A phase 2 trial of dasatinib in advanced melanoma

Combination of MEK and SRC inhibition suppresses melanoma cell growth and invasion

The RAS-RAF-MEK-ERK pathway is deregulated in over 90% of malignant melanomas, and targeting MEK as a central kinase of this pathway is currently tested in clinical trials. However, dose-limiting side effects are observed, and MEK inhibitors that sufficiently reduce ERK activation in patients show a low clinical response. Apart from dose limitations, a reason for the low response to MEK targeting drugs is thought to be the upregulation of counteracting signalling cascades as a direct response to MEK inhibition. Therefore, understanding the biology of melanoma cells and the effects of MEK inhibition on these cells will help to identify new combinatorial approaches that are more potent and allow for lower concentrations of the drug being used. We have discovered that in melanoma cells MEK inhibition by selumetinib (AZD6244, ARRY-142886) or PD184352, while efficiently suppressing proliferation, stimulates increased invasiveness. Inhibition of MEK suppresses actin-cortex contraction and increases integrin-mediated adhesion. Most importantly, and surprisingly, MEK inhibition results in a significant increase in matrix metalloproteases (MMP)-2 and membrane-type 1-MMP expression. All together, MEK inhibition in melanoma cells induces a 'mesenchymal' phenotype that is characterised by protease-driven invasion. This mode of invasion is dependent on integrin-mediated adhesion, and because SRC kinases are the main regulators of this process, the SRC kinase inhibitor, saracatinib (AZD0530), completely abolished the MEK inhibitor-induced invasion. Moreover, the combination of saracatinib and selumetinib effectively suppressed the growth and invasion of melanoma cells in a 3D environment, suggesting that combined inhibition of MEK and SRC is a promising approach to improve the efficacy of targeting the ERK/MAP kinase pathway in melanoma.

Current status of primary malignant melanoma of the esophagus: clinical features, pathology, management and prognosis

Primary malignant melanoma of the esophagus (PMME) is a rare disease with an extremely poor prognosis. Up to 2011, approximately 300 cases had been reported worldwide. The average age of onset is 60.5 years old, with a prevalence of males (2:1). A typical finding of PMME is a lobular or polyploid, well-circumscribed and pigmented tumor, partly covered with normal mucosa. PMME represents various colors depending on its melanin quantity and commonly coexists with intramural metastases, melanocytosis or melanoma in situ. The tumor is located from the middle to lower thoracic esophagus. The accuracy of diagnosis from biopsy is approximately 80%, because many cases are misdiagnosed as a poorly differentiated carcinoma because of the absence of melanin granules. A definite diagnosis was made by immunohistochemical examination with positive results of S100 protein, HMB45 and neuron-specific enolase. PMME has a highly metastatic potential, and the incidence of distant metastasis at the initial diagnosis is around 40-80%. A metastatic tumor from cutaneous malignant melanoma is another pigmented esophageal tumor to be considered when making the differential diagnosis for PMME. Junctional activity with melanotic cells in the adjacent epithelium and the presence of in situ melanoma and/or a satellite tumor without a previous history of cutaneous melanoma are definitive. Most of the reported patients were treated with radical esophagectomy, which is believed to be an effective approach for localized PMME. Five-year survival rates have been achieved in 37% recently, while adjuvant therapy has not been proven to increase overall survival but plays a palliative role.

Profile of ipilimumab and its role in the treatment of metastatic melanoma

Melanoma is an immunogenic cancer. However, the ability of the immune system to eradicate melanoma tumors is affected by intrinsic negative regulatory mechanisms. Multiple immune-modulatory therapies are currently being developed to optimize the immune response to melanoma tumors. Two recent Phase III studies using the monoclonal antibody ipilimumab, which targets the cytotoxic T-lymphocyte antigen (CTLA-4), a negative regulator of T-cell activation, have demonstrated improvement in overall survival of metastatic melanoma patients. This review highlights the clinical trial data that supports the efficacy of ipilimumab, the immune-related response criteria used to evaluate clinical response, and side-effect profile associated with ipilimumab treatment.

Phase I clinical trial of the Src inhibitor dasatinib with dacarbazine in metastatic melanoma

Background:

Src inhibitors sensitise melanoma cells to chemotherapy in preclinical models. The combination of dasatinib and dacarbazine was tested in a phase I trial in melanoma.

Methods:

Patients had ECOG performance status 0–2 and normal organ function. Dacarbazine was administered on day 1 and dasatinib on day 2 through 19 of each 21-day cycle. Both were escalated from 50 mg b.i.d. of dasatinib and 800 mg m⁻² of dacarbazine. Available pre-treatment biopsies were sequenced for BRAF, NRAS, and C-Kit mutations.

Results:

Dose-limiting toxicity was reached at dasatinib 70 mg b.i.d./dacarbazine 1000 mg m⁻², and was predominantly haematological. In 29 patients receiving dasatinib 70 mg b.i.d., the objective response rate (ORR) was 13.8%, the clinical benefit rate (ORR+SD) was 72.4%, the 6-month progression-free survival (PFS) was 20.7%, and the 12-month overall survival (OS) was 34.5%. Two out of three patients who were wild type for BRAF, NRAS, and c-KIT mutations had confirmed partial responses, and one had a minor response.

Conclusion:

The recommended phase II dose is dasatinib70 mg b.i.d with dacarbazine 800 mg m⁻². PFS and OS data for dasatinib at 70 mg b.i.d. with dacarbazine compared favourably with historical controls. Preliminary data support evaluating tumour mutation status further as a biomarker of response.

Melanoma update: diagnostic and prognostic factors that can effectively shape and personalize management

Routine light microscopy remains a powerful tool to diagnose, stage and prognose melanoma. Although it is very economical and efficient, it requires a significant level of expertise and, in difficult cases the final diagnosis is affected by subjective interpretation. Fortunately, new insights into the genomic aberrations characteristic of melanoma, coupled with ancillary studies, are further refining evaluation and management allowing for more confident diagnosis, more accurate staging and the selection of targeted therapy. In this article, we review the standard of care and new updates including four probe FISH, the 2009 American Joint Commission on Cancer staging of melanoma and mutant testing of melanoma, which will be crucial for targeted therapy of metastatic melanoma.

HOXC11-SRC-1 regulation of S100beta in cutaneous melanoma: new targets for the kinase inhibitor dasatinib

Background:

Cutaneous melanoma is an aggressive disease. S100beta is an established biomarker of disease progression; however, the mechanism of its regulation in melanoma is undefined.

Methods:

Expression of HOXC11 and SRC-1 was examined by immunohistochemistry and immunofluorescence. Molecular and cellular techniques were used to investigate regulation of S100beta, including, western blot, qPCR, ChIP and migration assays.

Results:

Expression levels of the transcription factor HOXC11 and its coactivator SRC-1 were significantly elevated in malignant melanoma in comparison with benign nevi (P<0.001 and P=0.017, respectively, n=80), and expression of HOXC11 and SRC-1 in the malignant tissue associated with each other (P<0.001). HOXC11 recruitment to the promoter of S100beta was observed in the primary melanoma cell line SKMel28. S100beta expression was found to be dependant on both HOXC11 and SRC-1. Treatment with the Src/Abl inhibitor, dasatinib, reduced HOXC11–SRC-1 interaction and prevented recruitment of HOXC11 to the S100beta promoter. Dasatinib inhibited both mRNA and protein levels of S100beta and reduced migration of the metastatic cell line MeWo.

Conclusion:

We have defined a signalling mechanism regulating S100beta in melanoma, which can be modulated by dasatinib. Profiling patients for expression of key markers of this network has the potential to increase the efficacy of dasatinib treatment.