Elevation of Unsaturated Lipid Species is Accompanied by the Upregulation of Stearoyl-CoA Desaturase in Ovarian Clear Cell Carcinoma

Background Cancer metabolism is associated with enhanced lipogenesis required for rapid growth and proliferation. However, the magnitude of dysregulation of diverse lipid species mostly remain to be characterized, particularly in understudied cancers such as ovarian clear cell carcinoma (OCCC). Further, formalin-fixed paraffin-embedded (FFPE) specimen represent valuable and readily available resources for laboratory investigations but are still underutilized for lipidomics studies. Here we implemented an integrated workflow to investigate lipidomic alterations in OCCC, utilizing FFPE specimen. Methods Lipid extraction of FFPE specimen was carried out by using 1-butanol and methanol in 1:1 (v/v), followed by targeted LC-MS/MS to identify the lipidomic changes in FFPE specimen from OCCC (n=14) as compared to uninvolved contralateral ovarian tissue (n=14). Immunohistochemistry (IHC) assays were implemented to evaluate the expression levels of stearoyl-CoA desaturase (SCD), the rate-limiting enzyme for the synthesis of monounsaturated fatty acids, in OCCC and control tissue specimen. Results We quantified 340 lipid species representing 29 lipid classes. We observed differential regulation of unsaturated lipid species belonging to several glycerophospholipid classes including ether-linked phospholipids, and trihexosylceramide species. We confirmed upregulation of SCD in OCCC by IHC assays. Conclusions By using lipidomic and IHC analysis of archival tissue samples, we were able to provide novel insights into the molecular alterations in OCCC. We show the feasibility of using FFPE specimen to carry out detailed lipidomic analysis of archival cancer samples.

Mutational profiling of micro-dissected pre-malignant lesions from archived specimens

Background Systematic cancer screening has led to the increased detection of pre-malignant lesions (PMLs). The absence of reliable prognostic markers has led mostly to over treatment resulting in potentially unnecessary stress, or insufficient treatment and avoidable progression. Importantly, most mutational profiling studies have relied on PML synchronous to invasive cancer, or performed in patients without outcome information, hence limiting their utility for biomarker discovery. The limitations in comprehensive mutational profiling of PMLs are in large part due to the significant technical and methodological challenges: most PML specimens are small, fixed in formalin and paraffin embedded (FFPE) and lack matching normal DNA. Methods Using test DNA from a highly degraded FFPE specimen, multiple targeted sequencing approaches were evaluated, varying DNA input amount (3–200 ng), library preparation strategy (BE: Blunt-End, SS: Single-Strand, AT: A-Tailing) and target size (whole exome vs. cancer gene panel). Variants in high-input DNA from FFPE and mirrored frozen specimens were used for PML-specific variant calling training and testing, respectively. The resulting approach was applied to profile and compare multiple regions micro-dissected (mean area 5 mm2) from 3 breast ductal carcinoma in situ (DCIS). Results Using low-input FFPE DNA, BE and SS libraries resulted in 4.9 and 3.7 increase over AT libraries in the fraction of whole exome covered at 20x (BE:87%, SS:63%, AT:17%). Compared to high-confidence somatic mutations from frozen specimens, PML-specific variant filtering increased recall (BE:85%, SS:80%, AT:75%) and precision (BE:93%, SS:91%, AT:84%) to levels expected from sampling variation. Copy number alterations were consistent across all tested approaches and only impacted by the design of the capture probe-set. Applied to DNA extracted from 9 micro-dissected regions (8 PML, 1 normal epithelium), the approach achieved comparable performance, illustrated the data adequacy to identify candidate driver events (GATA3 mutations, ERBB2 or FGFR1 gains, TP53 loss) and measure intra-lesion genetic heterogeneity. Conclusion Alternate experimental and analytical strategies increased the accuracy of DNA sequencing from archived micro-dissected PML regions, supporting the deeper molecular characterization of early cancer lesions and achieving a critical milestone in the development of biology-informed prognostic markers and precision chemo-prevention strategies.

Mutational profiling of micro-dissected pre-malignant lesions from archived specimens

BackgroundSystematic cancer screening has led to the increased detection of pre-malignant lesions (PMLs). The absence of reliable prognostic markers has led mostly to over treatment resulting in potentially unnecessary stress, or potentially insufficient treatment and avoidable progression. Importantly, most mutational profiling studies have relied on PML synchronous to invasive cancer, or performed in patients without outcome information, hence limiting their utility for biomarker discovery. The limitations in comprehensive mutational profiling of PMLs are in large part due to the significant technical and methodological challenges: most PML specimens are small, fixed in formalin and paraffin embedded (FFPE) and lack matching normal DNA.MethodsUsing test DNA from a highly degraded FFPE specimen, multiple targeted sequencing approaches were evaluated, varying DNA input amount (3-200 ng), library preparation strategy (BE: Blunt-End, SS: Single-Strand, AT: A-Tailing) and target size (whole exome vs cancer gene panel). Variants in high-input DNA from FFPE and mirrored frozen specimens were used for PML-specific variant calling training and testing, respectively. The resulting approach was applied to profile and compare multiple regions micro-dissected (mean area 5 mm2) from 3 breast ductal carcinoma in situ (DCIS).ResultsUsing low-input FFPE DNA, BE and SS libraries resulted in 4.9 and 3.7 increase over AT libraries in the fraction of whole exome covered at 20x (BE:87%, SS:63%, AT:17%). Compared to high-confidence somatic mutations from frozen specimens, PML-specific variant filtering increased recall (BE:85%, SS:80%, AT:75%) and precision (BE:93%, SS:91%, AT:84%) to levels expected from sampling variation. Copy number alterations were consistent across all tested approaches and only impacted by the design of the capture probe-set. Applied to DNA extracted from 9 micro-dissected regions (8 PML, 1 normal epithelium), the approach achieved comparable performance, illustrated the data adequacy to identify candidate driver events (GATA3 mutations, ERBB2 or FGFR1 gains, TP53 loss) and measure intra-lesion genetic heterogeneity.ConclusionAlternate experimental and analytical strategies increased the accuracy of DNA sequencing from archived micro-dissected PML regions, supporting the deeper molecular characterization of early cancer lesions and achieving a critical milestone in the development of biology-informed prognostic markers and precision chemo-prevention strategies.

Differential stromal reprogramming in benign and malignant naturally occurring canine mammary tumours identifies disease-promoting stromal components

The importance of cancer-associated stroma (CAS) for initiation and progression of cancer is well accepted. However, as stromal changes in benign forms of naturally occurring tumours are poorly understood, it remains unclear how CAS from benign and malignant tumours compare. Spontaneous canine mammary tumours are viewed as excellent models of human mammary carcinomas (mCA). We have recently reported highly conserved stromal reprogramming between canine and human mCA based on transcriptome analysis of laser-capture-microdissected FFPE specimen. To identify stromal changes between benign and malignant mammary tumours, we have analysed CAS and matched normal stroma from 13 canine mammary adenomas and compared them to 15 canine mCA. Our analyses revealed distinct stromal reprogramming even in small benign tumours. While similarities in stromal reprogramming exist, the CAS signature clearly distinguished adenomas from mCA, suggesting that it may reliably discriminate between benign and malignant tumours. We identified strongly discriminatory genes and found strong differential enrichment in several hallmark signalling pathways between benign and malignant CAS. The distinction between CAS from adenoma and mCA was further substantiated by differential abundance in cellular composition. Finally, to determine key players in CAS reprograming between adenomas and mCA, a network-based gene screening method identified modules of co-expressing genes with distinct expression profile in benign and malignant CAS, and revealed several hub genes as potential molecular drivers in CAS. Given the relevance of canine CAS as a model for the human disease, our approach identifies potential stromal drivers of tumour malignancy with implications for human mCA.Summary statementRNAsequencing-based analysis of stromal reprogramming between benign and malignant naturally occurring canine mammary tumours identifies potential molecular drivers in cancer-associated stroma that support tumour growth and malignancy.

Carcinomas of the renal medulla: A comprehensive genomic profiling (CGP) study.

640 Background: Collecting duct carcinoma (CDC) and renal medullary carcinoma (RMC) represent rare tumors that arise in the renal medulla are therapy resistant tumors that progress rapidly. Methods: DNA was extracted from 40 microns of FFPE specimen from refractory CDC (46 cases) and RMC (24 cases). CGPwas performed using a hybrid-capture, adaptor ligation based next generation sequencing assayto a mean coverage depth of > 800X. Tumor mutational burden (TMB) was calculated from a minimum of 1.11 Mb of sequenced DNA as previously described and reported as mutations/Mb. Microsatellite instability status (MSI) was determined on 114 loci. Results: All CDC patients were older and more frequently male (Table). Sickle cell trait was identified in both CDC and RMC, but far more frequently associated with RMC. All (100%) of CDC and RMC were clinically advanced Stage III and IV tumors with the primary tumor used for CGP in 70% of cases and a metastasis biopsy was sequenced in 30%. All (100%) CDC and RMC were intermediate (Grade 3) or high grade (Grade 4). In both tumor types, the GA/tumor was relatively low and there were no (0%) VHL GA. SMARCB1 GA were significantly more frequent in RMC than CDC but common in both tumors. Targeted therapies for kinase ( EGFR, RET) and MTOR ( NF2, TSC2) pathways were more frequent in CDC than RMC. At 1.8 mut/Mb, the median TMB was low for both tumor types with no (0%) of cases showing≥20 mut/Mb. No (0%) of the CDC or RMC cases featured MSI-high status. Conclusions: In addition to their histologic differences, the frequencies and types of GA seen in CDC differ significantly from that seen in RMC. The opportunities for biomarker driven targeted therapies for bothCDCand RMC appear limited with rare opportunities to target GA in TKGFR and MTOR pathways for CDC. Similarly, the relatively low TMB and absence of MSI-High status in CDC and RMCalso predicts that these tumors may be resistant to immunotherapies.[Table: see text]

Stromal infiltrating CD8+ and CD20+ lymphocytes and CD204+ M2 macrophages but not PD-L1 expression on tumor cells are prognosticators for patients with resectable thymic carcinoma.

e20002 Background: Thymic carcinoma (TMCA) is a rare malignant disease, and standard systemic chemotherapy has not been established. Tumor microenvironment (TME) that consists of tumor cells (TCs), tumor-infiltrating immune cells (TIICs) and stromal cells is thought to be an important biological feature of cancer behavior. The aim of this study was to analyze TME of TMCA, focusing the TIICs’ characteristics and the PD-L1 expression in the TC and TIIs and their impact on the clinical outcome. Methods: Fifty-one TMCA specimen with median observation period 33.8 months (range: 0.2-351) were collected. We evaluated the immunohistochemical profile of TIIs using antibodies against CD8, CD20 and FoxP3 for TIICs, CD204 for tumor-associated macrophages (TAMs), and PD-L1(SP142) expression of both TIICs and TCs using representative FFPE specimen. The density (median positive cell number per 1 mm2) of TIICs or TAMs was evaluated in intraepithelial (IE) and tumor stromal (TS) areas separately by using an automated image analyzer. Statistical analysis was performed using SPSS (version 24) and used p < 0.05 as significant level. Results: 51.9% (n = 26) had recurrent disease, and 31% (n = 16) survive without tumor. Of recurrent group, the density of CD8+ (54.5 vs 432) and CD20+ (35.9 vs. 516) TIIs, as well as the CD8+/CD204+, CD20+/CD204+ ratio in TS were significantly lower and FOXP3+ (590 vs 176) in TS was higher than that of non-recurrent group (Mann-Whitney U-test, two-sided). In the IE area, the lower CD20+/CD204+ ratio associated with recurrence. The CD20 and FOXP3 TIIs in TS also associated with the overall survival. There was no significant association between CD204 or PD-L1 expression and patients’ outcome. Conclusions: Our retrospective study showed the density of CD8+, CD20+ and FOXP3+ stromal-infiltrating lymphocytes and CD204+ M2 macrophage were prognostic factors for patients with resectable TMCA. Host immune reaction in TME might be one of the important prognostic factors for TMCA.

Comprehensive genomic profiling of urethral cancer to reveal distinctive features compared to bladder cancer.

429 Background: Relapsed and refractory urethral cancer (UrethC) is a rare form of genito-urinary malignancy that includes urothelial carcinoma (UC), squamous cell carcinoma (SCC), adenocarcinoma (AC) and clear cell carcinoma (CCC) subtypes. No standard treatment exists. Methods: DNA was extracted from 40 microns of FFPE specimen from 46 cases of mUrethC. Comprehensive genomic profiling (CGP) was performed using a hybrid-capture, adaptor ligation based next generation sequencing assay to a mean coverage depth of >500X. Tumor mutational burden (TMB) was calculated from a minimum of 1.11 Mb of sequenced DNA as previously described and reported as mutations/Mb. The results were analyzed for all classes of genomic alterations (GA), including base substitutions, insertions and deletions (short variants; SV), fusions, and copy number changes including amplifications (amp) and homozygous deletions. Results: The clinical features, GA, TMB findings in the mUrethC patients and the subtypes of UrethC are shown in the Table. In comparison with 1,183 similarly profiled UC of the bladder (UCB), all 46 mUrethC and the 21 urothelial mUrethC as a separate group widely differed in GA frequencies. With the exception of similar TP53 GA frequencies, there were significantly lower GA in ERBB2, FGFR1-3 and PIK3CAin the mUrethC cases (p<0.0001 for all comparisons) In addition, mUrethC featured as significantly lower frequency of TMB > 20 mut/Mb (4%; p=0.0001). Conclusions: CGP of mUrethC reveals distinctive genomic alteration frequencies among the 4 disease subtypes with higher numbers of GA in the AC than in the UC, SCC and CCC. The TMB appears to be lower in mUrethC than classically seen in UCB where checkpoint inhibition is now approved. Further study of this rare form of genitourinary cancer appears warranted. [Table: see text]

Comprehensive genomic profiling of relapsed and refractory small cell neuroendocrine carcinoma of the urinary bladder.

350 Background: Small cell neuroendocrine carcinoma of the bladder (SCCB) is rare but aggressive form of genitourinary cancer that can arise de novo or in conjunction with urothelial carcinoma (UCB). Methods: DNA was extracted from 40 microns of FFPE specimen from 29 cases of relapsed, refractory and metastatic SCCB and 1,113 UCB. Comprehensive genomic profiling (CGP) was performed using a hybrid-capture, adaptor ligation based next generation sequencing assay to a mean coverage depth of > 503X. Tumor mutational burden (TMB) was calculated from a minimum of 1.11 Mb of sequenced DNA as previously described and reported as mutations/Mb. The results were analyzed for all classes of genomic alterations (GA), including base substitutions, insertions and deletions (short variants; SV), fusions, and copy number changes including amplifications (amp) and homozygous deletions. Results: 29 SCCB cases were confirmed on routine histology and featured positive IHC staining for chromogranin, synaptophysin or both. Patients had a mean age of 68.1 years (range 49-90 years) and 25 (86%) were male. At the time of CGP, 3 (10%) SCCB were Stage III and 26 (90%) were stage IV. The primary SCCB was used for sequencing in 14 (48%) of cases and a metastasis sample in 15 (52%). The 29 SCCB featured 2.86 GA/case.The genomics of SCCB differed significantly from UCB (Table). The most frequent clinically relevant GA in SCCB were RICTOR amp (21%) and PIK3CA (10%), BRCA1, HGF, FBXW7 and CCND2 SV (7% each). The relatively high TMB in SCCB (7% TMB > 20 mut/Mb and 28% TMB > 10 mut/Mb) is similar to that seen in UCB. No SCCB cases were MSI-high. ERBB2 and FGFR1 GA frequencies (both 3%) in SCCB were lower than in similarly studied UCB. Conclusions: SCCB differs in genomic landscape from UCB in having higher frequencies of TP53 and RB1 GA and lower frequencies of FGFR3 and ERBB2 GA. However, like UCB, SCCB shares the presence of multiple GA associated with potential responses to targeted therapies and high TMB associated with response to immune checkpoint inhibitor therapy. [Table: see text]