Gupta, Sounak

Histopathology has remained a cornerstone for biomedical tissue assessment for over a century, with a resource-intensive workflow involving biopsy or excision, gross examination, sampling, tissue processing to snap frozen or formalin-fixed paraffin-embedded blocks, sectioning, staining, optical imaging, and microscopic assessment. Emerging chemical imaging approaches, including stimulated Raman scattering (SRS) microscopy, can directly measure inherent molecular composition in tissue (thereby dispensing with the need for tissue processing, sectioning, and using dyes) and can use artificial intelligence (AI) algorithms to provide high-quality images. Here we show the integration of SRS microscopy in a pathology workflow to rapidly record chemical information from minimally processed fresh-frozen prostate tissue. Instead of using thin sections, we record data from intact thick tissues and use optical sectioning to generate images from multiple planes. We use a deep learning–based processing pipeline to generate virtual hematoxylin and eosin images. Next, we extend the computational method to generate archival-quality images in minutes, which are equivalent to those obtained from hours/days-long formalin-fixed, paraffin-embedded processing. We assessed the quality of images from the perspective of enabling pathologists to make decisions, demonstrating that the virtual stained image quality was diagnostically useful and the interpathologist agreement on prostate cancer grade was not impacted. Finally, because this method does not wash away lipids and small molecules, we assessed the utility of lipid chemical composition in determining grade. Together, the combination of chemical imaging and AI provides novel capabilities for rapid assessments in pathology by reducing the complexity and burden of current workflows. Significance: Archival-quality (formalin-fixed paraffin-embedded), thin-section diagnostic images are obtained from thick-cut, fresh-frozen prostate tissues without dyes or stains to expedite cancer histopathology by combining SRS microscopy and machine learning.

Abstract Background Tumor cell phenotypes and anti-tumor immune responses are shaped by local metabolite availability, but intratumoral metabolite heterogeneity (IMH) and its phenotypic consequences remain poorly understood. In vitro mechanistic studies have demonstrated that the anti-tumor activity of lymphoid and myeloid cell populations is mediated by metabolite availability and signaling in the TME, raising the possibility that the immune response and metabolism of ccRCC tumors coevolve and jointly influence the likelihood that a patient responds to therapy.. However, both the broad patterns of coordination between metabolite abundance and TME cellular composition, as well as the precise cell populations producing metabolic phenotypes of interest, remain unknown. Methods To study IMH, we multiregionally profiled the metabolome, transcriptome, and genome of 187 tumor/normal regions from 31 clear cell renal cell carcinoma (ccRCC) patients. Using these measurements and additional multimodal metabolomic/transcriptomic profiling of ccRCC and other diseases, we developed computational models that can be used to understand RNA-metabolite covariation and ultimately impute metabolite levels from RNA sequencing data. Results Analysis of intratumoral metabolite-RNA covariation revealed that the immune composition of the microenvironment, and especially the abundance of myeloid cells, drove intratumoral metabolite variation. Motivated by the strength of RNA-metabolite covariation and the clinical significance of RNA biomarkers in ccRCC, we deployed and benchmarked a machine learning method (MIRTH) to impute metabolite levels directly from RNA sequencing data of primary and metastatic ccRCC tumors. We inferred metabolomic profiles from RNA sequencing data of ccRCC patients enrolled in 6 clinical trials, ultimately identifying specific metabolite biomarkers associated with response to anti-angiogenic agents. Conclusions Local metabolic phenotypes therefore emerge in tandem with the immune microenvironment and associate with therapeutic sensitivity. CDMRP DOD Funding: yes

Abstract Objectives There is a paucity of data on penile amyloidosis. We aimed to assess the frequency of different amyloid types in surgical specimens from the penis involved by amyloidosis and correlate relevant clinicopathologic parameters with proteomic findings. Methods Since 2008, our reference laboratory has performed liquid chromatography/tandem mass spectrometry (LC-MS/MS) for amyloid typing. The institutional pathology archive and reference laboratory database were queried to retrospectively identify all penile surgical pathology specimens with LC-MS/MS results between January 1, 2008, and November 23, 2022. Archived H&E-stained and Congo red–stained sections were re-reviewed. Results Twelve cases of penile amyloidosis were identified, which represented 0.35% (n = 3,456) of penile surgical specimens. AL-type amyloid was most frequent (n = 7), followed by keratin-type amyloid (n = 3) and ATTR (transthyretin)–type amyloid (n = 2). AL-type amyloid cases often showed diffuse dermal/lamina propria deposition, whereas all keratin-type amyloid cases were localized to the superficial dermis. Two cases with keratin-type amyloid had concomitant cutaneous findings (penile intraepithelial neoplasia and condyloma). Conclusions This series, the largest to date, demonstrates that penile amyloidosis has a heterogeneous proteomic landscape. To the best of our knowledge, this is the first study describing ATTR (transthyretin)–type penile amyloid.

548 Background: PD-L1 and B7-H3 have been found to be overexpressed in urothelial carcinoma (UC) of the urinary bladder. Recent studies have also demonstrated that B7-H3 and PD-L1 can promote resistance to platinum-based drugs but the predictive value of B7-H3 expression in patients treated with platinum-based chemotherapy is unknown. This study aims to investigate the association of PD-L1 and B7-H3 tumor expression with oncological outcomes in patients who underwent radical cystectomy (RC) and received subsequent adjuvant chemotherapy. Methods: Immunohistochemistry was performed on paraffin-embedded sections from bladder and lymph node specimens of 81 patients who had RC for bladder cancer. PD-L1 and B7-H3 expression on tumor cells was assessed by immunohistochemistry in both primary tumors and lymph node specimens. Association with clinicopathologic outcomes was determined using Fisher’s exact test and postoperative survival using Kaplan–Meier survival curves and Cox regression model. Results: B7-H3 expression in cystectomy specimens was more common than PD-L1 expression (72.8% vs. 35.8%). For both markers, no association was found with pathologic tumor stage, lymph node (LN) status, and histological subtype. Similar findings were observed for double-positive tumors (PD-L1+B7-H3+). Concordance between the primary tumor and patient-matched lymph nodes was found in 76.2% and 54.1% of patients for PD-L1 and B7-H3, respectively. PD-L1 tumor expression was not associated with oncologic outcomes. However, B7-H3 expression was associated with recurrence-free survival (HR: 2.38, 95% CI 1.06–5.31, p = 0.035) and cancer-specific survival (HR: 2.67, 95% CI 1.18–6.04, p = 0.019). Conclusions: In our single institutional study, B7-H3 is highly expressed in patients with UC treated with adjuvant chemotherapy and it was associated with decreased recurrence-free survival and cancer-specific survival. Pending further validation in larger cohorts, B7-H3 expression may function as a predictor of response to adjuvant chemotherapy and thus be useful in patient and regimen selection.

Context.— Epithelioid angiomyolipomas (eAMLs) are rare tumors of the kidney that occur in patients with tuberous sclerosis complex or in a sporadic setting; a subset of these tumors exhibit metastatic behavior. Objective.— To analyze molecular profiling data to identify pathogenic alterations in rare cases of metastatic eAML, and to identify immunohistochemistry (IHC)-based surrogate markers. Design.— Molecular profiling data from the American Association for Cancer Research GENIE registry was accessed for 23 patients with angiomyolipomas, and 9 of 16 patients with eAMLs in our institutional registry were evaluated with next-generation sequencing. IHC was performed to screen for alterations of P53, RB, and ATRX for all 16 institutional cases. Results.— Combined alterations of 5 tumor-suppressor genes (TP53, ATRX, RB1, APC, and NF1) were identified using next-generation sequencing in 7 of 8 (88%) patients with metastatic disease compared to a single patient with nonmetastatic disease (RB1 variant of uncertain significance; 1 of 24, 4%). No cases with abnormal IHC results were identified in 11 patients with nonmetastatic disease compared to 3 of 5 patients with metastatic disease. Conclusions.— Our results show that the majority of metastatic eAMLs have mutations of 5 tumor-suppressor genes (TP53, ATRX, RB1, APC, and NF1), while these are rare in patients with nonmetastatic disease. Furthermore, IHC for P53, RB, and ATRX may serve as a screen for a subset of these alterations in resource-limited settings. These findings, if validated in larger data sets, have the potential to predict metastatic behavior in eAMLs.

Introduction. Chromophobe renal cell carcinoma (chromophobe RCC) is the third major subcategory of renal tumors after clear cell RCC and papillary RCC, accounting for approximately 5% of all RCC subtypes. Other oncocytic neoplasms seen commonly in surgical pathology practice include the eosinophilic variant of chromophobe RCC, renal oncocytoma, and low-grade oncocytic unclassified RCC. Methods. In our recent next-generation sequencing based study, we nominated a lineage-specific novel biomarker LINC01187 (long intergenic non-protein coding RNA 1187) which was found to be enriched in chromophobe RCC. Like KIT (cluster of differentiation 117; CD117), a clinically utilized chromophobe RCC related biomarker, LINC01187 is expressed in intercalated cells of the nephron. In this follow-up study, we performed KIT immunohistochemistry and LINC01187 RNA in situ hybridization (RNA-ISH) on a cohort of chromophobe RCC and other renal neoplasms, characterized the expression patterns, and quantified the expression signals of the two biomarkers in both primary and metastatic settings. Results. LINC01187, in comparison to KIT, exhibits stronger and more uniform expression within tumors while maintaining temporal and spatial consistency. LINC01187 also is devoid of intra-tumoral heterogeneous expression pattern, a phenomenon commonly noted with KIT. Conclusions. LINC01187 expression can augment the currently utilized KIT assay and help facilitate easy microscopic analyses in routine surgical pathology practice.

Abstract Purpose: The identification of variants of uncertain significance (VUS) in the BRCA1 and BRCA2 genes by hereditary cancer testing poses great challenges for the clinical management of variant carriers. The ACMG/AMP (American College of Medical Genetics and Genomics/Association for Molecular Pathology) variant classification framework, which incorporates multiple sources of evidence, has the potential to establish the clinical relevance of many VUS. We sought to classify the clinical relevance of 133 single-nucleotide substitution variants encoding missense variants in the DNA-binding domain (DBD) of BRCA2 by incorporating results from a validated functional assay into an ACMG/AMP-variant classification model from a hereditary cancer–testing laboratory. Experimental Design: The 133 selected VUS were evaluated using a validated homology-directed double-strand DNA break repair (HDR) functional assay. Results were combined with clinical and genetic data from variant carriers in a rules-based variant classification model for BRCA2. Results: Of 133 missense variants, 44 were designated as non-functional and 89 were designated as functional in the HDR assay. When combined with genetic and clinical information from a single diagnostic laboratory in an ACMG/AMP-variant classification framework, 66 variants previously classified by the diagnostic laboratory were correctly classified, and 62 of 67 VUS (92.5%) were reclassified as likely pathogenic (n = 22) or likely benign (n = 40). In total, 44 variants were classified as pathogenic/likely pathogenic, 84 as benign/likely benign, and 5 remained as VUS. Conclusions: Incorporation of HDR functional analysis into an ACMG/AMP framework model substantially improves BRCA2 VUS re-classification and provides an important tool for determining the clinical relevance of individual BRCA2 VUS.

BACKGROUND: Immune checkpoint inhibitors are an important therapeutic option for urothelial carcinoma, but durable responses are achieved in a minority of patients. Identifying pre-treatment biomarkers that may predict response to these therapies or who exhibit intrinsic resistance, is of paramount importance. OBJECTIVE: To explore the prevalence of PD-L1 copy number alteration in urothelial carcinoma and correlate with response to immune checkpoint inhibitors. METHODS: We analyzed a cohort of 1050 carcinomas of the bladder and upper urinary tract that underwent targeted next generation sequencing, prospectively. We assessed PD-L1 protein expression, copy number status (next generation sequencing/FISH), and detailed treatment response. RESULTS: We identified 9 tumors with PD-L1 amplification and 9 tumors with PD-L1 deletion. PD-L1 protein expression was the highest in PD-L1 amplified tumors. Of the 9 patients whose tumors harbored PD-L1 amplification, 6 received immunotherapy with 4 deriving clinical benefit, and 2 achieving durable response. Of the 9 patients whose tumors had PD-L1 copy number losses, 4 received immunotherapy with 3 experiencing disease progression. CONCLUSIONS: PD-L1 copy number alterations may serve as potential biomarkers of response to immunotherapy in urothelial carcinoma patients, if validated in larger cohorts.