Christopher K. Bichakjian

Primary cilia can both mediate and suppress Hedgehog pathway–dependent tumorigenesis

Primary cilia are present on most mammalian cells and are implicated in transducing Hedgehog (Hh) signals during development; however, the prevalence of cilia on human tumors remains unclear, and the role of cilia in cancer has not been examined. Here we show that human basal cell carcinomas (BCCs) are frequently ciliated, and we test the role of cilia in BCC by conditionally deleting Kif3a (encoding kinesin family member 3A) or Ift88 (encoding intraflagellar transport protein 88), genes required for ciliogenesis, in two Hh pathway–dependent mouse tumor models. Ciliary ablation strongly inhibited BCC-like tumors induced by an activated form of Smoothened. In contrast, removal of cilia accelerated tumors induced by activated Gli2, a transcriptional effector of Hh signaling. These seemingly paradoxical effects are consistent with a dual role for cilia in mediating both the activation and the repression of the Hh signaling pathway. Our findings demonstrate that cilia function as unique signaling organelles that can either mediate or suppress tumorigenesis depending on the nature of the oncogenic initiating event.

Merkel Cell Carcinoma: Critical Review With Guidelines for Multidisciplinary Management

Merkel cell carcinoma (MCC) is a relatively rare cutaneous malignancy that occurs predominantly in the older white population. The incidence of MCC appears to have tripled during the past 20 years; an increase that is likely to continue because of the growing number of older Americans. The pathogenesis of MCC remains largely unknown. However, ultraviolet radiation and immunosuppression are likely to play a significant pathogenetic role. Many questions currently remain unanswered regarding the biologic behavior and optimal treatment of MCC. Large, prospective, randomized studies are not available and are unlikely to be performed because of the rarity of the disease. The objective of this review was to provide a comprehensive reference for MCC based on a critical evaluation of the current data. The authors investigated the importance of sentinel lymph node biopsy as a staging tool for MCC to assess the status of the regional lymph node basin and to determine the need for additional therapy to the lymph node basin. In an attempt to standardize prospective data collection with the intention to define prognostic indicators, the authors also present histopathologic profiles for primary MCC and sentinel lymph nodes. The controversies regarding the appropriate surgical approach to primary MCC, the use of adjuvant radiation therapy, and the effectiveness of adjuvant chemotherapy were examined critically. Finally, the authors have provided treatment guidelines based on the available evidence and their multidisciplinary experience. Cancer 2007.

Guidelines of care for the management of primary cutaneous melanoma.

The incidence of primary cutaneous melanoma has been increasing dramatically for several decades. Melanoma accounts for the majority of skin cancer-related deaths, but treatment is nearly always curative with early detection of disease. In this update of the guidelines of care, we will discuss the treatment of patients with primary cutaneous melanoma. We will discuss biopsy techniques of a lesion clinically suspicious for melanoma and offer recommendations for the histopathologic interpretation of cutaneous melanoma. We will offer recommendations for the use of laboratory and imaging tests in the initial workup of patients with newly diagnosed melanoma and for follow-up of asymptomatic patients. With regard to treatment of primary cutaneous melanoma, we will provide recommendations for surgical margins and briefly discuss nonsurgical treatments. Finally, we will discuss the value and limitations of sentinel lymph node biopsy and offer recommendations for its use in patients with primary cutaneous melanoma.

Hedgehog‐EGFR cooperation response genes determine the oncogenic phenotype of basal cell carcinoma and tumour‐initiating pancreatic cancer cells

Inhibition of Hedgehog (HH)/GLI signalling in cancer is a promising therapeutic approach. Interactions between HH/GLI and other oncogenic pathways affect the strength and tumourigenicity of HH/GLI. Cooperation of HH/GLI with epidermal growth factor receptor (EGFR) signalling promotes transformation and cancer cell proliferation in vitro. However, the in vivo relevance of HH‐EGFR signal integration and the critical downstream mediators are largely undefined. In this report we show that genetic and pharmacologic inhibition of EGFR signalling reduces tumour growth in mouse models of HH/GLI driven basal cell carcinoma (BCC). We describe HH‐EGFR cooperation response genes including SOX2, SOX9, JUN, CXCR4 and FGF19 that are synergistically activated by HH‐EGFR signal integration and required for in vivo growth of BCC cells and tumour‐initiating pancreatic cancer cells. The data validate EGFR signalling as drug target in HH/GLI driven cancers and shed light on the molecular processes controlled by HH‐EGFR signal cooperation, providing new therapeutic strategies based on combined targeting of HH‐EGFR signalling and selected downstream target genes.

Features Predicting Sentinel Lymph Node Positivity in Merkel Cell Carcinoma

PURPOSE Merkel cell carcinoma (MCC) is a relatively rare, potentially aggressive cutaneous malignancy. We examined the clinical and histologic features of primary MCC that may correlate with the probability of a positive sentinel lymph node (SLN). METHODS Ninety-five patients with MCC who underwent SLN biopsy at the University of Michigan were identified. SLN biopsy was performed on 97 primary tumors, and an SLN was identified in 93 instances. These were reviewed for clinical and histologic features and associated SLN positivity. Univariate associations between these characteristics and a positive SLN were tested for by using either the χ(2) or the Fishers exact test. A backward elimination algorithm was used to help create a best multiple variable model to explain a positive SLN. RESULTS SLN positivity was significantly associated with the clinical size of the lesion, greatest horizontal histologic dimension, tumor thickness, mitotic rate, and histologic growth pattern. Two competing multivariate models were generated to predict a positive SLN. The histologic growth pattern was present in both models and combined with either tumor thickness or mitotic rate. CONCLUSION Increasing clinical size, increasing tumor thickness, increasing mitotic rate, and infiltrative tumor growth pattern were significantly associated with a greater likelihood of a positive SLN. By using the growth pattern and tumor thickness model, no subgroup of patients was predicted to have a lower than 15% to 20% likelihood of a positive SLN. This suggests that all patients presenting with MCC without clinical evidence of regional lymph node disease should be considered for SLN biopsy.

The Distinctive Mutational Spectra of Polyomavirus-Negative Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is a rare but highly aggressive cutaneous neuroendocrine tumor. Merkel cell polyomavirus (MCPyV) may contribute to tumorigenesis in a subset of tumors via inhibition of tumor suppressors such as retinoblastoma (RB1) by mutated viral T antigens, but the molecular pathogenesis of MCPyV-negative MCC is largely unexplored. Through our MI-ONCOSEQ precision oncology study, we performed integrative sequencing on two cases of MCPyV-negative MCC, as well as a validation cohort of 14 additional MCC cases (n = 16). In addition to previously identified mutations in TP53, RB1, and PIK3CA, we discovered activating mutations of oncogenes, including HRAS and loss-of-function mutations in PRUNE2 and NOTCH family genes in MCPyV-negative MCC. MCPyV-negative tumors also displayed high overall mutation burden (10.09 ± 2.32 mutations/Mb) and were characterized by a prominent UV-signature pattern with C > T transitions comprising 85% of mutations. In contrast, mutation burden was low in MCPyV-positive tumors (0.40 ± 0.09 mutations/Mb) and lacked a UV signature. These findings suggest a potential ontologic dichotomy in MCC, characterized by either viral-dependent or UV-dependent tumorigenic pathways.

Sentinel lymph node biopsy is accurate and prognostic in head and neck melanoma

Sentinel lymph node biopsy (SLNB) has emerged as a widely used staging procedure for cutaneous melanoma. However, debate remains around the accuracy and prognostic implications of SLNB for cutaneous melanoma arising in the head and neck, as previous reports have demonstrated inferior results to those in nonhead and neck regions. Through the largest single‐institution series of head and neck melanoma patients, the authors set out to demonstrate that SLNB accuracy and prognostic value in the head and neck region are comparable to other sites.

Distinct Gene Expression Profiles of Viral- and Nonviral-Associated Merkel Cell Carcinoma Revealed by Transcriptome Analysis

Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine tumor with high mortality rates. Merkel cell polyomavirus (MCPyV), identified in the majority of MCC, may drive tumorigenesis via viral T antigens. However, mechanisms underlying pathogenesis in MCPyV-negative MCC remain poorly understood. To nominate genes contributing to pathogenesis of MCPyV-negative MCC, we performed DNA microarray analysis on 30 MCCs. MCPyV status of MCCs was determined by PCR for viral DNA and RNA. 1593 probe-sets were differentially expressed between MCPyV-negative and -positive MCC, with significant differential expression defined as at least 2-fold change in either direction and p-value of ≤ 0.05. MCPyV-negative tumors showed decreased RB1 expression, whereas MCPyV-positive tumors were enriched for immune response genes. Validation studies included immunohistochemistry demonstration of decreased RB protein expression in MCPyV-negative tumors and increased peritumoral CD8+ T lymphocytes surrounding MCPyV-positive tumors. In conclusion, our data suggest that loss of RB1 expression may play an important role in tumorigenesis of MCPyV-negative MCC. Functional and clinical validation studies are needed to determine whether this tumor suppressor pathway represents an avenue for targeted therapy.

Relationships among primary tumor size, number of involved nodes, and survival for 8044 cases of Merkel cell carcinoma

BACKGROUND The effects of primary tumor size on nodal involvement and of number of involved nodes on survival have not, to our knowledge, been examined in a national database of Merkel cell carcinoma (MCC). OBJECTIVE We sought to analyze a retrospective cohort of patients with MCC from the largest US national database to assess the relationships between these clinical parameters and survival. METHODS A total of 8044 MCC cases in the National Cancer Data Base were analyzed. RESULTS There was a 14% risk of regional nodal involvement for 0.5-cm tumors that increased to 25% for 1.7-cm (median-sized) tumors and to more than 36% for tumors 6 cm or larger. The number of involved nodes was strongly predictive of survival (0 nodes, 76% 5-year relative survival; 1 node, 50%; 2 nodes, 47%; 3-5 nodes, 42%; and ≥6 nodes, 24%; P < .0001 for trend). Younger and/or male patients were more likely to undergo pathological nodal evaluation. LIMITATIONS The National Cancer Data Base does not capture disease-specific survival. Hence, relative survival was calculated by comparing overall survival with age- and sex-matched US population data. CONCLUSION Pathologic nodal evaluation should be considered even for patients with small primary MCC tumors. The number of involved nodes is strongly predictive of survival and may help improve prognostic accuracy and management.

Melanoma, version 4.2014: Featured updates to the NCCN guidelines

The NCCN Guidelines for Melanoma provide multidisciplinary recommendations on the clinical management of patients with melanoma. This NCCN Guidelines Insights report highlights notable recent updates. Foremost of these is the exciting addition of the novel agents ipilimumab and vemurafenib for treatment of advanced melanoma. The NCCN panel also included imatinib as a treatment for KIT-mutated tumors and pegylated interferon alfa-2b as an option for adjuvant therapy. Also important are revisions to the initial stratification of early-stage lesions based on the risk of sentinel lymph node metastases, and revised recommendations on the use of sentinel lymph node biopsy for low-risk groups. Finally, the NCCN panel reached clinical consensus on clarifying the role of imaging in the workup of patients with melanoma.