Lise Barlebo Ahlborn

Splicing analysis of 14 BRCA1 missense variants classifies nine variants as pathogenic

Pathogenic germline mutations in the BRCA1 gene predispose carriers to early onset breast and ovarian cancer. Clinical genetic screening of BRCA1 often reveals variants with uncertain clinical significance, complicating patient and family management. Therefore, functional examinations are urgently needed to classify whether these uncertain variants are pathogenic or benign. In this study, we investigated 14 BRCA1 variants by in silico splicing analysis and mini-gene splicing assay. All 14 alterations were missense variants located within the BRCT domain of BRCA1 and had previously been examined by functional analysis at the protein level. Results from a validated mini-gene splicing assay indicated that nine BRCA1 variants resulted in splicing aberrations leading to truncated transcripts and thus can be considered pathogenic (c.4987A>T/p.Met1663Leu, c.4988T>A/p.Met1663Lys, c.5072C>T/p.Thr1691Ile, c.5074G>C/p.Asp1692His, c.5074G>A/p.Asp1692Asn, c.5074G>T/p.Asp1692Tyr, c.5332G>A/p.Asp1778Asn, c.5332G>T/p.Asp1778Tyr, and c.5408G>C/p.Gly1803Ala), whereas five BRCA1 variants had no effect on splicing (c.4985T>C/p.Phe1662Ser, c.5072C>A/p.Thr1691Lys, c.5153G>C/p.Trp1718Ser, c.5154G>T/p.Trp1718Cys, and c.5333A>G/p.Asp1778Gly). Eight of the variants having an effect on splicing (c.4987A>T/p.Met1663Leu, c.4988T>A/p.Met1663Lys, c.5074G>C/p.Asp1692His, c.5074G>A/p.Asp1692Asn, c.5074G>T/p.Asp1692Tyr, c.5332G>A/p.Asp1778Asn, c.5332G>T/p.Asp1778Tyr, and c.5408G>C/p.Gly1803Ala) were previously determined to have no or an uncertain effect on the protein level, whereas one variant (c.5072C>T/p.Thr1691Ile) were shown to have a strong effect on the protein level as well. In conclusion, our study emphasizes that in silico splicing prediction and mini-gene splicing analysis are important for the classification of BRCA1 missense variants located close to exon/intron boundaries.

Validation study of HPV DNA detection from stained FNA smears by polymerase chain reaction: Improving the diagnostic workup of patients with a tumor on the neck.

Human papillomavirus (HPV)–related oropharyngeal squamous cell carcinoma (OPSCC) often presents with cystic cervical metastasis and a small primary tumor localized in the palatine tonsils or base of the tongue, which is diagnostically challenging. Testing for HPV DNA in fine‐needle aspiration (FNA) smears from metastases may facilitate a targeted diagnostic workup for identifying the primary tumor. This study was designed to assess the ability to detect HPV DNA in FNA smears with polymerase chain reaction (PCR).

Identification of a breast cancer family double heterozygote for RAD51C and BRCA2 gene mutations

Next-generation sequencing has entered routine genetic testing of hereditary breast cancer. It has provided the opportunity to screen multiple genes simultaneously, and consequently has identified new complex genotypes. Here we report the first identification of a woman double heterozygote for mutations in the RAD51C and BRCA2 genes. The RAD51C missense mutation p.Arg258His has previously been identified in a homozygous state in a patient with Fanconi anemia. This mutation is known to affect the DNA repair function of the RAD51C protein. The BRCA2 p.Leu3216Leu synonymous mutation has not been described before and mini-gene splicing experiments revealed that the mutation results in skipping of exon 26 containing a part of the DNA-binding domain. We conclude that the woman has two potential disease-causing mutations and that predictive testing of family members should include both the RAD51C and BRCA2 mutation. This study illustrates the advantage of sequencing gene panels using next-generation sequencing in terms of genetic testing.

Next-Generation Sequencing–Based Detection of Germline Copy Number Variations in BRCA1/BRCA2: Validation of a One-Step Diagnostic Workflow

Genetic testing of BRCA1/2 includes screening for single nucleotide variants and small insertions/deletions and for larger copy number variations (CNVs), primarily by Sanger sequencing and multiplex ligation-dependent probe amplification (MLPA). With the advent of next-generation sequencing (NGS), it has become feasible to provide CNV information and sequence data using a single platform. We report the use of NGS gene panel sequencing on the Illumina MiSeq platform and JSI SeqPilot SeqNext software to call germline CNVs in BRCA1 and BRCA2. For validation 18 different BRCA1/BRCA2 CNVs previously identified by MLPA in 48 Danish breast and/or ovarian cancer families were analyzed. Moreover, 120 patient samples previously determined as negative for BRCA1/BRCA2 CNVs by MLPA were included in the analysis. Comparison of the NGS data with the data from MLPA revealed that the sensitivity was 100%, whereas the specificity was 95%. Taken together, this study validates a one-step bioinformatics work-flow to call germline BRCA1/2 CNVs using data obtained by NGS of a breast cancer gene panel. The work-flow represents a robust and easy-to-use method for full BRCA1/2 screening, which can be easily implemented in routine diagnostic testing and adapted to genes other than BRCA1/2.

Detection of copy number alterations in cell-free tumor DNA from plasma

Background Somatic copy number alterations (SCNAs) occurring in tumors can provide information about tumor classification, patients outcome or treatment targets. Liquid biopsies, incl. plasma samples containing circulating cell-free tumor DNA (ccfDNA) can be used to assess SCNAs for clinical purposes, however specify and reliability of methods have to be tested. Methods SNP microarrays (Affymetrix) were used to generate whole-genome copy number profiles from plasma ccfDNA (OncoScan) and paired tumor biopsies (CytoScan) from ten patients with metastatic cancers. Numerical, segmental and focal SCNAs were assessed using ASCAT/TuScan and SNP-FASST2. Results Aberrations in ccfDNA in 4 patients resembled numerical (76%) and segmental (80%) aberrations in tDNA. Three patients represented low correlation due to postponed sampling time, ccfDNA quality and possible treatment interference. Breakpoints of high-amplitude amplification were assessed with high accuracy and relative breakpoints difference of only 7% (0.02–37%). Similarly, biallelic losses were reliably detected. Array was 100% successful in detection of SCNAs on clinically relevant genes compared to SCNAs in tumor biopsies. Tracking of SCNAs changes during the treatment course of one patient also indicated that apoptosis/necrosis of non-cancerous cells presumably induced by treatment can influence ccfDNA composition and introduce false-negative findings into the analysis of liquid biopsies. Conclusions Genomic alterations detected in ccfDNA from liquid biopsies by comprehensive SNP array are reliable source for information for stratification of patients for targeted treatment. General significance Clinically relevant SCNAs can be detected in ccfDNA with high resolution and can therefore serve as an alternative to tumor biopsy in defining treatment targets.

Circulating tumor DNA as a marker of treatment response in BRAF V600E mutated non-melanoma solid tumors

Purpose We evaluated longitudinal tracking of BRAF V600E in circulating cell-free DNA (cfDNA) as a marker of treatment response to BRAF inhibitor (BRAFi) combination therapies in non-melanoma solid tumors included in the Copenhagen Prospective Personalized Oncology (CoPPO) program. Experimental design Patients with BRAF V600E-mutated tumors were treated with combination therapies including BRAFi. Quantification of mutant cfDNA from plasma was determined and correlated to clinical outcomes. Exome sequencing was performed to identify possible resistance mutations. Results Twenty-three patients had BRAF-mutated tumors out of 455 patients included in CoPPO and 17 started BRAFi combination (EGFRi/MEKi) therapy. Tumor responses were achieved in 8 out of 16 evaluable patients and the median overall- and progression-free survival (OS and PFS) was 15 and 4.8 months, respectively. Longitudinal measurements of BRAF V600E-mutant cfDNA indicated disease progression prior to radiological evaluation and a reduction in the mutant fraction of more than 50% after 4 and 12 weeks of therapy was associated with a significantly longer PFS (p=0.003 and p=0.029) and OS (p=0.029 and p=0.017). Furthermore, the baseline mutant fraction and total level of cfDNA positively correlated with tumor burden (p=0.026 and p=0.024). Finally, analysis of cfDNA at progression revealed novel mutations potentially affecting the MAPK pathway. Conclusion BRAFi combination therapies showed a response rate of 50% in BRAF V600E-mutated non-melanoma tumors. The fraction of BRAF-mutant cfDNA represent a sensitive indicator for clinical outcomes with plasma collected at week 4 and 12 as crucial time points for monitoring response and disease progression.

Concordance of Mutation Detection in Circulating Tumor DNA in Early Clinical Trials Using Different Blood Collection Protocols

BACKGROUND Small fragments of tumor DNA can be found in the circulation of cancer patients, providing a noninvasive access to tumor material (liquid biopsy). Analysis of circulating tumor DNA (ctDNA) has been used for diagnosis, treatment decisions, and detection of therapy resistance, including in patients with tumors inaccessible for biopsy, making ctDNA an important alternative source of tumor material. Immediate separation of plasma is widely used in standard isolation of cell-free DNA to ensure high quality plasma DNA. However, these procedures are labor intensive and logistically challenging in a clinical setting. Here we investigate the concordance between standard blood collection for molecular analysis using immediate separation of plasma, compared to the use of collection tubes allowing for delayed processing. METHODS In this study, we measured the fractional abundance of tumor specific mutations (BRAF p.V600E and PIK3CA p.H1047R) in ctDNA isolated from blood samples collected in either cell-stabilizing Cell-Free DNA BCT tubes (delayed processing within 72 hours) or standard K3EDTA tubes (immediate processing within 15 minutes). Twenty-five blood sample pairs (EDTA/BCT) were collected from patients with advanced solid cancers enrolled in early clinical trials. RESULTS Concordance in the fractional abundance of mutations in ctDNA isolated from blood collected in either K3EDTA or BCT tubes from patients with different solid cancers was observed. CONCLUSIONS This study indicates that BCT tubes are preferable for collection of circulating DNA in a clinical setting due to the favorable storage and shipping conditions.

Detection of HPV-DNA from May-Grunvald-Giemsa Stained Fine Needle Aspiration Specimens Using Polymerase Chain Reaction

Results: IPMC involved >5% of villi in 11 of 17 placentas (65%) from FD cases, but only 1 of 118 from live births (0.8%, p<0.0001). IPMC involved >10% of villi in 5 of 17 placentas (30%) from FD cases and none from live births (0%, p<0.0001). Clinical data for 11 of the 17 FD cases was available. IPMC in >5% of villi were seen in 3 of the 7 cases where fetus was delivered within 1 day, versus 4 of 4 cases where fetus was retained for >1 days after demise (p<.05). Frequency of IPMC in categories other than fetal demise are shown in table 1.

Dynamics of mutant BRAF V600E in free circulating DNA (fcDNA) of non-melanoma cancer patients (pts) in response to treatment with BRAF and MEK/EGFR inhibitors.

11531Background: Therapies targeting mutant BRAF V600E have changed practice in the treatment of metastatic melanoma and are currently tested in other malignancies. Treatment response can be monito...