Genomic modelling of the ESR1 Y537S mutation for evaluating function and new therapeutic approaches for metastatic breast cancer

Drugs that inhibit estrogen receptor-α (ER) activity have been highly successful in treating and reducing breast cancer progression in ER-positive disease. However, resistance to these therapies presents a major clinical problem. Recent genetic studies have shown that mutations in the ER gene are found in >20% of tumours that progress on endocrine therapies. Remarkably, the great majority of these mutations localize to just a few amino acids within or near the critical helix 12 region of the ER hormone binding domain, where they are likely to be single allele mutations. Understanding how these mutations impact on ER function is a prerequisite for identifying methods to treat breast cancer patients featuring such mutations. Towards this end, we used CRISPR-Cas9 genome editing to make a single allele knock-in of the most commonly mutated amino acid residue, tyrosine 537, in the estrogen-responsive MCF7 breast cancer cell line. Genomic analyses using RNA-seq and ER ChIP-seq demonstrated that the Y537S mutation promotes constitutive ER activity globally, resulting in estrogen-independent growth. MCF7-Y537S cells were resistant to the anti-estrogen tamoxifen and fulvestrant. Further, we show that the basal transcription factor TFIIH is constitutively recruited by ER-Y537S, resulting in ligand-independent phosphorylation of Serine 118 (Ser118) by the TFIIH kinase, cyclin-dependent kinase (CDK)7. The CDK7 inhibitor, THZ1 prevented Ser118 phosphorylation and inhibited growth of MCF7-Y537S cells. These studies confirm the functional importance of ER mutations in endocrine resistance, demonstrate the utility of knock-in mutational models for investigating alternative therapeutic approaches and highlight CDK7 inhibition as a potential therapy for endocrine-resistant breast cancer mediated by ER mutations.

Extracellular vesicles swarm the cancer microenvironment: from tumor-stroma communication to drug intervention

Intercellular communication sets the pace for transformed cells to survive and to thrive. Extracellular vesicles (EVs), such as exosomes, microvesicles and large oncosomes, are involved in this process shuttling reciprocal signals and other molecules between transformed and stromal cells, including fibroblasts, endothelial and immune cells. As a result, these cells are adapted or recruited to a constantly evolving cancer microenvironment. Moreover, EVs take part in the response to anticancer therapeutics not least by promoting drug resistance throughout the targeted tumor. Finally, circulating EVs can also transport important molecules to remote destinations in order to prime metastatic niches in an otherwise healthy tissue. Although the understanding of EV biology remains a major challenge in the field, their characteristics create new opportunities for advances in cancer diagnostics and therapeutics.

Abstract P4-03-02: Stromal kinome screening identifies a novel regulatory kinase implicated in fibroblast-mediated progression of invasion in triple negative breast cancer tumours

This abstract was not presented at the symposium.

Initiation of adjuvant chemotherapy within 8 weeks of elective colorectal resection improves overall survival regardless of reoperation

AIM

Reoperation after elective colorectal resection may delay the start of adjuvant chemotherapy (AC). The study investigated the dual impact of a reoperation and AC delay on overall survival (OS).

METHOD

The Hospital Episode Statistics database was analysed between 1997 and 2012. Patients were divided into colon and rectal cancer cohorts and data were analysed based on whether there was delay in receiving AC beyond 8 weeks and whether a patient suffered reoperation within 30 days. Multivariate regression analysis was undertaken to investigate the relationship between delay in giving AC and reoperation and their combined effect on OS.

RESULTS

Logistic regression showed reoperation, amongst other things, to be an independent predictor of AC delay, in both colon and rectal cancer (colon, odds ratio 2.31, P < 0.001; rectal, odds ratio 2.19, P < 0.001). There was no significant difference in OS between patients who had no AC delay but suffered a reoperation and patients who had no AC delay and no reoperation. Patients who had AC delay but no reoperation, however, had significantly worse OS compared to those who had no AC delay and no reoperation [colon, hazard ratio (HR) 1.16, P < 0.001; rectal, HR 1.17, P < 0.001]. Individuals who had both AC delay and a reoperation also had worse OS compared with patients who had neither (colon, HR 1.33, P = 0.037; rectal, HR 1.38, P < 0.001).

CONCLUSION

Delayed receipt of AC beyond 8 weeks after surgery is associated with significantly reduced OS regardless of reoperation status in both colon and rectal cancer patients.

Epirubicin dose and sequential hormonal therapy-Mature results of the HMFEC randomised phase III trial in premenopausal patients with node positive early breast cancer

BACKGROUND

The hormonal manipulation 5-Fluoro-uracil Epirubicin Cyclophosphamide (HMFEC) trial was developed at a time of uncertainty around the dose intensity of chemotherapy given to premenopausal patients with node positive breast cancer and to the benefits of tailored endocrine therapy in such patients.

PATIENTS AND METHODS

HMFEC was a multi-centre, phase III, open label, randomised controlled trial with a 2 × 2 factorial design. Eligible patients were premenopausal with node positive early breast cancer; significant cardiac disease or uncontrolled hypertension was exclusion criterion. Patients were allocated to receive either eight cycles of FE50C or FE75C (given 3 weekly) with or without hormone manipulation (HM; tamoxifen or luteinising hormone releasing hormone (LHRH) agonists according to residual hormone levels at the end of chemotherapy) irrespective of ER status. The primary end-point was disease free survival (DFS). Principal analyses were by intention to treat (ITT); however, to reflect contemporary practice, subgroup analyses according to ER status were also conducted. The mature follow-up now available from this modest sized trial enables presentation of definitive results.

RESULTS

Between 1992 and 2000 a total of 785 patients were randomised into the HMFEC trial (203 FE50C-HM, 191 FE50C+HM, 198 FE75C-HM, 193 FE75C+HM). At a median follow-up of 7.4 years, 245 DFS events have been reported (92 ER-, 153 ER+/unknown). The effects on DFS were not statistically significantly different according to epirubicin dose (hazard ratio [HR] = 0.82, 95% confidence interval [CI] 0.63-1.06; p = 0.13 FE75C versus FE50C); however, FE75C appeared to induce more alopecia and neutropenia. No statistically significant evidence was observed to support an improvement in DFS in patients allocated HM either overall (HR = 0.88, 95% CI 0.68-1.13; p = 0.32) or in patients with ER+/unknown disease (HR = 0.85, 95% CI 0.62-1.17; p = 0.32) although effect sizes are consistent with worthwhile clinical effects. Overall, there was no evidence of a difference in survival between any of the four treatment groups of the trial.

CONCLUSION

Higher doses of epirubicin cause more adverse events in the absence of clear improvement in overall survival. Endocrine therapy with either tamoxifen or goserelin provided no significant added benefit to cytotoxic chemotherapy in this group of patients.

TRIAL REGISTRATION NUMBER

ISRCTN98335268.

Targeting tumor-stroma crosstalk: the example of the NT157 inhibitor

Recent clinical research has provided evidence that cancer progression and therapy resistance is driven not only by tumor's genetic profile but also by complex paracrine interactions within the tumor microenvironment (TME). The role of TME in modulating tumor drug sensitivity is increasingly recognized and targeting TME has been the focus of novel therapeutic approaches. Two recent reports show that a new anti-cancer drug, the inhibitor NT157 has the potential to inhibit IGF-1R and STAT3 signaling pathways in cancer cells and stroma cells of TME leading to a decrease in cancer cell survival.

TAMing resistance to multi-targeted kinase inhibitors through Axl and Met inhibition

TAM (Tyro3-Axl-Mer) receptor tyrosine kinases and Met are implicated in several hallmarks of cancer progression including sustained angiogenesis, enhanced motility, tissue invasion and acquisition of metastatic potential through the upregulation of epithelial-to-mesenchymal transition. Increasing evidence has confirmed Axl and Met as emerging central drivers of adaptive resistance to targeted therapies across a wide variety of cancers. In this issue of Oncogene, Zhou et al. describe the mechanisms linking Axl and Met activation to acquired resistance to sunitinib in renal cell carcinoma (RCC), providing a pre-clinical rationale for the development of Axl and Met inhibitors including cabozantinib in anti-angiogenic resistant RCC.

Abstract P2-08-08: Circulating tumor cells count-based nomograms to predict survival of metastatic breast cancer patients: Results from the European pooled analysis

Background: The European Pooled Analysis of CTC (EPAC) in metastatic breast cancer, based on 1,944 individual data from patients with various tumor types and clinical settings (Bidard et al, Lancet Oncol 2014), has established CTC count (CellSearch) at baseline and during therapy as a level of evidence 1 independent prognostic biomarker and demonstrated its superiority over serum blood markers. As part of the study pre-planned objectives, we sought to establish nomograms allowing accurate individual survival predictions.

Methods: Using individual data from 17 centers, we built simplified multivariate prognostic models taking into account the independent prognostic clinico-pathological (CP) characteristics including CTC count, dichotomized using the 5CTC/7.5ml threshold, at baseline and at 3-5 weeks after the start of a new treatment regimen, and derived nomograms for progression-free survival (PFS) and overall survival (OS) prediction at baseline and after 3-5 weeks of treatment. We report here the internal validation of these nomograms. Discrimination of the models was assessed using the c-index estimated by a jackknife procedure and the calibration was visually assessed through 10-fold crossvalidated calibration plots at 1,2,3 years for OS and 1,2 years for PFS.

Results: Multivariate models at baseline for PFS and OS were fitted on 1501 and 568 individual patient data with CTC count at baseline and CTC count at baseline and after 3-5 weeks, respectively. Models include tumor subtype, the number of previous chemotherapy lines (0/1/≥2), PS, age (&lt;=50/&gt;50-65/&gt;65 years), metastasis-free intervals (0/&gt;0-3/&gt;3 years), metastatic sites (liver and CNS) and CTC count at baseline and eventually at 3-5 weeks of treatment. The C-index increased from 0.722 to 0.755 (increase in C-index:0.033, 95% CI [0.019;0.045]) when adding baseline CTC to the CP only model for OS (n=1501). For those patients with CTC values at 3-5 weeks (n=568), there was an additional increase in the C-index when adding CTC at 3-5 weeks to a model with already CP and baseline CTC from 0.731 to 0.743 (increase in C-index 0.013, 95% CI [-0.004;0.025]). The model with CP and baseline CTC counts showed a good calibration for OS at 1,2,3 years and the model with CP, baseline CTC and CTC count at 3-5 weeks a moderately good calibration. Similar results were obtained for PFS.

Conclusion: From the largest database with individual CTC data, we were able to build PFS and OS survival nomograms, with satisfactory discrimination and calibration. Our planned next step is to validate the nomogram in an additional cohort.

Citation Format: Bidard F-C, Peeters D, Fehm T, Nole F, Gisbert-Criado R, Mavroudis D, Grisanti S, Generali D, Garcia-Saenz JA, Stebbing J, Caldas C, Gazzaniga P, Manso L, Zamarchi R, Fernandez de Lascoiti A, de Mattos-Arruda L, Ignatiadis M, van Laere SJ, Meier-Stiegen F, Sandri M-T, Vidal-Martinez J, Politaki E, Consoli F, Bottini A, Diaz-Rubio E, Krell J, Dawson S-J, Raimondi C, Rutten A, Janni W, Munzone E, Carañana V, Agelaki S, Almici C, Dirix L, Solomayer E, Zorzino L, Reis-Filho JS, Squifflet P, Pantel K, Beije N, Sleijfers S, Pierga J-Y, Michiels S. Circulating tumor cells count-based nomograms to predict survival of metastatic breast cancer patients: Results from the European pooled analysis. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-08-08.

Angiosarcoma and Dialysis-related Arteriovenous Fistulae: A Comprehensive Review

OBJECTIVE/BACKGROUND

To conduct a comprehensive review of cases, presentation, diagnosis, and management of angiosarcoma in arteriovenous fistulae (AVF) created for haemodialysis.

METHODS

Two authors independently conducted systematic searches and extraction of articles from the Embase, AMED, Health Management Information Consortium, and MEDLINE databases in keeping with the inclusion/exclusion criteria and Preferred Reporting Items for Systematic Reviews and Meta-Analyses standards.

RESULTS

Twenty-two unique patient cases were identified; 20 of the cases were men and mean ± SD age of presentation was 54.9 ± 13.6 years. Nineteen cases were post-transplant and 18 were on antirejection agents. The most common presenting symptom was pain, with or without a mass. The initial diagnosis was most often thrombosis/infection of the AVF and the diagnostic interval to a correct diagnosis of angiosarcoma was between 2 and 40 weeks. Mean ± SD time to presentation of symptoms from fistula formation was 118.9 ± 57.5 months, while from transplant it was 96.9 ± 70.0 months. Amputation was the most common treatment modality and mean ± SD survival was 8.8 ± 3.7 months.

CONCLUSION

Angiosarcoma should be suspected in previously quiescent AVF that presents with pain. The presence of a rapidly enlarging mass or bleeding/bruising should be taken as alarm indicators and warrant urgent investigation in accordance with local cancer guidelines. Any surgical procedure should involve histological samples as a matter of course.

The impact of adjuvant chemotherapy timing on overall survival following colorectal cancer resection

BACKGROUND

Several studies including two meta-analyses have showed that delay between surgery and adjuvant chemotherapy adversely impacts colorectal cancer survival. This study investigated this impact at a population level over a fifteen year period in England.

METHODS

The Hospital Episode Statistics database was analysed between 1997 and 2012. Colonic cancer and rectal cancer patients were collated and multivariate Cox regression analyses were undertaken to ascertain the relationship between chemotherapy delay and overall survival.

RESULTS

A total of 181 984 patients underwent resection without any reoperation (106 477 (58.5%) having colonic cancer and 75 507 (41.5%) having rectal cancer). In total, 30 836 (16.9%) received adjuvant chemotherapy. 9019 (49.3%), 4573 (25.0%), 2587 (14.1%), 1323 (7.2%) and 804 (4.4%) of 18 306 colonic cancer patients received within 8 weeks, 8-10 weeks, 10-12 weeks, 12-14 weeks and 14-16 weeks, respectively. Sequentially worse overall survival was observed: <8 weeks: Ref; 8-10 wks: Hazard Ratio (HR) 1.09; 10-12 wks: HR 1.13; 12-14 wks HR 1.32 and 14-16 wks: HR 1.32, p < 0.001. 5625 (44.9%), 3087 (24.6%), 1940 (15.5%), 1162 (9.3%) and 716 (5.7%) of 12 530 rectal cancer patients received within 8 weeks, 8-10 weeks, 10-12 weeks, 12-14 weeks and 14-16 weeks, respectively. Sequentially worse overall survival was observed: <8 weeks: Ref; 8-10 wks: HR 1.09; 10-12 wks: HR 1.22; 12-14 wks HR 1.23 and 14-16 wks: HR 1.31, p < 0.001.

CONCLUSION

Adjuvant chemotherapy delay adversely impacts colonic and rectal cancer survival. Efforts to prevent complications such as reoperation and to improve access to chemotherapy services, will improve survival in this patient cohort.

Epigenetic changes in gastroenteropancreatic neuroendocrine tumours

An understanding of epigenetic drivers of tumorigenesis has developed rapidly during the last years. The identification of these changes including DNA methylation and histone modifications in gastroenteropancreatic neuroendocrine tumours (GEP-NETs) is a step forward in trying to define underlying biologic processes in this heterogeneous disease. The reversible nature of these changes represents a potential therapeutic target. We present an overview of the current knowledge of epigenetic alterations related to GEP-NETs, focusing on the influence and impact these changes have on pathogenesis and prognosis. The potential role of demethylating agents in the management of this patient population is discussed.

When does a human being die?

For most of human history there has been no particular importance of establishing the exact time of a person's death, only whether the person is alive or dead. With modern medical advances, however, more precise answers are looked for. For a definition of death to succeed is important that it is a universal definition and that under it, all human beings are correctly identified as alive or dead. This article initially examines the most commonly proposed positions on when a human being dies those of cardiopulmonary death, whole brain death, brainstem death and higher brain death and for each describes scenarios that provide counter-intuitive results. Intuition is used as a benchmark as this is what our patients most commonly use. The second part of the article seeks to establish a more robust definition of death. We argue that death is an event that takes place at a set point in time, when the collection of bodily processes that maintains homoeostasis finally cease. Based upon defining 'human being' as being in possession of human DNA and Olsen's Animalism, the model is applicable to a full lifespan and maintains personal identity throughout the course of life. That this conclusion will interfere with clinical practice concerning organ transplantation is considered, but countered with the argument that there has been a conflation of the normative question of timing of organ retrieval for transplantation with the metaphysical question of what is death.

Genetic variants of kinase suppressors of Ras (KSR1) to predict survival in patients with ERα-positive advanced breast cancer

In patients with breast cancer (BC), deregulation of estrogen receptor (ERα) activity may account for most resistance to endocrine therapies. Our previous study used a whole-human kinome siRNA screen to identify functional actors in ERα modulation and showed the implication of proteins kinase suppressors of ras (KSR1). From those findings we evaluated the clinical impact of KSR1 variants in patients with ERα+ BC treated with TAM. DNA was obtained from 222 patients with advanced ERα+ BC treated with TAM who had undergone surgery from 1981 to 2003. We selected three potentially functional relevant KSR1 polymorphisms; two within the 3'UTR (rs224190, rs1075952) and one in the coding exon 7 (rs2293180). The primary end points were overall survival (OS) and disease-free survival (DFS). After a 6.4-year median follow-up, patients carrying the rs2241906 TT genotype showed shorter DFS (2.1 vs 7.1 years, P=0.005) and OS (2.6 vs 8.4 years P=0.002) than those with the TC or TT genotypes. Those associations remained significant in the multivariable analysis adjusting age, lymph node status, LMTK3 and IGFR variants and HER2 status. The polymorphisms rs2241906 and rs1075952 were in linkage disequilibrium. No association was shown between rs2293180 and survival. Among the actors of ERα signaling, KSR1 rs2241906 variants may predict survival in patients with advanced ERα+ BC treated with adjuvant TAM.

Myocardial MiR-30 downregulation triggered by doxorubicin drives alterations in β-adrenergic signaling and enhances apoptosis

The use of anthracyclines such as doxorubicin (DOX) has improved outcome in cancer patients, yet associated risks of cardiomyopathy have limited their clinical application. DOX-associated cardiotoxicity is frequently irreversible and typically progresses to heart failure (HF) but our understanding of molecular mechanisms underlying this and essential for development of cardioprotective strategies remains largely obscure. As microRNAs (miRNAs) have been shown to play potent regulatory roles in both cardiovascular disease and cancer, we investigated miRNA changes in DOX-induced HF and the alteration of cellular processes downstream. Myocardial miRNA profiling was performed after DOX-induced injury, either via acute application to isolated cardiomyocytes or via chronic exposure in vivo, and compared with miRNA profiles from remodeled hearts following myocardial infarction. The miR-30 family was downregulated in all three models. We describe here that miR-30 act regulating the β-adrenergic pathway, where preferential β1- and β2-adrenoceptor (β1AR and β2AR) direct inhibition is combined with Giα-2 targeting for fine-tuning. Importantly, we show that miR-30 also target the pro-apoptotic gene BNIP3L/NIX. In aggregate, we demonstrate that high miR-30 levels are protective against DOX toxicity and correlate this in turn with lower reactive oxygen species generation. In addition, we identify GATA-6 as a mediator of DOX-associated reductions in miR-30 expression. In conclusion, we describe that DOX causes acute and sustained miR-30 downregulation in cardiomyocytes via GATA-6. miR-30 overexpression protects cardiac cells from DOX-induced apoptosis, and its maintenance represents a potential cardioprotective and anti-tumorigenic strategy for anthracyclines.

KSR1 regulates BRCA1 degradation and inhibits breast cancer growth

Kinase suppressor of Ras-1 (KSR1) facilitates signal transduction in Ras-dependent cancers, including pancreatic and lung carcinomas but its role in breast cancer has not been well studied. Here, we demonstrate for the first time it functions as a tumor suppressor in breast cancer in contrast to data in other tumors. Breast cancer patients (n>1000) with high KSR1 showed better disease-free and overall survival, results also supported by Oncomine analyses, microarray data (n=2878) and genomic data from paired tumor and cell-free DNA samples revealing loss of heterozygosity. KSR1 expression is associated with high breast cancer 1, early onset (BRCA1), high BRCA1-associated ring domain 1 (BARD1) and checkpoint kinase 1 (Chk1) levels. Phospho-profiling of major components of the canonical Ras-RAF-mitogen-activated protein kinases pathway showed no significant changes after KSR1 overexpression or silencing. Moreover, KSR1 stably transfected cells formed fewer and smaller size colonies compared to the parental ones, while in vivo mouse model also demonstrated that the growth of xenograft tumors overexpressing KSR1 was inhibited. The tumor suppressive action of KSR1 is BRCA1 dependent shown by 3D-matrigel and soft agar assays. KSR1 stabilizes BRCA1 protein levels by reducing BRCA1 ubiquitination through increasing BARD1 abundance. These data link these proteins in a continuum with clinical relevance and position KSR1 in the major oncoprotein pathways in breast tumorigenesis.

1000 Port-A-Cath ® placements by subclavian vein approach: single surgeon experience

INTRODUCTION

Totally implantable venous access ports are widely used for the administration of chemotherapy in patients with cancer. Although there are several approaches to implantation, here we describe Port-A-Cath(®) (PAC) placement by percutaneous puncture of the subclavian vein with ultrasonographic guidance.

PATIENTS AND METHODS

Data on our vascular access service were collected prospectively from June 2004. This service included port-a-caths and Hickman lines. Once 1000 consecutive port-a-caths(®) had been reached the study was closed and data analysed for the port-a-caths(®) alone. The left subclavian vein was the preferred site for venous access, with the right subclavian and jugular veins being the alternative choices if the initial approach failed. Patients were followed up in the short-term, and all the procedures were carried out by a single surgeon at each one of two institutions.

RESULTS

Venous access by PAC was established in 100 % of the 1,000 cases. Of the 952 patients where the left subclavian vein was chosen for the first attempt of puncture, the success rate of PAC placement was 95 % (n = 904). Pneumothorax occurred in 12 patients (1.2 %), and a wound haematoma occurred in 4 (0.4 %) out of the total 1,000 patients. No infections were recorded during the immediate post-operative period but only in the long-term post-operative use with 8 patients requiring removal of the PAC due to infection following administration of chemotherapy.

CONCLUSION

This is a very large series of PAC placement with an ultrasound-guided approach for left subclavian vein and X-ray confirmation, performed by a single surgeon, demonstrating both the safety and effectiveness of the procedure.

Dynamic changes of the inflammation-based index predict mortality following chemoembolisation for hepatocellular carcinoma: a prospective study

BACKGROUND

Transarterial chemoembolisation (TACE) is a standard treatment for unresectable, intermediate stage hepatocellular carcinoma (HCC). Survival after TACE, however, can be highly variable, with no suitable biomarker predicting therapeutic outcome. The inflammation-based index (IBI) has previously been shown to independently predict overall survival (OS) in all stages of HCC.

AIM

To explore the prognostic ability of IBI as a predictor of survival after TACE.

METHODS

Baseline staging, biochemical and clinicopathological features including IBI were studied in a derivation set of 64 patients undergoing TACE for intermediate stage HCC. Dynamic changes in IBI before and after TACE were studied as predictors of survival using both a univariate and multivariate Cox regression model and further validated in two independent patient cohorts from Korea (n = 76) and Japan (n = 577).

RESULTS

Pre-treatment IBI predicted for OS in the derivation set (P = 0.001). Other univariate predictors of OS included radiological response to TACE (P < 0.001), pre-TACE CLIP score (P < 0.01), tumour diameter >5 cm (P = 0.05) and AFP ≥400 (P < 0.001). Normalisation of IBI post-TACE was associated with radiological response by mRECIST criteria and improved OS (P < 0.001). Normalisation of IBI remained a significant multivariate predictor of OS in both the derivation and validation sets (P < 0.001).

CONCLUSIONS

Normalisation of IBI after TACE is shown to be an independent predictor of survival and may be integrated into the retreatment criteria for repeat TACE in intermediate stage HCC. IBI and its dynamic changes after treatment are validated as a biomarker allowing the stratification of patients with a significant survival advantage following initial TACE.

Combined PKC and MEK inhibition for treating metastatic uveal melanoma

Uveal melanoma (UM) is the most common primary intraocular malignancy and the second most common form of melanoma. UM has a strong tendency for metastatic disease, and no effective treatments have yet been identified. Activating oncogenic mutations are commonly found in GNAQ and GNA11 in UM, and inhibiting key downstream effectors of the GNAQ/11 signaling pathway represents a rational therapeutic approach for treating metastatic UM. Chen et al., doi:10.1038/onc.2013.418, now confirm activation of the MAPK and PKC pathways as a result of GNAQ and GNA11 activating mutations in melanocytes, and they demonstrate that MAPK activation occurs downstream of PKC activation. PKC inhibitors disrupt MAPK signaling and block proliferation of GNAQ/11 mutant UM cell lines and slow the in vivo growth of xenografted UM tumors without inducing their shrinkage. However, a combination of PKC and MEK inhibition led to sustained MAPK pathway inhibition and tumor regression in vivo. Hence, the authors concluded that MEK and PKC inhibition is synergistic, with superior efficacy to treatment of GNAQ/GNA11 mutant UMs with either drug alone.