Genomic and Transcriptomic Features of Response to Anti-PD-1 Therapy in Metastatic Melanoma.

PD-1 immune checkpoint blockade provides significant clinical benefits for melanoma patients. We analyzed the somatic mutanomes and transcriptomes of pretreatment melanoma biopsies to identify factors that may influence innate sensitivity or resistance to anti-PD-1 therapy. We find that overall high mutational loads associate with improved survival, and tumors from responding patients are enriched for mutations in the DNA repair gene BRCA2. Innately resistant tumors display a transcriptional signature (referred to as the IPRES, or innate anti-PD-1 resistance), indicating concurrent up-expression of genes involved in the regulation of mesenchymal transition, cell adhesion, extracellular matrix remodeling, angiogenesis, and wound healing. Notably, mitogen-activated protein kinase (MAPK)-targeted therapy (MAPK inhibitor) induces similar signatures in melanoma, suggesting that a non-genomic form of MAPK inhibitor resistance mediates cross-resistance to anti-PD-1 therapy. Validation of the IPRES in other independent tumor cohorts defines a transcriptomic subset across distinct types of advanced cancer. These findings suggest that attenuating the biological processes that underlie IPRES may improve anti-PD-1 response in melanoma and other cancer types.

Preoperative Ultrasound Assessment of Regional Lymph Nodes in Melanoma Patients Does not Provide Reliable Nodal Staging: Results From a Large Multicenter Trial.

OBJECTIVE: To assess whether preoperative ultrasound (US) assessment of regional lymph nodes in patients who present with primary cutaneous melanoma provides accurate staging. BACKGROUND: It has been suggested that preoperative US could avoid the need for sentinel node (SN) biopsy, but in most single-institution reports, the sensitivity of preoperative US has been low. METHODS: Preoperative US data and SNB results were analyzed for patients enrolled at 20 centers participating in the screening phase of the second Multicenter Selective Lymphadenectomy Trial. Excised SNs were histopathologically assessed and considered positive if any melanoma was seen. RESULTS: SNs were identified and removed from 2859 patients who had preoperative US evaluation. Among those patients, 548 had SN metastases. US was positive (abnormal) in 87 patients (3.0%). Among SN-positive patients, 39 (7.1%) had an abnormal US. When analyzed by lymph node basin, 3302 basins were evaluated, and 38 were true positive (1.2%). By basin, the sensitivity of US was 6.6% (95% confidence interval: 4.6-8.7) and the specificity 98.0% (95% CI: 97.5-98.5). Median cross-sectional area of all SN metastases was 0.13 mm2; in US true-positive nodes, it was 6.8 mm2. US sensitivity increased with increasing Breslow thickness of the primary melanoma (0% for ≤1 mm thickness, 11.9% for >4 mm thickness). US sensitivity was not significantly greater with higher trial center volume or with pre-US lymphoscintigraphy. CONCLUSION: In the MSLT-II screening phase population, SN tumor volume was usually too small to be reliably detected by US. For accurate nodal staging to guide the management of melanoma patients, US is not an effective substitute for SN biopsy.

Long-Term Survival after Complete Surgical Resection and Adjuvant Immunotherapy for Distant Melanoma Metastases.

BACKGROUND: This phase III study was undertaken to evaluate the efficacy of an allogeneic whole-cell vaccine (Canvaxin™) plus bacillus Calmette-Guerin (BCG) after complete resection of stage IV melanoma. METHODS: After complete resection of ≤5 distant metastases, patients were randomly assigned to BCG+Canvaxin (BCG/Cv) or BCG+placebo (BCG/Pl). The primary endpoint was overall survival (OS); secondary endpoints were disease-free survival (DFS), and immune response measured by skin test (ClinicalTrials.gov identifier: NCT00052156). RESULTS: Beginning in May 1998, 496 patients were randomized. In April 2005, the Data Safety Monitoring Board recommended stopping enrollment due to a low probability of efficacy. At that time, median OS and 5-year OS rate were 38.6 months and 44.9%, respectively, for BCG/Pl versus 31.4 months and 39.6% in the BCG/Cv group (hazard ratio (HR), 1.18; p = 0.250). Follow-up was extended at several trial sites through March 2010. Median OS and 5-year and 10-year survival was 39.1 months, 43.3 and 33.3%, respectively, for BCG/Pl versus 34.9 months, 42.5 and 36.4%, in the BCG/Cv group (HR 1.053; p = 0.696). Median DFS, 5- and 10-year DFS were 7.6 months, 23.8 and 21.7%, respectively, for BCG/Pl versus 8.5 months, 30.0%, and 30.0%, respectively, for the BCG/Cv group (HR 0.882; p = 0.260). Positive DTH skin testing correlated with increased survival. DISCUSSION: In this, the largest study of postsurgical adjuvant therapy for stage IV melanoma reported to date, BCG/Cv did not improve outcomes over BCG/placebo. Favorable long-term survival among study patients suggests that metastasectomy should be considered for selected patients with stage IV melanoma.

RAF inhibitor resistance is mediated by dimerization of aberrantly spliced BRAF(V600E).

Activated RAS promotes dimerization of members of the RAF kinase family. ATP-competitive RAF inhibitors activate ERK signalling by transactivating RAF dimers. In melanomas with mutant BRAF(V600E), levels of RAS activation are low and these drugs bind to BRAF(V600E) monomers and inhibit their activity. This tumour-specific inhibition of ERK signalling results in a broad therapeutic index and RAF inhibitors have remarkable clinical activity in patients with melanomas that harbour mutant BRAF(V600E). However, resistance invariably develops. Here, we identify a new resistance mechanism. We find that a subset of cells resistant to vemurafenib (PLX4032, RG7204) express a 61-kDa variant form of BRAF(V600E), p61BRAF(V600E), which lacks exons 4-8, a region that encompasses the RAS-binding domain. p61BRAF(V600E) shows enhanced dimerization in cells with low levels of RAS activation, as compared to full-length BRAF(V600E). In cells in which p61BRAF(V600E) is expressed endogenously or ectopically, ERK signalling is resistant to the RAF inhibitor. Moreover, a mutation that abolishes the dimerization of p61BRAF(V600E) restores its sensitivity to vemurafenib. Finally, we identified BRAF(V600E) splicing variants lacking the RAS-binding domain in the tumours of six of nineteen patients with acquired resistance to vemurafenib. These data support the model that inhibition of ERK signalling by RAF inhibitors is dependent on levels of RAS-GTP too low to support RAF dimerization and identify a novel mechanism of acquired resistance in patients: expression of splicing isoforms of BRAF(V600E) that dimerize in a RAS-independent manner.

DCE-MRI analysis methods for predicting the response of breast cancer to neoadjuvant chemotherapy: pilot study findings.

PURPOSE: The purpose of this pilot study is to determine (1) if early changes in both semiquantitative and quantitative DCE-MRI parameters, observed after the first cycle of neoadjuvant chemotherapy in breast cancer patients, show significant difference between responders and nonresponders and (2) if these parameters can be used as a prognostic indicator of the eventual response. METHODS: Twenty-eight patients were examined using DCE-MRI pre-, post-one cycle, and just prior to surgery. The semiquantitative parameters included longest dimension, tumor volume, initial area under the curve, and signal enhancement ratio related parameters, while quantitative parameters included K(trans), v(e), k(ep), v(p), and τ(i) estimated using the standard Tofts-Kety, extended Tofts-Kety, and fast exchange regime models. RESULTS: Our preliminary results indicated that the signal enhancement ratio washout volume and k(ep) were significantly different between pathologic complete responders from nonresponders (P < 0.05) after a single cycle of chemotherapy. Receiver operator characteristic analysis showed that the AUC of the signal enhancement ratio washout volume was 0.75, and the AUCs of k(ep) estimated by three models were 0.78, 0.76, and 0.73, respectively. CONCLUSION: In summary, the signal enhancement ratio washout volume and k(ep) appear to predict breast cancer response after one cycle of neoadjuvant chemotherapy. This observation should be confirmed with additional prospective studies.

Melanoma, version 4.2014.

The NCCN Guidelines for Melanoma provide multidisciplinary recommendations for the management of patients with melanoma. These NCCN Guidelines Insights highlight notable recent updates. Dabrafenib and trametinib, either as monotherapy (category 1) or combination therapy, have been added as systemic options for patients with unresectable metastatic melanoma harboring BRAF V600 mutations. Controversy continues regarding the value of adjuvant radiation for patients at high risk of nodal relapse. This is reflected in the category 2B designation to consider adjuvant radiation following lymphadenectomy for stage III melanoma with clinically positive nodes or recurrent disease.

Adjuvant radiation therapy increases disease-free survival in stage IB Merkel cell carcinoma.

Merkel cell carcinoma (MCC) is a rare and aggressive cutaneous malignancy. Adjuvant radiation increases survival in advanced stages, but efficacy in stage I disease is unknown. A retrospective review included all patients treated for stage I MCC during a 15-year period at Vanderbilt University Medical Center. Among 42 patients, 26 (62%) had a negative sentinel lymph node biopsy (stage IA) and 16 (38%) had clinically negative lymph nodes (stage IB) at the time of resection. Analysis using Cox regression revealed that higher stage and absence of adjuvant radiation are associated with increased disease recurrence (hazard ratio, 6.29; P=0.003 and hazard ratio, 4.69; P=0.013, respectively). Controlling for stage, radiation therapy significantly increased disease-free survival among patients with stage IB disease (P=0.0026) in a log-rank test comparing Kaplan-Meier curves. These findings support adjuvant radiation therapy in stage IB MCC patients with clinically negative lymph nodes who do not undergo sentinel lymph node biopsy.

APOBEC3 deletion polymorphism is associated with breast cancer risk among women of European ancestry.

Copy number variations occur frequently in the genome and are a significant source of human genetic variation accounting for disease. Recently, we discovered a common deletion located in the APOBEC3A and APOBEC3B genes significantly associated with breast cancer in Chinese women. Investigating this locus in other populations would be an expedient way to evaluate the generalizability of the novel finding. We analyzed the APOBEC3 deletion in a large study of 3273 European-ancestry women (including 1671 breast cancer cases and 1602 controls) from the population-based Nashville Breast Health Study. All participants were genotyped using real-time qualitative PCR. Logistic regression was used to derive odds ratios (ORs) and 95% confidence intervals (CIs) for the associations between the deletion polymorphism and breast cancer risk. The APOBEC3 deletion was observed in 12.4% of cases and 10.4% of controls. The deletion was significantly associated with breast cancer risk, with ORs and 95% CIs of 1.21 (1.02-1.43) associated with one-copy deletion and 2.29 (1.04-5.06) associated with two-copy deletion compared with women with no deletion (P for trend = 0.005). The positive association of the APOBEC3 deletion with breast cancer risk was similar for estrogen receptor-positive and estrogen receptor-negative breast cancer and was not modified by known breast cancer risk factors. Results from this study confirmed the association of the APOBEC3 deletion with breast cancer risk among women of European ancestry.