Germline and somatic mutational variants of Tunisian high grade serous ovarian cancer identified by next-generation sequencing

Olaparib, a poly (ADP-ribose) polymerase (PARP) inhibitor (PARPi), is approved as maintenance therapy for patients with advanced pancreatic cancer (PC) and a germline BRCA1 or BRCA2 pathogenic variant (PV). This investigator-initiated, single-arm phase II study assessed the role of the PARPi rucaparib as maintenance therapy in advanced PC with germline or somatic PV in BRCA1, BRCA2, or PALB2. Eligible patients had advanced PC; germline (g) or somatic (s) PVs in BRCA1, BRCA2, or PALB2, and received at least 16 weeks of platinum-based chemotherapy without evidence of platinum resistance. Chemotherapy was discontinued and patients received rucaparib 600 mg orally twice a day until progression. The primary end point was the progression-free survival (PFS) rate at 6 months (PFS6). Secondary end points included safety, ORR, disease control rate, duration of response, and overall survival. Of 46 enrolled patients, 42 were evaluable (27 gBRCA2, seven gBRCA1, six gPALB2, and two sBRCA2). PFS6 was 59.5% (95% CI, 44.6 to 74.4), median PFS was 13.1 months (95% CI, 4.4 to 21.8), and median overall survival was 23.5 months (95% CI, 20 to 27). The PFS at 12 months was 54.8%. ORR of the 36 patients with measurable disease was 41.7% (3 complete responses; 12 partial responses; 95% CI, 25.5 to 59.2), and disease control rate was 66.7% (95% CI, 49.0 to 81.4). Median duration of response was 17.3 months (95% CI, 8.8 to 25.8). Responses occurred in patients with gBRCA2 (41%, 11 out of 27), gPALB2 (50%, 3 out of 6), and sBRCA2 (50%, 1 out of 2). No new safety signals were noted. Maintenance rucaparib is a safe and effective therapy for platinum-sensitive, advanced PC with a PV in BRCA1, BRCA2, or PALB2. The finding of efficacy in patients with gPALB2 and sBRCA2 PVs expands the population likely to benefit from PARPi beyond gBRCA1/2 PV carriers.

Patients with pathogenic germline and somatic variants in DNA damage repair (DDR) genes may derive greater benefit with platinum-based chemotherapy in metastatic pancreatic ductal adenocarcinoma (PDAC). This study investigates the role of DDR genes as a predictive biomarker for response to first-line platinum chemotherapy with FOLFIRINOX in metastatic PDAC patients. Demographic, clinical, and pathologic variables were collected for patients with metastatic PDAC who received FOLFIRINOX as frontline treatment and who had germline and somatic genetic testing. Kaplan-Meier analysis of overall survival (OS) and progression free survival (PFS) were correlated to the presence of DDR pathogenic variants. Forty patients with metastatic PDAC met inclusion criteria. Germline genetic testing revealed germline pathogenic variants in DDR genes in 5 patients (12%), and somatic pathogenic variants in DDR genes in 4 patients (10%). Median PFS was significantly longer in patients with any (germline or somatic) pathogenic variant in DDR genes than in those without alterations 18.5 vs. 6.9 months (log-rank P=0.003). When restricted to the presence or absence of germline pathogenic variants in DDR genes, the median PFS was 18.5 vs. 7.4 months (log-rank P=0.005). The median OS for the entire cohort was 11.5 months was not statistically different between the two groups, however there were no deaths in the subgroup with germline pathogenic variants in DDR genes treated with frontline FOLFIRINOX. A subset of patients with metastatic PDAC and germline or somatic pathogenic variants in DDR genes have a statistically superior PFS when treated with the platinum containing regimen FOLFIRINOX. The role of DDR gene alterations as a predictive biomarker for FOLFIRINOX benefit should be further evaluated in prospective trials.

138 Background: HRR PVs can serve as predictive biomarkers and two PARP inhibitors are approved for metastasic CRPC (mCRPC) pts. Published data are predominantly focused on tissue-based assays, but obtaining tissue from mCRPC pts is problematic. In a large tissue based series (PROfound), 4047 mCRPC pts had tumor samples submitted for genomic testing but only 69% had interpretable results. No data were published from PROfound enumerating pts without available tissue to submit. Herein we assess frequency of PVs from selected HRR genes using a ctDNA assay. Methods: 292 mCRPC pts at Tulane Cancer Center were assessed for detectable HRR ctDNA changes using the Guardant 360 assay (which assesses the HRR genes BRCA1, BRCA2, and ATM). Results: 20/292 (6.8%) pts had a PV in ATM. However only 4/292 (1.4%) had > 1% mutant allelic fraction. Germline testing occurred in 18/20 of the ctDNA ATM PV pts and 0/18 had a germline PV. The PROfound series had 6.3% somatic PVs in ATM. 18/292 pts (6.2%) had a PV in BRCA2 and 12/292 (4.1%) had a mutant allelic fraction of > 1%. Germline testing was performed in 17/18 with BRCA2 ctDNA PVs and 9/17 had germline PVs. The PROfound series had 9.7% somatic BRCA2 PVs. BRCA1 PVs were detected in 6/292 (2.1%) pts and 3/292 (1%) had a mutant allelic fraction > 1%. 6/6 of the ctDNA PVs has germline testing and 1/6 had a BRCA1 PV. The PROfound series had 1.3% somatic PVs in BRCA1. Conclusions: Using ctDNA essay, it is feasible to measure PVs in only a small subset of HRR genes in mCRPC pts. These assays fail to detect deep deletions, a known and important mechanism of HRR gene loss. The ctDNA mutant allelic fractions are often low. The ability of ctDNA PVs using this assay to predict treatment effects are unknown.

5525 Background: NRG GY012 is a randomized, 3-arm phase II study, comparing olaparib (O) and the combination of cediranib and olaparib (CO) to the reference arm cediranib (C) for metastatic pre-treated, endometrial cancer (EC). The trial found a trend towards benefit for CO and no benefit for O compared to C. Archival tumor and prospective blood samples were collected for biomarker analysis. Methods: Targeted next-generation sequencing (BROCA-GO) was used to detect pathogenic variants (PV) and loss of heterozygosity (LOH) in DNA from paired blood and archival cancers. The LOH cut-off was identified at 11% for HRD based on testing ovarian cancers with known HRD. Plasma samples collected at baseline, cycle 2 day 1, and end-of-treatment were analyzed via multiplex ELISA for 25 angiogenic and inflammatory circulating protein biomarkers (Angiome); IL6 was of specific interest. Prognostic associations with PFS and OS were analyzed using proportional hazards models (PhM) stratified by histology and adjusted for treatment assignment. Predictive associations (PFS and OS) were analyzed using PhM stratified by histology and including main effects for both treatment assignment and biomarker group plus an interaction term. Results: In 97 patients (pts) with evaluable tumor, BROCA-GO identified 370 somatic PV; TP53 (61%) was the most commonly mutated gene. PV in homologous recombination repair (HRR) genes were identified in 5 cases (5%). Somatic PVs were identified in BRCA2, RAD51B and PALB2. 1 pt had a germline BRCA1 PV. 2 cases had somatic PV that might restore HRR: 1 case with a somatic BRCA2 PV had somatic PVs in CHD4 and TP53BP1; the TP53BP1 frameshift PV was present only in the recurrent and not primary cancer. LOH was available for 45 cases. LOH high occurred in 16 (35.6%) cases and was exclusive to EC with TP53 mutations (p=0.0003). LOH was not associated with outcome in any of the arms. For the circulating biomarker analysis (N=96), median IL-6 was 4pg/ml. IL-6 levels >4pg/ml were associated with increased risk of progression (HR: 1.59; 95% CI: (1.04-2.42); p-value=0.032). In predictive analyses, pts with IL-6 > 4 pg/ml receiving C or C+O had increased PFS (3.8 mo vs 1.9 mo) and OS (11.9 mo vs 5.7 mo) compared to pts receiving O, the interaction p value did not reach statistical significance. Conclusions: LOH high status was not associated with outcome to O. There were too few cases with HRR PVs to determine their relationship to PARPi response. The restriction of LOH high to cancers with TP53 mutation may suggest that genomic LOH in ECs correlates better with aneuploidy than with HRR function indicating that at least some biomarkers of PARPi response vary between tumor types. IL-6 levels were prognostic of PFS but were not predictive of either OS or PFS for pts receiving C compared to pts receiving O in this small study. Further analysis of the complete Angiome and integration with the BROCA-GO dataset are ongoing. Clinical trial information: NCT03660826 .

Background: Target sequencing of epithelial ovarian cancer (EOC) has been widely used in clinical to detect the status of BRCA1/2 and genes in homologous recombination repair (HRR) pathway. But there still lacks of systematic evaluation of HRR related gene mutation effect on clinical outcome. Methods: Totally 230 EOC patient is recruited and received OseqT panel sequencing including 12 HRR related genes, 5 mismatch repair related genes and 8 ovarian cancer related genes. All the patients received platinum-based chemotherapy. 25 of them received PARP inhibitor therapy. Their responses to the therapy, OS and PFS were collected for analysis. Results: We found that BRCA2 and BRCA1/2 mutation carriers (somatic and germline) had longer OS (p value: 0.016 and 0.028) and PFS (p value: 0.002, 0.006) than non-carriers, PTEN and MSH2 germline mutation carriers had longer PFS (p value: 0.038, 0.049) than non-carries. When we compared germline pathogenic carriers and non-pathogenic carriers on OS and PFS, there is significant difference in PALB2 (p value: 0.036, 0.015) and STK11 (0.001, 0.018), BRCA1 mutation did not affect survival time in both OS and PFS. Then we observed the response to platinum-based chemotherapy. We found that the carriers of germline pathogenic variants in BRCA1, BRCA1/2 and HRR related genes were significant related with better response (p value: 0.16, 0.042 and 0.048), If we combined germline and somatic pathogenic variants together, the p value of BRCA1, BRCA1/2 and HRR related genes were changed to 0.001, 0.009 and 0.001. Somatic status of those gene alone had no relationship with chemotherapy response.In the patients received treatment of PARP inhibitor Niraparib, carriers of germline and somatic pathogenic variant in BRCA1 and BRCA1/2 were more sensitive to Niraparib (p value: 0.18, 0.008), There was only 1 BRCA2 pathogenic carrier and no other HRR related gene pathogenic carrier in 25 patients. So, the sensitivity of BRCA2 and HRR-related gene mutation carriers were not calculated. Conclusions: In our cohort, BRCA2 and BRCA1/2 mutation carriers had longer OS and PFS than non-carriers. PTEN, MSH2, PALB2 and STK11 mutation status also had relationship with survival in some circumstances, BRCA1, BRCA1/2 and HRR-related genes could all be used to predict drug sensitivity, germline and somatic variant should be combined used to reach better performance. Citation Format: Lei Li, Kang Shao, Jianwei Zhang, Meng Liu, Kui Wu, Ming Wu. Evaluation of homologous recombination repair related gene mutation on survival and drug response in Chinese epithelial ovarian cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 659.

P3-09-05: Clinical outcome of patients with advanced triple negative breast cancer with germline and somatic variants in homologous recombination gene

We aimed to evaluate the prevalence of armadillo repeat-containing 5 (ARMC5) genetic defects in our cohort of bilateral adrenal incidentaloma (BAI) patients and to evaluate the possible existence of genotype-phenotype correlations. Cross-sectional study. Tertiary care center. 72 BAI patients. The following data have been collected: morning adrenocorticotropic hormone (ACTH) concentrations; cortisol levels after 1 mg overnight dexamethasone suppression test (F-1mgDST); urinary free cortisol (UFC) levels; diameter of the adrenal masses; and the association with overweight/obesity, arterial hypertension, diabetes mellitus, dyslipidemia, cardiovascular events, unrelated neoplasia, osteoporosis, thyroid nodular disease, and primary hyperparathyroidism. A search for ARMC5 germline and somatic pathogenic variants was performed in all patients and in the adrenal tissue of patients operated on, respectively. The prevalence of germline ARMC5 pathogenic variants among patients with mild autonomous cortisol secretion (MACS+, defined as F-1mgDST > 1.8 µg/dL) was 18.8%. No germline pathogenic variants were detected in patients without MACS. Moreover, somatic ARMC5 pathogenic variants were also found in the adrenal tissue of six patients without germline ARMC5 variants. The F-1mgDST levels >5 µg/dL predicted with a poor sensitivity but a 90.5% specificity in identifying the presence of ARMC5 germline pathogenic variants. We did not find any clinical parameter predictive of the ARMC5 mutation presence. In MACS+ BAI patients, germline ARMC5 gene pathogenic variants are frequent. Further studies are needed to elucidate the pathophysiological role of somatic ARMC5 pathogenic variants on adrenal tumor development in otherwise wild-type (WT) patients.

The impact of an educational and information systems initiative on somatic BRCA testing rates in patients with high grade serous tubo-ovarian cancer in Western Australia

ObjectiveTo determine the frequency of germline and somatic pathogenic BRCA1 and BRCA2 variants in patients with high‐grade serous ovarian cancer tested by next‐generation sequencing (NGS), with the aim of defining the best strategy to be implemented in future routine testing.DesignNational retrospective audit.SettingThe All Wales Medical Genomics Service (AWMGS).PopulationPatients with high‐grade serous ovarian/fallopian tube/peritoneal cancer referred by oncologists to the AWMGS between February 2015 and February 2021 for germline and/or tumour testing of the BRCA1 and BRCA2 genes by NGS.MethodsAnalysis of NGS data from germline and/or tumour testing.Main outcome measuresFrequency of BRCA1 and BRCA2 pathogenic variants.ResultsThe overall observed germline/somatic pathogenic variant detection rate was 11.6% in the 844 patients included in this study, with a 9.2% (73/791) germline pathogenic variant detection rate. Parallel tumour and germline testing was carried out for 169 patients and the overall pathogenic variant detection rate for this cohort was 14.8%, with 6.5% (11/169) shown to have a somatic pathogenic variant. Two BRCA1 dosage variants were found during germline screens, representing 2.0% (2/98) of patients with a pathogenic variant that would have been missed through tumour testing alone.ConclusionsParallel germline and tumour BRCA1 and BRCA2 testing maximises the detection of pathogenic variants in patients with high‐grade serous ovarian cancer.Tweetable abstractParallel germline and tumour testing maximises BRCA pathogenic variant detection in ovarian cancer.

1/#337 Molecular classification of endometrial cancers using an integrative DNA sequencing panel

For advanced biliary tract cancer (BTC) patients with BRCA pathogenic variants who have failed first-line treatment, the optimal treatment strategy remains to be established. Olaparib, the first FDA-approved poly adenosine diphosphate-ribose polymerase inhibitors (PARPi), is commonly utilized in clinical practice for breast, ovarian, prostate, and pancreatic cancers that harbor germline or somatic BRCA pathogenic variants through a mechanism known as "synthetic lethality". However, the proportion of BTC patients with BRCA pathogenic variants is relatively low, estimated at approximately 1%-7% of all BTC cases, leading to inconclusive evidence regarding the efficacy of targeted therapy with PARPi for these patients. We presented a case of a patient with advanced intrahepatic cholangiocarcinoma (iCCA) harboring dual somatic homologous recombination repair (HRR) gene pathogenic variants, specifically BRCA1 and PALB2, who achieved PR lasting approximately 7months following salvage treatment with olaparib. We considered that the BTC population with dual HRR pathogenic variants, which include a BRCA pathogenic variant, might represent an advantageous cohort for olaparib treatment. Furthermore, in addition to BRCA pathogenic variant, PALB2 pathogenic variant may potentially serve as the next clinical predictive target for PARP inhibitors in the BTC population. A systematic summary and analysis of existing studies on BTC patients with pathogenic variants indicate that these patients might derive benefits from olaparib; however, further validation in a larger cohort is necessary.

Background: The Ashkenazi Jewish (AJ) population exhibits a distinctive mutation profile in BRCA1 and BRCA2 (BRCA1/2), characterized by 3 common founder mutations: BRCA1 185delAG, BRCA1 5382insC, and BRCA2 6174delT. These 3 mutations are associated with 10% of invasive breast cancer (BC) cases among AJ women. However, the frequency of non-founder pathogenic variants in BRCA1/2 and other BC-related genes in AJ women with BC remains unclear. Methods: This retrospective study included AJ patients diagnosed with stage I-II human epidermal receptor growth factor 2 negative BC between 2004-2022 at the Weill Cornell Breast Center. We collected clinicopathological characteristics and genetic information to determine the frequency of predisposing mutations in BC and non-BC related genes in AJ patients with early BC. We also analyzed the clinicopathological characteristics and outcomes of patients with and without germline mutations in these genes. Results: The study included 232 self-identified AJ patients, with 98% being females. The median age at BC diagnosis was 62 years (IQR: 50-70). Stage I and II cancers accounted for 68% and 32% of cases, respectively. Hormone receptor positivity (HR+) was observed in 71% of patients, while 29% had triple-negative tumors. Genetic testing was performed on 88% (n=203) of the patients, while 5% of patients declined to undergo genetic testing. Among the tested patients, 12% (n=25/203) had pathogenic variants in BRCA1 or BRCA2, with 44% and 16% of these corresponding to the BRCA1 and BRCA2 founder mutations, respectively. Testing beyond BRCA1/2 genes was conducted on 154 patients, and only 6% (n=9/154) were found to have pathogenic variants in CHEK2, while no mutations were detected in other prevalent BC-related genes, including PALB2 and ATM. Fourteen-percent of patients had pathogenic mutations in other genes including APC, CFTR, FH, DIS3L2, FANCC, MUTYH, NF1 and VHL. The frequency of pathogenic BRCA1/2 variants was inversely proportional to the age at BC diagnosis: 50% (n=8/16), 21% (n=8/39), 15% (n=6/40), and 3% (n=3/108) of patients diagnosed at age < 40, 40-49, 50-59, and >60 years, respectively, had a pathogenic variant in either BRCA1 or BRCA2. The frequency of founder mutations varied according to age at diagnosis: 63%, 75%, 17%, and 100% for patients aged < 40, 40-49, 50-59, and >60 years, respectively. Patients with BRCA1/2 mutations exhibited higher-risk clinicopathological features compared to those without mutations, including a higher proportion of high histological grade (88%), and triple-negative tumors (76%). Mastectomy was the primary surgical treatment for 56% and 23% of patients with and without BRCA1/2 mutations, respectively. No difference in disease-free survival was found between patients with and without BRCA1/2 mutations with a median follow up of 3 years (IQR: 1-4). Conclusions: In our cohort, 17% of AJ patients with early BC carried a pathogenic variant in a BC-related gene, with BRCA1/2 being the most commonly affected genes. The proportion of pathogenic variants in BRCA1/2 showed an inverse correlation with the age at BC diagnosis, reaching up to 50% in patients diagnosed under the age of 40. These findings contrast with the lower prevalence of pathogenic variants in BRCA1/2 (38%) reported in the existing literature for this age group. Additionally, 8% of patients had pathogenic variants in other tested cancer genes carrying a genetic predisposition to colorectal cancer (CRC). These findings contribute to our understanding of the genetic landscape of early BC in the AJ population and emphasize the importance of comprehensive genetic testing, particularly among young patients. These results also suggest the need for earlier and more frequent CRC screening in a population of BC patients that may not be adhering to recommended guidelines. Furthermore, our study provides insight into how this genetic landscape may vary when analyzing late-stage BC in women of AJ heritage. Citation Format: Laura Munoz Arcos, Eleonora Nicolò, Maira Pires, Letizia Pontolillo, Leticia Varella, Tessa Cigler, Eleni Andreopolu, Anne Moore, Ashley Schreier, Carlos Munoz-Zuluaga, Lisa Newman, Georgia Syrnioti, Massimo Cristofanilli. Genetic Landscape of Early Breast Cancer in an Ashkenazi Jewish Cohort [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-08-11.

Exomic and epigenomic analysis of pulmonary blastoma

e17116 Background: Molecular characterization of prostate cancer (PCa) has allowed development in targeted therapies design; with molecular imaging as PSMA-PET, they both determine precision oncology and personalized medicine. Currently, genomic advancements have lead to mayor prognostic and predictive implications in oncologic outcomes, aim in this study was to evaluate and describe PSMA-PET quantitative parameter patterns in de novo metastatic hormonosensitive prostate cancer (mHSPC) and the associations with somatic pathogenic variants. Methods: We conducted a retrospective analysis of 45 patients referred to the nuclear medicine’s department in Mexico’s National Cancer Institute for a staging PSMA-PET/CT, with confirmed PCa histopathological results and with new generation sequency (NGS) testing of the primary tumour. Results: 28.89% (n=13) of patients had confirmed pathogenic (or likely pathogenic) variant (PV) mutations in HRR or TS genes; 35.56% (n=16) had variants of unknown significance (VUS) mutations, and 35.56% (n=16) of patients had a negative NGS test. PV and VUS detected are described in table 1, Coexisting PV (≥2) were found in 23% and 37.5% in VUS group. Differences between group 1 and 3 were statistically significant (Mann Whitney’s U p=0.0056). In the mutational status analysis, group 1 and group 2 did not have any significant difference in overall survival ( p=0.731 ); opposed to statistical results from group1 and 2 (altogether) compared to group 3 ( p=0.055 ). We defined TTV cutoff value at 94 ml, for worse overall survival by ROC curves, and was used to stratify patients according to TTV (>94 ml vs <94 ml) and mutational status (VP carriers + VUS carriers vs non-mutated); where VP and VUS carriers with >94 ml TTV exhibited a worse molecular and clinical prognostic behavior, resulting in a markedly decreased overall survival (p =0.0218 ) Log-rank Mantel Cox’s. Conclusions: Mutations in the HRR gene are associated with increased metabolic substrate requirements for DNA base pairs as a compensatory mechanism for the effects of such mutations. Folate hydrolase and glutamate carboxypeptidase are core functions of PSMA and play a role as a molecular marker in cellular adaptive mechanisms to genomic alterations. Our findings suggest that the integration of molecular imaging and genomic profiling has an impact on overall survival. Mutational and PSMA SUVmax characteristics. Group PV carriers (Group 1) VUS carriers (Group 2) Non-mutated (Group 3) SUVmax (Median) SUVmax (Range) 16.5 (8.2-39.9) 9.3 (3.1-28.86) 9.75(4.1-16.6) Genes p53(n=4) 30.8% ATM 18.75%(n=3) CHECK2(n=2) 15.4% p53 12.5%(n=2), ATM(n=2) 15.4% RAD54D 6.25% (n=1) FANCA(n=1) 7.7% CHECK2 6.25% (n=1) RADB51(n=1) 7.7% CDK12 6.25% (n=1) FANCL 6.25% (n=1) BRCA1 6.25% (n=1)

Simple SummaryThe biology of thymic epithelial tumours (TETs), including thymomas and thymic carcinomas, and particularly the extent of molecular dysregulation, is poorly understood. Through next-generation sequencing of 15 genes implicated in common solid tumours in 53 TETs, we found a larger number of single nucleotide variants (SNVs) in thymic carcinomas than thymomas. About 30% of thymic carcinomas had at least one somatic pathogenic gene variant in TP53, ERBB2, KIT, or KRAS, whereas variants of uncertain clinical significance in KIT, ERBB2, and FOXL2 were found exclusively in thymomas. The presence of somatic pathogenic variants was non-significantly associated with shorter disease-free survival in thymic carcinoma patients. No somatic pathogenic or likely pathogenic SNV was found in thymomas. Importantly, we also evaluated germline SNVs, adding to the number of known genetic alterations in TETs and thereby enhancing our molecular understanding of these neoplasms.A better understanding of the molecular pathogenesis of thymic epithelial tumours (TETs) could revolutionise their treatment. We evaluated thymomas and thymic carcinomas by next-generation sequencing (NGS) of somatic or germline single nucleotide variants (SNVs) in genes commonly mutated in solid tumours. In total, 19 thymomas and 34 thymic carcinomas were analysed for nonsynonymous SNVs in 15 genes by targeted NGS (reference genome: hg19/GRCh37). Ten SNVs in TP53 (G154V, R158P, L194H, R267fs, R273C, R306 *, Q317 *), ERBB2 (V773M), KIT (L576P), and KRAS (Q61L) considered somatic and pathogenic/likely pathogenic were detected in 10 of 34 (29.4%) thymic carcinomas. No somatic SNVs confirmed as pathogenic/likely pathogenic were found in thymomas. Rare SNVs of uncertain or unknown functional and clinical significance, to our knowledge not reported previously in TETs, were found in ERBB2 (S703R), KIT (I690V), and FOXL2 (P157S) in 3 of 19 (16%) thymomas. The most frequent germline SNVs were TP53 P72R (94% TETs), ERBB2 I655V (40% TETs), and KIT M541L (9% TETs). No significant difference in median disease-free survival (DFS) was found between thymic carcinoma patients with and without pathogenic SNVs (p = 0.190); however, a trend toward a longer DFS was observed in the latter (16.0 vs. 30.0 months, respectively). In summary, NGS analysis of TETs revealed several SNVs in genes related to the p53, AKT, MAPK, and K-Ras signalling pathways. Thymic carcinomas showed greater genetic dysregulation than thymomas. The germline and rare SNVs of uncertain clinical significance reported in this study add to the number of known genetic alterations in TETs, thus extending our molecular understanding of these neoplasms. Druggable KIT alterations in thymic carcinomas have potential as therapeutic targets.