Targeting mutant NRAS signaling pathways in melanoma.

Cutaneous melanoma is a devastating form of skin cancer and its incidence is increasing faster than any other preventable cancer in the United States. The mutant NRAS subset of melanoma is more aggressive and associated with poorer outcomes compared to non-NRAS mutant melanoma. The aggressive nature and complex molecular signaling conferred by this transformation has evaded clinically effective treatment options. This review examines the major downstream effectors of NRAS relevant in melanoma and the associated advances made in targeted therapies that focus on these effector pathways. We outline the history of MEK inhibition in mutant NRAS melanoma and recent advances with newer MEK inhibitors. Since MEK inhibitors will likely be optimized when combined with other targeted therapies, we focus on recently identified targets that can be used in combination with MEK inhibitors.

Acne Scarring-Pathogenesis, Evaluation, and Treatment Options.

Acne vulgaris is a ubiquitous problem affecting 80 percent of people ages 11 to 30 years, with many patients experiencing some degree of scarring. This review focuses on atrophic scars, the most common type of acne scar. We briefly address the cellular sequelae that lead to scar formation and the initial evaluation of patients with acne scars. We then discuss an algorithmic approach to the treatment of acne scarring based on the classification of scars into erythematous and atrophic types. Lastly, we discuss the future treatment of acne scars and ongoing clinical trials.

MIG6 Is MEK Regulated and Affects EGF-Induced Migration in Mutant NRAS Melanoma.

Activating mutations in neuroblastoma RAS viral oncogene homolog (NRAS) are frequent driver events in cutaneous melanoma. NRAS is a guanosine triphosphate-binding protein whose most well-characterized downstream effector is RAF, leading to activation of mitogen-activated protein kinase (MEK)-extracellular signal-regulated protein kinase 1/2 signaling. Although there are no Food and Drug Administration-approved targeted therapies for melanoma patients with a primary mutation in NRAS, one form of targeted therapy that has been explored is MEK inhibition. In clinical trials, MEK inhibitors have shown disappointing efficacy in mutant NRAS patients, the reasons for which are unclear. To explore the effects of MEK inhibitors in mutant NRAS melanoma, we used a high-throughput reverse-phase protein array platform to identify signaling alterations. Reverse-phase protein array analysis of phospho-proteomic changes in mutant NRAS melanoma in response to trametinib indicated a compensatory increase in v-akt murine thymoma viral oncogene homolog signaling and decreased expression of mitogen-inducible gene 6 (MIG6), a negative regulator of epidermal growth factor receptor/v-erb-b2 erythroblastic leukemia viral oncogene homolog receptors. MIG6 expression did not alter the growth or survival properties of mutant NRAS melanoma cells. Rather, we identified a role for MIG6 as a negative regulator of epidermal growth factor-induced signaling and cell migration and invasion. In MEK-inhibited cells, further depletion of MIG6 increased migration and invasion, whereas MIG6 expression decreased these properties. Therefore, a decrease in MIG6 may promote the migration and invasiveness of MEK-inhibited mutant NRAS melanoma, especially in response to epidermal growth factor stimulation.

RAC1 P29S regulates PD-L1 expression in melanoma.

Whole exome sequencing of cutaneous melanoma has led to the detection of P29 mutations in RAC1 in 5-9% of samples, but the role of RAC1 P29 mutations in melanoma biology remains unclear. Using reverse phase protein array analysis to examine the changes in protein/phospho-protein expression, we identified cyclin B1, PD-L1, Ets-1, and Syk as being selectively upregulated with RAC1 P29S expression and downregulated with RAC1 P29S depletion. Using the melanoma patient samples in TCGA, we found PD-L1 expression to be significantly increased in RAC1 P29S patients compared to RAC1 WT as well as other RAC1 mutants. The finding that PD-L1 is upregulated suggests that oncogenic RAC1 P29S may promote suppression of the antitumor immune response. This is a new insight into the biological function of RAC1 P29S mutations with potential clinical implications as PD-L1 is a candidate biomarker for increased benefit from treatment with anti-PD1 or anti-PD-L1 antibodies.

Targeting TBK1 inhibits migration and resistance to MEK inhibitors in mutant NRAS melanoma.

UNLABELLED: Melanoma is a devastating form of skin cancer with limited therapeutic options. Fifteen to 20% of patients with melanoma have an activating mutation in the GTPase, NRAS. The major downstream effectors of RAS are RAFs (ARAF, BRAF, and CRAF), phosphoinositide 3-kinase (PI3K), and the Ral guanine exchange factors (RalGEF). TANK-binding kinase 1 (TBK1) is an atypical IκB kinase family member that acts downstream of RalGEFs. Whereas many studies have analyzed RAF and PI3K signaling in mutant NRAS melanoma, the role of RalGEF/Ral is understudied and TBK1 has not been examined. To address this, TBK1 was modulated with knockdown approaches and targeted therapies to determine the role of TBK1 in motility, apoptosis, and signaling. In melanoma, NRAS overexpression increased TBK1 phosphorylation. TBK1 depletion inhibited migration and invasion, whereas its constitutive overexpression led to an increase in invasion. In three-dimensional systems that mimic the dermal microenvironment, TBK1 depletion or inhibition cooperated with MEK inhibitors to promote apoptosis, particularly in the context of MEK-insensitive mutant NRAS. This effect was absent in melanoma cells that are wild-type for NRAS. These results suggest the utility of TBK1 inhibitors as part of a treatment regimen for patients with mutant NRAS melanoma, for whom there are no current effective therapies. IMPLICATIONS: TBK1 promotes the malignant properties of NRAS-mutant melanoma and its targeting, in combination with MEK, promotes apoptosis, thus providing a potential novel targeted therapeutic option.

Combined Inhibition of Epidermal Growth Factor Receptor and Cyclooxygenase-2 as a Novel Approach to Enhance Radiotherapy.

Targeting epidermal growth factor receptor (EGFR) is a promising approach to increasing radiosensitivity of head and neck cancers but treatment resistance remains an important clinical problem. We hypothesize that combined EGFR and cyclooxygenase-2 (COX-2) inhibition, using small molecule inhibitors erlotinib and celecoxib, respectively would further increase the antitumor activity of radiotherapy. The effects of combinations of celecoxib, erlotinib and ionizing radiation (IR) on cell growth, cell cycle progression and apoptosis of head and neck cancer cell lines were assessed in vitro by cell viability, clonogenic survival, flow cytometry and Annexin V assays and in vivo. The effects of celecoxib, erlotinib and IR on primary and downstream molecular targets were analyzed by immunoblotting & ELISA assays. Compared to single or double agent approaches, concurrent celecoxib, erlotinib and IR was the most effective regimen at reducing clonogenic survival, increasing apoptosis and inhibiting tumor growth in vivo. Concurrent treatment with celecoxib and erlotinib ± IR inhibited multiple prosurvival proteins including p-ERK1/2, p-EGFR, p-AKT, p-STAT3, COX-2 and PGE-2. The combination of celecoxib, erlotinib and IR is a promising strategy to overcoming resistance to combined EGFR inhibition and IR alone.

HPV-induced oropharyngeal cancer, immune response and response to therapy.

Approximately 25% of head and neck squamous cell carcinoma (HNSCC) worldwide are associated with high-risk human papillomaviruses (HPV). HPV-positive HNSCCs have a more favorable outcome and greater response to therapy. While chronic HPV infection allows for the evolution of immune evasion mechanisms, viral antigens can still elicit an immune response. Moreover, a robust lymphocytic response is associated with better prognosis in a variety of tumor types including head and neck cancer. This article outlines several mechanisms whereby the observed improved response of HPV-positive tumors to radiotherapy may be related to enhancement of the immune response following radiotherapy.

The diagnostic and prognostic utility of positron emission tomography/computed tomography-based follow-up after radiotherapy for head and neck cancer.

BACKGROUND: The detection of subclinical head and neck cancer recurrence or a second primary tumor may improve survival. In the current study, the authors investigated the clinical value of a follow-up program incorporating serial (18)F-fluorodeoxyglucose-positron emission tomography integrated with computed tomography (PET/CT) in the detection of recurrent disease in patients with head and neck cancer. METHODS: A total of 240 PET/CT scans were reviewed in 80 patients with head and neck cancer who were treated with radiotherapy (RT) from July, 2005 through August, 2007. All patients were followed with clinical examination, PET/CT, and correlative imaging for a minimum of 11 months (median follow-up, 21 months). RESULTS: The sensitivity, specificity, and positive and negative predictive values of PET/CT-based follow-up for detecting locoregional recurrence were 92%, 82%, 42%, and 98%, respectively. Corresponding values for distant metastases or second primary tumors were 93%, 96%, 81%, and 98%, respectively. Eight patients (10%) developed disease recurrences or second primary tumors that were amenable to salvage surgery with negative surgical margins. The 2-year progression-free survival and 2-year overall survival rates were significantly different between patients who had a negative and those with a positive PET/CT result within 6 months of the completion of RT (93% vs 30% [P<.001] and 100% vs 32% [P<.001], respectively). CONCLUSIONS: Although post-therapy follow-up using PET/CT is reportedly associated with a high false-positive rate in the irradiated head and neck, PET/CT appears to be a highly sensitive technique for the detection of recurrent disease. Furthermore, negative PET/CT results within 6 months of the completion of RT offer significant prognostic value.

Phase 1 study of concurrent sunitinib and image-guided radiotherapy followed by maintenance sunitinib for patients with oligometastases: acute toxicity and preliminary response.

BACKGROUND: To determine the safety and maximum-tolerated dose of concurrent sunitinib and image-guided radiotherapy (IGRT) followed by maintenance sunitinib in oligometastastic patients. METHODS: Eligible patients had 1 to 5 sites of metastatic cancer measuring