Principles of analytic validation of immunohistochemical assays: Guideline from the College of American Pathologists Pathology and Laboratory Quality Center

Programmed Death Ligand-1 and Tumor Mutation Burden Testing of Patients With Lung Cancer for Selection of Immune Checkpoint Inhibitor Therapies: Guideline From the College of American Pathologists, Association for Molecular Pathology, International Association for the Study of Lung Cancer, Pulmonary Pathology Society, and LUNGevity Foundation

CONTEXT.—

Rapid advancements in the understanding and manipulation of tumor-immune interactions have led to the approval of immune therapies for patients with non-small cell lung cancer. Certain immune checkpoint inhibitor therapies require the use of companion diagnostics, but methodologic variability has led to uncertainty around test selection and implementation in practice.

OBJECTIVE.—

To develop evidence-based guideline recommendations for the testing of immunotherapy/immunomodulatory biomarkers, including programmed death ligand-1 (PD-L1) and tumor mutation burden (TMB), in patients with lung cancer.

DESIGN.—

The College of American Pathologists convened a panel of experts in non-small cell lung cancer and biomarker testing to develop evidence-based recommendations in accordance with the standards for trustworthy clinical practice guidelines established by the National Academy of Medicine. A systematic literature review was conducted to address 8 key questions. Using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach, recommendations were created from the available evidence, certainty of that evidence, and key judgments as defined in the GRADE Evidence to Decision framework.

RESULTS.—

Six recommendation statements were developed.

CONCLUSIONS.—

This guideline summarizes the current understanding and hurdles associated with the use of PD-L1 expression and TMB testing for immune checkpoint inhibitor therapy selection in patients with advanced non-small cell lung cancer and presents evidence-based recommendations for PD-L1 and TMB testing in the clinical setting.

Principles of Analytic Validation of Immunohistochemical Assays: Guideline Update

CONTEXT.—

In 2014, the College of American Pathologists developed an evidence-based guideline to address analytic validation of immunohistochemical assays. Fourteen recommendations were offered. Per the National Academy of Medicine standards for developing trustworthy guidelines, guidelines should be updated when new evidence suggests modifications.

OBJECTIVE.—

To assess evidence published since the release of the original guideline and develop updated evidence-based recommendations.

DESIGN.—

The College of American Pathologists convened an expert panel to perform a systematic review of the literature and update the original guideline recommendations using the Grading of Recommendations Assessment, Development and Evaluation approach.

RESULTS.—

Two strong recommendations, 1 conditional recommendation, and 12 good practice statements are offered in this updated guideline. They address analytic validation or verification of predictive and nonpredictive assays, and recommended revalidation procedures following changes in assay conditions.

CONCLUSIONS.—

While many of the original guideline statements remain similar, new recommendations address analytic validation of assays with distinct scoring systems, such as programmed death receptor-1 and analytic verification of US Food and Drug Administration approved/cleared assays; more specific guidance is offered for validating immunohistochemistry performed on cytology specimens.

Erythroblastosis Transformation-Specific Regulated Gene 1 (ERG) Immunohistochemistry in the Diagnosis of Acute Myeloid Leukemia

INTRODUCTION

The erythroblastosis transformation-specific regulated gene 1 (ERG) is a transcription factor that can be used as an immunohistochemical (IHC) marker in the diagnosis and prognostication of malignancy. ERG was initially used in prostate cancer; however, it is a useful marker in extramedullary myeloid disease. Patients with acute myeloid leukemia (AML), dry bone marrow aspirate, and CD34, CD117-negative blast cells can be in a diagnostic dilemma. This audit aimed to (a) validate ERG IHC in bone marrow trephine samples, (b) quantify ERG IHC positivity in an AML cohort, and correlate concordance with CD34 and CD117 IHC, when available, and (c) to see whether ERG is a useful adjunct in the diagnosis of cases of AML.

METHODS

A retrospective audit was completed of all new and relapsed cases of AML over one year at a single center. For inclusion, patients needed a trephine specimen at presentation, and all had a hematoxylin and eosin(H&E) specimen, ERG IHC, and at least one or both of CD34 and CD117 IHC. Four pathologists independently assessed the stains quantitatively and qualitatively in comparison to the morphology seen on the H&E sample. The kappa value was used to assess agreement.

RESULTS

Seventeen patients with AML met the inclusion criteria. All specimens had H&E, CD34, and ERG stains; 9/17 (53%) had CD117 IHC. ERG demonstrated high concordance with blast cells on H&E morphology, with a high agreement among pathologists. Qualitatively, pathologists recognized that ERG spared lymphoid nodules; however, it also stained granulocytes at various maturation stages.

CONCLUSION

ERG is a sensitive marker for the diagnosis of AML. ERG can help visualize blast cells that have been confirmed by ancillary tests. More research into the utility of ERG in AML diagnostics is recommended.

Facts and Hopes on Biomarkers for Successful Early Clinical Immunotherapy Trials: Innovative Patient Enrichment Strategies

Despite the clinical validation and unequivocal benefit to patients, the development of cancer immunotherapies is facing some key challenges and the attrition rate in early phases of development remains high. Identifying the appropriate patient population that would benefit most from the drug is on the critical path for successful clinical development. We believe that a systematic implementation of patient enrichment strategies early in the drug development process and trial design, is the basis for an innovative, more efficient, and leaner clinical development to achieve earlier a clear proof of concept or proof of failure. In this position article, we will describe and propose key considerations for the implementation of patient enrichment strategies as an opportunity to provide decision-enabling data earlier in the drug development process. We introduce an innovative multidimensional tool for immuno-oncology drug development that focuses on facilitating the identification and prioritization of enrichment-relevant biomarkers, based on the drug mechanism of action. To illustrate its utility, we discuss patient enrichment examples and use a case in the field of cancer immunotherapy, together with technical and regulatory considerations. Overall, we propose to implement fit for purpose enrichment strategies for all investigational drugs as early as possible in the development process. We believe that this will increase the success rate of immuno-oncology clinical trials, and eventually bring new and better medicines to patients faster.

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.

Validation and interpretation of Pan-TRK immunohistochemistry: a practical approach and challenges with interpretation

OBJECTIVES

Actionable, solid tumor activating neurotrophic receptor tyrosine kinase (NTRK) fusions are best detected via nucleic acid-based assays, while Pan-TRK immunohistochemistry (IHC) serves as a reasonable screening modality. We describe a practical and cost-effective approach to validate pan-TRK and discuss challenges that may be encountered.

METHODS

Pan-TRK Clone EPR17341 was validated in accordance with the 2014 consensus statements set forth by the College of American Pathologists. Confirmation of IHC results were guided by the European Society of Medical Oncology recommendations for standard methods to detect NTRK fusions.

RESULTS

Within 36 samples, ETV6-NTRK3 (n = 8) and TPM4-NTRK3 (n = 1) fusions were confirmed. ETV6-NTRK3 fusion positive cases revealed cytoplasmic and nuclear staining. A TPM4-NTRK3 fusion positive high grade malignant peripheral nerve sheath tumor revealed diffuse cytoplasmic staining. A high grade ovarian serous carcinoma revealed focal punctate staining and revealed a non-actionable NTRK1 truncation at intron 2. Diffuse cytoplasmic staining was observed in a case of fusion-negative polymorphous adenocarcinoma. Wild-type expression of TRK in pulmonary meningothelial-like nodules was discovered following a false-positive IHC interpretation.

CONCLUSION

Pan-TRK IHC shows some utility as a diagnostic and surrogate marker for NTRK screening however, physiologic or non-specific expression may lead to false-positive results.

Belgian Recommendations for Analytical Verification and Validation of Immunohistochemical Tests in Laboratories of Anatomic Pathology

Analytical verification and validation of immunohistochemical (IHC) tests and their equipment are common practices for today's anatomic pathology laboratories. Few references or guidelines are available on how this should be performed. The study of Sciensano (the Belgian national competent authority regarding licensing of medical laboratories) performed in 2016, demonstrated a significant interlaboratory variation in validation procedures of IHC tests among Belgian laboratories. These results suggest the unavailability of practical information on the approach to the verification and validation of these tests. The existing Belgian Practice Guideline for the implementation of a quality management system in anatomic pathology laboratories has been reviewed to meet this demand and, in addition, to prepare the laboratories for the EU-IVD revised regulations (IVDR). This paper describes Belgian recommendations for the verification and validation of IHC tests before implementation, for ongoing validation, and for revalidation. For each type of test (according to the IVDR classification and the origin) and its intended use (purpose), it addresses how to perform analytical verification/validation by recommending: (1) the number of cases in the validation set, (2) the performance characteristics to be evaluated, (3) the objective acceptance criteria, (4) the evaluation method for the obtained results, and (5) how and when to revalidate. A literature study and a risk analysis taking into account the majority of variables regarding verification/validation of methods have been performed, resulting in an expert consensus recommendation that is a compromise among achievability, affordability, and patient safety. This new consensus recommendation has been incorporated in the aforementioned ISO 15189:2012-based Practice Guideline.

An overview of the detection of bovine respiratory disease complex pathogens using immunohistochemistry: emerging trends and opportunities

The bovine respiratory disease complex (BRDC) is caused by a variety of pathogens, as well as contributing environmental and host-related risk factors. BRDC is the costliest disease for feedlot cattle globally. Immunohistochemistry (IHC) is a valuable tool for enhancing our understanding of BRDC given its specificity, sensitivity, cost-effectiveness, and capacity to provide information on antigen localization and immune response. Emerging trends in IHC include the use of multiplex IHC for the detection of coinfections, the use of digital imaging and automation, improved detection systems using enhanced fluorescent dyes, and the integration of IHC with spatial transcriptomics. Overall, identifying biomarkers for early detection, utilizing high-throughput IHC for large-scale studies, developing standardized protocols and reagents, and integrating IHC with other technologies are some of the opportunities to enhance the accuracy and applicability of IHC. We summarize here the various techniques and protocols used in IHC and highlight their current and potential role in BRDC research.

Global Ring Study to Investigate the Comparability of Total Assay Performance of Commercial Claudin 18 Antibodies for Evaluation in Gastric Cancer

Claudin 18.2 (CLDN18.2), the dominant isoform of CLDN18 in gastric tissues, is a highly specific tight junction protein of the gastric mucosa with variably retained expressions in gastric and gastroesophageal junction cancers. Additionally, CLDN18.2-targeted treatment with zolbetuximab, in combination with chemotherapy, has recently been assessed in 2 phase-III studies of patients with HER2-negative, locally advanced, unresectable, or metastatic gastric or gastroesophageal junction adenocarcinoma. These trials used the investigational VENTANA CLDN18 (43-14A) RxDx immunohistochemistry (IHC) assay on the Ventana BenchMark platform to identify patients eligible for CLDN18.2-targeted treatment. We report the findings of a global ring study evaluating the analytical comparability of concordance of the results of 3 CLDN18 antibodies (Ventana, LSBio, and Novus) stained on 3 IHC-staining platforms (Ventana, Dako, and Leica). A tissue microarray (TMA), comprising 15 gastric cancer cases, was stained by 27 laboratories across 11 countries. Each laboratory stained the TMAs using at least 2 of the 3 evaluated CLDN18 antibodies. Stained TMAs were assessed and scored using an agreed IHC-scoring algorithm, and the results were collated for statistical analysis. The data confirmed a high level of concordance for the VENTANA CLDN18 (43-14A; Ventana platform only) and LSBio antibodies on both the Dako and Leica platforms, with accuracy, precision, sensitivity, and specificity rates all reaching a minimum acceptable ≥85% threshold and good-to-excellent levels of concordance as measured by Cohen's kappa coefficient. The Novus antibody showed the highest level of variability against the reference central laboratory results for the same antibody/platform combinations. It also failed to meet the threshold for accuracy and sensitivity when used on either the Dako or Leica platform. These results demonstrated the reliability of IHC testing for CLDN18 expression in gastric tumor samples when using commercially available platforms with an appropriate methodology and primary antibody selection.

Impact of formalin fixation on mismatch repair protein evaluation by immunohistochemistry

Mismatch repair/microsatellite instability (MMR/MSI) status in colorectal cancer (CRC) has become fundamental as a diagnostic, prognostic, and predictive factor. MMR immunohistochemistry (IHC) is considered a simple and reliable approach; however, its effectiveness depends on pre-analytic factors. Aim of this study was to investigate the impact of different fixation times/protocols on MMR protein IHC quality. Left over tissue from surgically resected CRC samples (cold ischemia time < 30 min) where fixed as follows: standard formalin fixation (24-48 h); hypo-fixation (<20 h); hyper-fixation (>90 h); cold (4°C) fixation (24-48 h); standard fixation for small sample size (0.5×0.5 cm). Samples for each group were collected from 30 resected CRC and the following parameters were evaluated on 600 immunohistochemical stains: intensity of expression; patchiness of staining; presence of central artefact. Forty-six immunoreactions were inadequate (score 0 intensity), the majority regarding MLH1 or PMS2 in the hypo-fixation group (47.8%), followed by the hyper-fixation group (28.1%); cold formalin fixation showed the least inadequate cases. Patchiness and central artefact were more frequent in hypo-fixation and standard fixation group compared to the others. MLH1 (closely followed by PMS2) performed worse with regard to immunostaining intensity (p=0.0002) in the standard and in the hypo-fixation group (p< 0.00001). Using a small sample size improved patchiness/central artefacts. This is the first study specifically created to evaluate the impact of fixation on MMR protein IHC, showing that both formalin hypo- and hyper-fixation can cause problems; 24-h formalin fixation as well as cold (4°C) formalin fixation are recommended for successful IHC MMR evaluation.

Optimising multiplex immunofluorescence staining for characterising the tumour immune micro-environment

Exploring the tumour microenvironment provides insight into the unique interaction between the host and tumour. Ultimately, its study improves understanding of how an individual mounts and achieves an anti-tumour immune response. In the context of colorectal cancer, immune biomarkers within the tumour microenvironment outperform traditional histopathological staging in predicting disease recurrence. Multiplex immunofluorescence enables simultaneous assessment of multiple markers to provide a highly accurate classification of immune cells and their spatial characterisation relative to tumour tissue. Further, automated slide staining provides staining consistency and reduces labour costs. Image acquisition using a non-spectral scanner allows more researchers to utilise multiplexed immunofluorescence for translational research. Herein we describe the optimisation process of conducting automated staining using a five-colour, tyramide signal amplification-based multiplex immunofluorescence panel. Using antibodies against CD3, CD8, CD103 and cytokeratin, the panel characterises T cell populations within human colorectal adenocarcinoma tissue. We provide an overview of primary antibody titration and the development of tyramide signal amplification immunofluorescence monoplex assays. We detail the processes of antibody stripping and the role of exogenous horseradish peroxidase inhibition to facilitate multiplexing. An account of determining the staining sequence and fluorophore assignment is provided. We describe image acquisition using a standard fluorescence microscope slide scanner and the management of spectral crosstalk using this system. Finally, we briefly document the digital image analysis required to characterise cells and determine their spatial distribution within the colorectal tumour microenvironment.

Comparison of SP142 and 22C3 PD-L1 assays in a population-based cohort of triple-negative breast cancer patients in the context of their clinically established scoring algorithms

BACKGROUND

Immunohistochemical (IHC) PD-L1 expression is commonly employed as predictive biomarker for checkpoint inhibitors in triple-negative breast cancer (TNBC). However, IHC evaluation methods are non-uniform and further studies are needed to optimize clinical utility.

METHODS

We compared the concordance, prognostic value and gene expression between PD-L1 IHC expression by SP142 immune cell (IC) score and 22C3 combined positive score (CPS; companion IHC diagnostic assays for atezolizumab and pembrolizumab, respectively) in a population-based cohort of 232 early-stage TNBC patients.

RESULTS

The expression rates of PD-L1 for SP142 IC ≥ 1%, 22C3 CPS ≥ 10, 22C3 CPS ≥ 1 and 22C3 IC ≥ 1% were 50.9%, 27.2%, 53.9% and 41.8%, respectively. The analytical concordance (kappa values) between SP142 IC+ and these three different 22C3 scorings were 73.7% (0.48, weak agreement), 81.5% (0.63) and 86.6% (0.73), respectively. The SP142 assay was better at identifying 22C3 positive tumors than the 22C3 assay was at detecting SP142 positive tumors. PD-L1 (CD274) gene expression (mRNA) showed a strong positive association with all two-categorical IHC scorings of the PD-L1 expression, irrespective of antibody and cut-off (Spearman Rho ranged from 0.59 to 0.62; all p-values < 0.001). PD-L1 IHC positivity and abundance of tumor infiltrating lymphocytes were of positive prognostic value in univariable regression analyses in patients treated with (neo)adjuvant chemotherapy, where it was strongest for 22C3 CPS ≥ 10 and distant relapse-free interval (HR = 0.18, p = 0.019). However, PD-L1 status was not independently prognostic when adjusting for abundance of tumor infiltrating lymphocytes in multivariable analyses.

CONCLUSION

Our findings support that the SP142 and 22C3 IHC assays, with their respective clinically applied scoring algorithms, are not analytically equivalent where they identify partially non-overlapping subpopulations of TNBC patients and cannot be substituted with one another regarding PD-L1 detection. Trial registration The Swedish Cancerome Analysis Network - Breast (SCAN-B) study, retrospectively registered 2nd Dec 2014 at ClinicalTrials.gov; ID NCT02306096.

Analytical Validation of an Immunohistochemical 7-Biomarker Prognostic Assay (immunoprint®) for Early-Stage Cutaneous Melanoma in Archival Tissue of Patients with AJCC v8 T2-T3 Disease

Selected patients with early-stage melanoma have a "hidden high risk" of poor oncologic outcomes. They might benefit from clinical trials, and ultimately, if warranted by trial results, judicious everyday use of adjuvant therapy. A promising tool to identify these individuals is the immunoprint® assay. This immunohistochemical 7-biomarker prognostic test was clinically validated in three independent cohorts (N = 762) to classify early-stage patients as high-risk or low-risk regarding melanoma recurrence and mortality. Using College of American Pathologists (CAP) recommendations, we analytically validated this assay in primary melanoma specimens (N = 20 patients). We assessed assay precision by determining consistency of risk classification under repeated identical conditions (repeatability) or across varying conditions (reproducibility), involving separate assay runs, operators (laboratory scientists), and/or observers (e.g., dermatopathologists). Reference classification was followed by five analytical validation phases: intra-run/intra-operator, intra-observer, inter-run, inter-operator, and inter-observer. Concordance of classifications in each phase was assessed via Fleiss' kappa (primary endpoint) and percent agreement (secondary endpoint). Seven-marker signature classification demonstrated high consistency across validation categories (Fleiss' kappa 0.864-1.000; overall percent agreement 95-100%), in 9/10 cases, exceeding, and in 1/10 cases, closely approaching, CAP's recommended 0.9 level. The 7-marker assay has now been verified to provide excellent repeatability, reproducibility, and precision, besides having been clinically validated.

Detecting Human Epidermal Growth Factor Receptor 2 (HER2) Amplification: Proof of Concept of an Alternative Approach

BACKGROUND

There are multiple genes that are co-amplified along with human epidermal growth factor receptor 2 (HER2) in chromosome 17. GRB7 and PGAP3 are two such genes. We hypothesize that the protein products of these genes may serve as immunohistochemistry (IHC) markers for detecting HER2 amplification in breast cancer.

METHODS

Tissue sections from one hundred and thirty-five primary breast carcinoma cases were subjected to immunohistochemical staining for antibodies against HER2, GRB7, and PGAP3 and graded on a scale of 1 to 3. Both membranous staining and cytoplasmic staining were assessed for GRB7 and PGAP3. For equivocal HER2 IHC positivity, fluorescent in situ hybridization was performed to get the final HER2 status.

RESULTS

IHC staining for GRB7 and PGAP 3 was a moderate to strong predictor for HER2 status (area under the curve (AUC) of 0.768, 0.868,0.754, and 0.790 for GRB7 membranous staining, GRB7 cytoplasmic staining, PGAP3 membranous staining, and PGAP3 cytoplasmic staining respectively). A combination of GRB7 cytoplasmic and PGAP3 membranous staining resulted in an AUC of 0.905 (95% CI 0.855-0.954), while a combination of GRB7 and PGAP3 cytoplasmic staining resulted in an AUC of 0.902 (95% CI 0.851-0.953).

CONCLUSION

The point estimates for the AUC of GRB7 and combined GRB7 and PGAP3 in predicting the AUC suggest a strong predictive ability of these markers to predict HER2. With further refinement in technique, cytoplasmic staining and membranous IHC staining for GRB7 and PGAP3 have potential to serve as surrogate markers for HER2 status. The strategy of using protein products of co-amplified genes of HER2 is likely to be successful in technical validation.

Multicenter Harmonization Study of Pan-Trk Immunohistochemistry for the Detection of NTRK3 Fusions

Pan-Trk immunohistochemistry has been described as a screening test for the detection of NTRK fusions in a broad spectrum of tumor types. However, pan-Trk testing in the clinical setting may be limited by many factors, including analytical parameters such as clones, platforms, and protocols used. This study aimed to harmonize pan-Trk testing using various clones and immunohistochemical (IHC) platforms and to evaluate the level of analytical variability across pathology laboratories. We developed several IHC pan-Trk assays using clones EPR17341 (Abcam) and A7H6R (Cell Signaling Technology) on Ventana/Roche, Agilent, and Leica platforms. To compare them, we sent unstained sections of a tissue microarray containing 9 cases with NTRK3 fusions to participating laboratories, to perform staining on Ventana/Roche (10 centers), Agilent (4 centers), and Leica (3 centers) platforms. A ready-to-use pan-Trk IVD assay (Ventana/Roche) was also performed in 3 centers. All slides were centrally and blindly reviewed for the percentage of stained tumor cells. Laboratory-developed tests with clone EPR17341 were able to detect pan-Trk protein expression in all cases, whereas lower rates of positivity were observed with clone A7H6R. Moderate to strong variability of the positive cases rate was observed with both antibodies in each IHC platforms type and each of the positivity cut points evaluated (≥1%, ≥10%, and ≥50% of stained tumor cells). The rate of false-negative cases was lower when pan-Trk staining was assessed with the lowest positivity threshold (≥1%). In conclusion, most evaluated pan-Trk IHC laboratory-developed tests were able to detect NTRK3-fusion proteins; however, a significant analytical variability was observed between antibodies, platforms, and centers.

p53 as Exemplar Next-Generation Immunohistochemical Marker: A Molecularly Informed, Pattern-Based Approach, Methodological Considerations, and Pan-Cancer Diagnostic Applications

This review is based on a webinar I presented for the International Society for Immunohistochemistry and Molecular Morphology (ISIMM) in February 2022. It is intended that all ISIMM webinars will ultimately be published in AIMM as review articles. This work is also dedicated to Clive Taylor, who has deeply impacted my career. It presents a molecularly informed, pattern-based approach to p53 immunohistochemistry interpretation, methodological considerations (ie, antibody selection, optimization, validation, controls, and external quality assessment), and pan-cancer diagnostic applications, including those drawn from gastrointestinal, genitourinary, gynecological, neuroendocrine, hematologic, and neuropathology. It intends to prove the thesis statement that p53 is an exemplar next-generation immunohistochemical marker "born" ahead of its time.

A biomarker assay validation approach tailored to the context of use and bioanalytical platform

It is widely acknowledged by the bioanalytical and biomarker community that biomarker assay validations should be fit-for-purpose depending on the context of use. The challenge is how to consistently apply these principles in teams responsible for measuring a disparate array of biomarkers, often on multiple analytical platforms, at various stages of the drug discovery and development pipeline and across diverse biology focus areas. To drive consistency, while maintaining the necessary flexibility to allow validations to be driven by scientific rationale and taking into consideration the context of use and associated biological and (pre)analytical factors, a framework applicable across biomarker assays was developed. Herein the authors share their perspective to engage in the ongoing conversation around fit-for-purpose biomarker assay validation.

Immunohistochemical detection of MUC5AC and MUC5B mucins in ferrets

OBJECTIVE

Cystic fibrosis (CF) is a genetic condition that causes abnormal mucus secretions in affected organs. MUC5AC and MUC5B are gel-forming mucins and frequent targets for investigations in CF tissues. Our objective was to qualify MUC5AC and MUC5B immunohistochemical techniques to provide a useful tool to identify, localize and interpret mucin expression in ferret tissues.

RESULTS

MUC5AC and MUC5B mucins were detected most commonly in large airways and least in small airways, consistent with reported goblet cell density in airway surface epithelia. We evaluated whether staining method affected the detection of goblet cell mucins in serial sections of bronchial surface epithelia. Significant differences between stains were not observed suggesting common co-expression MUC5AC and MUC5B proteins in goblet cells of airway surface epithelia. Gallbladder and stomach tissues are reported to have differential mucin enrichment, so we tested these tissues in wildtype ferrets. Stomach tissues were enriched in MUC5AC and gallbladder tissues enriched in MUC5B, mucin enrichment similar to human tissues. Mucin immunostaining techniques were further qualified for specificity using lung tissue from recently generated MUC5AC-/- and MUC5B-/- ferrets. Qualified techniques for MUC5AC and MUC5B immunohistochemistry will be useful tools for mucin tissue studies in CF and other ferret models.

Analytical validation of the 7-gene biosignature for prediction of recurrence risk and radiation therapy benefit for breast ductal carcinoma in situ

Purpose

Ductal carcinoma in situ (DCIS), is a noninvasive breast cancer, representing 20-25% of breast cancer diagnoses in the USA. Current treatment options for DCIS include mastectomy or breast-conserving surgery (BCS) with or without radiation therapy (RT), but optimal risk-adjusted treatment selection remains a challenge. Findings from past and recent clinical trials have failed to identify a 'low risk' group of patients who do not benefit significantly from RT after BCS. To address this unmet need, a DCIS biosignature, DCISionRT (PreludeDx, Laguna Hills, CA), was developed and validated in multiple cohorts. DCISionRT is a molecular assay with an algorithm reporting a recurrence risk score for patients diagnosed with DCIS intended to guide DCIS treatment. In this study, we present results from analytical validity, performance assessment, and clinical performance validation and clinical utility for the DCISionRT test comprised of multianalyte assays with algorithmic analysis.

Methods

The analytical validation of each molecular assay was performed based on the Clinical and Laboratory Standards Institute (CLSI) guidelines Quality Assurance for Design Control and Implementation of Immunohistochemistry Assays and the College of American Pathologists/American Society of Clinical Oncology (CAP/ASCO) recommendations for analytic validation of immunohistochemical assays.

Results

The analytic validation showed that the molecular assays that are part of DCISionRT test have high sensitivity, specificity, and accuracy/reproducibility (≥95%). The analytic precision of the molecular assays under controlled non-standard conditions had a total standard deviation of 6.6 (100-point scale), where the analytic variables (Lot, Machine, Run) each contributed <1% of the total variance. Additionally, the precision in the DCISionRT test result (DS) had a 95%CI ≤0.4 DS units under controlled non-standard conditions (Day, Lot, and Machine) for molecular assays over a wide range of clinicopathologic factor values. Clinical validation showed that the test identified 37% of patients in a low-risk group with a 10-year invasive IBR rate of ~3% and an absolute risk reduction (ARR) from RT of 1% (number needed to treat, NNT=100), while remaining patients with higher DS scores (elevated-risk) had an ARR for RT of 9% (NNT=11) and 96% clinical sensitivity for RT benefit.

Conclusion

The analytical performance of the PreludeDx DCISionRT molecular assays was high in representative formalin-fixed, paraffin-embedded breast tumor specimens. The DCISionRT test has been analytically validated and has been clinically validated in multiple peer-reviewed published studies.

Validation of PRKCB Immunohistochemistry as a Biomarker for the Diagnosis of Ewing Sarcoma

Background: Ewing sarcoma (ES) can be confirmed by identifying the EWSR1-FLI1 fusion transcript. This study is to investigate whether immunostaining (IHC) of PRKCB-a protein directly regulated by EWSR1-FLI1 is a surrogate maker for diagnosing ES in routine practice. Methods: Microarray gene expression analyses were conducted. RKCB IHC was applied to 69 ES confirmed by morphology and molecular methods, and 41 non-Ewing small round cell tumors. EWSR1 rearrangement, EWSR1-FLI1 fusion or t(11;22)(q24;q12) were identified by fluorescence in situ hybridization, reverse transcriptase polymerase chain reaction, or cytogenetic analysis, respectively. Results: Gene array analyses showed significant overexpression of the PRKCB in ES. PRKCB IHC was positive in 19 cases of ES with EWSR1-FLI1 fusion, 3 cases with cytogenetic 11:22 translocation and 59 cases with EWSR1 rearrangement while negative in only one EWSR1 rearranged case. PRKCB IHC is sensitive (98%) and specific (96%) in detecting EWSR1 rearranged ES. Conclusions: PRKCB is a reliable antibody for diagnosing ES in routine practice.

European Society of Toxicologic Pathology (Pathology 2.0 Molecular Pathology Special Interest Group): Review of In Situ Hybridization Techniques for Drug Research and Development

In situ hybridization (ISH) is used for the localization of specific nucleic acid sequences in cells or tissues by complementary binding of a nucleotide probe to a specific target nucleic acid sequence. In the last years, the specificity and sensitivity of ISH assays were improved by innovative techniques like synthetic nucleic acids and tandem oligonucleotide probes combined with signal amplification methods like branched DNA, hybridization chain reaction and tyramide signal amplification. These improvements increased the application spectrum for ISH on formalin-fixed paraffin-embedded tissues. ISH is a powerful tool to investigate DNA, mRNA transcripts, regulatory noncoding RNA, and therapeutic oligonucleotides. ISH can be used to obtain spatial information of a cell type, subcellular localization, or expression levels of targets. Since immunohistochemistry and ISH share similar workflows, their combination can address simultaneous transcriptomics and proteomics questions. The goal of this review paper is to revisit the current state of the scientific approaches in ISH and its application in drug research and development.

Cell blocks in cytology: review of preparation methods, advantages, and limitations

Cell blocks are cytologic preparations that are processed as paraffin embedded blocks in a manner comparable to formalin-fixed paraffin-embedded tissue in surgical pathology. In addition to serving as an adjunct to other cytologic preparations for morphologic diagnosis, cell blocks play an increasingly important role as they yield tissue sections that can be utilized for ancillary testing such as immunohistochemical stains and molecular studies. While essentially universally viewed as playing a pivotal role in cytopathology practice, there are various factors that limit their use in practice and contribute to dissatisfaction with cell block quality. Cell block preparation, as opposed to tissue processing in surgical pathology, is more variable with many different protocols in use today. This review explores the most commonly used cell block preparation techniques currently in use with review of the unique advantages and limitations each method presents. The goal of this work is to serve as a resource that can aid in making more informed decisions about which cell block protocol may work best for individual laboratories.

Using American Type Culture Collection Cell Lines to Evaluate Interlaboratory Variables for Estrogen Receptor and Human Epidermal Growth Factor Receptor 2 Immunostaining

CONTEXT.—

Most laboratories currently use patient tissues for validating immunohistochemical stains.

OBJECTIVE.—

To explore advantages of using cell lines with known antigenicity as a validation method.

DESIGN.—

Five American Type Culture Collection (ATCC) cell lines with known negative, low positive, and moderate to strong estrogen receptor (ER) expression as well as negative, equivocal, and positive human epidermal growth factor receptor 2 (HER2) expression were cultured and made into cell blocks. One block from each cell line was fixed in formalin and another in ethanol before cell block preparation. Two sets of paired unstained slides from each block were sent to 10 different laboratories for HER2 and ER staining to be stained on runs from different days according to each laboratory's defined protocol.

RESULTS.—

The 10 study participants evaluated 40 slides in a blinded fashion. For ER expression, all 80 interpretations for the ER strong and moderate positive cell lines had the target ER-positive result, and 74 of 80 ER-negative cell lines (92.5%) had agreement with the intended negative result. The ER low positive cell line showed varied but positive expression among all observers. The HER2 (3+)-positive cell lines yielded a target interpretation of 3+ in 65 of 80 interpretations (81.2%). For the HER2-negative cell line 69 of 78 interpretations (88.5%) were consistent with the target response (0 or 1+). No significant variation was observed between the ethanol- and non-ethanol-exposed cell lines, or between runs by the same laboratory. Variation from target results clustered within laboratories.

CONCLUSIONS.—

This study indicates that variability between laboratories can be identified by using cell lines for quantitative or semiquantitative immunohistochemistry when using cultured cell lines of known antigenicity. These cell lines could potentially play a role in aiding anatomic pathology laboratories in validating immunohistochemistry tests for formalin- and ethanol-fixed tissues.

Brazilian Expert Consensus for NTRK Gene Fusion Testing in Solid Tumors

Oncogenic neurotrophic tropomyosin receptor kinase gene fusions occur in less than 1% of common cancers. These mutations have emerged as new biomarkers in cancer genomic profiling with the approval of selective drugs against tropomyosin receptor kinase fusion proteins. Nevertheless, the optimal pathways and diagnostic platforms for this biomarker's screening and genomic profiling have not been defined and remain a subject of debate. A panel of national experts in molecular cancer diagnosis and treatment was convened by videoconference and suggested topics to be addressed in the literature review. The authors proposed a testing algorithm for oncogenic neurotrophic tropomyosin receptor kinase gene fusion screening and diagnosis for the Brazilian health system. This review aims to discuss the latest literature evidence and international consensus on neurotrophic tropomyosin receptor kinase gene fusion diagnosis to devise clinical guidelines for testing this biomarker. We propose an algorithm in which testing for this biomarker should be requested to diagnose advanced metastatic tumors without known driver mutations. In this strategy, Immunohistochemistry should be used as a screening test followed by confirmatory next-generation sequencing in immunohistochemistry-positive cases.

Recommendations for optimizing the use of cytology in the diagnosis and management of patients with lung cancer

Non-small cell lung cancer (NSCLC) is one of the oncological entities with the greatest evolution in molecular diagnosis due to the large number of diagnostic biomarkers and new treatments approved by international regulatory agencies. An accurate, early diagnosis using the least amount of tissue is the goal for the establishing and developing precision medicine for these patients. Rapid on-site evaluation (ROSE) provides cytological samples of optimal quantity and quality for a complete diagnosis of NSCLC. The usefulness of cytological samples has been demonstrated, not only for massive parallel sequencing but also for the quantification of the expression of programmed death-ligand 1 (PD-L1) and tumour mutational burden (TMB). Pre-analytical, analytical, and post-analytical recommendations are made for the management and appropriate use of cytological samples in order to obtain all the information necessary for the diagnosis and treatment of patients with NSCLC according to current quality parameters.

Best Practices in CD30 Immunohistochemistry Testing, Interpretation, and Reporting: An Expert Panel Consensus

CONTEXT.—

Although CD30 testing is an established tool in the diagnostic workup of lymphomas, it is also emerging as a predictive biomarker that informs treatment. The current definition of CD30 positivity by immunohistochemistry is descriptive and based on reactivity in lymphomas that are defined by their universal strong expression of CD30, rather than any established threshold. Challenges include inconsistencies with preanalytic variables, tissue processing, pathologist readout, and with the pathologist and oncologist interpretation of reported results.

OBJECTIVE.—

To develop and propose general best practice recommendations for reporting CD30 expression by immunohistochemistry in lymphoma biopsies to harmonize practices across institutions and facilitate assessment of its significance in clinical decision-making.

DESIGN.—

Following literature review and group discussion, the panel of 14 academic hematopathologists and 2 clinical/academic hematologists/oncologists divided into 3 working groups. Each working group was tasked with assessing CD30 testing by immunohistochemistry, CD30 expression readout, or CD30 expression interpretation.

RESULTS.—

Panel recommendations were reviewed and discussed. An online survey was conducted to confirm the consensus recommendations.

CONCLUSIONS.—

CD30 immunohistochemistry is required for all patients in whom classic Hodgkin lymphoma and any lymphoma within the spectrum of peripheral T-cell lymphoma are differential diagnostic considerations. The panel reinforced and summarized that immunohistochemistry is the preferred methodology and any degree of CD30 expression should be reported. For diagnostic purposes, the interpretation of CD30 expression should follow published guidelines. To inform therapeutic decisions, report estimated percent positive expression in tumor cells (or total cells where applicable) and record descriptively if nontumor cells are positive.

Nationwide differences in cytology fixation and processing methods and their impact on interlaboratory variation in PD-L1 positivity

Programmed death ligand-1 (PD-L1) immunostaining, which aids clinicians in decision-making on immunotherapy for non-small cell lung cancer (NSCLC) patients, is sometimes performed on cytological specimens. In this study, differences in cytology fixation and cell block (CB) processing between pathology laboratories were assessed, and the influence of these differences on interlaboratory variation in PD-L1 positivity was investigated. Questionnaires on cytology processing were sent to all Dutch laboratories. Information gathered from the responses was added to data on all Dutch NSCLC patients with a mention of PD-L1 testing in their cytopathology report from July 2017 to December 2018, retrieved from PALGA (the nationwide network and registry of histo- and cytopathology in the Netherlands). Case mix-adjusted PD-L1 positivity rates were determined for laboratories with known fixation and CB method. The influence of differences in cytology processing on interlaboratory variation in PD-L1 positivity was assessed by comparing positivity rates adjusted for differences in the variables fixative and CB method with positivity rates not adjusted for differences in these variables. Twenty-eight laboratories responded to the survey and reported 19 different combinations of fixation and CB method. Interlaboratory variation in PD-L1 positivity was assessed in 19 laboratories. Correcting for differences in the fixative and CB method resulted in a reduction (from eight (42.1%) to five (26.3%)) in the number of laboratories that differed significantly from the mean in PD-L1 positivity. Substantial variation in cytology fixation and CB processing methods was observed between Dutch pathology laboratories, which partially explains the existing considerable interlaboratory variation in PD-L1 positivity.

Highlights from the 7th Oncological Pathology Conference 'Pathological Anatomy in the context of the National Cancer Law: An overview of the Latin American experience', 15, 22 and 23 July 2022, Trujillo, Peru

The seventh session of the Oncological Pathology Conference (JoPaO) entitled 'Pathological Anatomy in the context of the National Cancer Law: An overview of the Latin American experience', was held virtually on July 15, 22 and 23. Peru was the headquarters for this event, where 17 national and international professors of high academic standing participated. They interacted in a multidisciplinary context through talks with national panellists and the general public. The recent promulgation of the 'National Cancer Law' fosters the development of discussion forums to analyse the national realities and uphold continuous learning about experiences in other Latin American countries with successful cancer programmes, in which pathology holds a principal role. The topics addressed during this JoPaO included the exchange of Latin American cancer management experiences, an emphasis on investments in and the development of strategic plans to improve care, the use of new technologies, laboratory quality control, and the need to advance scientific research.

Overexpression of ErbB-1 (EGFR) Protein in Eutopic Endometrium of Infertile Women with Severe Ovarian Endometriosis during the ‘Implantation Window’ of Menstrual Cycle

The strong association between endometriosis and infertility is of high clinical significance. High proliferative bias in eutopic endometrium during the secretory phase is a hallmark of endometriosis, which may result in high occurrence of implantation failure and resultant infertility in endometriosis. The ErbB family of proteins regulates the proliferation capacity in the endometrium, potentially causing endometrial hostility to the implantation process in endometriosis. However, our knowledge regarding the involvement of the ErbB family in human endometrium during the window of implantation (WOI) in endometriosis-associated infertility is scant. In the present study, the cellular profiles of immunopositive ErbBs-1 to -4 in the endometrium of endometriosis-free, infertile women (Group 1; n = 11) and in eutopic endometrium of infertile women diagnosed with stage IV ovarian endometriosis (Group 2; n = 13) during the mid-secretory phase were compared using standardized guidelines. Computer-aided standardized combinative analysis of immunoprecipitation in different compartments revealed an overexpression of ErbB-1 in the epithelial, stromal and vascular compartments, along with marginally higher ErbB-3 expression (p < 0.06) in the vascular compartment and ErbB-4 expression (p < 0.05) in the glandular epithelium and stroma in the endometrium during the WOI in women with primary infertility associated with stage IV ovarian endometriosis compared with disease-free endometrium of control infertile women. It appears that changes in ErbBs in the eutopic endometrium during WOI induce anomalous proliferative, inflammatory and angiogenic activities in it, which can antagonize endometrial preparation for embryo implantation in endometriosis. This knowledge appears usable in strategizing methods for the treatment of endometriosis-associated infertility, as well as preempting the oncogenic potential of endometriosis.

Mismatch Repair and Microsatellite Instability Testing for Immune Checkpoint Inhibitor Therapy: Guideline From the College of American Pathologists in Collaboration With the Association for Molecular Pathology and Fight Colorectal Cancer

CONTEXT.—

The US Food and Drug Administration (FDA) approved immune checkpoint inhibitor therapy for patients with advanced solid tumors that have DNA mismatch repair defects or high levels of microsatellite instability; however, the FDA provided no guidance on which specific clinical assays should be used to determine mismatch repair status.

OBJECTIVE.—

To develop an evidence-based guideline to identify the optimal clinical laboratory test to identify defects in DNA mismatch repair in patients with solid tumor malignancies who are being considered for immune checkpoint inhibitor therapy.

DESIGN.—

The College of American Pathologists convened an expert panel to perform a systematic review of the literature and develop recommendations. Using the National Academy of Medicine-endorsed Grading of Recommendations Assessment, Development and Evaluation approach, the recommendations were derived from available evidence, strength of that evidence, open comment feedback, and expert panel consensus. Mismatch repair immunohistochemistry, microsatellite instability derived from both polymerase chain reaction and next-generation sequencing, and tumor mutation burden derived from large panel next-generation sequencing were within scope.

RESULTS.—

Six recommendations and 3 good practice statements were developed. More evidence and evidence of higher quality were identified for colorectal cancer and other cancers of the gastrointestinal (GI) tract than for cancers arising outside the GI tract.

CONCLUSIONS.—

An optimal assay depends on cancer type. For most cancer types outside of the GI tract and the endometrium, there was insufficient published evidence to recommend a specific clinical assay. Absent published evidence, immunohistochemistry is an acceptable approach readily available in most clinical laboratories.

Two Instrument Comparison of Reagents From a US FDA-Approved Assay for the Assessment of Ki-67 in High-Risk Early Breast Cancer

The objective of this study was to measure concordance of results obtained from the US Food and Drug Administration-approved Ki-67 immunohistochemistry MIB-1 pharmDx assay performed on the Dako Omnis automated staining instrument (Omnis) versus results produced from the assay reagents applied using an optimized protocol on the more widely available Autostainer Link 48 (ASL48) platform. Tissue sections obtained from 40 formalin-fixed paraffin-embedded breast carcinoma samples, with available Oncotype DX Breast Recurrence Score (RS) results, were stained. Three certified pathologists scored slides at 3 timepoints, totaling 360 observations for each instrument (N=720 total) using the approved scoring approach. Using the ≥20% cutoff, agreement was calculated with corresponding 2-sided 95% percentile bootstrap confidence intervals (CIs). Pairwise comparisons (N=360) from the interinstrument evaluation, performed with all observers, resulted in 325 (90.3%) concordant outcomes (244 negative and 81 positive) and 35 (9.7%) discordant outcomes. The overall agreement was 90.3% (95% confidence interval, 85.6% to 94.4%). No significant systematic differences were observed between instruments. Specimens scored from the Omnis were on average <1% higher than ASL48, with high correlation and little bias between the continuous Ki-67 scores (concordance correlation coefficient=0.916). Most specimens with a Ki-67 score ≥20% had a RS >25. This study demonstrated that good concordance can be achieved with the reagents run on the ASL48 instrument when using an optimized protocol and standardized scoring.

Challenges and Opportunities for Immunoprofiling Using a Spatial High-Plex Technology: The NanoString GeoMx® Digital Spatial Profiler

Characterization of the tumor microenvironment through immunoprofiling has become an essential resource for the understanding of the complex immune cell interactions and the assessment of biomarkers for prognosis and prediction of immunotherapy response; however, these studies are often limited by tissue heterogeneity and sample size. The nanoString GeoMx^® Digital Spatial Profiler (DSP) is a platform that allows high-plex profiling at the protein and RNA level, providing spatial and temporal assessment of tumors in frozen or formalin-fixed paraffin-embedded limited tissue sample. Recently, high-impact studies have shown the feasibility of using this technology to identify biomarkers in different settings, including predictive biomarkers for immunotherapy in different tumor types. These studies showed that compared to other multiplex and high-plex platforms, the DSP can interrogate a higher number of biomarkers with higher throughput; however, it does not provide single-cell resolution, including co-expression of biomarker or spatial information at the single-cell level. In this review, we will describe the technical overview of the platform, present current evidence of the advantages and limitations of the applications of this technology, and provide important considerations for the experimental design for translational immune-oncology research using this tissue-based high-plex profiling approach.

Detection of SARS-CoV-2 in tissue: the comparative roles of RT-qPCR, in situ RNA hybridization, and immunohistochemistry

INTRODUCTION

The emergence of SARS-CoV-2, the causative agent the COVID-19 pandemic, has led to a rapidly expanding arsenal of molecular diagnostic assays for the detection of viral material in tissue specimens.

AREAS COVERED

We review the value and shortcomings of available tissue-based assays for SARS-CoV-2 detection in formalin-fixed paraffin-embedded (FFPE) tissue, including immunohistochemistry, in situ hybridization, and quantitative reverse transcription PCR (RT-qPCR). The validation, accuracy, and comparative utility of each method is discussed. Subsequently, we identify commercially available antibodies which render the greatest specificity and reproducibility of staining in FFPE specimens.

EXPERT OPINION

We offer expert opinion on the efficacy of such techniques and guidance for future implementation, both clinical and experimental.

Claudin18.2-specific CAR T cells in gastrointestinal cancers: phase 1 trial interim results

Despite success in hematologic malignancies, the treatment landscape of chimeric antigen receptor (CAR) T cell therapy for solid tumors remains limited. Claudin18.2 (CLDN18.2)-redirected CAR T cells showed promising efficacy against gastric cancer (GC) in a preclinical study. Here we report the interim analysis results of an ongoing, open-label, single-arm, phase 1 clinical trial of CLDN18.2-targeted CAR T cells (CT041) in patients with previously treated, CLDN18.2-positive digestive system cancers ( NCT03874897 ). The primary objective was safety after CT041 infusion; secondary objectives included CT041 efficacy, pharmacokinetics and immunogenicity. We treated 37 patients with one of three CT041 doses: 2.5 × 108, 3.75 × 108 or 5.0 × 108 cells. All patients experienced a grade 3 or higher hematologic toxicity. Grade 1 or 2 cytokine release syndrome (CRS) occurred in 94.6% of patients. No grade 3 or higher CRS or neurotoxicities, treatment-related deaths or dose-limiting toxicities were reported. The overall response rate (ORR) and disease control rate (DCR) reached 48.6% and 73.0%, respectively. The 6-month duration of response rate was 44.8%. In patients with GC, the ORR and DCR reached 57.1% and 75.0%, respectively, and the 6-month overall survival rate was 81.2%. These initial results suggest that CT041 has promising efficacy with an acceptable safety profile in patients with heavily pretreated, CLDN18.2-positive digestive system cancers, particularly in those with GC.

Claudin18.2-specific CAR T cells in gastrointestinal cancers: phase 1 trial interim results

Despite success in hematologic malignancies, the treatment landscape of chimeric antigen receptor (CAR) T cell therapy for solid tumors remains limited. Claudin18.2 (CLDN18.2)-redirected CAR T cells showed promising efficacy against gastric cancer (GC) in a preclinical study. Here we report the interim analysis results of an ongoing, open-label, single-arm, phase 1 clinical trial of CLDN18.2-targeted CAR T cells (CT041) in patients with previously treated, CLDN18.2-positive digestive system cancers ( NCT03874897 ). The primary objective was safety after CT041 infusion; secondary objectives included CT041 efficacy, pharmacokinetics and immunogenicity. We treated 37 patients with one of three CT041 doses: 2.5 × 108, 3.75 × 108 or 5.0 × 108 cells. All patients experienced a grade 3 or higher hematologic toxicity. Grade 1 or 2 cytokine release syndrome (CRS) occurred in 94.6% of patients. No grade 3 or higher CRS or neurotoxicities, treatment-related deaths or dose-limiting toxicities were reported. The overall response rate (ORR) and disease control rate (DCR) reached 48.6% and 73.0%, respectively. The 6-month duration of response rate was 44.8%. In patients with GC, the ORR and DCR reached 57.1% and 75.0%, respectively, and the 6-month overall survival rate was 81.2%. These initial results suggest that CT041 has promising efficacy with an acceptable safety profile in patients with heavily pretreated, CLDN18.2-positive digestive system cancers, particularly in those with GC.

Claudin18.2-specific CAR T cells in gastrointestinal cancers: phase 1 trial interim results

Despite success in hematologic malignancies, the treatment landscape of chimeric antigen receptor (CAR) T cell therapy for solid tumors remains limited. Claudin18.2 (CLDN18.2)-redirected CAR T cells showed promising efficacy against gastric cancer (GC) in a preclinical study. Here we report the interim analysis results of an ongoing, open-label, single-arm, phase 1 clinical trial of CLDN18.2-targeted CAR T cells (CT041) in patients with previously treated, CLDN18.2-positive digestive system cancers ( NCT03874897 ). The primary objective was safety after CT041 infusion; secondary objectives included CT041 efficacy, pharmacokinetics and immunogenicity. We treated 37 patients with one of three CT041 doses: 2.5 × 108, 3.75 × 108 or 5.0 × 108 cells. All patients experienced a grade 3 or higher hematologic toxicity. Grade 1 or 2 cytokine release syndrome (CRS) occurred in 94.6% of patients. No grade 3 or higher CRS or neurotoxicities, treatment-related deaths or dose-limiting toxicities were reported. The overall response rate (ORR) and disease control rate (DCR) reached 48.6% and 73.0%, respectively. The 6-month duration of response rate was 44.8%. In patients with GC, the ORR and DCR reached 57.1% and 75.0%, respectively, and the 6-month overall survival rate was 81.2%. These initial results suggest that CT041 has promising efficacy with an acceptable safety profile in patients with heavily pretreated, CLDN18.2-positive digestive system cancers, particularly in those with GC.

Claudin18.2-specific CAR T cells in gastrointestinal cancers: phase 1 trial interim results

Despite success in hematologic malignancies, the treatment landscape of chimeric antigen receptor (CAR) T cell therapy for solid tumors remains limited. Claudin18.2 (CLDN18.2)-redirected CAR T cells showed promising efficacy against gastric cancer (GC) in a preclinical study. Here we report the interim analysis results of an ongoing, open-label, single-arm, phase 1 clinical trial of CLDN18.2-targeted CAR T cells (CT041) in patients with previously treated, CLDN18.2-positive digestive system cancers ( NCT03874897 ). The primary objective was safety after CT041 infusion; secondary objectives included CT041 efficacy, pharmacokinetics and immunogenicity. We treated 37 patients with one of three CT041 doses: 2.5 × 108, 3.75 × 108 or 5.0 × 108 cells. All patients experienced a grade 3 or higher hematologic toxicity. Grade 1 or 2 cytokine release syndrome (CRS) occurred in 94.6% of patients. No grade 3 or higher CRS or neurotoxicities, treatment-related deaths or dose-limiting toxicities were reported. The overall response rate (ORR) and disease control rate (DCR) reached 48.6% and 73.0%, respectively. The 6-month duration of response rate was 44.8%. In patients with GC, the ORR and DCR reached 57.1% and 75.0%, respectively, and the 6-month overall survival rate was 81.2%. These initial results suggest that CT041 has promising efficacy with an acceptable safety profile in patients with heavily pretreated, CLDN18.2-positive digestive system cancers, particularly in those with GC.

Claudin18.2-specific CAR T cells in gastrointestinal cancers: phase 1 trial interim results

Despite success in hematologic malignancies, the treatment landscape of chimeric antigen receptor (CAR) T cell therapy for solid tumors remains limited. Claudin18.2 (CLDN18.2)-redirected CAR T cells showed promising efficacy against gastric cancer (GC) in a preclinical study. Here we report the interim analysis results of an ongoing, open-label, single-arm, phase 1 clinical trial of CLDN18.2-targeted CAR T cells (CT041) in patients with previously treated, CLDN18.2-positive digestive system cancers ( NCT03874897 ). The primary objective was safety after CT041 infusion; secondary objectives included CT041 efficacy, pharmacokinetics and immunogenicity. We treated 37 patients with one of three CT041 doses: 2.5 × 108, 3.75 × 108 or 5.0 × 108 cells. All patients experienced a grade 3 or higher hematologic toxicity. Grade 1 or 2 cytokine release syndrome (CRS) occurred in 94.6% of patients. No grade 3 or higher CRS or neurotoxicities, treatment-related deaths or dose-limiting toxicities were reported. The overall response rate (ORR) and disease control rate (DCR) reached 48.6% and 73.0%, respectively. The 6-month duration of response rate was 44.8%. In patients with GC, the ORR and DCR reached 57.1% and 75.0%, respectively, and the 6-month overall survival rate was 81.2%. These initial results suggest that CT041 has promising efficacy with an acceptable safety profile in patients with heavily pretreated, CLDN18.2-positive digestive system cancers, particularly in those with GC.

Claudin18.2-specific CAR T cells in gastrointestinal cancers: phase 1 trial interim results

Despite success in hematologic malignancies, the treatment landscape of chimeric antigen receptor (CAR) T cell therapy for solid tumors remains limited. Claudin18.2 (CLDN18.2)-redirected CAR T cells showed promising efficacy against gastric cancer (GC) in a preclinical study. Here we report the interim analysis results of an ongoing, open-label, single-arm, phase 1 clinical trial of CLDN18.2-targeted CAR T cells (CT041) in patients with previously treated, CLDN18.2-positive digestive system cancers ( NCT03874897 ). The primary objective was safety after CT041 infusion; secondary objectives included CT041 efficacy, pharmacokinetics and immunogenicity. We treated 37 patients with one of three CT041 doses: 2.5 × 108, 3.75 × 108 or 5.0 × 108 cells. All patients experienced a grade 3 or higher hematologic toxicity. Grade 1 or 2 cytokine release syndrome (CRS) occurred in 94.6% of patients. No grade 3 or higher CRS or neurotoxicities, treatment-related deaths or dose-limiting toxicities were reported. The overall response rate (ORR) and disease control rate (DCR) reached 48.6% and 73.0%, respectively. The 6-month duration of response rate was 44.8%. In patients with GC, the ORR and DCR reached 57.1% and 75.0%, respectively, and the 6-month overall survival rate was 81.2%. These initial results suggest that CT041 has promising efficacy with an acceptable safety profile in patients with heavily pretreated, CLDN18.2-positive digestive system cancers, particularly in those with GC.

Claudin18.2-specific CAR T cells in gastrointestinal cancers: phase 1 trial interim results

Despite success in hematologic malignancies, the treatment landscape of chimeric antigen receptor (CAR) T cell therapy for solid tumors remains limited. Claudin18.2 (CLDN18.2)-redirected CAR T cells showed promising efficacy against gastric cancer (GC) in a preclinical study. Here we report the interim analysis results of an ongoing, open-label, single-arm, phase 1 clinical trial of CLDN18.2-targeted CAR T cells (CT041) in patients with previously treated, CLDN18.2-positive digestive system cancers ( NCT03874897 ). The primary objective was safety after CT041 infusion; secondary objectives included CT041 efficacy, pharmacokinetics and immunogenicity. We treated 37 patients with one of three CT041 doses: 2.5 × 108, 3.75 × 108 or 5.0 × 108 cells. All patients experienced a grade 3 or higher hematologic toxicity. Grade 1 or 2 cytokine release syndrome (CRS) occurred in 94.6% of patients. No grade 3 or higher CRS or neurotoxicities, treatment-related deaths or dose-limiting toxicities were reported. The overall response rate (ORR) and disease control rate (DCR) reached 48.6% and 73.0%, respectively. The 6-month duration of response rate was 44.8%. In patients with GC, the ORR and DCR reached 57.1% and 75.0%, respectively, and the 6-month overall survival rate was 81.2%. These initial results suggest that CT041 has promising efficacy with an acceptable safety profile in patients with heavily pretreated, CLDN18.2-positive digestive system cancers, particularly in those with GC.

Claudin18.2-specific CAR T cells in gastrointestinal cancers: phase 1 trial interim results

Despite success in hematologic malignancies, the treatment landscape of chimeric antigen receptor (CAR) T cell therapy for solid tumors remains limited. Claudin18.2 (CLDN18.2)-redirected CAR T cells showed promising efficacy against gastric cancer (GC) in a preclinical study. Here we report the interim analysis results of an ongoing, open-label, single-arm, phase 1 clinical trial of CLDN18.2-targeted CAR T cells (CT041) in patients with previously treated, CLDN18.2-positive digestive system cancers (NCT03874897). The primary objective was safety after CT041 infusion; secondary objectives included CT041 efficacy, pharmacokinetics and immunogenicity. We treated 37 patients with one of three CT041 doses: 2.5 × 10⁸, 3.75 × 10⁸ or 5.0 × 10⁸ cells. All patients experienced a grade 3 or higher hematologic toxicity. Grade 1 or 2 cytokine release syndrome (CRS) occurred in 94.6% of patients. No grade 3 or higher CRS or neurotoxicities, treatment-related deaths or dose-limiting toxicities were reported. The overall response rate (ORR) and disease control rate (DCR) reached 48.6% and 73.0%, respectively. The 6-month duration of response rate was 44.8%. In patients with GC, the ORR and DCR reached 57.1% and 75.0%, respectively, and the 6-month overall survival rate was 81.2%. These initial results suggest that CT041 has promising efficacy with an acceptable safety profile in patients with heavily pretreated, CLDN18.2-positive digestive system cancers, particularly in those with GC.

In an interim analysis of a phase 1 trial, CAR T cells specific for Claudin18.2, a tight junction protein isoform highly expressed on gastrointestinal tract tumors, were well-tolerated and exhibited promising clinical activity in patients with gastrointestinal cancers.

Prädiktive Immunzytochemie beim nicht-kleinzelligen Lungenkarzinom

Die Immunchemie ist eine zeit-, tumorproben- und kosteneffiziente Methode zur Untersuchung prädiktiver Biomarker bei fortgeschrittenen nicht-kleinzelligen Lungenkarzinomen (NSCLC). Die Immunhistochemie (IHC) an Formalin-fixiertem, Paraffin-eingebettetem (FFPE) Tumorgewebe hat sich für den Nachweis der PD-L1-Expression sowie für die ALK-, ROS1- und neuerdings auch für die NTRK-Untersuchung bewährt. Zytologische Proben als Quelle für prädiktive Markeranalysen sind sehr wichtig, da bis zu 40 % aller NSCLC rein zytologisch diagnostiziert werden.

Trotz der etablierten Rolle der Zytologie in der Lungenkarzinomdiagnostik wurden keine kommerziellen IHC-Assays für zytologische Proben validiert.

Die prädiktive Immunzytochemie (ICC) ist am einfachsten an FFPE-Zellblöcken (CB) durchzuführen, da für FFPE-Histologie standardisierte Protokolle verwendet werden können. CB sind jedoch nicht immer verfügbar.

Nicht als CB verarbeitete zytologische Präparate sind weniger standardisiert als histologische Präparate und weisen eine erhebliche präanalytische Variabilität auf. Daher ist eine strenge zytologiespezifische Optimierung, Validierung und Qualitätskontrolle von ICC-Protokollen erforderlich. Unter dieser Voraussetzung ist die prädiktive ICC, die in der Regel an Papanicolaou-gefärbten Zytologien durchgeführt wird, robust und zuverlässig. Dieses wertvolle zytologische Material sollte für prädiktive Biomarkeranalysen genutzt werden, um Patientinnen und Patienten nicht dem unnötigen Risiko einer erneuten Probenentnahme auszusetzen. Diese Übersichtsarbeit beleuchtet präanalytische, analytische und postanalytische Aspekte, die ICC-Ergebnisse beeinflussen können, und fasst die veröffentlichten Daten zur prädiktiven ICC für PD-L1, ALK und ROS1 bei NSCLC zusammen.

Program death ligand-1 immunocytochemistry in lung cancer cytological samples: A systematic review

In this era of personalized medicine, targeted immunotherapies like immune checkpoint inhibitors (ICI) blocking the programmed death‐1 (PD‐1)/program death ligand‐1 (PD‐L1) axis have become an integral part of treating advanced stage non‐small cell lung carcinoma (NSCLC) and many other cancer types. Multiple monoclonal antibodies are available commercially to detect PD‐L1 expression in tumor cells by immunohistochemistry (IHC). As most clinical trials initially required tumor biopsy for PD‐L1 detection by IHC, many of the currently available PD‐1/PD‐L1 assays have been developed and validated on formalin fixed tissue specimens. The majority (>50%) of lung cancer cases do not have a surgical biopsy or resection specimen available for ancillary testing and instead must rely primarily on fine needle aspiration biopsy specimens for diagnosis, staging and ancillary tests. Review of the literature shows multiple studies exploring the feasibility of PD‐L1 IHC on cytological samples. In addition, there are studies addressing various aspects of IHC validation on cytology preparations including pre‐analytical (e.g., different fixatives), analytical (e.g., antibody clone, staining platforms, inter and intra‐observer agreement, cytology‐histology concordance) and post‐analytical (e.g., clinical outcome) issues. Although promising results in this field have emerged utilizing cytology samples, many important questions still need to be addressed. This review summarizes the literature of PD‐L1 IHC in lung cytology specimens and provides practical tips for optimizing analysis.

Molecular diagnosis in non-small-cell lung cancer: expert opinion on ALK and ROS1 testing

The effectiveness of targeted therapies with tyrosine kinase inhibitors in non-small-cell lung cancer (NSCLC) depends on the accurate determination of the genomic status of the tumour. For this reason, molecular analyses to detect genetic rearrangements in some genes (ie, ALK, ROS1, RET and NTRK) have become standard in patients with advanced disease. Since immunohistochemistry is easier to implement and interpret, it is normally used as the screening procedure, while fluorescence in situ hybridisation (FISH) is used to confirm the rearrangement and decide on ambiguous immunostainings. Although FISH is considered the most sensitive method for the detection of ALK and ROS1 rearrangements, the interpretation of results requires detailed guidelines. In this review, we discuss the various technologies available to evaluate ALK and ROS1 genomic rearrangements using these techniques. Other techniques such as real-time PCR and next-generation sequencing have been developed recently to evaluate ALK and ROS1 gene rearrangements, but some limitations prevent their full implementation in the clinical setting. Similarly, liquid biopsies have the potential to change the treatment of patients with advanced lung cancer, but further research is required before this technology can be applied in routine clinical practice. We discuss the technical requirements of laboratories in the light of quality assurance programmes. Finally, we review the recent updates made to the guidelines for the determination of molecular biomarkers in patients with NSCLC.

Targeting immune checkpoints in gynecologic cancer: updates & perspectives for pathologists

Checkpoint inhibitor-based immunotherapy is increasingly used in the treatment of gynecologic cancers, and most often targets the PD-1/PD-L1 axis. Pathologists should be familiar with the biomarkers required to determine candidacy for these treatments based on existing FDA approvals, including mismatch repair protein immunohistochemistry, microsatellite instability testing, tumor mutation burden testing, and PD-L1 immunohistochemistry. This review summarizes the rationale behind these treatments and their associated biomarkers and delivers guidance on how to utilize and readout these tests. It also introduces additional biomarkers which may provide information regarding immunotherapeutic vulnerability in the future such as neoantigen load; POLE mutation status; and immunohistochemical expression of immunosuppressive checkpoints like LAG-3, TIM-3, TIGIT, and VISTA; immune-activating checkpoints such as CD27, CD40, CD134, and CD137; enzymes such as IDO-1 and adenosine-related compounds; and MHC class I.