Introduction:Circulating immune cells serve as readily accessible biomarkers in cancer patients. Some of them, such as neutrophils, lymphocytes as well as the neutrophil to lymphocyte ratio (NLR), have been validated as prognostic indicators of disease outcome whereas the significance of others remains controversial due to conflicting findings. Moreover, the interplay and correlation among these markers have not been thoroughly investigated nor has their dynamic course during chemotherapy. Methods:Blood was collected from 16 healthy donors and 90 patients receiving first line chemotherapy for metastatic colorectal cancer before, during and after chemotherapy. Neutrophils, lymphocytes, circulating CD4+CD25+FOXP3+ regulatory T lymphocytes (Tregs), monocytic myeloid derived suppressor cells (mMDSCs), polymorphonuclear myeloid derived suppressor cells (pMDSCs) and other exploratory myeloid subsets were immunophenotyped and quantified with flow cytometry. Their frequencies were compared between healthy donors and patients and correlated with each other and with clinical parameters. Associations with progression-free and overall survival were evaluated using Cox proportional hazards regression and longitudinal changes in immune cell populations during chemotherapy were analyzed using linear mixed-effects models. Results:Circulating Tregs were significantly reduced in patients with high neutrophil counts (7% vs 17%, p=0.04), increased significantly during treatment in responders, particularly in patients achieving complete or partial response (+16%, p = 0.003) but did not demonstrate prognostic significance. pMDSCs were further stratified by CD16 expression into a CD16+ subset associated with favorable outcome and a CD16dim/- subset enriched in patients demonstrating poor prognosis. Frequency of circulating mMDSCs was modestly increased in patients but retained adverse prognostic significance (HR 1.98, CI 1.04-3.78, p=0.039) and correlated with the CD16dim/- pMDSC fraction. Mature CD15+CD33- polymorphonuclear cells were significantly expanded in patients (79% vs 73%, p=0.003) and correlated with adverse clinical features, whereas lower levels correlated with improved survival (HR 0.54, CI 0.3-0.98, p=0.045). Rare HLA-DR+CD16+ granulocytic subset demonstrated significantly reduced levels in patients compared to healthy donors while their kinetics during treatment also correlated inversely with disease burden. Discussion:Circulating immune cell subsets in metastatic colorectal cancer exhibit considerable baseline heterogeneity and distinct immune kinetics during chemotherapy. Our findings demonstrate that conventional leukocyte populations, when evaluated individually, together with detailed immunophenotyping provide complementary prognostic information, revealing previously unappreciated heterogeneity within major immune cell populations and a network of novel interrelationships among circulating immune cells. Together, these observations support comprehensive immune profiling as a promising approach for future biomarker development and immune-based patient stratification.

The mechanisms of homologous recombination deficiency (HRD) in non-small cell lung cancer (NSCLC) remain understudied, mainly due to the low prevalence of germline or somatic mutations in relevant genes such as BRAC1/2 in this cancer type. However, recent reports suggest that an important subset of patients present high genomic scarring score (GSS), indicating HRD, although the causes are not always clear. In this work, we examined a cohort of 147 patients and sought to correlate GSS, mutational profile and relevant gene expression with response to PARP inhibition in preclinical functional experiments. We used next generation sequencing to evaluate the GSS of each primary tumor with a commercially available sequencing kit which also provides information on the genetic status of relevant HRR and other genes. We performed rt-PCR analyses to assess the expression of certain genes, and we established patient-derived xenografts to examine the response of high and low GSS (h-GSS and l-GSS respectively) tumors to PARP inhibition. 42 out of 147 tumors (28.6%) presented a GSS>50 (h-GSS). The prevalence of germline or somatic mutations in HRR genes was not significantly different between h-GSS and l-GSS tumors (18/42 vs 37/105, p=0.388). On the contrary, TP53 mutation frequency (p<0.001) as well as variant allele frequency (p<0.0001) correlated significantly with GSS. Expression of HRR genes was marginally higher in h-GSS tumors, whereas expression of the epigenetic factor KMT2C was significantly lower in that subset and presented an inverse correlation with both GSS (p=0.0059) and TP53 variant allele frequency (p=0.02). The growth of h-GSS PDXs was significantly hampered upon PARP inhibition. Our data show that for early-stage NSCLC, the GSS might be a valuable biomarker to stratify patients who might benefit from PARP inhibition. As this is not dependent on HRR genetic status in this cohort, further experimentation is needed to elucidate the complex relationship between TP53 status, KMT2C expression and HRD. Katerina Tsilingiri, Anna Chalari, Georgia Christopoulou, Alexandra Voutsina, Pantelis Constantoulakis, Konstantinos Potaris, Ioannis Vamvakaris, Dora Hatzidaki, Georgina Zachou, Giannis Vatsellas, Vassilis Georgoulias, Athanasios Kotsakis, Apostolos Klinakis. Homologous recombination deficiency in non-small cell lung cancer: genetic and epigenetic causes beyond HRR [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 2919.

To investigate the incidence and prognostically significant correlations and cooperations of LKB1 loss of expression in non-small cell lung cancer (NSCLC), surgical specimens from 188 metastatic and 60 non-metastatic operable stage I-IIIA NSCLC patients were analyzed to evaluate their expression of LKB1 and pAMPK proteins in relation to various processes. The investigated factors included antitumor immunity response regulators STING and PD-L1; pro-angiogenic, EMT and cell cycle targets, as well as metastasis-related (VEGFC, PDGFRα, PDGFRβ, p53, p16, Cyclin D1, ZEB1, CD24) targets; and cell adhesion (β-catenin) molecules. The protein expression levels were evaluated via immunohistochemistry; the RNA levels of LKB1 and NEDD9 were evaluated via PCR, while KRAS exon 2 and BRAFV600E mutations were evaluated by Sanger sequencing. Overall, loss of LKB1 protein expression was observed in 21% (51/248) patients and correlated significantly with histotype (p < 0.001), KRAS mutations (p < 0.001), KC status (concomitant KRAS mutation and p16 downregulation) (p < 0.001), STING loss (p < 0.001), and high CD24 expression (p < 0.001). STING loss also correlated significantly with loss of LKB1 expression in the metastatic setting both overall (p = 0.014) and in lung adenocarcinomas (LUACs) (p = 0.005). Additionally, LKB1 loss correlated significantly with a lack of or low β-catenin membranous expression exclusively in LUACs, both independently of the metastatic status (p = 0.019) and in the metastatic setting (p = 0.007). Patients with tumors yielding LKB1 loss and concomitant nonexistent or low β-catenin membrane expression experienced significantly inferior median overall survival of 20.50 vs. 52.99 months; p < 0.001 as well as significantly greater risk of death (HR: 3.32, 95% c.i.: 1.71–6.43; p <0.001). Our findings underscore the impact of the synergy of LKB1 with STING and β-catenin in NSCLC, in prognosis.

PARP inhibitors (PARPi) have shown efficacy in tumours harbouring mutations in homologous recombination repair (HRR) genes. Somatic HRR mutations have been described in patients with Non-Small Cell Lung Cancer (NSCLC), but PARP inhibitors (PARPi) are not yet a therapeutic option. Here we assessed the homologous recombination status of early-stage NSCLC and explored the therapeutic benefit of PARPi in preclinical models. The Genomic Scarring Score GSS (GSS) and HRR mutation profile of 136 patients were assessed. High GSS (h-GSS) was observed in 39 (28.7%) patients half of which carried pathogenic/likely pathogenic somatic HRR mutations. TP53 mutations were significantly enriched in h-GSS tumours (p < 0.001). Olaparib significantly delayed tumour growth in h-GSS but not l-GSS Patient-derived Xenografts (PDXs), while patients with h-GSS/TP53mut tumours respond favourably to adjuvant platinum-based chemotherapy. Our functional data clearly support the idea that the use of GSS rather than the mutational status of HRR genes could select patients for administration of PARPi.

subsequently validated, and a nomogram was employed to optimize its clinical applicability range.Results: Patients were divided into two genomic subtypes based on prognostic genes using an unsupervised clustering analysis to further investigate the special regulation mechanism.Kaplan-Meier curves demonstrated that patients in gene cluster A had significantly better overall survival (OS) times compared to those in gene cluster B. An eight-gene prognostic signature was developed using LASSO Cox regression analysis.Patients in the high-risk group exhibited a worse OS compared to those in the low-risk group (71.9 months vs. 118.5 months).Notably, patients in the high-risk group with micropapillary component had significantly worse OS compared to those in the intermediate-(HR¼1.81,95% CI 1.13-2.88,P¼0.013) and low-risk groups (HR¼1.03,95% CI 0.63-1.70,P¼0.910), whereas no significant difference was observed between patients without micropapillary component and the low-risk group.Conclusions: These findings are expected to provide fresh insight into the nature of this aggressive cancer subtype, pave a new path for assessing the disease prognosis, and assist in developing personalized therapeutic strategies for patients with LUAD.

Supplementary Figure 1A Supplementary Figure 1B Supplementary Figure 2A Supplementary Figure 2B

Colorectal cancer (CRC) remains a major public health issue. The detection of parameters that affect CRC prognosis is of great significance. KRAS mutations, play a crucial role in tumorigenesis with a strong predictive value. KRAS-mutated stage-IV CRC patients gain no benefit of the anti-EGFR therapy. The KRAS G12C mutation subtype is under investigation for treatment regimens. The present study aimed to detect various RAS mutations in a cohort of 578 RAS-mutated CRC patients; 49% of them had de novo metastatic disease; 60% were male; 71.4% had left-sided tumors; and 94.6% had a good performance status. KRAS mutations were detected in 93.2% of patients, with KRAS G12D being the most common subtype (30.1%). KRAS mutations presented shorter progression-free (PFS) and overall survival (OS), compared with NRAS mutations, although not significantly (PFS: 13.8 vs. 18.5 months; p = 0.552; OS: 53.1 vs. 60.9 months; p = 0.249). KRAS G12D mutations presented better OS rates (p = 0.04). KRAS G12C mutation, even though not significantly, presented worse PFS and OS rates. KRAS exon 3 and 4 mutations presented different PFS and OS rates, although these were not significant. Concluding, KRAS G12D and G12C mutations lead to better and worst prognosis, respectively. Further studies are warranted to validate such findings and their possible therapeutic implication.

Recent advances in sequencing technologies have allowed the in-depth molecular study of tumors, even at the single cell level. Sequencing efforts have uncovered a previously unappreciated heterogeneity among tumor cells, which has been postulated to be the driving force of tumor evolution and to facilitate recurrence, metastasis, and drug resistance. In the current study, focused on early-stage operable non-small cell lung cancer, we used tumor growth in patient-derived xenograft (PDX) models in mice as a fast-forward tumor evolution process to investigate the molecular characteristics of tumor cells that grow in mice, as well as the parameters that affect the grafting efficiency. We found that squamous cell carcinomas grafted significantly more efficiently compared with adenocarcinomas. Advanced stage, patient age and primary tumor size were positively correlated with grafting. Additionally, we isolated and characterized circulating tumor cells (CTC) from patients’ peripheral blood and found that the presence of CTCs expressing epithelial-to-mesenchymal (EMT) markers correlated with the grafting potential. Interestingly, exome sequencing of the PDX tumor identified genetic alterations in DNA repair and genome integrity genes that were under-represented in the human primary counterpart. In conclusion, through the generation of a PDX biobank of NSCLC, we identified the clinical and molecular properties of tumors that affected growth in mice.

While it is known that ScRad9 DNA damage checkpoint protein is recruited to damaged DNA by recognizing specific histone modifications, here we report a different way of Rad9 recruitment on chromatin under non DNA damaging conditions. We found Rad9 to bind directly with the copper-modulated transcriptional activator Mac1, suppressing both its DNA binding and transactivation functions. Rad9 was recruited to active Mac1-target promoters (CTR1, FRE1) and along CTR1 coding region following the association pattern of RNA polymerase (Pol) II. Hir1 histone chaperone also interacted directly with Rad9 and was partly required for its localization throughout CTR1 gene. Moreover, Mac1-dependent transcriptional initiation was necessary and sufficient for Rad9 recruitment to the heterologous ACT1 coding region. In addition to Rad9, Rad53 kinase also localized to CTR1 coding region in a Rad9-dependent manner. Our data provide an example of a yeast DNA-binding transcriptional activator that interacts directly with a DNA damage checkpoint protein in vivo and is functionally restrained by this protein, suggesting a new role for Rad9 in connecting factors of the transcription machinery with the DNA repair pathway under unchallenged conditions.

To gain insights on the transcriptional switches that modulate proper copper homeostasis in yeast, we have examined in detail functional interactions of the relevant transcriptional activator Mac1. We identified Hir1 transcriptional repressor and histone chaperone as a Mac1-interacting protein. This association directly recruits Hir1 on a Mac1 target, CTR1 promoter, quantitatively under induction conditions. We also found Hir1 interacting directly with a previously unknown partner, the Ssn6 (Cyc8) co-regulator. On the non-induced CTR1 promoter, a Hir1 transcriptional activation function was revealed, in the absence of Ssn6, which was dependent on the presence of Snf2 (Swi2) nucleosome remodeler. Moreover, Ssn6 was identified as a Mac1-dependent prominent repressor of CTR1 transcription, antagonizing Snf2 occupancy. Transcriptional induction by copper depletion was effected by the quantitative recruitment of Snf2 directed mainly by Mac1 and redundantly by the quantitatively accumulated Hir1 and Ssn6 pair. Our analysis showed that the activation-effecting chromatin remodeling of CTR1 was due to Snf2 and not to the Hir1 histone chaperone activity or ability to regulate histone levels and stoichiometry. Following initiation, Hir1 and Snf2, but not Ssn6, were found to associate also with the actively transcribing CTR1 coding region, where Hir1 followed the pattern of the elongating RNA polymerase II. Therefore, we have shown that, at the CTR1 gene, in association with Mac1 DNA-binding transcriptional activator, the distinct and alternate genetic and physical collaboration of three global regulators modulates the transcriptional state of a switch involved in copper homeostasis.

In a prospective single-arm trial, 73 patients with metastatic colorectal cancer received the FOLFIRI (leucovorin, 5-fluorouracil, irinotecan, oxaliplatin) regimen combined with the antiangiogenic agent aflibercept every 2 weeks. The aflibercept regimen was active, although not superior to current standards, with an objective response rate of 46.6%, median survival of 20.9 months, median progression-free survival of 8.4 months, and 12-month progression-free rate of 21.9%. Background: The efficacy and safety of the FOLFIRI (leucovorin, 5-fluorouracil, irinotecan, and oxaliplatin) regimen combined with aflibercept has not been studied in the first-line management of patients with metastatic colorectal cancer (mCRC). Patients and methods: In the context of a prospective single-arm trial (NCT02129257), patients with mCRC received standard doses of a maximum of 12 cycles of FOLFIRI combined with aflibercept (4 mg/kg body weight delivered intravenously) every 2 weeks, followed by aflibercept maintenance. Endpoints were 12-month progression-free survival rate, efficacy, and toxicity. Results: Seventy-three fit patients were enrolled onto the study between 2014 and 2016. Median relative dose intensities administered were 0.80 for irinotecan and 1.0 for aflibercept. The most common grade 3/4 adverse events were neutropenia (13 patients, 18%), febrile neutropenia (3 patients, 4%), diarrhea (11 patients, 15%), hypertension (19 patients, 26%), proteinuria (8 patients, 11%), infections (8 patients, 11%), and mucositis (6 patients, 8%), with no toxic deaths. The objective response rate was 46.6%, significantly associated with the presence of right-sided primary, synchronous metastases, and a relapse-free interval of < 12 months (odds ratio = 3.00, 2.92, and 3.75 respectively, P <= .05). Intermediate infiltration by stromal core lymphocytes correlated with progression-free survival (hazard ratio = 0.40, [95% confidence interval (CI), 0.19-0.83], P = .014). At a median follow-up of 24.5 months, 12-month progression-free survival rate was 21.9% (median overall survival 20.9 months [95% CI, 16.6-29], median progression-free survival 8.4 months [95% CI, 7.4-9.3]). Conclusion: The FOLFIRI + aflibercept regimen is active and tolerable; however, it failed to improve historical benchmarks of efficacy in chemonaive patients with mCRC. Preliminary data hint that this regimen has cytoreductive activity in disease with adverse biology. (C) 2018 Elsevier Inc. All rights reserved.

Abstract Introduction: Liquid biopsy provides real-time monitoring of tumor evolution and response to therapy through analysis of CTCs and plasma-ctDNA. ESR1 epigenetic silencing potentially affects response to endocrine treatment. We evaluated ESR1 methylation in CTCs and paired plasma-ctDNA. We evaluated ESR1 methylation in CTCs and paired plasma-ctDNA as a potential biomarker for response to everolimus/exemestane treatment. Materials and methods: A highly sensitive and specific real-time MSP assay for ESR1 methylation was developed and validated in: a) 65 primary breast tumors (FFPEs), b) EpCAM+ CTC-fractions (122 patients and 30 healthy donors; HD), c) plasma-ctDNA (108 patients and 30HD), d) in CTCs (CellSearch®) and in paired plasma-ctDNA for 58 BrCa patients. ESR1 methylation status was investigated in CTCs isolated from serial peripheral blood samples of 19 patients with ER+/ HER2- advanced BrCa receiving everolimus/exemestane. Results: ESR1 methylation was detected in: a) 25/65(38.5%) FFPEs, b) EpCAM+ CTC-fractions: 26/112(23.3%) patients and 1/30(3.3%) HD, c) plasma-ctDNA: 8/108(7.4%) patients and 1/30(3.3%) HD. ESR1 methylation was highly concordant in 58 paired DNA samples, isolated from CTCs (CellSearch®) and corresponding plasma. In serial peripheral blood samples of patients treated with everolimus/exemestane, ESR1 methylation was observed in 10/36(27.8%) CTC-positive samples, and was associated with lack of response to treatment (p=0.023 Fisher's Exact Test). Conclusions: We report for the first time the detection of ESR1 methylation in CTCs and a high concordance with paired plasma-ctDNA. ESR1 methylation in CTCs was associated with lack of response to everolimus/exemestane regimen. ESR1 methylation should be further evaluated as a potential liquid biopsy-based biomarker. Citation Format: Sofia Mastoraki, Areti Strati, Eleni Tzanikou, Maria Chimonidou, Eleni Politaki, Alexandra Voutsina, Amanda Psyrri, Vassilis Georgoulias, Evi S. Lianidou. ESR1 methylation: A liquid biopsy-based epigenetic assay for the follow up of patients with metastatic breast cancer receiving endocrine treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4577.

Background Toll-like receptors (TLRs) play essential role in innate and acquired immunity, are expressed in various cell types, and are associated with altered susceptibility to many diseases, and cancers. The aim of this study was to investigate TLR2 (-196 to-174del), TLR4 (Asp299Gly and Thr399Ile) and TLR9 (T1237C and T1486C) gene polymorphisms at risk of colorectal cancer (CRC) development and progression. Methods Peripheral blood was obtained from 397 patients with adjuvant (stage II/III, n = 202) and metastatic (n = 195) CRC. Moreover, blood samples from 50 healthy volunteers and 40 patients with adenomatous polyps were also included as control groups. DNA from patients and controls was analyzed using PCR and PCR-RFLP for genotyping functional polymorphism within TLR2, TLR4 and TLR9 genotypes. Results TLR2 - 196 to-174del/del genotype was detected in 76.6% of the patients and was significantly higher that the controls groups (p<0.001). TLR4 Asp299Gly, TLR4 Thr399Ile, TLR9 T1237C and T1486C homozygous genotypes were detected in 70.5%, 70.5%, 61.5% and 61.5% of the patients respectively, and were also significantly higher than that in the control groups (p<0.001). All polymorphisms detected were also significantly associated with the metastatic disease (p<0.001) leading to shorter overall survival (p<0.001); whereas, TLR4 Asp299Gly and Thr399Ile polymorphisms were significantly associated with KRAS mutations. Conclusions The detection of higher frequencies of the TLR2, TLR4 and/or TLR9 polymorphisms in CRC patients compared with the control groups highlight the role of these polymorphism in CRC development and cancer progression.

e15053 Background:The role of combination chemotherapy plus anti-EGFR treatment in older patients with metastatic colorectal cancer (mCRC) is unclear. We conducted an open label phase II trial in order to evaluate the safety and efficacy of modified FOLFIRI plus panitumumab as first-line treatment in elderly patients with RAS wild-type mCRC. Methods: Patients ≥70 years old with unresectable all-RAS wild-type mCRC were treated with Panitumumab 6mg/kg as 60min iv infusion followed by Irinotecan 130mg/m2 as 90min iv infusion, Leucovorin 400mg/m2 as 2h iv infusion and 5-Fluorouracil 400mg/m2 as bolus iv infusion on day 1 and 5-Fluorouracil 1.200 mg/m2 as continuous iv infusion for 46h, every 2 weeks. Sample size calculation was based on the minimax Simon two-step design: The null hypothesis was that the overall response rate (ORR) is ≤ 30% versus the alternative hypothesis of ORR ≥ 50% (α = 0.05, power 80%). Results: Forty-six patients were enrolled in the study. Two patients did not receive treatment because they were RAS mutant. Median age for the 44 treated patients was 76 years (range 70-88). Males were 32 and the PS was 0, 1 and 2 in 25%, 70.5% and 4.5% of patients, respectively. Rectal cancer accounted for 25% while 15.9% of patients had the primary tumour in situ. Twenty-one partial responses were observed for an ORR of 47.7% (95%CI: 32.9%-62.5%) while seven patients (15.9%) had stable disease. After a median follow-up of 36.0 months, the median progression-free survival was 6.1 months (95%CI: 3.6-8.7) and the median overall survival was 20.9 months (95%CI: 11.7-30.1). Grade 3-4 neutropenia was recorded in 4 (9%) and grade 3-4 diarrhea in 9 (20.4%) patients while one patient had a grade 4 bowel perforation. One patient experienced grade 3 mucositis, two patients grade 3 skin toxicity and two patients grade 3 fatigue. There were no toxic deaths while one patient died due to bowel obstruction and one due to postoperative complications after removal of the primary tumor. Conclusions: The modified FOLFIRI plus panitumumab combination presented significant efficacy with manageable toxicity in elderly patients with mCRC.

INTRODUCTION:The presence of KRAS mutations in patients with metastatic colorectal cancer (mCRC) predicts poor response to agents targeting the EGFR. Even in patients with RAS wild type (WT) tumors, resistance eventually develops due to multiple mechanisms, including the expansion of previously undetected KRAS mutated clones. In this feasibility study, we aimed to detect KRAS exon 2 mutations in serial samples of circulating tumor cells (CTCs) of RAS WT patients with mCRC captured by the Isolation by Size of Epithelial Tumor cells (ISET) system.METHODS:CTC isolation using the ISET system was performed from prospectively collected blood samples obtained from patients with RAS and BRAF WT mCRC prior to first-line therapy initiation, at first imaging assessment and on disease progression. CTCs were enumerated using hematoxylin & eosin and CD45 double stain on a single membrane spot. DNA was extracted from 5 spots and KRAS exon 2 mutations were detected using a custom quantitative Polymerase Chain Reaction (qPCR) assay.RESULTS:Fifteen patients were enrolled and 28 blood samples were analyzed. In 9 (60%) patients, at least one sample was positive for the presence of a KRAS exon 2 mutation. In 11 out of 28 samples (39.2%) with detectable CTCs a KRAS mutation was detected; the corresponding percentages for baseline and on progression samples were 27% and 37.5%, respectively. The most commonly detected mutations were G13D and G12C (n=3). The presence of KRAS mutated CTCs at baseline was not prognostic for either PFS (P=.950) or OS (P=.383). CTC kinetics did not follow tumor response patterns.CONCLUSION:The results demonstrate that using a qPCR-based assay, KRAS exon 2 mutations could be detected in CTCs captured by the ISET system from patients with RAS WT primary tumors. However, the clinical relevance of these CTCs remains to be determined in future studies.