The Impact of Pembrolizumab as a Salvage Therapy Based on HER2 Expression in Advanced Gastric Cancer.

Immune checkpoint inhibitors (ICIs) are used as salvage treatments for advanced gastric cancer (AGC) regardless of HER2 status. This study assessed the efficacy of ICIs based on HER2 expression in AGC patients who received pembrolizumab as salvage monotherapy at Samsung Medical Center from November 2017 to March 2023. HER2 status was determined via immunohistochemistry, and tumor response and survival outcomes were compared accordingly. Among the 113 patients analyzed, with a median age of 61 years and 64.6% being male, 12 patients (10.6%) were HER2-positive, and 101 patients (89.4%) were HER2-negative. Of 92 evaluable patients, none had a complete response. However, 50% of HER2-positive patients had a partial response, compared to 4.9% of HER2-negative patients (p < 0.001). The disease control rate was 70% in HER2-positive and 37.8% in HER2-negative patients (p = 0.086). Median progression-free survival was 5.53 months for HER2-positive patients versus 1.81 months for HER2-negative patients (p = 0.037). Pembrolizumab as a salvage chemotherapy for the treatment of AGC demonstrated superior effectiveness in HER2-positive patients compared with HER2-negative patients.

Prevalence of KRAS amplification in patients with metastatic cancer: Real-world next-generation sequencing analysis.

BACKGROUND: The Kirsten rat sarcoma virus (KRAS) is a prominent proto-oncogene. Several treatments for KRAS mutations have been developed. However, KRAS amplification, a KRAS alteration, is poorly understood, and there is currently no appropriate treatment other than conventional chemotherapy. This study aimed to elucidate the role of KRAS amplification in different types of cancers. METHODS: From October 2019 to June 2023, we performed next-generation sequencing using Trusight Oncology 500 on 3895 patients with 37 different cancer types at the Samsung Medical Center. We analyzed the distribution of KRAS amplification according to cancer type and its correlation with tumor mutation burden (TMB). Concomitant KRAS mutations were also identified. RESULTS: Of the total 3895 patients, 99 (2.5 %) had KRAS amplification. The highest frequency of KRAS amplification was detected in 2 % (27/1350) of patients with colorectal cancer, followed by 3.48 % (32/920) of patients with gastric cancer and 3.88 % (9/232) patients with of pancreatic cancer. MSI-High was not detected in patients with KRAS amplification. There was no correlation between KRAS copy number variation and TMB status. Among patients with KRAS amplification, 27.3 % (27/99) had a concomitant KRAS mutation. More than 50 % of patients had G12D or G12V mutations. In gastric cancer, patients with both KRAS amplification and mutation were extremely rare at 3.1 % (1/32); however, in colorectal cancer, more than half of the patients had KRAS amplification and mutation (51.9 %, 14/27). KRAS amplification and mutations are associated with mutations in tumor suppressor genes TP53, BRCA2, ARID1B, and PTCH1. CONCLUSIONS: Of the 3895 patients with metastatic solid tumors, 99 (2.5 %) had KRAS amplification, and next-generation sequencing analysis provided a deeper understanding of KRAS amplification.

Efficacy of chemotherapy containing bevacizumab in patients with metastatic colorectal cancer according to programmed cell death ligand 1.

BACKGROUND: Bevacizumab, an anti-vascular endothelial growth factor (VEGF) monoclonal antibody, inhibits angiogenesis and reduces tumor growth. Serum VEGF-C, lactate dehydrogenase, and inflammatory markers have been reported as predictive markers related to bevacizumab treatment. Programmed cell death ligand 1 (PD-L1) could act upon VEGF receptor 2 to induce cancer cell angiogenesis and metastasis. AIM: To investigate the efficacy of bevacizumab-containing chemotherapy in patients with metastatic colorectal cancer (CRC) according to the expression of PD-L1. METHODS: This analysis included CRC patients who received bevacizumab plus FOLFOX or FOLFIRI as first-line therapy between June 24, 2014 and February 28, 2022, at Samsung Medical Center (Seoul, South Korea). Analysis of patient data included evaluation of PD-L1 expression by the combined positive score (CPS). We analyzed the efficacy of bevacizumab according to PD-L1 expression status in patients with CRC. RESULTS: A total of 124 patients was included in this analysis. Almost all patients were treated with bevacizumab plus FOLFIRI or FOLFOX as the first-line chemotherapy. While 77% of patients received FOLFOX, 23% received FOLFIRI as backbone first-line chemotherapy. The numbers of patients with a PD-L1 CPS of 1 or more, 5 or more, or 10 or more were 105 (85%), 64 (52%), and 32 (26%), respectively. The results showed no significant difference in progression-free survival (PFS) and overall survival (OS) with bevacizumab treatment between patients with PD-L1 CPS less than 1 and those with PD-L1 CPS of 1 or more (PD-L1 < 1% vs PD-L1 ≥ 1%; PFS: P = 0.93, OS: P = 0.33), between patients with PD-L1 CPS less than 5 and of 5 or more (PD-L1 < 5% vs PD-L1 ≥ 5%; PFS: P = 0.409, OS: P = 0.746), and between patients with PD-L1 CPS less than 10 and of 10 or more (PD-L1 < 10% vs PD-L1 ≥ 10%; PFS: P = 0.529, OS: P = 0.568). CONCLUSION: Chemotherapy containing bevacizumab can be considered as first-line therapy in metastatic CRC irrespective of PD-L1 expression.

CDK4/6 inhibition to resensitize BRAF/EGFR inhibitor in patient-derived BRAF/PTEN-mutant colon cancer cells.

Background: In v-raf murine sarcoma viral oncogene homolog B1 (BRAF)-mutant colorectal cancer (CRC), encorafenib-cetuximab has been established as standard second-line therapy, but not all patients respond and the duration of response is relatively short. Overcoming intrinsic or acquired resistance to BRAF/EGFR inhibitors is crucial for enhancing treatment outcomes in metastatic BRAF-mutated CRC. The aim of the study is to investigate the resistance mechanisms in BRAF-mutant CRC patient refractory to BRAF/EGFR targeted therapy. Methods: We established patient-derived cells (PDCs) from a patient with BRAF/PTEN-mutant metastatic colon cancer who progressed rapidly on encorafenib plus cetuximab. To explore potential treatment options for inherent resistance caused by simultaneous PTEN mutation in BRAF-mutated CRC, we conducted cell viability assays using PDCs treated with encorafenib-cetuximab in combination with a cyclin-dependent kinase-4 and 6 (CDK4/6) inhibitor. Results: The patient's tumor had concurrent PTEN loss-of-function alteration at diagnosis and PDCs were generated from ascites after resistance to the BRAF/EGFR inhibitor. The PDCs were resistant to the encorafenib-cetuximab combination even at a high concentration of cetuximab (up to 500 µg/mL). Adding the CDK4/6 inhibitor, ribociclib, to encorafenib-cetuximab showed a synergistic effect in a proliferation assay. Ribociclib plus encorafenib-cetuximab represented a significantly lower expression of Ki-67 compared to the dual combination alone. An MTS assay showed that triplet therapy with ribociclib, encorafenib, and cetuximab suppressed cell viability more efficiently than the two-drug combinations. Investigating the combined effect of triplet therapy using the calculated combination index (CI) showed that ribociclib had a synergistic effect with encorafenib-cetuximab when applied to PDCs with a concurrent BRAF/PTEN mutation. Conclusions: Our results suggest that combining the CDK4/6 inhibitor with the BRAF/EGFR inhibitor might be a novel treatment strategy for concomitant BRAF and PTEN-mutant CRC.

The safety and efficacy outcomes of Minnelide given alone or in combination with paclitaxel in advanced gastric cancer: A phase I trial.

Minnelide is a water-soluble disodium salt variant of triptolide, an HSP70 inhibitor that can prevent tumor progression and induce apoptosis. Maximum tolerated dose (MTD), safety, and antitumor activity of Minnelide alone and its combination with paclitaxel were evaluated in this open-label, single-center, dose-escalation phase I study (NCT05566834) in patients who were previously treated for advanced gastric cancer (AGC). Minnelide was administered orally using a 3 + 3 dose-escalation design as monotherapy (Regimen A), and in combination with paclitaxel (Regimen B & C). Our results show that no patients experienced dose limiting toxicity (DLT) in the combination group (Regimen B& C) while 2 patients experienced DLT from the Regimen A group (n = 11) (Minnelide 1.5 mg). The MTD was Minnelide 1.25 mg once daily for 21days Q4 weeks as monotherapy. The most common Grade ≥3 AEs were neutropenia (19.4 %) and abdominal pain (11.1 %). In Regimen C, 71.5 % achieved either a partial response or a stable disease with the median PFS of 4.5 months, and the median OS of 10.7 months. The combination of Minnelide plus paclitaxel as salvage treatment in AGC patients showed meaningful clinical activity with a manageable safety profile. Based on these encouraging results, a phase II study is being initiated to test the effectiveness of the combination regimen in patients with advanced gastric cancer.

Neoadjuvant Cisplatin-Based Chemotherapy Followed by Selective Bladder Preservation Chemoradiotherapy in Muscle-Invasive Urothelial Carcinoma of the Bladder: Post Hoc Analysis of Two Prospective Studies.

PURPOSE: Bladder preservation chemoradiotherapy (CRT) in patients with a clinical complete response (cCR) following cisplatin-based neoadjuvant chemotherapy (NAC) is a promising treatment strategy for muscle-invasive bladder urothelial carcinoma (MIBC). A combined analysis of raw data from two prospective phase II studies was performed to better evaluate the feasibility of selective bladder preservation CRT. MATERIALS AND METHODS: The analysis was based on primary efficacy data from two independent studies, including 76 MIBC patients receiving NAC followed by bladder preservation CRT. The efficacy data included metastasis-free survival (MFS) and disease-free survival (DFS). For the present analysis, starting point of survival was defined as the date of commencing CRT. RESULTS: Among 76 patients, 66 had a cCR following NAC. Sixty-four patients received gemcitabine and cisplatin (GC) combination chemotherapy in neoadjuvant setting, and 12 received nivolumab plus GC. Bladder preservation CRT following NAC was generally well-tolerated, with low urinary tract symptoms being the most common late complication. With a median follow-up of 64 months, recurrence was recorded in 43 patients (57%): intravesical only (n=20), metastatic only (n=16), and both (n=7). In 27 patients with intravesical recurrence, transurethral resection, and Bacillus Calmette-Guerin treatment was given to 17 patients. Salvage cystectomy was performed in 10 patients. Median DFS was 46.3 (95% confidence interval [CI], 25.1 to 67.5) months, and the median MFS was not reached. Neither DFS nor MFS appeared to be affected by any of the baseline characteristics. However, DFS was significantly longer in patients with a cCR than in those without (hazard ratio, 0.465; 95% CI, 0.222 to 0.976). CONCLUSION: The strategy of NAC followed by selective bladder preservation CRT based on the cCR is feasible in the treatment of MIBC. A standardized definition of cCR is needed to better assess disease status post-NAC.

Real-world outcomes of third-line immune checkpoint inhibitors versus irinotecan-based chemotherapy in patients with advanced gastric cancer: a Korean, multicenter study (KCSG ST22-06).

BACKGROUND: Immune checkpoint inhibitor (ICI) or irinotecan-based chemotherapy is frequently used after failure of second-line paclitaxel plus ramucirumab treatment for patients with locally advanced unresectable or metastatic advanced gastric cancer (AGC). This study aimed to compare the efficacy between ICI and irinotecan-based chemotherapy as third-line treatment in patients with AGC. METHODS: We retrospectively reviewed patients with AGC, whose third-line treatment started between July 2019 and June 2021 at 17 institutions in Korea. The ICI group included patients who received nivolumab or pembrolizumab, and the irinotecan-based chemotherapy group included patients who received irinotecan or FOLFIRI (5-fluorouracil, leucovorin and irinotecan). RESULTS: A total of 363 patients [n = 129 (ICI) and n = 234 (irinotecan-based chemotherapy)] were analyzed. The median progression-free survival was 2.3 and 2.9 months in ICI and irinotecan-based chemotherapy groups, respectively (p = 0.802). The median overall survival (OS) was 5.5 and 6.0 months in ICI and irinotecan-based chemotherapy groups, respectively (p = 0.786). For all patients included in this study, multivariable analysis showed that weight loss, peritoneal metastasis, low serum sodium or albumin, and short duration of second-line treatment were associated with inferior OS (p < 0.05). ICI showed significantly longer OS than irinotecan-based chemotherapy in patients without peritoneal metastasis. Whereas ICI showed significantly shorter OS in patients without PD-L1 expression than irinotecan-based chemotherapy. CONCLUSIONS: No significant difference in survival outcome was observed between ICI and irinotecan-based chemotherapy as third-line treatment for AGC patients. ICI might be preferred for patients without peritoneal metastasis and irinotecan-based chemotherapy for patients with tumors without PD-L1 expression. TRIAL REGISTRATION: This study was registered in the Clinical Trial Registry of Korea ( https://cris.nih.go.kr : KCT 0007732).

Patient-derived tumor spheroid-induced angiogenesis preclinical platform for exploring therapeutic vulnerabilities in cancer.

This study addresses the demand for research models that can support patient-treatment decisions and clarify the complexities of a tumor microenvironment by developing an advanced non-animal preclinical cancer model. Based on patient-derived tumor spheroids (PDTS), the proposed model reconstructs the tumor microenvironment with emphasis on tumor spheroid-driven angiogenesis. The resulting microfluidic chip system mirrors angiogenic responses elicited by PDTS, recapitulating patient-specific tumor conditions and providing robust, easily quantifiable outcomes. Vascularized PDTS exhibited marked angiogenesis and tumor proliferation on the microfluidic chip. Furthermore, a drug that targets the vascular endothelial growth factor receptor 2 (VEGFR2, ramucirumab) was deployed, which effectively inhibited angiogenesis and impeded tumor invasion. This innovative preclinical model was used for investigating distinct responses for various drug combinations, encompassing HER2 inhibitors and angiogenesis inhibitors, within the context of PDTS. This integrated platform could potentially advance precision medicine by harmonizing diverse data points within the tumor microenvironment with a focus on the interplay between cancer and the vascular system.

Adjuvant Chemotherapy for Upper Tract Urothelial Carcinoma: A Real-World, Retrospective Study.

PURPOSE: The aim of this retrospective study was to evaluate the efficacy of adjuvant cisplatin-based chemotherapy in patients with locally advanced upper tract urothelial carcinoma (UTUC), administered following radical nephroureterectomy. MATERIALS AND METHODS: Patients with UTUC, arising from renal pelvis or ureter, staged pT3/T4 or N+ were treated with adjuvant chemotherapy following surgery. The chemotherapy consisted of gemcitabine 1,000 mg/m2 on days 1 and 8, cisplatin 70 mg/m2 on day 1. Treatment was repeated every 3 weeks for up to 4 cycles. Endpoints included disease-free survival (DFS), metastasis-free survival (MFS), and safety. RESULTS: Among 89 eligible patients, 85 (95.5%) completed at least 3 cycles of adjuvant chemotherapy. Chemotherapy was well tolerated, the main toxicities being mild-to-moderate gastrointestinal toxic effects and pruritus. With a median follow-up of 37 months, median DFS was 30 months (95% confidence interval, 22 to 39), and the median MFS was not reached. The 3-year DFS and MFS were 44% and 56%, respectively. Multivariate analyses revealed that the main factor associated with DFS and MFS was the lymph node involvement, whereas age, T category, grade, or the primary site of UTUC were not significantly associated with DFS or MFS. CONCLUSION: Adjuvant cisplatin-based chemotherapy after radical surgery of pT3/T4 or N+ UTUC was feasible and may demonstrate benefits in DFS and MFS. Whether novel agents added to the chemotherapy regimen, as a concurrent combination or maintenance, impacts on survival or reduces the development of metastases remains to be studied.

Treatment Patterns and Prognosis of Palliative Chemotherapy Combined With Targeting Agents in Patients With Unresectable Metastatic Colorectal Cancer: CHOICE, A Multicenter Longitudinal Observational Study.

BACKGROUND/AIM: This study investigated the treatment patterns and prognosis of patients with metastatic or unresectable colorectal cancer (mCRC) treated with chemotherapy with targeting agents. PATIENTS AND METHODS: This longitudinal multicenter study included 963 patients with mCRC who were treated in Korea between 2016 and 2020. Treatment patterns and efficacy were compared according to the mutation status and clinical factors. RESULTS: As first-line therapy, most of the patients (83.5%) received FOLFOX plus bevacizumab (35.4%), followed by FOLFIRI plus bevacizumab (18.8%), FOLFIRI plus cetuximab (17.0%), and FOLFOX plus cetuximab (12.3%). Bevacizumab was the most frequent agent (78.8%) combined with chemotherapy in RAS-mutated CRC, while cetuximab (57.2%) in RAS wild-type CRC. Cetuximab was frequently combined with a doublet regimen in patients with left-sided CRC than in those with right-sided CRC (34.4% vs. 16%). As second-line therapy, most patients (63.4%) also received doublet regimens with bevacizumab, and FOLFIRI plus aflibercept was administered in 15.1%. The objective response rate with FOLFIRI plus cetuximab was significantly higher in patients with left-sided CRC than in those with right-sided CRC (59.2% vs. 30.8%, p=0.008) and marginally higher in patients with RAS wild-type CRC than in those with RAS-mutated CRC (55.6% vs. 0.0%, p=0.092). Progression-free survival (PFS) with FOLFOX plus bevacizumab was significantly shorter than that with FOLFIRI plus bevacizumab (p=0.030) in RAS-mutated CRC, whereas there were no significant differences between regimens in RAS wild-type CRC. CONCLUSION: In patients with unresectable metastatic colorectal cancer, doublet chemotherapy with targeting agents is the most common therapy and efficacy depends on the mutation status as well as clinical factors.

Prevalence of RAF1 Aberrations in Metastatic Cancer Patients: Real-World Data.

PURPOSE: Therapeutic targeting of RAF1 is a promising cancer treatment, but the relationship between clinical features and RAF1 aberrations in terms of the MAPK signaling pathway is poorly understood in various solid tumors. METHODS: Between October 2019 and June 2023 at Samsung Medical Center, 3895 patients with metastatic solid cancers underwent next-generation sequencing (NGS) using TruSight Oncology 500 (TSO500) assays as routine clinical practice. We surveyed the incidence of RAF1 aberrations including mutations (single-nucleotide variants [SNVs]), amplifications (copy number variation), and fusions. RESULTS: Among the 3895 metastatic cancer patients, 77 (2.0%) exhibited RAF1 aberrations. Of these 77 patients, 44 (1.1%) had RAF1 mutations (SNV), 25 (0.6%) had RAF1 amplifications, and 10 (0.3%) had RAF1 fusions. Among the 10 patients with RAF1 fusions, concurrent RAF1 amplifications and RAF1 mutations were detected in one patient each. The most common tumor types were bladder cancer (11.5%), followed by ampulla of Vater (AoV) cancer (5.3%), melanoma (3.0%), gallbladder (GB) cancer (2.6%), and gastric (2.3%) cancer. Microsatellite instability high (MSI-H) tumors were observed in five of 76 patients (6.6%) with RAF1 aberrations, while MSI-H tumors were found in only 2.1% of patients with wild-type RAF1 cancers (p < 0.0001). CONCLUSION: We demonstrated that approximately 2.0% of patients with metastatic solid cancers have RAF1 aberrations according to NGS of tumor specimens.

Effect of human epidermal growth factor receptor 2 overexpression in metastatic colorectal cancer on standard chemotherapy outcomes.

Background: In metastatic colorectal cancer (mCRC), the prognostic relevance of the human epidermal growth factor receptor-2 (HER2) remains controversial. We evaluated the impact of HER2 overexpression on outcomes of standard chemotherapy in patients with mCRC. Methods: This retrospective study included patients with mCRC who received standard chemotherapy for mCRC and were tested for HER2 expression at Samsung Medical Center, Seoul, Korea, between January 15, 2017, and February 05, 2022. The HER2 test was performed using immunohistochemistry. We assessed the objective response rate (ORR), overall survival (OS), and progression-free survival (PFS) according to HER2 status. All statistical analyses were performed using SPSS® version 25 (IBM, Armonk, NY, USA). Results: In total, 108 patients were included; 10 (9.3%) had HER2-positive tumors. The ORR for patients with mCRC receiving standard chemotherapy did not differ for HER2-positive and HER2-negative tumors. The median PFS for patients with mCRC with HER2-positive or HER2-tumors after receiving first-line chemotherapy was 18.52 months [95% confidence interval (CI): 4.355-32.695] or 10.95 months (95% CI: 9.317-12.585; P=0.417), respectively, and that after second-line chemotherapy was 7.08 months (95% CI: 6.801-7.363) or 5.34 months (95% CI: 4.433-6.255; P=0.837), respectively. Likewise, OS did not differ according to HER2 expression (median OS: HER2-positive tumors, 49.1 months (95% CI: 0.000-98.365); HER2-negative tumors, 37.7 months (95% CI: 27.111-48.366; P=0.410). Conclusions: The tumor response and survival of patients with mCRC after standard chemotherapy did not differ by HER2 expression. These findings suggest that the status of HER2 expression need not be considered when choosing regimens as the current first- and second-line treatments.

Is Treosulfan-Based Conditioning Attractive as a Reduced-Intensity Conditioning Regimen in Korea?

BACKGROUND: Allogeneic hematopoietic stem cell transplantation (HSCT) was not actively performed in elderly acute myeloid leukemia (AML) or myelodysplastic syndrome patients who are at a high-risk based on hematopoietic cell transplantation-specific comorbidity index (HCT-CI). The advent of reduced-intensity conditioning (RIC) regimens has made HSCT applicable in this population. However, the selection of appropriate conditioning is a major concern for the attending physician. The benefits of combination of treosulfan and fludarabine (Treo/Flu) have been confirmed through many clinical studies. Korean data on treosulfan-based conditioning regimen are scarce. METHODS: A retrospective study was conducted to compare the clinical outcomes of allogeneic HSCT using RIC between 13 patients receiving Treo/Flu and 39 receiving busulfan/fludarabine (Bu/Flu). RESULTS: In terms of conditioning-related complications, the frequency of ≥ grade 2 nausea or vomiting was significantly lower and the duration of symptoms was shorter in the Treo/Flu group than in the Bu/Flu group. The incidence of ≥ grade 2 mucositis tended to be lower in the Treo/Flu group. In the analysis of transplant outcomes, all events of acute graft versus host disease (GVHD) and ≥ grade 2 acute GVHD occurred more frequently in the Treo/Flu group. The frequency of Epstein-Barr virus reactivation was significantly higher in the Treo/Flu group (53.8% vs. 23.1%, P = 0.037). Non-relapse mortality (NRM) at 12 months was higher in the Treo/Flu group (30.8% vs. 7.7%, P = 0.035). Significant prognostic factors included disease type, especially secondary AML, disease status and high-risk based on HCT-CI, ≥ grade 2 acute GVHD, and cases requiring ≥ 2 immunosuppressive drugs for treating acute GVHD. In the comparison of survival outcomes according to conditioning regimen, the Bu/Flu group seemed to show better results than the Treo/Flu group (60% vs. 46.2%, P = 0.092 for overall survival; 56.4% vs. 38.5%, P = 0.193 for relapse-free survival). In additional analysis for only HCT-CI high-risk groups, there was no difference in transplant outcomes except that the Treo/Flu group tended to have a higher NRM within one year after transplantation. Survival outcomes of both groups were similar. CONCLUSION: This study suggests that Treo/Flu conditioning may be an alternative to Bu/Flu regimen in elderly patients with high-risk who are not suitable for standard conditioning.

Comprehensive molecular analysis to predict the efficacy of chemotherapy containing bevacizumab in patients with metastatic colorectal cancer.

Background: Although bevacizumab is an important treatment for metastatic colorectal cancer (CRC), not all patients with CRC benefit from it; in unselected patient populations, only modest survival benefits have been reported. Methods: We evaluated clinical outcomes in 110 patients using comprehensive molecular characterization to identify biomarkers for a response to bevacizumab-containing treatment. The molecular analysis comprised whole-exome sequencing, ribonucleic acid sequencing, and a methylation array on patient tissues. Results: Genomic and molecular characterization was successfully conducted in 103 patients. Six of 103 CRC samples were hypermutated, and none of the non-hypermutant tumors were microsatellite unstable. Among those 103 patients, 89 had adenocarcinoma (ADC), 15 were diagnosed with mucinous ADC, and six had signet-ring cell carcinoma (SRCC). Consensus molecular subtype (CMS) 2 was unique to ADC. Of the four SRCCs, two were CMS1, one was CMS4, and the other was CMS3. APC mutation status was a significantly enriched factor in responders to bevacizumab treatment. Fibroblast growth factor receptor (FGFR) 1/2 signaling was upregulated in non-responders, whereas cell cycle, transfer ribonucleic acid processing, nucleotide excision repair, and oxidative phosphorylation pathways were enriched in responders. In addition, IGF1 was differentially expressed in non-responders (log2 fold change = -1.43, p = 4.11 × 10-5, false discovery rate = 0.098), and FLT1 was highly methylated in non-responders (p = 7.55 × 10-3). When the molecular pathways were reanalyzed separately according to the backbone chemotherapy (FOLFOX vs. FOLFIRI), the significance of the molecular pathways varied according to the backbone chemotherapy. Conclusions: This study sought a subset of CRC patients with a distinct clinical response to chemotherapy containing bevacizumab. Our results need to be validated in a large group of homogenous patient cohort and examined according to the different chemotherapy backbones to create personalized therapeutic opportunities in CRC.

Pemetrexed and Erlotinib as a Salvage Treatment in Patients With Metastatic Biliary Tract Cancer Who Failed Gemcitabine-containing Chemotherapy: A Phase II Single-arm Prospective Study.

BACKGROUND/AIM: No standard treatment is currently recommended for advanced biliary tract cancer (BTC) after first-line therapy with gemcitabine plus cisplatin. We aimed to evaluate the efficacy and safety of a pemetrexed and erlotinib combination in patients with BTC previously treated with gemcitabine. PATIENTS AND METHODS: This phase II, open-label, single-arm study enrolled patients with BTC who had previously failed gemcitabine-based first-line chemotherapy. Patients were treated with pemetrexed as a 500 mg/m2 intravenous infusion on day 1 for three weeks and erlotinib 100 mg daily until disease progression or unacceptable toxicity. The primary endpoint was the overall response rate (ORR). RESULTS: The study enrolled 20 patients with BTC, including 12 (60%) with intrahepatic cholangiocarcinoma (IHCC), 3 (15%) with extrahepatic cholangiocarcinoma (EHCC), and 5 (25%) with gallbladder cancer (GBC). The ORR was 5%, and the disease control rate (DCR) was 55%. As of the cutoff point of March 31, 2023, the median progression-free survival (PFS) was 2.3 months [95% confidence interval (CI)=0.00-4.74] and the median overall survival (OS) was 5.6 months (95%CI=2.28-8.87). Patients with EHCC showed longer PFS and OS compared to patients with IHCC or GBC, but the differences were not significant. A baseline CEA greater than the upper normal limit was the only significant prognostic factor for a worse OS rate. The only treatment-related adverse event (TRAE) with severity grade ≥3 was anemia (5%). CONCLUSION: Salvage chemotherapy with pemetrexed plus erlotinib was well-tolerated and showed marginal clinical activity in BTC patients after failure to gemcitabine-based chemotherapy.

The Optimal Tumor Mutational Burden Cutoff Value as a Novel Marker for Predicting the Efficacy of Programmed Cell Death-1 Checkpoint Inhibitors in Advanced Gastric Cancer.

PURPOSE: The optimal tumor mutational burden (TMB) value for predicting treatment response to programmed cell death-1 (PD-1) checkpoint inhibitors in advanced gastric cancer (AGC) remains unclear. We aimed to investigate the optimal TMB cutoff value that could predict the efficacy of PD-1 checkpoint inhibitors in AGC. MATERIALS AND METHODS: Patients with AGC who received pembrolizumab or nivolumab between October 1, 2020, and July 27, 2021, at Samsung Medical Center in Korea were retrospectively analyzed. The TMB levels were measured using a next-generation sequencing assay. Based on receiver operating characteristic curve analysis, the TMB cutoff value was determined. RESULTS: A total 53 patients were analyzed. The TMB cutoff value for predicting the overall response rate (ORR) to PD-1 checkpoint inhibitors was defined as 13.31 mutations per megabase (mt/Mb) with 56% sensitivity and 95% specificity. Based on this definition, 7 (13.2%) patients were TMB-high (TMB-H). The ORR differed between the TMB-low (TMB-L) and TMB-H (8.7% vs. 71.4%, P=0.001). The progression-free survival and overall survival (OS) for 53 patients were 1.93 (95% confidence interval [CI], 1.600-2.268) and 4.26 months (95% CI, 2.992-5.532). The median OS was longer in the TMB-H (20.8 months; 95% CI, 2.292-39.281) than in the TMB-L (3.31 months; 95% CI, 1.604-5.019; P=0.049). CONCLUSIONS: The TMB cutoff value for predicting treatment response in AGC patients who received PD-1 checkpoint inhibitor monotherapy as salvage treatment was 13.31 mt/Mb. When applying the programmed death ligand-1 status to TMB-H, patients who would benefit from PD-1 checkpoint inhibitors can be selected.

Eight-Month Follow-up After the Third Dose of BNT162b2 Vaccine in Healthcare Workers: The Question of a Fourth Dose.

BACKGROUND: A fourth dose of vaccination is known to help reduce the severity and mortality rate of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The South Korean vaccination guidelines for the fourth dose do not include healthcare workers (HCWs) as priority candidates. We investigated the necessity of the fourth dose in South Korean HCWs based on an 8-month follow-up period after the third vaccination. METHODS: Changes in the surrogate virus neutralization test (sVNT) inhibition (%) score were measured at one month, four months and eight months after the third vaccination. The sVNT values were analyzed between infected and uninfected groups, and their trajectories were compared. RESULTS: A total of 43 HCWs were enrolled in this study. In total, 28 cases (65.1%) were confirmed to be infected with SARS-CoV-2 (presumed omicron variant), and all had mild symptoms. Meanwhile, 22 cases (78.6%) were infected within four months of the third dose (median, 97.5 days). Eight months after the third dose, the SARS-CoV-2 (presumed omicron variant)-infected group showed significantly higher sVNT inhibition than that in the uninfected group (91.3% vs. 30.7%; P < 0.001). The antibody response due to hybrid immunity, provided by a combination of infection and vaccination, was maintained at sufficient levels for more than four months. CONCLUSION: For HCWs who had coronavirus disease 2019 infection after completing a third vaccination, a sufficient antibody response was maintained until eight months after the third dose. The recommendation of the fourth dose may not be prioritized in subjects with hybrid immunity.

Effects of Omicron Infection and Changes in Serum Antibody Response to Wild-Type, Delta, and Omicron After a Booster Dose With BNT163b2 Vaccine in Korean Healthcare Workers.

BACKGROUND: Although the primary vaccine coverage rate for coronavirus disease 2019 (COVID-19) in South Korea has exceeded 80%, the coronavirus continues to spread, with reports of a rapid decline in vaccine effectiveness. South Korea is administering booster shots despite concerns about the effectiveness of the existing vaccine. METHODS: Neutralizing antibody inhibition scores were evaluated in two cohorts after the booster dose. For the first cohort, neutralizing activity against the wild-type, delta, and omicron variants after the booster dose was evaluated. For the second cohort, we assessed the difference in neutralizing activity between the omicron infected and uninfected groups after booster vaccination. We also compared the effectiveness and adverse events (AEs) between homologous and heterologous booster doses for BNT162b2 or ChAdOx1 vaccines. RESULTS: A total of 105 healthcare workers (HCWs) that were additionally vaccinated with BNT162b2 at Soonchunhyang University Bucheon Hospital were enrolled in this study. Significantly higher surrogate virus neutralization test (sVNT) inhibition (%) was observed for the wild-type and delta variants compared to sVNT (%) for the omicron after the booster dose (97%, 98% vs. 75%; P < 0.001). No significant difference in the neutralizing antibody inhibition score was found between variants in the BNT/BNT/BNT group (n = 48) and the ChA/ChA/BNT group (n = 57). Total AEs were not significantly different between the ChA/ChA/BNT group (85.96%) and the BNT/BNT group (95.83%; P = 0.11). In the second cohort with 58 HCWs, markedly higher sVNT inhibition to omicron was observed in the omicron-infected group (95.13%) compared to the uninfected group (mean of 48.44%; P < 0.001) after four months of the booster dose. In 41 HCWs (39.0%) infected with the omicron variant, no difference in immunogenicity, AEs, or effectiveness between homogeneous and heterogeneous boosters was observed. CONCLUSION: Booster vaccination with BNT162b2 was significantly less effective for the neutralizing antibody responses to omicron variant compared to the wild-type or delta variant in healthy population. Humoral immunogenicity was sustained significantly high after 4 months of booster vaccine in the infected population after booster vaccination. Further studies are needed to understand the characteristics of immunogenicity in these populations.

Comparison of antibody response to coronavirus disease 2019 vaccination between patients with solid or hematologic cancer patients undergoing chemotherapy.

AIM: This study examined the serum antibody response of coronavirus disease 2019 (COVID-19) vaccines in solid and hematologic cancer patients undergoing chemotherapy. Levels of various inflammatory cytokines/chemokines after full vaccination were analyzed. METHODS: Forty-eight patients with solid cancer and 37 with hematologic malignancy who got fully vaccinated either with severe acute respiratory syndrome coronavirus 2 messenger RNA (mRNA) or vector vaccines or their combination were included. After consecutively collecting blood, immunogenicity was assessed by surrogate virus neutralization test (sVNT), and cytokine/chemokines were evaluated by Meso Scale Discovery assay. RESULTS: Seropositivity and protective immune response were lower in patients with hematologic cancer compared to those with solid cancers, regardless of vaccine type. Significantly lower sVNT inhibition was observed in patients with hematologic cancer (mean [SD] 45.30 [40.27] %) than in those with solid cancer (mean [SD] 61.78 [34.79] %) (p = 0.047). Heterologous vector/mRNA vaccination was independently and most markedly associated with a higher sVNT inhibition score (p < 0.05), followed by homologous mRNA vaccination. The mean serum levels of tumor necrosis factor α, macrophage inflammatory protein (MIP)-1α, and MIP-1ß were significantly higher in patients with hematologic cancers compared to those with solid cancers after the full vaccination. In 36 patients who received an additional booster shot, 29 demonstrated increased antibody titer in terms of mean sVNT (%) (40.80 and 75.21, respectively, before and after the additional dose, p < 0.001). CONCLUSION: Hematologic cancer patients receiving chemotherapy tended to respond poorly to both COVID-19 mRNA and vector vaccines and had a significantly lower antibody titer compared to those with solid cancers.

Clinical Experience of Allogeneic Hematopoietic Stem Cell Transplantation in Elderly Patients Aged 60 Years and Older in South Korea.

PURPOSE: The purpose of this study is to share our outcomes and experiences on allogeneic hematopoietic stem cell transplantation (HSCT) in elderly patients aged 60 years and older with myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML) in South Korea, and to compare them with other studies. MATERIALS AND METHODS: We analyzed the clinical outcomes of 116 patients with AML or MDS aged 60 years and older who underwent allogeneic HSCT. We also analyzed which pretreatment factors affect the overall survival (OS) after allogeneic HSCT. RESULTS: Neutrophil and platelet engraftment were achieved at median day +11 [interquartile range (IQR) 10-15] and +14 (IQR 11-19), respectively. A complete donor chimerism was confirmed in 65 (56.0%) patients at 3 weeks and in 63 (54.3%) patients at 3 months after HSCT. The estimated incidence of grade II-IV acute graft-versus-host disease (GVHD) at day 100 was 13.7%. The estimated incidence of chronic GVHD at 2 years was 38.8%. Within a median follow-up of 14 months after HSCT, OS was 64% at 1 year and 55% at 2 years, and non-relapse mortality (NRM) was 20% at 1 year and 28% at 2 years. Multivariate analysis revealed that male sex and Hematopoietic Cell Transplantation-Specific Comorbidity Index ≥3 were associated with poor OS. CONCLUSION: This study showed that allogeneic HSCT in elderly adults aged 60 and older can be performed with successful engraftment and acceptable NRM and OS are expected given the generally known survival of patients with higher risk MDS and poor risk AML.