Melbourne Medical School Collected Works - Research Publications
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ItemAssociation of programmed death ligand-1 (PD-L1) expression with treatment outcomes in patients with BRAF mutation-positive melanoma treated with vemurafenib or cobimetinib combined with vemurafenib(WILEY, 2018-07)The prognostic significance of programmed death ligand-1 (PD-L1) on treatment outcomes in patients receiving BRAF with or without MEK inhibitors is not well understood. This retrospective exploratory analysis evaluated the association of tumour PD-L1 expression with progression-free survival (PFS) and overall survival (OS) among 210 patients in the coBRIM trial treated with cobimetinib plus vemurafenib or placebo plus vemurafenib. In the vemurafenib cohort, there was a trend of increased PFS and OS in those with PD-L1+ melanoma, with hazard ratios (HRs; PD-L1+ vs. PD-L1- ) of 0.70 (95% CI, 0.46-1.07) and 0.69 (95% CI, 0.42-1.13) for PFS and OS, respectively. However, in patients treated with cobimetinib plus vemurafenib, a similar trend was not observed with HRs (PD-L1+ versus PD-L1- ) of 1.04 (95% CI, 0.66-1.68) and 0.94 (95% CI, 0.57-1.57) for PFS and OS, respectively. The combination cobimetinib plus vemurafenib appears to overcome the poor prognosis associated with low PD-L1 expression.
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ItemReal-world treatment patterns and outcomes among metastatic cutaneous melanoma patients treated with ipilimumab(WILEY, 2018-06)BACKGROUND: There is a scarcity of real-world data on treatment patterns and outcomes among advanced melanoma patients treated with immunotherapies including ipilimumab, an anti-CTLA-4 antibody approved since 2011. OBJECTIVE: To evaluate ipilimumab and postipilimumab treatment patterns and outcomes among patients with advanced melanoma in Australia, Germany, Italy and Spain, following regulatory approval. METHODS: Retrospective multicentre, multinational, observational chart review study. Data were extracted from the start of ipilimumab therapy until the end of at least 40 weeks of follow-up, or death. RESULTS: Data from 371 patients (Australia, 103; Germany, 152; Italy, 76; Spain, 40) were analysed. Mean age was 65 years; 62% were male. Eastern Cooperative Oncology Group performance status (ECOG PS) was 0 or 1 for 94%. In 67%, ipilimumab was initially received as second-line or later therapy. Patients received on average 3.4 ipilimumab doses. The ipilimumab-refractory cohort comprised of 226 patients. Of these, 17% in Australia, 47% in Germany, 29% in Italy and 14% in Spain received another antimelanoma treatment after ipilimumab including chemotherapy in 26% and BRAF/other kinase inhibitors in 11%. Ipilimumab-refractory patients who received postipilimumab treatment showed a 40% reduced hazard of dying than those not receiving treatment after ipilimumab (HR 0.60; 95% CI 0.43-0.83), after adjustment for potential confounders. CONCLUSION: During the time observed, ipilimumab was mainly used as second-line or later therapy. A significant proportion of patients received postipilimumab therapy, most of which was chemotherapy. Nevertheless, overall survival following progression on ipilimumab treatment remained poor, highlighting the need for research to develop more effective end-of-life treatment options.
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ItemThe state of melanoma: challenges and opportunities(WILEY-BLACKWELL, 2016-07)The Melanoma Research Foundation (MRF) has charted a comprehensive assessment of the current state of melanoma research and care. Intensive discussions among members of the MRF Scientific Advisory Council and Breakthrough Consortium, a group that included clinicians and scientists, focused on four thematic areas - diagnosis/early detection, prevention, tumor cell dormancy (including metastasis), and therapy (response and resistance). These discussions extended over the course of 2015 and culminated at the Society of Melanoma Research 2015 International Congress in November. Each of the four groups has outlined their thoughts as per the current status, challenges, and opportunities in the four respective areas. The current state and immediate and long-term needs of the melanoma field, from basic research to clinical management, are presented in the following report.
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ItemNo Preview AvailableClinical efficacy of a RAF inhibitor needs broad target blockade in BRAF-mutant melanoma(NATURE PUBLISHING GROUP, 2010-09)B-RAF is the most frequently mutated protein kinase in human cancers. The finding that oncogenic mutations in BRAF are common in melanoma, followed by the demonstration that these tumours are dependent on the RAF/MEK/ERK pathway, offered hope that inhibition of B-RAF kinase activity could benefit melanoma patients. Herein, we describe the structure-guided discovery of PLX4032 (RG7204), a potent inhibitor of oncogenic B-RAF kinase activity. Preclinical experiments demonstrated that PLX4032 selectively blocked the RAF/MEK/ERK pathway in BRAF mutant cells and caused regression of BRAF mutant xenografts. Toxicology studies confirmed a wide safety margin consistent with the high degree of selectivity, enabling Phase 1 clinical trials using a crystalline formulation of PLX4032 (ref. 5). In a subset of melanoma patients, pathway inhibition was monitored in paired biopsy specimens collected before treatment initiation and following two weeks of treatment. This analysis revealed substantial inhibition of ERK phosphorylation, yet clinical evaluation did not show tumour regressions. At higher drug exposures afforded by a new amorphous drug formulation, greater than 80% inhibition of ERK phosphorylation in the tumours of patients correlated with clinical response. Indeed, the Phase 1 clinical data revealed a remarkably high 81% response rate in metastatic melanoma patients treated at an oral dose of 960 mg twice daily. These data demonstrate that BRAF-mutant melanomas are highly dependent on B-RAF kinase activity.
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ItemCDC25B Overexpression Stabilises Centrin 2 and Promotes the Formation of Excess Centriolar Foci(PUBLIC LIBRARY SCIENCE, 2013-07-01)CDK-cyclin complexes regulate centriole duplication and microtubule nucleation at specific cell cycle stages, although their exact roles in these processes remain unclear. As the activities of CDK-cyclins are themselves positively regulated by CDC25 phosphatases, we investigated the role of centrosomal CDC25B during interphase. We report that overexpression of CDC25B, as is commonly found in human cancer, results in a significant increase in centrin 2 at the centrosomes of interphase cells. Conversely, CDC25B depletion causes a loss of centrin 2 from the centrosome, which can be rescued by treatment with the proteasome inhibitor MG132. CDC25B overexpression also promotes the formation of excess centrin 2 "foci". These foci can accumulate other centrosome proteins, including γ-tubulin and PCM-1, and can function as microtubule organising centres, indicating that these represent functional centrosomes. Formation of centrin 2 foci can be blocked by specific inhibition of CDK2 but not CDK1. CDK2-mediated phosphorylation of Monopolar spindle 1 (Mps1) at the G1/S transition is essential for the initiation of centrosome duplication, and Mps1 is reported to phosphorylate centrin 2. Overexpression of wild-type or non-degradable Mps1 exacerbated the formation of excess centrin 2 foci induced by CDC25B overexpression, while kinase-dead Mps1 has a protective effect. Together, our data suggest that CDC25B, through activation of a centrosomal pool of CDK2, stabilises the local pool of Mps1 which in turn regulates the level of centrin 2 at the centrosome. Overexpression of CDC25B may therefore contribute to tumourigenesis by perturbing the natural turnover of centrosome proteins such as Mps1 and centrin 2, thus resulting in the de novo assembly of extra-numerary centrosomes and potentiating chromosome instability.
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ItemFuture perspectives in melanoma research: meeting report from the "Melanoma Bridge": Napoli, December 3rd-6th 2014(BMC, 2015-11-30)The fourth "Melanoma Bridge Meeting" took place in Naples, December 3-6th, 2014. The four topics discussed at this meeting were: Molecular and Immunological Advances, Combination Therapies, News in Immunotherapy, and Tumor Microenvironment and Biomarkers. Until recently systemic therapy for metastatic melanoma patients was ineffective, but recent advances in tumor biology and immunology have led to the development of new targeted and immunotherapeutic agents that prolong progression-free survival (PFS) and overall survival (OS). New therapies, such as mitogen-activated protein kinase (MAPK) pathway inhibitors as well as other signaling pathway inhibitors, are being tested in patients with metastatic melanoma either as monotherapy or in combination, and all have yielded promising results. These include inhibitors of receptor tyrosine kinases (BRAF, MEK, and VEGFR), the phosphatidylinositol 3 kinase (PI3K) pathway [PI3K, AKT, mammalian target of rapamycin (mTOR)], activators of apoptotic pathway, and the cell cycle inhibitors (CDK4/6). Various locoregional interventions including radiotherapy and surgery are still valid approaches in treatment of advanced melanoma that can be integrated with novel therapies. Intrinsic, adaptive and acquired resistance occur with targeted therapy such as BRAF inhibitors, where most responses are short-lived. Given that the reactivation of the MAPK pathway through several distinct mechanisms is responsible for the majority of acquired resistance, it is logical to combine BRAF inhibitors with inhibitors of targets downstream in the MAPK pathway. For example, combination of BRAF/MEK inhibitors (e.g., dabrafenib/trametinib) have been demonstrated to improve survival compared to monotherapy. Application of novel technologies such sequencing have proven useful as a tool for identification of MAPK pathway-alternative resistance mechanism and designing other combinatorial therapies such as those between BRAF and AKT inhibitors. Improved survival rates have also been observed with immune-targeted therapy for patients with metastatic melanoma. Immune-modulating antibodies came to the forefront with anti-CTLA-4, programmed cell death-1 (PD-1) and PD-1 ligand 1 (PD-L1) pathway blocking antibodies that result in durable responses in a subset of melanoma patients. Agents targeting other immune inhibitory (e.g., Tim-3) or immune stimulating (e.g., CD137) receptors and other approaches such as adoptive cell transfer demonstrate clinical benefit in patients with melanoma as well. These agents are being studied in combination with targeted therapies in attempt to produce longer-term responses than those more typically seen with targeted therapy. Other combinations with cytotoxic chemotherapy and inhibitors of angiogenesis are changing the evolving landscape of therapeutic options and are being evaluated to prevent or delay resistance and to further improve survival rates for this patient population. This meeting's specific focus was on advances in combination of targeted therapy and immunotherapy. Both combination targeted therapy approaches and different immunotherapies were discussed. Similarly to the previous meetings, the importance of biomarkers for clinical application as markers for diagnosis, prognosis and prediction of treatment response was an integral part of the meeting. The overall emphasis on biomarkers supports novel concepts toward integrating biomarkers into contemporary clinical management of patients with melanoma across the entire spectrum of disease stage. Translation of the knowledge gained from the biology of tumor microenvironment across different tumors represents a bridge to impact on prognosis and response to therapy in melanoma.
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ItemCombination therapies to inhibit the RAF/MEK/ERK pathway in melanoma: we are not done yet(FRONTIERS MEDIA SA, 2015-07-17)
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ItemTRIM16 inhibits proliferation and migration through regulation of interferon beta 1 in melanoma cells(IMPACT JOURNALS LLC, 2014-10-30)High basal or induced expression of the tripartite motif protein, TRIM16, leads to reduce cell growth and migration of neuroblastoma and skin squamous cell carcinoma cells. However, the role of TRIM16 in melanoma is currently unknown. TRIM16 protein levels were markedly reduced in human melanoma cell lines, compared with normal human epidermal melanocytes due to both DNA methylation and reduced protein stability. TRIM16 knockdown strongly increased cell migration in normal human epidermal melanocytes, while TRIM16 overexpression reduced cell migration and proliferation of melanoma cells in an interferon beta 1 (IFNβ1)-dependent manner. Chromatin immunoprecipitation assays revealed TRIM16 directly bound the IFNβ1 gene promoter. Low level TRIM16 expression in 91 melanoma patient samples, strongly correlated with lymph node metastasis, and, predicted poor patient prognosis in a separate cohort of 170 melanoma patients with lymph node metastasis. The BRAF inhibitor, vemurafenib, increased TRIM16 protein levels in melanoma cells in vitro, and induced growth arrest in BRAF-mutant melanoma cells in a TRIM16-dependent manner. High levels of TRIM16 in melanoma tissues from patients treated with Vemurafenib correlated with clinical response. Our data, for the first time, demonstrates TRIM16 is a marker of cell migration and metastasis, and a novel treatment target in melanoma.
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ItemA novel compound which sensitizes BRAF wild-type melanoma cells to vemurafenib in a TRIM16-dependent manner(IMPACT JOURNALS LLC, 2016-08-09)There is an urgent need for better therapeutic options for advanced melanoma patients, particularly those without the BRAFV600E/K mutation. In melanoma cells, loss of TRIM16 expression is a marker of cell migration and metastasis, while the BRAF inhibitor, vemurafenib, induces melanoma cell growth arrest in a TRIM16-dependent manner. Here we identify a novel small molecule compound which sensitized BRAF wild-type melanoma cells to vemurafenib. High throughput, cell-based, chemical library screening identified a compound (C012) which significantly reduced melanoma cell viability, with limited toxicity for normal human fibroblasts. When combined with the BRAFV600E/K inhibitor, vemurafenib, C012 synergistically increased vemurafenib potency in 5 BRAFWT and 4 out of 5 BRAFV600E human melanoma cell lines (Combination Index: CI < 1), and, dramatically reduced colony forming ability. In addition, this drug combination was significantly anti-tumorigenic in vivo in a melanoma xenograft mouse model. The combination of vemurafenib and C012 markedly increased expression of TRIM16 protein, and knockdown of TRIM16 significantly reduced the growth inhibitory effects of the vemurafenib and C012 combination. These findings suggest that the combination of C012 and vemurafenib may have therapeutic potential for the treatment of melanoma, and, that reactivation of TRIM16 may be an effective strategy for patients with this disease.