Interplay between α-thalassemia and ß-hemoglobinopathies: Translating genotype-phenotype relationships into therapies.

α-Thalassemia represents one of the most important genetic modulators of ß-hemoglobinopathies. During this last decade, the ongoing interest in characterizing genotype-phenotype relationships has yielded incredible insights into α-globin gene regulation and its impact on ß-hemoglobinopathies. In this review, we provide a holistic update on α-globin gene expression stemming from DNA to RNA to protein, as well as epigenetic mechanisms that can impact gene expression and potentially influence phenotypic outcomes. Here, we highlight defined α-globin targeted strategies and rationalize the use of distinct molecular targets based on the restoration of balanced α/ß-like globin chain synthesis. Considering the therapies that either increase ß-globin synthesis or reactivate γ-globin gene expression, the modulation of α-globin chains as a disease modifier for ß-hemoglobinopathies still remains largely uncharted in clinical studies.

Low mortality in vaccinated immunocompromised haematology patients infected with SARS-CoV-2.

Coronavirus disease 2019 (COVID-19) infection in patients with haematological neoplasms has been associated with increased mortality; however, many studies in this patient group were reported early in the pandemic. The authors evaluated outcomes of COVID-19 infection in patients with haematological conditions following widespread vaccination, newer viral variants and increasingly effective antiviral therapies. A 4% mortality rate was found and contemporary risk factors for hospitalisation including older age, nonvaccination or partial COVID-19 vaccination status and infection with non-Omicron strain were identified.

Evaluation of multiple myeloma measurable residual disease by high sensitivity flow cytometry: An international harmonized approach for data analysis.

BACKGROUND: Multiple myeloma (MM) measurable residual disease (MRD) evaluated by flow cytometry is a surrogate for progression-free and overall survival in clinical trials. However, analysis and reporting between centers lack uniformity. We designed and evaluated a consensus protocol for MM MRD analysis to reduce inter-laboratory variation in MM MRD reporting. METHODS: Seventeen participants from 13 countries performed blinded analysis of the same eight de-identified flow cytometry files from patients with/without MRD using their own method (Stage 1). A consensus gating protocol was then designed following survey and discussions, and the data re-analyzed for MRD and other bone marrow cells (Stage 2). Inter-laboratory variation using the consensus strategy was reassessed for another 10 cases and compared with earlier results (Stage 3). RESULTS: In Stage 1, participants agreed on MRD+/MRD- status 89% and 68% of the time respectively. Inter-observer variation was high for total numbers of analyzed cells, total and normal plasma cells (PCs), limit of detection, lower limit of quantification, and enumeration of cell populations that determine sample adequacy. The identification of abnormal PCs remained relatively consistent. By consensus method, average agreement on MRD- status improved to 74%. Better consistency enumerating all parameters among operators resulted in near-unanimous agreement on sample adequacy. CONCLUSION: Uniform flow cytometry data analysis substantially reduced inter-laboratory variation in reporting multiple components of the MM MRD assay. Adoption of a harmonized approach would meet an important need for conformity in reporting MM MRD for clinical trials, and wider acceptance of MM MRD as a surrogate clinical endpoint.

Correlation between a 10-color flow cytometric measurable residual disease (MRD) analysis and molecular MRD in adult B-acute lymphoblastic leukemia.

BACKGROUND: Measurable residual disease (MRD) monitoring in acute lymphoblastic leukemia (ALL) is an important predictive factor for patient outcome and treatment intensification. Molecular monitoring, particularly with quantitative polymerase chain reaction (qPCR) to measure immunoglobin heavy or kappa chain (Ig) or T-cell receptor (TCR) gene rearrangements, offers high sensitivity but accessibility is limited by expertise, cost, and turnaround time. Flow cytometric assays are cheaper and more widely available, and sensitivity is improved with multi-parameter flow cytometry at eight or more colors. METHODS: We developed a 10-color single tube flow cytometry assay. Samples were subject to bulk ammonium chloride lysis to maximize cell yields with a target of 1 × 106 events. Once normal maturation patterns were established, patient samples were analyzed in parallel to standard molecular monitoring. RESULTS: Flow cytometry was performed on 114 samples. An informative immunophenotype was identifiable in all 22 patients who had a diagnostic sample. MRD analysis was performed on 87 samples. The median lower limits of detection and quantification were 0.004% (range 0.0005%-0.028%) and 0.01% (range 0.001%-0.07%) respectively. Sixty-five samples had concurrent molecular MRD testing, with good correlation (r = 0.83, p < 0.001). Results were concordant in 52 samples, and discordant in 13 samples, including one case where impending relapse was detected by flow cytometry but not Ig/TCR qPCR. CONCLUSIONS: Our 10-color flow cytometric MRD assay provided adequate sensitivity and good correlation with molecular assays. This technique offers rapid and affordable testing in B-ALL patients, including cases where a suitable molecular assay cannot be developed or has reduced sensitivity.

Consensus guidelines for the diagnosis and management of cryptococcosis and rare yeast infections in the haematology/oncology setting, 2021.

Cryptococcosis caused by the Cryptococcus neoformans-Cryptococcus gattii complex is an important opportunistic infection in people with immunodeficiency, including in the haematology/oncology setting. This may manifest clinically as cryptococcal meningitis or pulmonary cryptococcosis, or be detected incidentally by cryptococcal antigenemia, a positive sputum culture or radiological imaging. Non-Candida, non-Cryptococcus spp. rare yeast fungaemia are increasingly common in this population. These consensus guidelines aim to provide clinicians working in the Australian and New Zealand haematology/oncology setting with clear guiding principles and practical recommendations for the management of cryptococcosis, while also highlighting important and emerging rare yeast infections and their recommended management.

SLN124, a GalNac-siRNA targeting transmembrane serine protease 6, in combination with deferiprone therapy reduces ineffective erythropoiesis and hepatic iron-overload in a mouse model of ß-thalassaemia.

Beta-thalassaemia is an inherited blood disorder characterised by ineffective erythropoiesis and anaemia. Consequently, hepcidin expression is reduced resulting in increased iron absorption and primary iron overload. Hepcidin is under the negative control of transmembrane serine protease 6 (TMPRSS6) via cleavage of haemojuvelin (HJV), a co-receptor for the bone morphogenetic protein (BMP)-mothers against decapentaplegic homologue (SMAD) signalling pathway. Considering the central role of the TMPRSS6/HJV/hepcidin axis in iron homeostasis, the inhibition of TMPRSS6 expression represents a promising therapeutic strategy to increase hepcidin production and ameliorate anaemia and iron overload in ß-thalassaemia. In the present study, we investigated a small interfering RNA (siRNA) conjugate optimised for hepatic targeting of Tmprss6 (SLN124) in ß-thalassaemia mice (Hbbth3/+ ). Two subcutaneous injections of SLN124 (3 mg/kg) were sufficient to normalise hepcidin expression and reduce anaemia. We also observed a significant improvement in erythroid maturation, which was associated with a significant reduction in splenomegaly. Treatment with the iron chelator, deferiprone (DFP), did not impact any of the erythroid parameters. However, the combination of SLN124 with DFP was more effective in reducing hepatic iron overload than either treatment alone. Collectively, we show that the combination therapy can ameliorate several disease symptoms associated with chronic anaemia and iron overload, and therefore represents a promising pharmacological modality for the treatment of ß-thalassaemia and related disorders.

Coordinated ß-globin expression and α2-globin reduction in a multiplex lentiviral gene therapy vector for ß-thalassemia.

A primary challenge in lentiviral gene therapy of ß-hemoglobinopathies is to maintain low vector copy numbers to avoid genotoxicity while being reliably therapeutic for all genotypes. We designed a high-titer lentiviral vector, LVß-shα2, that allows coordinated expression of the therapeutic ßA-T87Q-globin gene and of an intron-embedded miR-30-based short hairpin RNA (shRNA) selectively targeting the α2-globin mRNA. Our approach was guided by the knowledge that moderate reduction of α-globin chain synthesis ameliorates disease severity in ß-thalassemia. We demonstrate that LVß-shα2 reduces α2-globin mRNA expression in erythroid cells while keeping α1-globin mRNA levels unchanged and ßA-T87Q-globin gene expression identical to the parent vector. Compared with the first ßA-T87Q-globin lentiviral vector that has received conditional marketing authorization, BB305, LVß-shα2 shows 1.7-fold greater potency to improve α/ß ratios. It may thus result in greater therapeutic efficacy and reliability for the most severe types of ß-thalassemia and provide an improved benefit/risk ratio regardless of the ß-thalassemia genotype.

Excellent outcomes of transformed lymphomas in the rituximab era without autologous stem cell transplantation: an Australian single-centre experience.

BACKGROUND: Histologic transformation (HT) is an important event with adverse prognosis in the natural history of indolent lymphomas. There are minimal data on HT in the Australian setting. AIMS: To characterise patients with biopsy-proven HT and their outcomes identified at a tertiary Australian Hospital. METHODS: All patients with biopsy-proven HT during a 15-year period (2002-2017) were included. Clinico-pathological data were systematically collected from review of patient records. Survival estimates were assessed using the Kaplan-Meier method and compared using the log-rank test. Associations between variables and clinical outcomes were evaluated using Cox's proportional hazards model. RESULTS: A cohort of 45 patients was identified with a median age of 66 years and the majority (59%) having high-risk disease (Revised-International Prognostic Index score ≥3). R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisolone) induction was used in 69%, with an overall response rate of 82% (complete response (CR), 75%). Sixty-one percent of these induction responders received consolidation, with autologous stem cell transplant (ASCT) performed in only 17% and rituximab maintenance given to 31%. With a median follow up of 47 months (range: 4-136), the 5-year overall survival (OS) was 69% (95% CI: 52%, 81%). Chemotherapy-naivety at HT was associated with a superior rate of CR (84% vs 54%, P = 0.057) and 5-year OS (82% vs 46%, P = 0.012). Rituximab maintenance was associated with a durable progression-free survival in induction responders. CONCLUSIONS: Excellent OS was observed in this modern cohort of patients treated with rituximab-containing induction and low rate of consolidation by ASCT, particularly in those who were chemotherapy-naïve at HT.

Venous thromboembolism in primary central nervous system lymphoma during frontline chemoimmunotherapy.

BACKGROUND: In primary central nervous system lymphoma (PCNSL), venous thromboembolism (VTE) can cause significant morbidity and hinder chemotherapy delivery. OBJECTIVES: To assess VTE incidence, timing and adequacy of inpatient and outpatient VTE prophylaxis in patients with PCNSL receiving chemoimmunotherapy with curative intent. PATIENTS/METHODS: We reviewed patients diagnosed with PCNSL between 1997 and 2018 who received methotrexate, procarbazine, and vincristine ± Rituximab. Patient demographics, VTE prophylaxis and incidence, adverse events of anticoagulation, and survival outcomes were collected. RESULTS: Fifty-one PCNSL patients were included (median 67 years [range, 32-87], 30 males [59%]). Thirteen patients (25%, 95% confidence interval [CI], 14-40) developed VTE at a median of 1.6 months from diagnosis (range, 0-4). Patients with Khorana Risk Score ≥2 were more likely to have VTE than those with a KRS < 2 (60% vs 15%; P = .01). Eighty-five percent had deviations from inpatient VTE prophylaxis guidelines, and outpatient prophylaxis was not routinely administered. Three patients required inferior vena cava filters. Hemorrhagic complications of anticoagulation included an intracranial hemorrhage from therapeutic anticoagulation and three cases of major bleeding from prophylactic anticoagulation. No patients died from VTE or its treatment. CONCLUSIONS: Patients with newly diagnosed PCNSL are at high risk of VTE. Further research is required into optimal VTE prophylaxis in PCNSL.

LIM domain only 2 (LMO2) expression distinguishes T-lymphoblastic leukemia/lymphoma from indolent T-lymphoblastic proliferations.

AIMS: An indolent T-lymphoblastic proliferation (iT-LBP) is a benign, reactive expansion of immature terminal deoxynucleotidyl transferase (TdT)-positive T cells found in extrathymic tissues. iT-LBP can be challenging to distinguish from malignant processes, specifically T-lymphoblastic lymphoma (T-LBL), given the overlapping clinical and histological features. Recently, it has been shown that LIM domain only 2 (LMO2) is overexpressed in T-LBL but not in reactive immature TdT+ T cells in the thymus. On the basis of these findings, the aim of this study was to investigate the expression of LMO2 by using immunohistochemistry and its role in differentiating iT-LBPs from T-LBLs. METHODS AND RESULTS: We retrospectively identified cases of iT-LBP and T-LBL from the pathology archives of four institutions. Seven iT-LBP cases (including five new cases that have not been reported in the literature) and 13 T-LBL cases were analysed. Clinical, morphological, immunophenotypic and molecular data were analysed. Immunohistochemical staining with LMO2 was performed on all iT-LBP and T-LBL cases. A review of five new iT-LBP cases showed similar morphological, immunophenotypic and molecular features to those of previously reported cases. All iT-LBP cases were negative for LMO2 (0/7), whereas 92% of T-LBL cases (12/13) expressed LMO2; the sensitivity was 92% (confidence interval 64-100%) and the specificity was 100% (confidence interval 59-100%). CONCLUSION: We confirm previously published findings that iT-LBP cases show highly overlapping morphological and immunophenotypic features with T-LBL. Importantly, LMO2 expression is a sensitive and specific marker with which to rule out iT-LBP.

Deep profiling of apoptotic pathways with mass cytometry identifies a synergistic drug combination for killing myeloma cells.

Multiple myeloma is an incurable and fatal cancer of immunoglobulin-secreting plasma cells. Most conventional therapies aim to induce apoptosis in myeloma cells but resistance to these drugs often arises and drives relapse. In this study, we sought to identify the best adjunct targets to kill myeloma cells resistant to conventional therapies using deep profiling by mass cytometry (CyTOF). We validated probes to simultaneously detect 26 regulators of cell death, mitosis, cell signaling, and cancer-related pathways at the single-cell level following treatment of myeloma cells with dexamethasone or bortezomib. Time-resolved visualization algorithms and machine learning random forest models (RFMs) delineated putative cell death trajectories and a hierarchy of parameters that specified myeloma cell survival versus apoptosis following treatment. Among these parameters, increased amounts of phosphorylated cAMP response element-binding protein (CREB) and the pro-survival protein, MCL-1, were defining features of cells surviving drug treatment. Importantly, the RFM prediction that the combination of an MCL-1 inhibitor with dexamethasone would elicit potent, synergistic killing of myeloma cells was validated in other cell lines, in vivo preclinical models and primary myeloma samples from patients. Furthermore, CyTOF analysis of patient bone marrow cells clearly identified myeloma cells and their key cell survival features. This study demonstrates the utility of CyTOF profiling at the single-cell level to identify clinically relevant drug combinations and tracking of patient responses for future clinical trials.

IRF4 Activity Is Required in Established Plasma Cells to Regulate Gene Transcription and Mitochondrial Homeostasis.

The transcription factor interferon regulatory factor 4 (IRF4) is critical for the development, maintenance, and function of plasma cells. The mechanism by which IRF4 exerts its action in mature plasma cells has been elusive due to the death of all such cells upon IRF4 loss. While we identify apoptosis as a critical pathway for the death of plasma cells caused by IRF4 loss, we also determine that IRF4 did not regulate the intrinsic apoptotic pathway directly. By using an inducible IRF4 deletion system in the presence of the overexpression of anti-apoptotic BCL2, we identify genes whose expression is coordinated by IRF4 and that in turn specify plasma cell identity and mitochondrial homeostasis.

Cytarabine-based induction immunochemotherapy in the front-line treatment of older patients with mantle cell lymphoma.

The role of cytarabine-based induction and autologous stem cell transplantation (ASCT) in front-line treatment of younger patients with mantle cell lymphoma (MCL) is well established, however the utility of intensive approaches in older patients remains unclear. This retrospective study compared first line treatment outcomes in patients aged 60 years or more, treated at six tertiary centres between 2000-2015. 70 patients included had a median age of 69 (60-91) and most (94%) demonstrated advanced stage disease. Treatment regimens included: R-CHOP-like (n = 39), alternating R-CHOP/R-DHAC (n = 10), R-HyperCVAD/R-MA (n = 7), R-CHOP/Cytarabine (Nordic Protocol) (n = 10) and other (n = 4). 16 patients underwent an ASCT. The median follow-up for surviving patients was 37 months. Compared to R-CHOP-like therapies, cytarabine-based regimens were associated with an improved overall response rate (ORR) of 70% vs 33% (p < 0.001) and overall survival (OS) (HR 0.541, [0.292-1.001], p = 0.05). No difference in efficacy between different cytarabine-based regimens was detected, but R-HyperCVAD/R-MA was associated with increased hospitalisation and transfusion requirements. Patients undergoing ASCT demonstrated an improved median OS (HR 0.108 [0.015-0.796], p = 0.029) but were significantly younger. These results reaffirm the use of cytarabine in MCL for selected patients aged over 60. Such regimens should be strongly considered for this population in frontline therapy.

Pembrolizumab plus lenalidomide and dexamethasone for patients with treatment-naive multiple myeloma (KEYNOTE-185): a randomised, open-label, phase 3 trial.

BACKGROUND: Lenalidomide and dexamethasone has been a standard of care in transplant-ineligible patients with newly diagnosed multiple myeloma. The addition of a third drug to the combination is likely to improve treatment efficacy. KEYNOTE-185 assessed the efficacy and safety of lenalidomide and dexamethasone with and without pembrolizumab in patients with previously untreated multiple myeloma. Here, we present the results of an unplanned interim analysis done to assess the benefit-risk of the combination at the request of the US Food and Drug Administration (FDA). METHODS: KEYNOTE-185 was a randomised, open-label, phase 3 trial done at 95 medical centres across 15 countries (Australia, Canada, France, Germany, Ireland, Israel, Italy, Japan, New Zealand, Norway, Russia, South Africa, Spain, UK, and USA). Transplantation-ineligible patients aged 18 years and older with newly diagnosed multiple myeloma, Eastern Cooperative Oncology Group performance status of 0 or 1, and who were treatment naive were enrolled, and randomly assigned 1:1 to receive either pembrolizumab plus lenalidomide and dexamethasone or lenalidomide and dexamethasone alone using an interactive voice or integrated web response system. Patients received oral lenalidomide 25 mg on days 1-21 and oral dexamethasone 40 mg on days 1, 8, 15, and 22 of repeated 28-day cycles, with or without intravenous pembrolizumab 200 mg every 3 weeks. The primary endpoint was progression-free survival, which was investigator-assessed because of early trial termination. Efficacy was analysed in all randomly assigned patients and safety was analysed in all patients who received at least one dose of study drug. This trial is registered at ClinicalTrials.gov, number NCT02579863, and it is closed for accrual. FINDINGS: Between Jan 7, 2016, and June 9, 2017, 301 patients were randomly assigned to the pembrolizumab plus lenalidomide and dexamethasone group (n=151) or the lenalidomide and dexamethasone group (n=150). On July 3, 2017, the FDA decided to halt the study because of the imbalance in the proportion of death between groups. At database cutoff (June 2, 2017), with a median follow-up of 6·6 months (IQR 3·4-9·6), 149 patients in the pembrolizumab plus lenalidomide and dexamethasone group and 145 in the lenalidomide and dexamethasone group had received their assigned study drug. Median progression-free survival was not reached in either group; progression-free survival estimates at 6-months were 82·0% (95% CI 73·2-88·1) versus 85·0% (76·8-90·5; hazard ratio [HR] 1·22; 95% CI 0·67-2·22; p=0·75). Serious adverse events were reported in 81 (54%) patients in the pembrolizumab plus lenalidomide and dexamethasone group versus 57 (39%) patients in the lenalidomide and dexamethasone group; the most common serious adverse events were pneumonia (nine [6%]) and pyrexia (seven [5%]) in the pembrolizumab plus lenalidomide and dexamethasone group and pneumonia (eight [6%]) and sepsis (two [1%]) in the lenalidomide and dexamethasone group. Six (4%) treatment-related deaths occurred in the pembrolizumab plus lenalidomide and dexamethasone group (cardiac arrest, cardiac failure, myocarditis, large intestine perforation, pneumonia, and pulmonary embolism) and two (1%) in the lenalidomide and dexamethasone group (upper gastrointestinal haemorrhage and respiratory failure). INTERPRETATION: The results from this unplanned, FDA-requested, interim analysis showed that the benefit-risk profile of pembrolizumab plus lenalidomide and dexamethasone is unfavourable for patients with newly diagnosed, previously untreated multiple myeloma. Long-term safety and survival follow-up is ongoing. FUNDING: Merck Sharp & Dohme, a subsidiary of Merck & Co, Inc (Kenilworth, NJ, USA).

Ocular infiltration as initial presentation of acute monocytic leukaemia transformed from chronic myelomonocytic leukaemia associated with BRAF V600E mutation.

Acute monocytic leukaemia (French-British-American classification: AML-M5b) is characterised by a predominance of cells of the monocytic lineage on bone marrow examination. Furthermore, a discerning feature is its tendency for tissue infiltration. While gum hypertrophy and hepatosplenomegaly are common, ocular involvement is rare. Here, we present a case of a 75-year-old man referred with proptosis and monocytosis-subsequently diagnosed as AML-M5b, whose disease course was distinguished by extensive tissue invasion (ocular, pulmonary, liver, spleen). Cytogenetics and molecular tests were consistent with blastic transformation of previously undiagnosed chronic myelomonocytic leukaemia, supported by the presence of long-standing, low-grade monocytosis. Notably, a BRAF V600E mutation was also detected-an oncogenic driver previously reported in de novo and therapy-related, but not chronic myelomonocytic leukaemia-transformed, AML-M5b. While an initial response to cytoreductive treatment was observed, his tissue-invasive disease soon progressed with worsening pulmonary infiltrates, disseminated intravascular coagulation and renal failure, resulting in death.