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Background: Dual HER2 blockade with trastuzumab and pertuzumab combined with docetaxel (DHP) is the standard first-line treatment option for patients with HER2-positive metastatic breast cancer. However, HER2 positivity alone often fails to predict treatment outcome of HER2 targeted therapy. The magnitude of HER2 immunohistochemical staining (IHC) and HER2/CEP17 ratio from in situ hybridization (ISH) is a well-known predictive biomarker for HER2 targeted therapy. In the neo-adjuvant setting, patients with HER2 IHC 3+ have higher pathologic complete response (pCR) rate compared to HER2 IHC< 3+ with HER2 ISH positive. In addition, higher HER2/CEP17 ratio is associated with higher pCR rate in HER2-positive breast cancer patients treated with dual HER2 blockade regimens. However, there is no data whether there is an association between HER2/CEP17 ratio and treatment outcome of DHP regimen in patients with advanced of metastatic breast cancer especially among those with HER2 IHC 3+. Methods: We performed a retrospective cohort study with patients with locally advanced or metastatic HER2-positive breast cancer who were treated with first-line palliative DHP regimen between August 2008 and January 2021 at Seoul National University Hospital. In the clinical setting, HER2 IHC 3+ is defined as HER2 positive and no further ISH testing is required. Additional ISH was performed in patients with HER2 IHC 3+ without archival HER2 ISH results. The association between HER2/CEP17 ratio and treatment outcome was assessed. Results: In total, 165 patients were included with a median follow-up duration of 28.0 months. Among the 165 patients, 35 patients had archival ISH result and additional ISH was performed in 53 patients. The correlation between HER2/CEP17 ratio and treatment outcome was assessed in 88 patients. Cox proportional hazard analysis revealed that HER2/CEP17 ratio is correlated with PFS (HR 0.23, 95% CI 0.11-0.49, p < 0.001). When dichotomized by the median HER2/CEP17 ratio of 4.17, patients with higher HER2/CEP17 ratio had significantly longer PFS (37.5 vs. 17.4 months, p = 0.003) and numerically higher ORR (54.5% vs. 34.1%, p = 0.085). Multivariate analysis revealed that HER2/CEP17 ratio is an independent prognostic factor for PFS (HR 0.72, p = 0.001). Of 88 patients with ISH results, 25 had HER2 IHC 1+ or 2+ and 63 had HER2 IHC 3+. HER2/CEP17 ratio was associated with PFS in both HER2 IHC 1+/2+ patients (HR 0.12, 95% CI 0.02-0.88, p = 0.037) and HER2 IHC 3+ patients (HR 0.18, 95% CI 0.07-0.49, p = 0.001). Patients with higher HER2/CEP17 ratio had longer PFS in both HER2 IHC 1+/2+ patients (28.6 vs. 12.9 months, p = 0.003) and HER2 IHC 3+ patients (Not reached vs. 18.3 months, p = 0.005) when dichotomized by the median HER2/CEP17 of 2.95 and 4.75, respectively. Conclusion: This is the first study to report that higher HER2/CEP17 ratio is associated with longer PFS in HER2-positive advanced breast cancer patients treated with palliative first-line DHP. The strength of this study is that we identified prognostic role of ISH even in patients with HER2 IHC 3+. It would be helpful to perform ISH not only in patients whose HER2 IHC is ambiguous, but also in patients with HER2 IHC 3+ to make better prediction of treatment outcome. Table 1. Patient characteristics. Citation Format: Jeongmin Seo, Jiwon Koh, Dae-Won Lee, Han Suk Ryu, Kyung-Hun Lee, Tae-Yong Kim, Seock-Ah Im. High HER2/CEP17 ratio is associated with better treatment outcomes in advanced HER2-positive breast cancer treated with pertuzumab, trastuzumab, and docetaxel regardless of HER2 2+ or 3+ results [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-04-01.

This study was designed to evaluate the prognostic implication of gross extrathyroidal extension (ETE) invading the strap muscles after thyroid lobectomy in patients with 1-4 cm papillary thyroid cancer (PTC).This retrospective cohort study included patients with 1-4 cm PTC who underwent thyroid lobectomy from 2005 to 2012. Overall, 595 patients were enrolled after excluding patients with aggressive variants of PTC, gross ETE into a major neck structure, and lateral cervical lymph node (LN) metastasis. We evaluated the risk factors for structural recurrence after lobectomy in 1-4 cm PTC.Seventy-eight patients (13.1%) had gross ETE invading only the strap muscles. During the median follow-up period of 7.7 years, structural recurrence was confirmed in 35 patients (5.9%). The presence of gross ETE was an independent risk factor for structural recurrence (hazard ratio 2.54, 95% confidence interval 1.19-5.44; p = 0.016). Subgroup analysis of patients with gross ETE showed that 11 and 47 patients had low- and intermediate-risk LN metastasis, respectively. A significant difference in recurrence-free survival was observed according to the degree of cervical LN metastasis (p = 0.03). Those without LN metastasis or low-risk LNs had a 75% lower risk of recurrence when compared with those with both gross ETE and intermediate-risk LNs.Gross ETE and intermediate-risk cervical LN metastasis were associated with a significantly high risk of recurrence after lobectomy in patients with 1-4 cm PTC. Completion thyroidectomy would be considered in this subgroup of patients but not in all patients with gross ETE invading only the strap muscles.

PurposeWe aimed to assess the real-world efficacy of nab-paclitaxel in metastatic breast cancer patients.Materials and MethodsThis is a retrospective study performed in two tertiary referral hospitals in Korea. Patients with metastatic breast cancer treated with nab-paclitaxel (Abraxane®) between March 2016 and March 2020 were enrolled.ResultsA total of 102 patients with metastatic breast cancer were included. Patients were heavily pre-treated with a median of four prior lines of chemotherapy (5 lines when including endocrine therapy in hormone-receptor-positive patients), and 66 patients (64.7%) were exposed to taxanes in the metastatic setting. According to St. Gallen molecular subtypes, 36 patients (35.3%) were luminal A, 28 (27.5%) were luminal B, 18 (17.7%) were human epidermal growth factor receptor 2–positive and 20 (19.6%) had triple-negative disease. Fifty patients (49.0%) were treated with a 3-weekly regimen (260 mg/m2 on day 1 every 3 weeks), and 52 (51.0%) were treated with a weekly regimen (100 mg/m2 every week). Objective response rate was 22.9%. After a median follow-up of 22.0 months, median progression-free survival (PFS) was 4.0 months (95% confidence interval [CI], 2.6 to 4.8) and median overall survival was 8.7 months (95% CI, 7.5 to 11.2). Patients treated with weekly regimen had longer PFS compared to 3-weekly regimen (5.5 vs. 2.3 months, p < 0.001). Multivariate analysis revealed the treatment regimen as an independent prognostic factor for PFS. There was no grade 3 or 4 hypersensitivity reaction.ConclusionThis real-world data shows that nab-paclitaxel is a reasonable treatment option in heavily pre-treated and/or taxane-exposed metastatic breast cancer patients.

Background PARP inhibitors have proven efficacy in breast cancer patients with germline BRCA1 or BRCA2 mutations (gBRCAmt) but also have potential to be effective in cancers with defects in homologous recombination (HR) DNA repair. Moreover, synergy between PARP inhibition and immune checkpoint blockade is expected based on increased mutation burden, neoantigen expression, and immunogenic cell death. Triple negative breast cancer (TNBC) or low estrogen receptor (ER)-positive breast cancers may have diverse defects in HR repair. Methods This is a window of opportunity, serial biopsy trial of olaparib and durvalumab before standard neoadjuvant chemotherapy for TNBC or low ER+ breast cancer (NCT03594396). Patients had clinical stage II/III TNBC or low ER+ HER2- breast cancers where ER was expressed in 10% or lower in tumor cells. Olaparib 300mg bid was given for 4 weeks without rest. One dose of durvalumab 1500mg was given on day 15. Study tumor biopsy and blood sample were taken before the study treatment, after 2 weeks of olaparib before durvalumab, and 2 weeks after durvalumab at the completion of 4 weeks of olaparib. FDG-PET/MRI was taken at baseline, after 2 weeks, after 4 weeks of study treatment, and computed tomography (CT) scan at baseline and after 4 weeks. After the study treatment, standard neoadjuvant chemotherapy with 4 cycles of doxorubicin+cyclophosphamide followed by 4 cycles of docetaxel was given. Primary endpoint was the changes of tumor biology detected by serial tumor biopsy. Secondary endpoints were pathological complete response (pCR) rate, response rate, prediction of early metabolic response by functional HR status, and safety. Functional HR deficiency was assessed by counting RAD51 foci as a marker for HR repair in the baseline tumor tissues before and after 30Gy irradiation to induce DNA damage. Results Fifty-four female patients were enrolled (median age 40 years, range 24-68). ER was negative (TNBC) in 43 patients and low-positive in 11 patients. Clinical stage was II in 25 patients and III in 29 patients, and axillary lymph node involvement was in 47 patients. gBRCAmt was assessed in 53 patients and 16 (30.1%) harbored pathogenic mutations. Functional HR status as measured by RAD51 foci formation was deficient in 27 (50%) patients and proficient in 27 (50%) patients. Functional HR deficiency was related with early metabolic response by FDG-PET after 2 weeks of olaparib (response in 17/27 HR-deficient tumors [63.0%] vs. 7/27 HR-proficient tumors [25.9%]; p=.006). After 4 weeks of olaparib and durvalumab, HR-deficiency was still related to metabolic response (23/27 vs. 17/27, respectively; p=.062) but HR-proficient tumors also showed metabolic decline. Moreover, HR deficiency was also related with RECIST response measured by CT after 4 weeks (17/27 vs. 9/27; p=.029). As of June 2021, 40 patients completed the neoadjuvant treatment and surgery; among those, 30 achieved pCR (pCR rate 75%). Among 13 patients with gBRCAmt who underwent surgery, 11 achieved pCR (84.6%). Updated results on pCR will be presented. Conclusions Olaparib and durvalumab followed by standard neoadjuvant chemotherapy shows very high pCR rate in TNBC or low ER+ stage II/III breast cancer. Functional HR status as measured by RAD51 foci formation was predictive of early metabolic response to olaparib. Genomic and transcriptomic analyses are underway in the samples before, during, and after olaparib and durvalumab. Citation Format: Seock-Ah Im, Kyung-Hun Lee, Ahrum Min, Daewon Lee, Tae Yong Kim, Han Suk Ryu, Jiwon Koh, Gi-Jeong Cheon, Yoon-Jung Shin, Yujin Kim, Hyeong-Gon Moon, Wonshik Han, Han-Byoel Lee, Morgan Diolaiti, David Quigley, Alan Ashworth, Nariya Cho. Window of opportunity trial of neoadjuvant olaparib and durvalumab for triple negative or low ER-positive breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr PD15-08.

CDK4/6 inhibitors such as palbociclib in combination with endocrine therapy (ET) have remarkablyimproved the outcome of patients with ER+/HER2- metastatic breast cancer (MBC). However, manypatients are intrinsically resistant to CDK4/6i therapy, and those who respond eventually acquireresistance. Although high baseline CCNE1 expression and rare alterations in RB1 and FAT1 geneshave been shown to be associated with CDK4/6i resistance, the molecular mechanisms of CDK4/6iresistance are complex and remain poorly understood. To better understand and overcome CDK4/6iresistance, we performed multi-omics profiling of paired tumor biopsies from ER+/HER2- MBCpatients treated with palbociclib combined with ET. Tumor biopsies taken at pre-treatment, on-treatment, and progressive disease (PD) from 71 patients were profiled using whole-exomesequencing (WES), whole-transcriptome sequencing (RNA-Seq) and IHC analysis. Ourcomprehensive analysis identified several tumor intrinsic molecular markers associated with worsePFS, including the Luminal B subtype (p=0.012, HR=2.593), BRCA1/2 pathogenic mutation (p=0.012,HR=2.67) and mutation signatures linked to APOBEC enzymatic activity (p=0.002, HR=3.19).Conversely, the estrogen response signature (p=0.006, HR=0.43) was associated with favorableprognosis. Unsupervised analysis revealed a cluster of tumors enriched in homologousrecombination deficiency (HRD) linked genomic scars that was associated with poor prognosis(p=0.005, HR=2.49). Of note, these HRD-high tumors responded even more poorly to treatment whenco-occurring with TP53 somatic mutations. Integrative analysis further identified three poorprognosis clusters (IC2-4) enriched in Luminal B, proliferative and HRD features when compared tothe favorable prognosis cluster (IC1).Comparing baseline vs. PD samples, we observed a pattern of post-treatment enrichment for the poorprognosis markers. In addition, breast cancer-associated genes such as BRCA1/2, TP53 and PTENharbored a higher prevalence of genomic alterations including somatic mutation, amplification,. deletion and gene fusion at PD. Cell cycle gene expression and signatures also markedly increased atPD compared to baseline whereas estrogen response signatures decreased. Upon diseaseprogression, tumors had frequently switched to molecular subtypes with aggressive and estrogenindependent characteristics, demonstrating high plasticity in response to CDK4/6i and ET treatment.These patterns of acquired resistance were validated by IHC analysis of cyclins E1 and E2, Ki67 andpRb. To investigate the genomic alterations responsible for acquired resistance, we compared 21paired baseline and PD samples. We observed that PD-specific RB1 loss-of-function events occurredwith higher prevalence than previously reported, underscoring a major role of cell cycle de-regulation in conferring resistance to CDK4/6 inhibition. In this prospective longitudinal multi-omicsstudy, we identified novel candidate biomarkers that can be used to improve prediction of responseto CDK4/6i. In addition, we derived new insights into the molecular mechanisms of drug resistanceto palbociclib plus ET that will help guide therapeutic strategies and drug development inHR+/HER2− MBC. Citation Format: Zhengyan Kan, Seock-Ah Im, Kyunghee Park, Ji Wen, Kyung-Hun Lee, Yoon-La Choi, Won-Chul Lee, Ahrum Min, Vinicius Bonato, Seri Park, Sripad Ram, Dae-Won Lee, Ji-Yeon Kim, Su Kyeong Lee, Won-Woo Lee, Jisook Lee, Miso Kim, Scott L. Weinrich, Han Suk Ryu, Tae Yong Kim, Stephen Dann, Diane Fernandez, Jiwon Koh, Song Yi Park, Shibing Deng, Eric Powell, Rupesh Kanchi Ravi, Jadwiga Bienkowska, Paul A. Rejto, Woong-Yang Park, Yeon Hee Park. Serial genomic profiling reveals molecular mechanisms of breast cancer resistance to palbociclib [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr PD2-08.

Olaparib, a potent PARP inhibitor, has been shown to have great anti-tumor effects in some tumor types. Although biliary tract cancer (BTC) is a good candidate for DNA damage response (DDR)-targeted agents, targeted DDR inhibitors, including olaparib, are currently rarely evaluated in BTC. In our project, a total of ten BTC cell lines were used to assess the efficacy of olaparib. Olaparib alone showed moderate anti-proliferative effects in BTC cells and increased p-ATR and PD-L1 expression levels. In combination with an ATR inhibitor (AZD6738, ceralasertib) showed synergistic anti-proliferative effects and increased DNA strand breaks in vitro. PD-L1 induced by olaparib was also downregulated by ceralasertib through p-STAT-3 and YAP reduction with or without human primary peripheral blood mononuclear cells. In SNU478-xenograft models, the combination treatment significantly suppressed tumor growth. PD-L1 and YAP were strongly downregulated, similar to in vitro conditions, and expression of CXCR2 and CXCR4 was further reduced. In the current ongoing clinical trial (NCT04298021), BTC patients treated with olaparib and ceralasertib combination have shown tumor response. In conclusion, co-targeting of PARP and ATR might be a potential therapeutic approach for patients with BTC.

To date, many efforts have been made to understand the resistance mechanism of trastuzumab in human epidermal growth factor receptor 2 (HER2)-positive breast and gastric cancer. However, there is still a huge unmet medical need for patients with trastuzumab resistance. In our study, we generated four trastuzumab-resistant (HR) cancer cell lines from ERBB2-amplified gastric and biliary tract cancer cell lines (SNU-216, NCI-N87, SNU-2670, and SNU-2773). Here, we found higher PD-L1 expression in trastuzumab-resistant (HR) HER2-positive cancer cells than in parental cells, and blocking PD-L1 reversed the resistance to trastuzumab in HR cells. Trastuzumab upregulated PD-L1 expression via NF-κB activation in both parental and HR cells, however, led to DNA damage only in parental cells. The WEE1 inhibitor adavosertib, which downregulates PD-L1 expression, enhanced trastuzumab efficacy by blocking BRCA1-CMTM6-PD-L1 signals and the HER2-CDCP-1-SRC axis. Additionally, the levels of galectin-9, CD163, FoxP3, and CTLA-4 were diminished by blocking WEE1 in the presence of human PBMCs in vitro. Taken together, the strategy of co-targeting HER2 and WEE1 could overcome resistance to trastuzumab in HER2-positive cancers, supporting further clinical development in HER2-positive cancer patients.

Background: PARP inhibitors have shown antitumor activities against solid tumors with HRD (homologous recombination deficiency). The definition of HRD and other potential biomarkers besides HRD should be further evaluated for PARP inhibitors. JPI-547 is a novel PARP inhibitor, simultaneously targeting tankyrase1/2, other members of the PARP family, that are involved in the Wnt/β-catenin pathway. Method: Antiproliferative effect of JPI-547 and a variety of PARP inhibitors (olaparib, veliparib, talazoparib, niraparib, and rucaparib) were determined by MTT assay or clonogenic assay in 9 human pancreatic ductal adenocarcinoma (PDAC) cell lines (Capan-1, HPAF-II, Capan-2, AsPC-1, SNU-410, SNU-213, SNU-324, MIA-PaCa2, and PANC-1). Transcriptome data and gene dependency score of the cell lines were obtained from the CCLE database and DepMap respectively. DNA damage was monitored by immunofluorescent imaging of γ-H2AX and DR-GFP assay determined the homologous recombination repair (HRR) efficiency. A xenograft tumor model was established to substantiate the in vivo antitumor effect of JPI-547. Results: JPI-547 more potently blocks Poly(ADP-ribosyl)ation than olaparib, and induces a strong antiproliferative effect on Capan-1, a cell line with BRCA2 del. JPI-547 leads to cell cycle arrest and induces enhanced apoptotic cell death than olaparib. JPI-547 inhibits tumor growth of Capan-1 in vivo, suggesting the potent antitumor activity of JPI-547 against PDAC with HRD. Cell lines harboring RNF43 LOF mutations (HPAF-II, AsPC-1, and Capan-2), intrinsically addicted to Wnt/β-catenin pathway, are more sensitive to JPI-547 than cells with RNF43 wild types. Interestingly, RNF43 mutations could not distinguish the sensitivity of other PARP inhibitors except JPI-547. CTNNB1 gene dependency score and β-catenin levels positively correlate with cellular sensitivity to JPI-547. JPI-547-induced DNA damage was alleviated in HR-proficient PDAC cells. DR-GFP assays confirm that JPI-547 does not directly alter the HRR efficiency of Wnt-addicted PDAC cells. Collectively, these data indicate that the vulnerabilities of Wnt-addicted PDAC cells to JPI-547 were irrelevant to HRD mimicking. Rather, JPI-547 stabilizes AXIN-2 in Wnt-addicted PDAC cells and downregulates the active form of β-catenin level in the nucleus, thereby disrupting the transcription of its target genes. Knockdown of β-catenin neutralized the antiproliferative effect of JPI-547, suggesting that inhibition of the β-catenin pathway is an important mode of action by JPI-547 in Wnt-addicted PDAC cells. Conclusion: JPI-547 shows promising, preclinical antitumor effects against PDAC cells with HRD or Wnt-addiction, providing a rationale for further biomarker-driven clinical development of JPI-547 for the treatment of patients with PDAC. Citation Format: Kyoung-Seok Oh, Ah-Rong Nam, Ju-Hee Bang, Yoojin Jeong, Sea Young Choo, Hyo Jung Kim, Su In Lee, Jae-Min Kim, Jeesun Yoon, Tae-Yong Kim, Banyoon Cheon, Hyunju Cha, John Kim, Do-Youn Oh. JPI-547, a dual inhibitor of PARP/Tankyrase, shows promising antitumor activity against pancreatic cancers with homologous recombination repair deficiency or Wnt-addiction. [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 4496.

Background: HER2 (Human epithelial growth factor receptor 2)-targeting therapies have been approved for patients with HER2-positive breast and gastric cancer and use have been attempted in various solid tumor types, including biliary tract cancer. However, resistance mechanism remains as a major challenge of HER2-targeting therapies. YAP (Yes-associated protein) is a major downstream effector of Hippo pathway, and it plays an essential role in cancer cell proliferation, survival and differentiation. Moreover, YAP is emerging as a key player of resistance mechanism of cytotoxic and targeted drugs. Yap is also an important immunosuppressive molecule as it works as a negative regulator of T cell tumor infiltration. In this study, we intend to elucidate the role of YAP in mechanism of trastuzumab resistance and T cell immune response in HER2-positive cancer cells. Methods: We established four trastuzumab-resistant (HR) cell lines (N87HR, SNU216HR, SNU2670HR and SNU2773HR) from HER2-postive gastric and biliary tract cancer cell lines. To inhibit the function of YAP, siRNA and Verteporfin (YAP-TEAD inhibitor) were used. MTT assay, cell cycle analysis, western blot and migration assay were performed to analyze the antitumor effects through YAP downregulation. In order to evaluate immune-modulation by YAP, human PBMC co-culture was used and immune markers were analyzed by RT-PCR and flow cytometry. Mouse xenograft models were established using SNU2773 and SNU2773HR cells. Results: We confirmed that the expressions of pYAP and YAP were elevated in HR cells (SNU216HR, SNU2670HR and SNU2773HR) compared to parental cells. Reducing the expressed YAP in HR cells inhibited tumor cell growth and migration and induced apoptosis. Immune suppression markers such as PD-L1, CD155, and galectin-9 were effectively decreased, while CD80, a stimulation marker, was increased by verteporfin treatment. Also, when YAP was decreased, CCL5 and CXCL10, well known CD8+ T cell recruitment cytokines, were increased. In HR cells treated with siYAP and verteporfin, there was a trend of increasing CD4+ and CD8+ T cells when co-culture with PBMC. In vivo experiment data showed greater tumor growth inhibition effects with SNU2773HR than SNU2773 xenograft models when treated with verteporfin. Conclusion: The expression of YAP is elevated in trastuzumab-resistant (HR) cells and inhibition of YAP shows anti-tumor effects and activation of T cell responses. Collectively, our data suggests that the inhibition of YAP is one of many promising strategies to overcome trastuzumab resistance and T cell regulatory mechanisms in HER2-positive cancers. Citation Format: Ah Rong Nam, Jeesun Yoon, Kyoung-Seok Oh, Jae-Min Kim, Ju-Hee Bang, Yoojin Jeong, Sea Young Choo, Hyo Jung Kim, Su In Lee, Tae-Yong Kim, Do-Youn Oh. Targeting of YAP overcomes trastuzumab-resistance and promotes immune responses in HER2-positive cancers. [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 3872.

Background Germline mutations of breast cancer susceptibility gene BRCA1 and BRCA2 (gBRCA1/2) are associated with elevated risk of breast cancer in young women in Asia. BRCA1 and BRCA2 proteins contribute to genomic stability through homologous recombination (HR)-mediated double strand DNA break repair (DDR) in cooperation with other HR-related proteins. In this study, we analyzed the targeted sequencing data of the breast cancer patients with gBRCA1/2 mutations to investigate the landscape of HR-related gene mutations and their clinical implications. Materials and Methods Data of the breast cancer patients with pathogenic gBRCA1/2 mutations and qualified targeted next generation sequencing, SNUH FiRST cancer panel, were analyzed. Single nucleotide polymorphisms, small insertions and deletions were analyzed with functional annotations using ANNOVAR. HR-related genes were defined as ABL1, ATM, ATR, BARD1, BRCA1, BRCA2, CDKN1A, CDKN2A, CHEK1, CHEK2, FANCA, FANCD2, FANCG, FANCI, FANCL, KDR, MUTYH, PALB2, POLE, POLQ, RAD50, RAD51, RAD51D, RAD54L, and TP53. Mismatch-repair genes were MLH1, MSH2, and MSH6. Clinical data were analyzed with cox proportional hazard models and survival analyses. Results Fifty five Korean breast cancer patients with known gBRCA1/2 mutations and qualified targeted NGS data were analyzed. Ethnically distinct mutations in gBRCA1/2 genes were noted, with higher frequencies of Val1833Ser (14.8%), Glu1210Arg (11.1%), and Tyr130Ter (11.1%) in gBRCA1 and Arg2494Ter (25.0%) and Lys467Ter (14.3%) in gBRCA2. Considering subtypes, gBRCA1 mutations were associated with triple-negative breast cancers (TNBC), while gBRCA2 mutations were more likely hormone receptor-positive breast cancers. At least one missense mutation of homologous recombination (HR)-related genes were observed in 44 cases (80.0%). The most frequently co-mutated gene was TP53 (38.1%). In patients with gBRCA1/2 mutations, however, genetic variations of TP53 occurred in locations different from the known hotspots of those with sporadic breast cancers. The patients with both gBRCA1/2 and TP53 mutations were more likely to have TNBC, high Ki-67 values, and increased genetic mutations, especially of HR-related genes. Survival benefit was observed in the TP53 mutants of patients with gBRCA2 mutations, compared to those with TP53 wildtypes. Conclusion Our study showed distinct genetic landscape of breast cancer patients with gBRCA1 and gBRCA2 mutations in the Asian populations. Further studies on precision medicine are needed for tailored treatments of patients with genetic diversity among different ethnic groups. Citation Format: Jinyong Kim, Kyeonghun Jeong, Hyeji Jun, Kwangsoo Kim, Tae-Yong Kim, Dae-Won Lee, Go-un Woo, Songyi Park, Hanbaek Yi, Kyung-Hun Lee, Seock-Ah Im. Mutations of TP53 and genes related to homologous recombination repair in breast cancer with germline BRCA1/2 mutations [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-03-20.

Purpose This study investigated the association of insulin, metformin, and statin use with survival and whether the association was modified by the hormone receptor status of the tumor in patients with breast cancer.Materials and Methods We studied 7,452 patients who had undergone surgery for breast cancer at Seoul National University Hospital from 2008 to 2015 using the nationwide claims database. Exposure was defined as a recorded prescription of each drug within 12 months before the diagnosis of breast cancer.Results Patients with prior insulin or statin use were more likely to be older than 50 years at diagnosis and had a higher comorbidity index than those without it (p < 0.01 for both). The hazard ratio (HR) for death with insulin use was 5.7 (p < 0.01), and the effect was attenuated with both insulin and metformin exposure with an HR of 1.2 (p=0.60). In the subgroup analyses, a heightened risk of death with insulin was further prominent with an HR of 17.9 (p < 0.01) and was offset by co-administration of metformin with an HR of 1.3 (p=0.67) in patients with estrogen receptor (ER)–negative breast cancer. Statin use was associated with increased overall mortality only in patients with ER-positive breast cancer with HR for death of 1.5 (p=0.05).Conclusion Insulin or statin use before the diagnosis of breast cancer was associated with an increase in all-cause mortality. Subsequent analyses suggested that metformin or statin use may have been protective in patients with ER-negative disease, which warrants further studies.

Although metabolic intratumoral heterogeneity (ITH) gives important value on treatment responses and prognoses, its association with treatment outcomes have not been reported in gastric cancer (GC). We aimed to evaluate temporal changes in metabolic ITH and the associations with treatment responses, progression-free survival (PFS), and overall survival (OS) in advanced GC patients. Eighty-five patients with unresectable, locally advanced, or metastatic GC were prospectively enrolled before the first-line palliative chemotherapy and underwent [18F]FDG PET at baseline (TP1) and the first response follow-up evaluation (TP2). Standardized uptake values (SUVs), volumetric parameters, and textural features were evaluated in primary gastric tumor at TP1 and TP2. Of 85 patients, 44 had partial response, 33 had stable disease, and 8 progressed. From TP1 to TP2, metabolic ITH was significantly reduced (P P max at TP2, a high kurtosis at TP2 and larger decreases in the coefficient of variance were associated with better PFS. A low SUVmax at TP2, larger decreases in the metabolic tumor volume and larger decreased in the energy were associated with better OS. Age older than 60 years and responders also showed better OS. An early reduction in metabolic ITH is useful to predict treatment outcomes in advanced GC patients.

Breast cancer patients often develop musculoskeletal pain, resembling that experienced by patients with rheumatoid arthritis (RA), during cancer treatment. This study aimed to investigate the causes of musculoskeletal pain, including RA, among breast cancer patients.This retrospective study included breast cancer patients experiencing new-onset arthralgia during cancer treatment along with age- and sex-matched controls without breast cancer, who were evaluated at the Rheumatologic clinic between 2004 and 2017. The causes of musculoskeletal pain were compared between breast cancer patients and controls. The effects of cancer treatment on arthralgia and factors associated with RA were examined.A total of 146 breast cancer patients and 102 controls were included in the final analysis. The most common cause of arthralgia during breast cancer treatment was osteoarthritis (OA, 61.0%), followed by enthesopathy/tendinopathy (28.1%), which included tendinitis, adhesive capsulitis, and carpal tunnel syndrome. Overall, 50.0% of 72 breast cancer patients receiving aromatase inhibitors (AIs) satisfied the criteria of AI-induced musculoskeletal symptoms (AIMSS). The mean symptom duration (i.e., the time between pain onset and evaluation by a rheumatologist) was shorter in breast cancer patients than in controls (7.0 ± 12.1 vs. 14.8 ± 24.9 months, respectively;OA and enthesopathy/tendinopathy are the most common causes of arthralgia in breast cancer patients, which may concurrently manifest as AIMSS. Patients with breast cancer did not have a higher prevalence of RA than those without breast cancer.

Dabrafenib is a BRAF kinase inhibitor approved for treatment of BRAF-mutated anaplastic thyroid carcinoma (ATC) in combination with trametinib. Erlotinib is a tyrosine kinase inhibitor of EGF receptor (EGFR). We evaluated effects of dabrafenib and erlotinib combination treatment on ATC cells in vitro and in vivo. Cell proliferation, colony formation, apoptosis, and migration of ATC cells harboring a BRAF mutation (BHT101, 8505C, and SW1736) were evaluated after treatment with dabrafenib in combination with erlotinib or trametinib. The changes in activation of mitogen extracellular kinase (MEK) and extracellular signal-related kinase (ERK) signaling were also evaluated by Western blot analysis. Effects of these combinations were also evaluated using an in vivo xenograft model. First, we detected EGFR activation in dabrafenib-resistant SW1736 cells using a phospho-receptor tyrosine kinase array. A dabrafenib and erlotinib combination synergistically inhibited cell proliferation, colony formation, and migration, with an induction of apoptotic cell death in all three ATC cells, compared with dabrafenib or erlotinib alone. This synergistic effect was comparable with a dabrafenib and trametinib combination. The dabrafenib and erlotinib combination effectively inhibited phosphorylated (p)-MEK, p-ERK, and p-EGFR expressions compared with dabrafenib or erlotinib alone, while the dabrafenib and trametinib combination only inhibited p-MEK and p-ERK expressions. The dabrafenib with erlotinib or trametinib combinations also significantly suppressed tumor growth and induced apoptosis in a BHT101 xenograft model. The dabrafenib and erlotinib combination could be a potential novel treatment regimen to overcome drug resistance to dabrafenib alone in patients with BRAF-mutated ATC.

Background Vandetanib is the most widely used tyrosine kinase inhibitor for the treatment of patients with advanced medullary thyroid cancer (MTC). However, only limited data regarding its use outside clinical trials are available. We aimed to evaluate the efficacy and safety of vandetanib in patients with advanced MTC in routine clinical practice. Methods In this multicenter retrospective study, 12 patients with locally advanced or metastatic MTC treated with vandetanib at four tertiary hospitals were included. The primary outcome was the objective response rate (ORR) based on the Response Evaluation Criteria in Solid Tumors. The progression-free survival (PFS), overall survival (OS), and toxicities were also evaluated. Results Eleven patients (92%) had distant metastasis and 10 (83%) had disease progression at enrollment. Partial response was observed in five patients (ORR, 42%) and stable disease lasting ≥24 weeks was reported in an additional five patients (83%). During the median 31.7 months of follow-up, disease progression was seen in five patients (42%); of these, two died due to disease progression. The median PFS was 25.9 months, while the median OS was not reached. All patients experienced adverse events (AEs) which were generally consistent with the known safety profile of vandetanib. Vandetanib was discontinued in two patients due to skin toxicity. Conclusion Consistent with the phase III trial, this study confirmed the efficacy of vandetanib for advanced MTC in terms of both ORR and PFS in the real-world setting. Vandetanib was well tolerated in the majority of patients, and there were no fatal AEs.

This study compared the tumor immune microenvironments (TIMEs) of primary gastric cancer (PGC) and paired metastatic gastric cancer (MGC). CD4+ and CD8+ T-cell density and PD-L1 expression were evaluated by multiplex immunohistochemistry, DNA mismatch repair (MMR) by immunohistochemistry, and immune-related genes by RNA sequencing. Twenty-three patients who underwent surgical treatment for PGC and MGC were enrolled in this study. CD8+ T-cell, PD-L1+ cell, and PD-L1+CK+ cell densities were significantly lower in MGC than PGC. PD-L1 positivity using a combined positive score (≥ 1%) and deficient MMR were observed in 52.2% and 8.7% of PGC samples, respectively, whereas both occurred in only 4.3% of MGC samples. The most frequent TIME types were inflamed (34.8%) and adaptive immune resistance (34.8%) in PGC, and immune desert (65.2%) and immunological ignorance (73.9%) in MGC. In transcriptome analysis, the expression of the T-cell inflamed gene set and co-stimulatory gene module was down-regulated in MGC compared to PGC. The total CD8+ T-cell density was an independent prognostic marker in both PGC and MGC (univariate P = 0.002, multivariate P = 0.006). Our result suggest that the TIME of metastatic tumors was less immunologically active compared to that of primary tumors in gastric cancer patients.

Current diagnosis of bone metastasis (BM) in breast cancer relies on structural changes of bone that occur only in the advanced stage. A sensitive biomarker for detecting early progression of bone metastasis is urgently required. We performed clinical and preclinical studies to investigate diagnostic value of circulating osteocalcin-positive cells (cOC) in breast cancer bone metastasis. Metastatic breast cancer patients (n = 92) with or without bone metastasis (ie, BM+ or BM- ) were enrolled, and cOC were measured at enrollment. Patients were followed up for bone metastasis progression for 18 months. BM+ patients (n = 59) were divided into progressive (PD) or stable disease (SD) groups, based on imaging studies at the end of the 18-month study. The PD group had higher baseline cOC compared with the SD group. Furthermore, higher cOC resulted in reduced BM progression-free survival. Three patients in the BM- group (n = 33) developed new BM during the 18-month study, and these patients had a higher level of baseline cOC compared with the remaining BM- patients. In murine preclinical studies, cOC increased at early time points when micro-metastases were evident only by histology but undetectable by bioluminescence imaging. Also, cOC levels predicted the progression of BM and correlated significantly with BM tumor burden. cOC increased in the early phase of breast cancer BM and can predict BM progression, supporting cOC as a potential novel biomarker. © 2020 American Society for Bone and Mineral Research.

Accurate prediction of pathologic complete response (pCR) in breast cancer using magnetic resonance imaging (MRI) and ultrasound (US)-guided biopsy may aid in selecting patients who forego surgery for breast cancer. We evaluated the accuracy of US-guided biopsy aided by MRI in predicting pCR in the breast after neoadjuvant chemotherapy (NAC). After completion of NAC, 40 patients with near pCR (either tumor size ≤ 0.5 cm or lesion-to-background signal enhancement ratio (L-to-B SER) ≤ 1.6 on MRI) and no diffused residual microcalcifications were prospectively enrolled at a single institution. US-guided multiple core needle biopsy (CNB) or vacuum-assisted biopsy (VAB) of the tumor bed, followed by standard surgical excision, was performed. Matched biopsy and surgical specimens were compared to assess pCR. The negative predictive value (NPV), accuracy, and false-negative rate (FNR) were analyzed. pCR was confirmed in 27 (67.5%) surgical specimens. Preoperative biopsy had an NPV, accuracy, and FNR of 87.1%, 90.0%, and 30.8%, respectively. NPV for hormone receptor-negative and hormone receptor-positive tumors were 83.3% and 100%, respectively. Obtaining at least 5 biopsy cores based on tumor size ≤ 0.5 cm and an L-to-B SER of ≤ 1.6 on MRI (27 patients) resulted in 100% NPV and accuracy. No differences in accuracy were noted between CNB and VAB (90% vs. 90%). Investigation using stringent MRI criteria and ultrasound-guided biopsy could accurately predict patients with pCR after NAC. A larger prospective clinical trial evaluating the clinical safety of breast surgery omission after NAC in selected patients will be conducted based on these findings.

Major clinical challenges exist with differentiated thyroid cancers with distant metastases or rare but aggressive types, such as poorly differentiated thyroid carcinomas and anaplastic thyroid carcinomas. The precise characterization of the mutational profile in these advanced thyroid cancers is crucial. Samples were collected from primary tumors and distant metastases of 64 patients with distant metastases from differentiated thyroid cancer, poorly differentiated thyroid carcinoma, or anaplastic thyroid carcinoma. Targeted next-generation sequencing was performed with 50 known thyroid-cancer-related genes. Of the 82 tissues, 63 were from primary tumors and 19 from distant metastases. The most prevalent mutation observed from the primary tumors was TERT promoter mutation (56%), followed by BRAF (41%) and RAS (24%) mutations. TP3 was altered by 11%. Mutations in histone methyltransferases, SWI/SNF subunit–related genes, and PI3K/AKT/mTOR pathway-related genes were present in 42%, 12%, and 22%, respectively. When the mutational status was analyzed in 15 matched pairs of thyroid tumors and their matched distant metastases and one pair of distant metastases with two distinct sites, the concordance was high. A similar frequency of mutations in TERT promoter (58%) and BRAF (42%) as well as histone methyltransferases (37%), SWI/SNF subunits (10%), and PI3K/AKT/mTOR pathway (26%) were noted. The same main, early and late mutations were practically always present in individual primary tumor–metastasis pairs. Enrichment of TERT promoter, BRAF, and RAS mutations were detected in highly advanced thyroid cancers with distant metastasis. The genetic profiles of primary thyroid tumors and their corresponding distant metastases showed a high concordance.

In view of the planned new edition of the most recent version of the European Society for Medical Oncology (ESMO) Clinical Practice Guidelines for the diagnosis, treatment and follow-up of primary breast cancer published in 2015, it was decided at the ESMO Asia Meeting in November 2018, by both the ESMO and the Korean Society of Medical Oncology (KSMO), to convene a special face-to-face guidelines meeting in 2019 in Seoul. The aim was to adapt the latest ESMO 2019 guidelines to take into account the ethnic and geographical differences associated with the treatment of early breast cancer in Asian patients. These guidelines represent the consensus opinions reached by experts in the treatment of patients with early breast cancer representing the oncology societies of Korea (KSMO), China (CSCO), India (ISMPO) Japan (JSMO), Malaysia (MOS), Singapore (SSO) and Taiwan (TOS). The voting was based on scientific evidence, and was independent of both the current treatment practices, and the drug availability and reimbursement situations, in the individual participating Asian countries.

Purpose: Diagnosis of bone metastasis (BM) in breast cancer relies on structural changes of bone. We investigated whether circulating osteocalcin-positivecells (cOC) could detect the incipient and/or progressive BM earlier than image-based diagnostics. Experimental design: Metastatic breast cancer patients with or without bone metastasis (designated BM+ or BM-) were enrolled and cOC were quantified at baseline by flow cytometry. The progression of BM was evaluated after 18 months. Murine BM models were established by intra-tibial or -cardiac injection of MDA-MB-231 or 4T1 breast cancer cells. Results: In the baseline analysis, cOC was significantly higher in BM+ than BM- group. In the 18-month follow-up study of BM+ patients (n=63), baseline cOC was significantly associated with BM disease progression. Among BM- patients (n=33), three patients developed new bone metastasis within 18 months and were found to have had higher cOC at baseline. The patients with higher cOC showed shortened BM progression-free survival, compared with those with lower cOC (cutoff=0.045%; P Conclusions: cOC is increased in the early phase of breast cancer BM and predict the disease progression. cOC can be a novel biomarker for early diagnosis and progression of BM. Citation Format: Sun Wook W Cho, Kyung-Hun Lee, Tae-Yong Kim, Serk In Park, Seock-Ah Im. Circulating osteocalcin-positive cells as a novel diagnostic biomarker for bone metastasis in breast cancer patients [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-19-02.

Using a parallel-process latent growth model (LGM), this study examined whether posttraumatic stress symptoms (PTSS) are associated with the trajectory of sleep disturbance (SD) and fatigue and whether the SD trajectory mediates the PTSS-fatigue relationship.Data were from 215 patients with breast cancer recruited from a tertiary hospital in South Korea. A self-report survey was administered at four time points during the course of adjuvant chemotherapy.The mean age of the participants was 46.69 (SD = 9.08) and the majority was at stage I and the average months since diagnosis was 1.33 (SD = 1.43). Unconditional parallel-process LGM indicated that SD and fatigue were positively associated with each other, both in terms of initial status and growth rate. Then, the conditional parallel-process LGM with baseline PTSS (i.e., avoidance, intrusion, and hyperarousal) as predictors were examined and anxiety, depressive symptoms and chronotype were entered as covariates in the model. Results indicated that a higher initial status and faster growth of SD were associated with a faster increase in fatigue. Greater baseline hyperarousal was directly related to a higher initial status and a slower increase in SD, and higher initial fatigue. Furthermore, a higher hyperarousal was associated with a greater initial SD, which was related to a faster increase in fatigue. Additionally, the late chronotype was related to a faster increase in fatigue through its impact on the initial SD.The detrimental impact of hyperarousal on the SD trajectory and fatigue suggests the need to intervene in PTSS and SD early and throughout the course of cancer treatments to prevent fatigue.

We previously reported that high thyroid-stimulating hormone (TSH) levels are associated with papillary thyroid microcarcinoma (PTMC) progression during active surveillance. However, validation with multicenter, long-term data, and identification of appropriate age or TSH levels are needed. This multicenter retrospective study enrolled PTMC patients under active surveillance with TSH measurements and ultrasonography. The primary outcome was PTMC progression (volume increase ≥50%, size increase ≥3 mm, or new lymph node (LN) metastasis). PTMC progression according to time-weighted average of TSH (TW-TSH) groups was compared using survival analyses in overall patients and each age subgroups (P = 0.006), but the impact was significant only in patients aged P = 0.004), 2.55 (1.00–6.47; P = 0.049)). For patients aged P for trend = 0.034). In young PTMC patients (

456 Background: Tumor consists of not only cancer cells but also various immune cells or stromal cells. And tumor microenvironment (TME) is known to be associated with response and resistance to treatment. However, the role of TME in the response to chemotherapy in advanced gastric cancer (AGC) remains unclear. We evaluated whether TME can affect the survival in patients with AGC who received first-line chemotherapy using high plex digital spatial profiling (DSP). Methods: Patients with AGC who received first-line chemotherapy were registered. Archival tumor tissue before first-line chemotherapy were obtained and tissue microarrays (TMAs) were made. Regions of interest (ROIs) were selected on each TMA and high plex DSP including RNA transcript was performed in all ROIs using GeoMx DSP (Whole Transcriptome Atlas) after masking by cytokeratin (CK) immunofluorescence. Differentially expressed gene (DEG), geneset enrichment analysis (GSEA), gene ontology (GO) and cell subsets were analyzed separately in CK-positive and CK-negative areas, using EdgeR, mSigDb, DAVID and CIBERSORT. Results: Thirty-three tumor tissues from 33 patients and 5 normal tissues were analyzed. All patients received fluoropyrimidine and platinum doublet chemotherapy. HER2+ was 15.2% and all with HER2+ AGC received trastuzumab plus chemotherapy. Five received nivolumab plus chemotherapy. Response rate was 48.5% and progression-free survival (PFS) was 9.8 months (95% CI, 6.85-NA). In CK-positive area, high expression of PIGR (polymeric Immunoglobulin receptor gene) (FDR q=0.013) and low expression of IFNE (FDR q=0.027) were associated with long PFS. Response to interferon beta (FDR q=0.044), cytokine-cytokine receptor interaction (FDR q=0.014) and antigen processing and presentation pathway (FDR q=0.015) were less activated in patients with long PFS in GO and GSEA. Although the density of CD8+ T cell did not affect PFS (6.9 vs. 10.8, p=0.25), high density of CX3CR1+memory CD8+T cells (Tmem) showed longer PFS (18.3 vs. 6.6 months, p=0.01), compared with low density of CX3CR1+CD8+Tmem. In CK-negative area, low density of CD8+ T cells were associated with longer PFS (6.3 vs. 18.3 months, p= 0.008). Conclusions: TME particularly in CK-positive area might affect survival for chemotherapy in AGC. PIGR and CX3CR1+CD8+Tmem were suggested as good candidate markers for predicting clinical outcomes of chemotherapy, indicating further analysis of TME will be needed especially in patients with AGC who received immune checkpoint inhibitors.

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.

404 Background: DNA damage response (DDR) gene alterations are observed in 27% of gastric cancer (GC), therefore, targeting DDR might be an interesting strategy in GC. Olaparib plus paclitaxel showed numerically improved overall survival (OS) compared to paclitaxel in 2L GC patients (pts), even though it did not meet the endpoint. (Lancet Oncol 2017). Besides DNA damage repair, olaparib induces immune modulation. The role of immune checkpoint inhibitor (ICI) is established in 1L and 3L+ GC. The combination of cytotoxic chemotherapy, DDR acting agent and ICI might have synergistic effects in GC, which has not been tested in clinical studies. Here, we report biomarker-oriented phase II study of paclitaxel/olaparib/durvalumab combination in 2L GC. (NCT03579784). Methods: Advanced GC pts who have failed to 1L chemotherapy were enrolled. During 1st cycle, paclitaxel (80 mg/m2, D1, 8, 15 Q 4wk) and olaparib (150mg bid, D1-28) was administered. From 2nd cycle, durvalumab (1500 mg, D1 Q 4wk) was added on them. Tumor biopsy (pretreatment, after 1st cycle, at disease progression) and blood collection (every cycle) was mandatory. Primary endpoint was the disease control rate (DCR). Secondary endpoints included ORR, DoR, PFS, OS and safety. For biomarker study, multiplex IHC, NGS, ctDNA, and cytokines and angiogenic factors analysis were performed. Efficacy analysis set (ES) and safety analysis set (SS) were defined as pts who underwent at least one tumor assessment and all pts who received cycle1 day1 or more, respectively. Results: Fifty pts were enrolled (6 screening fail or withdrawal of consent, 44 in SS, 38 in ES) HER2+ GC were 13.2%. Among 38 in ES, DCR and ORR were 84.1% (95% CI, 72.5-95.7) and 39.5% (95% CI, 24.0-55.0) (1 CR, 14 PR and 17 SD). PFS, DoR and OS were 6.7 (95% CI, 4.5-10.3), 6.5 (95% CI, 5.1-10.7) and 11.4 (95% CI, 9.2-13.2) months. Homologous recombination repair (HRR) genetic alterations (9.6 vs. 5.9 in PFS, p=0.037), high CD8/CD3 ratio (8.8 vs. 3.7 in PFS, p=0.008), high PD-L1 (CPS≥10) (9.6 vs 5.1 in PFS, p=0.031), low ATM IHC (13.3 vs. 9.8 in OS, p=0.066), and low serum IL-6 (12.9 vs. 8.3 in OS, p=0.001) were associated with prolonged PFS or OS. In SS, most adverse events (AEs) were mild, and Gr 3/4 leukopenia and anemia were observed in 52.2% and 31.8%. There were no treatment related AEs resulted in study discontinuation. Conclusions: Paclitaxel/olaparib/durvalumab is a promising combination in 2L GC, and is worth to be further explored, especially in biomarker-enriched patients with HRR, specific T-cells subsets, high PD-L1, low ATM and IL-6. Clinical trial information: NCT03579784 .

The purpose of this longitudinal prospective cohort study was to investigate the role of chronotype in the incidence of chemotherapy-induced peripheral neuropathy (CIPN) among women with breast cancer. A total of 128 subjects with breast cancer awaiting adjuvant chemotherapy without peripheral neuropathy participated in this study. The presence of CIPN was defined as a response of 3 or higher on a peripheral neuropathy subscale in the MD Anderson Symptom Inventory. Candidate psychiatric factors associated with CIPN were assessed, using the Composite Scale of Morningness, the Pittsburgh Sleep Quality Index, and the Hospital Anxiety and Depression Scale. To examine the association between chronotype and CIPN, we built logistic regression models, adjusting for demographic, clinical, and other psychiatric variables. Forty-nine participants received a chemotherapy regimen containing docetaxel, of which 29 (59%) developed CIPN. We performed subgroup analyses of docetaxel-treated participants. The morning chronotype was inversely associated with CIPN (odds ratio, 0.07; confidence interval, 0.01–0.48; p = 0.016) after adjusting for age, BMI, education, alcohol use, smoking, disease stage, sleep quality, depression, and anxiety. Our results suggest that the morning chronotype is a protective factor against the development of CIPN in patients with breast cancer who were treated with docetaxel.

Objective Patients with breast cancer receiving neoadjuvant chemotherapy are at increased risk of poor health-related quality of life (HRQOL). This study examined clinical caseness on depression and anxiety mediate the relationship between resilience and HRQOL in patients with breast cancer. Methods A total of 193 patients with breast cancer undergoing neoadjuvant chemotherapy completed questionnaires including the Connor-Davidson Resilience Scale, Hospital Anxiety and Depression Scale (HADS), and Functional Assessment of Cancer Therapy-Breast before the first session (T0), before the start of the last session (T1), and 6 months after the end (T2) of chemotherapy. Mediation analyses using a bootstrapping method was performed. Results The indirect effect (IE) through T1 depression was significant (IE through depression = 0.043, 95% confidence interval [CI] [0.002-0.090]), while IE through T1 anxiety was not significant (IE through anxiety = 0.037, 95% CI [-0.010-0.097]) in the association between T0 resilience and T2 HRQOL. Conclusions Clinical caseness on HADS depression subscale during chemotherapy was a mediating factor of the relationship between resilience before chemotherapy and HRQOL after chemotherapy in patients with breast cancer receiving neoadjuvant chemotherapy. Depression during chemotherapy in patients with breast cancer may be a target symptom of screening and intervention to maintain the HRQOL after chemotherapy. Also, patients with low resilience are more likely to develop depression during chemotherapy, and clinicians should carefully monitor whether depression occurs in these patients with low resilience.

Gastric cancer (GC) is commonly treated by chemotherapy using 5-fluorouracil (5-FU) derivatives and platinum combination, but predictive biomarker remains lacking. We develop patient-derived xenografts (PDXs) from 31 GC patients and treat with a combination of 5-FU and oxaliplatin, to determine biomarkers associated with responsiveness. When the PDXs are defined as either responders or non-responders according to tumor volume change after treatment, the responsiveness of PDXs is significantly consistent with the respective clinical outcomes of the patients. An integrative genomic and transcriptomic analysis of PDXs reveals that pathways associated with cell-to-cell and cell-to-extracellular matrix interactions enriched among the non-responders in both cancer cells and the tumor microenvironment (TME). We develop a 30-gene prediction model to determine the responsiveness to 5-FU and oxaliplatin-based chemotherapy and confirm the significant poor survival outcomes among cases classified as non-responder-like in three independent GC cohorts. Our study may inform clinical decision-making when designing treatment strategies., Gastric cancer is commonly treated by chemotherapy using 5-fluorouracil derivatives and platinum combination, but predictive biomarker remains lacking. Here, the authors develop a 30-gene prediction model to determine the responsiveness to 5-fluorouracil and oxaliplatin-based chemotherapy through the integrative profiling of patient-derived xenografts

Background/Aims: Palbociclib is a cyclin dependent kinase 4 and 6 inhibitor which shows promising effect in hormone receptor positive breast cancer. The purpose of this study is to evaluate the real-world efficacy and toxicity of palbociclib plus endocrine therapy. Methods: This is a retrospective study performed in two tertiary referral hospitals in Korea. Advanced breast cancer patients who were treated with 1st line palbociclib plus endocrine therapy were enrolled.Results: A total of 216 patients were included between August 2016 and May 2019. Median age was 56 (29-89) years old and 75 patients (34.7%) were premenopausal. Median progression-free survival (PFS) was 33.0 months (95% confidence interval [CI] 24.7 to 41.3) and objective response rate was 59.3%. Luminal B patients had shorter PFS (Not reached vs. 33.0 months, p = 0.019) and tendency of lower ORR (58.3 vs. 62.0%, p = 0.19) compared to luminal A patients. Multivariate analysis revealed luminal B (adjusted hazard ratio 1.90, p = 0.038) and germline BRCA mutation (adjusted hazard ratio 5.57, p = 0.002) as an independent poor prognostic factor for PFS. The most common grade 3 or 4 adverse event was neutropenia (86.7%).Conclusions: The efficacy and toxicity of palbociclib in the real-world was comparable to those of clinical trials. In addition, palbociclib with endocrine therapy was an effective treatment option for young patients. Luminal B and germline BRCA mutation was associated with inferior outcome.

OBJECTIVE Evidence for American Thyroid Association (ATA) risk stratification stems largely from studies involving patients undergoing total thyroidectomy. We aimed to assess the risk of recurrence according to the present ATA risk stratification system in patients who underwent lobectomy. DESIGN Retrospective cohort study. PATIENTS Patients who underwent thyroid lobectomy for 1-4 cm-sized papillary thyroid carcinoma (n = 571). MEASUREMENTS Disease-free survival (DFS) was compared according to the ATA risk stratification, and specific lymph node (LN) characteristics were evaluated to modify the ATA criteria with a higher predictability for recurrence. RESULTS Based on the ATA risk stratification, 439 patients (61.1%) were classified into intermediate- or high-risk group, and consideration for completion thyroidectomy is suggested by ATA guidelines for these patients. However, no significant differences were found in DFS among the low-, intermediate- and high-risk groups (P = .9). In contrast, when patients were stratified according solely to the LN criteria from the ATA risk stratification, only 127 patients (22.2%) had intermediate risk (intermediate-N1a) and exhibited significantly poorer DFS than those with N0 disease (P = .035). Modifying the intermediate-N1a criteria by adding the extranodal extension (ENE) status and omitting the clinical nodal disease enabled the subclassification of 19 patients (3%) with a high risk for recurrence. CONCLUSIONS The present study suggests that risk stratification based solely on LN metastases is more reasonable for predicting structural persistence/recurrence following lobectomy than that based on the overall ATA criteria. Considering the ENE status can assist in selecting patients with a high risk of recurrence to minimize further treatments.

Purpose The purpose of this study was to prospectively validate the Korean Cancer Study Group Geriatric Score (KG)-7, a novel geriatric screening tool, in older patients with advanced cancer planned to undergo first-line palliative chemotherapy. Materials and methods Participants answered the KG-7 questionnaire before undergoing geriatric assessment (GA) and first-line palliative chemotherapy. The performance of KG-7 was evaluated by calculating the sensitivity (SE), specificity (SP), positive and negative predictive value (PPV and NPV), balanced accuracy (BA), and area under the curve (AUC). Results The baseline GA and KG-7 results were collected from 301 patients. The median age was 75 years (range, 70 to 93 years). Abnormal GA was documented in 222 patients (73.8%). Based on the ≤ 5 cut-off value of KG-7 for abnormal GA, abnormal KG-7 score was shown in 200 patients (66.4%). KG-7 showed SE, SP, PPV, NPV, and BA of 75.7%, 59.7%, 84.4%, 46.0%, and 67.7%, respectively; AUC was 0.745 (95% confidence interval, 0.687 to 0.803). Furthermore, patients with higher KG-7 scores showed significantly longer survival (p=0.006). Conclusion KG-7 appears to be adequate in identifying patients with abnormal GA prospectively. Hence, KG-7 can be a useful screening tool for Asian countries with limited resources and high patient volume.

Background Pregnancy concurrent with, shortly before, or after breast cancer poses unique challenges because hormonal changes in pregnancy potentially interact with breast cancer outcomes. Materials and Methods We studied a cohort of 3,687 female patients of reproductive age ( Results Forty-five patients with postpartum breast cancer were significantly more likely to have advanced stage, hormone receptor-negative tumor and to be younger than 35 years at diagnosis than those without postpartum breast cancer. This trend was not observed with 18 patients with breast cancer during pregnancy. The unadjusted 5-year survival rates were 77% versus 96% for patients with postpartum breast cancer versus their counterparts, 89% versus 96% for patients with breast cancer during pregnancy versus their counterparts, and 98% versus 96% for patients with pregnancy after breast cancer versus their counterparts, respectively. In the multivariable analyses, postpartum breast cancer exhibited hazard ratios for death of 1.57 (95% confidence interval [CI], 0.82–2.99), whereas those for breast cancer during pregnancy and pregnancy after breast cancer were 1.09 (95% CI, 0.15–7.91) and 0.86 (95% CI, 0.26–2.83), respectively. Conclusion Postpartum breast cancer, but not breast cancer during pregnancy, was associated with advanced stage, younger age at diagnosis ( Implications for Practice Although pregnancy around the time of diagnosis of breast cancer is expected to become increasingly common with maternal age at first childbirth on the rise, data on the prognostic impact of pregnancy have been inconsistent and rare from Asian populations. In this investigation of a Korean patient cohort with breast cancer, pregnancy-associated breast cancer was associated with advanced stage, younger age at diagnosis (

Background Immune cells in the tumour microenvironment play an essential role in tumorigenesis. This study aimed to evaluate the immunoregulatory protein expression of breast cancer and reveal their prognostic role. Methods Expression of 10 immune markers (PD-1/PD-L1/PD-L2/IDO/TIM-3/OX40/OX40L/B7-H2/ B7-H3/B7-H4) with known/possible clinical relevance was identified in stromal tumour-infiltrating lymphocytes or tumour tissue of stage I–III breast cancer patients. Results A total of 392 patients, including 271(69.1%) luminal A, 36(9.2%) luminal B, 32(8.2%) HER2-positive and 53(13.5%) triple negative disease, were included. Expression of PD-1 and PD-L1 was higher in HER2-positive and triple negative disease. By contrast, expression of TIM-3, OX40 and OX40L were higher in luminal disease. We devised an immune recurrence score (IRS) using seven markers with prognostic value (B7-H2/B7-H3/B7-H4/OX40/OX40L/PD-L1/PD-L2). Patients were classified as high-risk (7.9%), intermediate-risk (67.6%), or low-risk (24.5%). In the multivariate analysis, IRS low-risk (adjusted HR 0.14, p = 0.001) and intermediate-risk (adjusted HR 0.32, p = 0.002) had significantly lower risk of recurrence compared with high-risk. The prognostic role of IRS was maintained in both luminal A and non-luminal A patients. Conclusions This study identified immunoregulatory protein expression of breast cancer patients using 10 immune markers. In addition, we devised an IRS which may predict recurrence in stage I-III breast cancer patients.

Background FK506-binding protein 5 (FKBP5) binds to glucocorticoid receptors and modulates glucocorticoid sensitivity. The FKBP5 gene has been implicated in the dysregulation of human stress responses, contributing to the risk and treatment response of stress-related disorders. The present study examined whether epigenetic changes in FKBP5 are associated with chronic post-traumatic stress disorder (PTSD) status in the context of FKBP5 genetic variation (rs1360780 polymorphism) among male veterans exposed to combat trauma. Methods Korean male veterans who served on active duty during the Vietnam War were categorized into 2 groups: with PTSD (n = 123) and without PTSD (n = 116). The genotype of FKBP5 rs1360780 and DNA methylation levels of two CpG sites at the FKBP5 intron 7 region were assessed in peripheral blood. Analysis of covariance was performed to examine main and interaction effects of PTSD status and FKBP5 genotype on FKBP5 DNA methylation level, with age, trauma levels, and alcohol use as covariates. Results A significant main effect of FKBP5 rs1360780 and PTSD and an interaction effect between genotype and PTSD status were found on mean FKBP5 DNA methylation level. The T allele of rs1360780 was associated with lower FKBP5 methylation level. In addition, the PTSD group showed significantly higher methylation than did the non-PTSD group among veterans carrying the risk T allele (n = 96), while no group difference was observed on methylation levels among veterans with the CC genotype (n = 143). Among veterans carrying the T allele, FKBP5 methylation levels were positively correlated with the severity of PTSD symptoms. Conclusions The present study demonstrated different FKBP5 methylation levels in PTSD depending on FKBP5 genetic variation among veterans exposed to combat trauma. The present finding suggests that the genetic and epigenetic modulation of FKBP5 is involved in the pathophysiology of PTSD. Further longitudinal research involving people exposed to trauma is required to understand causal relationships of FKBP5 in the development and recovery of PTSD.

Although controversial, obesity and underweight may have a negative impact on breast cancer outcome. However, the relationship between body mass index (BMI) and breast cancer outcomes according to tumor subtype and menopausal status remains unclear. This study investigated the association between BMI and breast cancer outcome in stage I–III breast cancer patients. The relationships were further evaluated according to tumor subtype and menopausal status. A total of 5919 patients, 3475 (58.7%) hormone receptor (HR)(+) human epidermal growth factor receptor 2 (HER2)(–), 608 (10.3%) HR(+)HER2(+), 621 (10.5%) HR(–)HER2(+), and 1079 (18.2%) HR(–)HER2(–) were included. Underweight and obesity had a negative impact on relapse-free survival but did not affect overall survival. Importantly, the prognostic role of BMI was different according to tumor subtype and menopausal status. In HR(+)HER2(–) patients, underweight was associated with poor relapse-free survival and overall survival in pre-menopausal women. In contrast, obesity had negative impact on relapse-free survival and overall survival in HR(+)HER2(–) post-menopausal patients. Underweight may have a negative prognostic role in HR(+)HER2(+) patients. However, BMI did not impact the outcome of HR(–)HER2(+) and HR(–)HER2(–) patients. The impact of BMI on breast cancer outcome was dependent on tumor subtype and menopausal status. In HR(+)HER2(–) patients, underweight and obesity had a negative prognostic role in pre-menopausal and post-menopausal women, respectively. These findings in Asian population should be further evaluated and compared in Western population.

Purpose Pim kinases are highly conserved serine/threonine kinases, and different expression patterns of each isoform (Pim-1, Pim-2, and Pim-3) have been observed in various types of human cancers, including gastric cancer. AZD1208 is a potent and selective inhibitor that affects all three isoforms of Pim. We investigated the effects of AZD1208 as a single agent and in combination with an Akt inhibitor in gastric cancer cells. Materials and methods The antitumor activity of AZD1208 with/without an Akt inhibitor was evaluated in a large panel of gastric cancer cell lines through growth inhibition assays. The underlying mechanism was also examined by western blotting, immunofluorescence assay, and cell cycle analysis. Results AZD1208 treatment decreased gastric cancer cell proliferation rates and induced autophagy only in long-term culture systems. Light chain 3B (LC3B), a marker of autophagy, was increased in sensitive cells in a dose-dependent manner with AZD1208 treatment, which suggested that the growth inhibition effect of AZD1208 was achieved through autophagy, not apoptosis. Moreover, we found that cells damaged by Pim inhibition were repaired by activation of the DNA damage repair pathway, which promoted cell survival and led the cells to become resistant to AZD1208. We also confirmed that the combination of an Akt inhibitor with AZD1208 produced a highly synergistic effect in gastric cancer cell lines. Conclusion Treatment with AZD1208 alone induced considerable cell death through autophagy in gastric cancer cells. Moreover, the combination of AZD1208 with an Akt inhibitor showed synergistic antitumor effects through regulation of the DNA damage repair pathway.

Background Poziotinib (HM781-36B) is an irreversible pan-HER tyrosine kinase inhibitor which targets EGFR, HER2, and HER4. This prospective, multicenter, open-label, phase I/II study determined the maximum tolerated dose (MTD) and evaluated the safety and efficacy of poziotinib combined with paclitaxel and trastuzumab in patients with HER2-positive advanced gastric cancer (GC). Methods Patients with HER2-positive GC previously treated with one line of chemotherapy received oral poziotinib (8 mg or 12 mg) once daily for 14 days, followed by 7 days off. Paclitaxel (175 mg/m2 infusion) and trastuzumab (8 mg/kg loading dose, then 6 mg/kg infusion) were administered concomitantly with poziotinib on day 1 every 3 weeks. Results In the phase I part, 12 patients were enrolled (7 at dose level 1, 5 at dose level 2). One patient receiving poziotinib 8 mg and 2 receiving poziotinib 12 mg had dose-limiting toxicities (DLTs); all DLTs were grade 4 neutropenia, one with fever. The most common poziotinib-related adverse events were diarrhea, rash, stomatitis, pruritus and loss of appetite. The MTD of poziotinib was determined to be 8 mg/day and this was used in the phase II part which enrolled 32 patients. Two patients (6.3%) had complete responses and 5 (15.6%) had partial responses (objective response rate 21.9%). Median progression-free survival and overall survival were 13.0 weeks (95% CI 9.8-21.9) and 29.5 weeks (95% CI 17.9-59.2), respectively. Conclusions The MTD of poziotinib combined with paclitaxel and trastuzumab was 8 mg/day. This combination yielded promising anti-tumor efficacy with manageable toxicity in previously treated patients with HER2-positive GC.

Persistence of thyroglobulin antibody (TgAb) in patients with papillary thyroid carcinoma (PTC) years after total thyroidectomy (TT) followed by ablation occurs even without any evidence of structural disease. Few studies have studied the natural course of TgAb positivity and factors that may influence this course. The present study evaluated the time trends of TgAb in ablated PTC patients and aimed to identify the predictive factors for the rate of negative conversion of TgAb.Overall, 1279 patients who underwent TT and subsequent ablation for PTC, with available data on thyroid peroxidase Ab (TPOAb) and TgAb prior to surgery (preop-) and ablation (abl-) were enrolled. Patients with initial distant metastasis or recurrence during follow-up were excluded.Preop-TgAb was positive in 24.9% of patients (n = 319), whereas abl-TgAb positivity decreased to 12.8% (n = 164). In 164 patients positive for abl-TgAb, TgAb in patients with higher abl-TgAb levels decreased more gradually than those observed in patients with lower abl-TgAb levels (p 0.001). Furthermore, in patients within the same range of abl-TgAb levels, patients positive for abl-TPOAb had a higher rate of negative conversion of TgAb compared with negative patients for abl-TPOAb (log rank p 0.001). TPOAb significantly increased the rate of negative conversion in multivariate analysis adjusted for abl-TgAb (odds ratio 1.59, 95% confidence interval 1.11-2.28, p = 0.011). This study clearly showed that abl-TgAb titers and abl-TPOAb status can predict the rate of negative conversion. These findings can guide the optimal timing for additional examination in patients positive for TgAb during follow-up.

Patients with differentiated thyroid carcinoma (DTC) are staged according to the single age cut point in addition to anatomic extent. A novel staging system is needed to properly show the character and prognosis of DTC by considering age as a continuous variable. We aimed to refine stage and prognostic groups of the eighth edition tumor-node-metastasis (TNM-8) staging system for DTC and to suggest a possible revision.We conducted a retrospective data abstraction study of patients with newly diagnosed DTC who were treated at one of two tertiary referral centres in Seoul, Korea between 1994 and 2005. We used recursive partitioning analysis to derive a new staging classification (TNM-RPA) and compared its prediction of cancer-specific survival with that of TNM-8.The cohort comprised 6342 patients with DTC who were followed up for a median of 11.4 years. Higher TNM-RPA groups were associated with increased risk of death (10-year cancer-specific survival for stages IA, IB, IIA, IIB, III, and IV: 99.6%, 98.1%, 93.0%, 92.4%, 75.1%, and 56.6%, respectively; P 0.001). The C-index values were 0.869 (95% CI, 0.833-0.905) for the TNM-RPA and 0.819 (0.789-0.850) for TNM-8. The proportions of variance explained for the ability of the TNM-RPA and TNM-8 stages to predict cancer-specific survival were 7.1% and 5.7%, respectively.This study presents a RPA-based TNM stage groupings that incorporate multiple age cutoffs and essential anatomic information, which can be conveniently used to facilitate the individual prediction of long-term cancer-specific survival in patients with DTC.

Purpose: Immune checkpoint inhibitors (ICIs) have revolutionized the cancer prognosis in various cancer types. However, ICIs may trigger accelerated tumor progression, regarded as hyperprogressive disease (HPD), in certain patients, and it is still challenging to define HPD. We aimed to investigate the landscape of HPD and the prognostic value of its different definitions in advanced solid cancer patients treated with ICIs. Methods: We conducted a multicenter, prospective cohort study for solid cancer patients receiving ICIs. Among them, only unresectable or metastatic cancer patients were included in this analysis. Tumor response was evaluated according to RECIST 1.1. In patients who showed progressive disease (PD) by RECIST 1.1 at the first tumor evaluation, HPD was defined according to the following three criteria: A) tumor growth kinetics (TGK) ratio (TGKpost-ICI/TGKpre-ICI >=2, B) >=10mm increase in sum of target lesion (SUMtarget)and at least one of the following two criteria - 1) >=40% increase in SUMtarget or 2) >=20% increase in SUMtarget and the appearance of new lesions in at least two different organs, C) TGK ratio >=2 and >50% increase in SUMtarget. The discriminatory ability of three definitions in terms of overall survival (OS) were evaluated by the chi-square, C-statistics, and prediction error with integrated Brier score. Results: A total of 427 patients were included; head and neck (n=22, 5.2%), lung (n=173, 40.5%), breast (n=8, 1.9%), gastrointestinal tract (n=99, 23.2%), hepatobiliary pancreas (n=57, 13.3%), genitourinary (n=56, 13.1%), melanoma (n=5, 1.2%), and others (n=7, 1.6%). Incidences of HPD were 4.9%, 14.8%, and 11.5% in definition A, B, C, respectively. The incidence of HPD was relatively low (2.7%-9.5%) in non-small cell lung cancer compared to other cancer types (10.1%-21.5% in esophagogastric cancer, 3.9%-21.6% in hepatobiliary pancreas cancer, and 5.5%-22.5% in genitourinary cancer). Median OS was the worst for patients with HPD, which ranged from 4.8 months to 4.9 months according to definition A-C. After multivariate analysis adjusting for cancer types, ICIs types, and the number of prior anti-cancer therapy, each definition remained a significant factor for OS (P Conclusions: Incidences of HPD appear to be various according to its definitions and cancer types. Given that the RECIST-based definition B not requiring pre-ICI imaging, showed similar discriminatory ability to predict dismal OS compared to TGK-based ones, it may be the most feasible and convenient measure to capture HPD in daily clinical practice. Citation Format: Jwa Hoon Kim, Soohyeon Lee, Min Hee Hong, Jee Hyun Kim, Eun Joo Kang, Tae-Yong Kim, Yeon Hee Park, Ji-Youn Han, Il-Hwan Kim, Sang-We Kim, Dae Ho Lee, Jae Lyun Lee, Jae Cheol Lee, Chang-Min Choi, Changhoon Yoo, Shinkyo Yoon, Jae Ho Jeong, Seyoung Seo, Sun Young Kim, Jin-Hee Ahn, Sook Ryun Park. Hyperprogression in various solid cancers treated with immune checkpoint inhibitors in the real world [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 5209.

Background: Human epithelial growth factor receptor 2 (HER2) is a well-established therapeutic target in HER2-positive breast and gastric cancer. Recently, novel HER2-targeting agents are being developed after trastuzumab, and HER2-targeted therapies have been attempted in across solid tumor types, including biliary tract cancer. In these aspects, it is essential to understand and elucidate the resistant mechanism of the HER2-targeting strategies. Yes-associated protein (YAP), a transcription factor of the Hippo pathway, function as proto-oncoproteins by inducing target genes involved in cancer cell survival and proliferation (Zhao B, et al. Genes Develop 2008). Also, YAP is emerging as a resistance mechanism of cytotoxic and targeted drugs. In this study, we explore the role of YAP in overcoming resistance to trastuzumab in HER2-positive cancer cells. Methods: Four trastuzumab-resistant (HR) cell lines were established using HER2-postive gastric and biliary tract cancer cell lines (N87, SNU216, SNU2670, and SNU2773) (Jin MH, et al. Mol Cancer Ther. 2017). YAP siRNA and Verteporfin (YAP-TEAD inhibitor) were used to downregulate YAP. MTT assay, cell cycle analysis, western blot and migration assay were performed to analyze the antitumor effects through YAP downregulation. In order to elucidate tumor cell immune-modulation by YAP, human PBMC co-culture was used and immune markers, such as programmed death-ligand 1 (PD-L1), were analyzed in HR cell lines. Results: Increase of receptor tyrosine kinase-like orphan receptor 1/2 (ROR1/2) expression was observed in the HR cells. Relatively high expression of pYAP, YAP, and transcriptional co-activator with PDZ-binding motif (TAZ) were observed in the HR cells (SNU216HR, SNU2670HR and SNU2773HR) compared to parental cells. Reducing overexpressed YAP in HR cells resulted in tumor cell growth inhibition. In cell cycle analysis, the increase of subG1 phase through YAP downregulation was observed, and cyclinD, B, A and BCL-XL were effectively decreased. Migration was also inhibited by the decrease in YAP expression. By verteporfin treatment, changes in immune markers including increase of CD80 and decrease of PD-L1 was found. In addition, p-STAT3 and IL6, Which regulate PD-L1, were also decreased through the reduction of YAP. In HR cells treated with siYAP, there was a tendency to increase CD8+ T cells upon PBMC co-culture. Conclusion: YAP is upregulated in trastuzumab-resistant (HR) cells and upregulated YAP induce PD-L1 expression. Inhibition of YAP shows anti-tumor effects and modulates immune status. Collectively, our results suggest that inhibition of YAP is one of promising strategies to overcome trastuzumab resistance in HER2-positive cancers. Citation Format: Ah Rong Nam, Jeesun Yoon, Kyoung-Seok Oh, Jae-Min Kim, Ju-Hee Bang, Tae-Yong Kim, Do-Youn Oh. Targeting the hippo transducer YAP overcomes trastuzumab-resistance in HER2-positive cancers [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 5334.

4117 Background: In the phase 2 (NCT03046862), gemcitabine/cisplatin (GemCis) and durvalumab (D) ± tremelimumab (T) in chemotherapy-naïve advanced biliary tract cancer (BTC) showed a high objective response rate and durable clinical benefit. Based on this study, phase 3 trial (TOPAZ-1, NCT03875235) has been conducted and the positive result for adding D to GemCis has been reported. Health-related quality of life (HRQoL) for adding immunotherapy to cytotoxic chemotherapy in BTC has not been reported yet. We present HRQoL results from the phase 2 study. Methods: In this study, treatment-naïve patients with unresectable or recurrent BTC were enrolled into three cohorts. Patients received one cycle of GemCis followed by GemCis plus D and T (cohort 1) or, starting with the first cycle, received GemCis plus D (cohort 2) or GemCis plus D and T (cohort 3). The EORTC Quality of Life Questionnaire (QLQ)-C30 and BIL21 were administered at baseline and every cycle throughout treatment. Change from baseline to post-2 cycles and deterioration of HRQoL (≥10 points change) were analysed. Results: At data cut-off (March 22, 2021), 126 patients (32 in cohort 1, 47 in cohort 2, 47 in cohort 3) were included for this analysis. Compliance for QLQ was very high ( > 90 %) at all time points. C30 global health status (GHS) scores remained stable at all time points and from baseline to post 2 cycles (mean [95% CI] change, 2.66 [-1.10‒6.42]), with greater improvements observed in patients with responder (a best response of complete response (CR) or partial response (PR)) (3.60 [-1.27 to 8.47]) compared to non-responder (stable disease (SD) or progressive disease (PD) (0.66 [-5.19 to 6.51]). For the overall cohort, functioning scales also remained stable from baseline to post 2 cycles. Nausea/vomiting (8.4 [4.45 to 12.36]), dyspnea (7.28 [2.17 to 12.4]), constipation (9.24 [3.35 to 15.13]), financial difficulties (5.53 [1.65 to 9.41]) in C30 and eating (5.53 [1.65 to 9.41]), tiredness (5.42 [1.23 to 9.6]), treatment side effects (7.98 [1.15 to 14.81] in BIL21 were worse at post 2 cycles. However, pain (-7.14 [-12.24 to -2.04]), diarrhea (-4.48 [-8.86 to -0.1]) in C30 and jaundice (-5.51 [-9.26 to -1.76]), pain (-6.02 [-9.7 to -2.34] in BIL21 were improved and more improvement was shown in responder compared to non-responder. Regarding deterioration of C30 GHS, median deterioration-free survival (months [95% CI]) was 4.14 (2.66-6.47) in all cohorts and there was no difference between responder (3.68 [2.27-7.92]) and non-responder (5.59 [2.73-9.46], Hazard ratio = 1.00 [95% CI, 0.62-1.61], p = 0.997). There was no difference among 3 cohorts. Conclusions: GemCis plus D ± T in chemotherapy-naïve advanced BTC generally preserved HRQoL and improved some symptom scales such as jaundice and pain although chemotherapy related symptom scales were worse.

2501 Background: The immunoregulatory cytokine IL-27 upregulates inhibitory immune checkpoint receptors (eg, PD-L1, TIGIT) and downregulates proinflammatory cytokines (eg, IFNγ, TNFα). SRF388 is a fully human IgG1 blocking antibody to IL-27 with potential to promote immune activation in the tumor microenvironment. A phase 1 study was conducted to establish the preliminary safety of SRF388 and to identify recommended phase 2 doses (RP2D) suitable for monotherapy and combination expansions (NCT04374877). Methods: The dose-escalation study (accelerated single patient followed by standard 3+3) enrolled patients (pts) with advanced treatment-refractory solid tumors. Upon RP2D selection, monotherapy and combination expansions opened for treatment-refractory clear cell renal cell cancer (ccRCC), hepatocellular cancer (HCC), and non-small cell lung cancer. SRF388 was administered IV every 4 weeks (wks) as monotherapy and every 3 wks with pembrolizumab. Tumor response was assessed by RECIST1.1. Results: The monotherapy dose-escalation enrolled 29 pts with doses ranging from 0.003 to 20 mg/kg. Median age was 64 years. Most pts were female (62%) with ECOG PS of 1 (72%). Approximately 80% had prior PD-(L)1 blockade, and 48% had ≥4 prior therapies. Treatment-related adverse events (TRAEs) occurred in 21%, and all were low grade. Fatigue was the only TRAE reported in ≥10% (n = 3). No dose-limiting toxicities (DLTs) or Grade ≥3 TRAEs were observed. Median time on study was 9 wks (range 0–59). One patient with highly treatment-refractory NSCLC experienced a confirmed partial response (PR) at 8 wks that was durable for 20 wks. Nine pts (31%) experienced disease stabilization at 8 wks, with 6 of 9 exhibiting durable disease control at 6 months. Of the 7 pts with ccRCC in the dose-escalation portion of the trial, 3 (43%) experienced durable disease control for ≥20 wks (range: 20-32). With doses up to 20 mg/kg, SRF388 PK remain linear with an estimated T1/2 of 10-12 days. PK characteristics and safety profile support dosing every 3 or 4 wks. Based on safety, tolerability, PK, peripheral pSTAT1 inhibition, and preliminary efficacy, 10 mg/kg was selected as the RP2D. Both the pembrolizumab safety cohort (n = 10) and Stage 1 of the ccRCC monotherapy expansion (n = 17) have fully enrolled. Of the 10 evaluable pts with ccRCC, 1 confirmed monotherapy PR has been reported, enabling Stage 2 initiation. Changes in several serum cytokines and chemokines were observed after SRF388 administration, including expected increase in circulating IL-27 levels. Conclusions: Results of IL-27 pathway blockade with a first-in-class therapeutic demonstrates that SRF388 has good tolerability with encouraging preliminary antitumor activity as a monotherapy. Updated data, including safety and clinical outcomes as well as correlative biomarker analyses, will be presented. Clinical trial information: NCT04374877.