Brian A. Jonas

Corepressors: custom tailoring and alterations while you wait

A diverse cadre of metazoan transcription factors mediate repression by recruiting protein complexes containing the SMRT (silencing mediator of retinoid and thyroid hormone receptor) or N-CoR (nuclear receptor corepressor) corepressors. SMRT and N-CoR nucleate the assembly of still larger corepressor complexes that perform the specific molecular incantations necessary to confer transcriptional repression. Although SMRT and N-CoR are paralogs and possess similar molecular architectures and mechanistic strategies, they nonetheless exhibit distinct molecular and biological properties. It is now clear that the functions of both SMRT and N-CoR are further diversified through alternative mRNA splicing, yielding a series of corepressor protein variants that participate in distinctive transcription factor partnerships and display distinguishable repression properties. This review will discuss what is known about the structure and actions of SMRT, N-CoR, and their splicing variants, and how alternative splicing may allow the functions of these corepressors to be adapted and tailored to different cells and to different developmental stages.

Safety and preliminary efficacy of venetoclax with decitabine or azacitidine in elderly patients with previously untreated acute myeloid leukaemia: a non-randomised, open-label, phase 1b study

BACKGROUND Elderly patients (aged ≥65 years) with acute myeloid leukaemia have poor outcomes and no effective standard-of-care therapy exists. Treatment with hypomethylating agents such as azacitidine and decitabine is common, but responses are modest and typically short-lived. The oral anti-apoptotic B-cell lymphoma 2 protein inhibitor, venetoclax, has shown promising single-agent activity in patients with relapsed or refractory acute myeloid leukaemia and preclinical data suggested synergy between hypomethylating agents and venetoclax, which led to this combination phase 1b study. METHODS Previously untreated patients aged 65 years and over with acute myeloid leukaemia who were ineligible for standard induction therapy were enrolled into this non-randomised, open-label, phase 1b study. Patients were required to have an Eastern Cooperative Oncology Group performance status of 0-2 and either intermediate-risk or poor-risk cytogenetics. Patients were enrolled into one of three groups for the dose-escalation phase of this study: group A (venetoclax and intravenous decitabine 20 mg/m2 [days 1-5 of each 28-day cycle]), group B (venetoclax and subcutaneous or intravenous azacitidine 75 mg/m2 [days 1-7 of each 28-day cycle]), and group C (a venetoclax and decitabine substudy with the oral CYP3A inhibitor posaconazole, 300 mg twice on cycle 1, day 21, and 300 mg once daily from cycle 1, days 22-28, to assess its effect on venetoclax pharmacokinetics). Dose escalation followed a standard 3 + 3 design with at least three evaluable patients enrolled per cohort; daily target doses of venetoclax for groups A and B were 400 mg (cohort 1), 800 mg (cohorts 2 and 3), and 1200 mg (cohort 4), and 400 mg for group C. The primary endpoints were the safety and pharmacokinetics of venetoclax plus decitabine or azacitidine, and to determine the maximum tolerated dose and recommended phase 2 dose. Secondary endpoints included the preliminary anti-leukaemic activity of venetoclax with decitabine or azacitidine through the analysis of overall response, duration of response, and overall survival. We analysed safety, pharmacokinetics, and anti-leukaemic activity in all patients who received one or more venetoclax doses. The expansion phase of the study is ongoing but is closed to accrual. This trial is registered with ClinicalTrials.gov, number NCT02203773. FINDINGS 57 patients were enrolled in the study. 23 patients in group A and 22 patients in group B were enrolled between Nov 19, 2014, and Dec 15, 2015, and 12 patients in group C were enrolled between June 14, 2015, and Jan 16, 2016. As of data cutoff on June 15, 2016, the most common grade 3-4 treatment-emergent adverse events were thrombocytopenia (27 [47%] of 57 patients; nine in group A, 13 in group B, and five in group C), febrile neutropenia (24 [42%] of 57; 11 in group A, ten in group B, and three in group C), and neutropenia (23 [40%] of 57; 12 in group A, eight in group B, and three in group C). The most common serious treatment-emergent adverse event in groups A and B was febrile neutropenia (seven [30%] of 23 patients vs seven [32%] of 22), whereas in group C it was lung infection (four [33%] of 12 patients). 49 (86%) of 57 patients had treatment-related adverse events; the most common in groups A and B included nausea (12 [52%] patients vs seven [32%] patients), fatigue (six [26%] patients vs seven [32%]), and decreased neutrophil count (six [26%] patients vs six [27%]), whereas in group C the most common were nausea (seven [58%] of 12 patients), leucopenia (six [50%]), vomiting (five [42%]), and decreased platelet count (five [42%]). The maximum tolerated dose was not reached. The recommended phase 2 dose was 400 mg once a day or 800 mg with an interrupted dosing schedule (safety expansion). In total, four (7%) of 57 patients had died within 30 days of the first venetoclax dose caused by sepsis (group B), bacteraemia (group A), lung infection (group C), and respiratory failure (group A). Tumour lysis syndrome was not observed. Decitabine and azacitidine did not substantially affect venetoclax exposures. Overall, 35 (61%; 95% CI 47·6-74·0) of 57 patients achieved complete remission or complete remission with incomplete marrow recovery. In groups A and B, 27 (60%; 95% CI 44·3-74·3) of 45 patients had complete remission or complete remission with incomplete marrow recovery. INTERPRETATION Venetoclax plus hypomethylating agent therapy seems to be a novel, well-tolerated regimen with promising activity in this underserved patient population. Evaluation of expansion cohorts is ongoing at 400 mg and 800 mg doses using both hypomethylating agent combinations. FUNDING AbbVie and Genentech.

Alternative mRNA splicing of corepressors generates variants that play opposing roles in adipocyte differentiation.

Background: The SMRT and NCoR corepressors play key biological roles in transcriptional repression. Results: Alternative mRNA splicing produces corepressor variants that can exert opposite effects on adipocyte differentiation. Conclusion: Corepressors are diversified by alternative mRNA splicing, allowing one locus to encode multiple proteins with distinct functions. Significance: Changes in alternative splicing may help drive the differentiation and customize the physiology of specific cell types. The SMRT and NCoR corepressors partner with, and help mediate repression by, a wide variety of nuclear receptors and non-receptor transcription factors. Both SMRT and NCoR are expressed by alternative mRNA splicing, resulting in the production of a series of interrelated corepressor variants that differ in their tissue distribution and in their biochemical properties. We report here that different corepressor splice variants can exert opposing transcriptional and biological effects during adipocyte differentiation. Most notably, the NCoRω splice variant inhibits, whereas the NCoRδ splice variant promotes, adipogenesis. Furthermore, the ratio of NCoRω to NCoRδ decreases during adipogenic differentiation. We propose that this alteration in corepressor splicing helps convert the cellular transcriptional program from one that maintains the pre-adipocyte in an undifferentiated state to a new transcriptional context that promotes differentiation and helps establish the proper physiology of the mature adipocyte.

MDS prognostic scoring systems - Past, present, and future

The myelodysplastic syndromes (MDS) are a heterogeneous group of clonal myeloid haemopathies characterized by defective differentiation of haematopoietic cells and expansion of the abnormal clone. This leads to bone marrow failure with the resulting peripheral blood cytopenias and evolution to or toward acute myeloid leukaemia that characterize MDS clinically. The clinical heterogeneity of MDS has led several groups to analyze patient and clinical characteristics to develop prognostic scoring systems yielding estimates of overall and leukaemia-free survival to guide clinical decision-making. These models have evolved over time as our understanding of the pathogenesis, natural history, and treatment of MDS has improved. Rapid advances in flow cytometric analysis, adjuncts to standard metaphase cytogenetics, and gene mutation analysis are revolutionizing our understanding of MDS pathogenesis and prognosis. Despite the existence of multiple well-validated prognostic scoring systems, further refinements of current models with these new sources of prognostic data are needed and are described herein.

Early mortality and complications in hospitalized adult Californians with acute myeloid leukaemia

Few studies have evaluated the impact of complications, sociodemographic and clinical factors on early mortality (death ≤60 days from diagnosis) in acute myeloid leukaemia (AML) patients. Using data from the California Cancer Registry linked to hospital discharge records from 1999 to 2012, we identified patients aged ≥15 years with AML who received inpatient treatment (N = 6359). Multivariate logistic regression analyses were used to assess the association of complications with early mortality, adjusting for sociodemographic factors, comorbidities and hospital type. Early mortality decreased over time (25·3%, 1999–2000; 16·8%, 2011–2012) across all age groups, but was higher in older patients (6·9%, 15–39, 11·4%, 40–54, 18·6% 55–65, and 35·8%, >65 years). Major bleeding [Odds ratio (OR) 1·5, 95% confidence interval (CI) 1·3–1·9], liver failure (OR 1·9, 95% CI 1·1–3·1), renal failure (OR 2·4, 95% CI 2·0–2·9), respiratory failure (OR 7·6, 95% CI 6·2–9·3) and cardiac arrest (OR 15·8, 95% CI 8·7–28·6) were associated with early mortality. Higher early mortality was also associated with single marital status, low neighbourhood socioeconomic status, lack of health insurance and comorbidities. Treatment at National Cancer Institute‐designated cancer centres was associated with lower early mortality (OR 0·5, 95% CI 0·4–0·6). In conclusion, organ dysfunction, hospital type and sociodemographic factors impact early mortality. Further studies should investigate how differences in healthcare delivery affect early mortality.

Optimal Molecular Methods in Detecting p190BCR-ABL Fusion Variants in Hematologic Malignancies: A Case Report and Review of the Literature

Patients with BCR-ABL1 positive hematologic malignancies and Philadelphia-like B-lymphoblastic leukemia (B-ALL) are potential candidates for targeted therapy with tyrosine kinase inhibitors (TKI). Before TKIs, patients with B-ALL had a much worse prognosis and current treatments with targeted TKI therapy have improved outcomes. Thus, the detection of BCR-ABL1 is crucial and a false negative BCR-ABL1 result may adversely affect patient care. We report a case of a 76-year-old male with a new diagnosis of B-ALL who was initially found to be BCR-ABL1 negative by quantitative polymerase chain reaction (PCR). A concurrent qualitative PCR was performed which detected a positive BCR-ABL1 result that was confirmed by a next generation sequencing (NGS) based assay and identified as the rare fusion variant e1a3 of p190BCR-ABL. Based on this result, the patient was placed on dasatinib as a targeted therapy. In the era of molecular diagnostic medicine and targeted therapy, it is essential to have an understanding of the limitations of molecular assays and to follow a comprehensive diagnostic approach in order to detect common abnormalities and rare variants. Incorporating NGS methods in an algorithmic manner into the standard diagnostic PCR-based approach for BCR-ABL1 will aid in minimizing false negative results.

Combination of an oncolytic virus with PD-L1 blockade keeps cancer in check

An oncolytic vaccinia virus expressing CXCL11 combined with PD-L1 blockade significantly reduces tumor burden and improves survival in murine cancer models. An oncolytic vaccinia virus expressing CXCL11 combined with PD-L1 blockade significantly reduces tumor burden and improves survival in murine cancer models.

Nanomicelle formulation modifies the pharmacokinetic profiles and cardiac toxicity of daunorubicin

BACKGROUND Treatment with daunorubicin (DNR) in acute myeloid leukemia is moderately effective and associated with significant side effects, including cardiac toxicity. We recently developed a nanomicellar formulation of DNR that specifically targets acute myeloid leukemia stem cells. MATERIALS & METHODS Pharmacokinetics analysis of free DNR, DNR in nanomicellar formulations was performed in Balb/c mice and Sprague-Dawley rats. Histochemical staining, caspase 3/7, troponin and creatine kinase MB isoenzyme were used to assess toxicity. RESULTS Compared with free DNR, the nanomicellar formulations of DNR had less cardiotoxicity as evidenced by milder histopathological changes, lower caspase 3/7 activity in heart tissue (p = 0.002), lower plasma creatine kinase MB isoenzyme (p = 0.002) and troponin concentrations (p = 0.001) postinjection. The area under curve concentration of DNR in micelles increased by 31.9-fold in mice (p < 0.0001) and 22.0-fold higher in rats (p < 0.001). CONCLUSION Leukemia stem cell-targeting micelles dramatically change the pharmacokinetics and reduce the cardiac toxicity of DNR, which may enable improved DNR-based treatment of acute myeloid leukemia.

Acquired Elliptocytosis as a Manifestation of Myelodysplastic Syndrome with Ring Sideroblasts and Multilineage Dysplasia

Acquired elliptocytosis is a known but rarely described abnormality in the myelodysplastic syndromes (MDS). Here we report the case of an elderly male who was admitted to the hospital with chest pain, dyspnea, and fatigue and was found to be anemic with an elliptocytosis that had only recently been noted on peripheral smears of his blood. After bone marrow biopsy he was diagnosed with MDS with ring sideroblasts and multilineage dysplasia and acquired elliptocytosis. Here we report a rare case of acquired elliptocytosis cooccurring with MDS with ring sideroblasts and multilineage dysplasia.

Subsequent primary malignancies after diffuse large B-cell lymphoma in the modern treatment era

With the addition of rituximab and other treatment advances, survival after diffuse large B‐cell lymphoma (DLBCL) has improved, but subsequent primary malignancies (SPMs) have emerged as an important challenge for DLBCL survivorship. We calculated standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for SPMs among 23 879 patients who survived at least 1 year after a first primary DLBCL diagnosed during 1989–2012, compared to the general population in California. Cumulative incidence (CMI) of SPMs, accounting for the competing risk of death, also was calculated. We found that the incidence of acute myeloid leukaemia (AML) nearly doubled in the post‐rituximab era [SIR (95% CI) 4·39 (2·51–7·13) pre‐ (1989–2000) and 8·70 (6·62–11·22) post‐rituximab (2001–2012)]. Subsequent thyroid cancer was rare pre‐rituximab, but increased substantially after 2001 [0·66 (0·08–2·37) vs. 2·27(1·44–3·41)]. The 5‐year CMI for all SPMs (4·77% pre‐ vs. 5·41% post‐rituximab, P = 0·047), AML (0·15% vs. 0·41%, P = 0·003), thyroid cancer (0·03% vs. 0·15%, P = 0·003) and melanoma (0·25% vs. 0·42%, P = 0·020) were greater in DLBCL patients diagnosed in the post‐ versus pre‐rituximab period. This study provides insight into the changing pattern of SPM occurrence after the introduction of rituximab, which may elucidate the aetiology of SPMs and should guide future cancer surveillance efforts among DLBCL patients.