts, overexpression of both MPL and JAK2, and increased phosphorylation of JAK2 and STAT5. We also found that mature MPL proteins were more stable in RUX-resistant cells. Knockdown of MPL in RUX-resistant cells by shRNAs decreased JAK/STAT signaling. Immunoprecipitation assays showed that binding of mutant CALR to MPL was increased in RUX-resistant cells. Reduction of mutated CALR decreased proliferation of the resistant cells. When resistant cells were cultured in the absence of RUX, the RUX-resistance was reversed, with reduction of the mutant-CALR/MPL complex. In conclusion, MPL overexpression induces higher levels of a mutant-CALR/MPL complex, which may cause RUX-resistance in cells with CALR mutations. This mechanism may be a new therapeutic target to overcome RUX-resistance.

Discrimination of Philadelphia‐negative myeloproliferative neoplasms (Ph‐MPNs) from reactive hypercytosis and myelofibrosis requires a constellation of testing including driver mutation analysis and bone marrow biopsies. We searched for a biomarker that can more easily distinguish Ph‐MPNs from reactive hypercytosis and myelofibrosis by using RNA‐seq analysis utilizing platelet‐rich plasma (PRP)‐derived RNAs from patients with essential thrombocythemia (ET) and reactive thrombocytosis, and CREB3L1 was found to have an extremely high impact in discriminating the two disorders. To validate and further explore the result, expression levels of CREB3L1 in PRP were quantified by reverse‐transcription quantitative PCR and compared among patients with ET, other Ph‐MPNs, chronic myeloid leukemia (CML), and reactive hypercytosis and myelofibrosis. A CREB3L1 expression cutoff value determined based on PRP of 18 healthy volunteers accurately discriminated 150 driver mutation–positive Ph‐MPNs from other entities (71 reactive hypercytosis and myelofibrosis, 6 CML, and 18 healthy volunteers) and showed both sensitivity and specificity of 1.0000. Importantly, CREB3L1 expression levels were significantly higher in ET compared with reactive thrombocytosis (P, CREB3L1 expression in platelet RNA can completely discriminate Philadelphia‐negative myeloproliferative neoplasms from other entities including reactive hypercytosis and myelofibrosis. The sensitivity and specificity of this testing are both 1.0000.

Patients with primary myelofibrosis (PMF) have a poorer prognosis than those with other subtypes of myeloproliferative neoplasms (MPNs). To investigate the relationship between gene mutations and the prognosis of Japanese PMF patients, we analyzed mutations in 72 regions located in 14 MPN-relevant genes (CSF3R, MPL, JAK2, CALR, DNMT3A, TET2, EZH2, ASXL1, IDH1/2, SRSF2, SF3B1, U2AF1, and TP53) utilizing a target resequencing platform. In our cohort, ASXL1 mutations were more frequently detected in both overt and prefibrotic PMF patients than other mutations. The frequency of ASXL1 mutations was slightly higher among overt PMF patients than among prefibrotic PMF patients (44.6% vs 25.0%, FDR = 0.472). Decision tree classification algorithms revealed that ASXL1, EZH2, and SRSF2 mutations were associated with a poor prognosis for overt PMF. Overall survival was significantly shorter in patients harboring ASXL1, EZH2, or SRSF2 mutations than in those without these mutations (p = 0.03). These results suggest that, as reported in Western countries, MIPSS70 is applicable to Japanese PMF patients and ASXL1, EZH2, and SRSF2 mutations may be utilized as surrogate markers of a poor prognosis.

Myeloproliferative neoplasms (MPNs), including polycythemia vera, essential thrombocythemia (ET), and primary myelofibrosis, mainly occur in older patients, but have also been reported in younger patients. A “second peak” occurs in female patients in their thirties, particularly in ET; thus, the management of pregnancy is often discussed. We herein present the case of a 33-year-old woman with a high platelet count and multiple placental infarcts during delivery who was subsequently diagnosed with ET. Although there are no worldwide guidelines for the management of MPNs in pregnancy, the risk of thrombosis is markedly increased in these patients, and antithrombotic therapy should be considered.

Splicing factor gene mutations are found in 60-70% of patients with myelodysplastic syndromes (MDS). We investigated the effects of splicing factor gene mutations on the diagnosis, patient characteristics, and prognosis of MDS. A total of 106 patients with MDS were included. The percentage of patients with MDS with ring sideroblasts (14.15%) as per the 2017 WHO classification was significantly higher than that of patients with refractory anemia with ring sideroblasts (2.88%) as per the 2008 WHO classification (P = 0.005). Splicing factor mutations were detected in 32 patients (13 SF3B1, 8 U2AF1, and 11 SRSF2), and the mutations were mutually exclusive. Significant differences were observed in the mean corpuscular volume, platelet count, bone marrow myeloid:erythroid ratio, and megakaryocyte count in patients with different mutations. SRSF2 mutations were associated with a high cumulative incidence of red blood cell transfusion dependence, while SF3B1 mutations were associated with a low cumulative incidence of platelet concentrate transfusion dependence. Presence of SF3B1 mutation was a significant univariate predictor of overall survival, but become nonsignificant in the multivariate model. Although many factors also could affect survival, these results suggest that splicing factor mutations contribute to distinct MDS phenotypes, including patient characteristics and clinical courses.

The signaling lymphocytic activation molecule family (SLAMF7; also known as CS1 or CD319) is highly expressed on plasma cells from multiple myeloma (MM) as well as natural killer (NK) cells and is a well-known therapeutic target of elotuzumab. The objective of this study was to evaluate the clinical significance of serum soluble SLAMF7 (sSLAMF7) levels in patients with MM (n=103) and furthermore the impact of sSLMF7 on the antitumor activity of anti-SLAMF7 antibody. Thirty-one percent of MM patients, but not patients with monoclonal gammopathy of undetermined significance and healthy controls, had detectable levels of serum sSLAMF7, which were significantly increased in advanced MM patients. Further, MM in sSLAMF7-postive patients exhibited aggressive clinical characteristics with shorter progression-free survival times in comparison with sSLAMF7-negative patients. In responders to MM therapy, the levels of sSLAMF7 were undetectable or decreased compared with those before treatment. In addition, the anti-SLAMF7 antibody-mediated antibody-dependent cellular cytotoxicity of NK cells against MM cell lines was inhibited by recombinant SLAMF7 protein. Thus, our findings suggest that high concentrations of sSLAMF7, which could transiently suppress the therapeutic effects of elotuzumab, may be a useful indicator of disease progression in MM patients.

Background Acquired von Willebrand syndrome (aVWS) is a rare bleeding disorder with laboratory findings similar to those of congenital von Willebrand disease (VWD). Patients with aVWS may require prophylactic treatment to prevent excessive bleeding following surgery. To our knowledge, to date, there have been no reports on perioperative management for breast cancer patients with aVWS. Case presentation A 60-year-old woman with breast cancer was diagnosed with aVWS due to polycythemia vera. Pre-operative laboratory testing showed a high platelet count and low von Willebrand factor (VWF) activity. The VWF activity did not improve despite an attempt to suppress platelet count with hydroxyurea. Therefore, we decided to perioperatively supplement with plasma-derived factor VIII (FVIII) containing von Willebrand factor (FVIII/VWF concentrates) to perform curative surgery for breast cancer safely. Consequently, the patient did not develop hemorrhage during/after surgery and was discharged on postoperative day 7, as planned, without problems. Conclusions For a patient with aVWS, which carries a high risk of hemorrhage during the perioperative period, initiation of appropriate management like supplementation of FVIII/VWF concentrates might enable safe curative surgery for breast cancer, and collaboration with the hematology department is critical.

The majority of patients with Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs) harbor JAK2, CALR, or MPL mutations. We compared clinical manifestations of different subtypes of JAK2 and CALR mutations in Japanese patients with MPNs. Within our cohort, we diagnosed 166 patients as polycythemia vera (PV), 212 patients as essential thrombocythemia (ET), 23 patients as pre-primary myelofibrosis (PMF), 65 patients as overt PMF, and 27 patients as secondary myelofibrosis following the 2016 WHO criteria. Compared to patients with JAK2V617F-mutated PV, JAK2 exon 12-mutated PV patients were younger, showed lower white blood cell (WBC) counts, lower platelet counts, higher red blood cell counts, and higher frequency of thrombotic events. Compared to JAK2-mutated ET patients, CALR-mutated ET patients were younger, showed lower WBC counts, lower hemoglobin levels, higher platelet counts, and fewer thrombotic events. CALR type 1-like mutation was the dominant subtype in CALR-mutated overt PMF patients. Compared with JAK2V617F-mutated ET patients, JAK2V617F-mutated pre-PMF patients showed higher LDH levels, lower hemoglobin levels, higher JAK2V617F allele burden, and higher frequency of splenomegaly. In conclusion, Japanese patients with MPNs grouped by different mutation subtypes exhibit characteristics similar to those of their Western counterparts. In addition, ET and pre-PMF patients show different characteristics, even when restricted to JAK2V617F-mutated patients.

Aims Indolent T-lymphoblastic proliferation (iT-LBP) is a non-clonal benign condition showing extrathymic proliferation of T-lymphoblasts positive for CD3, CD4, CD8, and TdT. Isolated iT-LBP has been observed, but the majority of iT-LBP have been seen in conjunction with other disorders including Castleman disease, hepatocellular carcinoma, follicular dendritic cell tumors, angioimmunoblastic T-cell lymphoma, myasthenia gravis, and acinic cell carcinoma (ACC). The clinical course of iT-LBP is indolent, and no therapy is usually required. A major concern is misdiagnosis for T-lymphoblastic lymphoma, and a correct diagnosis of iT-LBP often requires not only pathological analysis but also a cautious monitoring of the clinical course. The aim of this report is to broaden knowledge of this yet not well recognized entity to pathologists and physicians Methods and Results We report a case of iT-LBP concomitant to ACC, along with a literature review of all 14 cases of iT-LBP reported to date Conclusions iT-LBP should always be considered as a differential diagnosis of T-lymphoblastic lymphoma as the two disorders show extremely resembling traits. This article is protected by copyright. All rights reserved.

Myelofibrosis (MF) is associated with a significant symptom burden that severely impacts patient quality-of-life (QoL). Ruxolitinib, a potent Janus kinase 1 (JAK1)/JAK2 inhibitor, led to substantial improvements in splenomegaly, MF-associated symptoms, and QoL in the phase 3 COMFORT studies, proving superior to placebo and best available therapy. This study evaluated the effect of ruxolitinib on symptoms and QoL in Japanese patients with MF.A pooled analysis of studies A2202 (NCT01392443) and AJP01 (NCT02087059) of ruxolitinib in Japanese patients with MF (n = 81) was conducted. Changes in total symptom score (TSS) and the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 were summarized.Most patients received a starting dose of 15 or 20 mg twice daily (BID) and had a final titrated dose of ≥10 mg BID. Overall, 67.7% (44/65) achieved a ≥50% reduction from baseline in TSS at week 24. Reductions in TSS were seen in every dose group; the greatest reductions occurred in patients with a final titrated dose of 20 or 25 mg BID. Improvements in QoL were seen in patients who achieved a ≥50% reduction in TSS. Generally, improvements in TSS and individual symptoms correlated with reductions in spleen size, with those having a ≥35% reduction in spleen volume having the greatest improvements.Consistent with COMFORT-I, ruxolitinib provided substantial improvements in symptoms and QoL in Japanese patients with MF, with higher doses of ruxolitinib associated with better responses.

Hypereosinophilic syndrome (HES) is a systemic disease characterized by an increased peripheral blood eosinophil count accompanied by systemic organ dysfunction. HES is classified into idiopathic HES, primary (neoplastic) HES (HESN), and secondary (reactive) HES (HESR). In this case report, a patient who developed peripheral blood eosinophilia and granulation tissue in the pharynx and paranasal sinus, which was initially diagnosed as chronic eosinophilic leukemia (CEL), categorized as HESN, but was eventually identified after the patient had died as natural killer/T-cell (NK/T) lymphoma, nasal type (ENKL), categorized as HESR, is presented. ENKL-induced HES is very rare but must be considered.

Background: Essential thrombocythemia (ET) is a subtype of chronic myeloproliferative neoplasms (MPN) characterized by thrombocytosis and disease-related symptoms, which may be difficult to manage. Patients with ET are also at higher risk of thrombosis and hemorrhage. Ideal therapeutic approaches should achieve adequate cytoreduction, reduce the risk of thrombo-hemorrhagic complications, and prevent progression to post-ET myelofibrosis (PET-MF) or secondary acute myeloid leukemia (AML). Low-dose aspirin with hydroxyurea (HU) is typically given as first-line therapy in high-risk patients. However, approximately 20-40% of ET patients become HU-intolerant or -resistant. In ET, resistance and/or intolerance portend an increased risk of thrombosis, hemorrhage, disease transformation and death. There is a paucity of prospective clinical trial data to guide management of ET patients who are HU resistant or intolerant. P1101 is a next generation monopegylated interferon (IFN) alfa-2b, developed specifically to treat MPNs, including ET. Study Design and Methods: The SURPASS-ET trial (NCT04285086) is a Phase 3, open-label, multicenter, randomized, active-controlled study to assess the efficacy, safety, tolerability, and pharmacokinetics (PK) of P1101 after 12 months of treatment compared with anagrelide as second line therapy for subjects with ET who have shown resistance or intolerance to HU. The primary endpoint is durable modified ELN composite response at 9 and 12 months from dosing. Cochran-Mantel-Haenszel test will be used for comparing the primary endpoint in the two treatment arms. The PK parameters of P1101, including (but not limited to) C min, T max, C max, and area-under-curve (AUC) will be derived using PPK analysis and the relationship between exposure and efficacy and safety endpoints will be examined using E-R analysis. Evaluation of efficacy will include clinical laboratory assessments, allelic burden measurements of CALR, JAK2, and MPL, spleen size measurements, bone marrow sampling (optional), EQ-5D-3L, and MPN Symptom Assessment Form Total Symptom Score (MPN-SAF TSS) assessments. A total of 130 randomized subjects is planned to detect a difference of 40% (P1101) versus 15% (anagrelide) in durable ELN response rate with 90% power at alpha level = 0.05 using the chi-square test. To account for possible non-evaluability (e.g., no follow-up data), approximately 160 subjects will be randomized in this study to get 130 completed patients. Because of uncertainty in the assumptions on which the calculation of the sample size is based, an interim analysis for sample size adjustment will be implemented. Major inclusion criteria include subjects diagnosed with high-risk ET (either older than 60 years and JAK2V617F-positive at screening or having disease-related thrombosis or hemorrhage in the past), diagnosed according to the World Health Organization (WHO) 2016 criteria, documented resistance/intolerance to HU and IFN naïve or anti-P1101 binding antibody negative. Key exclusion criteria include pregnant females, significant cardiovascular disease, documented autoimmune disease and a history or presence of clinically significant depression or neurological disease. The study involves approximately 65 sites across the US, Taiwan, Japan, China, Hong Kong, Singapore, S. Korea, Canada, and Europe. To-date 55 patients (54 Asians, 1 Caucasian) have been randomized. The mean and median age at recruitment was 58.9 years (SD: 14.34) and 63 years (range 21 to 80 years) respectively. Twenty-seven men (49.1%) and twenty-eight women (50.9%) were recruited. Forty-two subjects (76.4%) had a TSS < 20. The study is being overseen by a Data Safety Monitoring Board (DSMB). Figure 1 Figure 1. Disclosures Mesa: Gilead: Research Funding; Promedior: Research Funding; AOP: Consultancy; Incyte Corporation: Consultancy, Research Funding; Abbvie: Research Funding; Genentech: Research Funding; La Jolla Pharma: Consultancy; Novartis: Consultancy; Sierra Oncology: Consultancy, Research Funding; Samus: Research Funding; Pharma: Consultancy; CTI: Research Funding; Celgene: Research Funding; Constellation Pharmaceuticals: Consultancy, Research Funding; CTI: Research Funding. Komatsu: Fujifilm Wako Pure Chemical Corporation: Research Funding; Fuso Pharmaceutical Industries, Ltd.: Research Funding; Japan Tobacco Inc.: Consultancy; Otsuka Pharmaceutical Co. Ltd: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis Pharma KK: Consultancy, Research Funding, Speakers Bureau; Shire Japan KK: Consultancy, Research Funding, Speakers Bureau; PharmaEssentia Japan KK: Consultancy, Current Employment, Research Funding; Chugai Pharmaceutical Co., Ltd.: Research Funding; Kyowa Hakko Kirin Co., Ltd.: Research Funding. Sato: PharmaEssentia Japan KK: Current Employment. Qin: PharmaEssentia Corp.: Current Employment. Urbanski: PharmaEssentia Corporation: Current Employment. Shih: PharmaEssentia Corporation: Consultancy. Zagrijtschuk: PharmaEssentia U.S.A. Corp.: Current Employment. Zimmerman: PharmaEssentia Corporation: Current Employment. Verstovsek: Gilead: Research Funding; Protagonist Therapeutics: Research Funding; NS Pharma: Research Funding; Incyte Corporation: Consultancy, Research Funding; PharmaEssentia: Research Funding; Ital Pharma: Research Funding; CTI BioPharma: Research Funding; Blueprint Medicines Corp: Research Funding; AstraZeneca: Research Funding; Promedior: Research Funding; Genentech: Research Funding; Celgene: Consultancy, Research Funding; Roche: Research Funding; Novartis: Consultancy, Research Funding; Sierra Oncology: Consultancy, Research Funding; Constellation: Consultancy; Pragmatist: Consultancy.

Deregulation of the cytokine-receptor signaling pathway plays a significant role in tumorigenesis. Such deregulation is frequently caused by alterations in the genes involved in the signaling pathway. At the end of 2013, recurrent somatic mutations in the calreticulin (CALR) gene that encodes a molecular chaperone were identified in a subset of patients with Philadelphia-chromosome negative myeloproliferative neoplasms (MPN). The present review focuses on the role of CALR mutations in the oncogenic transformations observed in MPN. All the CALR mutations were found to generate a + 1 frameshift in the reading frame on exon 9, which encodes the carboxy (C)-terminus end of CALR, and thus conferred a common mutant-specific sequence in all the CALR mutants. The mutant CALR (but not the wild-type) constitutively activates the thrombopoietin (TPO) receptor, myeloproliferative leukemia protein (MPL), even in the absence of TPO to induce cellular transformation. Preferential interaction between the mutant CALR and MPL is achieved by a presumptive conformational change induced by the mutant-specific C-terminus domain, which allows N-domain binding to MPL. Even though mutant CALR is expressed on the cell surface and is secreted out of cells, it only presents autocrine capacity for MPL activation. These findings define a novel molecular mechanism by which the mutant molecular chaperone constitutively activates the cytokine receptor to induce cellular transformation.

High-mobility group AT-hook 2 (HMGA2) is crucial for the self-renewal of fetal hematopoietic stem cells (HSCs) but is downregulated in adult HSCs via repression by MIRlet-7 and the polycomb-recessive complex 2 (PRC2) including EZH2. The HMGA2 messenger RNA (mRNA) level is often elevated in patients with myelofibrosis that exhibits an advanced myeloproliferative neoplasm (MPN) subtype, and deletion of Ezh2 promotes the progression of severe myelofibrosis in JAK2V617F mice with upregulation of several oncogenes such as Hmga2. However, the direct role of HMGA2 in the pathogenesis of MPNs remains unknown. To clarify the impact of HMGA2 on MPNs carrying the driver mutation, we generated ΔHmga2/JAK2V617F mice overexpressing Hmga2 due to deletion of the 3' untranslated region. Compared with JAK2V617F mice, ΔHmga2/JAK2V617F mice exhibited more severe leukocytosis, anemia and splenomegaly, and shortened survival, whereas severity of myelofibrosis was comparable. ΔHmga2/JAK2V617F cells showed a greater repopulating ability that reproduced the severe MPN compared with JAK2V617F cells in serial bone marrow transplants, indicating that Hmga2 promotes MPN progression at the HSC level. Hmga2 also enhanced apoptosis of JAK2V617F erythroblasts that may worsen anemia. Relative to JAK2V617F hematopoietic stem and progenitor cells (HSPCs), over 30% of genes upregulated in ΔHmga2/JAK2V617F HSPCs overlapped with those derepressed by Ezh2 loss in JAK2V617F/Ezh2Δ/Δ HSPCs, suggesting that Hmga2 may facilitate upregulation of Ezh2 targets. Correspondingly, deletion of Hmga2 ameliorated anemia and splenomegaly in JAK2V617F/Ezh2Δ/wild-type mice, and MIRlet-7 suppression and PRC2 mutations correlated with the elevated HMGA2 mRNA levels in patients with MPNs, especially myelofibrosis. These findings suggest the crucial role of HMGA2 in MPN progression.

Somatic mutations in JAK2, MPL, and CALR are found in approximately 80% of patients with essential thrombocythemia (ET), whereas the remaining patients are negative for disease-defining mutations and are defined as triple-negative (TN). Studies have shown that some patients with TN-ET harbor non-canonical mutations in JAK2 and MPL; however, the failure to identify recurrent mutations in most patients has made the pathogenesis of TN-ET ambiguous (Milosevic Feenstra et al. Blood 2016, Cabagnols et al. Blood 2016). In this study, we screened 483 patients suspected as having ET in a single center, performed mutation analysis for JAK2 V617F, CALR exon 9, and MPL exon 10, and centrally reviewed bone marrow specimens. We identified 23 patients with TN-ET based on the WHO 2016 criteria. Sequencing analysis of these patients revealed non-canonical mutations in JAK2 and MPL in 4 cases. Whole exome-sequencing analysis of genomic DNA from peripheral blood and CD3-positive cells from 9 patients revealed that 2 patients harbored somatic mutations in other genes; 7 patients showed no detectable somatic mutation. A STAT5 reporter assay revealed that unlike JAK2 V617F and MPL W515L, all non-canonical mutants of JAK2 or MPL activated STAT5 similar to wild-type proteins, suggesting that these mutations did not drive the disease. Statistical analysis of clinical records revealed that patients with TN-ET were mostly young (median age of 36.0 years), female (18/23, 78.3%), and had neither a history of thrombosis nor progression to secondary myelofibrosis and leukemia, demonstrating the unique characteristics of TN-ET. The presence of clonal hematopoiesis, analyzed using genomic DNA purified from granulocytes of peripheral blood from female patients in a human androgen receptor assay, revealed that only 1 out of 15 patients was clonal. Hypothesizing that TN-ET was reactive thrombocytosis, the concentrations of cytokines promoting platelet production such as thrombopoietin (TPO) and interleukin-6 (IL-6) in the serum were analyzed. However, no significant differences in concentrations were observed among ET with driver mutations, TN-ET, and healthy individuals. We next examined the capacity of hematopoietic stem cells from patients with TN-ET to form megakaryocytic colonies. CD34-positive cells purified from cryopreserved bone marrow cells were cultured in the absence or presence of TPO. CD34-positive cells derived from patients with TN-ET exhibited an equivalent capacity to form megakaryocytic colonies compared to those from patients with ET harboring a driver mutation, even in the absence of TPO (Figure 1). Thus, in TN-ET, megakaryopoiesis may have been induced in a cell-autonomous manner. In 10 patients with TN-ET with available blood count data, no sign of thrombocytosis was observed before ET development, indicating that thrombocytosis was not hereditary but rather occurred via an alternate mechanism, such as aberrations in epigenomic regulation that induced cellular transformation (Ohnishi et al, Cell 2015). Taken together, TN-ET is a distinctive disease entity associated with polyclonal hematopoiesis and paradoxically caused by hematopoietic stem cells harboring a capacity for cell-autonomous megakaryopoiesis. Figure 1 Disclosures Komatsu: Takeda Pharmaceutical Co., Ltd, Novartis Pharma KK, Shire Japan KK: Speakers Bureau; PPMX: Consultancy, Research Funding; Meiji Seika Pharma Co., Ltd.: Patents & Royalties: PCT/JP2020/008434, Research Funding; AbbVie: Other: member of safety assessment committee in M13-834 clinical trial.; Otsuka Pharmaceutical Co., Ltd., Shire Japan KK, Novartis Pharma KK, PharmaEssentia Japan KK, Fuso Pharmaceutical Industries, Ltd., Fujifilm Wako Pure Chemical Corporation, Chugai Pharmaceutical Co., Ltd., Kyowa Hakko Kirin Co., Ltd., Takeda Pharmaceutica: Research Funding; Otsuka Pharmaceutical Co., Ltd., PharmaEssentia Japan KK, AbbVie GK, Celgene KK, Novartis Pharma KK, Shire Japan KK, Japan Tobacco Inc: Consultancy.

Polycythemia vera (PV) is the most common type of Philadelphia-negative myeloproliferative neoplasms (MPNs). PV is a long-term debilitating and life-threatening condition as it is associated with the risk of thrombosis, hemorrhage, and a long-term propensity to develop myelofibrosis and secondary acute myeloid leukemia. Early intervention with disease-modifying treatment that can eradicate the mutated clones is needed to prevent disease progression and transformation. To date, therapeutic options for PV are limited and no cure is available. Most low-risk patients with PV are treated with phlebotomy and low-dose aspirin to manage increased blood viscosity and reduce the risk of vascular events, whereas high-risk patients require cytoreductive treatment. Several cytoreductive agents are available and hydroxyurea (HU) is commonly used as a first-line therapy. Ruxolitinib, a JAK2 inhibitor, is approved as a second-line treatment of PV restricted to patients who are resistant to or intolerant of HU. While interferon alfa agents have reported efficacy in patients with PV, their use has been limited by tolerability concerns. Ropeginterferon alfa-2b (P1101), a long-acting, mono-PEGylated proline interferon, was developed for the treatment of PV. The novel formulation of P1101 improves its pharmacokinetic properties allowing once every 2 weeks administration and offering improved tolerability and convenience. P1101 was evaluated for the treatment of PV in the phase 3 PROUD-PV trial and its extension study CONTINUATION-PV. In CONTINUATION-PV, a significantly higher proportion of patients treated with P1101 achieved complete hematologic response (CHR) with improved disease burden at 36 months compared with patients treated with HU. P1101 has recently been approved by the European Medicines Agency and the Taiwan Food and Drug Administration as monotherapy in adults for the treatment of PV without symptomatic splenomegaly. Here, we describe a phase 2 study to evaluate the safety and efficacy of P1101 in Japanese patients with PV for whom the current standard of treatment is difficult to apply. This is an ongoing phase 2, open-label, multicenter, single-arm study. Eligible patients receive subcutaneous administration of P1101, starting at 100 μg with dose escalation by 50 μg every 2 weeks until stabilization of hematological parameters at the highest tolerated dose. The dose is maintained at the highest dose that can be tolerated and delivers the best disease response. The maximum recommended single dose is 500 μg every 2 weeks. Low-dose aspirin is administered during the 52 weeks of study treatment, unless contraindicated. At weeks 36 and 52, the primary study endpoint, phlebotomy-free CHR, is analyzed. Secondary endpoints include changes in hematocrit, white blood cell count, platelet count, and spleen size from baseline; time requiring no phlebotomy; time to first response; and duration of response maintenance. After completion of 52-weeks of treatment, collection of the long-term follow-up information (blood parameters, molecular and cytogenetic data, safety parameters, and optional bone marrow data) will be continued until the drug becomes commercially available for all patients. Key eligibility criteria include patients diagnosed with PV according to the WHO criteria, a total cumulative HU treatment duration < 3 years at screening, and patients where the current standard therapy is difficult to apply. The study population includes patients across a wide age range (26 to 72 years) with the median age of 54. Patients are 55% female, 48.3% received prior HU therapy, and 93.1% are JAK2 V617F mutation positive. Patients with a documented history of refractoriness to HU, previous use of interferon alfa, or symptomatic splenomegaly are not eligible. Additional baseline characteristics are shown in Table 1. This study addresses an unmet need for patients where standard therapy cannot be applied. The study population includes younger patients who would require treatment, patients who are classified as low risk of thrombosis, but are considered to be candidates for cytoreductive therapy based on disease-related symptoms, and patients who are intolerant to HU. Data from these patients will be used to demonstrate the safety and efficacy of P1101 and help patients for whom the standard of care is difficult to apply. Trial results are anticipated for Q3 2021. NCT04182100. Disclosures Kirito: Novartis Pharma KK: Honoraria; Shire Japan: Honoraria; Pharmaessential Japan: Honoraria. Shimoda:Otsuka Pharmaceutical: Research Funding; Asahi Kasei Medical: Research Funding; Japanese Society of Hematology: Research Funding; The Shinnihon Foundation of Advanced Medical Treatment Research: Research Funding; Pfizer Inc.: Research Funding; Kyowa Hakko Kirin Co., Ltd.: Research Funding; CHUGAI PHARMACEUTICAL CO., LTD.: Research Funding; Merck & Co.: Research Funding; Astellas Pharma: Research Funding; AbbVie Inc.: Research Funding; PharmaEssentia Japan: Research Funding; Perseus Proteomics: Research Funding; Celgene: Honoraria; Shire plc: Honoraria; Bristol-Myers Squibb: Honoraria; Takeda Pharmaceutical Company: Honoraria; Novartis: Honoraria, Research Funding. Komatsu:Otsuka Pharmaceutical Co., Ltd., Shire Japan KK, Novartis Pharma KK, PharmaEssentia Japan KK, Fuso Pharmaceutical Industries, Ltd., Fujifilm Wako Pure Chemical Corporation, Chugai Pharmaceutical Co., Ltd., Kyowa Hakko Kirin Co., Ltd., Takeda Pharmaceutica: Research Funding; Meiji Seika Pharma Co., Ltd.: Patents & Royalties: PCT/JP2020/008434, Research Funding; Takeda Pharmaceutical Co., Ltd, Novartis Pharma KK, Shire Japan KK: Speakers Bureau; AbbVie: Other: member of safety assessment committee in M13-834 clinical trial.; PPMX: Consultancy, Research Funding; Otsuka Pharmaceutical Co., Ltd., PharmaEssentia Japan KK, AbbVie GK, Celgene KK, Novartis Pharma KK, Shire Japan KK, Japan Tobacco Inc: Consultancy.