Biomarkers and biomarker validation: a pathologist's guide to getting it right.

Biomarkers are central to the delivery of personalised/precision medicine and are increasingly used across all areas of medicine to improve diagnostic accuracy, determine prognosis and predict response to treatment. Biomarkers can be used to develop assays that are then further developed into diagnostic tests, or in vitro diagnostic devices, which require an exhaustive validation and approval process. Pathologists play a critical role in the ordering and interpretation of biomarker assays. However, the evolution of a new biomarker from discovery to clinical implementation is complex, subject to various levels of scientific, clinical and regulatory scrutiny, with an approval process that varies significantly between jurisdictions. Therefore, it is important that pathologists have a solid understanding of how biomarkers are developed, the process of biomarker validation, how new biomarkers are approved for clinical use and the potential issues around implementation of biomarker testing that may lead to inaccurate results. This paper aims to provide an overview of the process of biomarker development, approval and validation, and practical tips for anatomical pathologists involved in the testing of biomarkers in routine practice.

Prognostic Significance of Incipient Ulceration in Primary Cutaneous Melanoma.

Importance: Ulceration represents a key feature in cutaneous melanoma, contributing to staging according to the current American Joint Committee on Cancer (AJCC) system. However, cases with incipient ulceration do not quite fulfill the AJCC definition of ulceration and are consequently classified as nonulcerated, presenting interpretive difficulty for pathologists. The prognostic implication of incipient ulceration is uncertain. Objective: To evaluate the prognostic significance of incipient ulceration in cutaneous melanoma. Design, Setting, and Participants: This case-control study consisted of resected primary cutaneous melanomas diagnosed between 2005 and 2015, identified from the Melanoma Institute Australia research database and with slides available for review at Royal Prince Alfred Hospital. Slides were reviewed by pathologists experienced in the diagnosis of melanocytic lesions to identify cases (incipient ulceration) and controls (ulcerated or nonulcerated). Incipient ulceration cases were matched at a 1:2 ratio with nonulcerated and ulcerated controls, respectively. Study analysis was conducted from March to June 2023. Main Outcomes: Clinicopathological factors and clinical outcomes: overall survival (OS), melanoma-specific survival (MSS), and recurrence-free survival (RFS) were compared between cases and controls. Results: Of 2284 patients with melanoma identified, 340 patients (median [IQR] age, 69 [24-94] years; 136 [68%] men; median follow-up, 7.2 years) met the criteria. The matched cohort consisted of 40 cases of incipiently ulcerated melanoma matched 1:2 with 80 nonulcerated controls, and 80 ulcerated controls. The median (IQR) Breslow thickness differed significantly between cases and controls; 2.8 (1.7-4.1) mm for incipient cases compared with 1.0 (0.6-2.1) mm and 5.3 (3.5-8.0) mm for nonulcerated and ulcerated melanomas, respectively. Median (IQR) tumor mitotic rate was 5.0 (3.0-9.0) per mm2 in incipiently ulcerated cases compared with 1 (0-3.0) per mm2 in nonulcerated controls and 9 (5.0-14.0) per mm2 in ulcerated controls. Based on the matched cohorts, patients with nonulcerated tumors had significantly better OS (hazard ratio [HR], 0.49; 95% CI, 0.27-0.88; P = .02) and RFS (HR, 0.37; 95% CI, 0.22-0.64; P < .001) than patients with incipient ulceration. The RFS was significantly worse in ulcerated tumors compared with incipiently ulcerated cases (HR, 1.67; 95% CI, 1.07-2.60; P = .03). After adjusting for pathological factors, no statistically significant differences in clinical outcomes were observed between cases and either control group. Conclusions and Relevance: The findings of this case-control study indicate that incipient ulceration in a primary melanoma represents an adverse prognostic feature that should be noted by pathologists in their reports and considered in future guidelines.

Lag-3 expression and clinical outcomes in metastatic melanoma patients treated with combination anti-lag-3 + anti-PD-1-based immunotherapies.

Lymphocyte-activation gene-3 (LAG-3), an immune checkpoint receptor, negatively regulates T-cell function and facilitates immune escape of tumors. Dual inhibition of LAG-3 and programmed cell death receptor-1 (PD-1) significantly improved progression-free survival (PFS) in metastatic melanoma patients compared to anti-PD-1 therapy alone. Investigating the utility of LAG-3 expression as a biomarker of response to anti-LAG-3 + anti-PD-1 immunotherapy is of great clinical relevance. This study sought to evaluate the association between baseline LAG-3 expression and clinical outcomes following anti-LAG-3 and anti-PD-1-based immunotherapy in metastatic melanoma. LAG-3 immunohistochemistry (clone D2G4O) was performed on pre-treatment formalin-fixed, paraffin-embedded metastatic melanoma specimens from 53 patients treated with combination anti-LAG-3 + anti-PD-1-based therapies. Eleven patients had received prior anti-PD-1-based treatment. Patients were categorized as responders (complete/partial response; n = 36) or non-responders (stable/progressive disease; n = 17) based on the Response Evaluation Criteria in Solid Tumours (RECIST). Tumor-infiltrating lymphocytes (TILs) were scored on hematoxylin and eosin-stained sections. LAG-3 expression was observed in 81% of patients, with staining in TILs and dendritic cells. Responders displayed significantly higher proportions of LAG-3+ cells compared to non-responders (P = .0210). LAG-3 expression positively correlated with TIL score (P < .01). There were no significant differences in LAG-3 expression between different sites of metastases (P > .05). Patients with ≥ 1% LAG-3+ cells in their tumors had significantly longer PFS compared to patients with < 1% LAG-3 expression (P = .0037). No significant difference was observed in overall survival between the two groups (P = .1417). Therefore, the assessment of LAG-3 expression via IHC warrants further evaluation to determine its role as a predictive marker of response and survival in metastatic melanoma.

Dissecting a diagnostic enigma: Hypertension in a young patient from an organ of Zuckerkandl paraganglioma.

Hypertension in young patients can mask rare conditions like paragangliomas, especially in the absence of conventional symptoms. A comprehensive diagnostic evaluation and multidisciplinary approach are crucial for optimal management and outcomes.

Melanomas in children and adolescents: Clinicopathologic features and survival outcomes.

BACKGROUND: Melanomas in the first 2 decades of life are uncommon and poorly understood. OBJECTIVE: To assess clinicopathologic features and survival of children (≤11 years) and adolescents (12-19 years) diagnosed with melanoma. METHODS: A pooled cohort of 514 patients was analyzed (397 Dutch, 117 Australian; 62 children, 452 adolescents). Pathology reports were reevaluated to determine melanoma subtypes. Multivariable Cox models were generated for recurrence-free survival (RFS) and overall survival (OS). RESULTS: Melanoma subtypes were conventional melanoma (superficial spreading, nodular, desmoplastic, and acral lentiginous), spitzoid melanoma, and melanoma associated with a congenital nevus in 428, 78, and 8 patients, respectively. Ten-year RFS was 91.5% (95% confidence interval [CI], 82.4%-100%) in children and 86.4% (95% CI, 82.7%-90.3%) in adolescents (P = .32). Ten-year OS was 100% in children and 92.7% (95% CI, 89.8%-95.8%) in adolescents (P = .09). On multivariable analysis possible only for the adolescent cohort due to the small number of children, ulceration status, and anatomic site were associated with RFS and OS, whereas age, sex, mitotic index, sentinel node status and melanoma subtype were not. Breslow thickness >4 mm was associated with worse RFS. LIMITATIONS: Retrospective study. CONCLUSIONS: Survival rates for children and adolescents with melanomas were high. Ulceration, head or neck location and Breslow thickness >4 mm predicted worse survival in adolescents.

Rapid Development of Syringocystadenocarcinoma Papilliferum in an Immunosuppressed Liver Transplant Recipient.

Syringocystadenocarcinoma papilliferum (SCACP) is a rare cutaneous adnexal neoplasm. To the best of our knowledge, fewer than 50 cases have been described in the literature. We describe the first reported case of an SCACP in an immunocompromised patient. We report the development of an SCACP over 3 months in a 77-year-old organ transplant recipient undergoing regular dermatological follow-up. The lesion was excised with clear margins with Mohs micrographic surgery. This lesion's rapid development and small size contrasts with the predominantly slow-growing, larger lesions described in immunocompetent patients. Lastly, this case further highlights the importance of close dermatological follow-up of immunosuppressed patients.

Elevated non-coding promoter mutations are associated with malignant transformation of melanocytic naevi to melanoma.

Evolution from a benign naevus to a melanoma results principally from the stepwise accumulation of mutations. We used a custom next generation sequencing (NGS) panel targeting specific melanoma associated genes to analyse and compare differences between melanomas and their precursor naevi in coding and non-coding mutations and copy number aberrations, with a view to implementing this technique as an ancillary test to assist in the interpretation of difficult to diagnose melanocytic tumours. Fifteen cases of cutaneous melanoma with an adjacent morphologically benign (presumed precursor) naevus were selected. A custom NGS panel was used to sequence 54 melanoma associated genes in both the melanoma and the associated naevus for each case. In three cases, two morphologically distinct regions of the melanoma were sequenced. The adjacent (non-lesional) skin was also tested in nine cases. One case was excluded following molecular testing and clinicopathological reclassification as an epidermotropic melanoma metastasis. Twelve of the 14 tumours showed either BRAF or NRAS driver mutations. The melanomas harboured significantly more mutations than the adjacent naevi, particularly in non-coding promoter regions (p=0.002). There were significantly more non-coding promotor mutations in NRAS-mutant melanomas than BRAF-mutant melanomas (p=0.004). Mutations in TERT promoter regions were found preferentially in melanomas. Oncogenic events found exclusively in melanomas included PTEN loss in two BRAF-mutant melanomas and RAC1 P29S hyperactivating mutations in two NRAS-mutant melanomas. Higher numbers of mutations were present in melanomas compared to their precursor naevi. These findings support the further evaluation of this melanoma custom NGS panel as an ancillary test for interpreting difficult borderline melanocytic lesions.

H2A.B is a cancer/testis factor involved in the activation of ribosome biogenesis in Hodgkin lymphoma.

Testis-specific regulators of chromatin function are commonly ectopically expressed in human cancers, but their roles are poorly understood. Examination of 81 primary Hodgkin lymphoma (HL) samples showed that the ectopic expression of the eutherian testis-specific histone variant H2A.B is an inherent feature of HL. In experiments using two HL cell lines derived from different subtypes of HL, H2A.B knockdown inhibited cell proliferation. H2A.B was enriched in both nucleoli of these HL cell lines and primary HL samples. We found that H2A.B enhanced ribosomal DNA (rDNA) transcription, was enriched at the rDNA promoter and transcribed regions, and interacted with RNA Pol I. Depletion of H2A.B caused the loss of RNA Pol I from rDNA chromatin. Remarkably, H2A.B was also required for high levels of ribosomal protein gene expression being located at the transcriptional start site and within the gene body. H2A.B knockdown reduced gene body chromatin accessibility of active RNA Pol II genes concurrent with a decrease in transcription. Taken together, our data show that in HL H2A.B has acquired a new function, the ability to increase ribosome biogenesis.

Updates in the molecular pathology of non-small cell lung cancer.

An understanding of the molecular pathology of non-small cell lung cancer (NSCLC) is important for pathologists as molecular characterization is now required for treatment decisions in advanced stage disease. While assessment for EGFR mutations, ALK and ROS1 fusions, and in some countries BRAF mutations, is now standard practice, other oncogenic mutations are also emerging that may impact routine clinical practice including alterations involving KRAS, NTRK, RET, MET and HER2. In addition, molecular pathology alterations of NSCLC are associated with responses to immune checkpoint therapy and are being increasingly investigated. Finally, specific molecular pathological alterations define some rarer subtypes of NSCLC such as salivary gland tumours, NUT carcinoma and SMARCA4-deficient undifferentiated tumour, and an understanding of the molecular pathology is important for their accurate diagnosis. In this review, the molecular pathology of NSCLC is discussed with a focus on clinically relevant molecular alterations.

Programmed death ligand-1 (PD-L1) as a predictive marker for immunotherapy in solid tumours: a guide to immunohistochemistry implementation and interpretation.

Immunotherapy with checkpoint inhibitors is well established as an effective treatment for non-small cell lung cancer and melanoma. The list of approved indications for treatment with PD-1/PD-L1 checkpoint inhibitors is growing rapidly as clinical trials continue to show their efficacy in patients with a wide range of solid tumours. Clinical trials have used a variety of PD-L1 immunohistochemical assays to evaluate PD-L1 expression on tumour cells, immune cells or both as a potential biomarker to predict response to immunotherapy. Requests to pathologists for PD-L1 testing to guide choice of therapy are rapidly becoming commonplace. Thus, pathologists need to be aware of the different PD-L1 assays, methods of evaluation in different tumour types and the impact of the results on therapeutic decisions. This review discusses the key practical issues relating to the implementation of PD-L1 testing for solid tumours in a pathology laboratory, including evidence for PD-L1 testing, different assay types, the potential interchangeability of PD-L1 antibody clones and staining platforms, scoring criteria for PD-L1, validation, quality assurance, and pitfalls in PD-L1 assessment. This review also explores PD-L1 IHC in solid tumours including non-small cell lung carcinoma, head and neck carcinoma, triple negative breast carcinoma, melanoma, renal cell carcinoma, urothelial carcinoma, gastric and gastroesophageal carcinoma, colorectal carcinoma, hepatocellular carcinoma, and endometrial carcinoma. The review aims to provide pathologists with a practical guide to the implementation and interpretation of PD-L1 testing by immunohistochemistry.

A case of an asymptomatic sacrococcygeal teratoma diagnosed in adulthood.

Sacrococcygeal teratomas are rare congenital tumours that are even more uncommon when present in adulthood. They are derived from residual stem cells in the presacral space that differentiate into clusters of somatic cell. We present the diagnosis, management and post-operative follow-up in a 37-year-old gentleman referred to our department with an incidental finding of a lobulated presacral cystic mass on computed tomography imaging. Magnetic resonance imaging and fluorodeoxyglucose (FDG)-positron emission tomography (PET) scans were performed to further characterize the lesion. The decision was then made for surgical excision and the specimen along with the coccyx was retrieved en-bloc via a trans-sacral surgical approach. Histopathology of the mass uncovered the presence of squamous, respiratory and prostatic epithelium consistent with the diagnosis of a sacrococcygeal teratoma.

Human papilloma virus related squamous cell carcinomas of the head and neck: diagnosis, clinical implications and detection of HPV.

High-risk human papillomavirus (HPV) positive squamous cell carcinoma (SCC) of the head and neck is reported most commonly in the oropharynx but can also uncommonly be found in other sites such as the anterior oral cavity and sinonasal tract. While HPV positive oropharyngeal squamous cell carcinoma (HPV-OPSCC) has been shown to have a more favourable prognosis than conventional smoking- and alcohol-related anterior oral cavity squamous cell carcinoma (OSCC), HPV positive SCC arising elsewhere in the head and neck region does not carry the same favourable prognosis. HPV-OPSCC often tends to present with large cystic metastases in the cervical lymph nodes, with a clinically and radiologically occult primary. Correct diagnosis of the initial biopsy/cytology specimen is critical for directing further investigations and management. In recognition of its distinct biological behaviour, the 8th edition of the American Joint Commission on Cancer (AJCC 8) has proposed a separate clinical and pathological staging system for HPV-OPSCC compared to that for a conventional primary OSCC or neck metastasis of similar size. The new AJCC staging does not apply to other HPV positive SCC of the head and neck. This review examines the current biology of HPV positive SCC, focusing on HPV-OPSCC. The value and pitfalls of current detection methods of HPV are discussed with an emphasis on the role of the pathologist in the diagnosis and management of HPV positive SCC of the head and neck.