The role of HER2 as a therapeutic biomarker in gynaecological malignancy: potential for use beyond uterine serous carcinoma

Human epidermal growth factor receptor 2 (HER2) is a prognostic biomarker and therapeutic target in carcinomas of the breast, stomach and colon. In 2018, clinical trial data confirmed the prognostic and predictive role of HER2 in uterine serous carcinoma, with a demonstrated survival benefit from combined chemotherapy and anti-HER2 targeted therapy in patients with advanced or recurrent disease. Approximately one-third of uterine serous carcinomas demonstrate HER2 protein overexpression and/or gene amplification and HER2 immunohistochemistry, supplemented by in situ hybridisation in equivocal cases, is fast becoming a reflex ancillary test at time of diagnosis. The potential role of HER2 in gynaecological tumours other than uterine serous carcinoma is yet to be firmly established. With the advent of personalised medicine, routine tumour sequencing and pursuit of targeted therapies, this is a field currently under active investigation. Emerging data suggest triaging endometrial carcinomas for HER2 analysis based on molecular classification may be superior to histotype-based testing, with copy-number high/p53 mutant tumours enriched for HER2 overexpression or amplification. Accordingly, many carcinosarcomas and a subset of clear cell and high-grade endometrioid carcinomas may be eligible for HER2 targeted therapy, although any clinical benefit in this context is currently undefined. For ovarian carcinomas, combined data support the role of HER2 as a prognostic biomarker, however its use as a therapeutic target is yet to be elucidated through clinical trials. In the cervix, reported rates of HER2 overexpression vary and are generally low, and currently there is insufficient evidence to justify routine HER2 testing in this context. Limited data suggest HER2 holds promise as a prognostic and predictive biomarker in vulvar Paget disease. Future clinical trials, with pathologist input to develop and refine site-specific scoring criteria, are required to establish what role HER2 might play more broadly in gynaecological cancer care.

Diagnostic accuracy of 1p/19q codeletion tests in oligodendroglioma: A comprehensive meta-analysis based on a Cochrane systematic review

Codeletion of chromosomal arms 1p and 19q, in conjunction with a mutation in the isocitrate dehydrogenase 1 or 2 gene, is the molecular diagnostic criterion for oligodendroglioma, IDH mutant and 1p/19q codeleted. 1p/19q codeletion is a diagnostic marker and allows prognostication and prediction of the best drug response within IDH-mutant tumours. We performed a Cochrane review and simple economic analysis to establish the most sensitive, specific and cost-effective techniques for determining 1p/19q codeletion status. Fluorescent in situ hybridisation (FISH) and polymerase chain reaction (PCR)-based loss of heterozygosity (LOH) test methods were considered as reference standard. Most techniques (FISH, chromogenic in situ hybridisation [CISH], PCR, real-time PCR, multiplex ligation-dependent probe amplification [MLPA], single nucleotide polymorphism [SNP] array, comparative genomic hybridisation [CGH], array CGH, next-generation sequencing [NGS], mass spectrometry and NanoString) showed good sensitivity (few false negatives) for detection of 1p/19q codeletions in glioma, irrespective of whether FISH or PCR-based LOH was used as the reference standard. Both NGS and SNP array had a high specificity (fewer false positives) for 1p/19q codeletion when considered against FISH as the reference standard. Our findings suggest that G banding is not a suitable test for 1p/19q analysis. Within these limits, considering cost per diagnosis and using FISH as a reference, MLPA was marginally more cost-effective than other tests, although these economic analyses were limited by the range of available parameters, time horizon and data from multiple healthcare organisations.

Detection of NTRK fusions in glioblastoma: fluorescent in situ hybridisation is more useful than pan-TRK immunohistochemistry as a screening tool prior to RNA sequencing

Glioblastomas are frequent malignant brain tumours with a very poor prognosis and a need for new and efficient therapeutic strategies. With the approval of anti-TRK targeted therapies to treat patients with advanced NTRK-rearranged cancers, independent of the type of cancer, potential new treatment opportunities are available for the 0.5-5% of patients with NTRK-rearranged glioblastomas. Identification of these rare NTRK-rearranged glioblastomas requires efficient diagnostic tools and strategies which are evaluated in this study. We compared the results of NTRK1, NTRK2 and NTRK3 fluorescent in situ hybridisation (FISH) assays to those of pan-TRK immunohistochemistry (IHC) using two EPR17341 and A7H6R clones in a set of 196 patients with glioblastomas. Cases with at least 15% of positive nuclei using FISH analyses were further analysed using RNA sequencing. Above the 15% threshold, seven positive glioblastomas (3.57%) were identified by FISH assays (4 NTRK1, 3 NTRK2, no NTRK3). NTRK rearrangements were confirmed by RNA sequencing analyses in four cases [1 LMNA-NTRK1, 1 PRKAR2A-NTRK2, 1 SPECC1L-NTRK2 and 1 NACC2-NTRK2 fusions, i.e., 4/196 (2%) of NTRK-rearranged tumours in our series] but no rearrangement was detected in three samples with less than 30% of positive tumour nuclei as determined by NTRK1 FISH. Pan-TRK immunostaining showed major discrepancies when using either the EPR17341 or the A7H6R clones for the following criteria: main intensity, H-Score based scoring and homogeneity/heterogeneity of staining (Kappa values <0.2). This led to defining adequate criteria to identify NTRK-rearranged gliomas exhibiting strong and diffuse immunostaining contrasting to the variable and heterogeneous staining in non-NTRK-rearranged gliomas (p<0.0001). As assessing NTRK rearrangements has become crucial for glioma therapy, FISH seems to be a valuable tool to maximise access to TRK testing in patients with glioblastomas. In contrast to other cancers, pan-TRK IHC appears of limited interest in this field because there is no 'on/off' IHC positivity criterion to distinguish between NTRK-rearranged and non-NTRK-rearranged gliomas. RNA sequencing analyses are necessary in FISH positive cases with less than 30% positive nuclei, to avoid false positivity when scoring is close to the detection threshold.

Human epidermal growth factor receptor 2 (HER2) gene amplification in non-muscle invasive urothelial bladder cancers: Identification of patients for targeted therapy

Objectives

To evaluate human epidermal growth factor receptor 2 (HER2) protein overexpression by immunohistochemistry (IHC) and gene amplification by fluorescent in situ hybridisation (FISH) in urothelial non-muscle-invasive bladder carcinoma (NMIBC), as HER2 is a potential therapeutic target in muscle-invasive bladder carcinoma (MIBC) and HER2 expression and gene amplification in low/high-grade and pTa/pT1 NMIBC is not clear.

Patients and methods

The study included 93 bladder cancers; 25 MIBC and 68 NMIBC (37 low- and 31 high-grade). All HER2 positive (3+) and equivocal (2+) cases were subjected to FISH using a HER2/CEN 17 dual-colour probe kit. IHC and FISH were scored as per the American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) 2013 Guidelines for breast cancers. Based on the number of signals/nuclei, amplification was categorised as low (≥6–10) and high-level (≥10).

Results

HER2 2–3+ expression was seen in 29% of NMIBCs (10.8% low- and 51.6% high-grade). HER2 3+ expression was seen in high-grade NMIBC (nine of 31; 29%) and MIBC (nine of 25; 36%). In all, 87% of high-grade NMIBCs were lamina invasive (pT1). Gene amplification was found in 45% (eight of 18) of 3+ tumours. None of the HER2 2+ tumours showed gene amplification. IHC and FISH results were in closest agreement when ≥50% of tumour cells showed 3+ expressions. High-level amplification correlated with increased gene expression on reverse transcriptase-polymerase chain reaction. On multivariate analysis, lower  stage, grade, and HER2 expression significantly correlated with progression-free survival. HER2 3+ expression in NMIBC correlated significantly with time to recurrence and progression.

Conclusion

Our present results show that HER2 FISH should not be performed for HER2 2 + and low-grade NMIBC. This contrasts with breast cancers where it is recommended for equivocal 2+ tumours. About 50% of HER2 3+ MIBC and high-grade NMIBC show HER2 gene amplification and can be potential candidates for HER2-targeted therapy.

Abbreviations

ASCO/CAP: American Society of Clinical Oncology/College of American Pathologists; DAB: 3,3ʹ-diaminobenzidine; FISH: fluorescent in situ hybridisation; HER2: human epidermal growth factor receptor 2; IHC: immunohistochemistry;(N)MIBC: (non-) muscle-invasive bladder carcinoma; MPUC: micropapillary variant of urothelial bladder cancer; PFS: progression-free survival; TURBT: transurethral resection of bladder tumour

Age-related differences revealed in Australian fur seal Arctocephalus pusillus doriferus gut microbiota

The gut microbiota of Australian fur seals (Arctocephalus pusillus doriferus) was examined at different age classes using fluorescent in situ hybridisation (FISH) and 16S rRNA gene pyrosequencing. The FISH results indicated that in the fur seal groups, the predominant phyla are Firmicutes (22.14-67.33%) followed by Bacteroidetes (3.11-15.45%) and then Actinobacteria (1.4-5.9%) consistent with other mammals. Phylum Proteobacteria had an initial abundance of 1.8% in the 2-month-old pups, but < 1% of bacterial numbers for the other fur seal age groups. Significant differences did occur in the abundance of Clostridia, Lactobacilli and Bifidobacteria between 2 months pups and 9 months pups and adult fur seals. Results from the 16S rRNA gene pyrosequencing supported the FISH data and identified significant differences in the composition of Firmicutes, Bacteroidetes, Actinobacteria, Proteobacteria, Verrucomicrobia and Fusobacteria at all ages. Class Clostridia in phylum Firmicutes dominates the microbiota of the 2 months and 9 months seal pups, whilst class Bacilli dominates the 6 months pups. In addition, a high level of dissimilarity was observed between all age classes. This study provides novel insight into the gut microbiota of Australian fur seals at different age classes.

Hepatitis C virus replicates in peripheral blood mononuclear cells of patients with occult hepatitis C virus infection

BACKGROUND

Occult hepatitis C virus (HCV) infection is characterised by the presence of HCV-RNA in the liver in the absence of anti-HCV, and serum viral RNA. Up to 70% of these patients also have HCV-RNA in peripheral blood mononuclear cells (PBMC) but it is not known if HCV is replicating in these cells.

AIM

We studied possible HCV replication in PBMC of 18 patients with an occult HCV infection who were selected on the basis of HCV-RNA positivity in PBMC.

METHODS

Detection of HCV-RNA positive and negative strands in PBMC was done by strand specific reverse transcriptase-polymerase chain reaction (RT-PCR) and by in situ hybridisation.

RESULTS

The presence of HCV-RNA positive strand in PBMC was confirmed in all patients by strand specific RT-PCR and by in situ hybridisation. Mean percentage of PBMC which had the HCV-RNA positive strand was 3.3% (95% confidence interval (CI) 2.1-4.4) The HCV-RNA negative strand was found in the PBMC of 11/18 (61%) patients by strand specific RT-PCR and confirmed by in situ hybridisation, and the percentage of PBMC harbouring the HCV-RNA negative strand was 3.1% (95% CI 0.8-5.5). There was a significant correlation (p = 0.001, r = 0.84) between the percentage of PBMC with the HCV-RNA positive strand and that of PBMC with the HCV-RNA negative strand.

CONCLUSION

HCV replicates in the PBMC of patients with occult HCV infection and thus, although these patients do not have serum HCV-RNA, they could be potentially infectious.

Demystified... Molecular pathology in oncology

In the past 10 years, molecular biology has found major applications in pathology, particularly in oncology. This has been a field of enormous expansion, where pure science has found a place in clinical practice and is now of everyday use in any academic unit. This demystified review will discuss the techniques used in molecular pathology and then provide examples of how these can be used in oncology.