NRAS Mutation Status Research Articles

Mutation analysis and genomic imbalances of cells found in effusion fluids from patients with ovarian cancer.

Ovarian carcinomas and carcinosarcomas often cause malignant effusions, an accumulation within serous cavities of fluid containing cancer cells. Few studies have focused on the molecular alterations and genetic mechanisms behind effusion formation. The present study investigated the mutation status of TP53, PIK3CA, KRAS, HRAS, NRAS and BRAF in effusion fluids from 103 patients with ovarian cancer. In addition, array Comparative Genomic Hybridization (aCGH) analysis was performed on 20 effusions from patients with high-grade serous carcinoma (10 cases positive for TP53 mutation and 10 with TP53 wild-type). TP53 mutations, two of which were novel: c.826_830delCCTGT and c.475_476GC>TT, were identified in 44% of the cases. Mutations in KRAS, HRAS, and PIK3CA were identified in two, two and four cases, respectively. None of the effusions analysed showed NRAS or BRAF mutations. The aCGH analysis revealed highly imbalanced genomes similar to those described in primary ovarian carcinomas. No specific profile was indicated to distinguish tumors with TP53 mutations from those without. The molecular profiling of cells found in effusion fluids from patients with ovarian cancer thus showed considerable molecular heterogeneity. TP53 seems to be the most frequently mutated gene in these cells and may serve a leading role in the metastatic process.

Second primary melanoma in advanced melanoma patients treated with anti-PD-1 monoclonal antibodies.

e22025 Background: Development of a second primary melanoma (SCPM) has not been reported in melanoma patients treated with anti-PD-1 monoclonal antibodies (mAb), in contrast with those reported in BRAF-inhibitor-treated patients. Our aim was to report arising SCPM in patients with advanced melanoma treated with anti-PD-1 therapy. Methods: Retrospective study, conducted in 2 referral centres, including advanced melanoma patients who developed a SCPM after anti-PD-1 mAb initiation, between September 2010 and May 2019. BRAF or NRAS mutational status was assessed by targeted NGS panels, real-time PCR, and immunohistochemistry. Results: Among a total of 509 patients treated with anti-PD-1 mAb, 4 had a SCPM (incidence: 0.8%; 95%CI: 0.02-1.57%). All patients were treated with nivolumab, in first (N = 3) or second line after progression with BRAF + MEK inhibitors (N = 1). No immune-related adverse event greater than grade 2 according to Common Terminology Criteria for Adverse Events version 5.0. was observed in these 4 cases; a vitiligo-like depigmentation (grade 1) was observed in two patients. The median time from the first nivolumab infusion to the SCPM diagnosis was 17.5 months (range: 5-21). All patients developed the SCPM after achieving a complete response. Nivolumab administration had been discontinued (4 months prior) in one patient. Histology revealed 4 superficial spreading melanomas (SSM): one invasive (without BRAFV600 mutation) and 3 intraepidermal melanomas (2 with a BRAFV600E mutation and one with a NRASQ61H mutation). 3 patients had risk factors for developing multiple melanomas: a dysplastic nevus syndrome, a high number of nevi (≥100 nevi), and a family history of melanoma in first-degree relatives and constitutional heterozygous mutation of exon 2 of the CDKN2A gene. Occurrence of SPCM did not alter advanced melanoma treatment. With a median follow-up of 29 months [range: 18-41] from the first anti-PD-1 mAb infusion, all patients had prolonged CR, and treatment was discontinued in all patients, without relapse after a median 11.5 months [0-18] off therapy. The median duration of nivolumab treatment was 15.5 months [10-24]. Conclusions: Although anti-PD-1 mAb could theoretically decrease the risk of developing another melanoma in metastatic melanoma patients, we found 4 such cases, highlighting the importance of regular clinical screenings for new primary melanoma in patients with metastatic melanoma even when responsive to anti-PD-1 therapy. Immune checkpoint inhibitors do not totally prevent the risk of occurrence a SCPM.

A multi-institution analysis of molecular biomarkers in patients with metastatic colorectal cancer in ethnically diverse populations.

e16074 Background: Differences in clinical outcomes for metastatic CRC (mCRC) have been reported across racial-ethnic groups, particularly between Hispanics (HA), non-Hispanic Blacks (NHB), and non-Hispanic Whites (NHW), with limited information available among Asian Americans (AA). We examined if there were differences in clinical outcomes by molecular drivers between these groups in a pooled analysis of two institutions serving ethnically diverse patient populations. Methods: We retrospectively examined 1927 mCRC patients from Montefiore Medical Center and the University of Texas MD Anderson Cancer Center. Mutations in KRAS, NRAS, and BRAF were determined by polymerase chain reaction or next generation sequencing. Mutations were then correlated with overall survival (OS). Results: Our patient population consisted of 1153 (61%) NHW, 314 (17%) HA, 320 (17%) NHB and 59 (3.1%) AA. Across subgroups, borderline significant difference in prevalence of BRAF mutation was observed (p = 0.04), with higher prevalence observed among NHW as compared to other groups. No differences were observed for KRAS and NRAS mutation prevalence. In univariate analysis, the median survival for BRAF MT tumors was 18.5 months vs 32 months for BRAF WT tumors (p < 0.0001). Similarly, median OS for KRAS WT, KRAS MT, NRAS WT and NRAS MT was 29.3, 27.4, 31 and 31.5 months respectively, with no differences between groups. In subgroup analysis by race/ethnicity, median OS in BRAF MT NHW was 19.98 months vs 33.48 in BRAF WT NHW (p < 0.0001). Similar trends were observed in HA and NHB. No differences in median OS were observed by KRAS or NRAS mutation status across racial-ethnic groups. Conclusions: This multi-institution study found no meaningful difference in the prevalence of molecular drivers across racial-ethnic groups. Additionally, in our subgroup analyses, OS based on the presence of a specific molecular driver mutation did not seem to vary by race. For example, RAS mutated and BRAF mutated patients showed similar OS across racial-ethnic groups. Our study demonstrates that reported differences in clinical outcomes by race and ethnicity in the literature are unlikely to be dependent on the difference in the presence of certain molecular drivers.

Treatment effects (TEs) of EGFR monoclonal antibodies (mAbs) in metastatic colorectal cancer (mCRC) patients (pts) with KRAS, NRAS, and BRAF mutation (MT) status: Individual patient data (IPD) meta-analysis of randomized trials from the ARCAD database.

4090 Background: EGFR mAbs have become incorporated into clinical practice for the management of mCRC over the last decade. KRAS and NRAS mutations are used as predictive biomarkers and BRAF V600E mutations are associated with an adverse prognosis. The observed TE within biomarker subpopulations has varied between studies. Methods: IPD from randomized trials with head-to-head comparison between EGFR mAb versus no EGFR mAb (chemotherapy alone or BSC) in mCRC, across all lines of therapy (first, second and later), were pooled. Biomarker subpopulations are defined in the table. Overall survival (OS) and progression-free survival (PFS) were compared between groups by Cox model, stratified by studies and adjusted by age, gender, and performance status. TEs were estimated by adjusted hazard ratio (HRadj) and 95% confidence interval (CI). Within each biomarker subgroup, EGFR mAb efficacy was explored according to multiple exploratory factors, including line of therapy, type of backbone chemo, gender, sidedness and site of metastasis. Interaction tests were performed. P-values < 0.01 were considered statistically significant to account for multiple comparisons. Results: 5729 pts from 8 studies with data available for ≥ 1 biomarker were analysed. PFS benefits (median 9.2 mos in EGFR mAbs, 8.0 mos in no EGFR mAbs) were confirmed in triple-WT pts, but not for OS (refer to table). No OS/PFS benefits were observed for pts with any of the MT tumors. Exploratory analyses showed a potential detrimental TE of EGFR mAbs in KRAS MT mCRC with liver metastasis (OS: HRadj 1.22, p = .003, pinteraction .0056; PFS: HRadj 1.24, p = .0009, pinteraction .0008). These results were confirmed within the subgroup of pts with all 3 biomarkers available. Conclusions: This is the largest IPD analysis to explore the predictive value of RAS/BRAF biomarkers in mCRC. Our findings demonstrate that there is no evidence of efficacy of EGFR mAbs in KRAS, BRAF and/or NRAS MT mCRC. EGFR mAbs might have a detrimental effect in KRAS MT mCRC with liver metastases. [Table: see text]

BRAF, KIT, and NRAS Mutations of Acral Melanoma in White Patients.

Malignant acral melanoma (AM) is relatively infrequent in white patients. Molecular investigations have returned variable results regarding the mutational pattern. We sought to describe the mutation profile and clinicopathologic features of AM. We investigated BRAF, KIT, and NRAS mutational status in a series of 31 AM samples from white patients. Nodular melanoma was the most common histopathologic subtype (48.4%), followed by acral lentiginous melanoma (25.8%) and superficial spreading melanoma (25.8%). BRAF, KIT, and NRAS mutational rates were 12.9%, 17.2%, and 30.0%, respectively. We observed significant associations between KIT mutational status and a thinner Breslow thickness compared with wild-type (WT) status (P = .002), NRAS mutation status and younger age compared with WT. In patients presenting at least one mutation, triple-WT patients presented metastases most frequently. Although these data represent preliminary results, better knowledge of tumor biology and prognosis of AM can support the clinical approach and follow-up.

Intra-patient Heterogeneity of BRAF and NRAS Molecular Alterations in Primary Melanoma and Metastases.

Mutations in MAPK signalling genes are driver events in melanoma, and have therapeutic relevance in the metastatic and adjuvant setting. This study evaluated the intra-patient heterogeneity of BRAF, NRAS and c-KIT mutational status between 30 primary melanomas and 39 related metastases, using molecular analysis and immunohistochemistry. BRAF mutations were identified in 46.7% of primary melanomas and 48.7% of metastases and NRAS mutations in 20% and 25.6%, respectively. Intra-patient heterogeneity was detected in 13.3% of patients for both BRAF and NRAS genes and was not associated with clinico-pathological characteristics of melanomas or metastases. High consistency was observed between immunostaining and molecular methods for BRAFV600E (k = 0.90; p < 0.001) and NRASQ61R (k = 0.87; p < 0.001). These findings demonstrate a relevant intra-patient heterogeneity between primary and metastatic lesions that is independent of clinical variables and methodological approach.

Mutational Profile of Driver Genes in Brazilian Melanomas.

PURPOSEMutation testing of the key genes involved in melanoma oncogenesis is now mandatory for the application of targeted therapeutics. However, knowledge of the mutational profile of melanoma remains largely unknown in Brazil.PATIENTS AND METHODSIn this study, we assessed the mutation status of melanoma driver genes BRAF, NRAS, TERT, KIT, and PDGFRA in a cohort of 459 patients attended at Barretos Cancer Hospital between 2001 and 2012. We used polymerase chain reaction followed by Sanger sequencing to analyze the hot spot mutations of BRAF exon 15 (V600E), NRAS (codons 12/13 and 61), TERT (promoter region), KIT (exons 9, 11, 13, and 17), and PDGFRA (exons 12, 14, and 18) in tumors. The mutational profile was investigated for associations with demographic, histopathologic, and clinical features of the disease.RESULTSThe nodular subtype was most frequent (38.9%) followed by the superficial spreading subtype (34.4%). The most frequent tumor location was in the limbs (50.0%). The mutation rates were 34.3% for TERT and 34.1% for BRAF followed by NRAS (7.9%), KIT (6.2%), and PDGFRA (2.9%). The BRAF (P = .014) and TERT (P = .006) mutations were associated with younger patients and with different anatomic locations, particularly in the trunk, for the superficial spreading and nodular subtypes, respectively (P = .0001 for both). PDGFRA mutations were associated with black skin color (P = .023) and TERT promoter mutations with an absence of ulceration (P = .037) and lower levels of lactate dehydrogenase. There was no association between patient survival rates and mutational status.CONCLUSIONThe similar mutational profile we observe in melanomas in Brazil compared with other populations will help to guide precision medicine in this country.

1377TiP - A phase Ia/Ib clinical study to evaluate the safety, pharmacokinetics (PK) and preliminary anti-tumour activity of FCN-159 in patients with advanced melanoma harboring NRAS-aberrant (Ia) and NRAS-mutation (Ib)

BackgroundGain of function mutations in NRAS occurs in 15-25% of patients with melanoma, leading to activation of Ras/Raf/MEK/ERK signaling pathway results in unconstrained cell growth and cell transformation. The MEK inhibitor targets this signaling pathway, inhibiting cell proliferation and inducing apoptosis. NRAS mutation status was identified as an independent poor prognostic factor in stage IV melanoma. It is also reported that the survival of patients with high copy number (>4) was significantly worse than that of NRAS patients with 2-4 copy number (P=0.002). No drug was approved to treat melanoma patients with NRAS mutation or amplification until now. FCN-159, an oral and potent MEK1/2 inhibitor, has more than 10 folds higher selectivity against activated MEK1 and MEK2 compared with trametinib, and has demonstrated significant antitumor growth inhibition in two patient-derived xenograft (PDX) models with NRAS mutation. This is the first in human study to evaluate the safety and anti-tumor activity of FCN-159 in patients. Trial designThis is a phase Ia/Ib, open label, dose-escalation study with expansion cohort that will evaluate the safety, pharmacokinetics (PK), and preliminary anti-tumor activity of FCN-159 in up to 37 patients with locally advanced or metastatic melanoma harboring NRAS-aberrant including both NRAS amplification and mutation (Ia) and NRAS-mutation only (Ib). In this study, the dose escalation utilizes 3+3, accelerated titration design with starting dose of 0.2mg, QD, orally; the dose will be escalated until Maximum-Tolerated Dose (MTD) or the Recommended phase II dose (RP2D) being identified. The dose level will be considered to expand up to 6 patients if an objective response is observed, intending to collect more clinical data to support the RP2D determination. Once the MTD or RP2D is identified, an expansion cohort will be followed to further evaluate the safety and efficacy of FCN-159 in patients with NRAS-mutant melanoma. As of April 22, 2019, one patient has been dosed. Legal entity responsible for the studyShanghai Fosun Pharmaceutical Development Co, Ltd. FundingShanghai Fosun Pharmaceutical Development Co, Ltd. DisclosureAll authors have declared no conflicts of interest.

1344P - Outcomes of advanced melanoma patients who discontinued pembrolizumab (pembro) after complete response (CR) in the French early access program (EAP)

BackgroundInformation on outcomes after cessation of anti-PD-1 mAb for CR are scarce outside KN-001 & 006 trials. We investigated these outcomes in the French pembro EAP, where pts were less selected than in registration trials. MethodsA multicenter ambispective cohort of advanced melanoma pts initiating pembro between May 2014-Sept 2015 (CCTIRS, #15.640) was searched for pts who achieved CR. Overall and progression-free survivals with Log rank tests were used to compare curves. Results687 pts (159 with brain metastases) were included from 41 centers, which covered 75% of French pembro EAP. 79 pts (13%) achieved CR, among whom 68 (10%) stopped pembro for CR. Compared with the remaining 619 pts surveyed, these 68 pts had lower baseline serum LDH levels (54.5% vs 73.8%, respectively, were normal, p=0.016), lower ECOG PS (ECOG 0 for 298 (52.6%) and 54 (80.6%), respectively, p=0.001), and fewer metastatic sites (p=0.003). Of note, 10% of these 68 pts had >3 metastatic sites, 10% had brain metastases, 53% had 2010 AJCC stage M1c melanoma, and 67% had received previous treatment for advanced melanoma (mainly ipilimumab). Frequency of BRAFV600, NRAS, and c-kit mutation status was not different between pts who did or did not achieve CR. Median duration on pembro in these 68 pts was 21.2 m (range: 2.5-48.4, SD 10.0). Pembro was used alone to achieve CR in 79% of pts, while 4% received concurrent radiotherapy alone, 10% concurrent surgery alone, and 6% both treatments. At the cut-off date (13/09/2018), after a median follow-up since pembro initiation of 36.3 m and of 15.3 m since pembro cessation (2-31, SD 8.3), only 3% of pts experienced melanoma recurrence. Median recurrence-free survival was not achieved. These 2 pts received radiotherapy, with one partial response achieved. 5 pts died, with 2 deaths unrelated to melanoma (1 lymphoma, 1 chylothorax), 1 related to melanoma progression, and 2 of unknown causes. ConclusionsIn this large real-life cohort, 10% of pts reached CR and discontinued pembro. All but 3% were recurrence-free after a median 15.3 m of treatment, thus validating the discontinuation of anti-PD1 in complete responders. Clinical trial identificationCCTIRS, #15.640. Editorial acknowledgementRIC-Mel network and their team. Legal entity responsible for the studyMSD France. FundingMSD France. DisclosureP. Saiag: Honoraria (self), Advisory / Consultancy: MSD. L. Mortier: Honoraria (self), Advisory / Consultancy: MSD. C. Dutriaux: Honoraria (self), Advisory / Consultancy: MSD. L. Benmahammed: Full / Part-time employment: MSD. O. Morsli: Full / Part-time employment: MSD. C. Train: Full / Part-time employment: ClinSearch. A. Spampinato: Full / Part-time employment: MSD. M.T. Leccia: Honoraria (self), Advisory / Consultancy: MSD. N. Meyer: Advisory / Consultancy: MSD. J.J. Grob: Honoraria (self), Advisory / Consultancy: MSD.

Sequencing of RAS/RAF pathway genes in primary colorectal cancer and matched liver and lung metastases

BackgroundMutations in the RAS/RAF pathway predict resistance to anti-epidermal growth factor receptor antibodies in colorectal cancer (CRC), and may be targets for future therapies. This study investigates concordance of BRAF, HRAS, KRAS, NRAS and PIK3CA mutation status in primary CRC with matched liver (n = 274), lung (n = 114) or combined liver and lung metastases (n = 14).MethodsNext generation sequencing was performed on DNA from formalin-fixed paraffin embedded CRC and matched liver and/or lung metastases, for recurrent mutations in BRAF, HRAS, KRAS, NRAS and PIK3CA and using the single-molecule molecular inversion probe method.ResultsPaired sequencing results on all five genes were reached in 249 of the 402 cases (62%). The obtained number of unique reads was not always sufficient to confidently call the absence or presence of mutations for all regions of interest. The mutational status of matched pairs was highly concordant; 91.1% concordance for all five genes, 95.5% for KRAS, 99.1% for NRAS. Lung metastases more often harboured RAS mutations compared to liver metastases (71% vs. 48%, p < 0.001).ConclusionsIn this large series of CRC we show that both primary tumors and corresponding metastases can be used to determine the mutational status for targeted therapy, given the high concordance rates. Next generation sequencing including a single molecule tags is feasible, however in combination with archival formalin-fixed paraffin embedded material is limited by coverage depth.

Analysis of KRAS and NRAS mutations in Greek patients with metastatic Colorectal Cancer (mCRC) on the registry of the Gastro-intestinal Cancer Study Group (GIC-SG)

Abstract Introduction Several studies show that mutational profiles could influence treatment decisions in patients with metastatic CRC (mCRC). KRAS mutational status was the first step in biomarkers development in the era of molecular targeted therapies. Recently, NRAS mutational status was identified as an independent prognostic factor for the response to treatment with anti-EGFR moAbs. The aim of this observational study was to assess the feasibility of the KRAS/NRAS mutational analysis in patients with metastatic colorectal cancer in Greece and to identify any correlations with known clinical characteristics and histopathologic features. Methods From January 2014 until September 2014 all patients registered to the GIC-SG database with newly diagnosed metastatic disease from colon or rectal cancer were included and tumor samples were analyzed for kras/nras mutations in 9 different certified laboratories in Greece. Results Samples from 510 patients were analyzed. Mutations’ distribution was as follows: 173 (33,9%) KRAS exon 2, 10 (2%) KRAS exon 3, 25 (4,9%) KRAS exon 4, 22 (4,3%) NRAS exon 2, 11 (2,2%) NRAS exon 3 and 3 (0,6%) NRAS exon 4. The only factor significantly associated with RAS mutational status was primary tumor location, with right sided tumors exhibiting higher rates of mutations. Discussion The incidence and distribution of KRAS or NRAS exon 2-4 mutations are in accordance with those reported in the literature. The most significant clinical or pathological parameter revealed from the analysis is the location of the primary tumor.

Primary malignant melanoma of esophagus: clinicopathologic characterization of 20 cases including molecular genetic profiling of 15 tumors

Primary malignant melanoma of esophagus is very rare, and its clinicopathologic and genetic features have not been extensively investigated. In this study, 20 tumors from 14 male and 6 female patients (40–79 years old) were evaluated. Dysphagia, chest pain, and weight loss were frequent symptoms. Thirteen melanomas, including two with multiple lesions, involved the distal third of esophagus. The median tumor diameter was 6 cm. Epithelioid morphology, moderate atypia, and pigmentation were typical findings. None of the patients had melanoma elsewhere, and all tumors exhibited a junctional peri-epithelial component consistent with a primary lesion. The median mitotic activity was 11 per 10 high-power fields (range, 0–31). Nine patients died of tumor within 4–22 months, however, two showed long-term (96 and 104 months) survival. In 15 cases, tissue for further immunohistochemical and molecular studies were available. BRAF, KIT, and NRAS mutation status was assessed by Sanger sequencing in all 15 tumors. The next-generation sequencing of 50 or 409 genes was performed in five and three cases, respectively. IGF1R expression indicating activation of the IGF axis was seen in 82% (9/11) of tumors. However, no BRAF mutations were identified. In 33% (5/15) of tumors, NRAS mutations were detected. KIT expression was seen in 50% (7/14) of melanomas including single KIT mutant. Two of three tumors evaluated with 409 genes panel revealed multiple driver mutations indicating sub-clonal expansion, whereas a single mutation (TSC1 p.H371Q) was the sole change in the third case. SF3B1 p.K666T and p.R625C mutations were detected in two cases. However, no co-occurrence of SF3B1 and GNAQ or GNA11 mutations, seen in uveal melanoma, was detected. FBXW7 p.R465C and p.R479G mutations, linked to cancer progression, were found in two of eight tumors. In summary, esophageal melanoma mutation profile indicates complexity of molecular mechanisms underlying its pathogenesis.

Abstract 2085: Treatment of human melanoma cells with dasatinib requires inactivation of both mTOR and MAPK pathways to achieve high cell eradication efficacy

Abstract Advanced stages of melanoma are resilient to therapy and new strategies for the treatment are required. About 60% of melanomas harbor the mutated BRAF oncogene, which activate the MAPK pathway. This BRAF driver mutation can be targeted by a small molecule drug vemurafenib. However, most of patients develop resistance during treatment and even drug addiction is acquired. The nonreceptor SRC tyrosine kinase is highly expressed and deregulated in melanoma and can be efficiently inhibited by the inhibitor dasatinib, an anticancer drug which is already used for the treatment of some tumor types. SRC does not have its own canonical pathway but is capable of activating and augmenting different signaling routes in cancer cells. We found that melanoma tumor cell lines analysed were generally resistant to dasatinib irrespective of BRAF or NRAS mutational status. The exception was the cell line Hbl which was very sensitive even to low dasatinib doses and Hbl cells were completely eradicated by 10 nM of dasatinib in several days. The sensitivity of Hbl to dasatinib was dependent on the drug ability to inhibit completely both the MAPK and AKT/mTOR signaling pathways. Dasatinib was capable of inhibiting SRC activation resulting in the repression of AKT activation in Hbl cells. AKT phosphorylation at Ser473 was fully abolished and Thr308 was severely attenuated through inhibiting SRC by dasatinib in Hbl cells. These two phosphorylations are required for AKT activity. MAPK pathway (ERK1/2 phosphorylation) was also inhibited in Hbl cells. Dasatinib also inhibited the phosphorylation of SRC at Tyr416 (a hallmark of SRC activity) in Hbl cells and, surprisingly, also in other dasatinib-resistant melanoma cells. Importantly, although SRC was dephosphorylated at Tyr416, dasatinib was unable to inactivate AKT and MAPK pathway (ERK1/2) in all other melanoma cells. Molecular changes closely correlated with proliferation assays. Our data indicate that the combination therapy of melanoma with dasatinib would bring benefit to patients only by blocking both MAPK and AKT signaling pathways in melanoma cells. Altogether, more molecular knowledge of the effects of the powerful anticancer drug dasatinib is required in order to be used for the treatment of melanoma. This work was supported by the Institutional research project PROGRESQ25 from Charles University Prague. Citation Format: Jiri Vachtenheim, Jiri Réda, Kateřina Vlčková, Lubica Ondrušová. Treatment of human melanoma cells with dasatinib requires inactivation of both mTOR and MAPK pathways to achieve high cell eradication efficacy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2085.

Melanoma proteomics suggests functional differences related to mutational status

Melanoma is the most lethal cutaneous cancer. New drugs have recently appeared; however, not all patients obtain a benefit of these new drugs. For this reason, it is still necessary to characterize melanoma at molecular level. The aim of this study was to explore the molecular differences between melanoma tumor subtypes, based on BRAF and NRAS mutational status. Fourteen formalin-fixed, paraffin-embedded melanoma samples were analyzed using a high-throughput proteomics approach, combined with probabilistic graphical models and Flux Balance Analysis, to characterize these differences. Proteomics analyses showed differences in expression of proteins related with fatty acid metabolism, melanogenesis and extracellular space between BRAF mutated and BRAF non-mutated melanoma tumors. Additionally, probabilistic graphical models showed differences between melanoma subgroups at biological processes such as melanogenesis or metabolism. On the other hand, Flux Balance Analysis predicts a higher tumor growth rate in BRAF mutated melanoma samples. In conclusion, differential biological processes between melanomas showing a specific mutational status can be detected using combined proteomics and computational approaches.

Combined detection of KRAS, NRAS, BRAF and PIK3CA mutations in the plasma and tumor tissues of colorectal cancer patients

Objective: To analyze the concordance of KRAS, NRAS, BRAF and PIK3CA gene mutations detected in plasma and matched tumor tissues in colorectal cancer patients, in order to provide good evidences to support plasma could be a potential surrogate of tumor tissue for gene mutation test. Methods: One hundred and seventy-five cases of colorectal cancer were collected at the First Hospital of Jilin University, from October 2016 to October 2017.There were 101 males and 74 females, their ages ranged from 28 to 85 years,with median age of 59 years. The KRAS, NRAS, BRAF and PIK3CA gene mutations in the plasma and paired tumor specimens of all patients were detected by next generation sequencing. Results: The results of tissue samples test were gold standard. Comparison of the four genes showed that concordance rates between plasma and tissue samples were 81.1%(Kappa=0.543), 99.4%(Kappa=0.886), 99.4% (Kappa=0.886) and 97.7%(Kappa=0.714) respectively for KRAS, NRAS, BRAF and PIK3CA. The plasma detection rates of these genes were related to tumor stage(P=0.001), but not to gender(P=0.468) and age(P=1.000) of patients. Conclusions: The study shows a high concordance of KRAS, NRAS, BRAF and PIK3CA gene mutations in plasma against mutation status in tumor tissue. In colorectal cancer, tumor tissue remains the best specimen for gene detection. However, patients from tumor tissue specimens cannot be obtained, especially those with advanced metastases, plasma can be used instead of tissue to detect the mutation status of KRAS, NRAS, BRAF and PIK3CA to guide targeted therapy.

Inhibition of MERTK Promotes Suppression of Tumor Growth in BRAF Mutant and BRAF Wild-Type Melanoma.

Molecularly-targeted agents have improved outcomes for a subset of patients with BRAF-mutated melanoma, but treatment of resistant and BRAF wild-type tumors remains a challenge. The MERTK receptor tyrosine kinase is aberrantly expressed in melanoma and can contribute to oncogenic phenotypes. Here we report the effect of treatment with a MERTK-selective small molecule inhibitor, UNC2025, in preclinical models of melanoma. In melanoma cell lines, treatment with UNC2025 potently inhibited phosphorylation of MERTK and downstream signaling, induced cell death, and decreased colony formation. In patient-derived melanoma xenograft models, treatment with UNC2025 blocked or significantly reduced tumor growth. Importantly, UNC2025 had similar biochemical and functional effects in both BRAF-mutated and BRAF wild-type models and irrespective of NRAS mutational status, implicating MERTK inhibition as a potential therapeutic strategy in tumors that are not amenable to BRAF-targeting and for which there are limited treatment options. In BRAF-mutated cell lines, combined treatment with UNC2025 and the BRAF inhibitor vemurafenib provided effective inhibition of oncogenic signaling through ERK, AKT, and STAT6, increased induction of cell death, and decreased colony-forming potential. Similarly, in NRAS-mutated cell lines, addition of UNC2025 to cobimetinib therapy increased cell death and decreased colony-forming potential. In a BRAF-mutated patient-derived xenograft, treatment with combined UNC2025 and vemurafenib was well-tolerated and significantly decreased tumor growth compared with vemurafenib alone. These data support the use of UNC2025 for treatment of melanoma, irrespective of BRAF or NRAS mutational status, and suggest a role for MERTK and targeted combination therapy in BRAF and NRAS-mutated melanoma.

Microfluidic enrichment, isolation and characterization of disseminated melanoma cells from lymph node samples.

For the first time in melanoma, novel therapies have recently shown efficacy in the adjuvant therapy setting, which makes companion diagnostics to guide treatment decisions a desideratum. Early spread of disseminated cancer cells (DCC) to sentinel lymph nodes (SLN) is indicative of poor prognosis in melanoma and early DCCs could therefore provide important information about the malignant seed. Here, we present a strategy for enrichment of DCCs from SLN suspensions using a microfluidic device (Parsortix™, Angle plc). This approach enables the detection and isolation of viable DCCs, followed by molecular analysis and identification of genetic changes. By optimizing the workflow, the established protocol allows a high recovery of DCC from melanoma patient-derived lymph node (LN) suspensions with harvest rates above 60%. We then assessed the integrity of the transcriptome and genome of individual, isolated DCCs. In LNs of melanoma patients, we detected the expression of melanoma-associated transcripts including MLANA (encoding for MelanA protein), analyzed the BRAF and NRAS mutational status and confirmed the malignant origin of isolated melanoma DCCs by comparative genomic hybridization. We demonstrate the feasibility of epitope-independent isolation of LN DCCs using Parsortix™ for subsequent molecular characterization of isolated single DCCs with ample application fields including the use for companion diagnostics or subsequent cellular studies in personalized medicine.

KRAS and TP53 mutations are correlated with lower survival rate in resected pancreatic ductal adenocarcinoma

Background: Factors responsible for long-term survival of patients with pancreatic ductal adenocarcinoma (PDAC) underwent surgical procedure are poorly understood. Aim of the present study was to clarify the clinical implication of the molecular status of the four genes (KRAS, TP53, p16 and SMAD4), and of other molecular markers, as IDH1 mutation gene, MSI and MGMT promoter methylation status. Methods: In this study, 30 PDAC were analyzed. Fifteen patients had a survival rate higher than 53 months from surgery (LS) and 15 patients died for disease before than 24 months from surgery (NLS). The samples were analyzed for KRAS, TP53, NRAS and BRAF mutational status using Next Generation Sequencing. Results: NLS group had a higher frequency of cases mutated for KRAS (86.7%) and TP53 (46.7) if compared to LS patients (60.0% p= 0.2148 and 33.3% p= 0.7104, respectively). Intriguingly, when we compared the survival of both “KRAS+TP53” mutated patients with that of “WT/WT” subjects we observed that the survival time of the second group was more than twice higher than the one of “double-mutated samples” (81.0 months vs 35.8 months, p=0.0825). Conclusion: Our data strongly support the fact that KRAS and TP53 mutations identify a subset of PCs with worst behaviour. patients with a KRAS/TP53 mutations had a survival rate less than half if compared with that of KRAS/TP53 wild-type subjects.These molecular markers could be analysed in preoperative material (e.g. EUS-FNA), allowing to provide prognostic information for tailored treatment.

KRAS and TP53 mutations are correlated with lower survival rate in resected pancreatic ductal adenocarcinoma

Background: Factors responsible for long-term survival of patients with pancreatic ductal adenocarcinoma (PDAC) underwent surgical procedure are poorly understood. Aim of the present study was to clarify the clinical implication of the molecular status of the four genes (KRAS, TP53, p16 and SMAD4), and of other molecular markers, as IDH1 mutation gene, MSI and MGMT promoter methylation status Methods: In this study, 30 PDAC were analyzed. Fifteen patients had a survival rate higher than 53 months from surgery (LS) and 15 patients died for disease before than 24 months from surgery (NLS). The samples were analyzed for KRAS, TP53, NRAS and BRAF mutational status using Next Generation Sequencing Results: NLS group had a higher frequency of cases mutated for KRAS (86.7%) and TP53 (46.7) if compared to LS patients (60.0% p= 0.2148 and 33.3% p= 0.7104, respectively). Intriguingly, when we compared the survival of both “KRAS+TP53” mutated patients with that of “WT/WT” subjects we observed that the survival time of the second group was more than twice higher than the one of “double-mutated samples” (81.0 months vs 35.8 months, p=0.0825) Conclusion: Our data strongly support the fact that KRAS and TP53 mutations identify a subset of PCs with worst behaviour. patients with a KRAS/TP53 mutations had a survival rate less than half if compared with that of KRAS/TP53 wild-type subjects. These molecular markers could be analysed in preoperative material (e.g. EUS-FNA), allowing to provide prognostic information for tailored treatment.

Establishment and characterization of melanoma patient-derived xenograft models for preclinical evaluation of novel therapeutics.

Patient-derived xenograft (PDX) models mostly retain the histological and genetic features of their donor tumors, which have been used for investigating various types of cancer. However, PDX models for melanoma, especially acral melanoma, are reported occasionally. We aimed to establish a large panel of melanoma PDX models representing the predominant Asian melanomas. Ninety-three fresh melanoma samples were implanted subcutaneously into nonobese diabetic/severe combined immunodeficiency mice. The histological and genetic characteristics were analyzed in both patient tumors and PDX models using immunohistochemistry, PCR amplification, and Sanger sequencing. Furthermore, the sensitivities of PDX models harboring distinct mutation profiles to binimetinib (a MEK inhibitor), vemubrafenib (a BRAF inhibitor), and imatinib (a KIT inhibitor) were also evaluated. Twenty-five PDX models were established successfully [25/93 (26.9%)] and passaged to maintain tumors in vivo. Clinical stage and origin of tumor sample were correlated with successful establishment rates (P=0.008 and <0.001, respectively). The histological (expression of NRAS, P16, and RB) and genetic (mutation status of NRAS, BRAF, and KIT) characteristics were stably maintained from patient tumors to PDX models. Targeted drugs could inhibit the tumor growth of PDX models harboring the corresponding target gene mutations. These PDX models constitute a pharmacological platform, enabling personalized development of therapeutic strategies for Asian melanomas.