RET Mutations Research Articles

Lymph node metastasis in hereditary medullary thyroid cancer is independent of the underlying RET germline mutation

Although the onset of hereditary medullary thyroid cancer (MTC) depends on mutational risk, the impact of that risk on lymph node metastasis is unclear.Included in this investigation were 387 carriers of RET germline mutations with node-negative MTC (201 carriers) or node-positive MTC (186 carriers).Age at thyroidectomy increased significantly from highest (p.Met918Thr; 45 carriers), high (p.Cys634Arg/Gly/Phe/Ser/Trp/Tyr; 138 carriers) and moderate-high risk (p.Cys609/611/618/620Arg/Gly/Phe/Ser/Trp/Tyr; 93 carriers) to low-moderate risk (p.Glu768Asp, p. Leu790Phe, p. Val804Leu/Met, p. Ser891Ala; 111 carriers).In contrast, tumor progression to lymph node metastasis was similar, taking 8.6–9.1 years with moderate risk mutations and 13.6–14.5 years with high and highest risk mutations. Primary tumor size across the mutational risk spectrum changed little, measuring 18.1–22.1 mm with and 2.7–7.3 mm without lymph node metastasis.Because the biological behavior of hereditary MTC is similar after disease onset, equal treatment of comparable tumors is warranted regardless of the underlying RET mutation.

1178P Impact of comprehensive genomics profiling on treatment management of patients with advanced neuroendocrine neoplasms

Molecular genomic analyses are widely used in oncology but experience in advanced neuroendocrine neoplasms (NENs) is still limited. We have analyzed the sensibility to detect genomic aberrations in advanced NENs and the potential impact in the treatment decision process. We selected the last correlative 100 patients with advanced NENs in which next-generation sequencing (NGS) analyses were performed. Two different NGS techniques were used on formalin fixed paraffin embedded archival tumor samples: amplicon-seq for detection of DNA mutations and nanostring n-counter for fusions and copy number alterations. We analyzed 37 G1/2 gastroenteropancreatic (GEP) neuroendocrine tumors (NETs), 30 G3 GEP NENs, 21 medullary thyroid cancers (MTC) and 12 G1/G2 NETs of other locations. Genomic alterations were identified in 81.5% of G3 NENs including potentially targetable mutations in KRAS (50%), BRAF (27%), FGFR1 (7%), AKT1/2 (6%), BRCA2 (3%) and ERBB3 (3%). Mutations in RET were detected in 48% of MTC. However, few genomic mutations were identified in G1/G2 NETs (GEP & others) suitable to be treated with targeted agents, including KRAS (6%), FGFR3 (4%), and 1 reported mutation (2%) in each of the following genes of particular interest: FGFR2, ERBB2, PIK3CA and NRAS. NGS analyses may open new treatment options in advanced G3 NENs and are also mandatory upfront in advanced MTC to guide treatment with selective RET inhibitors in current development. However, the rentability of NGS in G1/G2 NETs is clearly lower and should be used in refractory setting or for investigational purposes.

Management of medullary thyroid carcinoma

: Medullary thyroid carcinoma (MTC) is a rare malignancy arising from parafollicular C-cells and accounts for 3–10% of all thyroid malignancies. MTC occurs mostly as a sporadic disease, but in at least 30% of cases is hereditary, caused by RET germline mutations. In this setting, different germline RET mutations lead to distinct clinical phenotypes of hereditary MTC such as familial MTC and multiple endocrine neoplasia 2A and 2B. RET genetic screening should be performed in all new discovered cases of MTC since about 4–10% of patients with apparently sporadic MTC have RET germline mutations and therefore an inheritable disease. Calcitonin (CT) is the most reliable marker of MTC for both diagnosis and follow-up after thyroidectomy. In sporadic MTC, a routine determination of CT in patients with nodular goiter has been correlated to a lower rate of advanced tumor stages. Surgery is the only curative treatment. Since the relatively high risk of multifocal and bilateral disease and the early spread to cervical lymph nodes, total thyroidectomy and central neck lymph node dissection is the standard initial treatment. Lateral neck lymph node dissection might be considered according to imaging results and CT levels. The potential benefit of neck reiterative surgery for persistent or recurrent MTC should be balanced against the increased surgical morbidity in a scarred operative field. The treatment of locally advanced MTC that is not amenable to surgery or metastatic MTC benefits of tyrosine kinase inhibitors that have shown some effects on disease progression. External radiotherapy and cytotoxic chemotherapy have demonstrated little benefit. Prognosis strictly depends on stage of disease at diagnosis, with lower survival and cure rate for stage IV disease. The purpose of this review is to describe the management and treatment of patients with MTC, focusing on biochemical and imaging diagnostic tools, preoperative work-up, treatment and prophylactic surgery for hereditary variants.

CD133 Expression in Medullary Thyroid Cancer Cells Identifies Patients with Poor Prognosis.

The identification of markers able to determine medullary thyroid cancer (MTC) patients at high-risk of disease progression is critical to improve their clinical management and outcome. Previous studies have suggested that expression of the stem cell marker CD133 is associated with MTC aggressiveness. To evaluate CD133 impact on disease progression in MTC and explore the regulatory mechanisms leading to the upregulation of this protein in aggressive tumors. We compiled a series of 74 MTCs with associated clinical data and characterized them for mutations in RET and RAS proto-oncogenes, presumed to be related with disease clinical behavior. We found that CD133 immunohistochemical expression was associated with adverse clinicopathological features and predicted a reduction in time to disease progression even when only RET-mutated cases were considered in the analysis (log-rank test P < 0.003). Univariate analysis for progression-free survival revealed CD133 expression and presence of tumor emboli in peritumoral blood vessels as the most significant prognostic covariates among others such as age, gender, and prognostic stage. Multivariate analysis identified both variables as independent factors of poor prognosis (hazard ratio = 16.6 and 2; P = 0.001 and 0.010, respectively). Finally, we defined hsa-miR-30a-5p, a miRNA downregulated in aggressive MTCs, as a CD133 expression regulator. Ectopic expression of hsa-miR-30a-5p in MZ-CRC-1 (RETM918T) cells significantly reduced CD133 mRNA expression. Our results suggest that CD133 expression may be a useful tool to identify MTC patients with poor prognosis, who may benefit from a more extensive primary surgical management and follow-up.

Abstract 5973: GIPC2 is a candidate tumor suppressor gene in sporadic pheochromocytoma

Abstract Pheochromocytoma (PCC) is a rare endocrine tumor of the chromaffin cells in adrenal medulla or the paraganglia. Currently about 60% of PCCs can be explained by germline or somatic mutations in well-established susceptibility genes such as RET, VHL and SDHB, while for the remaining, mainly sporadic cases the pathogenesis is still unclear. We explored the molecular basis of these PCCs by analyzing 22 sporadic adrenal PCCs, using SNP6.0 arrays to identify minimal region of the most common chromosomal loss, and expression profiling to identify genes with suppressed expression relative to normal medulla. Here we report the identification of GIPC2, a gene located at 1p31.1 encoding a PDZ domain containing adaptor protein with preferential expression in adrenal, as a putative tumor suppressor gene for sporadic PCC. In a cohort of 55 sporadic PCCs, 38 were found with reduced genomic copy number of GIPC2, with accompanying reduced expression of mRNA. Much reduced or loss of GIPC2 protein expression in tumor tissues was confirmed with Western blot or immunostaining. No GIPC2 mutations were found in the cohort but significant promoter hypermethylation was demonstrated using MassARRAY EpiTYPER assay and methylation-specific PCR. The GIPC2 protein was expressed mostly in the nucleus. With GIPC2 overexpression or siRNA knockdown in both PCC derived cell lines (rat PC12 or hPheo, a cell line derived from human PCC) and primary rat adrenal chromaffin cells (ACC), we showed that GIPC2 suppressed cell proliferation by inducing cyclin kinases such as p27, and by suppressing the activation of MAPK/Erk pathways without affecting pAKT or mTOR pathways. PC12 cells stably overexpressing GIPC2 failed to develop tumor in nude mice. To explore the molecular mechanism of GIPC2 in cell cycle regulation, we searched for its interaction proteins in 293T cells via mass spectrometry and identified NONO, a nucleoprotein with a known role in regulating cell cycle. Reciprocal interaction between GIPC2 and NONO was demonstration in PC12 or hPheo cells in vivo using immune-IP or FRET. We showed that knockdown of NONO blocked GIPC2-mediated p27 up-regulation. Furthermore both GIPC2 and NONO regulated p27 promoter through the same DNA binding site and a GGCC box was significant for GIPC2-regulated p27 promoter activity through NONO. Finally, we found that PCC-causing mutations in RET and SDHB, but not VHL, genes could lead to ACC proliferation and p27 downregulation via down-regulating GIPC2. In summary, our study indicates that GIPC2 acts as a candidate tumor suppressor gene in sporadic pheochromocytomas and regulates cell cycle gene p27 through NONO. Our results provide a new insight into the molecular mechanism of sporadic PCCs. Citation Format: Yeqing Dong, Zhengguang Guo, Chengyan Fan, Zhi Zheng. GIPC2 is a candidate tumor suppressor gene in sporadic pheochromocytoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5973.

Abstract 1317: RET aberrations in Chinese solid tumor patients: Next-generation sequencing of 10194 patients

Abstract Purpose: RET is an emerging oncogenic target showing promise in phase I/II clinical trials, but the comprehensive genomic landscape of RET aberrations across multiple cancers has had limited exploration. Experimental Design: We interrogated the molecular portfolio of 10194 patients with diverse cancers for the presence of RET aberrations using targeted next-generation sequencing (NGS) of 450 genes panel (OrigiMed, Shanghai). Results: Among various cancer types, RET aberrations were identified in 234 cases (2.3%, 234/10 194), with mutations being the most common alteration (62.4%, 146/234), followed by fusions (19.2%, 45/234), amplifications (13.2%, 31/234), and rearrangements (5.1%, 12/234). The proportion of RET mutations in papillary thyroid carcinoma, lung adenocarcinoma, colorectal adenocarcinoma, small cell lung cancer, and other subtypes was 28.6%, 4.2%, 3.6%, 3.0%, and 16.5% respectively. Most patients had coexisting aberrations in addition to RET anomalies (73.5%, 172/234), with the most common being in TP53-associated genes (40.2%, 94/234), the Wnt signaling pathway (39.3%, 92/234), the HR signaling pathway (19.2%, 45/234), the PI3K signaling pathway (17.5%, 41/234), and MAPK effectors (16.2%, 38/234). All 172 patients harboring coexisting aberrations had distinct genomic portfolios. Conclusions: This study revealed RET aberrations in 2.3% of Chinese solid tumor patients. RET aberrations were detected more in papillary thyroid carcinoma, lung adenocarcinoma, colorectal adenocarcinoma, and small cell lung cancer. Most cases harbored actionable, albeit distinct, coexisting alterations, all of which may potentially contribute to more effective treatment options in the future. Citation Format: Chengzhi Zhou, Junhang Zhang, Zhuojian Shen, Hongbiao Wang, Yun Li, Minghui Wang, Qin Fu, Lin Zhang, Angen Liu. RET aberrations in Chinese solid tumor patients: Next-generation sequencing of 10194 patients [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1317.

RET gene mutation analysis and long-term clinical outcomes of medullary thyroid cancer patients.

Medullary thyroid carcinoma is a rare, potentially aggressive tumour, with relatively worse prognosis than well-differentiated thyroid cancer. We evaluated the long-term outcomes and prognosis of medullary thyroid carcinoma patients at a single institution in India and compared outcomes based on results of RET protooncogene mutation analysis. Data were retrieved through a prospectively maintained thyroid cancer database from 1998 to June 2019, and medullary thyroid carcinoma patients were recruited. RET gene mutation status (exon 10-16) was assessed. Patient with a minimum follow-up of 12 months was eligible to be part of the long-term outcome analysis. Out of 149 peripheral blood samples, 42 were positive for RET gene mutation (prevalence of 28.1%). The median follow-up duration was 48 months, ranging from 12 to 240 months. Long-term clinical outcomes of 113 patients were assessed. Two deaths were noted in this series. Both 5- and 10-year survival was cent per cent. Overall survival was 98.2% (97.3% in RET positive and 98.7% in RET negative group). Progression-free survival was 55.4% in total (60% in RET positive and 53.3% in RET negative group). No statistically significant difference was found between RET positive and RET negative groups concerning overall survival (P = 0.6011) and progression-free survival (P = 0.5140). Univariate analysis revealed high calcitonin (>10 pg/mL), stage IV disease, and presence of lymph nodal metastasis to be significant predictors of disease recurrence, however, multivariate analysis demonstrated the presence of lymph node metastases as the only significant predictor of recurrence (P = 0.0005). Medullary thyroid carcinoma patients had relatively favourable long-term outcomes. Long-term survival was similar irrespective of RET mutation status. Presence of lymph node metastases appeared to be the strongest predictor of overall and progression-free survival, followed by Calcitonin level and stage of the disease.

Genetic profile of non-small cell lung cancer (NSCLC): A hospital-based survey in Jinhua.

BackgroundWe describe the clinical features, genetic profile, and their correlation in NSCLC patients.MethodsA total of 256 Chinese patients with NSCLC were enrolled in this study. NGS‐based genomic profiling of major lung cancer‐related genes was performed on formalin‐fixed paraffin‐embedded tumor samples.ResultsOf 256 patients with NSCLC, 219 were adenocarcinoma and most of them were in the early stage. Among patients, 63.3% patients have more than two gene mutations. By analyzing variant allele frequency (VAF), we found that the median VAF has significant differences between squamous cell carcinoma and adenocarcinoma, as well as early stage and advanced stage. The frequency of mutations in EGFR, MET, and RET were significantly higher in nonsmokers than in smokers. Besides, Pearson correlation analysis found that ALK, BRAF, and MET mutations had a strong correlation with age. Notably, higher frequencies of ALK and BRAF alterations were associated with younger age, while more frequent MET mutations appear in the patients at age 55 or older.ConclusionMore unique features of cancer driver genes in Chinese NSCLC were identified by next‐generation sequencing. These findings highlighted that it is necessary to carry out targeted detection according to different clinical features for NSCLC.

Analysis of multigene detection in patients with advanced lung adenocarcinoma using cytological specimens

ObjectiveTo investigate the mutation status and clinical characteristics of multigene detection in advanced lung adenocarcinoma using cytological specimens. Materials and Methods137 advanced lung adenocarcinoma patients with 10 driver genes detection in the Fourth Hospital Hebei Medical University from January 2019 to November 2019 was analysized. 137 cytological specimens including fine-needle aspiration specimens and maligant serous cavity effusion (pleural effusion, peritoneal and pericardial effusion). Ten driver mutations of EGFR, ALK, ROS1, BRAF, KRAS, NRAS, HER2, RET, PIK3CA and MET were detected by the amplification refractory mutation system (ARMS). Meanwhile, 90 of 137 patients were detected with biopsies for parallel gene detection. Results78.10 % (107/137) of patients with advanced lung adenocarcinoma harbored at least one of 10 driver mutations. The three main mutations were EGFR (69.16 %, 74/137), ALK (6.57 %, 9/137)and ROS1 (3.65 %, 5/137) mutations. Besides, we found 6 cases including two concomitant mutations: EGFR Exon19 del/HER2 (1/137), EGFR Exon21 L858R/PIK3CA (2/137), EGFR Exon21 L858R/RET (1/137), and ALK/KRAS (2/137). Among 137 patients, women aged 64 or older were more likely to have the mutations (P < 0.05). Female patients (P = 0.003) older or equal to 64 years (P = 0.015) with non-smoking habbit (P = 0.027) were more detected with EGFR mutations, while ALK was more detectable in patients yonger than 64 years. Parallel analysis showed that rates of single EGFR, ALK, ROS1, RET, KRAS, NRAS, HER2, MET mutations and concomitant different mutations were not significantly different between cytological specimens and matched histological specimens. ConclusionsIn the study, cytological specimens and biopsy samples have a very high coincidence rate of gene detection. EGFR, ALK and ROS1 mutations were the main driver mutations in patients with advanced lung adenocarcinoma.We speculate that EGFR and ALK are more prone to concomitant mutations respectively and the treatment of advanced lung adenocarcinoma patients with concomitant mutations deserves further study. The rate of KRAS, NRAS, BRAF, PIK3CA, RET and MET exon14 skipping mutation were low but may had a significant impact on the targeted therapy of patients with advanced lung adenocarcinoma.

The prevalence of targetable genomic alterations is substantially high in rare tumors.

e13539 Background: Comprehensive Genomic Profiling may be informative for novel treatment strategies and to improve outcome for patients with rare solid tumors. This study aims to discover opportunities for use of targeted therapies currently in routine practice in patients with rare tumors. Methods: Solid tumors with an incidence lower than 2.5/100,000 per year was defined as rare tumors in China after comprehensive analysis based on epidemiology data and current availability of standardized treatment. Genomic data of rare tumors from the public database cBioPortal was compared with that of Chinese population for targetable genomic alterations (TGAs). TGAs was defined as mutations of ALK, ATM, BRAF, BRCA1, BRCA2, CDKN2A, EGFR, ERBB2, FGFR1,2,3, KIT, MET, NF1, NTRK1,2,3, PIK3CA, PTEN, RET, and ROS1 with level 1 to 4 of evidence according to OncoKB knowledge database. Results: Genomic data of 4901 patients covering 63 subtypes of rare tumor from cBioportal was obtained as the western cohort. Data of next generation sequencing (NGS) of 1312 patients from across China covering 67 subtypes was summarized as the Chinese cohort. Forty-one subtypes were overlapped between the two cohorts. The accumulative prevalence of TGAs was 20.40% (1000/4901) in cBioportal cohort, and 53.43% (701/1312) in Chinese cohort (p &lt; 0.001). Among those 41 overlapping subtypes, it was still significantly higher in Chinese cohort compared with cBioportal cohort (54.1%% vs. 26.1%, p &lt; 0.001). Generally, targetable mutations in BRAF, BRCA2, CDKN2A, EGFR, ERBB2, KIT, MET, NF1, ROS1 were ≥3 times more frequent in Chinese cohort compared with that of cBioportal cohort. Cancer of unknown primary tumor type, gastrointestinal stromal tumor, gallbladder cancer, intrahepatic cholangiocarcinoma, and sarcomatoid carcinoma of the lung were the top 5 tumor types with highest TGAs. Conclusions: The incidence of TGAs in rare tumors was substantially high worldwide and was even higher in Chinese rare tumor population. Comprehensive genomic profiling may offer novel treatment paradigms to address the limited options for patients with rare tumors.

The next-generation RET inhibitor TPX-0046 is active in drug-resistant and naïve RET-driven cancer models.

3616 Background: RET fusions/mutations drive oncogenesis in lung and thyroid cancers, and several other malignancies. Selective RET inhibitors (selpercatinib/pralsetinib) are active in patients with these cancers; unfortunately, resistance often occurs. On-target resistance includes the acquisition of solvent front mutations (SFMs i.e. RET G810 substitutions). TPX-0046 is a structurally differentiated RET inhibitor that is potent against a range of RET fusions and mutations including SFMs. Methods: The rationally-designed, compact, macrocyclic RET/SRC inhibitor TPX-0046 was characterized in RET-driven in vitro and in vivo tumor models. Results: In enzymatic assays, TPX-0046 showed low nanomolar potency against wild-type RET and 18 RET mutations/fusions. It was potent against SRC and spared VEGFR2/KDR. TPX-0046 inhibited RET phosphorylation (IC50 &lt; 10 nM) in tumor cell lines (LC2/ad, CCDC6-RET; TT, RET C634W) and Ba/F3 engineered RET models (WT, G810R). In cell proliferation assays, TPX-0046 inhibited KIF5B-RET Ba/F3, LC2/ad, and TT cells with IC50 values ~1 nM. Ba/F3 RET engineered cells with SFMs (e.g. G810C/R/S) were potently inhibited by TPX-0046 (mean proliferation IC50 1–17 nM). TPX-0046 demonstrated marked in vivo anti-tumor efficacy in RET-driven cell-derived and patient-derived xenograft tumor models. In a Ba/F3 KIF5B-RET xenograft model, a single dose of 5 mg/kg TPX-0046 inhibited &gt; 80% of RET phosphorylation (corresponding mean free plasma concentration: 51 nM). At 5 mg/kg BID, tumor regression was observed in RET-dependent xenograft models, including those that harbor RET SFMs: TT, CTG-0838 PDX (NSCLC, KIF5B-RET), CR1520 PDX (CRC, NCOA4-RET), Ba/F3 KIF5B-RET, and Ba/F3 KIF5B-RET G810R. Conclusions: TPX-0046 is a unique next-generation RET inhibitor that possesses potent in vitro and in vivo activity against a diverse range of RET alterations, including SFM-mediated resistance. A phase 1/2 trial for RET inhibitor-resistant and naïve RET-driven cancers is on-going (NCT04161391).

RAS-mutated sporadic medullary thyroid cancer: A single-center experience.

6584 Background: Activating RAS mutations are recognized as important drivers in sporadic medullary thyroid cancer (sMTC), with a reported prevalence between 0-43%. However, few studies have looked at correlations between RAS-mutated sMTC and clinicopathologic features. Methods: Patients with sMTC diagnosed between 1992 – 2019 with NGS testing for RET and RAS mutations seen at a tertiary cancer center were retrospectively evaluated. The objective was to analyze demographic and clinical features among patients with RAS-mutated sMTC and to evaluate associations between these features and overall survival (OS). Analyses were performed to correlate patient demographics and pathologic staging with treatment characteristics, disease course, and OS. Results: We identified 42 patients (50% female) with RAS-mutated sMTC out of 218 pts with sMTC. Median age at diagnosis was 50 years (range 24-78 years). 26 (62%) patients had stage IV disease at time of diagnosis. 28 (67%) of patients had HRAS mutations and 14 (33%) had KRAS mutations. HRAS Q61R was the most common HRAS mutation type (n = 19, 45%). Median follow-up time was 64 months (range 23-274 months) during which 11 (26%) patients died. The median OS was 16.2 years, with 5- and 10- year OS of 88% and 73% respectively. Of the 20 (48%) patients who received systemic therapy, 79% had stage IV disease and tended to be older (median age 54). Median time from diagnosis to initiation of systemic therapy was 33 months. Factors associated with worse OS included distant metastases at diagnosis, shorter time interval between diagnosis and treatment, and Ctn/CEA doubling times &lt; 6 months. HRAS Q61R mutations were associated with a better prognosis, with 100% 10-year OS compared with 10-year OS of 39% and 51% (p = 0.02) for other HRAS and KRAS mutations respectively. Conclusions: At a tertiary cancer center, patients with RAS-mutated sMTC had a 10-year OS rate of 73%, with significantly worse OS in patients with HRAS/KRAS mutations other than HRAS Q61R. In comparison, prior studies have reported 10-year OS rates between ~71-90% in sMTC and 10-year OS rates as low as 56% for more aggressive RET M918T sMTC mutations. The findings here are consistent with other studies that have suggested patients with RAS-mutated sMTC are at intermediate risk for aggressive disease, though there are limited data on OS rates in RAS or RAS-/RET- sMTC. Future research comparing outcomes between various RAS mutations and in comparison to RET+ and RAS-/RET- patients is needed, especially as systemic therapy use in RAS-mutated sMTC evolves.

Genomic comparisons between different radiological features in ground glass nodules under 20 mm in diameter.

e13664 Background: Radiological features still matters in the management of ground glass nodules (GGNs). The 20 mm in maximum diameter and consolidation tumor ratio (CTR) under 0.5 are pivotal indexes from the lobectomy to segmentectomy decision. However, the feasibility of limited resection remains controversial. Understanding the relationship between genomic characteristics and radiological features of GGNs will provide critical insights to theoretical basis of surgical method decision and expand a novel perspective to risk-stratify patients. Methods: In total, 297 surgically resected GGNs (≤ 20 mm in maximum diameter) were consecutively collected in the study. The summarized radiological features are shown (Table). In order to obtain their comprehensive genomic profiling, these tumor samples were performed using customized panels of 1021 genes. Fisher's exact test, Mann Whitney test and Kruskal-Wallis test were used for statistical analysis. Results: Higher TMB was found in subgroups with the maximum diameter &gt; 10 mm, the volume &gt; 0.40 mL, the CT value &gt; -500 HU, and the mass &gt; 200 mg ( p &lt; 0.05). However, TMB was not associated with the increase of CTR. These data suggested that enlarged nodules occurred with increased mutation events. EGFR, RET, TP53 and RBM10 mutations were significantly enriched in groups with maximum diameter &gt; 10 mm, volume &gt; 0.40 mL, and mass &gt; 0.200 g ( p &lt; 0.05), and significant enrichment in p53-pathway and Myc-pathway were also found ( q &lt; 0.05). ERBB2 and BRAF mutations were significantly enriched in the subgroups with maximum diameter ≤ 10 mm, volume ≤ 0.40 mL, or mass ≤ 0.200 g ( p &lt; 0.05). As compared to the cohort of CTR ≤ 0.5 in all nodules, mutation frequencies of EGFR, RBM10 were similar, those of RET, ALK and TP53 were relatively higher ( p &lt; 0.05), and that of ERBB2 was lower ( p = 1.7×10−5) in the cohort of CTR &gt; 0.5. Conclusions: Our study provides the comprehensive description of the mutational landscape and radio-genomic features of GGNs under 20 mm in diameter. [Table: see text]

Foundation One Genomic Interrogation of Thyroid Cancers in Patients With Metastatic Disease Requiring Systemic Therapy.

Clinical applications of genomic assessment of thyroid cancers are rapidly evolving. We studied tumor samples from patients with imminently threatening and rare thyroid cancers to identify genomic alterations that might correlate with outcomes and/or be productively therapeutically targetable. Progressive and metastatic, and/or rare, thyroid cancers were studied, 2012 to 2016, at Mayo Clinic sites. The intervention was Foundation One tumor interrogation. Main outcome measures included genomic alterations, patient characteristics, and overall survival. Samples from 55 patients were evaluated: 20 anaplastic thyroid cancers (ATCs) (36%), 25 radioactive iodine-refractory differentiated thyroid cancers (DTCs)/poorly differentiated thyroid cancers (PDTCs) (45%; 14 papillary thyroid cancer [PTCs], 6 PDTCs, 5 Hürthle cell cancers), 8 medullary thyroid cancers (MTCs) (15%), and 2 others (a spindle epithelial tumor with thymus-like differentiation, and a primary thyroid sarcoma). Overall, 72% of DTCs, 79% of ATCs, and 75% of MTCs were deemed to have potentially productively targetable alterations. The most commonly encountered mutation was of TERT promoter (56% of DTCs, 68% of ATCs)-but this is not presently targetable. Targetable BRAFV600E mutations were found in 40% of DTCs/PDTCs (83% of PTCs) and 32% of ATCs; of MTCs, 75% had targetable RET mutations, and 25% HRAS mutations. Of patient tumors with nonmutated BRAFV600E, 53% of DTC/PDTCs and 69% of ATCs had other potentially productively targetable mutations. Genomic alterations in our series of poor prognosis metastatic DTC/PDTCs also closely resembled those seen in ATC. Whereas genomic interrogation of favorable prognosis thyroid cancer seems ill advised, potentially productively targetable mutations were demonstrated in the majority of tumors from patients with metastatic thyroid cancers requiring systemic therapy, suggesting a rationale for the selective application of this technology.

Chinese siblings with hereditary medullary thyroid carcinoma caused by RET mutation: implications for RET oncogene detection

BackgroundHereditary medullary thyroid carcinoma (MTC) is mainly caused by germline mutations in the RET proto-oncogene, which accounts for 20–30% of all MTC according to foreign studies. However, no English literatures have reported Chinese hereditary MTC. Here, we reported two Chinese brothers with MTC that caused by germline RET mutation.Case presentationThe younger brother was diagnosed with MTC at 29 years ago and suffered recurrence more than 10 years. For elder brother, the diagnosis of MTC was made by postoperative pathological examination at age 61. Both patients received total thyroidectomy and lymph node dissection. Since they had a significant family history for MTC, genetic detection was performed and identified a germline mutation in RET exon 10 (p.C620Y). This mutation was also detected in their offspring, indicating a moderate risk of MTC.ConclusionsThis is the first report presenting a Chinese family with hereditary MTC caused by the RET p.C620Y variant. This case series emphasize the importance of genetic detection of RET proto-oncogene for MTC patients, and bring out managements for individuals after detection of RET mutations.

MON-509 RET Mutations in the MEN1 Syndrome: Is It an Innocent Bystander?

IntroductionMENIN and RET mutations in MEN1 families, are rare, and, when they co-exist either mutation may predominate the clinical picture.We report a family, with both mutations, and, suspect that the RET mutation may not be an innocent bystander.Clinical CasesGM (36M): 2009: Presented with skin lesions and a lactotroph adenoma causing chiasmal compression. Treatment: Hypophysectomy and Cabergoline. This resulted in restoration of sexual function and fertility.2013: Developed hyperparathyroidism [Calcium 10.6mg% (8.5-10.5); PTH 610pg/ml (10-65); MIBG Scan: parathyroid adenomas]. Treatment: Subtotal parathyroidectomy with allotransplant.2015: Developed Zollinger-Ellison Syndrome [multiple gastric ulcers; S Gastrin: 516pg/ml; (0-180)]. Treatment: Pantoprazole.MRI Abdomen: Calcific atrophic pancreas and bilateral non-functioning adrenal adenomas.HM (32M): 2008: Skin lesions and Lactotroph adenoma. Treatment with Cabergoline resulted in restoration of sexual function and a reduction in breast and tumour size.2013: Hyperparathyroidism [Calcium 10.9mg%; PTH: 166pg/ml; Calcium excretion: 1160mg/24hrs (100-250); BMD: Osteopenia. MIBG 123 Scan: Avid uptake in Right Inferior parathyroid gland]. He underwent a subtotal parathyroidectomy with allotransplant.2015: Recurrent Hyperparathyroidism (Calcium 10.7mg%; PTH: 116pg/ml; MIBG 123 scan: Hyperfunction of the transplanted gland). Stable on treatment with Cinacalcet.Their mother, AM (42F): 1980: Detected to have a lactotroph adenoma when investigated for primary infertility and galactorrhoea. She was treated with Bromocriptine and delivered the boys in 1980 and 1984 respectively. She had recurrent renal calculi and hydronephrosis (? hyperparathyroidism). She succumbed to renal failure following surgery for a benign pancreatic cystadenoma in 1990.DiscussionWhole exome sequencing of GM and HM showed pathogenic mutations of both, MENIN and RET gene. The precise mutation was a stop gain mutation at exon 3 MENIN.C511T:p.Q171X . They (GM/HM) also harboured a mutation in the RET gene at exon 14 c. G2492T: p.G831V; g. chr10. This may be the first family in which the rare combination of these two mutations has been reported.The genomics and the clinical presentation suggest that the MENIN mutation predominates in the family, but the presence of bilateral adrenal adenomas in GM are significant on account of RET mutation. The latter may be a harbinger of serious disease in the future. The situation is further compounded by the recurrence of hyperparathyroidism in the allograft of HM. This may be caused due to chance or an unknown genetic/ epigenetic phenomenon in the two MEN mutated genes and RNA sequencing of the tumour tissue may explain the genetic phenomenon. The latter two events suggest that the RET mutations in MEN1 may not be an innocent bystander.

MON-906 MULTIPLE ENDOCRINE NEOPLASIA TYPE 2A: Familiar Case Report

Introduction: Multiple endocrine neoplasia type 2A (MEN 2A) is a autosomal dominant transmission inherited syndrome which oncogenesis is based on germline mutations with RET proto-oncogene function gain. Patients have medullary thyroid carcinoma (CMT) and some develop unilateral or bilateral pheochromocytoma and/or primary hyperparathyroidism, its frequency depends on the inherited RET mutation. We present a case of a mother and daughter with marfanoid habitus and MEN 2A syndrome confirmed by genetic analysis that identified mutation in the RET gene, codon 634.Clinical cases: 35-year-old woman with weight loss, sweating, nausea, hypertensive peaks, syncope episodes and marfanoid habitus, with plasma metanephrines 9.1nmol/L (RV<0.5), bilateral adrenal tumors on MRI (4.7x4.5x3.3 cm left adrenal and 7.4x7.3x6.3 cm) and MIBG scintigraphy high uptake bilateral, with diagnosis of bilateral pheochromocytoma. She also had calcitonin 49.40pg/mL (RV<6.4), calcium 11.9mg/dL (RV 8.6-10.2), PTH 372.7pg/mL (RV15-65) and cervical ultrasound (USG) with solid and hypoechogenic thyroid nodule, diagnosed with CMT and primary hyperparathyroidism with 6 possible parathyroid glands by SPECT CT scintigraphy. Genetic panel by NGS identify germline mutation in RET códon 634 - minsense mutation: c.1900T>C. The patient denied prior family history. In the familiar screening, her 18-year-old daughter has a marfanoid habitus, serum calcitonin 48.8pg /mL (RV<9.8), CEA 3.8ng/mL(RV<3.0), cervical USG shows a thyroid nodule of 0.7x0.5x0.5cm, solid, hypoechoic, with microcalcifications and a central compartiment lymph node, whose puncture calcitonin > 2000pg/mL and 118pg/mL, respectively. She features plasma metanephrines 0.5mmol/L (RV<0.5), normal plasma normetanephrines, MIBG scintigraphy and adrenal MRI without alterations and absence of primary hyperparathyroidism. She has the same mutation as her mother.Conclusion: Although rare, it is essential to know the clinical and laboratory changes in MEN 2A in order to enable early diagnosis and treatment. Also, investigate every first-degree relative is important so complications and mortality of this syndrome can be reduced.

SUN-LB75 The Anti-Tumor Activity of the Selective Ret Inhibitor Selpercatinib (LOXO-292) in Medullary Thyroid Cancer Is Independent of the Specific RET Mutation

The RET receptor tyrosine kinase proto-oncogene is activated by somatic or germline mutations in a majority of medullary thyroid cancers (MTC). However, treatment of MTC has been challenging due to the lack of effective and tolerable RET-specific therapy, thus testing tumors for the presence of somatic RET mutation has not been warranted. In a first-in-human, phase 1/2 clinical trial (LIBRETTO-001, NCT03157128), selpercatinib (LOXO-292), an investigational, highly selective, potent small molecule RET kinase inhibitor, demonstrated significant and durable anti-tumor activity in patients with advanced RET-mutant MTC or with diverse RET fusion-positive cancers (1). Among the primary analysis set of patients with RET-mutant MTC previously treated with cabozantinib and/or vandetanib (N=55), the investigator-assessed objective response rate (ORR) per RECIST 1.1 was 56% (95% CI 42.3-69.7, n=31/55). Duration of response was not reached with a 10.6-months median follow-up (data cutoff date 17-Jun-2019). Here, we evaluated investigator-assessed ORR per RECIST 1.1 and clinical benefit rate (CBR) in this previously treated patient population by RET alteration and by germline or somatic testing used for enrollment. The ORR remained consistent across subgroups with RET M918T (49%, 95% CI 30.8-66.5, n=16/33), V804M/L gatekeeper mutations (60%, 95% CI 14.7-94.7, n=3/5), extracellular cysteine mutations (43%, 95% CI 9.9-81.6, n=3/7), other mutations (90%, 95% CI 55.5-99.7, n=9/10), and germline (50%, 95% CI 6.8-93.2, n=2/4) or somatic (57%, 95% CI 42.2-70.7, n=29/51) testing. The CBR, defined as the proportion of patients with best overall response of confirmed complete response, confirmed or unconfirmed partial response, or stable disease lasting 16 weeks or more, in this patient set was 87% (95% CI 75.5-94.7, n=48/55). The CBR remained consistent across subgroups with RET M918T (88%, 95% CI 71.8-96.6, n=29/33), V804M/L gatekeeper mutations (80%, 95% CI 28.4-99.5, n=4/5), extracellular cysteine mutations (71%, 95% CI 29.0-96.3, n=5/7), other mutations (100%, 95% CI 69.2-100.0, n=10/10), and germline (75%, 95% CI 19.4-99.4, n=3/4) or somatic (88%, 95% CI 76.1-95.6, n=45/51) testing. The primary technologies used to identify RET alterations were tumor next-generation sequencing (n=43) and polymerase chain reaction (n=9). As previously reported, selpercatinib was well tolerated with an acceptable safety profile (1). These results indicate broad anti-tumor activity for selpercatinib in patients with RET-mutant MTC irrespective of the specific RET mutation, and support implementation of RET mutation testing for patients with advanced MTC, including somatic testing, to identify patients who may benefit from selpercatinib. Reference: (1) Wirth et al., Ann Oncol. 2019 Oct; 30(supplement 5): v933.

MON-196 A Single-Center Experience of Patients with Metastatic Pheochromocytoma/Paraganglioma Treated with 177Lu-DOTATATE

The prevalence of metastatic pheochromocytoma/paraganglioma (PPGL) is reported to be 3% to 36% of all the cases. The five-year overall survival rate of such patients ranges from 40 to 77%. The management of metastatic PPGL is challenging taking into account the fact that the optimal strategies for clinical care beyond surgical resection are not guided yet. Peptide receptor radionuclide therapy (PRRT) using somatostatin analogues is effective in other neuroendocrine tumours, can be indicated in patients with positive scans for the respective radiopharmaceuticals.We report preliminary data of the prospective study aimed to assess the safety and efficacy outcomes of 177Lu-DOTATATE for 6 patients with histologically confirmed PPGLs with metastatic progression after the complete PPGL surgery. The mean age of our cohort was 53 years (range 14–73); an equal number of male and female patients was included. Two of them had germline mutations in RET and SDHB genes, respectively. Radiological response utilized RECIST 1.1 criteria; toxicity was graded according to common terminology criteria for adverse events version 4. PPRT scheme varied between three and four cycles. Partial response (PR) was achieved in one and stable disease (SD) in four 4 patients. One patient had treatment refractory with disease progression and dramatic increase of chromogranin A concentration (+268%). Biochemical response (>50% decrease) of chromogranin A was found in 1/6 patients and of catecholamines in 2/6 patients. No hematological or kidney toxicity grade 3–4 was registered.Median overall survival and median progression-free survival rate will be reported after the end of the study.To date, about 250 PPGL patients have been treated with PRRT. PRRT using 177Lu-DOTA-SSAs has shown promise for treatment of PPGLs with improvement of clinical symptoms and/or disease control in the setting of retrospective small case reports or case series. However, more well-designed prospective studies are required to confirm these findings.

MON-218 Clinical and Genetic Aspects of Pediatric Pheochromocytomas and Paragangliomas

Pheochromocytomas and paragangliomas (PPGLs) are neuroendocrine tumors derived from chromaffin cells. At least 30% of PPGL patients have hereditary predisposition. PPGLs in children are more often hereditary, multiple and extra-adrenal. To date, more than 14 tumor-susceptibility genes have been reported: Cluster 1 or hypoxic (VHL, SDHB, SDHD, SDHC, SDHA, SDHAF2, FH, ENGL1 and HIF2A) and cluster 2 (RET, NF1, TMEM127 and MAX). The aim of this study was to evaluate clinical and molecular aspects of a Brazilian cohort of pediatric patients with PPGLs. Out of 262 patients with PPGLs, 26 (9 %) were diagnosed before 19 yrs of age (16 males and 10 females), with a median age of 14.5 yrs (range, 4 to 18). Genetic investigation was performed in 19 patients: 14 by automated Sanger sequencing (VHL, SDHB, SDHD and RET genes) and 5 by a custom next-generation sequencing (NGS) panel including all genes previously associated with germline mutations in PPGLs. Median tumor size was 5.5 cm (1.7 to 16). Pheochromocytomas (PHEOs), paragangliomas (PGLs) or both were diagnosed in 46%, 31% and 23% of the patients, respectively. Bilateral PHEOs were diagnosed in 61% of the cases, most of them asynchronous (75%). Genetic diagnosis was confirmed in 14 out of 19 (74%) patients and all variants were found in heterozygous state: 8 VHL missense mutations from 6 kindreds (p.R167W in 2 kindreds, p.R167Q in one and p.G114S in 3); 3 SDHB mutations (p.C98Y, c.201-2A>G and p.L180L); 2 SDHD mutations (p.Y144_H145del and p.Q121*); and one RET mutation (p.C634R). All 8 VHL patients had bilateral PHEOs and 3 of them had also abdominal PGLs. All patients with SDHB mutations had abdominal PGLs. Two patients with SDHD mutation had head and neck paraganglioma (one of them had unilateral PHEO). Genetic investigation by NGS Panel was negative in all 5 cases: 2 malignant PPGLs (one PHEO and one PGL) and 3 PHEOs. Four out of 26 (15%) pediatric PPGLs were malignant: 2 with SDHB mutation and 2 with negative screening (one PHEO and one PGL). In conclusion, the majority of pediatric PPGLs (74%) were hereditary and almost exclusively caused by mutations in hypoxic genes. VHL (PHEOs) and SDHB (only PGLs) were the most frequent affected genes in this cohort of pediatric PPGLs. Support: CAPES grant to Petenuci J.