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Traditional tissue-based assessments of genomic alterations in castration-resistant prostate cancer (CRPC) can be challenging. To evaluate the real-world clinical utility of liquid biopsies for the evaluation of genomic alterations in CRPC, we preemptively collected available plasma samples and archival tissue samples from patients that were being treated for clinically confirmed CRPC. The cell-free DNA (cfDNA) and tumor tissue DNA were analyzed using the AlphaLiquid®100-HRR panel. Plasma samples from a total of 87 patients were included in this study. Somatic mutations from cfDNA were detected in 78 (89.7%) patients, regardless of the presence of overt metastasis or concomitant treatment given at the time of plasma sample collection. Twenty-three patients were found to have known deleterious somatic or germline mutations in HRR genes from their cfDNA. Archival tissue samples from 33 (37.9%) patients were available for comparative analysis. Tissue sequencing was able to yield an NGS result in only 51.5% of the tissue samples. The general sensitivity of cfDNA for detecting somatic mutations in tissues was 71.8%, but important somatic/germline mutations in HRR genes were found to have a higher concordance (100%). Liquid biopsies can be a reasonable substitute for tissue biopsies in CRPC patients when evaluating genomic alterations.

BACKGROUND: Circulating tumour DNA (ctDNA) has been spotlighted as an attractive biomarker because of its easy accessibility and real-time representation of tumour genetic profile. However, the clinical utility of longitudinal ctDNA monitoring has not been clearly defined. METHODS: Serial blood samples were obtained from metastatic colorectal cancer patients undergoing first-line chemotherapy. ctDNA was sequenced using a targeted next-generation sequencing platform which included 106 genes. Changes in ctDNA profile and treatment outcome were comprehensively analysed. RESULTS: A total of 272 samples from 62 patients were analysed. In all, 90.3% of patients had detectable ctDNA mutation before treatment. ctDNA clearance after chemotherapy was associated with longer progression-free survival which was independent of radiological response (adjusted hazard ratio 0.22, 95% confidence interval 0.10–0.46). Longitudinal monitoring was able to detect ctDNA progression which preceded radiological progressive disease (PD) in 58.1% (median 3.3 months). Diverse resistant mutations (34.9%) and gene amplification (7.0%) at the time of PD were discovered. For 16.3% of the PD patients, the newly identified mutations could be potential candidates of targeted therapy or clinical trial. CONCLUSION: ctDNA profile provided a more accurate landscape of tumour and dynamic changes compared to radiological evaluation. Longitudinal ctDNA monitoring may improve personalised treatment decision-making.

Background:Assessment of genomic alterations in castration-resistant prostate cancer (CRPC) patients has become an important process for treatment decisions, but traditional tissue-based evaluation can be challenging. Methods:To evaluate the clinical utility of liquid biopsy for the evaluation of genomic alterations in CRPC, we have prospectively collected plasma samples from patients being treated for clinically confirmed CRPC. The cell-free DNA (cfDNA) extracted from the plasma samples were analyzed using AlphaLiquid®100-HRR panel. Available archival tumor tissue samples were also collected and analyzed using the same panel. Results:Plasma samples from a total of 87 patients were included in this study. Somatic mutations from cfDNA were detected in 78 (89.7%) of all 87 CRPC patients. Somatic mutations were detectable regardless of the presence of overt metastasis, or concomitant treatment given at the time of plasma sample collection. 23 patients were found to have known deleterious mutations in HRR genes from their cfDNA. 11 patients were additionally found to have possibly pathogenic mutations calculated by pathogenicity prediction algorithm. Archival tissue samples were available in 33 (37.9%) of the patients, 31 from prostate and 2 from metastatic bone lesions, collected a median of 2 years before the blood sample collection. Tissue sequencing was able to yield an NGS result in only 51.5% of the tissue samples. The general sensitivity of cfDNA for detecting somatic mutations discovered from tissues was 71.8%, but important somatic/germline mutations in HRR genes were found in higher concordance (100%). Conclusions:Liquid biopsy can be a reasonable substitute for tissue biopsy in CRPC patients for evaluating genomic alterations.

Circulating tumor DNA (ctDNA) may reveal dynamic tumor status during therapy. We conducted serial ctDNA analysis to investigate potential association with clinical outcome in metastatic colorectal cancer (mCRC) patients receiving chemotherapy. Tissue KRAS/NRAS wild-type mCRC patients were enrolled and treated with first-line cetuximab-containing chemotherapy. ctDNA isolated from plasma were analyzed by next generation sequencing (NGS) with 16 targeted gene panel. Among 93 patients, 84 (90.3%) had at least 1 somatic mutation in baseline ctDNA samples (average 2.74). Five patients with KRAS or NRAS hotspot mutation in the ctDNA showed significantly worse progression-free survival (PFS) (p = 0.029). Changes in average variant allele frequency (VAF) in ctDNA showed significant correlation with tumor size change at the time of first response evaluation (p = 0.020) and progressive disease (PD) (p = 0.042). Patients whose average VAF decreased below cutoff (p p = 0.018). At the time of PD, 54 new mutations including KRAS and MAP2K1 emerged in ctDNA. ctDNA sequencing can provide mutation profile that could better reflect tumor mutation status and predict treatment outcome.

Tumor heterogeneity is one of the ongoing huddles in the field of colon cancer therapy. It is evident that there are countless clones which exhibit different phenotypes and therefore, single cell analysis is inevitable. Cancer stem cells (CSCs) are rare cell population within tumor which is known to function in cancer metastasis and recurrence. Although there have been trials to prove intra-tumoral heterogeneity using single cell sequencing, that of CSCs has not been clearly elucidated. Here, we articulate the presence of heterogeneous subclones within CD133 positive cancer stem cells through single cell sequencing. As a proof of principle, we performed phenotype-based high-throughput laser isolation and single cell sequencing (PHLI-seq) of CD133 positive cells in a frozen tumor tissue obtained from a patient with colorectal cancer. The result proved that CD133 positive cells were shown to be heterogeneous both in copy number and mutational profiles. Single cancer stem cell specific mutations such as RNF144A, PAK2, PARP4, ADAM21, HYDIN, KRT38 and CELSR1 could be also detected in liver metastatic tumor of the same patient. Collectively, these data suggest that single cell analysis used to spot subclones with genetic variation within rare population, will lead to new strategies to tackle colon cancer metastasis.

Background: Recently, anti-PD-L1 in combination with cytotoxic chemotherapy has shown significant survival benefit in a randomized phase 3 trial for unresectable or metastatic biliary tract cancer (BTC). However, no biomarker including PD-L1 expression has been established to predict clinical outcomes, and there is an unmet need for a novel predictive biomarker for anti-PD-1 or PD-L1 therapy. Here, we assessed TILs using artificial intelligence (AI)-powered spatial analysis in advanced BTC treated with anti-PD-1 beyond 1st line treatment. Methods: An AI-powered whole-slide image (WSI) analyzer (Lunit SCOPE IO, Lunit, Seoul, Korea) was used to segment tumor epithelium and stroma, and identification of intratumor TIL (iTIL) and stromal TIL (sTIL). H&E stained WSI from pre-treatment samples was acquired from Asan Medical Center (n =166), and a total of 154 samples (92.8%) after quality control were used for the final analysis. Immune phenotypes (IP) were defined as follow: inflamed as high iTIL and sTIL; immune-excluded as low iTIL and high sTIL; immune-desert as low TIL overall. Among them, 20 patients were available for multi-color flow cytometry analysis (FACS) using peripheral blood mononuclear cells, collected at baseline, C1D8, and C2D1. Results: All patients (n=154) were treated with anti-PD-1 (pembrolizumab or nivolumab) monotherapy, and 72 of 154 patients (46.8%) were treated as 2nd line. Gemcitabine plus cisplatin (GemCis) was used prior to anti-PD-1 as first-line therapy in all patients. Overall, 15 (9.7%) patients showed inflamed IP. With median follow-up duration of 15.4 months, the inflamed IP group showed better overall survival (17.2 vs. 6.6 months, P=0.03), and progression-free survival (PFS; 4.5 vs. 2.6 months, P=0.09) along with higher PFS rate at 12 months (33.3% vs. 11.5%, P=0.035), and overall response rate (26. 7% vs. 8.6%, P=0.053) than other phenotype groups. There was no significant difference in median PFS with GemCis among IP groups (P=0.74). In the FACS available subgroup, inflamed IP showed higher baseline central memory T (Tcm)+effector memory T (Tem)/Tnaive ratio than other IPs. With the administration of anti-PD-1, Tcm+Tem/Tnaive ratio was increased, while the proportion of PD1+CD8+T, CD39+CD8+T, CD103+CD8+T and Treg were decreased in the inflamed IP group than other phenotype groups. Conclusions: Immune phenotypes classified by AI-powered spatial TIL analysis was effective to predict the clinical outcomes of patients with advanced BTC treated with anti-PD-1 therapy. Citation Format: Yeong Hak Bang, Kyunghye Bang, Jin Ho Shin, Hyunseok Yoon, Kyu-Pyo Kim, Inkeun Park, Jae Ho Jeong, Heung-Moon Chang, Baek-Yeol Ryoo, Chiyoon Oum, Seulki Kim, Yoojoo Lim, Gahee Park, Chan-Young Ock, Changhoon Yoo. Spatial analysis of tumor-infiltrating lymphocytes in tumor microenvironment as biomarker for immune checkpoint inhibition in biliary tract cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4333.

433 Background: Serial circulating tumor DNA (ctDNA) analysis enables us to detect minimal residual disease, to estimate recurrence and to trace evolution of cancer. However, the role of ctDNA in patients with advanced gastric cancer (AGC) who received palliative chemotherapy is still unclear. We performed this study to evaluate if serial ctDNA can predict clinical outcomes of chemotherapy and propose evolutionary findings during chemotherapy. Methods: The patients with histopathologically confirmed AGC and who received palliative chemotherapy were enrolled. Serial blood sample for ctDNA sequencing were obtained at baseline (BL) (before first-line chemotherapy), after first cycle and every 2-3 months until disease progression. ctDNA sequencing was performed for all samples using the next-generation sequencing (NGS) platform with a targeted gene panel including 106 genes. Single nucleotide variants (SNVs), insertions and deletions (Indels), and copy number variants (CNVs) were identified by ctDNA sequencing while serial ctDNA were monitored by tracing changes in the variants. ctDNA clearance was defined as no detection of any kind of variants or variant allele frequency (VAF) less than 0.1%. Results: A total of 50 patients were registered and 248 samples were collected. Median age was 62. HER2-positive GC were 5 (10.0%) and 49 received fluoropyrimidine plus platinum (1 did not receive chemotherapy). Response rate and median progression-free survival (PFS) were 42.9% and 10.7 months (95% CI, 7.9-13.6). Among 40 who were available for BL ctDNA, patients who were detected with ctDNA variant (D group) were 21 (52.5%). TP53 mutation was the most frequently observed genetic alteration in BL ctDNA (76.2%) and median copy numbers of ERBB2 in HER2-positive GC were 28 (range 2-42). D group were more frequently observed in tubular or papillary adenocarcinoma than in poorly cohesive carcinoma (69.0% vs. 9.1%, p = 0.001). Patients who were not detected with any kind of ctDNA variant (ND group) showed a trend in longer PFS, compared to D group, however it was not significant (10.5 vs 7.9 months, p = 0.29). In serial analysis during first-line chemotherapy, ctDNA clearance was observed in 14 (70.0%) out of 20 in D group. Patients with ctDNA clearance showed significantly longer PFS, compared with patients without ctDNA clearance (9.8 vs. 3.6 months, p < 0.001). Among 32 patients who had disease progression, increased VAF or re-development of previous BL ctDNA variants were observed in 16 (50.0%). Increased VAF or re-development of BL ctDNA were detected in 2.1 months earlier than clinical or radiologic deterioration. Conclusions: Serial ctDNA could predict clinical outcomes of chemotherapy and detect disease progression earlier than clinical or radiological findings in AGC. Further study for serial ctDNA is needed to find out the resistant mechanism and evolutionary process in cancer.

Among prospectively enrolled adult patients with cancer receiving immune checkpoint inhibitors (ICIs; n = 46) or cytotoxic agents (n = 90), seroprotection and seroconversion rates after seasonal quadrivalent influenza vaccinations were higher with ICI than with cytotoxic chemotherapy. These results support annual influenza vaccinations for cancer patients receiving ICIs. Clinical Trials Registration clinicaltrials.gov (NCT03590808).

Introduction: Regorafenib is a multikinase inhibitor which showed clinical benefit in patients with treatment refractory metastatic colorectal cancer. However, as only a subset of patients derives clinical benefit from regorafenib, it is essential to identify biomarker to predict therapeutic response. Circulating tumor DNA (ctDNA) is emerging as a valuable non-invasive tool to identify tumor heterogeneity and tumor burden. This study investigated ctDNA dynamics in patients with metastatic colorectal cancer treated with regorafenib. Methods: This is a prospective biomarker study including patients with refractory metastatic colorectal cancer treated with regorafenib (ClinicalTrial.gov Identifier: NCT01996969). Patients with metastatic colorectal cancer who were refractory to standard therapies (fluoropyrimidine, oxaliplatin, and irinotecan) were eligible for the current study. Patients received oral regorafenib 160 mg once daily for the first 3 weeks of each 4-week cycle and were treated until disease progression, death, unacceptable toxicity, or decision by the treating physicians. Blood samples were obtained prior to regorafenib treatment and after every two cycles of regorafenib treatment until disease progression. ctDNA was detected by AlphaLiquid® 100 target capture panel (IMBdx, Inc., Seoul, South Korea). Alphaliquid® 100 is a tumor agnostic panel consist of 106 genes, including 10 gene fusion and MSI. Variant allele frequency (VAF) amount was calculated by adding the VAF value of all altered genes. Results: A total of 110 patients were included in the present study. Baseline blood samples were successfully acquired in 107 patients (97.3%) with a total of 713 genetic alteration. Mutation was most frequently found in TP53 (76.6%) followed by APC (75.7%), KRAS (43.0%), PIK3CA (17.8%), and SMAD4 (17.8%). BRAF mutation was found in 8.4% of patients and NRAS was detected in 3.7% of patients. Blood samples after two cycle of regorafenib was acquired in 106 patients, and was acquired in 95 patients after disease progression. Among 104 patients with baseline and follow-up cfDNA, the mean VAF at baseline was 12.8% and 7.2% in follow-up. This resulted in a mean VAF change of -5.61% (absolute value) and -43.7% (relative change). VAF decreased markedly after 2 cycles of regorafenib in several genes, including CSF1R, JAK3, KIT, ROS1, and TERT. Although, VAF change of specific gene was not associated with regorafenib outcome, VAF change of whole gene was an early predictive marker for regorafenib. Reduction in VAF amount of ≥ 50% after two cycles of regorafenib were associated with a significantly improved PFS (6.1 vs. 2.7 months, p = 0.002), OS (11.3 vs. 5.9 months, p = 0.001), and higher disease control rate (86.3% vs. 51.1%, p < 0.001). Conclusions: Serial ctDNA could be used as an early predictive biomarker in metastatic colorectal cancer treated with regorafenib. Citation Format: Dae-Won Lee, Sae-Won Han, Yoojoo Lim, Hwang-Phill Kim, Hanseong Roh, Min Jung Kim, Seung-Bum Ryoo, Ji Won Park, Seung-Yong Jeong, Kyu Joo Park, Gyeong Hoon Kang, Tae-You Kim. ctDNA change predicts treatment outcome of regorafenib in metastatic 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 5157.

Introduction: The fragment size of cfDNA derived from tumor cells are known to be shorter than that from normal cells for not yet precisely known mechanisms. We hypothesized that the fragment size of cfDNA can be utilized to reliably estimate tumor burden in patients with mCRC undergoing palliative chemotherapy. Methods: cfDNA sequencing data from mCRC patients receiving first-line palliative chemotherapy at Seoul National University Hospital (Seoul, Korea) were used for this analysis. The patients were enrolled in a main study evaluating the dynamic changes of circulating tumor DNA mutational profiles during chemotherapy. Blood samples were obtained prior to chemotherapy and after every four cycles of chemotherapy until disease progression. cfDNA sequencing data from normal individuals were used as control data. cfDNA sequencing for both cancer patients and normal individuals were performed using AlphaLiquid® 100 target capture panel (IMBdx, Inc., Seoul, South Korea). AlphaLiquid® 100 is a tumor agnostic panel consist of 106 genes, including 10 gene fusion and MSI. Based on the panel sequencing data, the genetic alterations and the fragment size of cfDNA were calculated. The fragmentation ratio was defined by the ratio of the read fragment proportion in size range P1 (100 - 155 bp) and P2 (160 - 180 bp). Results: cfDNA sequencing data from 280 plasma samples from 62 mCRC patients and 50 healthy controls were used for analysis. Compared to cfDNA from healthy controls, the cfDNA fragment sizes from mCRC patients were significantly shorter (169.585 bp vs. 173.964 bp; p < 0.001). Comparing the fragment sizes by the mutational status, the fragment sizes of alleles with detected somatic mutations were significantly shorter than those with reference alleles (mean fragment size 155.853 bp in alleles with somatic mutations vs. 160.613 bp in reference alleles; p < 0.001), but such difference was not observed with germline mutations (mean fragment size 160.911 bp in alleles with germline mutations vs. 159.889 bp in reference alleles; p = 0.992). Further, the clonality inferred from the variant allele frequency (VAF) of somatic mutation was negatively correlated with the size of the cfDNA fragment. The read fragment proportion in size range P1 was significantly associated with the clonality (r = 0.86, p Conclusions: The fragmentation ratio calculated from cfDNA in mCRC patients can represent tumor burden in dynamic samples and potentially can be used as a biomarker. Citation Format: Jun-Kyu Kang, Hwang-Phill Kim, Yoojoo Lim, Su Yeon Kim, Tae-You Kim. cell-free DNA (cfDNA) fragment size as a potential quantitative biomarker for metastatic colorectal cancer (mCRC) [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 5164.

2621 Background: The IIP, defined by enriched intratumoral tumor-infiltrating lymphocytes (TIL), is a potential tumor-agnostic biomarker of responsiveness to ICI therapy. Here, we validate the IIP, as assessed by Lunit SCOPE IO, an AI-powered spatial TIL analyzer that runs on routine H&E-stained whole-slide images (WSI), for clinical outcome prediction in a large, multi-center international cohort of ICI-treated patients, demonstrating its utility as a practical biomarker to guide ICI treatment planning. Methods: Lunit SCOPE IO was developed using 17,849 H&E WSI of multiple cancer types, annotated by 104 board-certified pathologists (13.5 x 109 µm2 area and 6.2 x 106 TIL). IIP+ tumors were defined as those with ≥ 20% of all 1 mm2 tumor tiles in a WSI classified as having a high intratumoral TIL density. We evaluated the correlation between IIP and ICI treatment outcomes (overall response rate (ORR) and progression-free survival (PFS), assessed by RECIST v1.1) in a real-world dataset of 1,806 patients ( > 16 primary tumor types) retrospectively collected from Stanford University Medical Center, Samsung Medical Center, Chonnam National University Hospital, Seoul National University Bundang Hospital, and Northwestern University. IIP status was sub-analyzed by PD-L1 22C3 tumor proportion score (TPS, n = 798), microsatellite status, and tumor mutational burden (TMB, n = 130). Results: The IIP+ phenotype (35.2%, 636 of 1,806) was highly enriched in nasopharyngeal carcinoma (68.0%), melanoma (56.3%), renal cell carcinoma (52.9%), and non-small cell lung cancer (NSCLC, 33.7%). The IIP+ proportion by PD-L1 TPS ( < 1% / ≥ 1%) was 21.6% and 40.7%, respectively. While 33.3% of microsatellite unstable (MSI-H) or TMB-high (≥ 10/Mb) tumors were IIP+, a substantial proportion (26.1%) of microsatellite stable (MSS), TMB-low tumors were IIP+. The ORR in IIP+ patients was significantly higher (26.0% vs. 15.8% in IIP-, p < 0.001). Median PFS for IIP+ was 5.3 months (95% CI 4.6-6.9 m), significantly longer than that for IIP- (3.1 m, 95% CI 2.8-3.6 m), with a hazard ratio (HR) of 0.68 (95% CI 0.61-0.76, p < 0.001). The association held after excluding NSCLC patients (n = 909) (HR 0.69, 95% CI 0.59-0.81, p < 0.001). On subgroup analysis, IIP+ correlated significantly with prolonged PFS, regardless of ICI regimen (mono / combo therapy) or PD-L1 TPS ( < 1% / ≥ 1%). Of note, IIP+ was predictive of favorable PFS only in the MSS, TMB-low group (n = 88, HR 0.56, 95% CI 0.33-0.96), but not in the MSI-H or TMB-high groups. Conclusions: The IIP, as evaluated by Lunit SCOPE IO, may represent a practical, clinically-actionable biomarker predictive of favorable ICI treatment outcomes across diverse cancer patient populations, including those with PD-L1 negative, MSS/TMB-low tumors, in whom predictive biomarkers are urgently needed.

595 Background: Stromal TIL are a well-recognized prognostic and predictive biomarker in breast cancer. There is a need for tools assisting visual assessment of TIL, to improve reproducibility as well as for convenience. This study aims to assess the clinical significance of AI-powered spatial TIL analysis in the prediction of pathologic complete response (pCR) after NAC in TNBC patients. Methods: H&E stained slides and clinical outcomes data were obtained from stage I – III TNBC patients treated with NAC in two centers in Korea. For spatial TIL analysis, we used Lunit SCOPE IO, an AI-powered H&E Whole-Slide Image (WSI) analyzer, which identifies and quantifies TIL within the cancer or stroma area. Lunit SCOPE IO was developed with a 13.5 x 109 micrometer2 area and 6.2 x 106 TIL from 17,849 H&E WSI of multiple cancer types, annotated by 104 board-certified pathologists. iTIL score and sTIL score were defined as area occupied by TIL in the intratumoral area (%) and the surrounding stroma (%), respectively. Immune phenotype (IP) of each slide was defined from spatial TIL calculation, as inflamed (high TIL density in tumor area), immune-excluded (high TIL density in stroma), or desert (low TIL density overall). Results: A total of 954 TNBC patients treated from 2006 to 2019 were included in this analysis. pCR (ypT0N0) was confirmed in 261 (27.4%) patients. The neoadjuvant regimens used were mostly anthracycline (97.8%) and taxane (75.1%) -based, with 116 (12.1%) patients receiving additional platinum and 41 (4.3%) patients treated as part of immune checkpoint inhibitor or PARP inhibitor clinical trials. The median iTIL score and sTIL score were 4.3% (IQR 3.2 – 5.8) and 8.1% (IQR 6.3 – 13.4), respectively. The mean iTIL score was significantly higher in patients who achieved pCR after NAC (5.8% vs. 4.5%, p < 0.001), and a similar difference was observed with sTIL score (12.1%.1 vs. 9.4%, p < 0.001). iTIL score was found to remain as an independent predictor of pCR along with cT stage and Ki-67 in the multivariable analysis (adjusted odds ratio 1.211 (95% CI 1.125 – 1.304) per 1 point (%) change in the score, p

189 Background: ctDNA is an attractive alternative to tissue for its easy accessibility and real time representation of systemic tumor profile. We explored the utility of ctDNA profiling during the course of mCRC treatment. Methods: Serial blood samples were obtained from mCRC patients before and during first-line palliative chemotherapy at fixed intervals (after every four cycles) until confirmed disease progression. ctDNA was sequenced using targeted next-generation sequencing (NGS) platform with 106 genes. Changes of ctDNA profile and treatment outcome were comprehensively analyzed. Results: A total of 272 samples from 62 patients were analyzed. In the pre-treatment blood samples, 56 (90.3%) of patients had detectable ctDNA mutations including single nucleotide variants, short insertions/deletions and copy number changes (median 4.5 mutations/ patient, range 0 - 133). In 31 (50.0%) patients who had tissue NGS panel results performed in the clinic, overall concordance between mutations from ctDNA and tissue was 86.5%. In three patients, ctDNA mutational profiles were found to be completely different from tissue profiles. At further investigation, these patients were found to have a separate primary cancer in their colon. At the time of the first follow-up, most (98.0%) patients showed decrease of ctDNA from baseline, represented by average variant allele frequency (VAF) changes of all ctDNA mutations found. Clearance of ctDNA was achieved in 40 (78.4%) patients and was associated with longer progression-free survival (median PFS 11.8 moths in ctDNA clearance (+) vs. 4.7 months in ctDNA clearance (-), p < 0.001). The ctDNA clearance at the same time point was able to further discriminate the patients in same category by RECIST 1.1. Serial follow-up monitoring revealed three patterns of ctDNA changes at the time of clinical progressive disease (PD): 1) re-emergence or re-increase of baseline ctDNA mutations, 2) emergence of new resistance mutations, 3) radiologic PD without evidence of ctDNA progression. In the patients with detectable ctDNA at PD, the ctDNA progression preceded radiologic progression in 25 (58.1%) patients by median of 3.3 months. The patients in clinical PD without ctDNA progression showed different patterns of metastasis having mainly extrahepatic spread, while 77.8% of the patients with ctDNA progression had their progression confirmed in liver metastasis. Diverse resistant mutations and gene amplifications in PD patients were discovered by ctDNA sequencing. For seven (16.3%) of the PD patients, the newly identified mutations could be potential candidates of targeted therapy or clinical trial. Conclusions: ctDNA profile provided additional information to conventional evaluation methods and reflected dynamic changes. ctDNA monitoring may improve precise treatment decision-making for individual patients.

We report a dual-immunopatterned microfluidic device for capturing both epithelial and mesenchymal circulating tumor cells (CTCs) simultaneously in a single device using the two antibodies of anti-epithelial cell adhesion molecule (EpCAM) antibody and newly developed anti-63B6 antibody. In addition to the conventional epithelial antibody of anti-EpCAM, our in-house produced anti-63B6 antibody targets mesenchymal stem cell-like cancer cells and intermediate cancer cells, thus overcoming limitation of the conventional single anti-EpCAM based CTC isolations. These two antibodies are immobilized to each top and bottom layer of the present device and the combination of two layers forms a circular chamber with the center inlet. The mutual complementary cell isolation through competing reaction in different velocity zones between mesenchymal and epithelial antibodies enables the precise screening and profiling of CTCs depending on their positivity and degree of epithelial/mesenchymal surface antigen expression, which may differ in compliance with disease status. From the experiments using epithelial and mesenchymal-like cancer cells, the present device captures 94.47% of cancer cells, which is substantially higher than the EpCAM-only-based method in terms of heterogeneous cancer cell isolation including mesenchymal–like cancer cells. Patient blood samples were employed to assess the clinical application of the present device for examining the patient status based on their CTC heterogeneity. The CTCs captured by both antibodies exhibit considerably varied expression profiles of epithelial protein including cytokeratin and EpCAM. The present device facilitates the isolation of heterogeneous subtypes of CTCs. These undiscovered heterogeneities would be helpful for precise analysis of CTCs to find their underlying meaning in cancer progression.

Although regorafenib has demonstrated survival benefits in patients with metastatic colorectal and gastrointestinal stromal tumors, no proven biomarker has been identified for predicting sensitivity to regorafenib. Here, we investigated preclinical activity of regorafenib in gastric and colorectal cancer cells to identify genetic alterations associated with sensitivity to regorafenib. Mutation profiles and copy number assays of regorafenib target molecules indicated that amplification of fibroblast growth factor receptor 2 (FGFR2) was the only genetic alteration associated with in vitro sensitivity to regorafenib. Regorafenib effectively inhibited phosphorylation of FGFR2 and its downstream signaling molecules in a dose-dependent manner and selectively in FGFR2-amplified cells. Regorafenib induced G1 arrest (SNU-16, KATO-III) and apoptosis (NCI-H716); however, no significant changes were seen in cell lines without FGFR2 amplification. In SNU-16 mice xenografts, regorafenib significantly inhibited tumor growth, proliferation, and FGFR signaling compared to treatment with control vehicle. Regorafenib effectively abrogates activated FGFR2 signaling in FGFR2-amplified gastric and colorectal cancer and, therefore, might be considered for integration into treatment in patients with FGFR2-amplified gastric and colorectal cancers.

BackgroundLittle is known about bridging clonal heterogeneity into the resistance of immune checkpoint inhibitors (ICI). Recent reports showed that excluded tumor-infiltrating lymphocytes (TIL) into stroma assessed by an artificial intelligence (AI)-powered spatial TIL analyzer, Lunit SCOPE IO, was related to loss-of-heterozygosity of HLA genes which would be one of crucial resistance pathways of ICI.1 In the current study, we hypothesized that Immune-excluded phenotype called by Lunit SCOPE IO would be related to clonal heterogeneity resulted from genome-wide accidents during early carcinogenesis which may cause an improper targeting of TIL for diverse clones with multiple genomic aberrations.MethodsFor spatial TIL analysis, we applied Lunit SCOPE IO1 which automatically detects TIL and segmentizes cancer area and stroma, then it classified Immune phenotype of 1 mm2-sized grid in H&E image. Inflamed score or Immune-excluded score were defined as the proportion of Inflamed phenotype, which is high intra-tumoral TIL density, or Immune-excluded phenotype, which is exclusively high TIL density only in stroma, within a whole-slide image, respectively. We evaluated the correlation of Immune phenotype with APOBEC mutational signature by single-base substitution (SBS) signature 2 and/or SBS13,2 whole-genome doubling, and subclonal genome fraction which reflects intra-tumoral heterogeneity,3 and clusters of T cell receptor (TCR) repertoire 4 derived from previous reports of The Cancer Genome Atlas (TCGA), consists of 7,467 tumor samples from 22 cancer types.Abstract 830 Table 1Correlation between immune phenotype and clonal evolution of cancer [* Median (95% confidence interval)]ResultsIn the TCGA pan-carcinoma database, APOBEC mutational signature was significantly correlated with increased ratio of cancer stroma to cancer epithelium (median 0.866 vs 1.19, fold change +37.4%), and increased TIL density in cancer stroma (median 558 vs 764 / mm2, fold change +36.9%), but it was not correlated with intra-tumoral TIL density (median 63 vs 59 / mm2, fold change -6.3%). Interestingly, Immune-excluded score (IES) called by Lunit SCOPE IO was positively correlated with APOBEC mutational signature as well as expression levels of APOBEC1, APOBEC3A, and APOBEC3B, whole-genome doubling, and subclonal genome fraction, respectively, while Inflamed score (IS) or immune cytolytic activity (GZMA and PRF1 expressions) was negatively or not significantly correlated to those variables (table 1). TCR repertoire was expanded in the tumor samples with high IS (spearman rho = 0.279), but it was not increased in those with high IES (spearman rho = -0.0595).ConclusionsThere is a significant correlation between distinct TIL deposition in stroma, or Immune-excluded phenotype, with APOBEC-attributed clonal expansion of cancer, without proper expansion of TCR repertoire.ReferencesOck CY, Park C, Paeng K, Yoo D, Kim S, Park S, Lee SH, Mok T, Bang YJ. Artificial intelligence-powered spatial analysis of tumor-infiltrating lymphocytes reveals distinct genomic profile of immune excluded phenotype in pan-carcinoma. Cancer Res 2021;81(Supp 13):1908.Alexandrov LB, Kim J, Haradhvala NJ, Huang MN, Tian Ng AW, Wu Y, Boot A, Covington KR, Gordenin DA, Bergstrom EN, Islam SMA, Lopez-Bigas N, Klimczak LJ, McPherson JR, Morganella S, Sabarinathan R, Wheeler DA, Mustonen V, PCAWG Mutational Signatures Working Group, Getz G, Rozen SG, Stratton MR, PCAWG Consortium. The repertoire of mutational signatures in human cancer. Nature 2020;578(7793):94–101.Taylor AM, Shih J, Ha G, Gao GF, Zhang X, Berger AC, Schumacher SE, Wang C, Hu H, Liu J, Lazar AJ, Cancer Genome Atlas Research Network, Cherniack AD, Beroukhim R, Meyerson M. Genomic and functional approaches to understanding cancer aneuploidy. Cancer Cell 2018;33(4):676–689.e3.Zhang H, Liu L, Zhang J, Chen J, Ye J, Shukla S, Qiao J, Zhan X, Chen H, Wu CJ, Fu YX, Li B. Investigation of antigen-specific T-Cell receptor clusters in human cancers. Clin Cancer Res 2020;26(6):1359–1371.

Purpose The purpose of this study was to assess current levels of awareness of clinical trials (CTs), perceptions regarding their benefits and willingness to participate to CTs among Korean cancer patients. Materials and Methods From December 2012 to August 2015, we distributed questionnaires to cancer patients receiving systemic anti-cancer therapy at Seoul National University Hospital, Seoul, Korea. Results A total of 397 out of 520 requested patients (76.3%) responded to the survey. Among the 397 patients, 62.5% were female and the median age was 52 years. Overall, 97.4% (387/397) answered that they have at least heard of CTs. When asked about their level of awareness, 23.8% (92/387) answered that they could more than roughly explain about CTs. The average visual analogue scale score of CT benefit in all patients was 6.43 (standard deviation, 2.20). Patients who were only familiar with the term without detailed knowledge of the contents had the least expectation of benefit from CTs (p=0.015). When asked about their willingness to participate in CTs, 56.7% (225/397) answered positively. Patients with higher levels of awareness of CTs showed higher willingness to participate (p < 0.001). Heavily treated patients and patients with previous experience regarding CTs also showed a higher willingness to participate (p < 0.001). The perceived benefit of CTs was higher in the group willing to participate (p=0.026). Conclusion The patient’s level of awareness regarding CTs was positively related to the positive perception and willingness to participate. Although the general awareness of CTs was high, a relatively large proportion of patients did not have accurate knowledge; therefore, proper and accurate patient education is necessary.

Background: Immune checkpoint inhibitors (ICIs) were recently introduced into routine clinical practice, but the immunogenicity and safety of influenza vaccination in cancer patients receiving ICIs have not been elucidated. We explored immunogenicity and safety in cancer patients receiving ICIs compared to cancer patients receiving cytotoxic chemotherapy. Methods: Adult cancer patients receiving ICIs or cytotoxic agents were prospectively enrolled in a 1:2 ratio. They received an intramuscular seasonal quadrivalent influenza vaccine on day 1 of the chemotherapeutic cycle. The serum hemagglutination inhibition (HAI) antibody titers were examined before and 4 weeks after vaccination. The primary endpoint was seroprotection rate and secondary endpoints were seroconversion rate and geometric mean antibody titer. Immune-related adverse events (irAEs) were screened by pre-defined measures. Findings: Among 154 eligible patients, 46 and 90 patients in the ICI and cytotoxic chemotherapy groups, respectively, were finally examined for HAI antibody titers. Seroprotection rates were higher in the ICI group than in the cytotoxic chemotherapy group (H1N1, 76% vs. 68%, P=0.111; H3N2, 89% vs. 70%, P=0.005; B-Yamagata, 83% vs. 54%, P=0.002; B-Victoria, 85% vs. 48%, P

Although MEK blockade has been highlighted as a promising antitumor drug, it has poor clinical efficacy in KRAS mutant colorectal cancer (CRC). Several feedback systems have been described in which inhibition of one intracellular pathway leads to activation of a parallel signaling pathway, thereby decreasing the effectiveness of single-MEK targeted therapies. Here, we investigated a bypass mechanism of resistance to MEK inhibition in KRAS CRC. We found that KRAS mutant CRC cells with refametinib, MEK inhibitor, induced MIF secretion and resulted in activation of STAT3 and MAPK. MIF knockdown by siRNA restored sensitivity to refametinib in KRAS mutant cells. In addition, combination with refametinib and 4-IPP, a MIF inhibitor, effectively reduced the activity of STAT3 and MAPK, more than single-agent treatment. As a result, combined therapy was found to exhibit a synergistic growth inhibitory effect against refametinib-resistant cells by inhibition of MIF activation. These results reveal that MIF-induced STAT3 and MAPK activation evoked an intrinsic resistance to refametinib. Our results provide the basis for a rational combination strategy against KRAS mutant colorectal cancers, predicated on the understanding of cross talk between the MEK and MIF pathways.

Background Although induction chemotherapy can reduce distant metastases in locally advanced head and neck squamous cell carcinoma (HNSCC), overall survival (OS) improvement because of induction chemotherapy has not been confirmed. Methods We reviewed medical records of 224 patients diagnosed with locally advanced HNSCC who were treated with induction chemotherapy followed by concurrent chemoradiotherapy (CRT; induction chemotherapy/CRT; N = 144) and CRT alone (N = 80) from 2005 to 2013. We analyzed OS and progression-free survival (PFS). Results The 3-year OS rate was significantly higher in the induction chemotherapy/CRT group compared to the CRT group (74.0% vs 62.7%; p = .045). The 3-year PFS rate was 64.6% in the induction chemotherapy/CRT group and 54.1% in the CRT group (p = .060). Subgroup analysis showed patients with high N classification (N2 or N3) oropharyngeal cancer had greater benefits when treated with induction chemotherapy/CRT. Conclusion Induction chemotherapy plus CRT improved OS, compared to CRT alone in locally advanced HNSCC, especially with high N classification. © 2015 Wiley Periodicals, Inc. Head Neck 38: 277–284, 2016

Background Evidences suggest an association between leukocytosis and thrombotic or hemorrhagic complication in polycythemia vera (PV) and essential thrombocythemia (ET), but clinical implication is not well known. Objective To evaluate whether leukocyte burden during follow-up is related to thrombotic or hemorrhagic events in PV and ET. Patients/Methods We retrospectively analyzed patients with PV or ET treated at Seoul National University Bundang Hospital, Korea. Time-weighted averages of leukocytes during the follow-up period were defined as leukocyte burden and were calculated for each patient and compared between patient subgroups. In each patient with events, leukocyte burden for the 3-month period before the event was compared with that for the entire follow-up period. Results In 102 patients with PV or ET, 35 events (16 thrombotic, 19 hemorrhagic) occurred in 29 patients (median follow-up, 54months). Leukocyte burden were significantly higher in patients with events than in event-free patients (12,015×10 3 /μL vs. 9,567×10 3 /μL, P =0.003). The difference was more prominent in ET patients than in PV patients, and in patients with hemorrhagic events than in those with thrombotic events. In patients with events, the leukocyte burden in the pre-event period was higher than in the entire follow-up period (16,767×10 3 /μL vs. 12,015×10 3 /μL, P =0.002). In all patients, leukocyte burden during entire follow-up period of 11,000×10 3 /μL or higher was an independent risk factor for vascular events. Conclusion In PV or ET patients, leukocyte burden during disease course is related to increased incidence of thrombotic or hemorrhagic events.

Organoids are known to best in vitro model system which mostly mimic genetic, phenotypic feature of its origin. And it is expected and suitable to variable disease modeling and study. For cancer modeling using organoids as co-clinical model, our group derived organoids from 40 colorectal tumor including lymph node, terminal ileum metastatic tumor and ascites. Whole exome sequencing of matched tumor organoids and tissues was performed and their somatic mutation concordance was analyzed. As a results, Organoids reflect their genetic statues of the original tumor tissue and their phenotypic features are maintained. In order to prove the appliance of these organoids as a co-clinical model, clinical drugs on colorectal cancer such as 5-Fluorouracil, oxaliplatin, SN38 and cetuximab were tested. The drug results reflected the actual clinical outcome of the corresponding patients. To find the precise drug treatment option for conventional chemo-refractory patients, we performed 134 anti-cancer drug library screening. Organoids with specific mutations were sensitive to drugs which target these corresponding mutations. For instance, organoid with RNF43 mutation was sensitive to porcupine inhibitor which suppresses auto- and paracrine WNT- driven growth. In conclusion, we suggest that patient derived organoids can be applied in cancer treatment as a co-clinical model, due to their highly correlated genetic information and drug sensitivity with those of the patients themselves. Citation Format: Young-Won Cho, Hwang-Phill Kim, Dong Wook Min, Yoojoo Lim, Sang-Hyun Song, Sae-Won Han, Tae-You Kim. Application of patients derived organoids as co-clinical model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 36.

This study was performed to evaluate whether fluorine-18 fluorodeoxyglucose positron-emission tomography/computed tomography (FDG PET/CT) could predict treatment outcome of regorafenib in metastatic colorectal cancer (mCRC).Previously treated refractory mCRC patients were enrolled into a prospective biomarker study of regorafenib. For this sub-study, the results of FDG PET/CT scans at baseline and after two cycles of treatment were analyzed. Various metabolic parameters obtained from PET images were analyzed in relation to treatment outcome.A total of 40 patients were evaluable for PET image analysis. Among various PET parameters, total lesion glycolysis (TLG) measured in the same target lesions for RECIST 1.1 analysis were the most significant in predicting prognosis, with the lowest p-value observed in TLG calculated using the margin threshold of 40 % (TLGMeasurement of TLG can predict treatment outcome of regorafenib in mCRC.

FDG PET is effective in treatment response evaluation of cancer. However, there is no standard method for quantitative evaluation of FDG PET, particularly regarding cytostatic drugs. We compared various FDG PET quantitative methods in terms of response determination. A total of 39 refractory metastatic colorectal cancer patients who received a multikinase inhibitor treatment were included. Baseline and posttreatment FDG PET/CT scans were performed before and two cycles after treatment. Standardized uptake value (SUV) and total lesion glycolysis (TLG) values using various margin thresholds (30–70 % of maximum SUV with increment 10 %, twice mean SUV of blood pool, SUV 3.0, and SUV 4.0) were measured, with measurement target of the hottest lesion or a maximum of five hottest lesions. Treatment response by the PERCIST criteria was also determined. Predictive values of the PET indexes were evaluated in terms of the treatment response determined by the RECIST 1.1 criteria. The agreement rate was 38 % between response determined by the PERCIST and the RECIST criteria (κ = 0.381). When patients were classified into disease control group (PR, SD) and non-control group (PD) by the RECIST criteria, percent changes of TLG with various margin thresholds (particularly, 30–50 % of maximum SUV) exhibited significant differences between the two groups, and high diagnostic power for the response by the RECIST criteria. TLG-based criteria, which used a margin threshold of 50 % of maximum SUV, exhibited a high agreement with the RECIST criteria compared with the PERCIST criteria (κ = 0.606). In metastatic colorectal cancer, FDG PET/CT could be effective for treatment response evaluation by using TLG measured by margin thresholds of 30–50 % of maximum SUV. Further studies are warranted regarding the optimal cutoff values for this method.

Background Regorafenib induces distinct radiological changes that represent its anti-angiogenic effect. However, clinical implication of the changes is unclear. Methods Tumor attenuation as measured by Hounsfield units (HU) in contrast-enhanced computed tomography (CT) and cavitary changes of lung metastases were analyzed in association with treatment outcome of metastatic colorectal cancer patients (N = 80) treated with regorafenib in a prospective study. Results 141 lesions in 72 patients were analyzed with HU. After 2 cycles of regorafenib, 87.5% of patients showed decrease of HU (Median change -23.9%, range -61.5%–20.7%). Lesional attenuation change was modestly associated with metabolic changes of 18-fluoro-deoxyglucose positron emission tomography-CT (Pearson’s r = 0.37, p = 0.002). Among 53 patients with lung metastases, 17 (32.1%) developed cavitary changes. There were no differences in disease control rate, progression-free survival, or overall survival according to the radiological changes. At the time of progressive disease (PD) according to RECIST 1.1, HU was lower than baseline in 86.0% (43/50) and cavitary change of lung metastasis persisted without refilling in 84.6% (11/13). Conclusion Regorafenib showed prominent anti-angiogenic effect in colorectal cancer, but the changes were not associated with treatment outcome. However, the anti-angiogenic effects persisted at the time of PD, which suggests that we may need to develop new treatment strategies.

The cell-free DNA (cfDNA) represents a minimally invasive and alternative source of tumor DNA for molecular profiling. Despite next-generation sequencing (NGS) technique is qualified for genotyping cancer using cfDNA as a noninvasive method, it has caused problems as sequencing error and reproducibility. cfDNA in plasma and gDNA of Peripheral Blood Mononuclear Cells (PBMC) were isolated from each 54 advanced colorectal cancer patients. 39 available tumor tissues were isolated from same patients. Deep target-sequencing was performed with paired-end library enriched exons of 10 genes which are recurrently mutated in colorectal cancer. To reduce sequencing error, we devised ‘Denoising’ and calculated concordance of somatic variants between cfDNA and tumor tissue sequencing data. In addition, correlation of concordance data was analyzed with the clinical information. As a result, we selectively could detect clinically important somatic alteration among low/high variant allele frequency (0.31%~79.42%). For somatic alteration of 10 genes, sensitivity, specificity and accuracy were increased from 84.5%, 74.6% and 76.9% to 87.6%, 92.0% and 91.1% respectively after ‘Denoising’. On the other hand, patients with high cfDNA concentration(>50ng/ml) had higher somatic mutant fragments and larger metastatic lesion in liver than patients who have low cfDNA concentration. Our study showed that denoised deep target-sequencing is a suitable method for cfDNA genotyping and provides insights into strategies for monitoring metastatic lesion of advanced colorectal cancer. Citation Format: Jun-Kyu Kang, Hwang-Phill Kim, Seul-Ki Cheon, Ye-Lim Park, Yoojoo Lim, Sae-Won Han, Tae-You Kim. Noninvasive approach to assess metastatic lesion of advanced colorectal cancer by denoised deep target sequencing [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1800. doi:10.1158/1538-7445.AM2017-1800

KRAS is a frequently mutated gene in colorectal cancer. In addition, PIK3CA mutations commonly co-exist with KRAS mutations and lead to additive activation of the PI3K/mTOR signaling pathway. Here, we investigated preclinical activity of gedatolisib, a PI3K/mTOR dual inhibitor, to identify mechanism of inhibition of PI3K/mTOR in 28 colorectal cancer (CRC) cells. Cells specifically with PIK3CA mutation were sensitive while those with KRAS mutation were resistant to gedatolisib. 9 out of 28 CRC cells harbor PIK3CA & KRAS co-mutation and 7 out them were shown to be sensitive to gedatolisib. However, HCT15 and LS174T cells were resistant. We identified that resistant cell lines have high activity of GSK3B and TCF7 frameshift mutation (465insertC466;H155fs*), which functions as positive regulator of WNT/b-catenin pathway. The effects of GSK3B-knockdown showed decreased activity of mTOR downstream molecules in gedatolisib-treated resistant cells. Interestingly, these effects also caused a decrease in activity of WNT/b-catenin pathway. In addition, combination treatment of gedatolisib and CHIR-99021, GSK3B inhibitor, resulted in significantly enhanced cytotoxicity against gedatolisib-resistant TCF7 frameshift mutant cells. Taken together, these show that aberrant regulation of WNT/b-catenin pathway and high activity of GSK3B by TCF7 frameshift mutation cause resistance to PI3K/mTOR dual inhibitor. Inhibition of GSK3B activity in colorectal cancer cells with KRAS and PIK3CA co-mutations increases sensitivity to PI3K/mTOR dual inhibitor. Citation Format: Ye-Lim Park, Hwang-Phill Kim, Seul-Ki Cheon, Jun-Kyu Kang, Yoojoo Lim, Sang-Hyun Song, Sae-Won Han, Tae-you Kim. Activation of WNT/b-catenin signaling results in resistance to PI3K/mTOR dual inhibitor in co-existing KRAS and PIK3CA mutant colorectal cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5214. doi:10.1158/1538-7445.AM2017-5214

Although MEK blockade has been highlighted as a promising anti-tumor drug, it has poor clinical efficacy in KRAS mutant colorectal cancer. Several feedback systems have been described in which inhibition of one intracellular pathway leads to activation of a parallel signaling pathway, thereby decreasing the effectiveness of single-MEK targeted therapies. In this study, we describe a feedback mechanism in which MEK inhibition leads to activation of macrophage migration inhibitory factor (MIF)-induced stat3 signaling pathway in KRAS mutant colorectal cancer (CRC) cells. We found that KRAS mutant CRC cells with refametinib, MEK inhibitor, induced MIF secretion and resulted in activation of Stat3. MIF knockdown by siRNA partially restored sensitivity to refametinib in KRAS mutant cells. In addition, combination with refametinib and 4IPP, a MIF inhibitor, effectively reduced the activity of stat3 and MAPK, more than single agent treatment. As a result, combined therapy was found to exhibit a synergistic growth inhibitory effect against refametinib-resistant cells by downregulating MIF expression. These results reveal that MIF-induced stat3 activation evoked an intrinsic resistance to refametinib. Our results provide the basis for a rational combination strategy against KRAS mutant colorectal cancers, predicated on the understanding of cross-talk between the MEK and MIF pathways. Citation Format: Seul-Ki Cheon, Hwang-Phill Kim, Ye-Lim Park, Si Hyun Lee, Jun-Kyu Kang, Yoojoo Lim, Sang-Hyun Song, Sae-Won Han, Tae-You Kim. MIF-induced stat3 activation promotes resistance to MEK blockade in KRAS mutant colorectal cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3167. doi:10.1158/1538-7445.AM2017-3167

10008 Background: Cancer-related fatigue(CRF) is a common and severe symptom in patients with cancer. The purpose of this study is to evaluate the anti-fatigue effect of Korean Red Ginseng(Steamed Panax ginseng C.A. Meyer) on patients with colorectal cancer. Methods: 438 colorectal cancer patients in treatment with mFOLFOX-6 regimen were randomly assigned to either the Korean Red Ginseng[KRG](n = 219) or placebo(n = 219) group and received 2,000 mg/day test substances for 16 weeks. The primary endpoint was the Area Under Curve(AUC) of Brief Fatigue Inventory(BFI) over 16 weeks. The AUC and change from the baseline were calculated. The frequency and types of adverse events were determined by the National Cancer Institute's Common Terminology Criteria for Adverse Events, version 4.0. Results: 438 colorectal cancer patients were enrolled from 15 institutions. Changes from the baseline in the global BFI were 78.54(Standard deviation [SD] = 16.91) in KRG group vs. 75.89(SD = 16.85) in placebo group at 16 weeks(P = 0.0363). Changes from the baseline in the Usual Fatigue were 76.15 (SD = 17.08) in KRG group vs. 73.08(SD = 17.03) in placebo group at 16 weeks(P = 0.0454). Changes from the baseline in the Mood were 80.46(SD = 17.16) in KRG group vs. 77.88(SD = 17.59) in placebo group at 16 weeks(P = 0.0086). Changes from the baseline in the Relations with Others were 82.09(SD = 17.49) in KRG group vs. 78.67(SD = 17.90) in placebo group at 16 weeks(P = 0.0080). Changes from the baseline in the Walking ability were 82.70(SD = 17.28) in KRG group vs. 80.77(SD = 16.47) in placebo group at 16 weeks(P = 0.0090). Changes from the baseline in the Enjoyment of life were 79.53(SD = 19.53) in KRG group vs. 77.51(SD = 18.02) in placebo group at 16 weeks(P = 0.0150). Toxicities per self-report and CTCAE grading did not differ statistically significantly between the groups. Conclusions: The data supports benefits of consuming 2,000 mg KRG water extract powder daily on CRF over 16-week period. There were no discernible toxicities associated with the treatment. More studies on mechanisms of KRG to guide its role in CRF improvement are needed. Clinical trial information: NCT02039635.

Although induction chemotherapy can reduce distant metastases in locally advanced head and neck squamous cell carcinoma (HNSCC), overall survival (OS) improvement because of induction chemotherapy has not been confirmed.We reviewed medical records of 224 patients diagnosed with locally advanced HNSCC who were treated with induction chemotherapy followed by concurrent chemoradiotherapy (CRT; induction chemotherapy/CRT; N = 144) and CRT alone (N = 80) from 2005 to 2013. We analyzed OS and progression-free survival (PFS).The 3-year OS rate was significantly higher in the induction chemotherapy/CRT group compared to the CRT group (74.0% vs 62.7%; p = .045). The 3-year PFS rate was 64.6% in the induction chemotherapy/CRT group and 54.1% in the CRT group (p = .060). Subgroup analysis showed patients with high N classification (N2 or N3) oropharyngeal cancer had greater benefits when treated with induction chemotherapy/CRT.Induction chemotherapy plus CRT improved OS, compared to CRT alone in locally advanced HNSCC, especially with high N classification.