Anthony Linton

Safety and activity of microRNA-loaded minicells in patients with recurrent malignant pleural mesothelioma: a first-in-man, phase 1, open-label, dose-escalation study

BACKGROUND TargomiRs are minicells (EnGeneIC Dream Vectors) loaded with miR-16-based mimic microRNA (miRNA) and targeted to EGFR that are designed to counteract the loss of the miR-15 and miR-16 family miRNAs, which is associated with unsuppressed tumour growth in preclinical models of malignant pleural mesothelioma. We aimed to assess the safety, optimal dosing, and activity of TargomiRs in patients with malignant pleural mesothelioma. METHODS In this first-in-man, open-label, dose-escalation phase 1 trial at three major cancer centres in Sydney (NSW, Australia), we recruited adults (aged ≥18 years) with a confirmed diagnosis of malignant pleural mesothelioma, measurable disease, radiological signs of progression after previous chemotherapy, Eastern Cooperative Oncology Group performance status of 0 or 1, life expectancy of 3 months or more, immunohistochemical evidence of tumour EGFR expression, and adequate bone marrow, liver, and renal function. Patients were given TargomiRs via 20 min intravenous infusion either once or twice a week (3 days apart) in a traditional 3 + 3 dose-escalation design in five dose cohorts. The dose-escalation steps planned were 5 × 109, 7 × 109, and 9 × 109 TargomiRs either once or twice weekly, but after analysis of data from the first eight patients, all subsequent patients started protocol treatment at 1 × 109 TargomiRs. The primary endpoints were to establish the maximum tolerated dose of TargomiRs as measured by dose-limiting toxicity, define the optimal frequency of administration, and objective response (defined as the percentage of assessable patients with a complete or partial response), duration of response (defined as time from the first evidence of response to disease progression in patients who achieved a response), time to response (ie, time from start of treatment to the first evidence of response) and overall survival (defined as time from treatment allocation to death from any cause). Analyses were based on the full analysis set principle, including every patient who received at least one dose of TargomiRs. The study was closed for patient entry on Jan 3, 2017, and registered with ClinicalTrials.gov, number NCT02369198, and the Australian Registry of Clinical Trials, number ACTRN12614001248651. FINDINGS Between Sept 29, 2014, and Nov 24, 2016, we enrolled 27 patients, 26 of whom received at least one TargomiR dose (one patient died before beginning treatment). Overall, five dose-limiting toxicities were noted: infusion-related inflammatory symptoms and coronary ischaemia, respectively, in two patients given 5 × 109 TargomiRs twice weekly; anaphylaxis and cardiomyopathy, respectively, in two patients given 5 × 109 TargomiRs once weekly but who received reduced dexamethasone prophylaxis; and non-cardiac pain in one patient who received 5 × 109 TargomiRs once weekly. We established that 5 × 109 TargomiRs once weekly was the maximum tolerated dose. TargomiR infusions were accompanied by transient lymphopenia (25 [96%] of 26 patients), temporal hypophosphataemia (17 [65%] of 26 patients), increased aspartate aminotransferase or alanine aminotranferase (six [23%] of 26 patients), and increased alkaline phosphatase blood concentrations (two [8%]). Cardiac events occurred in five patients: three patients had electrocardiographic changes, one patient had ischaemia, and one patient had Takotsubo cardiomyopathy. Of the 22 patients who were assessed for response by CT, one (5%) had a partial response, 15 (68%) had stable disease, and six (27%) had progressive disease. The proportion of patients who achieved an objective response was therefore one (5%) of 22, and the duration of the objective response in that patient was 32 weeks. Median overall survival was 200 days (95% CI 94-358). During the trial, 21 deaths occurred, of which 20 were related to tumour progression and one was due to bowel perforation. INTERPRETATION The acceptable safety profile and early signs of activity of TargomiRs in patients with malignant pleural mesothelioma support additional studies of TargomiRs in combination with chemotherapy or immune checkpoint inhibitors. FUNDING Asbestos Diseases Research Foundation.

Factors associated with survival in a large series of patients with malignant pleural mesothelioma in New South Wales.

Background:Although the prognosis of most patients presenting with malignant pleural mesothelioma (MPM) is poor, a small proportion survives long term. We investigated factors associated with survival in a large patient series.Methods:All patients registered with the NSW Dust Diseases Board (2002–2009) were included in an analysis of prognostic factors using Kaplan–Meier and Cox regression analysis. On the basis of these analyses, we developed a risk score (Prognostic Index (PI)).Results:We identified 910 patients: 90% male; histology (epithelioid 60%; biphasic 13%; sarcomatoid 17%); stage (Tx-I-II 48%; III-IV 52%); and calretinin expression (91%). Treatment: chemotherapy(CT) 44%, and extrapleural-pneumonectomy (EPP) 6%. Median overall survival (OS) was 10.0 months. Longer OS was associated with: age <70 (13.5 vs 8.5 months; P<0.001); female gender (12.0 vs 9.9 months; P<0.001); epithelioid subtype (13.3 vs 6.2 months; P<0.001); ECOG status 0 (27.4 vs 9.7 months; P=0.015), calretinin expression (10.9 vs 5.5 months; P<0.001); neutrophil–lymphocyte ratio (NLR) <5 (11.9 vs 7.5 months; P<0.001); platelet count <400 (11.5 vs 7.2 months; P<0.001); and normal haemoglobin (16.4 vs 8.8 months; P<0.001). On time-dependent analysis, patients receiving pemetrexed-based chemotherapy (HR=0.83; P=0.048) or EPP (HR=0.41; P<0.001) had improved survival. Age, gender, histology, calretinin and haematological factors remained significant on multivariate analysis. In all, 24% of patients survived >20 months: 16% of these receiving EPP, and 66% CT. The PI offered improved prognostic discrimination over one of the existing prognostic models (EORTC).Conclusions:We identified calretinin expression, age, gender, histological subtype, platelet count and haemoglobin level as independent prognostic factors. Patients undergoing EPP or pemetrexed-based chemotherapy demonstrated better survival, but 84% and 34% of long survivors, respectively, did not receive radical surgery or chemotherapy.

The ticking time-bomb of asbestos: Its insidious role in the development of malignant mesothelioma

The relationship between asbestos exposure and malignant mesothelioma (MM) has been well established. Despite bans on asbestos use in an increasing number of nations, the prolonged latency from exposure to diagnosis, and the ongoing presence and use of these dangerous fibres, have led to the increasing prevalence of this deadly disease worldwide. Whilst occupational contact has been implicated in the bulk of diagnosed cases over the past 50 years, a significant proportion of disease has been linked to para-occupational, domestic and environmental exposure. In this review, we will provide an update on the impact of historical and ongoing asbestos contact in both occupational and non-occupational settings. Furthermore, we will address the unresolved controversies surrounding the use of chrysotile asbestos, the effect of gender and genetics on development of this disease, childhood mesothelioma and co-aetiological factors including SV40 exposure.

MiR‐Score: A novel 6‐microRNA signature that predicts survival outcomes in patients with malignant pleural mesothelioma

Prognosis of malignant pleural mesothelioma (MPM) is poor, and predicting the outcomes of treatment is difficult. Here we investigate the potential of microRNA expression to estimate prognosis of MPM patients.

An RNAi-based screen reveals PLK1, CDK1 and NDC80 as potential therapeutic targets in malignant pleural mesothelioma

Background:Malignant pleural mesothelioma (MPM) is an aggressive tumour originating in the thoracic mesothelium. Prognosis remains poor with 9- to 12-month median survival, and new targets for treatments are desperately needed.Methods:Utilising an RNA interference (RNAi)-based screen of 40 genes overexpressed in tumours, including genes involved in the control of cell cycle, DNA replication and repair, we investigated potential therapeutic targets for MPM. Following in vitro characterisation of the effects of target silencing on MPM cells, candidates were assessed in tumour samples from 154 patients.Results:Gene knockdown in MPM cell lines identified growth inhibition following knockdown of NDC80, CDK1 and PLK1. Target knockdown induced cell-cycle arrest and increased apoptosis. Using small-molecule inhibitors specific for these three proteins also led to growth inhibition of MPM cell lines, and Roscovitine (inhibitor of CDK1) sensitised cells to cisplatin. Protein expression was also measured in tumour samples, with markedly variable levels of CDK1 and PLK1 noted. PLK1 expression in over 10% of cells correlated significantly with a poor prognosis.Conclusion:These results suggest that RNAi-based screening has utility in identifying new targets for MPM, and that inhibition of NDC80, CDK1 and PLK1 may hold promise for treatment of this disease.

Glasgow Prognostic Score As a Prognostic Factor in Metastatic Castration-Resistant Prostate Cancer Treated With Docetaxel-Based Chemotherapy

BACKGROUND The modified Glasgow Prognostic Score (mGPS), derived from C-reactive protein (CRP) and albumin levels, and the neutrophil-lymphocyte ratio (NLR) have demonstrated prognostic significance in a number of malignancies. PATIENTS AND METHODS Baseline mGPS and NLR were calculated in a prospective cohort of chemotherapy-naive patients with metastatic castration-resistant prostate cancer (mCRPC) (AT-101-CS-205 trial) who received docetaxel and prednisone ± AT101. Cox proportional hazards regression models estimated their effects on overall survival (OS). RESULTS Of 220 eligible patients, mGPS and neutrophil and lymphocyte counts were available for 184, 193, and 112 patients, respectively. Albumin (hazard ratio [HR], 0.28; 95% confidence interval [CI]: 0.14-0.56; P < .001) and CRP (HR, 1.22; 95% CI, 1.00-1.48; P = .048) were independently prognostic for OS. An association between mGPS and OS was found (HR, 1.87; 95% CI, 1.35-2.59; P < .001; median survival, 23.5 months at mGPS 0 vs. 9.8 months at mGPS 2). mGPS was significant after controlling for 3 previously published nomograms or NLR (P ≤ .001). NLR was not prognostic for OS (HR, 0.98; P = .91), and no association between mGPS and toxicity was noted. CONCLUSION Our results demonstrate the prognostic role of the mGPS in mCRPC over variables previously identified. mGPS is inexpensive, easily measured, and could be incorporated into routine clinical testing if our results are confirmed in a subsequent validation study. The utility of the NLR in mCRPC remains uncertain despite evidence in other malignancies.

Tumor Suppressor microRNAs Contribute to the Regulation of PD-L1 Expression in Malignant Pleural Mesothelioma

Introduction: The upregulation of programmed death ligand 1 (PD‐L1) is found in many cancers and contributes to evasion of the hosts immune defense. In malignant pleural mesothelioma (MPM), PD‐L1 expression is associated with the nonepithelioid histological subtype and poor prognosis, but the pathways involved in control of PD‐L1 expression in MPM are poorly understood. To address one possible means of PD‐L1 regulation we investigated the relationship between dysregulated microRNA levels and PD‐L1 expression. Methods: PD‐L1 expression was analyzed by immunohistochemistry in tissue microarrays prepared from samples from patients undergoing an operation (pleurectomy with or without decortication). MicroRNA expression was analyzed by reverse‐transcriptase quantitative polymerase chain reaction. Regulation of PD‐L1 expression in cell lines was assessed after transfection with microRNA mimics and small interfering RNAs. Interaction between microRNAs and PD‐L1 was analyzed by using argonaute‐2 immunoprecipitation and a luciferase reporter assay. Results: In a series of 72 patients with MPM, 18 (25%) had positive PD‐L1 staining, and this was more common in patients with the nonepithelioid subtype (p = 0.01). PD‐L1 expression was associated with poor survival (median overall survival 4.0 versus 9.2 months with positive versus negative PD‐L1 expression [p < 0.001]), and in multivariate analyses, PD‐L1 expression remained a significant adverse prognostic indicator (hazard ratio = 2.2, 95% confidence interval: 1.2–4.1, p < 0.01). In the same patient series, PD‐L1 expression was also associated with downregulation of microRNAs previously shown to have tumor suppressor activity in MPM. The median microRNA expression levels of miR‐15b, miR‐16, miR‐193a‐3p, miR‐195, and miR‐200c were significantly lower in the PD‐L1–positive samples. Transfecting MPM cell lines with mimics corresponding to miR‐15a and miR‐16, both of which are predicted to target PD‐L1, led to downregulation of PD‐L1 mRNA and protein. In addition, miR‐193a‐3p, with an alternative G‐U–containing target site, also caused PD‐L1 downregulation. Conclusions: Together, these data suggest that tumor suppressor microRNAs contribute to the regulation of PD‐L1 expression in MPM.

Inflammation in malignant mesothelioma - friend or foe?

The relationship between inflammation and cancerous growth has been extensively investigated over the past 150 years. Following Virchow’s identification of leukocytes within neoplastic tissue in 1863 (1), the role of inflammatory cells and pathways in the pathogenesis of a variety of tumour groups has become well established. In a variety of malignancies, environmental and infective agents are seen to play critical roles in the production of tissue damage and inflammatory reactions. Furthermore, cytokines, chemokines and angiogenic factors produced in chronic inflammatory states provide a microenvironment favourable for cellular survival and angiogenesis (2). Cytokines such as interleukin (IL)-6, IL-10 and IL-17/23 are postulated to be at the centre of a signalling network, activating pathways such as STAT3 or NFƙB (3). In the case of malignant pleural mesothelioma (MPM), asbestos fibre exposure occupies this central pathogenic role, and the ensuing alteration of immune-competent cells may result in a decline in tumoral immunity (4). The mechanisms by which inflammatory processes impact on the development of MPM remain incompletely understood, and are beyond the scope of this review. However, there is an increasing awareness of the relationship between the degree of both local and systemic inflammatory response and the prognosis of patients with MPM. We hereby review the available evidence on the impact of inflammation on survival in patients with MPM and examine the potential therapeutic implications.

Immunohistochemistry in the diagnosis of malignant pleural mesothelioma: Trends in Australia and a literature review

The accurate diagnosis of malignant pleural mesothelioma (MPM) is essential for therapeutic and legal reasons. In 2006 the International Mesothelioma Panel advocated the use of a panel, including two mesothelial and two non‐mesothelial immunohistochemical (IHC) markers. We assessed the changing use of IHC for the diagnosis of MPM in Australia over two decades in the context of current best practice.

Geographic and socioeconomic factors in patients with malignant pleural mesothelioma in New South Wales and their impact upon clinical outcomes.

Whilst the impact of clinicopathological factors on the prognosis of malignant pleural mesothelioma (MPM) is well understood, socioeconomic and geographic factors have received less attention. We analysed the relationship between geographic and socioeconomic factors upon survival and treatment provision in a large series of patients with MPM.