Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC We generated melanoma cell lines resistant to BRAF inhibitors and show that the EGF receptor (EGFR)-SRC family kinase (SFK)-STAT3 signaling pathway was upregulated in these cells. In addition to driving proliferation of resistant cells, this pathway also stimulated invasion and metastasis. EGFR inhibitors cooperated with BRAF inhibitors to block the growth of the resistant cells in vitro and in vivo, and monotherapy with the broad specificity tyrosine kinase inhibitor dasatinib blocked growth and metastasis in vivo. We analyzed a tumor from a BRAF mutant patient with intrinsic resistance to vemurafenib. Vemurafenib treatment induced SFK activation in this tumor and we show that dasatinib blocked its growth and metastasis in immunocompromised mice. Our data shows that BRAF inhibitor-mediated activation of EFGR/SFK/STAT3 signaling can mediate resistance in BRAF mutant melanoma patients. We describe two treatments that appear to overcome this resistance and could deliver therapeutic efficacy in drug-resistant BRAF mutant melanoma patients. Citation Format: Maria R. Girotti, Malin Pedersen, Berta Sanchez-Laorden, Amaya Viros, Samra Turajlic, Dan Niculescu-Duvaz, Alfonso Zambon, John Sinclair, Andrew Hayes, Martin Gore, Caroline Springer, James Larkin, Claus Jorgensen, Richard Marais. Inhibiting EGF receptor or SRC family kinase signaling overcomes BRAF inhibitor resistance in melanoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3404. doi:10.1158/1538-7445.AM2013-3404

Metastatic melanoma is one of the most challenging malignancies to treat and often has a poor outcome. Until recently, systemic treatment options were limited, with poor response rates and no survival advantage. However, the treatment of metastatic melanoma has been revolutionized by developments in targeted therapy and immunotherapy; the BRAF inhibitor, vemurafenib, and anticytotoxic T-lymphocyte antigen 4 antibody, ipilimumab, are the first agents to demonstrate a survival benefit. Despite the success of these treatments, most patients eventually progress, and research into response and resistance mechanisms, rationally designed combination therapies and evaluation of the role of these agents in the adjuvant setting is critically important.

UNLABELLED We generated cell lines resistant to BRAF inhibitors and show that the EGF receptor (EGFR)-SRC family kinase (SFK)-STAT3 signaling pathway was upregulated in these cells. In addition to driving proliferation of resistant cells, this pathway also stimulated invasion and metastasis. EGFR inhibitors cooperated with BRAF inhibitors to block the growth of the resistant cells in vitro and in vivo, and monotherapy with the broad specificity tyrosine kinase inhibitor dasatinib blocked growth and metastasis in vivo. We analyzed tumors from patients with intrinsic or acquired resistance to vemurafenib and observed increased EGFR and SFK activity. Furthermore, dasatinib blocked the growth and metastasis of one of the resistant tumors in immunocompromised mice. Our data show that BRAF inhibitor-mediated activation of EGFR-SFK-STAT3 signaling can mediate resistance in patients with BRAF-mutant melanoma. We describe 2 treatments that seem to overcome this resistance and could deliver therapeutic efficacy in patients with drug-resistant BRAF-mutant melanoma. SIGNIFICANCE Therapies that target the driver oncogenes in cancer can achieve remarkable responses if patients are stratified for treatment. However, as with conventional therapies, patients often develop acquired resistance to targeted therapies, and a proportion of patients are intrinsically resistant and fail to respond despite the presence of an appropriate driver oncogene mutation. We found that the EGFR/SFK pathway mediated resistance to vemurafenib in BRAF -mutant melanoma and that BRAF and EGFR or SFK inhibition blocked proliferation and invasion of these resistant tumors, providing potentially effective therapeutic options for these patients.

Acral melanoma is a rare melanoma subtype with distinct epidemiological, clinical and genetic features. To determine if acral melanoma cell lines are representative of this melanoma subtype, six lines were analysed by whole‐exome sequencing and array comparative genomic hybridisation. We demonstrate that the cell lines display a mutation rate that is comparable to that of published primary and metastatic acral melanomas and observe a mutational signature suggestive of UV‐induced mutagenesis in two of the cell lines. Mutations were identified in oncogenes and tumour suppressors previously linked to melanoma including BRAF, NRAS, KIT, PTEN and TP53, in cancer genes not previously linked to melanoma and in genes linked to DNA repair such as BRCA1 and BRCA2. Our findings provide strong circumstantial evidence to suggest that acral melanoma cell lines and acral tumours share genetic features in common and that these cells are therefore valuable tools to investigate the biology of this aggressive melanoma subtype. Data are available at: http://rock.icr.ac.uk/collaborations/Furney_et_al_2012/.

BRCA1 encodes a tumour suppressor protein that plays pivotal roles in homologous recombination (HR) DNA repair, cell‐cycle checkpoints, and transcriptional regulation. BRCA1 germline mutations confer a high risk of early‐onset breast and ovarian cancer. In more than 80% of cases, tumours arising in BRCA1 germline mutation carriers are oestrogen receptor (ER)‐negative; however, up to 15% are ER‐positive. It has been suggested that BRCA1 ER‐positive breast cancers constitute sporadic cancers arising in the context of a BRCA1 germline mutation rather than being causally related to BRCA1 loss‐of‐function. Whole‐genome massively parallel sequencing of ER‐positive and ER‐negative BRCA1 breast cancers, and their respective germline DNAs, was used to characterize the genetic landscape of BRCA1 cancers at base‐pair resolution. Only BRCA1 germline mutations, somatic loss of the wild‐type allele, and TP53 somatic mutations were recurrently found in the index cases. BRCA1 breast cancers displayed a mutational signature consistent with that caused by lack of HR DNA repair in both ER‐positive and ER‐negative cases. Sequencing analysis of independent cohorts of hereditary BRCA1 and sporadic non‐BRCA1 breast cancers for the presence of recurrent pathogenic mutations and/or homozygous deletions found in the index cases revealed that DAPK3, TMEM135, KIAA1797, PDE4D, and GATA4 are potential additional drivers of breast cancers. This study demonstrates that BRCA1 pathogenic germline mutations coupled with somatic loss of the wild‐type allele are not sufficient for hereditary breast cancers to display an ER‐negative phenotype, and has led to the identification of three potential novel breast cancer genes (ie DAPK3, TMEM135, and GATA4). Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Next generation sequencing has enabled systematic discovery of mutational spectra in cancer samples. Here, we used whole genome sequencing to characterize somatic mutations and structural variation in a primary acral melanoma and its lymph node metastasis. Our data show that the somatic mutational rates in this acral melanoma sample pair were more comparable to the rates reported in cancer genomes not associated with mutagenic exposure than in the genome of a melanoma cell line or the transcriptome of melanoma short-term cultures. Despite the perception that acral skin is sun-protected, the dominant mutational signature in these samples is compatible with damage due to ultraviolet light exposure. A nonsense mutation in ERCC5 discovered in both the primary and metastatic tumors could also have contributed to the mutational signature through accumulation of unrepaired dipyrimidine lesions. However, evidence of transcription-coupled repair was suggested by the lower mutational rate in the transcribed regions and expressed genes. The primary and the metastasis are highly similar at the level of global gene copy number alterations, loss of heterozygosity and single nucleotide variation (SNV). Furthermore, the majority of the SNVs in the primary tumor were propagated in the metastasis and one nonsynonymous coding SNV and one splice site mutation appeared to arise de novo in the metastatic lesion.

TPS229 Background: Recent studies have indicated that KIT mutations occur in approximately 20% of acral and mucosal melanomas (Curtin, al. 2006; Beadling, et al. 2008). Several case reports have shown that KIT mutated melanomas can respond to treatment with KIT inhibitors (Hodi et al. 2008; Lutzky et al. 2008; Quintas-Cardama et al. 2008; Handolias et al. 2010; Itoh, et al. 2010; Satzger et al. 2010; Terheyden et al. 2010; Woodman and Davies 2010) suggesting that such tumours critically depend on upregulated KIT signalling. Nilotinib, which potently inhibits the tyrosine kinase activity of BCR-ABL and KIT, has been evaluated in patients with advanced KIT mutated GIST and has shown clinical efficacy at well tolerated doses (Demetri et al. 2009; Montemurro et al. 2009; Schlemmer et al. 2010). METHODS NICAM is a single arm 2-stage open label phase II study of nilotinib in KIT mutated advanced mucosal or acral melanoma. Patients with KIT mutations known to confer resistance to nilotinib are excluded. The primary objective in this feasibility study is to evaluate the efficacy of nilotinib in KIT mutated advanced mucosal and acral melanoma with a primary endpoint of progression free survival at 6 months. Secondary endpoints include response rate at 12 weeks; overall survival; toxicity of treatment; correlation between the response to nilotinib and KIT genotype, KIT gene copy number and KIT expression. In addition, the following will be explored: 1. Suppression of phosphorylation of KIT and downstream pathways on day 15 tumour biopsies; 2. Possible mechanisms of resistance by analysis of biopsies obtained at disease progression; 3. The use of circulating tumour DNA for non-invasive KIT mutational testing; 4. Genetic lesions that potentially cooperate with oncogenic KIT in melanoma (using Next Generation Sequencing). All patients are treated until disease progression or unacceptable toxicity. If 2 or more of the first 9 patients are progression free at 6 months, patient entry will continue into the second stage until a total of 24 patients have been recruited. To date, 45 patients have been registered and screened for KIT mutation and 5 patients have entered the study.

We describe a case of generalized melanosis and melanuria in a patient with metastatic melanoma and review the pathogenesis and prognostic implications of this phenomenon. A 62-year-old-man with Fitzpatrick skin type II presented with a 3-month history of changes in a mole on his back. Histological examination of a biopsy found an incompletely excised superficial spreading melanoma (Breslow thickness 9 mm, Clark level V, nonulcerated, perineural and perivascular invasion, mitotic rate 21 ⁄ mm) with microsatellite deposits at the deep margin. A whole-body positron emission and computed tomography (PET-CT) scan revealed no evidence of distant metastatic disease, and baseline liver profile, full blood count and lactate dehydrogenase (LDH) level were normal. A 20-mm wide local excision down to the fascia was performed and reported as an incompletely excised in-transit metastasis. Fourteen months after the initial surgery, the patient presented with a 3-month history of right-sided chest pain, and diffuse slate-grey hyperpigmentation of the PD

We present a proof-of-concept study to assess whether deformable registration followed by tissue classification using machine learning (ML) is an effective method for the delineation of liver metastases in whole-body diffusion-weighted imaging (WB-DWI). Deformable atlas-based registration achieves good quality delineation of the liver (Dice coefficient > 70%) and out of three ML models random forest achieved the best F-1 measure for segmenting disease within the liver.