Characterization of genomic alterations, tumor mutational burden and PDL1 expression in 181 Chinese hepatocellular carcinomas.

726 Background: NF2 genomic alterations (GA) have been associated with aggressive behavior in RCC. Methods: FFPE tissues from 1,386 clear cell (ccRCC), 307 papillary (pRCC), 72 chromophobe (chRCC), 145 sarcomatoid (sRCC), 54 collecting duct (cdRCC),37 medullary (medRCC) and 134 unclassified (nosRCC) underwent hybrid-capture based CGP to evaluate all classes of genomic alterations (GA). Tumor mutational burden (TMB) was determined on up to 1.1 Mbp of sequenced DNA and MSI was determined on 114 loci. PD-L1 expression was determined by IHC (Dako 22C3). Results: 140 (7%) RCC featured NF2 GA which were predominantly short variant (SV) mutations. Gender and age were similar with male preponderance in all histologic subtypes. NF2 GA frequency was highest in cdRCC (20%) and sRCC (19%) and lowest in ccRCC (3%). The medRCC at 5% NF2 GA and chRCC at 0% NF2 GA were not further evaluated. VHL and PBRM1 GA were significantly more frequent in NF2 altered ccRCC than all other RCC (P < 0.001). Other mTOR pathway GA were uncommon. Potentially targetable kinase GA in NF2-mutated RCC included BRAF (2% of ccRCC), EGFR (3% of pRCC), ERBB3 (4% of sRCC) and PIK3CA (9% of cdRCC). No NF2 mutated RCC featured MSI -high status and both TMB and PD-L1 expression levels were extremely low in all subsets with exception of high PD-L1 staining in sRCC tumors. Conclusions: cdRCC, sRCC, pRCC and nosRCC are enriched in NF2 GA. Low PBRM1 GA, TMB and MSI- high predict resistance to immunotherapy in NF2 mutated RCC although the high PD-L1 expression in sRCC is noteworthy.[Table: see text]

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Association of tumor mutational burden in cutaneous squamous cell carcinoma with genomic alterations in Notch family receptors.

Journal of Clinical Oncology ◽

10.1200/jco.2017.35.15_suppl.e13031 ◽

2017 ◽

Vol 35 (15_suppl) ◽

pp. e13031-e13031

Author(s):

Eric Allan Severson ◽

Shakti Ramkissoon ◽

Sugganth Daniel ◽

Jo-Anne Vergilio ◽

Laurie M. Gay ◽

...

Keyword(s):

Squamous Cell Carcinoma ◽

Cell Carcinoma ◽

Family Member ◽

Squamous Cell ◽

Cutaneous Squamous Cell Carcinoma ◽

Genomic Alterations ◽

Functional Impact ◽

Mutational Burden ◽

Tumor Mutational Burden ◽

Frameshift Indels

e13031 Background: In Cutaneous Squamous Cell Carcinoma (cSqCC), Notch1, Notch2, and Notch3 have been identified as tumor suppressors with a high rate of inactivating mutations early in cSqCC pathogenesis. Despite the high frequency of alterations, the biologic and therapeutic implications of Notch genomic alterations (GAs) in cSqCC are incompletely understood. Methods: 232 FFPE samples of cSqCC were evaluated by comprehensive genomic profiling (CGP) of 315 genes and analyzed for all classes of GAs, with diagnoses confirmed by central pathology review. Notch GAs with unknown functional impact were excluded. Tumor mutational burden (TMB) was calculated from 1.11 Mb of sequenced DNA and reported as mutations/Mb. Results: The cohort of 232 samples was 78% male and 22% female, aged from 17 to 88, with confirmed metastatic disease in 32% of cases. 115 (50%) samples had a Notch family member GA with a known or predicted functional impact. 96 cases had Notch1 GAs, 43 cases had Notch2 GAs, and 14 cases had Notch3 GAs with 40 cases having GAs in multiple Notch family members. These mutations were 41% missense, 34% nonsense, 15% splice site, 9% frameshift indels, and 1% non-frameshift indels alterations. Patients with Notch GAs were significantly older (median 70 years old vs median 64, p < 0.01). TMB was increased among samples with Notch GAs (median TMB of 63 mutations/mb versus 20 mutations/mb, p < 1x10-6), with similar differences for primary and metastatic samples. Cases with Notch GAs had more total GAs per case (mean 10.4 vs 7.4, p < 1.5x10-10); however, the top co-mutated genes were the same (TP53, CDKN2A, FAT1, MLL2). Both groups had a high proportion of C- > T/G- > A transitions, consistent with UV damage; however, the proportion was higher in cases with Notch GAs (median 83% vs 80%) - a difference seen in primary and metastatic samples. Conclusions: 50% of cSqCC cases had a Notch family member loss of function GA, which was associated with increased TMB in the primary and metastatic setting. With pre-clinical models and case studies showing responses to PD-1 inhibitors in cSqCC, further investigations are warranted into the associations of Notch GAs with mutational burden and response to immunotherapy.

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Characterization of the genetics of mucosal melanoma in patients treated with immunotherapy.

Journal of Clinical Oncology ◽

10.1200/jco.2019.37.15_suppl.9556 ◽

2019 ◽

Vol 37 (15_suppl) ◽

pp. 9556-9556

Author(s):

Elizabeth Iannotti Buchbinder ◽

Jason L. Weirather ◽

Michael P. Manos ◽

Ryan C. Brennick ◽

Patrick Alexander Ott ◽

...

Keyword(s):

Checkpoint Inhibitors ◽

High Response Rate ◽

Mucosal Melanoma ◽

Rare Type ◽

Kit Mutation ◽

Mutational Burden ◽

Tumor Mutational Burden ◽

Melanoma Patients ◽

Mechanistic Basis

9556 Background: Mucosal melanomas can be effectively treated with checkpoint inhibitors, although the response rates are lower than those observed for melanomas arising in cutaneous sites. The mechanistic basis for the lower efficacy of immunotherapies in mucosal melanoma has been suggested to be related to their lower mutational burden. However, there has been limited characterization of the genetics in this melanoma subtype. Methods: Tumor genotyping was performed on all mucosal melanoma patients seen within the Dana Farber Cancer Institute from 2011 until the present by Oncopanel analysis. Results: We identified a total of 57 mucosal melanoma patients whose tumors had been genotyped. Of these 42 received immunotherapy and had response data available. Within the cohort of mucosal melanoma patients, 37.3% had durable clinical benefit (DCB) to their first line of IO therapy. These patients had an average mutational burden/megabase of 6.41 (95% CI 3.53-11.01) but tumor mutational burden did not correlate with response in this cohort. The pattern of mutations in mucosal melanomas was distinct from cutaneous melanomas, as the most frequent mutations were in SF3B1, ATRX, KIT and NF1 genes. Patients with KIT aberrations had a higher DCB rate compared patients with wildtype KIT (73 vs. 33%). In addition, there were several genetic differences observed based upon the site of origin of the mucosal melanoma. A higher rate of SF3B1 mutations was observed in patients with melanoma of anal/rectal origin while patients with vulvar/vaginal melanoma had higher rates of ATRX mutations, which frequently correlated with p53 ( TP53) mutations. Conclusions: This analysis is one of the first to look at genetic patterns in a large cohort of a relatively rare type of melanoma and correlate with response. Our findings confirm the low mutational burden observed in mucosal melanoma despite the high response rate observed in these patients. In addition, this study uncovered a higher rate of response to immunotherapy in mucosal melanoma patients with a KIT mutation.

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Abstract 3394: CGP identifies largely non-overlapping high tumor mutational burden and HRD genomic alterations in 721 clinically advanced prostate acinar adenocarcinoma cases

10.1158/1538-7445.am2017-3394 ◽

2017 ◽

Author(s):

Ninad Dewal ◽

Yuting He ◽

Richard J. Lee ◽

Alexa B. Schrock ◽

Jon Chung ◽

...

Keyword(s):

Genomic Alterations ◽

Mutational Burden ◽

Tumor Mutational Burden

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Association between homologous recombination deficiency and tumor mutational burden in lung cancer.

Journal of Clinical Oncology ◽

10.1200/jco.2020.38.15_suppl.e21043 ◽

2020 ◽

Vol 38 (15_suppl) ◽

pp. e21043-e21043

Author(s):

Yong Jiang ◽

Shiying Dang ◽

Li Yang ◽

Yin Han ◽

Yongshen Zhang ◽

...

Keyword(s):

Lung Cancer ◽

Homologous Recombination ◽

Gene List ◽

Genomic Alteration ◽

Missense Mutations ◽

Coding Region ◽

Genomic Alterations ◽

Homologous Recombination Deficiency ◽

Mutational Burden ◽

Tumor Mutational Burden

e21043 Background: Homologous recombination (HR) is an important repair method for DNA double-strand damage. HR is involved with complex signaling pathways and multiple steps, including BRCA1/2. Homologous Recombination Deficiency (HRD) can be caused by the loss of function of BRCA1/2 proteins due to gene mutation. Tumor mutational burden (TMB) was indicated to involved with HRD, which is critical to the guidance of immunotherapy. Methods: Patients available with tumor specimen genomic testing for lung cancer were enrolled in this study. The sequencing library was captured using a 605-gene panel. Homologous recombination (HR)-related gene list included 102 genes. Genomic alterations of HR-related genes were assessed by next-generation sequencing assay, including nonsense, nonstop, frameshift, splice site, damaging missense mutations in somatic variants and pathogenic germline variants. Then, TMB was calculated by dividing the total number of mutations counted by the size of the coding region. Results: A total of 741 patients was enrolled and 182 of them (25.6%) had at least one genomic alteration of the HR genes. The top mutant HR genes included ATM (4.1%), DNMT3A (2.8%), ATR (1.8%), CHEK2 (1.5%), BRCA2 (1.5%), ABL1 (1.4%), FANCA (1.2%), RIF1 (1.1%), FANCI (1.1%), RAD50 (0.9%), BRCA1 (0.9%), and MRE11A (0.9%). The most common mutational type was missense mutation (69.2%), followed by frameshift (15.6%), and nonsense mutation (15.2%). The median age was 62 in the HRD group (age < 45:5.4%, 45-65:59.6%, > 65:34.9%) compared to 60 in the rest of the patients (age < 45:11.3%, 45-65:61.3%, > 65:27.4%). There were overall 57.5% males and 42.5% females in terms of gender. HRD group had a significantly higher rate than Non-HRD group in males (72.1% vs 52.8%, p < 0.01). The occurrence of HRD mutations was significantly correlated with a high level of TMB (p < 0.01). The median TMB of HRD group (7.9 muts/Mb, 95%CI:7.1-9.2 muts/Mb) was significantly higher than that of Non-HRD group (3.8 muts/Mb, 95%CI:3.3-4.2 muts/Mb). In addition, the upper quantile value (7.5 muts/Mb) was used to identify patients with high TMB. HRD group had a significantly higher rate of TMB-high patients than Non-HRD group (51.1% vs 17.0%, p < 0.01). Conclusions: Our study demonstrated genomic alterations of the HR genes in about one fourth’s lung cancer. Besides, there was a significant positive correlation between HRD mutations and TMB level. The significance of HRD genomic mutation on predicting the efficacy of immunotherapy deserves further study.

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