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.

Genomic and Immunophenotypic Landscape of Acquired Resistance to PD-(L)1 Blockade in Non-Small-Cell Lung Cancer

PURPOSE

Although immune checkpoint inhibitors (ICI) have extended survival in patients with non-small-cell lung cancer (NSCLC), acquired resistance (AR) to ICI frequently develops after an initial benefit. However, the mechanisms of AR to ICI in NSCLC are largely unknown.

METHODS

Comprehensive tumor genomic profiling, machine learning-based assessment of tumor-infiltrating lymphocytes, multiplexed immunofluorescence, and/or HLA-I immunohistochemistry (IHC) were performed on matched pre- and post-ICI tumor biopsies from patients with NSCLC treated with ICI at the Dana-Farber Cancer Institute who developed AR to ICI. Two additional cohorts of patients with intervening chemotherapy or targeted therapies between biopsies were included as controls.

RESULTS

We performed comprehensive genomic profiling and immunophenotypic characterization on samples from 82 patients with NSCLC and matched pre- and post-ICI biopsies and compared findings with a control cohort of patients with non-ICI intervening therapies between biopsies (chemotherapy, N = 32; targeted therapies, N = 89; both, N = 17). Putative resistance mutations were identified in 27.8% of immunotherapy-treated cases and included acquired loss-of-function mutations in STK11, B2M, APC, MTOR, KEAP1, and JAK1/2; these acquired alterations were not observed in the control groups. Immunophenotyping of matched pre- and post-ICI samples demonstrated significant decreases in intratumoral lymphocytes, CD3e+ and CD8a+ T cells, and PD-L1-PD1 engagement, as well as increased distance between tumor cells and CD8+PD-1+ T cells. There was a significant decrease in HLA class I expression in the immunotherapy cohort at the time of AR compared with the chemotherapy (P = .005) and the targeted therapy (P = .01) cohorts.

CONCLUSION

These findings highlight the genomic and immunophenotypic heterogeneity of ICI resistance in NSCLC, which will need to be considered when developing novel therapeutic strategies aimed at overcoming resistance.

Validation of targeted next-generation sequencing of cell-free DNA from archival cerebrospinal fluid specimens for the detection of somatic variants in cancer involving the leptomeninges: Cytopathologic and radiographic correlation

BACKGROUND

Leptomeningeal metastases occur across multiple solid and lymphoid cancers, and patients typically undergo cytopathologic assessment of cerebrospinal fluid (CSF) in this setting. For patients diagnosed with metastatic cancer, the detection of actionable somatic mutations in CSF can provide clinically valuable information for treatment without the need for additional tissue collection.

METHODS

The authors validated a targeted next-generation sequencing assay for the detection of somatic variants in cancer (OncoPanel) on cell-free DNA (cfDNA) isolated from archival CSF specimens in a cohort of 25 patients who had undergone molecular testing of a prior tumor specimen.

RESULTS

CSF storage time and volume had no impact on cfDNA concentration or mean target coverage of the assay. Previously identified somatic variants in CSF cfDNA were detected in 88%, 50%, and 27% of specimens diagnosed cytologically as positive, suspicious/atypical, and negative for malignancy, respectively. Somatic variants were identified in 81% of CSF specimens from patients who had leptomeningeal enhancement on magnetic resonance imaging compared with 31% from patients without such enhancement.

CONCLUSIONS

These data highlight the stability of cfDNA in CSF, which allows for cytopathologic evaluation before triage for next-generation sequencing assays. For a subset of cases in which clinical suspicion is high but cytologic or radiographic studies are inconclusive, the detection of pathogenic somatic variants in CSF cfDNA may aid in the diagnosis of leptomeningeal metastases.

A Panel-Based Mutational Signature of Mismatch Repair Deficiency is Associated With Durable Response to Pembrolizumab in Metastatic Castration-Resistant Prostate Cancer

INTRODUCTION/BACKGROUND

Immune checkpoint inhibitors (ICIs) have limited efficacy in prostate cancer (PCa). Better biomarkers are needed to predict responses to ICIs. We sought to demonstrate that a panel-based mutational signature identifies mismatch repair (MMR) deficient (MMRd) PCa and is a biomarker of response to pembrolizumab.

PATIENTS AND METHODS

Clinico-genomic data was obtained for 2664 patients with PCa sequenced at Dana-Farber Cancer Institute (DFCI) and Memorial Sloan Kettering (MSK). Clinical outcomes were collected for patients with metastatic castration-resistant PCa (mCRPC) treated with pembrolizumab at DFCI. SigMA was used to characterize tumors as MMRd or MMR proficient (MMRp). The concordance between MMRd with microsatellite instability (MSI-H) was assessed. Radiographic progression-free survival (rPFS) and overall survival (OS) were collected for patients treated with pembrolizumab. Event-time distributions were estimated using Kaplan-Meier methodology.

RESULTS

Across both cohorts, 100% (DFCI: 12/12; MSK: 43/43) of MSI-H tumors were MMRd. However, 14% (2/14) and 9.1% (6/66) of MMRd tumors in the DFCI and MSK cohorts respectively were microsatellite stable (MSS), and 26% (17/66) were MSI-indeterminate in the MSK cohort. Among patients treated with pembrolizumab, those with MMRd (n = 5) versus MMRp (n = 14) mCRPC experienced markedly improved rPFS (HR = 0.088, 95% CI: 0.011-0.70; P = .0064) and OS (HR = 0.11, 95% CI: 0.014-0.80; P = .010) from start of treatment. Four patients with MMRd experienced remissions of >= 2.5 years.

CONCLUSION

SigMA detects additional cases of MMRd as compared to MSI testing in PCa and identifies patients likely to experience durable response to pembrolizumab.

Prognostic and predictive biomarkers in non-small cell lung carcinoma

Lung cancer is the most common cause of cancer-related deaths globally, with the highest mortality rates among both men and women. Most lung cancers are diagnosed at late stages, necessitating systemic therapy. Modern clinical management of lung cancer relies heavily upon application of biomarkers, which guide the selection of systemic treatment. Here, we provide an overview of currently approved and emerging biomarkers of non-small cell lung cancer (NSCLC), including EGFR, ALK, ROS1, RET, NTRK1-3, KRAS, BRAF, MET, ERBB2/HER2, NRG1, PD-L1, TROP2, and CEACAM5. For practical purposes, we divide these biomarkers into genomic and protein markers, based on the tested substrate. We review the biology and epidemiology of the genomic and proteomic biomarkers, discuss optimal diagnostic assays for their detection, and highlight their contribution to the contemporary clinical management of NSCLC.

Benchmarking mismatch repair testing for patients with cancer receiving immunotherapy

Immunohistochemistry (IHC) is currently the first-line test for mismatch repair deficiency (MMR-D). Bou Farhat et al. show that mismatch repair (MMR) mutation signature by next-generation sequencing is a highly sensitive assay capable of detecting MMR-D cases that are missed in 1% and 5% of patients with MMR-D colorectal cancer (CRC) and endometrial cancer (EC), respectively. Patients with MMR-D tumors missed by IHC have similar clinical outcomes to patients with MMR-D by both IHC and mutation signature.

Testicular Neoplasms With Sex Cord and Stromal Components Harbor a Recurrent Pattern of Chromosomal Gains

A small subset of testicular sex cord-stromal tumors, designated as Sertoli-stromal cell tumors (SSCTs), comprises a mixture of Sertoli, spindle, and/or Leydig cells. The clinicopathologic features of these tumors have not been studied in any detail, and their molecular features are unknown. We, therefore, assessed the morphologic and genomic features of 14 SSCTs, including 1 tumor with features similar to the ovarian Sertoli-Leydig cell tumor (SLCT) with retiform tubules. The median age of the patients was 24 years (range, 10-55 years), and the median tumor size was 2.3 cm (range, 0.7-4.7 cm). All tumors showed Sertoli-like sex cord cells arranged in variably developed tubular structures, typically also forming nests and cords. These imperceptibly blended with a neoplastic spindle cell stroma or, in the SLCT, vacuolated to eosinophilic Leydig cells. Genomic analysis demonstrated the presence of a hotspot loss-of-function DICER1 mutation in the SLCT (patient 1) and hotspot gain-of-function CTNNB1 mutations in the tumors of patients 2 and 3, with both CTNNB1 variants being interpreted as possible subclonal events. The mutations were the only relevant findings in the tumors of patients 1 and 2, whereas the tumor of patient 3 harbored concurrent chromosomal arm-level and chromosome-level copy number gains. Among the remaining 11 tumors, all of those that had interpretable copy number data (9 tumors) harbored multiple recurrent chromosomal arm-level and chromosome-level copy number gains suggestive of a shift in ploidy without concurrent pathogenic mutations. The results of the present study suggest that CTNNB1 mutations (likely subclonal) are only rarely present in SSCTs; instead, most of them harbor genomic alterations similar to those seen in testicular sex cord-stromal tumors with pure or predominant spindle cell components. A notable exception was a testicular SLCT with morphologic features identical to the ovarian counterpart, which harbored a DICER1 mutation.

Genomic analysis of spermatocytic tumors demonstrates recurrent molecular alterations in cases with malignant clinical behavior

Spermatocytic tumor (ST) is a rare type of germ cell tumor that occurs exclusively in the postpubertal testis and typically affects elderly men. Most STs are benign, but rare cases exhibit aggressive clinical behavior, often in association with transition to sarcomatoid histology. Limited molecular analyses have been performed on STs; therefore, their genomic and epigenomic features remain incompletely described. Twenty-seven samples from 25 individual patients were analyzed with a combination of DNA sequencing panels, genomic methylation profiling, SNP array, isochromosome (12p) [i(12p)] FISH, and immunohistochemistry. The series included five metastasizing tumors (three with sarcomatoid transformation, one anaplastic, and one conventional) and 20 non-metastasizing tumors (14 anaplastic and six conventional). Anaplastic tumors comprised a monomorphic population of intermediate-sized neoplastic cells, as previously described. Multiomic analyses demonstrated that there were two genomic subgroups of STs: one with diploid genomes and hotspot RAS/RAF variants and the other with global ploidy shift and absence of recurrent mutations. Relative gain of chromosome 9 was a consistent finding in both subgroups. A comparison of metastasizing and non-metastasizing cases demonstrated that aggressive behavior was associated with the acquisition of pathogenic TP53 mutations and/or relative gains of 12p/i(12p). In cases with sarcomatoid transformation, TP53 mutations seem to underlie the transition to sarcomatoid histology. Genomic methylation analysis demonstrated that aggressive cases with gains of 12p cluster closer to pure seminomas than to STs without gains of 12p. In conclusion, STs include two genomic subgroups, characterized by global ploidy shifts without recurrent mutations and diploid genomes with RAS/RAF hotspot mutations, respectively. Biologic progression was associated with relative gains of 12p and TP53 mutations. The findings in STs with relative gains of 12p suggest that they may exhibit biologic characteristics akin to those seen in germ cell neoplasia in situ-related germ cell tumors rather than non-germ cell neoplasia in situ-derived STs. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Initial Chemotherapy for Locally Advanced and Metastatic NUT Carcinoma

INTRODUCTION

NUT carcinoma (NC) is an underdiagnosed and aggressive poorly differentiated or squamous cell cancer. A subset of NC is sensitive to chemotherapy, but the optimal regimen is unknown. Experts have recommended platinum- and ifosfamide-based therapy based on case reports.

METHODS

Patients with pathologically confirmed NC with known survival outcomes after chemotherapy and consented to participate in a worldwide registry were studied. Results were summarized using descriptive methods.

RESULTS

The study included 118 patients with NC. Median age was 34 (range: 1-82) years, 39% were women, and 61% harbored a BRD4::NUTM1 fusion. Patients received platinum (74%) or ifosfamide (26%, including regimens with both, 13%). Of 62 patients with nonmetastatic disease, 40% had a thoracic primary. Compared with platinum-based chemotherapy, patients who received ifosfamide-based chemotherapy had nominally higher progression-free survival (12 mo: 59% [95% CI: 32-87] versus 37% [95% CI: 22-52], hazard ratio = 0.68 [0.32, 1.42], p = 0.3) but not overall survival (OS). Among the 56 patients with metastatic disease, 80% had a thoracic primary. Ifosfamide had an objective response rate (ORR) of 75% (six of eight) and platinum had an ORR of 31% (11 of 36). Nevertheless, there was no difference in progression-free survival or OS. The 3-year OS of the entire cohort was 19% (95% CI: 10%-28%). Of the 11 patients alive greater than 3 years, all presented with nonmetastatic and operable or resectable disease.

CONCLUSION

There is a numerically higher ORR for ifosfamide-based therapy compared with platinum-based therapy, with limited durability. OS at 3 years is only 19%, and development of effective therapies is an urgent unmet need for this patient population.

Prevalence and Therapeutic Targeting of High-Level ERBB2 Amplification in NSCLC

INTRODUCTION

ERBB2 amplification in lung cancer remains poorly characterized. HER2 (encoded by ERBB2) is a transmembrane tyrosine kinase capable of ligand-independent dimerization and signaling when overexpressed, and a common cause of HER2 overexpression is ERBB2 amplification. Here, we evaluated the clinicopathologic and genomic characteristics of ERBB2-amplified NSCLC and explored a HER2 antibody-drug conjugate (ADC) therapeutic strategy.

METHODS

Our institutional next-generation DNA sequencing data (OncoPanel) from 5769 NSCLC samples (5075 patients) were queried for cases having high-level ERBB2 amplification (≥6 copies). Clinical and demographic characteristics were extracted from the electronic medical records. Efficacy of the pan-ERBB inhibitor afatinib or HER2 ADCs (trastuzumab deruxtecan and trastuzumab emtansine) was evaluated in NSCLC preclinical models and patients with ERBB2 amplification.

RESULTS

High-level ERBB2 amplification was identified in 0.9% of lung adenocarcinomas and reliably predicted overexpression of HER2. ERBB2 amplification events are detected in two distinct clinicopathologic and genomic subsets of NSCLC: as the sole mitogenic driver in tumors arising in patients with a smoking history or as a concomitant alteration with other mitogenic drivers in patients with a light or never smoking history. We further reveal that trastuzumab deruxtecan is effective therapy in in vitro and in vivo preclinical models of NSCLC harboring ERBB2 amplification and report two cases of clinical activity of an anti-HER2 ADC in patients who acquired ERBB2 amplification after previous targeted therapy.

CONCLUSIONS

High-level ERBB2 amplification reliably predicts HER2 overexpression in patients with NSCLC, and HER2 ADC is effective therapy in this population.

PAX1 expression in thymic epithelial neoplasms and morphologic mimics

Thymic epithelial neoplasms are morphologically diverse and can pose a diagnostic challenge that is complicated by a lack of immunohistochemistry (IHC) markers that are entirely sensitive and specific for thymic epithelium. Polyclonal PAX8 is often used in this context, but it is not a specific marker. The PAX1 transcription factor shares significant homology with PAX8 and plays an integral role in thymic development in humans and murine models. This study evaluated the role of PAX1 IHC in differentiating thymic epithelial neoplasms from morphologic mimics on whole slide tissue sections. The PAX1 antibody stained all 74 thymoma cases; however, there was wide variability in staining intensity within each subtype. The antibody was less sensitive in thymic carcinomas and thymic neuroendocrine tumors compared to thymomas and demonstrated weak staining in a subset of morphologic mimics (21 squamous cell carcinomas, 6 pulmonary neuroendocrine tumors, 1 mesothelioma, 1 lymphoblastic lymphoma, and 1 granulosa cell tumor). With a H-score positive threshold of 75, the antibody had 100% specificity, and sensitivities of 92%, 56%, and 47% in thymomas, thymic neuroendocrine tumors, and thymic carcinomas respectively. The PAX1 antibody showed frequent geographic reduction in staining consistent with compromised antigenicity from variable formalin fixation. PAX1 IHC has a moderate-to-high sensitivity for thymic epithelial neoplasms; however, the wide staining variability and fixation effects may lead to difficulty with consistent interpretation. This marker is unlikely to supplant the role of PAX8 in diagnostic practice, but it may be a useful addition to immunohistochemistry panels when evaluating for thymic primary tumors.

Activation of CD8+ T Cells in Chronic Obstructive Pulmonary Disease Lung

Rationale: Despite the importance of inflammation in chronic obstructive pulmonary disease (COPD), the immune cell landscape in the lung tissue of patients with mild-moderate disease has not been well characterized at the single-cell and molecular level. Objectives: To define the immune cell landscape in lung tissue from patients with mild-moderate COPD at single-cell resolution. Methods: We performed single-cell transcriptomic, proteomic, and T-cell receptor repertoire analyses on lung tissue from patients with mild-moderate COPD (n = 5, Global Initiative for Chronic Obstructive Lung Disease I or II), emphysema without airflow obstruction (n = 5), end-stage COPD (n = 2), control (n = 6), or donors (n = 4). We validated in an independent patient cohort (N = 929) and integrated with the Hhip+/- murine model of COPD. Measurements and Main Results: Mild-moderate COPD lungs have increased abundance of two CD8+ T cell subpopulations: cytotoxic KLRG1+TIGIT+CX3CR1+ TEMRA (T effector memory CD45RA+) cells, and DNAM-1+CCR5+ T resident memory (TRM) cells. These CD8+ T cells interact with myeloid and alveolar type II cells via IFNG and have hyperexpanded T-cell receptor clonotypes. In an independent cohort, the CD8+KLRG1+ TEMRA cells are increased in mild-moderate COPD lung compared with control or end-stage COPD lung. Human CD8+KLRG1+ TEMRA cells are similar to CD8+ T cells driving inflammation in an aging-related murine model of COPD. Conclusions: CD8+ TEMRA cells are increased in mild-moderate COPD lung and may contribute to inflammation that precedes severe disease. Further study of these CD8+ T cells may have therapeutic implications for preventing severe COPD.

Germline EGFR Mutations and Familial Lung Cancer

PURPOSE

The genomic underpinnings of inherited lung cancer risk are poorly understood. This prospective study characterized the clinical phenotype of patients and families with germline EGFR pathogenic variants (PVs).

METHODS

The Investigating Hereditary Risk from T790M study (ClinicalTrials.gov identifier: NCT01754025) enrolled patients with lung cancer whose tumor profiling harbored possible germline EGFR PVs and their relatives, either in person or remotely, providing germline testing and follow-up.

RESULTS

A total of 141 participants were enrolled over a 5-year period, 100 (71%) remotely. Based upon previous genotyping, 116 participants from 59 kindreds were tested for EGFR T790M, demonstrating a pattern of Mendelian inheritance with variable lung cancer penetrance. In confirmed or obligate carriers of a germline EGFR PV from 39 different kindreds, 50/91 (55%) were affected with lung cancer with 34/65 (52%) diagnosed by age 60 years. Somatic testing of lung cancers in carriers revealed that 35 of 37 (95%) had an EGFR driver comutation. Among 36 germline carriers without a cancer diagnosis, 15 had computed tomography (CT) imaging and nine had lung nodules, including a 28-year-old with >10 lung nodules. Given geographic enrichment of germline EGFR T790M in the southeast United States, genome-wide haplotyping of 46 germline carriers was performed and identified a 4.1-Mb haplotype shared by 41 (89%), estimated to originate 223-279 years ago.

CONCLUSION

To our knowledge, this is the first prospective description of familial EGFR-mutant lung cancer, identifying a recent founder germline EGFR T790M variant enriched in the Southeast United States. The high prevalence of EGFR-driver lung adenocarcinomas and lung nodules in germline carriers supports effort to identify affected patients and family members for investigation of CT-based screening for these high-risk individuals.

Impact of Aneuploidy and Chromosome 9p Loss on Tumor Immune Microenvironment and Immune Checkpoint Inhibitor Efficacy in NSCLC

INTRODUCTION

Although gene-level copy number alterations have been studied as a potential biomarker of immunotherapy efficacy in NSCLC, the impact of aneuploidy burden and chromosomal arm-level events on immune checkpoint inhibitor (ICI) efficacy in NSCLC is uncertain.

METHODS

Patients who received programmed cell death protein 1 or programmed death-ligand 1 (PD-L1) inhibitor at two academic centers were included. Across all 22 chromosomes analyzed, an arm was considered altered if at least 70% of its territory was either gained or deleted. Among nonsquamous NSCLCs which underwent targeted next-generation sequencing, we retrospectively quantified aneuploidy using the adjusted fraction of chromosomal arm alterations (FAA), defined as the number of altered chromosome arms divided by the number of chromosome arms assessed, adjusted for tumor purity.

RESULTS

Among 2293 nonsquamous NSCLCs identified, the median FAA increased with more advanced cancer stage and decreased with higher PD-L1 tumor proportion score (TPS) levels (median FAA in TPS < 1%: 0.09, TPS 1%-49%: 0.08, TPS ≥ 50%: 0.05, p < 0.0001). There was a very weak correlation between FAA and tumor mutational burden when taken as continuous variables (R: 0.07, p = 0.0005). A total of 765 advanced nonsquamous NSCLCs with available FAA values were treated with ICIs. With decreasing FAA tertiles, there was a progressive improvement in objective response rate (ORR 15.1% in upper tertile versus 23.2% in middle tertile versus 28.4% in lowest tertile, p = 0.001), median progression-free survival (mPFS 2.5 versus 3.3 versus 4.1 mo, p < 0.0001), and median overall survival (mOS 12.5 versus 13.9 versus 16.4 mo, p = 0.006), respectively. In the arm-level enrichment analysis, chromosome 9p loss (OR = 0.22, Q = 0.0002) and chromosome 1q gain (OR = 0.43, Q = 0.002) were significantly enriched in ICI nonresponders after false discovery rate adjustment. Compared with NSCLCs without chromosome 9p loss (n = 452), those with 9p loss (n = 154) had a lower ORR (28.1% versus 7.8%, p < 0.0001), a shorter mPFS (4.1 versus 2.3 mo, p < 0.0001), and a shorter mOS (18.0 versus 9.6 mo, p < 0.0001) to immunotherapy. In addition, among NSCLCs with high PD-L1 expression (TPS ≥ 50%), chromosome 9p loss was associated with lower ORR (43% versus 6%, p < 0.0001), shorter mPFS (6.4 versus 2.6 mo, p = 0.0006), and shorter mOS (30.2 versus 14.3 mo, p = 0.0008) to immunotherapy compared with NSCLCs without 9p loss. In multivariable analysis, adjusting for key variables including FAA, chromosome 9p loss, but not 1q gain, retained a significant impact on ORR (hazard ratio [HR] = 0.25, p < 0.001), mPFS (HR = 1.49, p = 0.001), and mOS (HR = 1.47, p = 0.003). Multiplexed immunofluorescence and computational deconvolution of RNA sequencing data revealed that tumors with either high FAA levels or chromosome 9p loss had significantly fewer tumor-associated cytotoxic immune cells.

CONCLUSIONS

Nonsquamous NSCLCs with high aneuploidy and chromosome 9p loss have a distinct tumor immune microenvironment and less favorable outcomes to ICIs.

Analysis of recurrence in lung adenocarcinoma with spread through air spaces

OBJECTIVES

Spread through air spaces is defined as tumor cells in air spaces away from the edge of tumor in lung carcinoma. It is associated with higher locoregional recurrence and lower survival in lung adenocarcinoma. The features of spread through air spaces portending worse outcomes are still under investigation. We reviewed our lung cancer experience to define potential factors related to spread through air spaces that influence recurrence and survival.

METHODS

Between January 2010 and December 2017, we identified 968 patients who underwent resection for T1-3N0M0 lung adenocarcinoma. Of these, histologic examination was possible in 787 patients. We examined the presence of spread through air spaces, spread through air spaces characteristics (micropapillary, solid nest, or single cell), average density (number per slide), and farthest distance from tumor at which spread through air spaces was detected, or maximal spread distance. Overall survival and recurrence-free survival were estimated using Kaplan-Meier curves, and differences between spread through air spaces positive versus spread through air spaces negative groups were assessed using the log-rank test.

RESULTS

Spread through air spaces was present in 389 of 787 of the reviewed cases (49.4%). Overall survival and recurrence-free survival were significantly lower in the spread through air spaces positive group over 10 years (P < .0001). The incidences of locoregional and distant recurrence were nearly doubled over 10 years in the spread through air spaces positive group compared with the spread through air spaces negative group (P = .002 and <.0001, respectively). In a multivariable Cox regression model adjusted for spread through air spaces characteristics, distance, and tumor size, lobar resection did not confer survival advantage in patients with spread through air spaces (hazard ratio of sublobar resection with respect to lobar resection, 1.44; 95% confidence interval, 0.98-2.11; P = .067). In the spread through air spaces positive group, spread through air spaces density was 2.7 ± 1.4 clusters per slide and the maximal spread distance was 2.2 ± 1.7 mm from the tumor edge. There was no observed correlation between spread through air spaces density or maximal spread distance and overall survival or recurrence.

CONCLUSIONS

We show increased distant recurrence in spread through air spaces positive lung adenocarcinoma. Quantifiable measures of spread through air spaces do not appear to correlate with recurrence or survival metrics.

Recurrent Tumor Suppressor Alterations in Primary Pericardial Mesothelioma

Primary pericardial mesotheliomas are extremely rare, accounting for <1% of all mesotheliomas, and their molecular genetic features and predisposing factors remain to be determined. Here, we report the clinicopathologic, immunohistochemical, and molecular genetic findings of 3 pericardial mesotheliomas without pleural involvement. Three cases diagnosed between 2004 and 2022 were included in the study and analyzed by immunohistochemistry and targeted next-generation sequencing (NGS); corresponding nonneoplastic tissue was sequenced in all cases. Two patients were female and 1 was male, aged between 66 and 75 years. Two patients each had prior asbestos exposure and were smokers. Histologic subtypes were epithelioid in 2 cases and biphasic in 1 case. Immunohistochemical staining identified expression of cytokeratin AE1/AE3 and calretinin in all cases, D2-40 in 2 cases, and WT1 in 1 case. Staining for tumor suppressors revealed loss of p16, MTAP, and Merlin (NF2) expression in 2 cases and loss of BAP1 and p53 in 1 case. Abnormal cytoplasmic BAP1 expression was observed in an additional case. Protein expression abnormalities correlated with NGS results, which showed concurrent complete genomic inactivation of CDKN2A/p16, CDKN2B, MTAP, and NF2 in 2 mesotheliomas and of BAP1 and TP53 in 1 mesothelioma each, respectively. In addition, 1 patient harbored a pathogenic BRCA1 germline mutation, which resulted in biallelic inactivation in the mesothelioma. All mesotheliomas were mismatch repair proficient and showed several chromosomal gains and losses. All patients died from disease. Our study demonstrates that pericardial mesotheliomas share common morphologic, immunohistochemical, and molecular genetic features with pleural mesothelioma, including recurrent genomic inactivation of canonical tumor suppressors. Our study adds new insights into the genetic landscape of primary pericardial mesothelioma and highlights BRCA1 loss as a potential contributing factor in a subset of cases, thereby contributing to refined precision diagnostics for this rare cancer.

Atypical Droplet Digital Polymerase Chain Reaction Patterns That Indicate Uncommon but Clinically Actionable EGFR Mutations in Lung Cancer

CONTEXT.—

Droplet digital polymerase chain reaction (ddPCR) is a sensitive method to detect common pathogenic EGFR mutations in non-small cell lung cancer. Although targeted assays have not been specifically designed to detect them, uncommon EGFR mutations have been linked to response to targeted therapy.

OBJECTIVE.—

To describe atypical ddPCR patterns that correspond to uncommon but clinically actionable EGFR mutations.

DESIGN.—

A cohort of 1134 consecutive non-small cell lung cancers that underwent targeted next-generation sequencing was reviewed. Uncommon EGFR mutations involving probe binding sites were evaluated by ddPCR.

RESULTS.—

Two hundred fifty-five of 1134 cancers (22.5%) harbored pathogenic EGFR mutations. One hundred eighty-six of 255 (72.9%) had canonical EGFR exon 19 deletion or exon 21 p.L858R variants designed for detection by ddPCR. An additional 25 of 255 cases (9.8%) had uncommon EGFR mutations within the probe-binding site, including one case with concurrent uncommon mutations in both exon 19 and exon 21. These mutations included uncommon EGFR exon 19 deletions (n = 6), EGFR exon 19 substitutions p.L747P (n = 3) and p.L747A (n = 1), dinucleotide substitutions leading to EGFR p.L858R (n = 5), EGFR exon 21 substitutions p.K860I (n = 1) and p.L861Q (n = 9), and EGFR p.[L858R;K860I] (n = 1). Droplet digital polymerase chain reaction generated atypical but reproducible signal for each of these uncommon variants.

CONCLUSIONS.—

Droplet digital polymerase chain reaction analysis of uncommon pathogenic EGFR variants can yield unique and reproducible results. Recognition of atypical patterns in EGFR ddPCR testing can prompt confirmatory molecular testing and aid appropriate targeted therapy selection for patients with non-small cell lung cancer.

Machine learning for genetics-based classification and treatment response prediction in cancer of unknown primary

Cancer of unknown primary (CUP) is a type of cancer that cannot be traced back to its primary site and accounts for 3-5% of all cancers. Established targeted therapies are lacking for CUP, leading to generally poor outcomes. We developed OncoNPC, a machine-learning classifier trained on targeted next-generation sequencing (NGS) data from 36,445 tumors across 22 cancer types from three institutions. Oncology NGS-based primary cancer-type classifier (OncoNPC) achieved a weighted F1 score of 0.942 for high confidence predictions ([Formula: see text]) on held-out tumor samples, which made up 65.2% of all the held-out samples. When applied to 971 CUP tumors collected at the Dana-Farber Cancer Institute, OncoNPC predicted primary cancer types with high confidence in 41.2% of the tumors. OncoNPC also identified CUP subgroups with significantly higher polygenic germline risk for the predicted cancer types and with significantly different survival outcomes. Notably, patients with CUP who received first palliative intent treatments concordant with their OncoNPC-predicted cancers had significantly better outcomes (hazard ratio (HR) = 0.348; 95% confidence interval (CI) = 0.210-0.570; P = [Formula: see text]). Furthermore, OncoNPC enabled a 2.2-fold increase in patients with CUP who could have received genomically guided therapies. OncoNPC thus provides evidence of distinct CUP subgroups and offers the potential for clinical decision support for managing patients with CUP.

Clinicopathologic, Genomic, and Immunophenotypic Landscape of ATM Mutations in Non-Small Cell Lung Cancer

PURPOSE

ATM is the most commonly mutated DNA damage and repair gene in non-small cell lung cancer (NSCLC); however, limited characterization has been pursued.

EXPERIMENTAL DESIGN

Clinicopathologic, genomic, and treatment data were collected for 5,172 patients with NSCLC tumors which underwent genomic profiling. ATM IHC was performed on 182 NSCLCs with ATM mutations. Multiplexed immunofluorescence was performed on a subset of 535 samples to examine tumor-infiltrating immune cell subsets.

RESULTS

A total of 562 deleterious ATM mutations were identified in 9.7% of NSCLC samples. ATM-mutant (ATMMUT) NSCLC was significantly associated with female sex (P = 0.02), ever smoking status (P < 0.001), non-squamous histology (P = 0.004), and higher tumor mutational burden (DFCI, P < 0.0001; MSK, P < 0.0001) compared with ATM-wild-type (ATMWT) cases. Among 3,687 NSCLCs with comprehensive genomic profiling, co-occurring KRAS, STK11, and ARID2 oncogenic mutations were significantly enriched among ATMMUT NSCLCs (Q < 0.05), while TP53 and EGFR mutations were enriched in ATMWT NSCLCs. Among 182 ATMMUT samples with ATM IHC, tumors with nonsense, insertions/deletions, or splice site mutations were significantly more likely to display ATM loss by IHC (71.4% vs. 28.6%; P < 0.0001) compared with tumors with only predicted pathogenic missense mutations. Clinical outcomes to PD-(L)1 monotherapy (N = 1,522) and chemo-immunotherapy (N = 951) were similar between ATMMUT and ATMWT NSCLCs. Patients with concurrent ATM/TP53 mutations had significantly improved response rate and progression-free survival with PD-(L)1 monotherapy.

CONCLUSIONS

Deleterious ATM mutations defined a subset of NSCLC with unique clinicopathologic, genomic, and immunophenotypic features. Our data may serve as resource to guide interpretation of specific ATM mutations in NSCLC.

Molecular markers of metastatic disease in KRAS-mutant lung adenocarcinoma

BACKGROUND

Prior studies characterized the association of molecular alterations with treatment-specific outcomes in KRAS-mutant (KRASMUT) lung adenocarcinoma (LUAD). Less is known about the prognostic role of molecular alterations and their associations with metastatic disease.

PATIENTS AND METHODS

We analyzed clinicogenomic data from 1817 patients with KRASMUT LUAD sequenced at the Dana-Farber Cancer Institute (DFCI) and Memorial Sloan Kettering Cancer Center (MSKCC). Patients with metastatic (M1) and nonmetastatic (M0) disease were compared. Transcriptomic data from The Cancer Genome Atlas (TCGA) were investigated to characterize the biology of differential associations with clinical outcomes. Organ-specific metastasis was associated with overall survival (OS).

RESULTS

KEAP1 (DFCI: OR = 2.3, q = 0.04; MSKCC: OR = 2.2, q = 0.00027) and SMARCA4 mutations (DFCI: OR = 2.5, q = 0.06; MSKCC: OR = 2.6, q = 0.0021) were enriched in M1 versus M0 tumors. On integrative modeling, NRF2 activation was the genomic feature most associated with OS. KEAP1 mutations were enriched in M1 versus M0 tumors independent of STK11 status (KEAP1MUT/STK11WT: DFCI OR = 3.0, P = 0.0064; MSKCC OR = 2.0, P = 0.041; KEAP1MUT/STK11MUT: DFCI OR = 2.3, P = 0.0063; MSKCC OR = 2.5, P = 3.6 × 10-05); STK11 mutations without KEAP1 loss were not associated with stage (KEAP1WT/STK11MUT: DFCI OR = 0.97, P = 1.0; MSKCC OR = 1.2, P = 0.33) or outcome. KEAP1/KRAS-mutated tumors with and without STK11 mutations exhibited high functional STK11 loss. The negative effects of KEAP1 were compounded in the presence of bone (HR = 2.3, P = 4.4 × 10-14) and negated in the presence of lymph node metastasis (HR = 1.0, P = 0.91).

CONCLUSIONS

Mutations in KEAP1 and SMARCA4, but not STK11, were associated with metastatic disease and poor OS. Functional STK11 loss, however, may contribute to poor outcomes in KEAP1MUT tumors. Integrating molecular data with clinical and metastatic-site annotations can more accurately risk stratify patients.

Testicular Juvenile Granulosa Cell Tumors Demonstrate Recurrent Loss of Chromosome 10 and Absence of Molecular Alterations Described in Ovarian Counterparts

Testicular juvenile granulosa cell tumors (JGCTs) are a rare type of sex cord-stromal tumor, accounting for <5% of all neoplasms of the prepubertal testis. Previous reports have demonstrated sex chromosome anomalies in a small subset of cases, but the molecular alterations associated with JGCTs remain largely undescribed. We evaluated 18 JGCTs using massive parallel DNA and RNA sequencing panels. The median patient age was <1 month (range, newborn to 5 months). The patients presented with scrotal or intra-abdominal masses/enlargement, and all underwent radical orchiectomy (17 unilateral and 1 bilateral). The median tumor size was 1.8 cm (range, 1.3-10.5 cm). Histologically, the tumors were purely cystic/follicular or mixed (ie, solid and cystic/follicular). All cases were predominantly epithelioid, with 2 exhibiting prominent spindle cell components. Nuclear atypia was mild or absent, and the median number of mitoses was 0.4/mm2 (range, 0-10/mm2). Tumors frequently expressed SF-1 (11/12 cases, 92%), inhibin (6/7 cases, 86%), calretinin (3/4 cases, 75%), and keratins (2/4 cases, 50%). Single-nucleotide variant analysis demonstrated the absence of recurrent mutations. RNA sequencing did not detect gene fusions in 3 cases that were sequenced successfully. Recurrent monosomy 10 was identified in 8 of 14 cases (57%) with interpretable copy number variant data, and multiple whole-chromosome gains were present in the 2 cases with significant spindle cell components. This study demonstrated that testicular JGCTs harbor recurrent loss of chromosome 10 and lack the GNAS and AKT1 variants described in their ovarian counterparts.

Case Report: Complete pathologic response to neoadjuvant selpercatinib in a patient with resectable early-stage RET fusion-positive non-small cell lung cancer

The LIBRETTO-001 trial demonstrated the activity of the selective rearrangement during transfection (RET) inhibitor selpercatinib in advanced RET fusion-positive non-small cell lung cancer (NSCLC) and resulted in the drug's approval for this indication. A cohort that included neoadjuvant and adjuvant selpercatinib was opened on LIBRETTO-001 for early-stage RET fusion-positive NSCLC with the primary endpoint of major pathologic response. A patient with a stage IB (cT2aN0M0) KIF5B-RET fusion-positive NSCLC received 8 weeks of neoadjuvant selpercatinib at 160 mg twice daily followed by surgery. While moderate regression in the primary tumor (stable disease, Response Evaluation Criteria in Solid Tumors (RECIST) guidelines version 1.1) was observed radiologically, assessment via an Independent Pathologic Review Committee revealed a pathologic complete response (0% viable tumor). This consensus assessment by three independent pathologists was aided by RET fluorescence in situ hybridization testing of a reactive pneumocyte proliferation showing no rearrangement. Neoadjuvant selpercatinib was well-tolerated with only low-grade treatment-emergent adverse events. The activity of prospective preoperative selpercatinib in this case establishes proof of concept of the potential utility of RET inhibitor therapy in early-stage RET fusion-positive NSCLC.

Abstract 5706: ImmunoPROFILE: A prospective implementation of clinically validated, quantitative immune cell profiling test identifies tumor-infiltrating CD8+ and PD-1+ cell densities as prognostic biomarkers across a 2,023 patient pan-cancer cohort treated with different therapies

Tumor-infiltrating lymphocyte (TIL) density has been identified as a prognostic and predictive biomarker in select tumors treated with defined therapies. These observations suggest that TILs may be general markers of patient outcomes, but evidence in support of this hypothesis has been limited by small cohorts.

We validated ImmunoPROFILE, a multiplexed immunofluorescence (MIF)-based assay coupled with machine-learning-based image analysis, to identify and quantify tumor cells (cytokeratin, PAX5, PAX8, SOX10), T cells (CD8), T-regulatory cells (FOXP3), exhausted cells (PD-1) and immunosuppressive tumor and immune cells (PD-L1). We applied the MIF panel to specimens from patients collected prospectively over three years and analyzed 2,023 cases across 27 tumor types. The association between biomarkers and overall survival (OS) was investigated using Cox models controlling for patient risk factors such as cancer type, metastatic vs. primary disease, age, and gender. Multivariable biomarker selection was based on likelihood ratios.

The assay was highly robust (success rate 97%), reproducible (inter-scanning and intra-staining density controls within 1 SD, inter-staining PD-L1 scores ≤11% CV), and operator-independent (R2 &gt;0.7 to &gt;0.9 for each biomarker and 95% concordance in PD-L1 score-based interpretation between technicians). From whole slide images, a total of 11,932 individual regions of interest were analyzed across the cohort, resulting in &gt;50 million spatially-resolved single cells which were summarized into cell population densities and PD-L1 scores.

High densities of CD8+ (&gt;64/mm2, p&lt;0.0001), PD-1+ (&gt;50/mm2, p&lt;0.0001), and FOXP3+ (&gt;30/mm2, p&lt;0.0001) T cells were associated with longer overall survival (OS) irrespective of therapy and across all cancer types. PD-L1 metrics were not associated with OS (p=0.43). Compared to patients with low densities of CD8+ and PD-1+ cells, high densities of at least one of these cell types had better OS (Both high, HR: 0.49, 95% CI: 0.41 - 0.59; CD8+ high, HR: 0.63, (0.48 - 0.82); PD-1+ high, HR: 0.71, (0.54 - 0.93)). The results were consistent in the subset of patients (N=1572) who did not receive immunotherapy (IO). In patients who received IO therapy (N=451), only PD-1+ T-cell density associated with OS (HR: 0.48, (0.36 - 0.65)).

To our knowledge, this is the first enterprise-level immune biomarker assay using multiplexed staining, digital imaging, and machine learning to be applied in a prospective manner to clinical specimens at scale. We found that select immune cell densities are prognostic across cancer types and therapies and demonstrated that quantification of multiple cell populations yields better prognostic power than single marker analyses.

Citation Format: James Lindsay, Bijaya Sharma, Kristen D. Felt, Anita Giobbie-Hurder, Ian Dryg, Jason L. Weirather, Jennifer Altreuter, Tali Mazor, Priti Kumari, Joao V. Alessi, Ajit J. Nirmal, Michael P. Manos, Ananth R. Kumar, William Lotter, Ethan Cerami, Burce E. Johnson, Neil I. Lindeman, Lynette M. Sholl, Jonathan A. Nowak, Scott J. Rodig. ImmunoPROFILE: A prospective implementation of clinically validated, quantitative immune cell profiling test identifies tumor-infiltrating CD8+ and PD-1+ cell densities as prognostic biomarkers across a 2,023 patient pan-cancer cohort treated with different therapies. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5706.

Inflammatory and Nested Testicular Sex Cord Tumor: A Novel Neoplasm With Aggressive Clinical Behavior and Frequent EWSR1::ATF1 Gene Fusions

A subset of malignant testicular sex cord tumors (TSCTs), heretofore interpreted as Sertoli cell tumors, not otherwise specified, exhibits distinctive morphologic features that partially overlap with those of seminoma. In this study, we evaluated the clinicopathologic and molecular characteristics of 13 such tumors. The patients were 20 to 73 years old (median, 36 y), and all with available data presented with testicular masses (median size, 3 cm), with 2 having synchronous retroperitoneal metastases. All 11 patients with available follow-up developed metastases to retroperitoneal lymph nodes, nonretroperitoneal lymph nodes, bone, contralateral testis, and/or lung. Microscopically, the tumors showed solid nests and sheets of epithelioid cells with granular, eosinophilic to clear/vacuolated cytoplasm, admixed in most (12/13) cases with variable proportions of lymphocytes, plasma cells, eosinophils, and neutrophils. Additional features included intracytoplasmic hyaline inclusions and a prominent collagenous, sometimes hyalinized stroma. Mitotic activity was relatively low (median, 1 mitosis/10 HPF), but tumor necrosis was frequent (11/13). Local invasion of adjacent structures and lymphovascular invasion were noted in some tumors (4/9 cases with available data for each feature). All were α-inhibin-positive and lacked nuclear reactivity for β-catenin. In addition, all tested cases were positive for epithelial membrane antigen (9/9) and steroidogenic factor-1 (8/8), and 8/10 expressed CD30. Two "index" cases were initially analyzed using a DNA sequencing panel, which identified EWSR1::ATF1 fusions in both. Subsequently, EWSR1::ATF1 fusions were demonstrated in 8 of the remaining 11 cases using fluorescence in situ hybridization or DNA sequencing. One of the 3 cases that were negative for EWSR1::ATF1 harbored ATF1 amplification. This study, therefore, shows that a group of malignant TSCTs resembling seminoma is characterized by α-inhibin and steroidogenic factor-1 positivity, no expression of nuclear β-catenin, frequent CD30 positivity and recurrent EWSR1::ATF1 fusions. We have descriptively termed these neoplasms "inflammatory and nested TSCT." Importantly, inflammatory and nested TSCTs show significant differences in morphology, immunoprofile, molecular biology, and, likely, clinical behavior from Sertoli cell tumors, not otherwise specified and should be classified separately.

Large cell calcifying Sertoli cell tumour: molecular and immunohistochemical assessment of a series comprising non-metastasising and metastasising neoplasms

Large cell calcifying Sertoli cell tumour (LCCSCT) is a type of testicular sex cord-stromal tumour that may occur sporadically or in the context of Carney complex and other genetic syndromes. A subset is clinically malignant, and the molecular mechanisms that drive such aggressive behaviour remain unknown. METHODS AND RESULTS: We analysed 21 samples from 20 patients with LCCSCT (12 non-metastasising and eight metastasising) using PRKAR1A immunohistochemistry (IHC) and next-generation sequencing. All tumours except two (cases 17 and 20, both metastasising) demonstrated loss of PRKAR1A expression. Among 11 cases with interpretable sequencing results, all harboured pathogenic single nucleotide variants of PRKAR1A. Evidence of loss of heterozygosity (LOH) of PRKAR1A was present in all tumours with interpretable zygosity data, but the mechanisms of LOH were different for non-metastasising and metastasising tumours. Non-metastasising tumours demonstrated only copy-neutral LOH, while metastasising tumours demonstrated a spectrum of mechanisms of LOH, including copy-loss LOH, two concurrent mutations or copy-neutral LOH. Relevant molecular findings in non-metastasising LCCSCT were limited to PRKAR1A variants. In contrast, all metastasising LCCSCTs with interpretable data harboured additional pathogenic variants, including (but not restricted to) BRCA2 mutations with evidence of LOH and bi-allelic CDKN2A/B deletions. Three patients harboured PRKAR1A variants of inferred germline origin, including one with Carney complex and two without known syndromic features. CONCLUSIONS: This study further confirms that PRKAR1A IHC is a useful diagnostic tool for both non-metastasising and metastasising tumours and suggests that molecular analyses can be helpful to identify non-metastasising tumours with malignant potential in selected patients. Importantly, these results highlight that germline assessment could be beneficial for all patients presenting with LCCSCT.

Molecular Correlates of Aggressive Behavior and Biologic Progression in Testicular Sertoli Cell Tumor

Sertoli cell tumor (SCT) is the second most common type of sex cord-stromal tumor in men and ∼10% exhibit malignant behavior. Although CTNNB1 variants have been described in SCTs, only a limited number of metastatic cases have been analyzed, and the molecular alterations associated with aggressive behavior remain largely unexplored. This study evaluated a series of nonmetastasizing and metastasizing SCTs using next-generation DNA sequencing to further characterize their genomic landscape. Twenty-two tumors from 21 patients were analyzed. Cases were divided into metastasizing SCTs and nonmetastasizing SCTs. Nonmetastasizing tumors were considered to have aggressive histopathologic features if they exhibited ≥1 of the following: size > 2.4 cm, necrosis, lymphovascular invasion, ≥ 3 mitoses per 10 high-power fields (HPF), severe nuclear atypia or invasive growth. Six patients had metastasizing SCTs and the remaining 15 had nonmetastasizing SCTs; 5 nonmetastasizing tumors had ≥1 aggressive histopathologic feature(s). Gain-of-function CTNNB1 or inactivating APC variants were highly recurrent in nonmetastasizing SCTs (combined frequency >90%), with arm-/chromosomal-level CNVs, loss of 1p and CTNNB1 LOH occurring exclusively in CTNNB1-mutant tumors with aggressive histopathologic features or size >1.5 cm. Nonmetastasizing SCTs were almost invariably driven by WNT pathway activation. In contrast, only 50% of metastasizing SCTs harbored gain-of-function CTNNB1 variants. The remaining 50% of metastasizing SCTs were CTNNB1-wild-type and harbored alterations in TP53, MDM2, CDKN2A/CDKN2B, and TERT pathways. These findings suggest that aggressive SCTs can arise from progression of CTNNB1-mutant benign SCTs, or from CTNNB1-wild type tumors with alterations of TP53, cell cycle regulation, and telomere maintenance pathways.

Acquiring tissue for advanced lung cancer diagnosis and comprehensive biomarker testing: A National Lung Cancer Roundtable best-practice guide

Advances in biomarker-driven therapies for patients with nonsmall cell lung cancer (NSCLC) both provide opportunities to improve the treatment (and thus outcomes) for patients and pose new challenges for equitable care delivery. Over the last decade, the continuing development of new biomarker-driven therapies and evolving indications for their use have intensified the importance of interdisciplinary communication and coordination for patients with or suspected to have lung cancer. Multidisciplinary teams are challenged with completing comprehensive and timely biomarker testing and navigating the constantly evolving evidence base for a complex and time-sensitive disease. This guide provides context for the current state of comprehensive biomarker testing for NSCLC, reviews how biomarker testing integrates within the diagnostic continuum for patients, and illustrates best practices and common pitfalls that influence the success and timeliness of biomarker testing using a series of case scenarios.

Integrating Molecular Sequencing Into the Pathological Diagnosis of Clinically Suspected Non-Small Cell Lung Carcinomas

Cancer panel sequencing has been rapidly adopted into clinical practice for the detection of actionable genetic variants in advanced non-small cell lung carcinomas. Unexpected molecular results may lead to reexamination of the clinical diagnosis; however, this scenario has not been systematically evaluated. We reviewed cancer panel next-generation sequencing results from 1007 consecutive patients performed for the clinical indication of non-small cell lung carcinoma along with the corresponding clinical history and anatomical pathology findings. The final integrative diagnosis was a cancer of extrapulmonary origin in 12 of 1007 patients (1.2%). Molecular evidence supporting the final diagnoses included the detection of an UV radiation-associated mutational signature (n = 6), gene fusions (n = 2), and mutations (n = 4). The integrative diagnoses included undifferentiated melanoma, cutaneous squamous cell, and basal cell carcinomas, thyroid carcinoma, urothelial carcinoma, hepatocellular carcinoma, pancreatic adenocarcinoma, intrahepatic cholangiocarcinoma, and synovial sarcoma. A small but nonnegligible proportion of clinically suspected non-small cell lung carcinomas had a final diagnosis of cancer of extrapulmonary origin after clinical next-generation sequencing. The integration of clinical, microscopic, and molecular evidence can aid diagnosis and guide personalized oncology care.

Updates in pathology and molecular diagnostics to inform the evolving landscape of thoracic surgery and oncology

The pathologic assessment of lung cancers provides essential guidance to the surgeon and oncologist who are considering the best treatment strategies for patients with both early and advanced-stage disease. The management of patients with lung cancer is predicated first and foremost on access to an accurate diagnosis, even when the sample size is limited, as is often the case with use of modern, minimally invasive sampling techniques. Once the diagnosis and disease stage are established, predictive biomarker testing may be essential, particularly for those patients with nonsmall cell lung carcinoma (NSCLC) being considered for immunotherapy or genomic biomarker-driven targeted therapy. This review will discuss the best practices for the diagnosis of NSCLC using morphology and immunohistochemistry, thus providing the surgeon with needed information to understand and critically evaluate pathology reports. Controversial and evolving topics including tumor spread through airspaces, evaluation of multiple tumors, and staging based on invasive tumor size will be addressed. Clinical genomic profiling in NSCLC is driven by published guidelines and reflects evidence based on clinical trials and regulatory approvals. In this fast-moving space, surgeons should be aware of the critical immunohistochemical and genomic biomarkers that drive systemic therapy decisions and anticipate when such testing will be required, both to ensure adequate sampling and to advise the pathologist when tumor material will be required for biomarker analysis. The basic approaches to and sample requirements for molecular biomarker testing will be addressed. As biomarker testing moves exclusively from advanced-stage patients into earlier stage disease, the surgeon should be aware of the relevant markers and work with the pathologist and oncologist to ensure that this information is available to facilitate timely access to therapies not just in the advanced setting, but in consideration of neoadjuvant and adjuvant care.

Myoid gonadal stromal tumours are characterised by recurrent chromosome-level copy number gains: molecular assessment of a multi-institutional series

Myoid gonadal stromal tumours (MGST) represent a rare type of testicular sex cord-stromal tumour that has recently been recognised as a distinct entity by the World Health Organization (WHO) classification of genitourinary tumours. MGSTs affect adult men and have been reported to behave in an indolent fashion. Histologically, MGSTs are pure spindle cell neoplasms that coexpress SMA and S100 protein. Given that the molecular features of these neoplasms remain largely undescribed, we evaluated a multi-institutional series of MGSTs using DNA and RNA sequencing. This study included 12 tumours from 12 patients aged 28 to 57 years. Tumour sizes ranged from 0.6 to 4.3 cm. Aggressive histologic features, such as vascular invasion, necrosis, invasive growth, and atypical mitoses were invariably absent. Mitotic activity was low, with a median of less than 1 mitosis per 10 high power fields (HPF; maximum: 3 mitoses per 10 HPF). Molecular analyses did not identify recurrent mutations or gene fusions. All cases with interpretable copy number variant data (9/10 cases sequenced successfully) demonstrated a consistent pattern of chromosome arm-level and whole-chromosome-level copy number gains indicative of ploidy shifts, with recurrent gains involving chromosomes 3, 6, 7, 8, 9, 11, 12, 14q, 15q, 17, 18q, 20, and 21q. Similar findings have also been recognised in pure spindle cell and spindle-cell predominant sex cord-stromal tumours without S100 protein expression. MGSTs are characterised by ploidy shifts and may be part of a larger spectrum of spindle cell-predominant sex cord-stromal tumours, including cases without S100 protein expression.

Utilizing Electronic Health Records (EHR) and Tumor Panel Sequencing to Demystify Prognosis of Cancer of Unknown Primary (CUP) patients

Cancer of unknown primary (CUP) is a type of cancer that cannot be traced back to its original site and accounts for 3-5% of all cancers. It does not have established targeted therapies, leading to poor outcomes. We developed OncoNPC, a machine learning classifier trained on targeted next-generation sequencing data from 34,567 tumors from three institutions. OncoNPC achieved a weighted F1 score of 0.94 for high confidence predictions on known cancer types (65% of held-out samples). When applied to 971 CUP tumors from patients treated at the Dana-Farber Cancer Institute, OncoNPC identified actionable molecular alterations in 23% of the tumors. Furthermore, OncoNPC identified CUP subtypes with significantly higher polygenic germline risk for the predicted cancer type and significantly different survival outcomes, supporting its validity. Importantly, CUP patients who received first palliative intent treatments concordant with their OncoNPC-predicted cancer sites had significantly better outcomes (H.R. 0.348, 95% C.I. 0.210 - 0.570, p-value 2.32 × 10-5). OncoNPC thus provides evidence of distinct CUP subtypes and offers the potential for clinical decision support for managing patients with CUP.

Association of Machine Learning-Based Assessment of Tumor-Infiltrating Lymphocytes on Standard Histologic Images With Outcomes of Immunotherapy in Patients With NSCLC

Importance

Currently, predictive biomarkers for response to immune checkpoint inhibitor (ICI) therapy in lung cancer are limited. Identifying such biomarkers would be useful to refine patient selection and guide precision therapy.

Objective

To develop a machine-learning (ML)-based tumor-infiltrating lymphocytes (TILs) scoring approach, and to evaluate TIL association with clinical outcomes in patients with advanced non-small cell lung cancer (NSCLC).

Design, Setting, and Participants

This multicenter retrospective discovery-validation cohort study included 685 ICI-treated patients with NSCLC with median follow-up of 38.1 and 43.3 months for the discovery (n = 446) and validation (n = 239) cohorts, respectively. Patients were treated between February 2014 and September 2021. We developed an ML automated method to count tumor, stroma, and TIL cells in whole-slide hematoxylin-eosin-stained images of NSCLC tumors. Tumor mutational burden (TMB) and programmed death ligand-1 (PD-L1) expression were assessed separately, and clinical response to ICI therapy was determined by medical record review. Data analysis was performed from June 2021 to April 2022.

Exposures

All patients received anti-PD-(L)1 monotherapy.

Main Outcomes and Measures

Objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) were determined by blinded medical record review. The area under curve (AUC) of TIL levels, TMB, and PD-L1 in predicting ICI response were calculated using ORR.

Results

Overall, there were 248 (56%) women in the discovery cohort and 97 (41%) in the validation cohort. In a multivariable analysis, high TIL level (≥250 cells/mm2) was independently associated with ICI response in both the discovery (PFS: HR, 0.71; P = .006; OS: HR, 0.74; P = .03) and validation (PFS: HR = 0.80; P = .01; OS: HR = 0.75; P = .001) cohorts. Survival benefit was seen in both first- and subsequent-line ICI treatments in patients with NSCLC. In the discovery cohort, the combined models of TILs/PD-L1 or TMB/PD-L1 had additional specificity in differentiating ICI responders compared with PD-L1 alone. In the PD-L1 negative (<1%) subgroup, TIL levels had superior classification accuracy for ICI response (AUC = 0.77) compared with TMB (AUC = 0.65).

Conclusions and Relevance

In these cohorts, TIL levels were robustly and independently associated with response to ICI treatment. Patient TIL assessment is relatively easily incorporated into the workflow of pathology laboratories at minimal additional cost, and may enhance precision therapy.

Molecular assessment of paratesticular rhabdomyomas demonstrates recurrent findings, including a novel H3C2 p.K37I mutation

Rhabdomyomas are benign tumors with skeletal muscle differentiation that are broadly divided into cardiac and extracardiac types. The latter demonstrate a predilection for head and neck and genital locations and are further subclassified into adult-type rhabdomyoma (ATRM), fetal-type rhabdomyoma (FTRM) and genital rhabdomyoma (GRM). Most extracardiac rhabdomyomas that arise in paratesticular tissues have a somewhat distinctive morphology and have been termed sclerosing rhabdomyomas (SRM). Therefore, we hypothesized that these tumors may harbor recurrent genetic alterations. In this study, we assessed 15 paratesticular rhabdomyomas (11 initially classified as SRM, 2 cellular FTRM and 2 ATRM) using massively parallel DNA and RNA sequencing. Five of 14 successfully sequenced cases harbored a novel H3C2 p.K37I mutation (4 SRM and 1 ATRM). This mutation replaced a highly conserved lysine residue that is a target for epigenetic modifications and plays a role in regulation of DNA replication. Moreover, 4 tumors (2 cellular FTRM, 1 case initially diagnosed as SRM and 1 ATRM) had complex copy number profiles characterized by numerous chromosome-level and arm-level copy number gains, consistent with a ploidy shift. Rereview of the SRM with copy number gains demonstrated that it was significantly more cellular and had a more prominent fascicular architecture than the rest of the SRMs included in this series. Therefore, it was retrospectively reclassified as a cellular FTRM. In conclusion, this study demonstrated that paratesticular rhabdomyomas harbor recurrent somatic H3C2 p.K37I mutations and ploidy shifts.

Molecular Characterization and Therapeutic Approaches to Small Cell Lung Cancer: Imaging Implications

Small cell lung cancer (SCLC) is a highly aggressive malignancy with exceptionally poor prognosis, comprising approximately 15% of lung cancers. Emerging knowledge of the molecular and genomic landscape of SCLC and recent successful clinical applications of new systemic agents have allowed for precision oncology treatment approaches. Imaging is essential for the diagnosis, staging, and treatment monitoring of patients with SCLC. The role of imaging is increasing with the approval of new treatment agents, including immune checkpoint inhibitors, which lead to novel imaging manifestations of response and toxicities. The purpose of this state-of-the-art review is to provide the reader with the latest information about SCLC, focusing on the subtyping of this malignancy (molecular characterization) and the emerging systemic therapeutic approaches and their implications for imaging. The review will also discuss the future directions of SCLC imaging, radiomics and machine learning.

To Rb or Not to Rb: Uncovering Unique Subsets of Small Cell Lung Carcinoma

The use of IHC as a surrogate for specific underlying genomic alterations has allowed for increasingly comprehensive and accurate diagnosis of small cell lung carcinoma (SCLC). This is especially relevant in light of the increasing recognition of the biologic heterogeneity of this aggressive and difficult-to-treat lung tumor. Integrated genomic and IHC profiling of Rb status in SCLC yields new diagnostic insights and has translational implications. See related article by Febres-Aldana et al., p. 4702.

Clinical and molecular validation of BAP1, MTAP, P53, and Merlin immunohistochemistry in diagnosis of pleural mesothelioma

BAP1 and MTAP immunostains play an important role in diagnosis of mesothelioma, but additional markers are needed to increase sensitivity. We analyzed 84 pleural mesotheliomas (51 epithelioid, 27 biphasic, 6 sarcomatoid) by a hybrid-capture next-generation sequencing (NGS) panel including complete coverage of coding and splicing regions for BAP1, CDKN2A/MTAP, NF2, and TP53 and correlated molecular findings with diagnostic immunostains for BAP1, MTAP, Merlin, and p53, respectively. Fifty-seven reactive mesothelial proliferations served as benign comparators. Loss of BAP1, MTAP, and Merlin protein expression were, respectively, 54%, 46%, and 52% sensitive and 100% specific for mesothelioma. Two-marker immunopanels of BAP1 + MTAP, BAP1 + Merlin, and MTAP + Merlin were 79%, 85%, and 71% sensitive for mesothelioma, while a three-marker immunopanel of BAP1 + MTAP + Merlin was 90% sensitive. Diffuse (mutant-pattern) p53 immunostaining was seen in only 6 (7%) tumors but represented the only immunohistochemical abnormality in 2 cases. Null-pattern p53 was not specific for malignancy. An immunopanel of BAP1 + MTAP + Merlin + p53 was 93% sensitive for mesothelioma, and panel NGS detected a pathogenic alteration in BAP1, MTAP, NF2, and/or TP53 in 95%. Together, 83 (99%) of 84 tumors showed a diagnostic alteration by either immunohistochemistry or panel NGS. Adding Merlin to the standard BAP1 + MTAP immunopanel increases sensitivity for mesothelioma without sacrificing specificity. p53 immunohistochemistry and panel NGS with complete coverage of BAP1, CDKN2A/MTAP, TP53, and NF2 may be useful in diagnostically challenging cases.

NTRK -Rearranged Uterine Sarcomas: Clinicopathologic Features of 15 Cases, Literature Review, and Risk Stratification

NTRK -rearranged uterine sarcomas are rare spindle cell neoplasms that typically arise in the uterine cervix of young women. Some tumors recur or metastasize, but features which predict behavior have not been identified to date. Distinguishing these tumors from morphologic mimics is significant because patients with advanced stage disease may be treated with TRK inhibitors. Herein, we present 15 cases of NTRK- rearranged uterine sarcomas, the largest series to date. Median patient age was 35 years (range: 16 to 61). The majority arose in the uterine cervix (n=14) and all but 2 were organ-confined at diagnosis. Tumors were composed of an infiltrative, fascicular proliferation of spindle cells and most showed mild-to-moderate cytologic atypia. All were pan-TRK positive by immunohistochemistry (13/13); S100 (11/13) and CD34 (6/10) were usually positive. RNA or DNA sequencing found NTRK1 (10/13) and NTRK3 (3/13) fusions with partners TPR , TPM3 , EML4 , TFG , SPECC1L , C16orf72 , and IRF2BP2 . Unusual morphology was seen in 2 tumors which were originally diagnosed as unclassifiable uterine sarcomas, 1 of which also harbored TP53 mutations. Follow up was available for 9 patients, of whom 3 died of disease. By incorporating outcome data of previously reported tumors, adverse prognostic features were identified, including a mitotic index ≥8 per 10 high-power fields, lymphovascular invasion, necrosis, and NTRK3 fusion. Patients with tumors which lacked any of these 4 features had an excellent prognosis. This study expands the morphologic spectrum of NTRK -rearranged uterine sarcomas and identifies features which can be used for risk stratification.

Dissecting the clinicopathologic, genomic, and immunophenotypic correlates of KRASG12D-mutated non-small-cell lung cancer

BACKGROUND

Allele-specific KRAS inhibitors are an emerging class of cancer therapies. KRAS-mutant (KRASMUT) non-small-cell lung cancers (NSCLCs) exhibit heterogeneous outcomes, driven by differences in underlying biology shaped by co-mutations. In contrast to KRASG12C NSCLC, KRASG12D NSCLC is associated with low/never-smoking status and is largely uncharacterized.

PATIENTS AND METHODS

Clinicopathologic and genomic information were collected from patients with NSCLCs harboring a KRAS mutation at the Dana-Farber Cancer Institute (DFCI), Memorial Sloan Kettering Cancer Center, MD Anderson Cancer Center, and Imperial College of London. Multiplexed immunofluorescence for CK7, programmed cell death protein 1 (PD-1), programmed death-ligand 1 (PD-L1), Foxp3, and CD8 was carried out on a subset of samples with available tissue at the DFCI. Clinical outcomes to PD-(L)1 inhibition ± chemotherapy were analyzed according to KRAS mutation subtype.

RESULTS

Of 2327 patients with KRAS-mutated (KRASMUT) NSCLC, 15% (n = 354) harbored KRASG12D. Compared to KRASnon-G12D NSCLC, KRASG12D NSCLC had a lower pack-year (py) smoking history (median 22.5 py versus 30.0 py, P < 0.0001) and was enriched in never smokers (22% versus 5%, P < 0.0001). KRASG12D had lower PD-L1 tumor proportion score (TPS) (median 1% versus 5%, P < 0.01) and lower tumor mutation burden (TMB) compared to KRASnon-G12D (median 8.4 versus 9.9 mt/Mb, P < 0.0001). Of the samples which underwent multiplexed immunofluorescence, KRASG12D had lower intratumoral and total CD8+PD1+ T cells (P < 0.05). Among 850 patients with advanced KRASMUT NSCLC who received PD-(L)1-based therapies, KRASG12D was associated with a worse objective response rate (ORR) (15.8% versus 28.4%, P = 0.03), progression-free survival (PFS) [hazard ratio (HR) 1.51, 95% confidence interval (CI) 1.45-2.00, P = 0.003], and overall survival (OS; HR 1.45, 1.05-1.99, P = 0.02) to PD-(L)1 inhibition alone but not to chemo-immunotherapy combinations [ORR 30.6% versus 35.7%, P = 0.51; PFS HR 1.28 (95%CI 0.92-1.77), P = 0.13; OS HR 1.36 (95%CI 0.95-1.96), P = 0.09] compared to KRASnon-G12D.

CONCLUSIONS

KRASG12D lung cancers harbor distinct clinical, genomic, and immunologic features compared to other KRAS-mutated lung cancers and worse outcomes to PD-(L)1 blockade. Drug development for KRASG12D lung cancers will have to take these differences into account.

Biomarker testing in cancer management- can one size fit all?

Biomarker-guided treatment selection has transformed cancer management. Pruis et al. provide a powerful example of the challenges and promises of whole genome sequencing to match patients with advanced cancer for precision oncology studies and targeted therapies. Expanding genomic testing platforms are reviewed with a view towards future applications to inform clinical cancer research and practice.

Predictive Biomarkers for Immunotherapy in Lung Cancer: Perspective from the IASLC Pathology Committee

Immunotherapy including immune checkpoint inhibitors (ICIs) has become the backbone of treatment for the majority of lung cancers with advanced or metastatic disease. In addition, they have increasingly been used for early-stage tumors in neoadjuvant and adjuvant settings. Unfortunately, however, only a subset of patients experiences meaningful response to ICIs. While PD-L1 protein expression by immunohistochemistry (IHC) has played a role as the principle predictive biomarker for immunotherapy, its performance may not be optimal, and it suffers multiple practical issues with different companion diagnostic assays approved. Similarly, tumor mutation burden (TMB) has multiple technical issues as a predictive biomarker for ICIs. Now, ongoing research on tumor and host immune-specific factors has identified immunotherapy biomarkers that may provide better response and prognosis prediction, in particular in a multimodal approach. This review by the IASLC Pathology Committee provides an overview of various immunotherapy biomarkers including updated data on PD-L1 IHC and TMB, and assesssments of neoantigens, genetic and epigenetic signatures, immune microenvironment by IHC and transcriptomics, as well as microbiome and pathological response to neoadjuvant immunotherapies. The aim of this review is to underline the efficacy of new individual or combined predictive biomarkers beyond PD-L1 IHC and TMB.

Genomic and biological study of fusion genes as resistance mechanisms to EGFR inhibitors

The clinical significance of gene fusions detected by DNA-based next generation sequencing remains unclear as resistance mechanisms to EGFR tyrosine kinase inhibitors in EGFR mutant non-small cell lung cancer. By studying EGFR inhibitor-resistant patients treated with a combination of an EGFR inhibitor and a drug targeting the putative resistance-causing fusion oncogene, we identify patients who benefit and those who do not from this treatment approach. Through evaluation including RNA-seq of potential drug resistance-imparting fusion oncogenes in 504 patients with EGFR mutant lung cancer, we identify only a minority of them as functional, potentially capable of imparting EGFR inhibitor resistance. We further functionally validate fusion oncogenes in vitro using CRISPR-based editing of EGFR mutant cell lines and use these models to identify known and unknown drug resistance mechanisms to combination therapies. Collectively, our results partially reveal the complex nature of fusion oncogenes as potential drug resistance mechanisms and highlight approaches that can be undertaken to determine their functional significance.

An integrated somatic and germline approach to aid interpretation of germline variants of uncertain significance in cancer susceptibility genes

Genomic profiles of tumors are often unique and represent characteristic mutational signatures defined by DNA damage or DNA repair response processes. The tumor-derived somatic information has been widely used in therapeutic applications, but it is grossly underutilized in the assessment of germline genetic variants. Here, we present a comprehensive approach for evaluating the pathogenicity of germline variants in cancer using an integrated interpretation of somatic and germline genomic data. We have previously demonstrated the utility of this integrated approach in the reassessment of pathogenic germline variants in selected cancer patients with unexpected or non-syndromic phenotypes. The application of this approach is presented in the assessment of rare variants of uncertain significance (VUS) in Lynch-related colon cancer, hereditary paraganglioma-pheochromocytoma syndrome, and Li-Fraumeni syndrome. Using this integrated method, germline VUS in PMS2, MSH6, SDHC, SHDA, and TP53 were assessed in 16 cancer patients after genetic evaluation. Comprehensive clinical criteria, somatic signature profiles, and tumor immunohistochemistry were used to re-classify VUS by upgrading or downgrading the variants to likely or unlikely actionable categories, respectively. Going forward, collation of such germline variants and creation of cross-institutional knowledgebase datasets that include integrated somatic and germline data will be crucial for the assessment of these variants in a larger cancer cohort.