Glutathione peroxidase 4-regulated neutrophil ferroptosis induces systemic autoimmunity.

The linkage between neutrophil death and the development of autoimmunity has not been thoroughly explored. Here, we show that neutrophils from either lupus-prone mice or patients with systemic lupus erythematosus (SLE) undergo ferroptosis. Mechanistically, autoantibodies and interferon-α present in the serum induce neutrophil ferroptosis through enhanced binding of the transcriptional repressor CREMα to the glutathione peroxidase 4 (Gpx4, the key ferroptosis regulator) promoter, which leads to suppressed expression of Gpx4 and subsequent elevation of lipid-reactive oxygen species. Moreover, the findings that mice with neutrophil-specific Gpx4 haploinsufficiency recapitulate key clinical features of human SLE, including autoantibodies, neutropenia, skin lesions and proteinuria, and that the treatment with a specific ferroptosis inhibitor significantly ameliorates disease severity in lupus-prone mice reveal the role of neutrophil ferroptosis in lupus pathogenesis. Together, our data demonstrate that neutrophil ferroptosis is an important driver of neutropenia in SLE and heavily contributes to disease manifestations.

Genetic defects in severe congenital neutropenia: emerging insights into life and death of human neutrophil granulocytes.

The discovery of genetic defects causing congenital neutropenia has illuminated mechanisms controlling differentiation, circulation, and decay of neutrophil granulocytes. Deficiency of the mitochondrial proteins HAX1 and AK2 cause premature apoptosis of myeloid progenitor cells associated with dissipation of the mitochondrial membrane potential, whereas mutations in ELA2/ELANE and G6PC3 are associated with signs of increased endoplasmic reticulum stress. Mutations in the transcriptional repressor GFI1 and the cytoskeletal regulator WASP also lead to defective neutrophil production. This unexpected diversity of factors suggests that multiple pathways are involved in the pathogenesis of congenital neutropenia.

Atypical chemokine receptor 1 on nucleated erythroid cells regulates hematopoiesis.

Healthy individuals of African ancestry have neutropenia that has been linked with the variant rs2814778(G) of the gene encoding atypical chemokine receptor 1 (ACKR1). This polymorphism selectively abolishes the expression of ACKR1 in erythroid cells, causing a Duffy-negative phenotype. Here we describe an unexpected fundamental role for ACKR1 in hematopoiesis and provide the mechanism that links its absence with neutropenia. Nucleated erythroid cells had high expression of ACKR1, which facilitated their direct contact with hematopoietic stem cells. The absence of erythroid ACKR1 altered mouse hematopoiesis including stem and progenitor cells, which ultimately gave rise to phenotypically distinct neutrophils that readily left the circulation, causing neutropenia. Individuals with a Duffy-negative phenotype developed a distinct profile of neutrophil effector molecules that closely reflected the one observed in the ACKR1-deficient mice. Thus, alternative physiological patterns of hematopoiesis and bone marrow cell outputs depend on the expression of ACKR1 in the erythroid lineage, findings with major implications for the selection advantages that have resulted in the paramount fixation of the ACKR1 rs2814778(G) polymorphism in Africa.

A naturally inspired antibiotic to target multidrug-resistant pathogens.

Gram-negative bacteria are responsible for an increasing number of deaths caused by antibiotic-resistant infections1,2. The bacterial natural product colistin is considered the last line of defence against a number of Gram-negative pathogens. The recent global spread of the plasmid-borne mobilized colistin-resistance gene mcr-1 (phosphoethanolamine transferase) threatens the usefulness of colistin3. Bacteria-derived antibiotics often appear in nature as collections of similar structures that are encoded by evolutionarily related biosynthetic gene clusters. This structural diversity is, at least in part, expected to be a response to the development of natural resistance, which often mechanistically mimics clinical resistance. Here we propose that a solution to mcr-1-mediated resistance might have evolved among naturally occurring colistin congeners. Bioinformatic analysis of sequenced bacterial genomes identified a biosynthetic gene cluster that was predicted to encode a structurally divergent colistin congener. Chemical synthesis of this structure produced macolacin, which is active against Gram-negative pathogens expressing mcr-1 and intrinsically resistant pathogens with chromosomally encoded phosphoethanolamine transferase genes. These Gram-negative bacteria include extensively drug-resistant Acinetobacter baumannii and intrinsically colistin-resistant Neisseria gonorrhoeae, which, owing to a lack of effective treatment options, are considered among the highest level threat pathogens4. In a mouse neutropenic infection model, a biphenyl analogue of macolacin proved to be effective against extensively drug-resistant A. baumannii with colistin-resistance, thus providing a naturally inspired and easily produced therapeutic lead for overcoming colistin-resistant pathogens.

Upadacitinib Induction and Maintenance Therapy for Crohn's Disease.

BACKGROUND: Upadacitinib, an oral selective Janus kinase (JAK) inhibitor, is under investigation for the treatment of Crohn's disease. METHODS: In two phase 3 induction trials (U-EXCEL and U-EXCEED), we randomly assigned patients with moderate-to-severe Crohn's disease to receive 45 mg of upadacitinib or placebo (2:1 ratio) once daily for 12 weeks. Patients who had a clinical response to upadacitinib induction therapy were randomly assigned in the U-ENDURE maintenance trial to receive 15 mg of upadacitinib, 30 mg of upadacitinib, or placebo (1:1:1 ratio) once daily for 52 weeks. The primary end points for induction (week 12) and maintenance (week 52) were clinical remission (defined as a Crohn's Disease Activity Index score of <150 [range, 0 to 600, with higher scores indicating more severe disease activity]) and endoscopic response (defined as a decrease in the Simple Endoscopic Score for Crohn's Disease [SES-CD; range, 0 to 56, with higher scores indicating more severe disease] of >50% from baseline of the induction trial [or for patients with an SES-CD of 4 at baseline, a decrease of ≥2 points from baseline]). RESULTS: A total of 526 patients underwent randomization in U-EXCEL, 495 in U-EXCEED, and 502 in U-ENDURE. A significantly higher percentage of patients who received 45-mg upadacitinib than those who received placebo had clinical remission (in U-EXCEL, 49.5% vs. 29.1%; in U-EXCEED, 38.9% vs. 21.1%) and an endoscopic response (in U-EXCEL, 45.5% vs. 13.1%; in U-EXCEED, 34.6% vs. 3.5%) (P<0.001 for all comparisons). At week 52 in U-ENDURE, a higher percentage of patients had clinical remission with 15-mg upadacitinib (37.3%) or 30-mg upadacitinib (47.6%) than with placebo (15.1%), and a higher percentage had an endoscopic response with 15-mg upadacitinib (27.6%) or 30-mg upadacitinib (40.1%) than with placebo (7.3%) (P<0.001 for all comparisons). Herpes zoster infections occurred more frequently in the 45-mg and 30-mg upadacitinib groups than in the respective placebo groups, and hepatic disorders and neutropenia were more frequent in the 30-mg upadacitinib group than in the other maintenance groups. Gastrointestinal perforations developed in 4 patients who received 45-mg upadacitinib and in 1 patient each who received 30-mg or 15-mg upadacitinib. CONCLUSIONS: Upadacitinib induction and maintenance treatment was superior to placebo in patients with moderate-to-severe Crohn's disease. (Funded by AbbVie; U-EXCEL, U-EXCEED, and U-ENDURE ClinicalTrials.gov numbers, NCT03345849, NCT03345836, and NCT03345823.).

Pirtobrutinib after a Covalent BTK Inhibitor in Chronic Lymphocytic Leukemia.

BACKGROUND: Patients with chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL) have poor outcomes after the failure of covalent Bruton's tyrosine kinase (BTK) inhibitor treatment, and new therapeutic options are needed. Pirtobrutinib, a highly selective, noncovalent (reversible) BTK inhibitor, was designed to reestablish BTK inhibition. METHODS: We conducted a phase 1-2 trial in which patients with relapsed or refractory B-cell cancers received pirtobrutinib. Here, we report efficacy results among patients with CLL or SLL who had previously received a BTK inhibitor as well as safety results among all the patients with CLL or SLL. The primary end point was an overall response (partial response or better) as assessed by independent review. Secondary end points included progression-free survival and safety. RESULTS: A total of 317 patients with CLL or SLL received pirtobrutinib, including 247 who had previously received a BTK inhibitor. Among these 247 patients, the median number of previous lines of therapy was 3 (range, 1 to 11), and 100 patients (40.5%) had also received a B-cell lymphoma 2 (BCL2) inhibitor such as venetoclax. The percentage of patients with an overall response to pirtobrutinib was 73.3% (95% confidence interval [CI], 67.3 to 78.7), and the percentage was 82.2% (95% CI, 76.8 to 86.7) when partial response with lymphocytosis was included. The median progression-free survival was 19.6 months (95% CI, 16.9 to 22.1). Among all 317 patients with CLL or SLL who received pirtobrutinib, the most common adverse events were infections (in 71.0%), bleeding (in 42.6%), and neutropenia (in 32.5%). At a median duration of treatment of 16.5 months (range, 0.2 to 39.9), some adverse events that are typically associated with BTK inhibitors occurred relatively infrequently, including hypertension (in 14.2% of patients), atrial fibrillation or flutter (in 3.8%), and major hemorrhage (in 2.2%). Only 9 of 317 patients (2.8%) discontinued pirtobrutinib owing to a treatment-related adverse event. CONCLUSIONS: In this trial, pirtobrutinib showed efficacy in patients with heavily pretreated CLL or SLL who had received a covalent BTK inhibitor. The most common adverse events were infections, bleeding, and neutropenia. (Funded by Loxo Oncology; BRUIN ClinicalTrials.gov number, NCT03740529.).

Mezigdomide plus Dexamethasone in Relapsed and Refractory Multiple Myeloma.

BACKGROUND: Despite recent progress, multiple myeloma remains incurable. Mezigdomide is a novel cereblon E3 ubiquitin ligase modulator with potent antiproliferative and tumoricidal activity in preclinical models of multiple myeloma, including those resistant to lenalidomide and pomalidomide. METHODS: In this phase 1-2 study, we administered oral mezigdomide in combination with dexamethasone to patients with relapsed and refractory myeloma. The primary objectives of phase 1 (dose-escalation cohort) were to assess safety and pharmacokinetics and to identify the dose and schedule for phase 2. In phase 2 (dose-expansion cohort), objectives included the assessment of the overall response (partial response or better), safety, and efficacy of mezigdomide plus dexamethasone at the dose and schedule determined in phase 1. RESULTS: In phase 1, a total of 77 patients were enrolled in the study. The most common dose-limiting toxic effects were neutropenia and febrile neutropenia. On the basis of the phase 1 findings, investigators determined the recommended phase 2 dose of mezigdomide to be 1.0 mg, given once daily in combination with dexamethasone for 21 days, followed by 7 days off, in each 28-day cycle. In phase 2, a total of 101 patients received the dose identified in phase 1 in the same schedule. All patients in the dose-expansion cohort had triple-class-refractory multiple myeloma, 30 patients (30%) had received previous anti-B-cell maturation antigen (anti-BCMA) therapy, and 40 (40%) had plasmacytomas. The most common adverse events, almost all of which proved to be reversible, included neutropenia (in 77% of the patients) and infection (in 65%; grade 3, 29%; grade 4, 6%). No unexpected toxic effects were encountered. An overall response occurred in 41% of the patients (95% confidence interval [CI], 31 to 51), the median duration of response was 7.6 months (95% CI, 5.4 to 9.5; data not mature), and the median progression-free survival was 4.4 months (95% CI, 3.0 to 5.5), with a median follow-up of 7.5 months (range, 0.5 to 21.9). CONCLUSIONS: The all-oral combination of mezigdomide plus dexamethasone showed promising efficacy in patients with heavily pretreated multiple myeloma, with treatment-related adverse events consisting mainly of myelotoxic effects. (Funded by Celgene, a Bristol-Myers Squibb Company; CC-92480-MM-001 ClinicalTrials.gov number, NCT03374085; EudraCT number, 2017-001236-19.).

Two-year follow-up of lisocabtagene maraleucel in relapsed or refractory large B-cell lymphoma in TRANSCEND NHL 001.

ABSTRACT: Lisocabtagene maraleucel (liso-cel) demonstrated significant efficacy with a manageable safety profile as third-line or later treatment for patients with relapsed or refractory (R/R) large B-cell lymphoma (LBCL) in the TRANSCEND NHL 001 study. Primary end points were adverse events (AEs), dose-limiting toxicities, and objective response rate (ORR) per independent review committee. Key secondary end points were complete response (CR) rate, duration of response (DOR), progression-free survival (PFS), and overall survival (OS). After 2-year follow-up, patients could enroll in a separate study assessing long-term (≤15 years) safety and OS. Liso-cel-treated patients (N = 270) had a median age of 63 years (range, 18-86 years) and a median of 3 prior lines (range, 1-8) of systemic therapy, and 181 of them (67%) had chemotherapy-refractory LBCL. Median follow-up was 19.9 months. In efficacy-evaluable patients (N = 257), the ORR was 73% and CR rate was 53%. The median (95% confidence interval) DOR, PFS, and OS were 23.1 (8.6 to not reached), 6.8 (3.3-12.7), and 27.3 months (16.2-45.6), respectively. Estimated 2-year DOR, PFS, and OS rates were 49.5%, 40.6%, and 50.5%, respectively. In the 90-day treatment-emergent period (N = 270), grade 3 to 4 cytokine release syndrome and neurological events occurred in 2% and 10% of patients, respectively. The most common grade ≥3 AEs in treatment-emergent and posttreatment-emergent periods, respectively, were neutropenia (60% and 7%) and anemia (37% and 6%). Liso-cel demonstrated durable remissions and a manageable safety profile with no new safety signals during the 2-year follow-up in patients with R/R LBCL. These trials were registered at www.ClinicalTrials.gov as #NCT02631044 and #NCT03435796.

Mouse models of neutropenia reveal progenitor-stage-specific defects.

Advances in genetics and sequencing have identified a plethora of disease-associated and disease-causing genetic alterations. To determine causality between genetics and disease, accurate models for molecular dissection are required; however, the rapid expansion of transcriptional populations identified through single-cell analyses presents a major challenge for accurate comparisons between mutant and wild-type cells. Here we generate mouse models of human severe congenital neutropenia (SCN) using patient-derived mutations in the GFI1 transcription factor. To determine the effects of SCN mutations, we generated single-cell references for granulopoietic genomic states with linked epitopes1, aligned mutant cells to their wild-type equivalents and identified differentially expressed genes and epigenetic loci. We find that GFI1-target genes are altered sequentially, as cells go through successive states of differentiation. These insights facilitated the genetic rescue of granulocytic specification but not post-commitment defects in innate immune effector function, and underscore the importance of evaluating the effects of mutations and therapy within each relevant cell state.

Overall Survival with Ribociclib plus Letrozole in Advanced Breast Cancer.

BACKGROUND: In a previous analysis of this phase 3 trial, first-line ribociclib plus letrozole resulted in significantly longer progression-free survival than letrozole alone among postmenopausal patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer. Whether overall survival would also be longer with ribociclib was not known. METHODS: Here we report the results of the protocol-specified final analysis of overall survival, a key secondary end point. Patients were randomly assigned in a 1:1 ratio to receive either ribociclib or placebo in combination with letrozole. Overall survival was assessed with the use of a stratified log-rank test and summarized with the use of Kaplan-Meier methods after 400 deaths had occurred. A hierarchical testing strategy was used for the analysis of progression-free survival and overall survival to ensure the validity of the findings. RESULTS: After a median follow-up of 6.6 years, 181 deaths had occurred among 334 patients (54.2%) in the ribociclib group and 219 among 334 (65.6%) in the placebo group. Ribociclib plus letrozole showed a significant overall survival benefit as compared with placebo plus letrozole. Median overall survival was 63.9 months (95% confidence interval [CI], 52.4 to 71.0) with ribociclib plus letrozole and 51.4 months (95% CI, 47.2 to 59.7) with placebo plus letrozole (hazard ratio for death, 0.76; 95% CI, 0.63 to 0.93; two-sided P = 0.008). No new safety signals were observed. CONCLUSIONS: First-line therapy with ribociclib plus letrozole showed a significant overall survival benefit as compared with placebo plus letrozole in patients with HR-positive, HER2-negative advanced breast cancer. Median overall survival was more than 12 months longer with ribociclib than with placebo. (Funded by Novartis; MONALEESA-2 ClinicalTrials.gov number, NCT01958021.).

Darolutamide and Survival in Metastatic, Hormone-Sensitive Prostate Cancer.

BACKGROUND: Darolutamide is a potent androgen-receptor inhibitor that has been associated with increased overall survival among patients with nonmetastatic, castration-resistant prostate cancer. Whether a combination of darolutamide, androgen-deprivation therapy, and docetaxel would increase survival among patients with metastatic, hormone-sensitive prostate cancer is unknown. METHODS: In this international, phase 3 trial, we randomly assigned patients with metastatic, hormone-sensitive prostate cancer in a 1:1 ratio to receive darolutamide (at a dose of 600 mg [two 300-mg tablets] twice daily) or matching placebo, both in combination with androgen-deprivation therapy and docetaxel. The primary end point was overall survival. RESULTS: The primary analysis involved 1306 patients (651 in the darolutamide group and 655 in the placebo group); 86.1% of the patients had disease that was metastatic at the time of the initial diagnosis. At the data cutoff date for the primary analysis (October 25, 2021), the risk of death was significantly lower, by 32.5%, in the darolutamide group than in the placebo group (hazard ratio 0.68; 95% confidence interval, 0.57 to 0.80; P<0.001). Darolutamide was also associated with consistent benefits with respect to the secondary end points and prespecified subgroups. Adverse events were similar in the two groups, and the incidences of the most common adverse events (occurring in ≥10% of the patients) were highest during the overlapping docetaxel treatment period in both groups. The frequency of grade 3 or 4 adverse events was 66.1% in the darolutamide group and 63.5% in the placebo group; neutropenia was the most common grade 3 or 4 adverse event (in 33.7% and 34.2%, respectively). CONCLUSIONS: In this trial involving patients with metastatic, hormone-sensitive prostate cancer, overall survival was significantly longer with the combination of darolutamide, androgen-deprivation therapy, and docetaxel than with placebo plus androgen-deprivation therapy and docetaxel, and the addition of darolutamide led to improvement in key secondary end points. The frequency of adverse events was similar in the two groups. (Funded by Bayer and Orion Pharma; ARASENS ClinicalTrials.gov number, NCT02799602.).

Trial of Deferiprone in Parkinson's Disease.

BACKGROUND: Iron content is increased in the substantia nigra of persons with Parkinson's disease and may contribute to the pathophysiology of the disorder. Early research suggests that the iron chelator deferiprone can reduce nigrostriatal iron content in persons with Parkinson's disease, but its effects on disease progression are unclear. METHODS: We conducted a multicenter, phase 2, randomized, double-blind trial involving participants with newly diagnosed Parkinson's disease who had never received levodopa. Participants were assigned (in a 1:1 ratio) to receive oral deferiprone at a dose of 15 mg per kilogram of body weight twice daily or matched placebo for 36 weeks. Dopaminergic therapy was withheld unless deemed necessary for symptom control. The primary outcome was the change in the total score on the Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS; range, 0 to 260, with higher scores indicating more severe impairment) at 36 weeks. Secondary and exploratory clinical outcomes at up to 40 weeks included measures of motor and nonmotor disability. Brain iron content measured with the use of magnetic resonance imaging was also an exploratory outcome. RESULTS: A total of 372 participants were enrolled; 186 were assigned to receive deferiprone and 186 to receive placebo. Progression of symptoms led to the initiation of dopaminergic therapy in 22.0% of the participants in the deferiprone group and 2.7% of those in the placebo group. The mean MDS-UPDRS total score at baseline was 34.3 in the deferiprone group and 33.2 in the placebo group and increased (worsened) by 15.6 points and 6.3 points, respectively (difference, 9.3 points; 95% confidence interval, 6.3 to 12.2; P<0.001). Nigrostriatal iron content decreased more in the deferiprone group than in the placebo group. The main serious adverse events with deferiprone were agranulocytosis in 2 participants and neutropenia in 3 participants. CONCLUSIONS: In participants with early Parkinson's disease who had never received levodopa and in whom treatment with dopaminergic medications was not planned, deferiprone was associated with worse scores in measures of parkinsonism than those with placebo over a period of 36 weeks. (Funded by the European Union Horizon 2020 program; FAIRPARK-II ClinicalTrials.gov number, NCT02655315.).

How I manage inpatient consultations for quantitative neutrophil abnormalities in adults.

Neutrophilia and neutropenia commonly lead to inpatient hematology consultation. Quantitative neutrophil abnormalities have a broad differential and include diagnoses that are important to recognize because they may be associated with increased mortality. Neutrophilia can reflect etiologies such as infection, medications, inflammation, splenectomy, and congenital disorders. Neutropenia can arise from infection, medications, autoimmune destruction, sequestration, nutritional deficiency, malignancy, and congenital neutropenia syndromes. In the evaluation of all abnormalities of neutrophil number, the timing of the change, and the patient's historical neutrophil count are crucial.

Tγδ LGLL identifies a subset with more symptomatic disease: analysis of an international cohort of 137 patients.

Tγδ large granular lymphocyte leukemia (LGLL) is a rare variant of T-cell LGLL (T-LGLL) that has been less investigated as compared with the more frequent Tαß LGLL, particularly in terms of frequency of STAT3 and STAT5b mutations. In this study, we characterized the clinical and biological features of 137 patients affected by Tγδ LGLL; data were retrospectively collected from 1997 to 2020 at 8 referral centers. Neutropenia and anemia were the most relevant clinical features, being present in 54.2% and 49.6% of cases, respectively, including severe neutropenia and anemia in ∼20% of cases each. Among the various treatments, cyclosporine A was shown to provide the best response rates. DNA samples of 97 and 94 cases were available for STAT3 and STAT5b mutation analysis, with 38.1% and 4.2% of cases being mutated, respectively. Clinical and biological features of our series of Tγδ cases were also compared with a recently published Tαß cohort including 129 cases. Though no differences in STAT3 and STAT5b mutational frequency were found, Tγδ cases more frequently presented with neutropenia (P = .0161), anemia (P < .0001), severe anemia (P = .0065), and thrombocytopenia (P = .0187). Moreover, Vδ2- cases displayed higher frequency of symptomatic disease. Overall, Tγδ cases displayed reduced survival with respect to Tαß cases (P = .0017). Although there was no difference in STAT3 mutation frequency, our results showed that Tγδ LGLL represents a subset of T-LGLL characterized by more frequent symptoms and reduced survival as compared with Tαß LGLL.

Effective treatment with the selective cytokine inhibitor BNZ-1 reveals the cytokine dependency of T-LGL leukemia.

T-cell large granular lymphocytic leukemia (T-LGLL) is a clonal proliferation of cytotoxic T lymphocytes that can result in severe neutropenia, anemia, and bone marrow failure. Strong evidence from patients and mouse models demonstrate the critical role of interleukin-15 (IL-15) in T-LGLL pathogenesis. BNZ-1 is a pegylated peptide that selectively inhibits the binding of IL-15 and other γc cytokines to their cellular receptor complex, which has demonstrated efficacy in ex vivo T-LGLL cells and transgenic mice in preclinical studies. We conducted a phase 1/2 trial of BNZ-1 in patients with T-LGLL who had hematocytopenias (anemia or neutropenia) and required therapy. Clinical responses were assessed using hematologic parameters (improvement in hematocytopenias) based on response criteria from the Eastern Cooperative Oncology Group 5998 T-LGLL trial. BNZ-1 demonstrated clinical partial responses in 20% of patients with T-LGLL with minimal toxicity and the maximum tolerated dose was not reached. Furthermore, T-LGL leukemic cells showed significantly increased apoptosis in response to BNZ-1 treatment as early as day 2, including in clinical nonresponders, with changes that remained statistically different from baseline throughout treatment (P < .005). We report first-in-human proof that T-LGL leukemic cells are dependent on IL-15 and that intervention with IL-15 inhibition with BNZ-1 in patients with T-LGLL shows therapeutic effects, which carries important implications for the understanding of the pathogenesis of this disease. This trial was registered at www.clinicaltrials.gov as #NCT03239392.

An open-label, single-arm phase 2 trial of valemetostat for relapsed or refractory adult T-cell leukemia/lymphoma.

Adult T-cell leukemia/lymphoma (ATL) is an aggressive non-Hodgkin lymphoma with poor prognosis and few treatment options for patients with relapsed, recurrent, or refractory disease. We evaluated the efficacy and safety of valemetostat, a potent enhancer of zeste homolog 2 (EZH2) and EZH1 inhibitor, in treating relapsed or refractory (R/R) ATL. This multicenter phase 2 trial enrolled patients with R/R aggressive ATL (acute, lymphoma, unfavorable chronic type). Patients received valemetostat 200 mg/day orally until progressive disease or unacceptable toxicity. The primary end point was overall response rate (ORR) centrally assessed by an independent efficacy assessment committee (IEAC). Secondary end points included best response in disease compartments, duration of response (DOR), pharmacokinetics, and safety. Twenty-five patients (median age, 69.0 years) with a median of 3 prior lines of therapy were enrolled; 24 had prior mogamulizumab treatment. The primary end point was met with a centrally reviewed ORR of 48.0% (90% confidence interval [CI], 30.5-65.9), including 5 complete and 7 partial remissions. Patients pretreated with mogamulizumab had an ORR of 45.8% (4 complete and 7 partial remissions). IEAC-assessed median DOR was not reached (NR) (95% CI, 1.87 to NR; months). Treatment-emergent adverse events (TEAEs) were manageable. TEAEs that occurred in ≥20% of patients included thrombocytopenia, anemia, alopecia, dysgeusia, neutropenia, lymphopenia, leukopenia, decreased appetite, and pyrexia. Grade ≥3 TEAEs included thrombocytopenia, anemia, lymphopenia, leukopenia, and neutropenia. Valemetostat demonstrated promising efficacy and tolerability in heavily pretreated patients, warranting further investigation in treating R/R ATL. This trial was registered at www.clinicaltrials.gov as #NCT04102150.

Severe CD8+ T Lymphopenia in WHIM Syndrome Caused by Selective Sequestration in Primary Immune Organs.

Warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome is an ultra-rare combined primary immunodeficiency disease caused by heterozygous gain-of-function mutations in the chemokine receptor CXCR4. WHIM patients typically present with recurrent acute infections associated with myelokathexis (severe neutropenia due to bone marrow retention of mature neutrophils). Severe lymphopenia is also common, but the only associated chronic opportunistic pathogen is human papillomavirus and mechanisms are not clearly defined. In this study, we show that WHIM mutations cause more severe CD8 than CD4 lymphopenia in WHIM patients and WHIM model mice. Mechanistic studies in mice revealed selective and WHIM allele dose-dependent accumulation of mature CD8 single-positive cells in thymus in a cell-intrinsic manner due to prolonged intrathymic residence, associated with increased CD8 single-positive thymocyte chemotactic responses in vitro toward the CXCR4 ligand CXCL12. In addition, mature WHIM CD8+ T cells preferentially home to and are retained in the bone marrow in mice in a cell-intrinsic manner. Administration of the specific CXCR4 antagonist AMD3100 (plerixafor) in mice rapidly and transiently corrected T cell lymphopenia and the CD4/CD8 ratio. After lymphocytic choriomeningitis virus infection, we found no difference in memory CD8+ T cell differentiation or viral load between wild-type and WHIM model mice. Thus, lymphopenia in WHIM syndrome may involve severe CXCR4-dependent CD8+ T cell deficiency resulting in part from sequestration in the primary lymphoid organs, thymus, and bone marrow.

CRISPR-Cas9n-mediated ELANE promoter editing for gene therapy of severe congenital neutropenia.

Severe congenital neutropenia (CN) is an inherited pre-leukemia bone marrow failure syndrome commonly caused by autosomal-dominant ELANE mutations (ELANE-CN). ELANE-CN patients are treated with daily injections of recombinant human granulocyte colony-stimulating factor (rhG-CSF). However, some patients do not respond to rhG-CSF, and approximately 15% of ELANE-CN patients develop myelodysplasia or acute myeloid leukemia. Here, we report the development of a curative therapy for ELANE-CN through inhibition of ELANE mRNA expression by introducing two single-strand DNA breaks at the opposing DNA strands of the ELANE promoter TATA box using CRISPR-Cas9D10A nickases-termed MILESTONE. This editing effectively restored defective neutrophil differentiation of ELANE-CN CD34+ hematopoietic stem and progenitor cells (HSPCs) in vitro and in vivo, without affecting the functions of the edited neutrophils. CRISPResso analysis of the edited ELANE-CN CD34+ HSPCs revealed on-target efficiencies of over 90%. Simultaneously, GUIDE-seq, CAST-Seq, and rhAmpSeq indicated a safe off-target profile with no off-target sites or chromosomal translocations. Taken together, ex vivo gene editing of ELANE-CN HSPCs using MILESTONE in the setting of autologous stem cell transplantation could be a universal, safe, and efficient gene therapy approach for ELANE-CN patients.

G-CSF, the guardian of granulopoiesis.

A considerable amount of continuous proliferation and differentiation is required to produce daily a billion new neutrophils in an adult human. Of the few cytokines and factors known to control neutrophil production, G-CSF is the guardian of granulopoiesis. G-CSF/CSF3R signaling involves the recruitment of non-receptor protein tyrosine kinases and their dependent signaling pathways of serine/threonine kinases, tyrosine phosphatases, and lipid second messengers. These pathways converge to activate the families of STAT and C/EBP transcription factors. CSF3R mutations are associated with human disorders of neutrophil production, including severe congenital neutropenia, neutrophilia, and myeloid malignancies. More than three decades after their identification, cloning, and characterization of G-CSF and G-CSF receptor, fundamental questions remain about their physiology.

Reactive granulopoiesis depends on T-cell production of IL-17A and neutropenia-associated alteration of gut microbiota.

Granulopoiesis in the bone marrow adjusts cellular output as demand for neutrophils changes. Reactive granulopoiesis is induced by profound neutropenia, but its mechanism remains to be clarified. We herein explored its mechanisms using mouse models of syngeneic hematopoietic stem cell transplantation (SCT) and 5-fluorouracil-induced neutropenia. After SCT, T cell production of IL-17A was up-regulated. Neutrophil recovery was significantly delayed in IL-17A-deficient or T cell-deficient RAG1-/- mice, and adoptive transfer of wild-type (WT) T cells facilitated neutrophil engraftment. Gut decontamination with oral antibiotics suppressed T cell production of IL-17A and impaired neutrophil recovery. Transplantation of fecal microbiota collected from neutropenic, not naive, mice promoted neutrophil recovery in these mice, suggesting that neutropenia-associated microbiota had a potential to stimulate reactive granulopoiesis. Our study uncovered a cross talk between gut microbiota and neutropenia after SCT and chemotherapy.