Recurrent Middle Eastern Differentiated Thyroid Carcinoma Has Worse Outcomes Than Persistent Disease

Background: Despite the excellent prognosis of differentiated thyroid carcinoma (DTC), recurrent and persistent disease remain major challenges. Emerging studies to differentiate between recurrent and persistent disease are controversial, with studies from the Middle East lacking. Methods: We retrospectively analyzed 1691 patients who underwent surgery ± I131 treatment for DTC, with a median age of 38.7 years and median follow-up of 95.3 months. Results: We found a similar prevalence rate for persistent and recurrent disease (17.7% vs. 17.9%) in Middle Eastern DTC patients. Relative to patients with persistent disease, patients with recurrent disease were significantly older (median age: 36.1 vs. 45.8 years; p < 0.0001) and were more likely to have ATA high-risk tumors (61.5% vs. 75.2%; p = 0.0003). On multivariate logistic regression analysis, both T and N status were independent predictors for recurrent as well as structural persistent disease. However, older age, bilaterality and extrathyroidal extension were independent predictors of recurrent disease alone. In addition, patients with recurrent disease had significantly worse cancer-specific survival (p < 0.0001), which remained significant in multivariate analysis. Conclusions: Although persistent and recurrent disease in Middle Eastern DTC have similar frequencies, recurrent disease has worse outcomes compared to persistent disease. Hence, differentiating recurrence from persistence has great potential clinical relevance for therapeutic and follow-up approaches, contributing to improving the outcomes of DTC patients of Middle Eastern ethnicity.

PLK1 and FoxM1 expressions positively correlate in papillary thyroid carcinoma and their combined inhibition results in synergistic anti-tumor effects

Polo-like kinase 1 (PLK1; also known as serine/threonine-protein kinase PLK1) serves as a central player in cell proliferation, exerting critical regulatory roles in mitotic processes and cell survival. We conducted an analysis of PLK1 protein expression in a large cohort of samples from papillary thyroid carcinoma (PTC) patients and examined its functional significance in PTC cell lines, both in vitro and in vivo. PLK1 overexpression was noted in 54.2% of all PTC and was significantly associated with aggressive clinicopathological parameters; it was also found to be an independent prognostic marker for shorter recurrence-free survival. Given the significant association between PLK1 and forkhead box protein M1 (FoxM1), and their concomitant overexpression in a large proportion of PTC samples, we explored their correlation and their combined inhibitions in PTC in vitro and in vivo. Inhibition of PLK1 expression indeed suppressed cell proliferation, leading to cell cycle arrest and apoptosis in PTC cell lines. Significantly, the downregulation of PLK1 reduced the self-renewal capability of spheroids formed from PTC cells. Immunoprecipitation analysis shows that PLK1 binds to FoxM1 and vice versa in vitro. Mechanistically, PLK1 knockdown suppresses FoxM1 expression, whereas inhibition of FoxM1 does not affect PLK1 expression, which suggests that PLK1 acts through the FoxM1 pathway. The combined treatment of a PLK1 inhibitor (volasertib) and a FoxM1 inhibitor (thiostrepton) demonstrated a synergistic effect in reducing PTC cell growth in vitro and delaying tumor growth in vivo. This study highlights the important role of PLK1 in PTC tumorigenesis and prognosis. It also highlights the synergistic therapeutic potential of dual-targeting PLK1 and FoxM1 in PTC, unveiling a potential innovative therapeutic strategy for managing aggressive forms of PTC.

PLK1 and PARP positively correlate in Middle Eastern breast cancer and their combined inhibition overcomes PARP inhibitor resistance in triple negative breast cancer

Background

Despite advancements in treatment approaches, patients diagnosed with aggressive breast cancer (BC) subtypes typically face an unfavorable prognosis. Globally, these cancers continue to pose a significant threat to women's health, leading to substantial morbidity and mortality. Consequently, there has been a significant struggle to identify viable molecular targets for therapeutic intervention in these patients. Polo-like Kinase-1 (PLK1) represents one of these molecular targets currently undergoing rigorous scrutiny for the treatment of such tumors. Yet, its role in the pathogenesis of BC in Middle Eastern ethnicity remains unexplored.

Methods

We investigated the expression of PLK1 protein in a cohort of more than 1500 Middle Eastern ethnicity BC cases by immunohistochemistry. Association with clinicopathological parameters and prognosis were performed. In vitro studies were conducted using the PLK1 inhibitor volasertib and the PARP inhibitor olaparib, either alone or in combination, in PTC cell lines.

Results

Overexpression of PLK1 was detected in 27.4% of all BC cases, and this was notably correlated with aggressive clinicopathological markers. PLK1 was enriched in the triple-negative breast cancer (TNBC) subtype and exhibited poor overall survival (p = 0.0347). Notably, there was a positive correlation between PLK1 and PARP overexpression, with co-expression of PLK1 and PARP observed in 15.7% of cases and was associated with significantly poorer overall survival (OS) compared to the overexpression of either protein alone (p = 0.0050). In vitro, we studied the effect of PLK1 and PARP inhibitors either single or combined treatments in two BRCA mutated, and one BRCA proficient TNBC cell lines. We showed that combined inhibition significantly reduced cell survival and persuaded apoptosis in TNBC cell lines. Moreover, our findings indicate that inhibition of PLK1 can reinstate sensitivity in PARP inhibitor (PARPi) resistant TNBC cell lines.

Conclusion

Our results shed light on the role of PLK1 in the pathogenesis and prognosis of Middle Eastern BC and support the potential clinical development of combined inhibition of PLK1 and PARP, a strategy that could potentially broaden the use of PLK1 and PARP inhibitors beyond BC cases lacking BRCA.

Identification and characterization of ATM founder mutation in BRCA-negative breast cancer patients of Arab ethnicity

Breast cancer (BC) is the most prevalent malignancy among women worldwide with germline pathogenic variants/likely pathogenic variants (PVs/LPVs) in BRCA1/2 accounting for a large portion of hereditary cases. Recently, heterozygous PVs/LPVs in the ATM serine/threonine kinase or Ataxia-telangiectasia mutated gene (ATM) has been identified as a moderate susceptibility factor for BC in diverse ethnicities. However, the prevalence of ATM PVs/LPVs in BC susceptibility in Arab populations remains largely unexplored. This study investigated the prevalence of ATM PVs/LPVs among BC patients from Saudi Arabia, employing capture-sequencing technology for ATM PVs/LPVs screening in a cohort of 715 unselected BC patients without BRCA1/2 PVs/LPVs. In addition, founder mutation analysis was conducted using the PHASE program. In our entire cohort, four unique PVs/LPVs in the ATM gene were identified in six cases (0.8%). Notably, one recurrent LPV, c.6115G > A:p.Glu2039Lys was identified in three cases, for which haplotype analysis confirmed as a novel putative founder mutation traced back to 13 generations on average. This founder mutation accounted for half of all identified mutant cases and 0.4% of total screened cases. This study further reveals a significant correlation between the presence of ATM mutation and family history of BC (p = 0.0127). These findings underscore an approximate 0.8% prevalence of ATM germline PVs/LPVs in Arab BC patients without BRCA1/2 PVs/LPVs and suggest a founder effect of specific recurrent ATM mutation. These insights can help in the design of a genetic testing strategy tailored to the local population in Saudi Arabia, thereby, enabling more accurate clinical management and risk prediction.

Loss of CDH16 expression is a strong independent predictor for lymph node metastasis in Middle Eastern papillary thyroid cancer

Papillary Thyroid Cancer (PTC) is the most common type of thyroid cancer. The membrane-associated glycoprotein cadherin-16 (CDH16) plays a significant role in the embryonal development of thyroid follicles and cell adhesion. Previous studies have indicated a substantial downregulation of CDH16 in PTC. However, its role in Middle Eastern PTC has not been elucidated. We analyzed a tissue microarray comprising 1606 PTC and 240 normal thyroid tissues using immunohistochemistry to assess CDH16 expression and determine its clinico-pathological associations. We also conducted BRAF and TERT mutations analyses through Sanger sequencing. Disease-free survival (DFS) was assessed using Kaplan-Meier curves. CDH16 immunostaining was seen in 100% of normal thyroid tissues but only in 9.4% of PTC tissues (p < 0.0001). The loss of CDH16 expression was associated with aggressive PTC characteristics including bilaterality, multifocality, extrathyroidal extension, tall cell variant, lymph node metastasis (LNM) and distant metastasis. Additionally a correlation between loss of CDH16 expression and BRAF and TERT mutations was identified. Intriguingly, upon conducting multivariate logistic regression analysis, CDH16 was determined to be an independent predictor for LNM (Odds ratio = 2.46; 95% confidence interval = 1.60-3.79; p < 0.0001). Furthermore, CDH16 loss was associated with a shorter DFS (p = 0.0015). However, when we further subdivided CDH16 negative patients based on the co-existence of TERT and/or BRAF mutations, we found that patients with both CDH16 negative expression and TERT mutation exhibited the shortest DFS (p < 0.0001). In conclusion, our results suggest that CDH16 protein expression could serve as a valuable diagnostic tool for PTC. Furthermore, these findings demonstrate that the loss of CDH16 expression is an independent predictor of LNM and may contribute to the aggressiveness of PTC. Therefore, downregulation of CDH16 in PTC might be a potential target for designing novel therapeutic strategies to treat PTC.

Predictive risk factors for distant metastasis in pediatric differentiated thyroid cancer from Saudi Arabia

Background

Despite their excellent prognosis, children and young adults (CAYA) with differentiated thyroid cancer (DTC) tend to have more frequent occurrence of distant metastasis (DM) compared to adult DTC. Data about DM in CAYA from Middle Eastern ethnicity is limited.

Methods

Medical records of 170 patients with DTC ≤18 years were retrospectively reviewed. Clinico-pathological factors associated with lung metastasis in CAYA, their clinical presentation and outcome were analyzed. Rick factors related to distant metastasis-free survival (DMFS) for the whole cohort were evaluated.

Results

DM was observed in 27 patients and all were lung metastasis. Lung metastasis was significantly associated with younger age (≤15 years), extrathyroidal extension (ETE), multifocal tumors, bilaterality, presence of lymph node (LN) disease and high post-operative stimulated thyroglobulin (sTg). Highest negative predictive values were seen with low post-operative sTg (97.9%), absence of LN disease (93.8%), absence of ETE (92.2%) and age older than 15 years (92.9%). Post-therapy whole body scan (WBS) identified most of the lung metastasis (21 of 27; 77.8%). Upon evaluating patients response according to ATA guidelines, excellent response was seen in only one patient, while biochemical persistence and structural persistence were seen in 11.1% (3/27) and 77.8% (21/27), respectively. Elevated post-operative sTg (>10ng/ml) was the only risk factor found to be significantly associated with both biochemical persistence (with or without structural persistence (p = 0.0143)) and structural persistence (p = 0.0433). Cox regression analysis identified age and post-operative sTg as independent risk factors related to DMFS. Based on these two risk factors for DMFS, patients were divided into 3 groups: low risk (no risk factors), intermediate risk (1 risk factor) and high risk (both risk factors). 20-year DMFS rates in the low-, intermediate- and high-risk groups were 100.0%, 81.3% and 23.7% respectively (p < 0.0001).

Conclusion

Higher suspicion for metastatic pediatric DTC should be considered in patients who are young, have LN disease, extrathyroidal extension and elevated post-operative sTg. Persistent disease, despite therapy, is very common and it appears to be related to post-operative sTg level. Hence, risk adaptive management is desirable in CAYA with DTC.

Whole Exome-Wide Association Identifies Rare Variants in GALNT9 Associated with Middle Eastern Papillary Thyroid Carcinoma Risk

Papillary thyroid carcinoma (PTC) is the commonest thyroid cancer. The majority of inherited causes of PTC remain elusive. However, understanding the genetic underpinnings and origins remains a challenging endeavor. An exome-wide association study was performed to identify rare germline variants in coding regions associated with PTC risk in the Middle Eastern population. By analyzing exome-sequencing data from 249 PTC patients (cases) and 1395 individuals without any known cancer (controls), GALNT9 emerged as being strongly associated with rare inactivating variants (RIVs) (4/249 cases vs. 1/1395 controls, OR = 22.75, p = 5.09 × 10-5). Furthermore, three genes, TRIM40, ARHGAP23, and SOX4, were enriched for rare damaging variants (RDVs) at the exome-wide threshold (p < 2.5 × 10-6). An additional seven genes (VARS1, ZBED9, PRRC2A, VWA7, TRIM31, TRIM40, and COL8A2) were associated with a Middle Eastern PTC risk based on the sequence kernel association test (SKAT). This study underscores the potential of GALNT9 and other implicated genes in PTC predisposition, illuminating the need for large collaborations and innovative approaches to understand the genetic heterogeneity of PTC predisposition.

PALB2 germline mutations in a large cohort of Middle Eastern breast-ovarian cancer patients

The PALB2 gene is a breast cancer (BC) and ovarian cancer (OC) predisposition gene involved in the homologous recombination repair pathway. However, the prevalence and clinicopathological association of PALB2 pathogenic/likely pathogenic (PV/LPV) variants in Middle East is still not fully explored. Total 918 BC/OC patients from Saudi Arabia were selected for PALB2 mutations screening using capture sequencing technology. Five heterozygous PVs or LPVs were identified in six cases, accounting for 0.65% (6/918) of entire cohort. Two cases (33.3%) harbored PVs and four cases (66.7%) carried LPVs. Four PVs/LPVs (80%) were frameshift along with one novel splicing LPV (c.2835-2_2835-1delinsTT). One recurrent LPV (c.3425delT: p.L1142fs) was identified in two cases. All six affected carriers have breast cancer diagnosis with median age of 39.5 years (range 34-49 years). Only two cases (33%) have documented family history of cancer. Breast cancer phenotype was invasive ductal unilateral cancer in all cases with 66.7% of hormone receptor positive and 16% of triple negative tumors. Germline PVs/LPVs in the PALB2 gene were observed in low frequency of 0.65% in Saudi BC and/or OC. Our study confirms one recurrent LPV and one novel LPV in Saudi breast cancer patients.

Overexpression of the pro-protein convertase furin predicts prognosis and promotes papillary thyroid carcinoma progression and metastasis through RAF/MEK signaling

Furin belongs to the pro-protein convertases (PCs) family and its aberrant expression has been documented in various types of cancers; however, its role in thyroid cancer remains unclear. We investigated the expression of furin in a large cohort of Middle Eastern papillary thyroid carcinoma (PTC) patient samples and explored its functional role and mechanism in PTC cell lines in vitro and in vivo. Furin overexpression was observed in 44.6% of all PTC cases and was significantly associated with aggressive clinicopathological parameters and poor outcomes. We show that the knockdown of FURIN suppresses tumor growth, proliferation, migration, invasion, spheroid growth, and progression of epithelial-to-mesenchymal transition (EMT) in B-Raf proto-oncogene, serine/threonine kinase (BRAF) mutant cells, whereas its overexpression in BRAF wild-type PTC cell lines reversed the effect. FURIN knockdown in the BRAF mutant cell line led to reduced tumor growth and increased apoptosis. Mechanistically, FURIN knockdown led to MEK/ERK pathway suppression in BRAF mutant cells, although inhibition of MEK did not affect furin expression, which suggests that furin acts through the MEK/ERK pathway. Furthermore, our study revealed the synergistic antitumor effect of furin depletion and anti-MEK inhibitor treatment. Overall, these results indicate that furin is an important prognostic marker in Middle Eastern PTC and that it plays a crucial role in BRAF-associated MAP/ERK pathway activation and tumorigenesis. Furin inhibition could be a potential therapeutic target for aggressive PTC.

Bilateral multifocality is an independent predictor of patients' outcome in Middle Eastern papillary thyroid carcinoma

Background

Tumor multifocality is frequently seen in Papillary thyroid carcinoma (PTC). However, few studies have analysed the impact of bilateral multifocality in PTC. The incidence of bilateral multifocality, its clinico-pathological associations and prognostic impact in PTC from Middle Eastern ethnicity remains unestablished.

Methods

We retrospectively evaluated 1283 patients who underwent total thyroidectomy for PTC. Bilateral and unilateral multifocality were decided based on the final pathology result. Primary outcome was recurrence free survival (RFS). Risk factors for bilateral multifocality were analyzed by multivariate logistic regression analysis.

Results

Multifocal PTC was found in 54.3% (697/1283) of patients. Among the 697 multifocal PTCs, 210 patients (30.1%) had unilateral multifocal PTC and 487 patients (69.9%) had bilateral multifocality. Bilateral multifocality was significantly associated with older age at diagnosis (p = 0.0263), male gender (p = 0.0201), gross extrathyroidal extension (p = 0.0332), larger primary tumor size (>4cm; p = 0.0002), lateral lymph node metastasis (p = 0.0008), distant metastasis at diagnosis (p = 0.0195) and recurrence (p = 0.0001). Bilateral multifocality was also found to be an independent predictor of RFS (Hazard ratio = 1.60; 95% Confidence Interval = 1.05 - 2.55; p = 0.0300). Multivariate logistic regression analysis demonstrated tumor diameter >4cm to be the only independent risk factors for bilaterality in multifocal PTC (Odds ratio = 1.86; 95% Confidence Interval = 1.13 - 3.07; p = 0.0155).

Conclusions

Incidence of bilateral multifocality is high in Middle Eastern PTC. Tumor diameter >4cm can be considered as a predictive factor for bilateral multifocal PTC. Bilateral multifocality appears to be an important prognostic factor for PTC and an independent predictor of RFS. Therefore, patients with bilateral multifocal PTC may benefit from more frequent follow-up to identify recurrences earlier.

Lynch Syndrome Identification in Saudi Cohort of Endometrial Cancer Patients Screened by Universal Approach

Lynch syndrome (LS) is the most common cause of inherited endometrial cancer (EC). The prevalence and molecular characteristic of LS in Middle Eastern women with EC have been underexplored. To evaluate the frequency of LS in a cohort of EC patients from Saudi Arabia, a total of 436 EC cases were screened utilizing immunohistochemistry (IHC), MLH1 promoter methylation analysis and next-generation sequencing technology. A total of 53 of 436 (12.2%) ECs were classified as DNA mismatch repair-deficient (dMMR). MLH1 promoter hypermethylation was detected in 30 ECs (6.9%). Three ECs (0.7%) were found to be LS harboring germline pathogenic variants (PVs)/likely pathogenic variants (LPVs): two in the MSH2 gene and one in the MSH6 gene. Three ECs (0.7%) were Lynch-like syndrome (LLS) carrying double somatic MSH2 PVs/LPVs. Seven cases were found to have variants of uncertain significance in cancer-related genes other than MMR genes. Our results indicate that LS prevalence is low among Saudi EC patients and LLS is as common as LS in this ethnicity. Our findings could help in better understanding of the prevalence and mutational spectrum of this syndrome in Saudi Arabia, which may help in defining best strategies for LS identification, prevention and genetic counseling for EC patients.

Risk Factors for Cervical Lymph Node Metastasis in Middle Eastern Papillary Thyroid Microcarcinoma

Papillary thyroid microcarcinoma (PTMC) typically has an indolent course and excellent prognosis. Nonetheless, a subset of PTMC carries a risk of lymph node metastasis (LNM) and local recurrence. PTC from the Middle Eastern population is unique with respect to demographic and clinico-pathological characteristics as compared to other ethnicities of the world. The risk factors of LNM in PTMC patients of Middle Eastern ethnicity have not been fully explored. The present study aims to investigate the influencing factors of LNM in Middle Eastern PTMC patients and its predictive impact on patient’s outcome. A total of 226 confirmed PTMC cases were selected in this retrospective study. The correlation between clinico-pathological, as well as molecular, characteristics and LNM was evaluated. Multivariate analysis was performed by logistic regression and Cox proportional hazards models. Among the 226 patients, the rate of LNM was 43.8% (99/226). Bilaterality, multifocality, gross extrathyroidal extension (ETE), and intermediate-to-high American Thyroid Association (ATA) risk tumors were significantly associated with LNM in PTMC. Multivariate logistic regression analysis showed that bilaterality and gross ETE were independent predictive factors for LNM in PTMC. The recurrence-free survival (RFS) was shorter in PTMC with LNM compared to those without LNM (p = 0.0051) and was significant on multivariate analysis. In conclusion, our study showed that bilaterality and gross ETE were independent influencing factors of LNM in Saudi patients with PTMC. LNM was also associated with shorter RFS. The identification of risk factors for LNM in patients of Middle Eastern ethnicity could help the individualization of clinical management for PTMC patients.

Abstract 5776: Predictors of radioactive iodine refractoriness in papillary thyroid carcinomas

Optimized surgery and radioactive iodine (131I, RAI) are the cornerstone of treatment for papillary thyroid carcinoma (PTC). Although standard treatment is curative for most, 5-20% of PTC patients develop RAI refractory disease – the main cause of thyroid cancer-related deaths. Early predictors indicating therapeutic response to RAI therapy in PTC are yet to be elucidated. We performed whole-exome sequencing (at a median depth of 198x) on 158 patient-matched primary PTCs and germline DNA. Clinical data was used to categorize RAI avidity in the PTC cohort. Whereby, 66 RAI refractory and 92 RAI avid tumors were identified. Clinical data and somatic variants were analyzed to compare the clinicopathological presentation, genomic landscape and mutational signatures between RAI refractory and avid PTCs. RAI refractory tumors were significantly associated with distinct aggressive clinicopathological features, including positive surgical margins (65.5% versus 26.7%; p=0.016) and the presence of lymph node metastases at primary diagnosis (62.5% versus 30.1%; p=0.012); higher nonsilent tumor mutation burden (p=0.011); and the enrichment of APOBEC-related single base substitution (SBS) COSMIC mutational signatures 2 (p=0.03) and 13 (p&lt;0.001). APOBEC mutational signatures were not associated with BRAFV600E mutation. Notably, using multivariate logistic regression analysis only the SBS13 (odds ratio 13.01, 95% confidence intervals 1.20-140.94) APOBEC mutational signature was revealed to be an independent predictor of RAI refractoriness in PTC (p=0.035). Furthermore, using Cox proportional hazards SBS13-positive tumors (hazard ratio 3.52, 95% confidence intervals 1.79-6.91) were also significantly associated with poorer progression-free survival (p&lt;0.001), albeit only in univariate analysis. This study highlights distinct clinical and genomic features in RAI refractory PTC, but above all proposes the APOBEC SBS13 mutational signature as an independent predictor of RAI refractoriness in a more aggressive subgroup of PTC. Where detection of RAI refractory disease following standard surgical PTC removal, and more suitable therapeutic interventions may potentially improve patient outcomes.

Citation Format: Tariq Masoodi, Sarah Siraj, Abdul K. Siraj, Saud Azam, Zeeshan Qadri, Sandeep K. Parvathareddy, Khawla S. Al-Kuraya. Predictors of radioactive iodine refractoriness in papillary thyroid carcinomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5776.

Abstract 5177: Lymph node ratio is superior to AJCC N stage for predicting recurrence in papillary thyroid carcinoma

Objective: Recently, lymph node ratio (LNR) has emerged as an alternative to American Joint Committee on Cancer (AJCC) N stage, with superior prognostic value. The utility of LNR in Middle Eastern Papillary thyroid carcinoma (PTC) remains unknown. Therefore, we retrospectively analyzed a large cohort of 1407 PTC patients for clinico-pathological associations of LNR.

Methods: Receiver operating characteristics (ROC) curve was used to determine the cut-off for LNR. We also performed multivariate logistic regression analysis to determine whether LNR or AJCC N stage was superior in predicting recurrence in PTC.

Results: Based on ROC curve analysis, a cut-off of 0.15 was chosen for LNR. High LNR was significantly associated with adverse clinico-pathological characteristics such as male sex, extrathyroidal extension, lymphovascular invasion, multifocality, bilateral tumors, T4 tumors, lateral lymph node (N1b) involvement, distant metastasis, advanced tumor stage, ATA high risk category and tumor recurrence. On multivariate analysis, we found that LNR was a better predictor of tumor recurrence than AJCC N stage (Odds ratio: 1.96 vs. 1.30; p value: 0.0184 vs. 0.3831). We also found that LNR combined with TNM stage and ATA risk category improved the prediction of recurrence-free survival, compared to TNM stage or ATA risk category alone.

Conclusions: The present study suggests LNR is an independent predictor of recurrence in Middle Eastern PTC. Integration of LNR with 8th edition AJCC TNM staging system and ATA risk stratification will improve the accuracy to predict recurrence in Middle Eastern PTC and help in tailoring treatment and surveillance strategies in these patients.

Citation Format: Sandeep K. Parvathareddy, Abdul K. Siraj, Zeeshan Qadri, Saeeda O. Ahmed, Nabil Siraj, Felisa DeVera, Padmanaban Annaiyappanaidu, Maria A. Sabido, Wael Haqawi, Hassan Aldossari, Khawla S. Al-Kuraya. Lymph node ratio is superior to AJCC N stage for predicting recurrence in papillary thyroid carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5177.

Abstract 5280: TERT promoter mutations are an independent predictor of distant metastasis in Middle Eastern papillary thyroid microcarcinoma

Background: Papillary thyroid microcarcinomas (PTMCs) have been attributed to the recent increased incidence of thyroid cancer. Although indolent, a subset of PTMC could potentially develop distant metastasis (DM). This study aimed to evaluate the clinico-pathological features and molecular characteristics of PTMC and identify the risk factors for DM in PTMC patients from Middle Eastern ethnicity.

Methods: We retrospectively analyzed 210 patients with histologically confirmed PTMC. Clinico-pathological associations for DM, BRAF mutation and TERT mutation were analyzed successfully in 184 patients. Multivariate analysis was performed using Cox proportional hazards model and logistic regression analysis.

Results: Among the PTMC patients included in this cohort, DM was noted in 6.0%(11/184), whereas tumor relapse occurred in 29/184 (15.8%). Of the 11 cases with DM, lung metastasis occurred in 8 cases, bone metastasis in 2 cases and brain metastasis in 1 case. Presence of extrathyroidal extension and older age were significantly associated with DM. Molecular analysis showed BRAF V600E mutations to be the most frequent, being detected in 45.7% (84/184). TERT promoter mutations were detected in 16 (8.7%) cases and were significantly associated with DM and shorter metastasis-free survival in multivariate analysis.

Conclusions: Our study indicates a surprisingly high frequency of TERT promoter mutation in Saudi patients with PTMC. Identifying TERT promoter mutations as an independent predictor of DM in patients with microcarcinoma could explain the inherent aggressive nature of PTMC from Middle Eastern ethnicity and magnify its role in patient risk stratification, which might help in improving therapeutic strategy for these patients.

Citation Format: Saeeda Omer Ahmed, Abdul K. Siraj, Sandeep K. Parvathareddy, Kaleem Iqbal, Zeeshan Qadri, Maha Al-Rasheed, Sarah Siraj, Saravanan Thangavel, Roxanne Diaz, Allianah Benito, Ingrid F. Victoria, Khawla S. AlKuraya. TERT promoter mutations are an independent predictor of distant metastasis in Middle Eastern papillary thyroid microcarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5280.

Abstract 5839: Exome sequencing revealed comparable frequencies of RNF43 mutations and BRAF mutations in Middle Eastern colorectal cancer

Mutation-induced activation of Wnt-β Catenin signaling is a frequent event in CRC. The E3 ubiquitin ligase, RNF43, has been reported to negatively regulate the Wnt signaling pathway. Although, RNF43 mutations are frequently seen in CRC, its role in CRC from Middle Eastern ethnicity remains unclear. Therefore, we conducted this study to assess the frequency of RNF43 mutations, the clinico-pathological and molecular associations in two independent cohorts of Middle Eastern CRC. Exome sequencing was utilized to identify the somatic mutations in RNF43 gene and in known CRC driver genes including APC, TP53, KRAS, BRAF and NRAS among 113 CRC cases of discovery cohort. In validation cohort of 107 CRC cases, Sanger sequencing was employed to detect the mutations in exon 2, 4, 8 and 9 in RNF43 gene while Targeted capture sequencing was conducted to identify the mutations in entire region of APC gene and hotspot regions of KRAS, BRAF, NRAS and TP53 genes. RNF43 somatic mutations were found in 5.9% (13/220) of the entire CRC cohort, which is similar in frequency to BRAF mutations, which were identified in 3.6% (8/220). The mutations in other known driver genes including APC, TP53, KRAS and NRAS were observed in 58.2% (128/220), 50.9% (112/220), 46.4% (102/220) and 2.7% (6/220) cases, respectively, in all 220 tumors examined. However, no significant association between RNF43 mutations and BRAF mutations was seen. RNF43 was found to be inversely correlated to APC and TP53 mutations. Clinico-pathological analysis showed a strong association of RNF43 mutations with right sided and sporadic deficient mismatch repair (dMMR) CRC. No association was identified between RNF43 mutation and other clinico-pathological features such as age, tumor histological subtype, tumor grade or patients’ prognosis. Multivariate logistic regression analysis revealed that dMMR status (Odds ratio = 5.43; 95% confidence interval = 1.12 - 26.32; p = 0.0356) and wild type APC (Odds ratio = 4.77; 95% confidence interval = 1.51 - 19.77; p = 0.0312) were independent predictors of RNF43 mutation. Our results revealed that RNF43 mutations do occur in CRC from Middle Eastern ethnicity at comparable frequencies with BRAF mutations and represent a distinct molecular subtype which further enhance our understanding of how different mutational subsets of Wnt tumor suppressor genes link to distinct tumor characteristics, which might be considered for treatment strategies for CRC patients.

Citation Format: Rong Bu, Abdul K. Siraj, Tariq Masoodi, Sandeep Kumar Parvathareddy, Kaleem Iqbal, Allianah D. Benito, Sarah Siraj, Nabil Siraj, Maha Al Rasheed, Saeeda O. Ahmed, Wael AL-Haqaw, Maria Angelita Sabido, Mark Ranier Diaz, Padmanaban Annaiyappanaidu, Khawla S. Al-Kuraya. Exome sequencing revealed comparable frequencies of RNF43 mutations and BRAF mutations in Middle Eastern colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5839.

Abstract 5178: Multifocality is an independent predictor of regional lymph node metastasis in Middle Eastern papillary thyroid carcinoma

Background: Papillary thyroid carcinoma (PTC) is treatable, with favorable prognosis and very low disease-specific mortality. However, PTC recurrence is relatively common in loco-regional and distant sites. Although multifocality is a common occurrence in PTC, its prognostic impact remains controversial. In addition, data on prevalence and prognostic significance of multifocality in PTC from Middle Eastern ethnicity is unknown. Therefore, the aim of this study was to investigate the prognostic value of multifocality in PTC larger than 1cm and papillary thyroid microcarcinoma (PTMC) in our center.

Methods: A cohort of 1515 patients who underwent total thyroidectomy were retrospectively reviewed. Aggressive histopathologic variants of PTC were excluded to avoid their potential confounding effect on clinical outcomes. We identified 1087 patients who had PTC with primary tumor exceeding 1cm and 150 patients with PTMC, with medium follow up of 9.2 years. In each group, we compared patients with unifocal and multifocal disease. Clinico-pathological and molecular correlations were analyzed. Logistic regression analysis was used to assess the relation between multifocal tumors and lymph node metastasis.

Results: The incidence of multifocality in PTC larger than 1cm was 48.3% (525/1087), whereas it was 38.7% (58/150) in PTMCs. In patients with PTC &gt; 1cm, multifocality was significantly associated with aggressive markers such as extrathyroidal extension (p &lt; 0.0001), lymphovascular invasion (p = 0.0047), lymph node (LN) metastasis (p = 0.0006), distant metastasis (p = 0.0305) and BRAF mutation (p = 0.0113). In analogous analysis of patients with PTMC, multifocality was significantly associated with extrathyroidal extension (p &lt; 0.0001), LN metastasis (p = 0.0005) and BRAF mutation (p = 0.0006). In both sub-groups, disease recurrence and overall survival did not differ between unifocal and multifocal group. Multivariate analysis showed that multifocality was an independent predictor of LN metastasis (Odds ratio (OR) = 1.31; 95% confidence interval (CI) = 1.00 - 1.71; p = 0.0472 for PTC &gt; 1cm and OR = 1.88; 95% CI = 1.00 - 3.54; p = 0.0491 for PTMC).

Conclusions: Tumor multifocality is frequently observed in Middle Eastern PTC and PTMC and is a predictive factor for LN metastasis in PTC. Given the predictive value of multifocality in Middle Eastern ethnicity, aggressive therapy and intensive follow-up should be considered for both PTC and PTMC with multifocality. Regional LN metastasis should be closely monitored and prophylactic central lymph node dissection could be considered in these patients.

Citation Format: Pratheeshkumar Poyil, Abdul K Siraj, Sandeep Kumar Parvathareddy, Divya Padmaja, Saravanan Thangavel, Rafia Begum, Roxanne Diaz, Khadija Al-Obaisi, Khawla S. Al-Kuraya. Multifocality is an independent predictor of regional lymph node metastasis in Middle Eastern papillary thyroid carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5178.

APOBEC SBS13 Mutational Signature-A Novel Predictor of Radioactive Iodine Refractory Papillary Thyroid Carcinoma

Standard surgery followed by radioactive iodine (131I, RAI) therapy are not curative for 5−20% of papillary thyroid carcinoma (PTC) patients with RAI refractory disease. Early predictors indicating therapeutic response to RAI therapy in PTC are yet to be elucidated. Whole-exome sequencing was performed (at median depth 198x) on 66 RAI-refractory and 92 RAI-avid PTCs with patient-matched germline. RAI-refractory tumors were significantly associated with distinct aggressive clinicopathological features, including positive surgical margins (p = 0.016) and the presence of lymph node metastases at primary diagnosis (p = 0.012); higher nonsilent tumor mutation burden (p = 0.011); TERT promoter (TERTp) mutation (p < 0.0001); and the enrichment of the APOBEC-related single-base substitution (SBS) COSMIC mutational signatures 2 (p = 0.030) and 13 (p < 0.001). Notably, SBS13 (odds ratio [OR] 30.4, 95% confidence intervals [CI] 1.43−647.22) and TERTp mutation (OR 41.3, 95% CI 4.35−391.60) were revealed to be independent predictors of RAI refractoriness in PTC (p = 0.029 and 0.001, respectively). Although SBS13 and TERTp mutations alone highly predicted RAI refractoriness, when combined, they significantly increased the likelihood of predicting RAI refractoriness in PTC. This study highlights the APOBEC SBS13 mutational signature as a novel independent predictor of RAI refractoriness in a distinct subgroup of PTC.

Lymph node ratio is superior to AJCC N stage for predicting recurrence in papillary thyroid carcinoma

OBJECTIVE

Recently, lymph node ratio (LNR) has emerged as an alternative to American Joint Committee on Cancer (AJCC) N stage, with superior prognostic value. The utility of LNR in Middle Eastern papillary thyroid carcinoma (PTC) remains unknown. Therefore, we retrospectively analyzed a large cohort of 1407 PTC patients for clinicopathological associations of LNR.

METHODS

Receiver operating characteristics (ROC) curve was used to determine the cut-off for LNR. We also performed multivariate logistic regression analysis to determine whether LNR or AJCC N stage was superior in predicting recurrence in PTC.

RESULTS

Based on ROC curve analysis, a cut-off of 0.15 was chosen for LNR. High LNR was significantly associated with adverse clinicopathological characteristics such as male sex, extrathyroidal extension, lymphovascular invasion, multifocality, bilateral tumors, T4 tumors, lateral lymph node (N1b) involvement, distant metastasis, advanced tumor stage, American Thyroid Association (ATA) high-risk category and tumor recurrence. On multivariate analysis, we found that LNR was a better predictor of tumor recurrence than AJCC N stage (odds ratio: 1.96 vs 1.30; P value: 0.0184 vs 0.3831). We also found that LNR combined with TNM stage and ATA risk category improved the prediction of recurrence-free survival, compared to TNM stage or ATA risk category alone.

CONCLUSIONS

The present study suggests LNR is an independent predictor of recurrence in Middle Eastern PTC. Integration of LNR with 8th edition AJCC TNM staging system and ATA risk stratification will improve the accuracy to predict recurrence in Middle Eastern PTC and help in tailoring treatment and surveillance strategies in these patients.

Risk Factors for Central Lymph Node Metastases and Benefit of Prophylactic Central Lymph Node Dissection in Middle Eastern Patients With cN0 Papillary Thyroid Carcinoma

Background

Prophylactic central lymph node dissection (PCLND) for adult patients with papillary thyroid carcinoma (PTC) is still a matter of debate. Data on incidence, risk and benefits of PCLND in Middle Eastern patients is lacking. Therefore, we aimed to identify the incidence and predictive clinico-pathological and molecular marker of PCLND in adult patients with clinically node negative (cN0) Middle Eastern PTC.

Methods

This retrospective study included 942 adult Middle Eastern patients with cN0 PTC who underwent total thyroidectomy (TT) or TT+PCLND. Clinico-pathological associations of central lymph node metastasis (CLNM) were assessed. Multivariate analysis was performed using logistic regression and Cox proportional hazards model.

Results

213 patients underwent PCLND and 38.0% (81/213) had positive CLNM. Multivariate analysis demonstrated age ≤55 years (Odds Ratio (OR) = 7.38; 95% Confidence Interval (CI) = 1.59 – 34.31; p = 0.0108), tumor bilaterality (OR = 3.01; 95% CI = 1.01 – 9.21; p = 0.0483), lymphovascular invasion (OR = 2.92; 95% CI = 1.18 – 7.23; p = 0.0206) and BRAF mutation (OR = 3.24; 95% CI = 1.41 – 7.49; p = 0.0058) were independent predictors of CLNM in adult PTC. Furthermore, patients who underwent PCLND showed significant association with improved recurrence-free survival (RFS; p = 0.0379). Multivariate analysis demonstrated that PCLND was an independent predictor of improved recurrence-free survival.

Conclusions

cN0 Middle Eastern PTC patients treated with PCLND showed a significantly better prognosis. PCLND was effective in improving RFS in Middle Eastern PTC patients and should be encouraged for patients with potential risk factors for CLNM.

Male Sex Is an Independent Predictor of Recurrence-Free Survival in Middle Eastern Papillary Thyroid Carcinoma

BACKGROUND

Disparity between sexes with regard to incidence, disease aggressiveness, and prognosis has been documented in several cancers. Although various reports have documented the association between male sex and aggressive papillary thyroid carcinoma (PTC), the prognostic impact of sex on PTC has been inconsistent. The role of sex in PTC aggressiveness and outcome in Middle Eastern PTC remains unknown. Therefore, our study retrospectively analyzed the data of a large cohort of Middle Eastern PTC patients to address this issue.

METHODS

We compared men and women with respect to clinico-pathological characteristics, disease persistence, structural recurrence, risk stratification, and prognosis. We included 1,430 patients-1,085 (75.9%) women and 345 (24.1%) men.

RESULTS

The median follow-up was 9.3 years. At diagnosis, 27% (93/345) of men were ≥55 years, compared with 17.8% (193/1085) of women (p = 0.0003). Men had significantly more advanced disease at presentation: higher stage (p = 0.0074), larger tumor size (p = 0.0069), higher rates of lymphovascular invasion (p = 0.0129), extrathyroidal extension (p = 0.0086), regional lymph node metastasis (p = 0.0279), and distant metastasis (p = 0.0101). There was a higher rate of recurrence (p < 0.0001) and TERT mutations (p = 0.0003) in male PTC patients than in female patients. Additionally, radioiodine refractoriness was higher in male PTC patients (p = 0.0014). In multivariate analysis, male sex was an independent prognostic factor for poor recurrence-free survival (RFS) (hazard ratio = 1.58; 95% confidence interval = 1.20-2.06; p = 0.0011).

CONCLUSIONS

Men with PTC are more likely to present with more advanced and aggressive disease. Importantly, male sex was an independent prognostic factor for RFS. Thus, men may benefit from more aggressive management and therapeutic interventions.

X-linked inhibitor of apoptosis protein (XIAP) predicts disease-free survival in BRAFV600E mutant papillary thyroid carcinoma in middle eastern patients

BACKGROUND

X-linked inhibitor of apoptosis (XIAP) is the most potent caspase inhibitory IAP family member and its over-expression is implicated in aggressive behavior of various solid tumors, including papillary thyroid carcinoma (PTC). BRAFV600E mutation is the most common oncogenic event in PTC and is also known to be associated with aggressive clinico-pathological characteristics. In this study, we investigated the prevalence of XIAP expression in more than 1600 PTCs from Middle Eastern ethnicity and its prognostic value to predict disease-free survival (DFS), in combination with the BRAFV600E mutation.

METHODS

Clinical data, XIAP expression by immunohistochemistry and BRAF mutation status were analyzed in 1640 Saudi PTC patients seen at our institute between 1988 - 2020.

RESULTS

BRAFV600E mutation was found in 910 of 1640 patients (55.5%) and was significantly correlated with older age, extrathyroidal extension, bilaterality, multifocality and lymph node metastasis, but was not an independent predictor of DFS. XIAP was over-expressed in 758 of 1640 (46.2%) and was associated with aggressive clinico-pathological features. It was also found to be an independent prognostic marker for DFS (HR = 1.28, 95% CI = 1.02 - 1.60, P = 0.0342). XIAP overexpression was correlated with presence of BRAFV600E mutation in PTC patients. Interestingly, we found the ability to predict shorter DFS was 2.7-fold higher in PTCs with over-expression of XIAP and BRAFV600E mutation compared to patients with high XIAP and wild-type BRAFV600E status (HR = 2.74, 95% CI = 2.19 - 3.44, p < 0.0001).

CONCLUSION

XIAP expression is an independent predictor of prognosis in Middle Eastern PTC patients. Combination of XIAP expression and BRAFV600E mutation can synergistically improve the DFS prediction in PTC patients, which may help clinicians to establish the most appropriate initial care and long-term surveillance strategies.

TERT Promoter Mutations Are an Independent Predictor of Distant Metastasis in Middle Eastern Papillary Thyroid Microcarcinoma

BACKGROUND

Papillary thyroid microcarcinomas (PTMCs) have been attributed to the recent increased incidence of thyroid cancer. Although indolent, a subset of PTMC could potentially develop distant metastasis (DM). This study aimed to evaluate the clinico-pathological features and molecular characteristics of PTMC and identify the risk factors for DM in PTMC patients from Middle Eastern ethnicity.

METHODS

We retrospectively analyzed 210 patients with histologically confirmed PTMC. Clinico-pathological associations for DM, BRAF mutation and TERT mutation were analyzed successfully in 184 patients. Multivariate analysis was performed using Cox proportional hazards model and logistic regression analysis.

RESULTS

Among the PTMC patients included in this cohort, DM was noted in 6.0% (11/184), whereas tumor relapse occurred in 29/184 (15.8%). Of the 11 cases with DM, lung metastasis occurred in 8 cases, bone metastasis in 2 cases and brain metastasis in 1 case. Presence of extrathyroidal extension and male sex were significantly associated with DM. Molecular analysis showed BRAF V600E mutations to be the most frequent, being detected in 45.7% (84/184). TERT promoter mutations were detected in 16 (8.7%) cases and were significantly associated with DM and shorter metastasis-free survival in multivariate analysis.

CONCLUSIONS

Our study indicates a surprisingly high frequency of TERT promoter mutation in Saudi patients with PTMC. Identifying TERT promoter mutations as an independent predictor of DM in patients with microcarcinoma could explain the inherent aggressive nature of PTMC from Middle Eastern ethnicity and magnify its role in patient risk stratification, which might help in improving therapeutic strategy for these patients.

Tumor size is an independent negative prognostic factor for event free survival in children with differentiated thyroid cancer

BACKGROUND

The incidence of pediatric differentiated thyroid carcinoma (DTC) is increasing. Despite the advanced disease at presentation, the overall prognosis of DTC in children is excellent. The aim of this study is to investigate the risk stratifying factors for event free survival (EFS) of pediatric DTC from Middle Eastern ethnicity.

METHODS

Eighty-eight patients aged ≤18 years with diagnosis of primary DTC were retrospectively analyzed. Cox proportional hazards model were used to calculate Hazard Ratios (HR) and Kaplan-Meier analysis were conducted to investigate EFS.

RESULTS

Eighty-eight (23 males and 65 females) pediatric DTCs who underwent surgery and radioactive iodine therapy had been reported (median age at diagnosis 15 years; range 5.9-17.9), with lymph node metastasis (LNM) noted in 70.5% and distant metastasis in 13.6%. Mean follow-up was 8.4 years. Ten-year overall survival rate was 98.4% while 10-year EFS was 79.2%. EFS was negatively impacted by the presence of LNM, distant metastasis and tumor size >4cm. American Thyroid Association risk stratification did not impact EFS in our cohort. Multivariate analysis revealed tumor size >4cm (HR = 5.34; 95% confidence interval (CI) = 1.36 - 20.22; p = 0.0177) and distant metastasis (HR = 8.73; 95% CI = 1.48 - 60.05; p = 0.0154) as independent negative prognostic factors for EFS.

CONCLUSIONS

Primary tumor size and the presence of distant metastasis at diagnosis are the only independent prognostic risk factors for EFS in pediatric DTC in Middle Eastern ethnicity. Children with tumor size over 4cm had poor EFS, which may justify the need of more aggressive treatment and frequent follow-up.

Microscopic Extrathyroidal Extension Results in Increased Rate of Tumor Recurrence and Is an Independent Predictor of Patient’s Outcome in Middle Eastern Papillary Thyroid Carcinoma

Background

Papillary Thyroid Cancer (PTC) is the most common endocrine malignancy, with recurrence rate as high as 30%. A great deal of controversy surrounds the significance of microscopic extrathyroidal extension (m-ETE) as a prognostic factor. The most recent edition (8^th) of American Joint Committee on Cancer (AJCC) staging system has removed m-ETE from the definition of pT3, which suggests that m-ETE may lack prognostic impact in PTC patients. Moreover, data about m-ETE prevalence and clinical impact on Middle Eastern PTC remains unknown. We therefore investigate the prevalence of m-ETE and its clinico-pathological correlation and prognostic impact in Middle Eastern PTC. We also compared the AJCC 7^th and 8^th staging systems and their prognostic performance.

Methods

PTCs from 1430 consecutive adult (> 18 years) patients from single tertiary care hospital were included in this study. A retrospective analysis of PTC patients’ survival and recurrence were compared between AJCC 8^th and AJCC 7^th staging systems using Proportion of Variation Explained (PVE) and Harrell’s C-index.

Results

Median follow up of the study cohort was 9.3 years. 31.2% (446/1430) of patients had m-ETE. In the overall cohort, m-ETE was associated with multiple adverse features such as older age (p < 0.0001), male sex (p = 0.0245), tall cell variant (p < 0.0001), bilateral tumors (p < 0.0001), multifocality (p < 0.0001), lymphovascular invasion (p < 0.0001), lymph node metastasis (p < 0.0001), distant metastasis (p = 0.0166), tumor recurrence (p < 0.0001), radioactive iodine refractoriness (p < 0.0001), BRAF mutation (p < 0.0001) and reduced recurrence-free survival (RFS; HR = 1.75; 95% CI = 1.30 – 2.35; p < 0.0001) irrespective of tumor size. Of the 611 patients with T3 disease based on AJCC 7^th edition, 359 (58.8%) were down-staged in AJCC 8^th edition classification. Overall, the prognostic performance of AJCC 8^th edition was inferior to AJCC 7^th on the basis of lower PVE (3.04% vs. 3.73%) and lower C-index (0.40 vs. 0.48).

Conclusions

In Middle Eastern PTC, m-ETE is significantly associated with compromised survival and acts as an independent predictor of RFS. Given these findings, m-ETE should be included in the thyroid cancer treatment guidelines.

Abstract LBA042: Male Sex is an Independent Predictor of Recurrence-Free Survival in Middle Eastern Papillary Thyroid Carcinoma

Background: Disparity between sexes with regards to incidence, disease aggressiveness, and prognosis has been documented in several cancers. Although various reports have documented the association between male sex and aggressive papillary thyroid carcinoma (PTC), the prognostic impact of sex on PTC has been inconsistent. The role of sex in PTC aggressiveness and outcome in Middle Eastern PTC remains unknown. Therefore, our study retrospectively analyzed the data of a large cohort of Middle Eastern PTC patients to address this issue. Methods: We compared men and women with respect to clinico-pathological characteristics, disease persistence, structural recurrence, risk stratification and prognosis. We included 1430 patient - 1085 (75.9%) women and 345 (24.1%) men. Results: The median follow up was 9.5 years. At diagnosis, 27% (93/345) of men were ≥ 55 years, compared with 17.8% (193/1085) of women (p = 0.0003). Men had significantly more advanced disease at presentation: higher stage (p = 0.0074), larger tumor size (p = 0.0069), higher rates of lymphovascular invasion (p = 0.0129), extrathyroidal extension (p = 0.0086), regional lymph node metastasis (p = 0.0279), and distant metastasis (p = 0.0101). There was a higher rate of recurrence (p &lt; 0.0001) and TERT mutations (p = 0.0003) in male PTC patients than in female patients. Additionally, radioiodine refractoriness was higher in male PTC patients (p = 0.0014). In multivariate analysis, male sex was an independent prognostic factor for poor recurrence-free survival (RFS) (Hazard ratio = 1.59; 95% Confidence interval = 1.21 – 2.07; p = 0.0010). Conclusions: Men with PTC are more likely to present with more advanced and aggressive diseases. Importantly, male sex was an independent prognostic factor for RFS. Thus, men may benefit from more aggressive management and therapeutic interventions.

Citation Format: KHAWLA S. AL-KURAYA, Sandeep Kumar Parvathareddy, Abdul K Siraj, Felisa De Vera, Padmanaban Annaiyappanaidu, Saeeda O. Ahmed, Saif S. Al-Sobhi, Fouad Al-Dayel. Male Sex is an Independent Predictor of Recurrence-Free Survival in Middle Eastern Papillary Thyroid Carcinoma [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr LBA042.

Loss of ZNF677 expression is a predictive biomarker for lymph node metastasis in Middle Eastern Colorectal Cancer

Zinc-finger proteins are transcription factors with a “finger-like” domain that are widely involved in many biological processes. The zinc-finger protein 677 (ZNF677) belongs to the zinc-finger protein family. Previous reports have highlighted the tumor suppressive role of ZNF677 in thyroid and lung cancer. However, its role in colorectal cancer (CRC) has not been explored. ZNF677 protein expression was analyzed by immunohistochemistry in a large cohort of 1158 CRC patients. ZNF677 loss of expression was more frequent in CRC tissues (45.3%, 525/1158), when compared to that of normal tissue (5.1%, 11/214) (p < 0.0001) and was associated with mucinous histology (p = 0.0311), advanced pathological stage (p < 0.0001) and lymph node (LN) metastasis (p = 0.0374). Further analysis showed ZNF677 loss to be significantly enriched in LN metastatic CRC compared to overall cohort (p = 0.0258). More importantly, multivariate logistic regression analysis showed that ZNF677 loss is an independent predictor of LN metastasis in CRC (Odds ratio = 1.41; 95% confidence interval 1.05–1.87; p = 0.0203).The gain- and loss-of-function studies in CRC cell lines demonstrated that loss of ZNF677 protein expression prominently increased cell proliferation, progression of epithelial-mesenchymal transition and conferred chemoresistance, whereas its overexpression reversed the effect. In conclusion, loss of ZNF677 protein expression is common in Middle Eastern CRC and contributes to the prediction of biological aggressiveness of CRC. Therefore, ZNF677 could not only serve as a marker in predicting clinical prognosis in patient with CRC but also as a potential biomarker for personalized targeted therapy.

Loss of ZNF677 Expression Is an Independent Predictor for Distant Metastasis in Middle Eastern Papillary Thyroid Carcinoma Patients

Thyroid cancer incidence has increased in recent decades. Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer. Approximately 30% of PTC patients develop recurrence or distant metastasis and tend to have poor prognosis. Therefore, the identification of targetable biomarkers in this subset of patients is of great importance. Accumulating evidence indicates that zinc finger protein 677 (ZNF677), which belongs to the zinc finger protein family, is an important effector during the progression of multiple malignancies. However, its role in Middle Eastern PTC patients has not been fully illustrated. Here, we uncovered the molecular mechanism and the clinical impact of ZNF677 expression in a large cohort of more than 1200 Middle Eastern PTC and 15 metastatic tissues. We demonstrated that ZNF677 is frequently downregulated in primary PTC (13.6%, 168/1235) and showed that complete loss of expression of ZNF677 is significantly associated with aggressive clinico-pathological markers such as extrathyroidal extension (p = 0.0008) and distant metastases (p < 0.0001). We also found a significantly higher incidence of ZNF677 loss in primary tumors with distant metastases (33.3%; p < 0.0001) as well as in distant metastatic tissues (46.7%; p = 0.0002) compared to the overall cohort (13.6%). More importantly, PTC with loss of ZNF677 expression showed significantly lower metastasis-free survival (p = 0.0090). Interestingly, on multivariate logistic regression analysis, ZNF677 loss was an independent predictor of distant metastasis in PTC (Odds ratio = 2.60, 95% Confidence interval = 1.20–5.62, p = 0.0155). In addition, we found a significant association between ZNF677 loss and phospho-AKT expression (p < 0.0001). Our functional molecular results suggest that ZNF677 acts as a tumor suppressor, mediating its effect by inhibiting AKT phosphorylation. Taken together, our results highlight the pivotal role played by ZNF677 during carcinogenesis and metastasis formation in Middle Eastern PTC patients.

Abstract 1963: High expression of Cyclin D1 is an independent marker for favorable prognosis in Middle Eastern breast cancer

Cyclin D1 protein regulates cell cycle progression which is mediated by its interactions with cyclin-dependent kinases. Over-expression of Cyclin D1 has been observed in several human cancers. This study was conducted to evaluate Cyclin D1 expression in a large cohort of Middle Eastern breast cancers and determine its prognostic significance. Cyclin D1 expression was assessed immunohistochemically and its association with clinico-pathological parameters was analyzed. Cyclin D1 was over-expressed in 59.4% (596/1003) of cases and significantly associated with a subset of breast cancers having favorable prognostic features such as low grade (p &lt; 0.0001), low stage (p = 0.0276), estrogen receptor positive (p &lt; 0.0001) and progesterone receptor positive (p &lt; 0.0001) tumors. An inverse association was found with triple negative breast cancers (p &lt; 0.0001). More importantly, Cyclin D1 expression was an independent predictor of favorable overall survival in our cohort (Hazard ratio = 0.69; 955 confidence interval = 0.48 - 0.98; p = 0.0405). Also, tumors that highly expressed cyclin D1 had a longer recurrence free survival. However, recurrence free survival was only significant in univariate analysis. In conclusion, our results reinforced the role of cyclin D1 in breast cancer pathology and revealed its expression as a valuable independent prognostic indicator for breast cancer from Middle Eastern ethnicity.

Citation Format: Khawla S. Al-Kuraya, Abdul K. Siraj, Sandeep K. Parvathareddy, Sarah Siraj, Saud Azam, Padmanaban Annaiyappanaidu, Maria Angelita Sabido, Mark Ranier Diaz. High expression of Cyclin D1 is an independent marker for favorable prognosis in Middle Eastern breast cancer [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 1963.

Abstract 3192: PD-L1 is an independent prognostic marker in Middle Eastern PTC and its expression is upregulated by BRAFV600E mutation

Background: PD-L1 inhibition is a promising therapeutic target whose efficacy has been demonstrated in several cancers. This study was conducted to evaluate the prognostic significance of PD-L1 expression in a large cohort of Middle Eastern PTC patients and to explore correlation of PD-L1 and BRAFV600E mutations in PTC tumors and cell lines.

Methods: Immunohistochemistry was performed to assess PD-L1 protein expression in PTC. We further conducted in vitro analysis to investigate the role of PD-L1 in regulating BRAFV600E in PTC cell lines.

Results: PD-L1 over-expression was noted in 32.4% (473/1458) of cases and significantly associated with adverse clinico-pathological parameters such as tall cell variant, extra-thyroidal extension and lymph node metastasis. Importantly, PD-L1 was found to be an independent poorer prognostic marker. We also found PD-L1 to be significantly associated with BRAF mutation and patients with co-existing PD-L1 over-expression and BRAF mutation had a poor disease-free survival compared to patients with BRAF mutation alone. In vitro analysis showed high expression of PD-L1 in BRAF mutated PTC cell lines compared to BRAF wild-type cell line. Inhibition of BRAF using vemurafenib induced PD-L1 expression in BRAF mutated cell lines without affecting cell growth. Knockdown of PD-L1 in BRAF mutated cell lines significantly decreased the cell growth and induced apoptosis.

Conclusion: Our data suggests that PD-L1 might represent a useful prognostic marker in Middle Eastern PTC and PD-L1 inhibition could be a potential therapeutic option for aggressive PTC cancers, such as tall cell variant, BRAF mutation positive patients that are unresponsive to standard treatment.

Citation Format: Tariq Masoodi, Abdul K. Siraj, Sandeep Kumar Parvathareddy, Poyil Pratheeshkumar, Sasidharan Padmaja Divya, Rafia Begum, Roxanne Diaz, Thangavel Saravanan, Khadija Al-Obaisi, Sarah Siraj, Saud Azam, Zeeshan Qadri, Khawla S. Al-Kuraya. PD-L1 is an independent prognostic marker in Middle Eastern PTC and its expression is upregulated by BRAFV600E mutation [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 3192.

Abstract 730: Annual hazard rate of recurrence in Middle-Eastern papillary thyroid cancer over a long-term follow-up

Predicting the pattern of recurrence is necessary to establish optimal surveillance and treatment strategies. We identified patient population that remain at risk for an event and clarify changes in the hazard rate (HR) for tumor recurrence overtime in Middle Eastern patients with Papillary Thyroid Cancer (PTC). Data for 1201 PTC patients from single institute with median follow-up of 9.5 years were analyzed. Estimated HR were plotted overtime for the entire cohort, as well as for radioactive iodine (RAI) ablation in patients separately. The changes in risk were further analyzed according to clinical variable and factors predictive of early (≤ 5years) and late (&gt;5 years) recurrence were explored using Cox regression analysis. Tumor recurrence was noted in 18.4% (221/1201) patients. The annualized hazard of PTC recurrence was highest during the first 5 years (2.8%), peaking between 1 - 2 years (3.7%), with a second smaller peak between 13 - 14 years (3.2%). Patients receiving RAI therapy had a lower hazard of recurrence compared to those who did not receive RAI therapy (1.5% vs 2.7%, p = 0.0001). Importantly, this difference was significant even in the intermediate-risk PTC patients (0.7% vs 2.3%; p = 0.0001). Interestingly, PTC patients who were male, aged ≥ 55 years, with lymph node involvement and advanced stage disease were still at high risk for late recurrence. In conclusion, we confirmed the validity of double-peaked time-varying pattern for risk of recurrence in Middle-Eastern PTC patients. Furthermore, according to the time distribution of recurrence hazard, we could formulate individualized treatment and surveillance plans in PTC patients.

Citation Format: Abdul K. Siraj, Sandeep K. Parvathareddy, Zeeshan Qadri, Saud Azam, Felisa De Vera, Maha Al-Rasheed, Wael Haqawi, Hassan AlDossari, Khawla S. Al-Kuraya. Annual hazard rate of recurrence in Middle-Eastern papillary thyroid cancer over a long-term follow-up [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 730.

Abstract 1176: CHD4 predicts aggressiveness in PTC patients and promotes cancer stemness and EMT in PTC cells

Papillary thyroid carcinoma (PTC) is the most common histologic subtype, accounting for nearly 90% of thyroid cancer. Chromodomain-helicase-DNA-binding protein 4 (CHD4), a core subunit of the nucleosome remodeling and deacetylation (NuRD) complex is highly expressed in several cancers. However, its role in the pathogenesis and progression of PTC has not been investigated. Immunohistochemistry was performed to assess CHD4 protein expression in PTC using a tissue microarray. We also performed in vitro analysis to investigate the role of CHD4 in regulating cancer stemness and EMT in PTC cells. CHD4 overexpression was observed in 45.3% (650/1436) of PTCs, and was associated with aggressive clinico-pathological parameters and worse outcome. Functional analysis using PTC cell lines showed that forced expression of CHD4 promoted cell proliferation, spheroid growth, migration, invasion, and progression of epithelial to mesenchymal transition (EMT) in PTC cells whereas its knockdown reversed the effect. Methylation of E-cadherin was associated with loss of expression in CHD4 expressing cells, while CHD4 depletion reactivated E-cadherin expression. Most importantly, knockdown of mesenchymal transcriptional factors, Snail1 or Zeb1, attenuated the spheroid growth in CHD4 expressing PTC cells, showing a potential link between EMT activation and stemness maintenance in PTC. These findings suggest that CHD4 might be a promising therapeutic target in the treatment of patients with an aggressive subtype of PTC.

Citation Format: Pratheeshkumar Poyil, Abdul K. Siraj, Sasidharan Padmaja Divya, Sandeep Kumar Parvathareddy, Roxanne Diaz, Rafia Begum, Khadija Al-Obaisi, Saravanan Thangavel, Saif S. Al-Sobhi, Fouad Al-Dayel, Khawla S. Al-Kuraya. CHD4 predicts aggressiveness in PTC patients and promotes cancer stemness and EMT in PTC cells [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 1176.

Abstract 729: Prognostic significance of COX-2 over-expression in BRAF mutated Middle Eastern PTC

The cyclooxygenase-2 (COX-2) - prostaglandin E2 (PGE2) pathway has been implicated in carcinogenesis with BRAF mutation shown to promote PGE2 synthesis. This study was conducted to evaluate COX-2 expression in a large cohort of Middle Eastern Papillary Thyroid Carcinoma (PTC) and further evaluate the prognostic significance of COX-2 expression in strata of BRAF mutation status. BRAF mutation analysis was performed by Sanger sequencing and COX-2 expression was evaluated immunohistochemically using tissue microarray. COX-2 over-expression was noted in 43.2% (567/1314) of cases and was significantly associated with poor prognostic markers such as extra-thyroidal extension, lymph node metastasis and higher tumor stage. COX-2 was also an independent predictor of poor disease-free survival (DFS). Most notably, the association of COX-2 expression with DFS differed by BRAF mutation status. COX-2 over-expression was associated with poor DFS in BRAF mutant but not BRAF wild-type PTCs with the multivariate-adjusted hazard ratio of 2.10 (95% CI = 1.52 - 2.92; p &lt; 0.0001) for COX-2 over-expressed tumors in BRAF mutant PTC. In conclusion, the current study shows that COX-2 plays a key role in prognosis of PTC patients. Furthermore, a significant association of COX-2 expression with poor DFS was noted in BRAF mutated tumors. Our data suggests the potential therapeutic role of COX-2 inhibition in patients with BRAF mutated PTC.

Citation Format: Rong Bu, Sandeep K. Parvathareddy, Abdul K. Siraj, Padmanaban Annaiyappanaidu, Kaleem Iqbal, Maha Al Rasheed, Wael Haqawi, Khawla S. Al-Kuraya. Prognostic significance of COX-2 over-expression in BRAF mutated Middle Eastern PTC [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 729.

Abstract 2425: Prevalence of NTRK fusions and clinico-pathological characteristics of Middle Eastern papillary thyroid cancer revealed enrichment in BRAF wild-type PTC

Fusions involving neurotrophic tyrosine receptor kinase (NTRK) are known oncogenic drivers in a broad range of tumor types. It recently gained attention as predictor of targeted therapy, since selective NTRK inhibitor are now approved in US and Europe for patients with solid tumor harboring gene fusions. However, estimation of NTRK gene fusion/alteration frequency and its clinico-pathological characteristics in papillary thyroid cancer (PTC) is limited, especially in a population with high incidence for PTC like Middle Eastern population. This study aims to characterize the NTRK gene fusion frequency using FISH analysis and investigate the utility of pan-Trk immunohistochemistry as predictor of NTRK fusion in a large cohort of Middle Eastern PTC. FISH analysis for NTRK gene fusions as well as immunohistochemical (IHC) staining was conducted on a cohort of 315 Middle Eastern PTC. Correlation of NTRK with clinico-pathological markers and patient outcome were determined. 6.0% (19/315) patients were identified with NTRK gene fusions and significantly associated with pediatric PTC, lymph node metastasis and BRAF wild-type. Pan-Trk IHC was positive in 9.2% (29/315) and significantly associated with NTRK gene fusion with a sensitivity of 73.7% and specificity of 94.9% in this cohort. In conclusion, this study confirms the presence of NTRK fusions in Middle Eastern PTC and mostly enriched in BRAF wild-type and pediatric age group and propose the usefulness of IHC to screen for PTC patients with NTRK fusion that might benefit from TRK inhibitors.

Citation Format: Abdul K. Siraj, Rong Bu, Sandeep K. Parvathareddy, Yan Kong, Padmanaban Annaiyappanaidu, Saeeda O. Ahmed, Maha Al-Rasheed, Khawla S. Al-Kuraya. Prevalence of NTRK fusions and clinico-pathological characteristics of Middle Eastern papillary thyroid cancer revealed enrichment in BRAF wild-type PTC [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 2425.

Cyclin-dependent kinase 9 (CDK9) predicts recurrence in Middle Eastern epithelial ovarian cancer

Background

Cyclin-dependent kinase 9 (CDK9) has been shown to play an important role in tumorigenesis of several malignancies. However, the expression of CDK9 in ovarian cancer from Middle Eastern ethnicity remains unknown.

Methods

A tissue microarray of 441 epithelial ovarian cancer (EOC) samples was used to study the expression of CDK9 immunohistochemically and their clinico-pathological associations were determined. Cox proportional hazards regression model was used for univariate and multivariate analysis of recurrence-free survival.

Results

CDK9 over-expression was noted in 56.2 % (248/441) of EOCs and was associated with adverse clinico-pathological parameters such as distant metastasis (p < 0.0001), stage IV tumors (p < 0.0001), tumor recurrence (p = 0.0105) and high Ki-67 index (p < 0.0001). Importantly, CDK9 over-expression was an independent predictor of poor recurrence-free survival (Hazard ratio = 1.51; 95 % confidence interval = 1.15–1.98; p = 0.0030). We also found that CDK9 outperforms Ki-67 as a predictor of tumor recurrence in EOC.

Conclusions

Our results show that CDK9 expression correlates with markers of advanced disease in Middle Eastern EOC and is also a prognostic marker. CDK9 overexpression also identifies a subset of patients with highest likelihood of recurrence across the patient cohort. These patients may benefit from additional alternative therapies targeting CKD9.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13048-021-00827-8.

High Expression of Cyclin D1 is an Independent Marker for Favorable Prognosis in Middle Eastern Breast Cancer

Purpose

The cyclin D1 protein regulates cell cycle progression which is mediated by its interactions with cyclin-dependent kinases. Over-expression of cyclin D1 has been observed in several human cancers. This study was conducted to evaluate cyclin D1 expression in a large cohort of Middle Eastern breast cancers and determine its prognostic significance.

Patients and Methods

Cyclin D1 expression was assessed immunohistochemically and its association with clinico-pathological parameters was analyzed in 1003 breast cancer patients.

Results

Cyclin D1 was over-expressed in 59.4% (596/1003) of cases and significantly associated with a subset of breast cancers having favorable prognostic features, such as low grade (p < 0.0001), low stage (p = 0.0276), estrogen receptor (p < 0.0001) and progesterone receptor positive (p < 0.0001) tumors. An inverse association was found with triple negative breast cancers (p < 0.0001). More importantly, cyclin D1 expression was an independent predictor of favorable overall survival in our cohort (hazard ratio = 0.70; 95% confidence interval = 0.50–0.98; p = 0.0395). Also, tumors that highly expressed cyclin D1 had a longer recurrence-free survival. However, this significant association was seen only in univariate analysis. We also found cyclin D1 to be associated with phospho-Rb in luminal subtype of breast cancer and co-expression of both these markers was an independent predictor of luminal A breast cancer.

Conclusion

Our results reinforced the role of cyclin D1 in breast cancer pathology and revealed its expression as a valuable independent prognostic indicator for breast cancer from Middle Eastern ethnicity.

Recurrent Somatic MAP2K1 Mutations in Papillary Thyroid Cancer and Colorectal Cancer

Mitogen-activated protein kinase kinase 1 (MAP2K1) is a dual specificity protein kinase that phosphorylates both threonine and tyrosine residues in ERK. MAP2K1 mutations have been identified in several cancers. However, their role in Middle Eastern papillary thyroid cancer (PTC) and colorectal cancer (CRC) is lacking. In this study, we evaluated the prevalence of MAP2K1 mutations in a large cohort of Middle Eastern PTC and CRC using whole-exome and Sanger sequencing technology. In the discovery cohort of 100 PTC and 100 CRC cases (comprising 50 MAPK mutant and 50 MAPK wildtype cases each), we found one MAP2K1 mutation each in PTC and CRC, both of which were MAPK wildtype. We further analyzed 286 PTC and 289 CRC MAPK wildtype cases and found three MAP2K1 mutant PTC cases and two MAP2K1 mutant CRC cases. Thus, the overall prevalence of MAP2K1 mutation in MAPK wildtype cases was 1.1% (4/336) in PTC and 0.9% (3/339) in CRC. Histopathologically, three of the four MAP2K1 mutant PTC cases were follicular variant and all four tumors were unifocal with absence of extra-thyroidal extension. All the three CRC cases harboring MAP2K1 mutation were of older age (> 50 years) and had moderately differentiated stage II/III tumors located in the left colon. In conclusion, this is the first comprehensive report of MAP2K1 somatic mutations prevalence in PTC and CRC from this ethnicity. The mutually exclusive nature of MAP2K1 and MAPK mutations suggests that each of these mutation may function as an initiating mutation driving tumorigenesis through MAPK signaling pathway.

NTRK fusion analysis reveals enrichment in Middle Eastern BRAF wild-type PTC

OBJECTIVE

Fusions involving neurotrophic tyrosine receptor kinase (NTRK) are known oncogenic drivers in a broad range of tumor types. It recently gained attention as a predictor of targeted therapy since selective NTRK inhibitors are now approved in the US and Europe for patients with solid tumors harboring gene fusions. However, estimation of NTRK gene fusion/alteration frequency and its clinicopathological characteristics in papillary thyroid cancer (PTC) is limited, especially in a population with high incidence for PTC like Middle Eastern population. This study aims to characterize the NTRK gene fusion frequency and investigate the utility of pan-Trk immunohistochemistry (IHC) as predictor of NTRK fusion in a large cohort of Middle Eastern PTC.

METHODS

FISH analysis for NTRK gene fusions and pan-Trk IHC was performed on 315 Middle Eastern PTCs. Correlation of NTRK gene fusion and protein expression with clinicopathological markers and patient outcome were determined.

RESULTS

In our cohort, 6.0% (19/315) patients showed NTRK gene fusions and were significantly associated with pediatric PTC (P = 0.0143), lymph node metastasis (P = 0.0428) and BRAF WT tumors (P < 0.0001). Pan-Trk IHC was positive in 9.2% (29/315) of cases and significantly associated with NTRK fusions, with a sensitivity of 73.7% and specificity of 94.9% in this cohort.

CONCLUSIONS

This study confirms the presence of NTRK fusions in Middle Eastern PTC which is significantly enriched in BRAF WT as well as pediatric age group and proposes the usefulness of IHC to screen for PTC patients with NTRK fusion that might benefit from TRK inhibitors.

PD-L1 Expression Is an Independent Marker for Lymph Node Metastasis in Middle Eastern Endometrial Cancer

Programmed death ligand 1 (PD-L1) expression in endometrial cancer (EC) tumor cells have been reported in several studies with inconsistent results. Furthermore, there is scarcity of data on the prevalence and prognostic significance of PD-L1 expression in EC from Middle Eastern ethnicity. We aimed to assess PD-L1 expression in a large cohort of Middle Eastern EC and to correlate this with clinico-pathological factors, as well as mismatch repair (MMR) protein status and patients’ outcome. PD-L1 expression was investigated using immunohistochemistry on tissue microarray in an unselected cohort of 440 EC. Kaplan–Meier and logistic regression analysis were used to compare the outcome and prognostic factors. PD-L1 expression in tumor tissue was detected in 18.9% (83/440) EC cases with no impact on survival. When stratified for MMR protein status, PD-L1 expression was similar for both MMR deficient and MMR proficient ECs. However, the expression of PD-L1 in tumor cells was significantly associated with type II (non-endometrioid) histology (p = 0.0005) and lymph node metastasis (p = 0.0172). Multivariate analysis showed PD-L1 expression to be an independent risk factor for lymph node metastasis (odds ratio: 2.94; 95% CI: 1.26–6.84; p = 0.0123). In conclusion, PD-L1 was strongly associated with non-endometrioid EC and was an independent prognostic marker of lymph node metastasis.

PD-L1 Is an Independent Prognostic Marker in Middle Eastern PTC and Its Expression Is Upregulated by BRAFV600E Mutation

Simple Summary

This study was conducted to investigate the prognostic significance of programmed death-ligand 1 (PD-L1) expression in a large cohort of Middle Eastern papillary thyroid carcinoma (PTC) patients and to explore the correlation of PD-L1 and BRAFV600E mutations in PTC tumors and cell lines. We found PD-L1 over-expression in PTC patients and it was significantly associated with aggressive clinico-pathological parameters and BRAF mutation. PTC patients with co-existing PD-L1 over-expression and BRAF mutation had a poor disease-free survival. In vitro studies showed that BRAF inhibition induces PD-L1 expression in BRAF-mutated PTC cell lines via mitogen-activated protein kinase kinase/extracellular-signal-regulated kinase (MEK/ERK) pathway activation. Silencing of PD-L1 in BRAF-mutated cell lines significantly attenuated cell growth. Our data suggest that PD-L1 could represent a useful prognostic marker for risk stratification in Middle Eastern PTC and that a programmed cell death protein 1 (PD-1)/PD-L1 inhibitor could be a potential therapeutic option for aggressive PTC cancers, such as the tall cell variant, BRAF mutation-positive patients that are unresponsive to standard PTC treatment.

Abstract

PD-L1 inhibition is a promising therapeutic target whose efficacy has been demonstrated in several cancers. Immunohistochemistry was performed to assess PD-L1 protein expression in PTC. We further conducted in vitro analysis to investigate the role of PD-L1 in regulating BRAFV600E in PTC cell lines. PD-L1 over-expression was noted in 32.4% (473/1458) of cases and significantly associated with aggressive clinico-pathological parameters. Importantly, PD-L1 was found to be an independent poorer prognostic marker. We also found PD-L1 to be significantly associated with BRAF mutation and patients with co-existing PD-L1 over-expression and BRAF mutation had a poor disease-free survival compared to patients with BRAF mutation alone. In vitro analysis showed high expression of PD-L1 in BRAF-mutated PTC cell lines compared to a BRAF wild-type cell line. Inhibition of BRAF using vemurafenib induced PD-L1 expression in BRAF-mutated cell lines without affecting cell growth. Knockdown of PD-L1 in BRAF-mutated cell lines significantly decreased the cell growth and induced apoptosis. Our data suggest that PD-L1 might represent a useful prognostic marker in Middle Eastern PTC and PD-L1 inhibition could be a potential therapeutic option for aggressive PTC cancers, such as the tall cell variant, BRAF mutation-positive patients that are unresponsive to standard treatment.

Prognostic Value and Function of KLF5 in Papillary Thyroid Cancer

Simple Summary

This study was conducted to investigate the clinical significance and prognostic value of KLF5 in a large cohort of Middle Eastern PTC patients and explore its functional role and mechanism in PTC cell lines in vitro and in vivo. We found KLF5 over-expression in PTC patient cases and this was significantly associated with aggressive clinico-pathological parameters and worse outcome. We also found a significant association between KLF5 and HIF-1α in PTC patients and cell lines. Functionally, KLF5 promoted cell growth, stemness, invasion, migration, and angiogenesis, while its inhibition reverses its action in PTC cell lines. Finally, the depletion of KLF5 regressed PTC tumor growth in nude mice. These data suggest that KLF5 may potentially be a suitable therapeutic target in PTC, and pharmacological inhibition of KLF5 might be a viable therapeutic option for the treatment of patients with an aggressive subtype of PTC.

Abstract

The Krüppel-like factor 5 (KLF5), a zinc-finger transcriptional factor, is highly expressed in several solid tumors, but its role in PTC remains unclear. We investigated the expression of KLF5 protein in a large cohort of PTC patient samples and explored its functional role and mechanism in PTC cell lines in vitro and in vivo. KLF5 overexpression was observed in 65.1% of all PTC cases and it was significantly associated with aggressive clinico-pathological parameters and poor outcome. Given the significant association between KLF5 and HIF-1α overexpression in PTC patients, we investigated the functional correlation between KLF5 and HIF-1α in PTC cells. Indeed, the analysis revealed the co-immunoprecipitation of KLF5 with HIF-1α in PTC cells. We also identified KLF5-binding sites in the HIF-1α promoter that specifically bound to KLF5 protein. Mechanistically, KLF5 promoted PTC cell growth, invasion, migration, and angiogenesis, while KLF5 downregulation via specific inhibitor or siRNA reverses its action in vitro. Importantly, the silencing of KLF5 decreases the self-renewal ability of spheroids generated from PTC cells. In addition, the depletion of KLF5 reduces PTC xenograft growth in vivo. These findings suggest KLF5 can be a possible new molecular therapeutic target for a subset of PTC.

Prognostic Significance of COX-2 Overexpression in BRAF-Mutated Middle Eastern Papillary Thyroid Carcinoma

The cyclooxygenase-2 (COX-2)–prostaglandin E2 (PGE2) pathway has been implicated in carcinogenesis, with BRAF mutation shown to promote PGE2 synthesis. This study was conducted to evaluate COX-2 expression in a large cohort of Middle Eastern papillary thyroid carcinoma (PTC), and further evaluate the prognostic significance of COX-2 expression in strata of BRAF mutation status. BRAF mutation analysis was performed using Sanger sequencing, and COX-2 expression was evaluated immunohistochemically using tissue microarray (TMA). COX-2 overexpression, noted in 43.2% (567/1314) of cases, was significantly associated with poor prognostic markers such as extra-thyroidal extension, lymph-node metastasis, and higher tumor stage. COX-2 was also an independent predictor of poor disease-free survival (DFS). Most notably, the association of COX-2 expression with DFS differed by BRAF mutation status. COX-2 overexpression was associated with poor DFS in BRAF-mutant but not BRAF wild-type PTCs, with a multivariate-adjusted hazard ratio of 2.10 (95% CI = 1.52–2.92; p < 0.0001) for COX-2 overexpressed tumors in BRAF-mutant PTC. In conclusion, the current study shows that COX-2 plays a key role in prognosis of PTC patients, especially in BRAF-mutated tumors. Our data suggest the potential therapeutic role of COX-2 inhibition in patients with BRAF-mutated PTC.

Krupple-Like Factor 5 is a Potential Therapeutic Target and Prognostic Marker in Epithelial Ovarian Cancer

Epithelial ovarian cancer (EOC) is the most lethal gynecological malignancy. Despite current therapeutic and surgical options, advanced EOC shows poor prognosis. Identifying novel molecular therapeutic targets is highly needed in the management of EOC. Krupple-like factor 5 (KLF5), a zinc-finger transcriptional factor, is highly expressed in a variety of cancer types. However, its role and expression in EOC is not fully illustrated. Immunohistochemical analysis was performed to assess KLF5 protein expression in 425 primary EOC samples using tissue microarray. We also addressed the function of KLF5 in EOC and its interaction with signal transducer and activator of transcription 3 (STAT3) signaling pathway. We found that KLF5 overexpressed in 53% (229/425) of EOC samples, and is associated with aggressive markers. Forced expression of KLF5 enhanced cell growth in low expressing EOC cell line, MDAH2774. Conversely, knockdown of KLF5 reduced cell growth, migration, invasion and progression of epithelial to mesenchymal transition in KLF5 expressing cell lines, OVISE and OVSAHO. Importantly, silencing of KLF5 decreased the self-renewal ability of spheroids generated from OVISE and OVSAHO cell lines. In addition, downregulation of KLF5 potentiated the effect of cisplatin to induce apoptosis in these cell lines. These data reveals the pro-tumorigenic role of KLF5 in EOC and uncover its role in activation of STAT3 signaling pathway, suggesting the importance of KLF5 as a potential therapeutic target for EOC therapy.

Annual Hazard Rate of Recurrence in Middle Eastern Papillary Thyroid Cancer over a Long-Term Follow-Up

Predicting the pattern of recurrence in papillary thyroid cancer (PTC) is necessary to establish optimal surveillance and treatment strategies. We analyzed changes in hazard rate (HR) for tumor recurrence over time in 1201 unselected Middle Eastern PTC patients. The changes in risk were further analyzed according to clinical variables predictive of early (≤5 years) and late (>5 years) recurrence using Cox regression analysis to identify patient populations that remain at risk. Tumor recurrence was noted in 18.4% (221/1201) patients. The annualized hazard of PTC recurrence was highest during the first 5 years (2.8%), peaking between 1 and 2 years (3.7%), with a second smaller peak between 13 and 14 years (3.2%). Patients receiving radioactive iodine (RAI) therapy had lower recurrence hazard compared to those who did not (1.5% vs. 2.7%, p = 0.0001). Importantly, this difference was significant even in intermediate-risk PTC patients (0.7% vs. 2.3%; p = 0.0001). Interestingly, patients aged ≥55 years and having lymph node metastasis were at persistent risk for late recurrence. In conclusion, we confirmed the validity of the double-peaked time-varying pattern for recurrence risk in Middle Eastern PTC patients and our findings could help in formulating individualized treatment and surveillance plans.

Clonal Evolution and Timing of Metastatic Colorectal Cancer

Colorectal cancer (CRC) is the third most frequently diagnosed cancer worldwide, where ~50% of patients develop metastasis, despite current improved management. Genomic characterisation of metastatic CRC, and elucidating the effects of therapy on the metastatic process, are essential to help guide precision medicine. Multi-region whole-exome sequencing was performed on 191 sampled tumour regions of patient-matched therapy-naïve and treated CRC primary tumours (n = 92 tumour regions) and metastases (n = 99 tumour regions), in 30 patients. Somatic variants were analysed to define the origin, composition, and timing of seeding in the metastatic progression of therapy-naïve and treated metastatic CRC. High concordance, with few genomic differences, was observed between primary CRC and metastases. Most cases supported a late dissemination model, via either monoclonal or polyclonal seeding. Polyclonal seeding appeared more common in therapy-naïve metastases than in treated metastases. Whereby, treatment prompted for the selection of distinct resistant clones, through monoclonal seeding to distant metastatic sites. Overall, this study reinforces the importance of early clinical detection and surgical excision of the CRC tumour, whilst further highlighting the clinical challenges for metastatic CRC with increased intratumour heterogeneity (either due to early dissemination or polyclonal metastatic spread) and the underlying risk of future therapeutic resistance in treated patients.

POLE and POLD1 pathogenic variants in the proofreading domain in papillary thyroid cancer

Thyroid cancer is the most frequent endocrine cancer with an increasing incidence rate worldwide and is the second most common malignancy among females in Saudi Arabia. Papillary thyroid cancer (PTC) is the most common subtype. Germline pathogenic variants in the proofreading domain of the POLE and POLD1 genes predispose to several types of cancers. However, the role of pathogenic variants of these two genes in PTC remains unknown. Capture sequencing, Sanger sequencing and immunohistochemistry were performed on 300 PTC cases from the Middle Eastern region. One germline pathogenic variant each of POLE (1/300, 0.33%) and POLD1 (1/300, 0.33%) genes was identified. Low expression of POLD1 was detected in 46.5% (133/286) of cases and was significantly associated with the follicular variant of PTC (P = 0.0006), distant metastasis (P = 0.0033) and stage IV tumours (P = 0.0081). However, no somatic pathogenic variant was detected in POLE gene. Furthermore, low expression of POLE was noted in 61.7% (175/284) of cases with no significant clinicopathological associations. Our study shows that pathogenic variant in the POLE and POLD1 proofreading domain is a cause of PTC and low expression of POLD1 is associated with poor prognostic markers in the Middle Eastern population. Further studies from different geographic populations are needed to determine the frequency and spectrum of proofreading domain pathogenic variants in POLE and POLD1 genes and in PTC from different ethnicities.

Abstract 2509: Genetic heterogeneity and evolutionary history of high grade ovarian carcinoma and matched distant metastases

BACKGROUND: High-grade serous ovarian carcinoma (HGSOC) is the most frequent type of ovarian carcinoma, associated with poor clinical outcome and metastatic disease. Although, metastatic processes are becoming more understandable, the genomic landscape and metastatic progression in HGSOC has not been elucidated.

METHODS: Multi-region whole-exome sequencing was performed on HGSOC primary tumors and their metastases (n=33 tumor regions) from 6 patients. The resulting somatic variants were analyzed to delineate tumor evolution and metastatic dissemination, and to compare the repertoire of events between primary HGSOC and metastasis.

RESULTS: All cases presented branching evolution patterns in primary HGSOC, with three cases further showing parallel evolution in which different mutations on separate branches of a phylogenetic tree converge on the same gene. Furthermore, linear metastatic progression was observed in 67% of cases with late dissemination in which the metastatic tumor mostly acquires the same mutational process active in primary tumor, and parallel metastatic progression, with early dissemination in the remaining 33.3% of cases. Metastatic specific SNVs were further confirmed as late dissemination events. We also found the involvement of metastatic-specific driver events in the Wnt/β-catenin pathway.

CONCLUSIONS: This study provides deeper insights into clonal evolution and mutational processes that can pave the way to new therapeutic targets.

Citation Format: Tariq Masoodi, Sarah Siraj, Abdul K. Siraj, Saud Azam, Zeeshan Qadri, Sandeep K. Parvathareddy, Fowzan S. Alkuraya, Khawla S. Al-Kuraya. Genetic heterogeneity and evolutionary history of high grade ovarian carcinoma and matched distant metastases [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 2509.

Abstract 3549: Low frequency of germline mutations in POLE and POLD1 proofreading domains in Middle Eastern colorectal cancers

Colorectal cancer (CRC) is one of the main causes of cancer related morbidity and mortality. Only ~ 5% of all CRCs occur as a result of mutations in well-defined CRC predisposing genes. The underlying causes in genetically unexplained CRC cases from Middle Eastern region are still unknown. We performed Capture sequencing and Sanger sequencing to screen the proofreading domains of DNA Polymerase Epsilon (POLE) and DNA Polymerase Delta 1 (POLD1) genes to find out the genetic causes in over 1100 CRC cases from Middle Eastern region. In our cohort, five mutations (0.44%) were identified in 1135 CRC cases, four in POLE gene (0.35%, 4/1135) and one (0.1%, 1/1135) in POLD1 gene. These mutations have been infrequently reported in Western populations. Furthermore, low expression of POLE was noted in 38.9% (417/1071) of cases and showed significant association with lymph node involvement (p=0.0184) and grade 3 tumors (p=0.0139). Whereas, low expression of POLD1 was observed in 51.9% (555/1069) of cases and was significantly associated with adenocarcinoma histology (p=0.0164), larger tumor size (T3 and T4 tumors; p=0.0012) and stage III tumors (p=0.0341). Our findings revealed that there was a low frequency of

mutations in POLE and POLD1 proofreading region in CRC cases and established that the mutations in the proofreading domain of these two genes were a rare cause of CRC in Middle Eastern region. It is feasible to screen multiple cancer related genes in CRC patients from Middle Eastern region using multigene panels including POLE and POLD1.

Citation Format: Rong Bu, Abdul K. Siraj, Kaleem Iqbal, Sandeep K. Parvathareddy, Tariq Masoodi, Nabil Siraj, Nabil Siraj, Maha Al-Rasheed, Sarah Siraj, Yan Kong, Saeeda O. Ahmed, Khadija A.S. Al-Obaisi, Ingrid G. Victoria, Khawla S. Al-Kuraya. Low frequency of germline mutations in POLE and POLD1 proofreading domains in Middle Eastern colorectal cancers [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 3549.

Abstract 3533: Germline POLE and POLD1 proofreading domain mutations in endometrial carcinoma from Middle Eastern region

Endometrial carcinoma (EC) accounts for 5.8% of all cancers in Saudi females. Although most ECs are sporadic, 2%-5% tend to be familial, being associated with Lynch syndrome and Cowden syndrome. In this study, we attempted to uncover the frequency, spectrum and phenotype of germline mutations in the proofreading domain of POLE and POLD1 genes in a large cohort of ECs from Middle Eastern region. We performed Capture sequencing and Sanger sequencing to screen for proofreading domains of POLE and POLD1 genes in 432 EC cases, followed by evaluation of protein expression using immunohistochemistry. Variant interpretation was performed using PolyPhen-2, MutationAssessor, SIFT, CADD and Mutation Taster. In our cohort, four mutations (0.93%) were identified in 432 EC cases, two each in POLE and POLD1 proofreading domains. Furthermore, low expression of POLE and POLD1 was noted in 41.1% (170/1414) and 59.9% (251/419) of cases, respectively. Both the cases harboring POLE mutation showed high nuclear expression of POLE protein, whereas, of the two POLD1 mutant cases, one case showed high expression and another case showed low expression of POLD1 protein. Our study shows that germline mutations in POLE and POLD1 proofreading region are a rare cause of EC in Middle Eastern population. However, it is still feasible to screen multiple cancer related genes in EC patients from Middle Eastern region using multigene panels including POLE and POLD1.

Keywords: POLE; POLD1; Endometrial carcinoma; Proof-reading domain mutations; Germline.

Citation Format: Abdul K. Siraj, Sandeep K. Parvathareddy, Rong Bu, Kaleem Iqbal, Sarah Siraj, Tariq Masoodi, Laila Ghazwani, Yan Kong, Maria A. Sabido, Wafaa Albalawy, Ingrid F. Victoria, Mary J. Galvez, Khawla S. Al-Kuraya. Germline POLE and POLD1 proofreading domain mutations in endometrial carcinoma from Middle Eastern region [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 3533.