Report of a case of RAVEN, hair heterochromia and autism in the setting of FGFR2 mutation

A newborn presented with extensive rounded and velvety epidermal nevus (RAVEN) with a genetic study of the cutaneous lesions revealing a heterozygous mutation in FGFR2 (p.Cys382Arg). By 2 years of age, the patient developed hair heterochromia and autism spectrum disorder. Although RAVEN was initially associated with fibroblast growth factor 3 (FGFR3) mutations, three cases of RAVEN have been identified with mutations in FGFR2 (p.Ser252Trp) and one case of linear keratinocytic epidermal nevi has been identified with the same mutation as the mutation identified in our patient. This strongly supports the pathogenic role of these mutations.

dPCR application in liquid biopsies: divide and conquer

Introduction: Precision medicine is already a reality in oncology, since biomarker-driven therapies have clearly improved patient survival. Furthermore, a new, minimally invasive strategy termed 'liquid biopsy' (LB) has revolutionized the field by allowing comprehensive cancer genomic profiling through the analysis of circulating tumor DNA (ctDNA). However, its detection requires extremely sensitive and efficient technologies. A powerful molecular tool based on the principle of 'divide and conquer' has emerged to solve this problem. Thus, digital PCR (dPCR) allows absolute and accurate quantification of target molecules.Areas covered: In this review we will discuss the fundamentals of dPCR and the most common approaches used for partition of samples and quantification. The advantages and limitations of dPCR will be mentioned in the context of LB in oncology.Expert opinion: In our opinion, dPCR has proven to be one of the most sensitive methods available for LB analysis, albeit some aspects such as its capacity of multiplexing and protocol standardization still require further improvements. Furthermore, the increasing sensitivities and lower costs of next generation sequencing (NGS) methods position dPCR as a confirmatory and complementary technique for NGS results which will likely prove to be very useful for treatment monitoring and assessing minimal residual disease.

Prognostic Impact of let-7e MicroRNA and Its Target Genes in Localized High-Risk Intestinal GIST: A Spanish Group for Research on Sarcoma (GEIS) Study

MicroRNAs (miRNAs) are small non-coding RNAs that negatively regulate gene expression at the post-transcriptional level, and they have been described as being associated with tumor prognosis. Here, miRNA profiling was planned to explore new molecular prognostic biomarkers in localized intestinal high-risk GIST. Paraffin tumor blocks of 14 and 86 patients were used in the discovery and expansion sets, respectively. GeneChip miRNA v3.0 was employed to identify the miRNAs differentially expressed between relapsed and non-relapsed patient samples, which were validated in the expansion set, by qRT-PCR. RT2 Profiler PCR Array was used for the screening of let-7e targets. Expression levels were correlated with relapse-free survival and overall survival. In the discovery set, 39 miRNAs were significantly deregulated, let-7e and miR-550 being the most underexpressed and overexpressed miRNAs in the relapsed group, respectively. In the expansion set, the underexpression of let-7e or the overexpression of 4 of its target genes (ACVR1B, CASP3, COL3A1, and COL5A2) were statistically associated with worse relapse-free survival. The expression of let-7e and 4 of its target genes are potential prognostic biomarkers in high-risk localized intestinal GIST. The expression of these genes is a potential molecular tool useful for a more accurate prognosis in this subset of GIST patients.

Nilotinib as Coadjuvant Treatment with Doxorubicin in Patients with Sarcomas: A Phase I Trial of the Spanish Group for Research on Sarcoma

Purpose: Nilotinib plus doxorubicin showed to be synergistic regarding apoptosis in several sarcoma cell lines. A phase I/II trial was thus designed to explore the feasibility of nilotinib as coadjuvant of doxorubicin by inhibiting MRP-1/P-gp efflux activity. The phase I part of the study is presented here.Patients and Methods: Nilotinib 400 mg/12 hours was administered in fixed dose from day 1 to 6, and doxorubicin on day 5 of each cycle. Three dose escalation levels for doxorubicin at 60, 65, and 75 mg/m² were planned. Cycles were repeated every 3 weeks for a total of 4 cycles. Eligible subtypes were retroperitoneal liposarcoma, leiomyosarcoma, and unresectable/metastatic high-grade chondrosarcoma.Results: Thirteen patients were enrolled: 7 chondrosarcoma, 4 liposarcoma, and 2 leiomyosarcoma. In 46 cycles administered, the most relevant grade 3/4 adverse effects per patient were neutropenia 54%, febrile neutropenia 15%, and asthenia 8%. No cardiac toxicity was observed. Only one dose-limiting toxicity (febrile neutropenia) was reported in the third dose level. With regard to efficacy, 1 partial response (1 liposarcoma), 9 stable diseases (5 chondrosarcoma, 2 liposarcoma, 1 leiomyosarcoma), and 3 progressive diseases (2 chondrosarcoma and 1 leiomyosarcoma) were present. ABCB1 and ABCC1 RNA expression levels decreased by 58.47-fold and 1.47-fold, respectively, on day 5 of the cycle.Conclusions: Combination of MRP-1/P-gp inhibitor, nilotinib, as coadjuvant with doxorubicin is feasible; it appears not to add substantial toxicity compared with doxorubicin alone. Pharmacodynamic study supports this concept. The recommended dose for the phase II part for doxorubicin was 75 mg/m² Clin Cancer Res; 24(21); 5239-49. ©2018 AACR.

Wnt signaling somatic alterations in apc-associated fap adenomas

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Background: APC mutations are believed to constitutively activate the wnt pathway in colorectal tumors. Our goal was to comprehensively characterize Wnt signaling components in a set of APC-associated FAP tumors both at the DNA and RNA levels. Methods: Sixty adenomas from FAP cases harboring pathogenic APC mutations were included (10 adenomas and 1 normal mucosa per case). Somatic APC and KRAS alterations, β-catenin immunostaining and qRT-PCR of APC, MYC, AXIN2 and SFRP1 were analyzed. aCGH was also assessed in 26 FAP adenomas and 24 additional paired normal-adenoma-carcinoma samples. Results: A second APC alteration was present in 30 (50%) of adenomas (26 LOH and 4 point mutations). LOH was only occasionally associated with loss of genetic material. In 3 of 6 cases APC mRNA was overexpressed in macroscopically normal mucosa. In these cases diminished APC levels mRNA were observed in 11 of 30 adenomas analyzed.. In the remaining 3 cases APC mRNA was already underexpressed in normal mucosa with only 3 of 30 adenomas showing further underexpression. In FAP normal mucosae MYC was overexpressed (logratio range: 3.37–5.66). All adenomas showed further MYC (logratio range: 1.78–2.92) and AXIN2 overexpression (logratio range: 1.62–4.65), corregulating with APC mRNA levels (r=0.31 for MYC; r=0.59 for AXIN2). β-catenin nuclear immunostaining was detected in 80% of adenomas correlating with MYC mRNA levels. SFRP1 was underexpressed in all tumors (logratio range= -3.06–27). While copy number changes were rare in adenomas (median number :2.5; range 0–5). DNA changes were more often detected in areas containing wnt genes when FAP and sporadic tumors were jointly analyzed (p=0.02). Conclusions: Wnt pathway is altered, at the DNA and/or RNA level, in all APC mutant FAP tumors. MYC overexpression is a universal event that correlates with APC and AXIN2 expression levels as well as bcatenin nuclear accumulation.

No significant financial relationships to disclose.

APC inactivation associates with abnormal mitosis completion and concomitant BUB1B/MAD2L1 up-regulation

BACKGROUND & AIMS

Chromosomal instability, a hallmark of most colorectal cancers, has been related to altered chromosome segregation and the consequent deficit in genetic integrity. A role for the tumor suppressor gene APC has been proposed in colorectal cancer that leads to compromised chromosome segregation even though the molecular mechanism is not yet understood. Here, we tackled the genetic basis for the contribution of APC to chromosomal instability in familial adenomatous polyposis and sporadic colorectal cancer.

METHODS

We have used video-microscopy of primary cultures and molecular genetic methods to address these issues in human samples and in genetically defined mouse models that either recapitulate the familial adenomatous polyposis syndrome (Apc(1638N)), or develop tumors in the absence of APC mutations (pvillin-KRASV12G).

RESULTS

Mutations in APC were associated with an increased incidence in cell cycle defects during the completion of cytokinesis. Transcriptome analysis performed on mouse models indicated a significant up-regulation of genes that regulate accurate mitosis. Notably, we identified up-regulated expression of BUB1B and MAD2L1, 2 genes that are involved in the mitotic checkpoint, but have so far not been implicated in chromosomal instability induced by APC loss of function. In vitro modulation of APC expression suggested a causal association for this upregulation, which was consistently found in sporadic and familial adenomatous polyposis lesions, as an early event in colorectal tumorigenesis.

CONCLUSIONS

In addition to the known function of APC during correct spindle assembly and positioning, we propose a concomitant involvement of APC in the surveillance mechanism of accurate mitosis.