Extensive Perineural Invasion vs Nerve Caliber to Assess Cutaneous Squamous Cell Carcinoma Prognosis

Importance

Perineural invasion (PNI) is an adverse risk feature in cutaneous squamous cell carcinoma (CSCC) that affects patient prognosis and disease management. However, research comparing different PNI patterns on patient outcomes is limited.

Objective

To compare 4 assessments of PNI in CSCC, their associations with poor outcomes, and implications for their inclusion in the Brigham and Women's Hospital (BWH) staging system.

Design, Setting, and Participants

This retrospective cohort study was performed at a single tertiary care institution and compared 4 PNI assessments: nerve caliber, number of involved nerves per section, PNI maximal depth, and PNI location with respect to tumor. Patients with primary, localized, invasive CSCC with PNI diagnosed between January 1, 2000, and December 31, 2017, were identified via an electronic in-house database. Available pathology slides were secondarily reviewed by study authors. Relevant patient and tumor characteristics and outcomes were abstracted from the medical record. Data analysis was performed between September 6 and October 20, 2022.

Main Outcomes and Measures

Risks of recurrence, disease-specific death, and a composite end point (any poor outcome) were calculated via multivariable stepwise Fine and Gray competing-risks regression. Considered revisions to the BWH staging system were assessed via receiver operating characteristic curves and test characteristics.

Results

This study included 140 patients with CSCC, with a mean (SD) age of 75.1 (11.2) years. More than half of the patients were men (93 [66.4%]), and most identified as White (132 [94.3%]). Of the 4 PNI assessments studied, only involvement of multiple nerves was associated with poor outcomes. Perineural invasion of 5 or more distinct nerves (extensive PNI [ePNI]) was independently associated with local recurrence (subhazard ratio [SHR], 13.83 [95% CI, 3.50-54.62]; P < .001), disease-specific death (SHR, 6.20 [95% CI, 1.59-24.21]; P = .009), and any poor outcome (SHR, 10.21 [95% CI, 2.88-36.15]; P < .001). A revised BWH staging system with substitution of ePNI for large-caliber PNI resulted in improved area under the curve and test characteristics compared with current BWH staging criteria that use nerve caliber as the measure of PNI.

Conclusions and Relevance

The findings of this cohort study suggest that ePNI is the best prognostic measure of PNI. Because ePNI obviated the need for a micrometer and had superior prognostic capacity to nerve caliber in this cohort, ePNI should be considered for inclusion in CSCC tumor staging. Inclusion of ePNI as a high-risk factor in CSCC staging systems may optimize patient selection for primary treatment and adjuvant interventions.

Clinical and molecular characterization of virus-positive and virus-negative Merkel cell carcinoma

BACKGROUND

Merkel cell carcinoma (MCC) is a highly aggressive neuroendocrine carcinoma of the skin caused by either the integration of Merkel cell polyomavirus (MCPyV) and expression of viral T antigens or by ultraviolet-induced damage to the tumor genome from excessive sunlight exposure. An increasing number of deep sequencing studies of MCC have identified significant differences between the number and types of point mutations, copy number alterations, and structural variants between virus-positive and virus-negative tumors. However, it has been challenging to reliably distinguish between virus positive and UV damaged MCC.

METHODS

In this study, we assembled a cohort of 71 MCC patients and performed deep sequencing with OncoPanel, a clinically implemented, next-generation sequencing assay targeting over 400 cancer-associated genes. To improve the accuracy and sensitivity for virus detection compared to traditional PCR and IHC methods, we developed a hybrid capture baitset against the entire MCPyV genome and software to detect integration sites and structure.

RESULTS

Sequencing from this approach revealed distinct integration junctions in the tumor genome and generated assemblies that strongly support a model of microhomology-initiated hybrid, virus-host, circular DNA intermediate that promotes focal amplification of host and viral DNA. Using the clear delineation between virus-positive and virus-negative tumors from this method, we identified recurrent somatic alterations common across MCC and alterations specific to each class of tumor, associated with differences in overall survival. Finally, comparing the molecular and clinical data from these patients revealed a surprising association of immunosuppression with virus-negative MCC and significantly shortened overall survival.

CONCLUSIONS

These results demonstrate the value of high-confidence virus detection for identifying molecular mechanisms of UV and viral oncogenesis in MCC. Furthermore, integrating these data with clinical data revealed features that could impact patient outcome and improve our understanding of MCC risk factors.

Topographical Evaluation of Penile Lichen Sclerosus Reveals a Lymphocytic Depleted Variant, Preferentially Associated With Neoplasia: A Report of 200 Cases

Since the seminal study of Hart and Helwig in 1975, there are few detailed pathological studies of lichen sclerosus (LS). The aims of this study were to provide a detailed histopathological description of penile LS, as well as to explore its relationship with penile intraepithelial neoplasia (PeIN) or invasive carcinoma. We evaluated 200 patients and designed a topographical approach for the histological evaluation focusing in alterations of the following anatomical layers: squamous epithelium, lamina propria, dartos, and corpus spongiosum. We documented the quantity and topographical location of stromal lymphocytes. The prevalent lesions found were epithelial hyperplasia, atrophy, PeIN, basal cell vacuolization, lamina propria sclerosis, and variable patterns of lymphocytic infiltration. Various unique patterns of stromal sclerosis were described: perivascular, globular, linear, and solid fibrosis/hyalinization; any of them were found to be diagnostic for LS. The variation in the topography and density of lymphocytes was determinant for the identification of LS morphological variants: lichenoid, band-like, lymphocytic depleted, and mixed. A major finding was the identification of the variant designated as lymphocytic depleted LS, which we considered as the morphological prototype of LS associated with penile neoplasia. The detailed description of this complex lesion presented in this study may help pathologists in practice to identify and better define LS. The identification of the special variants suggests a role of the stromal lymphocytes in the process of carcinogenesis. Confirmation of the observations with more studies is necessary to determine the significance of these findings.

Continuous Spatial Sequences of Lichen Sclerosus, Penile Intraepithelial Neoplasia, and Invasive Carcinomas: A Study of 109 Cases

Lichen sclerosus (LSc) with penile cancer is found in about two thirds of specimens. It has been hypothesized that LSc represents a precancerous condition. To qualify as such, in addition to cytological atypia and similarity with the invasive tumor, a spatial correlation between LSc and neoplastic lesions needs to be demonstrated. The purpose of this study was to evaluate such a spatial relationship. Circumcision (28 cases) and penectomy (81 cases) specimens were evaluated. All cases had LSc, penile intraepithelial neoplasia (PeIN), and/or invasive squamous cell carcinomas. We examined LSc in relation to invasive carcinoma, PeIN, and normal epithelia. Invasive squamous cell carcinomas, classified according to the World Health Organization criteria as non–human papillomavirus (HPV)-related and HPV-related PeIN, were present in 100 cases. Non-HPV-related (differentiated) PeIN was the most common subtype associated with LSc (89%). There were 5 spatial patterns identified: (1) LSc adjacent to PeIN (23%), (2) LSc adjacent and comprising PeIN (42%), (3) LSc next to and within invasive carcinomas (8%), (4) LSc throughout the sequence PeIN-invasive carcinoma (24%), and (5) LSc was separate (with normal tissue between the lesions) from PeIN and/or invasive carcinomas in a minority of cases (3%). LSc within the cancer was not previously described. In this series, we found 35 cases with LSc within invasive carcinomas. The striking continuous spatial relationship among LSc, PeIN, and/or invasive carcinoma as shown in this study may be a necessary (but not sufficient) condition for the hypothesis postulating LSc as a penile precancerous lesion.

Toward Minimal Residual Disease-Directed Therapy in Melanoma

Many patients with advanced cancers achieve dramatic responses to a panoply of therapeutics yet retain minimal residual disease (MRD), which ultimately results in relapse. To gain insights into the biology of MRD, we applied single-cell RNA sequencing to malignant cells isolated from BRAF mutant patient-derived xenograft melanoma cohorts exposed to concurrent RAF/MEK-inhibition. We identified distinct drug-tolerant transcriptional states, varying combinations of which co-occurred within MRDs from PDXs and biopsies of patients on treatment. One of these exhibited a neural crest stem cell (NCSC) transcriptional program largely driven by the nuclear receptor RXRG. An RXR antagonist mitigated accumulation of NCSCs in MRD and delayed the development of resistance. These data identify NCSCs as key drivers of resistance and illustrate the therapeutic potential of MRD-directed therapy. They also highlight how gene regulatory network architecture reprogramming may be therapeutically exploited to limit cellular heterogeneity, a key driver of disease progression and therapy resistance.

A phase II study of combined therapy with a BRAF inhibitor (vemurafenib) and interleukin-2 (aldesleukin) in patients with metastatic melanoma

Background: Approximately 50% of melanomas harbor BRAF mutations. Treatment with BRAF +/- MEK inhibition is associated with favorable changes in the tumor microenvironment thus providing the rationale for combining targeted agents with immunotherapy. Methods: Patients with unresectable Stage III or IV BRAF^V600E mutant melanoma were enrolled in a single-center prospective study (n = 6). Patients were eligible to receive two courses of HD-IL-2 and vemurafenib twice daily. The primary endpoint was progression-free survival (PFS) with secondary objectives including overall survival (OS), response rates (RR), and safety of combination therapy as compared to historical controls. Immune profiling was performed in longitudinal tissue samples, when available. Results: Overall RR was 83.3% (95% CI: 36%-99%) and 66.6% at 12 weeks. All patients eventually progressed, with three progressing on treatment and three progressing after the vemurafenib continuation phase ended. Median PFS was 35.8 weeks (95% CI: 16-57 weeks). Median OS was not reached; however, the time at which 75% of patients were still alive was 104.4 weeks. Change in circulating BRAF^V600E levels correlated with response. Though combination therapy was associated with enhanced CD8 T cell infiltrate, an increase in regulatory T cell frequency was seen with HD-IL-2 administration, suggesting a potential limitation in this strategy. Conclusion: Combination vemurafenib and HD-IL-2 is well tolerated and associated with treatment responses. However, the HD-IL-2 induced increase in Tregs may abrogate potential synergy. Given the efficacy of regimens targeting the PD-1 pathway, strategies combining these regimens with BRAF-targeted therapy are currently underway, and the role of combination vemurafenib and HD-IL-2 is uncertain. Trial Registration: Clinical trial information: NCT01754376; https://clinicaltrials.gov/show/NCT01754376.

Ex Vivo Profiling of PD-1 Blockade Using Organotypic Tumor Spheroids

Ex vivo systems that incorporate features of the tumor microenvironment and model the dynamic response to immune checkpoint blockade (ICB) may facilitate efforts in precision immuno-oncology and the development of effective combination therapies. Here, we demonstrate the ability to interrogate ex vivo response to ICB using murine- and patient-derived organotypic tumor spheroids (MDOTS/PDOTS). MDOTS/PDOTS isolated from mouse and human tumors retain autologous lymphoid and myeloid cell populations and respond to ICB in short-term three-dimensional microfluidic culture. Response and resistance to ICB was recapitulated using MDOTS derived from established immunocompetent mouse tumor models. MDOTS profiling demonstrated that TBK1/IKKε inhibition enhanced response to PD-1 blockade, which effectively predicted tumor response in vivo Systematic profiling of secreted cytokines in PDOTS captured key features associated with response and resistance to PD-1 blockade. Thus, MDOTS/PDOTS profiling represents a novel platform to evaluate ICB using established murine models as well as clinically relevant patient specimens.Significance: Resistance to PD-1 blockade remains a challenge for many patients, and biomarkers to guide treatment are lacking. Here, we demonstrate feasibility of ex vivo profiling of PD-1 blockade to interrogate the tumor immune microenvironment, develop therapeutic combinations, and facilitate precision immuno-oncology efforts. Cancer Discov; 8(2); 196-215. ©2017 AACR.See related commentary by Balko and Sosman, p. 143See related article by Deng et al., p. 216This article is highlighted in the In This Issue feature, p. 127.

Lupus and scleroderma overlap features in a 28-year-old man with anti-PL-12 anti-synthetase syndrome

A 28-year-old man with clinically and laboratory diagnosed anti-PL-12 anti-synthetase syndrome (AS) in 2009 developed cutaneous lupus lesions, discoid lupus lesions, and sclerodacytly with finger-tip ulcerations four years following his AS diagnosis. Laboratory tests including +ANA, +anti-dsDNA antibody, +anti-Smith antibody, and +anti-RNP antibody in 2014 confirmed the diagnosis of progression to an overlap syndrome including systemic lupus erythematosus. The patient now also has clinical findings (sclerodacytly, Raynaud phenomenon, finger-tip ulcerations) consistent with scleroderma overlap. In each stage of his evolving connective tissue disease, cutaneous findings have been central to the recognition and monitoring of his overlap syndromes.

Abstract OT3-03-03: Challenges faced across borders to open European academic multicentre projects: The ET-FES program part of the ERA-Net TRANSCAN JTC 2011

Background

The activation of international non-profit clinical trials funded by the European Commission (EC) is challenging given the cross-borders regulations and the need to follow specific timelines according to EC rules. We report here the logistic procedures and challenges faced by 4 academic centres from 4 different countries from the European Union (EU) for the activation of such program in metastatic breast cancer (MBC).

Materials and Methods

The primary objective of the ET-FES program is to validate the use of a new radiotracer 18F Fluoroestradiol (FES), targeting estrogen receptors, as a tool to better predict endocrine responsiveness in MBC, with PET/CT. The trial is sponsored by EO Galliera (Genoa, Italy) and brings together Italy, Spain, France and Germany. In 10/2012, ET-FES was approved for funding from EC under the Seventh Framework Programme after the first ERA-NET TRANSCAN Joint Transnational Call (JTC) for Proposals (2011) on validation of new biomarkers for personalized cancer medicine.

Results

The official start of the program was set up on 06/2013 by the Italian Ministry of Health. Time to institutional review board and to competent authority (CA) approvals were 1.5 and 11, 2 and 5, 3 and 16, and 13 and 14+ months in Italy, France, Spain and Germany respectively. Overall, no blocking comment was raised by the ethical committees; only minor clinical and methodological issues were raised in Germany and Spain. Issues from CA were raised in all countries except France (12, 21 and 23 queries in Italy, Spain and Germany respectively), on quality aspects of 18F-FES investigational medicinal product dossier. At the sponsor level, time to final agreement signature with Advanced Accelerator Applications, the 18F-FES manufacturing company, required 13 months. First patient could be enrolled in Italy 14 and 22 months after ethical committee approval and after the official start of the ET-FES project respectively.

Conclusions

As of May 2016, of 310 patients expected, only 28 have been enrolled from Italy. From a regulatory viewpoint and acknowledging that 18F-FES does not have yet any marketing approval in the EU, the ET-FES program approval process was timely completed at the ethical committee level in Italy, France and Spain. Time to CA approval varied across countries and was timely achieved only in France, due to requirements varying from CA to CA, stressing the serious lack of harmonized procedures although intended by the 2001/20/EC directive. Regarding sponsor's responsibilities (i.e. Italy), the administrative procedures needed to activate this type of EU projects remain critical, appealing for more tolerant time span in order to satisfy all the legal aspects on contracts by public bodies, according to national rules and laws. One needs to be very conscious of these timelines when applying to EU/EC calls, especially when the time allowed for the conduction of research is limited (3 years here), unless jeopardizing the entire multicentre and multinational effort.

Citation Format: Brain E, Corradengo D, Oriana N, Piccardo A, Matteucci F, Cortes J, Harbeck N, Würstlein R, Piris A, Alberini J-L, Merlo DF, Degenhardt T, Turbiez I, Madar O, Monti M, Cesaro A, Rivitti E, Rollandi GA, Iacozzi M, Campazzi E, Campora S, Camporese D, Gennari A. Challenges faced across borders to open European academic multicentre projects: The ET-FES program part of the ERA-Net TRANSCAN JTC 2011 [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT3-03-03.

Lethal melanoma in children: a clinicopathological study of 12 cases

Melanoma in children is rare, representing 3% of paediatric malignancies and <1% of all melanomas. Very few detailed descriptions of bona fide lethal childhood melanomas exist in the literature. We performed a retrospective clinicopathological review of 12 paediatric (≤16 years) melanoma patients who died of metastatic disease, including detailed assessment of architectural and cytomorphological features. There were nine prepubertal patients (median age 7 years old) and three postpubertal cases (median age 15 years old). The patients died on average 45.7 months after diagnosis with the prepubertal subcohort showing a relatively longer time from diagnosis to death. The tumours were bulky (average tumour thickness=10mm), showed brisk mitotic activity (average mitotic count per mm²=7), and were formed by large expansile nodules with sheet-like growth pattern and infiltrative borders in the majority of cases (83%). Cytologically, large grossly pleomorphic epithelioid cells with massive eosinophilic macronucleoli were present in most cases (75%). In this cohort, we did not identify specific features of melanoma that were unique to children. Although melanomas are extremely rarely encountered in childhood, the above-cited unequivocal malignant features should prompt an outright diagnosis of melanoma even in a paediatric patient.

Loss of cohesin complex components STAG2 or STAG3 confers resistance to BRAF inhibition in melanoma

The protein kinase B-Raf proto-oncogene, serine/threonine kinase (BRAF) is an oncogenic driver and therapeutic target in melanoma. Inhibitors of BRAF (BRAFi) have shown high response rates and extended survival in patients with melanoma who bear tumors that express mutations encoding BRAF proteins mutant at Val600, but a vast majority of these patients develop drug resistance. Here we show that loss of stromal antigen 2 (STAG2) or STAG3, which encode subunits of the cohesin complex, in melanoma cells results in resistance to BRAFi. We identified loss-of-function mutations in STAG2, as well as decreased expression of STAG2 or STAG3 proteins in several tumor samples from patients with acquired resistance to BRAFi and in BRAFi-resistant melanoma cell lines. Knockdown of STAG2 or STAG3 expression decreased sensitivity of BRAF(Val600Glu)-mutant melanoma cells and xenograft tumors to BRAFi. Loss of STAG2 inhibited CCCTC-binding-factor-mediated expression of dual specificity phosphatase 6 (DUSP6), leading to reactivation of mitogen-activated protein kinase (MAPK) signaling (via the MAPKs ERK1 and ERK2; hereafter referred to as ERK). Our studies unveil a previously unknown genetic mechanism of BRAFi resistance and provide new insights into the tumor suppressor function of STAG2 and STAG3.

Landscape of Targeted Anti-Cancer Drug Synergies in Melanoma Identifies a Novel BRAF-VEGFR/PDGFR Combination Treatment

A newer generation of anti-cancer drugs targeting underlying somatic genetic driver events have resulted in high single-agent or single-pathway response rates in selected patients, but few patients achieve complete responses and a sizeable fraction of patients relapse within a year. Thus, there is a pressing need for identification of combinations of targeted agents which induce more complete responses and prevent disease progression. We describe the results of a combination screen of an unprecedented scale in mammalian cells performed using a collection of targeted, clinically tractable agents across a large panel of melanoma cell lines. We find that even the most synergistic drug pairs are effective only in a discrete number of cell lines, underlying a strong context dependency for synergy, with strong, widespread synergies often corresponding to non-specific or off-target drug effects such as multidrug resistance protein 1 (MDR1) transporter inhibition. We identified drugs sensitizing cell lines that are BRAF^V600E mutant but intrinsically resistant to BRAF inhibitor PLX4720, including the vascular endothelial growth factor receptor/kinase insert domain receptor (VEGFR/KDR) and platelet derived growth factor receptor (PDGFR) family inhibitor cediranib. The combination of cediranib and PLX4720 induced apoptosis in vitro and tumor regression in animal models. This synergistic interaction is likely due to engagement of multiple receptor tyrosine kinases (RTKs), demonstrating the potential of drug- rather than gene-specific combination discovery approaches. Patients with elevated biopsy KDR expression showed decreased progression free survival in trials of mitogen-activated protein kinase (MAPK) kinase pathway inhibitors. Thus, high-throughput unbiased screening of targeted drug combinations, with appropriate library selection and mechanistic follow-up, can yield clinically-actionable drug combinations.

Loss of BAP1 Expression in Basal Cell Carcinomas in Patients With Germline BAP1 Mutations

OBJECTIVES

Patients with heterozygous germline mutations in BRCA1-associated protein 1 (BAP1), a tumor suppressor gene, develop a tumor predisposition syndrome (OMIM 614327) with increased risk of uveal and cutaneous melanomas, cutaneous atypical and epithelioid melanocytic lesions, lung adenocarcinoma, clear cell renal cell carcinoma, and other tumors. Early recognition of this syndrome is of clinical importance. In addition, screening for BAP1 mutation, loss, and inactivation by performing BAP1 immunohistochemistry on cutaneous lesions would be a simple method for screening patients suspected of having germline BAP1 mutations.

METHODS

We investigated BAP1 expression in seven basal cell carcinomas (BCCs) in two patients with germline BAP1 mutation and a family history of uveal melanoma. Six lesions were from the head and neck region and one from the shoulder. Thirty-one sporadic BCCs were included as controls.

RESULTS

All seven BCCs in the patients with germline BAP1 mutations exhibited loss of BAP1 nuclear staining, while 30 (97%) of 31 sporadic BCCs exhibited positive BAP1 nuclear staining.

CONCLUSIONS

Loss of BAP1 expression could be associated with the development of BCC in patients with germline BAP1 mutations. These results suggest that BCC may be a component of the expanding category of tumors associated with this syndrome.

Abstract PR04: A melanoma transcriptional state distinction influences sensitivity to MAPK pathway inhibitors

The deployment of cancer therapeutics that exploit oncogenic dependencies has yielded remarkable advances in patient treatment. However, the therapeutic benefit of these approaches is transient and the majority of patients develop resistance within several months. BRAFV600E-mutant malignant melanoma provides an illustrative example of this phenomenon: treatment with RAF and MEK inhibitors yields clinical responses in 50-80% of patients. However, 10-20% fail to respond to treatment (intrinsic resistance) and patients that do respond become drug resistant within ∼9 months (acquired resistance), presenting a formidable and unsolved clinical challenge.

It remains incompletely understood why a subset of BRAFV600-mutant melanoma patients (10-20%) fail to respond to MAPK-pathway inhibition. Here, we show that RAF inhibitor sensitive and resistant BRAFV600-mutant melanomas display distinct transcriptional profiles. RAF-inhibitor sensitive cell lines are distinguishable by expression and activity of the melanocytic lineage transcription factor MITF, whereas intrinsically drug-resistant cell lines are defined by expression of the receptor tyrosine kinase AXL and elevated levels of NF-κB signaling. In vitro, these signatures were sufficient to predict MAPK-pathway inhibitor responsiveness in independent panels of melanoma cell lines. MITF-low, AXL/NF-κB high melanomas were resistant to single-agent RAF, MEK and ERK and combined RAF/MEK inhibition. In treatment-naïve patient biopsies, markers of the drug sensitive transcriptional states were associated with improved therapeutic responses to combined RAF/MEK inhibitors in BRAFV600-mutant melanoma. Moreover, in cell lines, NF-κB activation antagonized MITF expression and induced both resistance marker genes and drug resistance.

Thus, distinct cell states characterized by MITF and AXL/NF-κB activity can influence intrinsic resistance to MAPK pathway inhibitors in BRAFV600-mutant melanoma. More broadly, these data suggest that the transcriptional context in which an oncogenic event arises can have a profound impact on the establishment of oncogene-dependencies and associated drug susceptibilities.

Citation Format: Cory Johannessen, David Konieczkowski, Omar Abudayyeh, Jong Wook Kim, Zachary Cooper, Adriano Piris, Dennie Frederick, Michal Barzily-Rokni, Ravid Straussman, Rizwan Haq, David Fisher, Jill Mesirov, William Hahn, Keith Flaherty, Jennifer Wargo, Pablo Tamayo, Levi Garraway. A melanoma transcriptional state distinction influences sensitivity to MAPK pathway inhibitors. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr PR04.

BAP1 and BRAFV600E expression in benign and malignant melanocytic proliferations

BAP1 (BRCA1-associated protein 1) is a tumor suppressor gene whose mutations have recently been reported to increase susceptibility for the development of uveal melanoma, cutaneous atypical and epithelioid melanocytic lesions, clear cell renal cell carcinoma, and other tumors. Screening for BAP1 mutation/loss/inactivation and BRAFV600E mutation can be done by immunohistochemistry. We investigated BAP1 and BRAFV600E expression in 193 sporadic melanocytic lesions (11 dermal nevi, 20 congenital nevi, 40 primary and nondesmoplastic melanomas, 40 desmoplastic melanomas, 23 metastatic melanomas, 17 Spitz nevi, 19 atypical Spitz nevi, 8 atypical Spitz tumors, 14 proliferative nodules arising in congenital nevi, 1 nevus during pregnancy) and 30 melanocytic lesions from 3 patients with family history of uveal melanoma and BAP1 germline mutation. Most sporadic melanocytic lesions exhibited positive BAP1 nuclear staining, except for 1 proliferative nodule arising in congenital nevus, 1 desmoplastic, 1 nevoid, and 2 metastatic melanomas. BRAFV600E positivity was demonstrated in 80% of dermal, 5% of congenital, 6% of Spitz, and 5.5% of atypical Spitz nevi; 29% of proliferative nodules arising in congenital nevi; and 24% of primary and nondesmoplastic and 35% of metastatic melanomas. Combined BAP1 loss and BRAFV600E staining was seen in 67% of BAP1 tumor syndrome-associated lesions and in none of the sporadic melanocytic proliferations including Spitz and atypical Spitz nevi and atypical Spitz tumors, with the exception of 1 primary melanoma. The combined BAP1-BRAFV600E+ immunoprofile appears to be a constant feature of BAP1 tumor syndrome-associated melanocytic lesions, and the designation of Spitz nevi or variants thereof appears to be inaccurate for this group of lesions.

Rhabdomyosarcoma arising in a giant congenital melanocytic nevus

A number of lesions have been documented to arise within congenital melanocytic nevi (CMNs). Although the most frequent malignancy arising within a CMN is melanoma, the association between rhabdomyosarcoma and CMN has rarely been documented. We present a case arising in a 4-month-old girl with a giant CMN. She presented for evaluation of a pedunculated lesion at the superior gluteal crease that had been present since birth and exhibited rapid growth. Biopsy of the lesion revealed two distinct components: an expansile proliferation of pleomorphic cells with varying degrees of cellularity and a proliferation of banal-appearing melanocytic nevic cells. The cells of the expansile proliferation displayed a wide range of morphologic features, including nests of round cells, spindle-shaped cells, and more differentiated rhabdomyoblasts within a myxoid, highly vascularized stroma. Cross-striations, a marker of skeletal muscle differentiation, were present. These tumor cells were strongly immunoreactive with desmin, myo-D1, and myogenin. Fluorescence in situ hybridization analysis with PAX3/7-FKHR probes was negative. A diagnosis of embryonal rhabdomyosarcoma in association with CMN was made. Initial excision revealed tumor at the margins, and the patient underwent reexcision with subsequent chemotherapy with vincristine, actinomycin D, and cyclophosphamide. She was disease-free at the 6-year follow-up. It has been postulated that the combination of melanocytic and rhabdomyoblastic cells within the same lesion may imply derivation from a common pluripotent stem cell or neural crest cell. Clinicians following patients with giant CMN should consider rhabdomyosarcoma in the differential diagnosis of lesions arising within the nevus.

TORC1 suppression predicts responsiveness to RAF and MEK inhibition in BRAF-mutant melanoma

RAF and MEK (mitogen-activated or extracellular signal-regulated protein kinase kinase) inhibitors are effective in treating patients with BRAF-mutant melanoma. However, most responses are partial and short-lived, and many patients fail to respond at all. We found that suppression of TORC1 activity in response to RAF or MEK inhibitors, as measured by decreased phosphorylation of ribosomal protein S6 (P-S6), effectively predicted induction of cell death by the inhibitor in BRAF-mutant melanoma cell lines. In resistant melanomas, TORC1 activity was maintained after treatment with RAF or MEK inhibitors, in some cases despite robust suppression of mitogen-activated protein kinase (MAPK) signaling. In in vivo mouse models, suppression of TORC1 after MAPK inhibition was necessary for induction of apoptosis and tumor response. Finally, in paired biopsies obtained from patients with BRAF-mutant melanoma before treatment and after initiation of RAF inhibitor therapy, P-S6 suppression predicted significantly improved progression-free survival. Such a change in P-S6 could be readily monitored in real time by serial fine-needle aspiration biopsies, making quantitation of P-S6 a valuable biomarker to guide treatment in BRAF-mutant melanoma.

Response to BRAF inhibition in melanoma is enhanced when combined with immune checkpoint blockade

BRAF-targeted therapy results in objective responses in the majority of patients; however, the responses are short lived (∼6 months). In contrast, treatment with immune checkpoint inhibitors results in a lower response rate, but the responses tend to be more durable. BRAF inhibition results in a more favorable tumor microenvironment in patients, with an increase in CD8(+) T-cell infiltrate and a decrease in immunosuppressive cytokines. There is also increased expression of the immunomodulatory molecule PDL1, which may contribute to the resistance. On the basis of these findings, we hypothesized that BRAF-targeted therapy may synergize with the PD1 pathway blockade to enhance antitumor immunity. To test this hypothesis, we developed a BRAF(V600E)/Pten(-/-) syngeneic tumor graft immunocompetent mouse model in which BRAF inhibition leads to a significant increase in the intratumoral CD8(+) T-cell density and cytokine production, similar to the effects of BRAF inhibition in patients. In this model, CD8(+) T cells were found to play a critical role in the therapeutic effect of BRAF inhibition. Administration of anti-PD1 or anti-PDL1 together with a BRAF inhibitor led to an enhanced response, significantly prolonging survival and slowing tumor growth, as well as significantly increasing the number and activity of tumor-infiltrating lymphocytes. These results demonstrate synergy between combined BRAF-targeted therapy and immune checkpoint blockade. Although clinical trials combining these two strategies are ongoing, important questions still remain unanswered. Further studies using this new melanoma mouse model may provide therapeutic insights, including optimal timing and sequence of therapy.

A melanoma cell state distinction influences sensitivity to MAPK pathway inhibitors

Most melanomas harbor oncogenic BRAF(V600) mutations, which constitutively activate the MAPK pathway. Although MAPK pathway inhibitors show clinical benefit in BRAF(V600)-mutant melanoma, it remains incompletely understood why 10% to 20% of patients fail to respond. Here, we show that RAF inhibitor-sensitive and inhibitor-resistant BRAF(V600)-mutant melanomas display distinct transcriptional profiles. Whereas most drug-sensitive cell lines and patient biopsies showed high expression and activity of the melanocytic lineage transcription factor MITF, intrinsically resistant cell lines and biopsies displayed low MITF expression but higher levels of NF-κB signaling and the receptor tyrosine kinase AXL. In vitro, these MITF-low/NF-κB-high melanomas were resistant to inhibition of RAF and MEK, singly or in combination, and ERK. Moreover, in cell lines, NF-κB activation antagonized MITF expression and induced both resistance marker genes and drug resistance. Thus, distinct cell states characterized by MITF or NF-κB activity may influence intrinsic resistance to MAPK pathway inhibitors in BRAF(V600)-mutant melanoma.

SIGNIFICANCE

Although most BRAF(V600)-mutant melanomas are sensitive to RAF and/or MEK inhibitors, a subset fails to respond to such treatment. This study characterizes a transcriptional cell state distinction linked to MITF and NF-κB that may modulate intrinsic sensitivity of melanomas to MAPK pathway inhibitors.

Abstract P5-08-06: PI3K blockade enhances the antitumor activity of eribulin in PIK3CA-mutant eribulin-resistant tumor xenografts

Eribulin is a recently approved microtubule-targeting agent (MTA) for the management of heavily pretreated metastatic breast cancer (BC) patients. Constitutive PI3K/Akt/mTOR survival pathway activation, either via mutational activation of the PI3K catalytic subunit (PIK3CA) or via inactivation of the tumor suppressor PTEN, may confer resistance to MTAs. Hence, we hypothesized that PI3K-pathway activation limits the antitumor activity of eribulin in HER2-negative BC and that PI3K inhibition enhances the efficacy of this chemotherapeutic agent.

The predictive value of PIK3CA mutation or PTEN loss towards eribulin response was interrogated in vitro, using a panel of fourteen HER2-negative BC cell lines, and in vivo using six tumor models from cell-line or patient-derived tumors. While PIK3CA mutation did not seem to be predictive in vitro, the PIK3CA-mutated xenograft models underwent tumor progression upon single-agent eribulin therapy (Table 1). In the absence of concomitant PIK3CA mutation, PTEN loss was neither predictive in vitro nor in vivo. Moreover, eribulin induced PI3K-pathway activation in tumor xenografts, a potential escape mechanism to MTA-therapy. To validate the negative predictive value of PIK3CA mutation, BC tumors from patients treated with eribulin in the neoadjuvant and in the metastatic setting are being queried, as the pharmacodynamic activation of the PI3K-pathway upon eribulin treatment.

Class I pan-PI3K (BKM120) or PI3K-a-specific (BYL719) inhibitors were used in vitro to block the PI3K-pathway concomitantly with eribulin treatment, resulting in enhanced antiproliferative and proapoptotic activity. Strikingly, in PIK3CA mutant xenograft models, while eribulin alone exhibited limited antitumor activity compared to PIK3CA-wild type models, co-administration of a PI3K inhibitor induced marked tumor regression (BKM120 data in Table 1, BYL719 data will be reported). Moreover, addition of the PI3K inhibitor at progression with eribulin single-agent also resulted in tumor regression. Of note, PIK3CA-wild type models also exhibited increased antitumor activity with the combined therapy compared to single-agent treatments. The precise mechanism by which the combination of eribulin and a PI3K-targeting agent results in tumor regression is currently under investigation, embracing both the induction of mitotic catastrophe in tumor cells and the regularization of the tumor vasculature.

These results support the clinical development of therapeutic regimens combining PI3K-inhibitors to the approved MTA eribulin and might be predictive of clinical benefit both in the PIK3CA-mutant and -wild type breast cancer population.

Table 1. Percentage change in tumor volume.StatusPIK3CA mutantPIK3CA mutant and PTEN-lowPTEN-lowWTModel/ TreatmentMCF7LPDX44CAL51MDA-MB-468PDX88PDX98Eribulin39 ± 9683 ± 51364 ± 127-47 ± 14-26 ± 34-36 ± 33BKM120501 ± 169116 ± 111119 ± 73-9 ± 23128 ± 3787 ± 112Eribulin + BKM120-70 ± 27-80 ± 1051 ± 46-75 ± 12-94 ± 5-65 ± 13Patient- (PDX) and cell line-derived tumor xenografts were treated with eribulin mesylate (0.1mg/kg, 3IW) and/or BKM120 (27.5 mg/kg, 6IW) for 26-31 days.. IW, in week.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-08-06.

Cutaneous and mammary apocrine carcinomas have different immunoprofiles

Often the distinction of cutaneous apocrine carcinoma from metastatic mammary apocrine carcinoma to the skin can be a diagnostic dilemma because both tumors share similar histologic features and have overlapping immunohistochemical profile. We compared the expression of adipophilin, cytokeratin 5/6, p63, GATA3, mammaglobin, androgen receptor, estrogen receptor, progesterone receptor, and HER2 by immunohistochemistry in 14 cutaneous apocrine carcinomas (11 primary tumors, 3 metastases) and 26 primary apocrine carcinomas of the breast. Whereas focal adipophilin staining was seen in 36% (5/14) of cutaneous apocrine carcinoma, strong and diffuse adipophilin staining was seen in 88% (22/25) of mammary apocrine carcinoma (P = .0013). Differences in estrogen receptor and progesterone receptor expression were also statistically significant (P = .018 and .043). Androgen receptor was strongly positive in all cutaneous and mammary cases. Although there was no significant difference in the frequency of expression of cytokeratin 5/6, p63, HER2, GATA3, and mammaglobin in cutaneous apocrine carcinoma versus mammary apocrine carcinoma, strong and diffuse cytokeratin 5/6 and/or mammaglobin expression were seen only in cutaneous apocrine carcinoma. In conclusion, cutaneous apocrine carcinoma is likely adipophilin- ER+ PR+/- HER2- and can exhibit strong and diffuse cytokeratin 5/6 and/or mammaglobin expression. On the contrary, a mammary apocrine carcinoma is likely adipophilin+ ER- PR- and often exhibit 3+ HER2 with corresponding HER2 gene amplification. A panel of adipophilin, ER, PR, HER2, cytokeratin 5/6, and mammaglobin may be helpful in distinguishing cutaneous apocrine carcinoma from mammary apocrine carcinoma.

Sporadic naturally occurring melanoma in dogs as a preclinical model for human melanoma

Melanoma represents a significant malignancy in humans and dogs. Different from genetically engineered models, sporadic canine melanocytic neoplasms share several characteristics with human disease that could make dogs a more relevant preclinical model. Canine melanomas rarely arise in sun-exposed sites. Most occur in the oral cavity, with a subset having intra-epithelial malignant melanocytes mimicking the in situ component of human mucosal melanoma. The spectrum of canine melanocytic neoplasia includes benign lesions with some analogy to nevi, as well as invasive primary melanoma, and widespread metastasis. Growing evidence of distinct subtypes in humans, differing in somatic and predisposing germ-line genetic alterations, cell of origin, epidemiology, relationship to ultraviolet radiation and progression from benign to malignant tumors, may also exist in dogs. Canine and human mucosal melanomas appear to harbor BRAF, NRAS, and c-kit mutations uncommonly, compared with human cutaneous melanomas, although both species share AKT and MAPK signaling activation. We conclude that there is significant overlap in the clinical and histopathological features of canine and human mucosal melanomas. This represents opportunity to explore canine oral cavity melanoma as a preclinical model.

Abstract C137: Rapid assessment of TORC1 suppression as a functional biomarker predicting responsiveness to RAF and MEK inhibitors in BRAF-mutant melanoma patients

The clinical development of selective RAF and MEK inhibitors has transformed the treatment of the ∼50% of melanoma patients whose tumors harbor BRAF mutations. However, a substantial percentage of these patients fail to respond to therapy, and most responses are partial and short-lived. Although multiple mechanisms of resistance have been identified in BRAF-mutant melanoma, no clinically useful biomarkers have been established to predict which patients are most likely to demonstrate sensitivity or resistance to RAF or MEK inhibitors. We found that suppression of TORC1 activity in response to RAF or MEK inhibitors, as measured by decreased phosphorylation of ribosomal protein-S6 (P-S6), was a functional biomarker that effectively predicted sensitivity in BRAF-mutant melanoma cell lines in vitro and in mouse tumor xenografts. In sensitive melanomas, TORC1 and P-S6 were suppressed in response to RAF or MEK inhibitors, but in resistant melanomas, TORC1 activity was maintained, in some cases despite robust suppression of MAPK signaling by these inhibitors. In mouse models, suppression of TORC1 after MAPK inhibition was necessary for induction of apoptosis and tumor response in vivo. Notably, in paired biopsies obtained from patients with BRAF-mutant melanoma before treatment and after initiation of RAF inhibitor therapy, P-S6 suppression was associated with significantly improved progression-free survival [HR 0.19, 95% CI 0.01-0.84, p=0.03]. Finally, we found that changes in P-S6 in patients’ tumor cells could be readily monitored in real-time by multiplexed, quantitative immunofluorescence microscopy of serial fine-needle aspiration biopsies obtained from patients before and during the first 2 weeks of RAF inhibitor therapy. This approach provides a minimally-invasive means of rapidly monitoring the efficacy of treatment, before changes in tumor volume are apparent by traditional radiographic imaging. Together, these results establish suppression of P-S6 after initiation of RAF inhibitor therapy as a robust potential functional biomarker to guide the treatment of patients with BRAF-mutant melanoma, and present a powerful methodology for monitoring changes in potentially any signaling pathway in response to targeted therapies in patients.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):C137.

Citation Format: Ryan B. Corcoran, S. Michael Rothenberg, Aaron N. Hata, Anthony C. Faber, Adriano Piris, Rosalynn M. Nazarian, Ronald D. Brown, Jason T. Godfrey, Daniel Winokur, John Walsh, Mari Mino-Kenudson, Shyamala Maheswaran, Jeffrey Settleman, Jennifer A. Wargo, Keith T. Flaherty, Daniel A. Haber, Jeffrey A. Engelman. Rapid assessment of TORC1 suppression as a functional biomarker predicting responsiveness to RAF and MEK inhibitors in BRAF-mutant melanoma patients. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr C137.

BRAF inhibition is associated with increased clonality in tumor-infiltrating lymphocytes

There have been significant advances with regard to BRAF-targeted therapies against metastatic melanoma. However, the majority of patients receiving BRAF inhibitors (BRAFi) manifest disease progression within a year. We have recently shown that melanoma patients treated with BRAFi exhibit an increase in melanoma-associated antigens and in CD8+ tumor-infiltrating lymphocytes in response to therapy. To characterize such a T-cell infiltrate, we analyzed the complementarity-determining region 3 (CDR3) of rearranged T-cell receptor (TCR) β chain-coding genes in tumor biopsies obtained before the initiation of BRAFi and 10-14 d later. We observed an increase in the clonality of tumor-infiltrating lymphocytes in 7 of 8 patients receiving BRAFi, with a statistically significant 21% aggregate increase in clonality. Over 80% of individual T-cell clones detected after initiation of BRAFi treatment were new clones. Interestingly, the comparison of tumor infiltrates with clinical responses revealed that patients who had a high proportion of pre-existing dominant clones after the administration of BRAFi responded better to therapy than patients who had a low proportion of such pre-existing dominant clones following BRAFi. These data suggest that although the inhibition of BRAF in melanoma patients results in tumor infiltration by new lymphocytes, the response to treatment appears to be related to the presence of a pre-existing population of tumor-infiltrating T-cell clones.

Abstract 4568: Rapid assessment of TORC1 suppression predicts responsiveness to RAF and MEK inhibition in BRAF mutant melanoma

The clinical development and potent efficacy of selective RAF and MEK inhibitors has transformed the treatment of the ∼50% of melanoma patients whose tumors harbor BRAF mutations. However, a substantial percentage of these patients fail to respond to therapy, and all who respond eventually develop resistance. We found that suppression of TORC1 activity, as measured by decreases in ribosomal protein S6 phosphorylation (P-S6) in response to RAF or MEK inhibitors, was a highly effective predictor of sensitivity in BRAF mutant melanoma cell lines in vitro and in mouse xenografts. TORC1 and P-S6 were suppressed in response to RAF or MEK inhibitors in sensitive but not resistant melanoma cells, despite robust suppression of the MAPK pathway by these inhibitors. Notably, suppression of P-S6 levels, as assessed by immunohistochemistry in paired biopsies obtained from BRAF mutant melanoma patients before and during treatment, was associated with significantly improved progression-free survival. Finally, we show that changes in P-S6 levels specifically in tumor cells can be readily monitored by multiplexed, quantitative immunofluorescence microscopy of fine needle aspiration biopsies obtained from patients before and during the first two weeks of BRAF inhibitor therapy. This provides a minimally invasive means for monitoring the efficacy of treatment in real time, before changes in tumor volume are apparent on traditional radiographs. Together, these results establish changes in P-S6 levels with therapy as a robust biomarker to guide the treatment of patients with BRAF mutant melanoma, and present a powerful methodology for monitoring changes in potentially any signaling pathway in response to therapy in patients.

Citation Format: Ryan B. Corcoran, Stephen M. Rothenberg, Aaron N. Hata, Anthony C. Faber, Daniel Winokur, Adriano Piris, Rosalynn M. Nazarian, Ronald D. Brown, Jason T. Godfrey, Mari Mino-Kenudson, Jeffrey Settleman, Jennifer A. Wargo, Keith T. Flaherty, Daniel A. Haber, Jeffrey A. Engelman. Rapid assessment of TORC1 suppression predicts responsiveness to RAF and MEK inhibition in BRAF mutant 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 4568. doi:10.1158/1538-7445.AM2013-4568

Abstract 2338: BRAF inhibition is associated with increased clonality of tumor infiltrating lymphocytes

There have been significant advances in the past few years with regard to BRAF-targeted therapy for metastatic melanoma, however the majority of patients have disease progression within 6 to 7 months. We have previously shown that BRAF inhibition in melanoma in vitro is associated with an increase in melanoma antigens and increased reactivity to antigen specific T cells. More recently, we corroborated these findings in vivo in patients with melanoma undergoing treatment with BRAF inhibitors, demonstrating an increase in melanoma antigens and a significant increase in CD8+ T cells following treatment. However, the nature of this immune response to BRAF inhibition is poorly understood. The goal of the present studies is to better define the T cell infiltrate, so that we can develop a therapeutic strategy to leverage their presence.

To do this, we performed tumor biopsies in patients with metastatic melanoma undergoing treatment with BRAF inhibitors at two time-points: pre-treatment (day 0), and on-treatment (day 10-14). Biopsies were also taken at time of progression when applicable. DNA was isolated and the CDR3 regions of rearranged TCR beta chain genes within the tumor were sequenced and analyzed using the immunoSEQ platform by Adaptive Biotechnologies. Results demonstrated a significant increase in the clonality in the tumor infiltrating lymphocytes in 7 of the 8 patients in on-treatment vs. pre-treatment samples, suggesting that treatment with a BRAF inhibitor may induce an antigen-specific T cell response. We also sought to determine if the increase in T cells associated with BRAF inhibition is related to an infiltration of new T cell clones or a proliferation of existing clones within the tumor. To study this, we analyzed the total T cell clones in these patient samples with regard to their presence or absence in the pre-treatment compared to on-treatment samples. Results demonstrate that over 80% of the individual clones detected after initiation of BRAF-targeted therapy are new clones, suggesting that this therapy is associated with an influx of TIL into the tumors. However, if attention is focused only on the most prevalent clones rather than the total clones, there is a dichotomous relationship between change in clonal populations and magnitude of tumor regression. Namely, those who have persistence of the same dominant clones had a good treatment response, whereas those who had a change in the dominant clonal populations had a poor response. Taken together, this data suggest that though BRAF inhibition in melanoma results in infiltration of new TIL, response to treatment is dependent on a pre-existing population of TIL clones. This data has important clinical implications, and may ultimately help predict who is likely to derive the greatest benefit from BRAF-targeted therapy. A better understanding of this response may also guide us in developing rational combination therapy in the treatment of melanoma.

Citation Format: Zachary A. Cooper, Dennie T. Frederick, Ryan J. Sullivan, Donald P. Lawrence, Adriano Piris, Keith T. Flaherty, David A. Fisher, Jennifer A. Wargo. BRAF inhibition is associated with increased clonality of tumor infiltrating lymphocytes. [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 2338. doi:10.1158/1538-7445.AM2013-2338

Wolf Isotopic Response Manifesting as Postherpetic Granuloma Annulare: A Case Series

Context.— Wolf isotopic response has infrequently been reported in the literature, mainly as isolated case reports.

Objective.— To aid in recognition of the occurrence of postherpetic granuloma annulare for accurate histologic interpretation of granulomatous dermatitides.

Design.— We report 5 cases of patients with Wolf isotopic response manifesting as granuloma annulare, developing in a site of previous herpes zoster, and discuss the clinicopathologic findings.

Results.— Previous infection with herpes zoster or herpes simplex virus was found in 5 of 5 cases reported. The differential diagnosis of a dermal lymphohistiocytic infiltrate with multinucleated giant cells includes postherpetic granuloma annulare.

Conclusions.— All cases of postherpetic Wolf isotopic response reported in this series revealed granuloma annulare, with a perineurovascular or perifollicular pattern of lymphohistiocytic infiltration including multinucleated giant cells, and occurred following herpes zoster or herpes simplex infection, although herpes viral infection was not always associated with a subsequent isotopic eruption. Awareness of this entity can aid in the clinicopathologic diagnosis of granuloma annulare occurring at the site of prior herpes viral infection.

BRAF inhibition is associated with enhanced melanoma antigen expression and a more favorable tumor microenvironment in patients with metastatic melanoma

PURPOSE

To evaluate the effects of BRAF inhibition on the tumor microenvironment in patients with metastatic melanoma.

EXPERIMENTAL DESIGN

Thirty-five biopsies were collected from 16 patients with metastatic melanoma pretreatment (day 0) and at 10 to 14 days after initiation of treatment with either BRAF inhibitor alone (vemurafenib) or BRAF + MEK inhibition (dabrafenib + trametinib) and were also taken at time of progression. Biopsies were analyzed for melanoma antigens, T-cell markers, and immunomodulatory cytokines.

RESULTS

Treatment with either BRAF inhibitor alone or BRAF + MEK inhibitor was associated with an increased expression of melanoma antigens and an increase in CD8+ T-cell infiltrate. This was also associated with a decrease in immunosuppressive cytokines [interleukin (IL)-6 and IL-8] and an increase in markers of T-cell cytotoxicity. Interestingly, expression of exhaustion markers TIM-3 and PD1 and the immunosuppressive ligand PDL1 was increased on treatment. A decrease in melanoma antigen expression and CD8 T-cell infiltrate was noted at time of progression on BRAF inhibitor alone and was reversed with combined BRAF and MEK inhibition.

CONCLUSIONS

Together, these data suggest that treatment with BRAF inhibition enhances melanoma antigen expression and facilitates T-cell cytotoxicity and a more favorable tumor microenvironment, providing support for potential synergy of BRAF-targeted therapy and immunotherapy. Interestingly, markers of T-cell exhaustion and the immunosuppressive ligand PDL1 are also increased with BRAF inhibition, further implying that immune checkpoint blockade may be critical in augmenting responses to BRAF-targeted therapy in patients with melanoma.

Sentinel lymph node metastasis is not predictive of poor outcome in patients with problematic spitzoid melanocytic tumors

The diagnosis and clinical management of spitzoid melanocytic tumors with atypical features remain problematic and controversial. In the past decade, sentinel lymph node mapping has been advocated as a diagnostic test in this setting to discriminate melanoma from benign tumors. Recent studies, however, consistently show that despite the presence of lymph node metastases these patients almost always fare well. We investigated the outcome of patients with atypical Spitz tumors and spitzoid melanoma who received sentinel lymph node mapping to clarify current recommendations in managing patients with these diagnostically challenging tumors. A search of the electronic files of the Massachusetts General Hospital Pathology Service identified 41 patients treated with sentinel lymph node biopsy for atypical Spitz tumor or spitzoid melanoma from 1998 to 2008. These patients included 23 patients with atypical Spitz tumors and 17 patients with spitzoid melanoma. Sentinel lymph nodes were positive in 26% of patients with atypical Spitz tumors (6/23) and 35% with spitzoid melanomas (6/17). One patient with spitzoid melanoma developed in-transit metastasis; 0 of 40 patients developed metastases beyond the regional lymph node basin with a mean follow-up of 57 months. Sentinel lymph node biopsy may not be a reliable prognostic discriminatory test in patients with atypical Spitz tumors. Patients with spitzoid melanomas and positive sentinel lymph nodes have a more indolent course than those with bona fide conventional melanoma and positive sentinel nodes.

Abstract PR8: Insensitivity to RAF inhibition by vemurafenib in BRAF mutant colorectal cancer by EGFR-mediated reactivation of MAPK signaling

BRAF mutations occur in 10–15% of colorectal cancers (CRCs) and confer adverse outcome in the metastatic setting. While RAF inhibitors such as vemurafenib (PLX4032) have proven effective in BRAF mutant melanoma (∼60–80% response rates), they are surprisingly ineffective in BRAF mutant CRCs (∼5% response rate), and the reason for this disparity remains unclear. Compared to BRAF mutant melanoma cells, BRAF mutant CRC cells were less sensitive to vemurafenib, and P-ERK suppression was not sustained in response to treatment. Although transient inhibition of phospho-ERK by vemurafenib was observed in CRC, rapid ERK re-activation occurred through EGFR-mediated activation of RAS and CRAF. BRAF mutant CRC cell lines and patient tumor specimens expressed significantly higher levels of phospho-EGFR than BRAF mutant melanoma cell lines and primary tumor specimens, suggesting that CRCs are specifically poised for EGFR-mediated resistance. Combined RAF and EGFR inhibition blocked reactivation of MAPK signaling in BRAF mutant CRC cells and markedly improved efficacy in vitro. In vivo, combined RAF and EGFR inhibition led to sustained suppression of MAPK signaling and to robust tumor regressions in BRAF mutant colorectal xenografts. These findings support evaluation of combined RAF and EGFR inhibition in clinical trials in patients with BRAF mutant CRC.

This proffered talk is also presented as Poster B11.

Germline BAP1 inactivation is preferentially associated with metastatic ocular melanoma and cutaneous-ocular melanoma families

Background

BAP1 has been shown to be a target of both somatic alteration in high-risk ocular melanomas (OM) and germline inactivation in a few individuals from cancer-prone families. These findings suggest that constitutional BAP1 changes may predispose individuals to metastatic OM and that familial permeation of deleterious alleles could delineate a new cancer syndrome.

Design

To characterize BAP1's contribution to melanoma risk, we sequenced BAP1 in a set of 100 patients with OM, including 50 metastatic OM cases and 50 matched non-metastatic OM controls, and 200 individuals with cutaneous melanoma (CM) including 7 CM patients from CM-OM families and 193 CM patients from CM-non-OM kindreds.

Results

Germline BAP1 mutations were detected in 4/50 patients with metastatic OM and 0/50 cases of non-metastatic OM (8% vs. 0%, p = 0.059). Since 2/4 of the BAP1 carriers reported a family history of CM, we analyzed 200 additional hereditary CM patients and found mutations in 2/7 CM probands from CM-OM families and 1/193 probands from CM-non-OM kindreds (29% vs. 0.52%, p = .003). Germline mutations co-segregated with both CM and OM phenotypes and were associated with the presence of unique nevoid melanomas and highly atypical nevoid melanoma-like melanocytic proliferations (NEMMPs). Interestingly, 7/14 germline variants identified to date reside in C-terminus suggesting that the BRCA1 binding domain is important in cancer predisposition.

Conclusion

Germline BAP1 mutations are associated with a more aggressive OM phenotype and a recurrent phenotypic complex of cutaneous/ocular melanoma, atypical melanocytic proliferations and other internal neoplasms (ie. COMMON syndrome), which could be a useful clinical marker for constitutive BAP1 inactivation.

Abstract LB-350: EGFR-mediated re-activation of MAPK signaling contributes to insensitivity of BRAF mutant colorectal cancers to RAF inhibition by vemurafenib

Oncogenic BRAF mutations occur in 10-15% of colorectal cancers (CRCs) and confer adverse outcome. While RAF inhibitors such as vemurafenib (PLX4032) have produced dramatic response rates in BRAF mutant melanoma (∼60-80%), they are surprisingly ineffective in BRAF mutant CRCs (∼5% response rate), and the reason for this disparity remains unclear. Compared to BRAF mutant melanoma cells, BRAF mutant CRC cells were less sensitive to vemurafenib, and P-ERK suppression was not sustained in response to treatment. Although transient inhibition of phospho-ERK by vemurafenib was observed in CRC, rapid ERK re-activation occurred through EGFR-mediated activation of RAS and CRAF. BRAF mutant CRC cell lines and patient tumor specimens expressed higher levels of phospho-EGFR than BRAF mutant melanoma cell lines and primary tumor specimens, suggesting that CRCs are specifically poised for EGFR-mediated resistance. Combined RAF and EGFR inhibition blocked reactivation of MAPK signaling in BRAF mutant CRC cells, markedly improved efficacy in vitro, and led to robust tumor regressions in vivo in BRAF mutant xenografts models. These findings support combined RAF and EGFR inhibition as a novel and promising therapeutic strategy for evaluation in clinical trials in patients with BRAF mutant CRC.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-350. doi:1538-7445.AM2012-LB-350

EGFR-mediated re-activation of MAPK signaling contributes to insensitivity of BRAF mutant colorectal cancers to RAF inhibition with vemurafenib

BRAF mutations occur in 10-15% of colorectal cancers (CRCs) and confer adverse outcome. While RAF inhibitors such as vemurafenib (PLX4032) have proven effective in BRAF mutant melanoma, they are surprisingly ineffective in BRAF mutant CRCs, and the reason for this disparity remains unclear. Compared to BRAF mutant melanoma cells, BRAF mutant CRC cells were less sensitive to vemurafenib, and P-ERK suppression was not sustained in response to treatment. Although transient inhibition of phospho-ERK by vemurafenib was observed in CRC, rapid ERK re-activation occurred through EGFR-mediated activation of RAS and CRAF. BRAF mutant CRCs expressed higher levels of phospho-EGFR than BRAF mutant melanomas, suggesting that CRCs are specifically poised for EGFR-mediated resistance. Combined RAF and EGFR inhibition blocked reactivation of MAPK signaling in BRAF mutant CRC cells and markedly improved efficacy in vitro and in vivo. These findings support evaluation of combined RAF and EGFR inhibition in BRAF mutant CRC patients.

SIGNIFICANCE

BRAF valine 600 (V600) mutations occur in 10% to 15% of colorectal cancers, yet these tumors show a surprisingly low clinical response rate (~5%) to selective RAF inhibitors such as vemurafenib, which have produced dramatic response rates (60%–80%) in melanomas harboring the identical BRAF V600 mutation. We found that EGFR-mediated MAPK pathway reactivation leads to resistance to vemurafenib in BRAF-mutant colorectal cancers and that combined RAF and EGFR inhibition can lead to sustained MAPK pathway suppression and improved efficacy in vitro and in tumor xenografts.

Increased diagnosis of thin superficial spreading melanomas: A 20-year study

BACKGROUND

Diagnostic practice by dermatopathologists evaluating pigmented lesions may have evolved over time.

OBJECTIVES

We sought to investigate diagnostic drift among a group of dermatopathologists asked to re-evaluate cases initially diagnosed 20 years ago.

METHODS

Twenty nine cases of dysplastic nevi with severe atypia and 11 cases of thin radial growth-phase melanoma from 1988 through 1990 were retrieved from the pathology files of the Massachusetts General Hospital. All dermatopathologists who had rendered an original diagnosis for any of the 40 slides and the current faculty in the Massachusetts General Hospital Dermatopathology Unit were invited to evaluate the slide set in 2008 through 2009.

RESULTS

The mean number of melanoma diagnoses by the 9 study participants was 18, an increase from the original 11 melanoma diagnoses. A majority agreed with the original diagnosis of melanoma in all 11 cases. In contrast, a majority of current raters diagnosed melanoma in 4 of the 29 cases originally reported as dysplastic nevus with severe atypia. Interrater agreement over time was excellent (kappa 0.88) and fair (kappa 0.47) for cases originally diagnosed as melanoma and severely atypical dysplastic nevus, respectively.

LIMITATIONS

The unbalanced composition of the slide set, lack of access to clinical or demographic information, access to only one diagnostic slide, and imposed dichotomous categorization of tumors were limitations.

CONCLUSIONS

A selected cohort of dermatopathologists demonstrated a general trend toward the reclassification of prior nonmalignant diagnoses of severely atypical dysplastic nevi as malignant but did not tend to revise prior diagnoses of cutaneous melanoma as benign.