Chang Gon Kim

Effects of microsatellite instability on recurrence patterns and outcomes in colorectal cancers

Background:Among colorectal cancers (CRCs), high-frequency microsatellite instability (MSI-H) is associated with a better prognosis, compared with low-frequency MSI or microsatellite stability (MSI-L/MSS). However, it is unclear whether MSI affects the prognosis of recurrent CRCs.Methods:This study included 2940 patients with stage I–III CRC who underwent complete resection. The associations of MSI status with recurrence patterns, disease-free survival (DFS), overall survival from diagnosis to death (OS1), and overall survival from recurrence to death (OS2) were analysed.Results:A total of 261 patients (8.9%) had MSI-H CRC. Patients with MSI-H CRC had better DFS, compared to patients with MSI-L/MSS CRC (hazard ratio (HR): 0.619, P<0.001). High-frequency microsatellite instability CRC was associated with more frequent local recurrence (30.0% vs 12.0%, P=0.032) or peritoneal metastasis (40.0% vs 12.3%, P=0.003), and less frequent lung (10.0% vs 42.5%, P=0.004) or liver metastases (15.0% vs 44.7%, P=0.01). Recurrent MSI-H CRC was associated with worse OS1 (HR: 1.363, P=0.035) and OS2 (HR: 2.667, P<0.001). An analysis of patients with colon cancer yielded similar results.Conclusions:Recurrence patterns differed between MSI-H CRC and MSI-L/MSS CRC, and recurrent MSI-H CRCs had a worse prognosis.

YAP-Induced PD-L1 Expression Drives Immune Evasion in BRAFi-Resistant Melanoma

Transcription factor YAP increases PD-L1 expression in BRAF inhibitor-resistant melanoma cells, promoting their direct evasion of T-cell killing. Inhibition of this YAP-orchestrated interplay between inhibitor resistance and immune evasion could improve the treatment of BRAF-mutant melanoma patients. Activation of YAP, a Hippo pathway effector, is an important resistance mechanism to BRAF inhibitor (BRAFi) in melanoma. Emerging evidence also suggests that YAP is involved in suppression of the antitumor immune response. However, the potential direct impact of YAP activity on cytotoxic T-cell immune responses has not been explored yet. Here, we show that BRAFi-resistant melanoma cells evade CD8+ T-cell immune responses in a PD-L1–dependent manner by activating YAP, which synchronously supports melanoma cell survival upon BRAF inhibition. PD-L1 expression is elevated in BRAFi-resistant melanoma cells, in which YAP is robustly activated, and YAP knockdown decreases PD-L1 expression. In addition, constitutively active YAP (YAP-5SA) increases PD-L1 expression by binding to an upstream enhancer of the PD-L1 gene and potentiating its transcription. Both BRAFi-resistant and YAP-5SA–expressing melanoma cells suppress the cytotoxic function and cytokine production of Melan-A–specific CD8+ T cells, whereas anti–PD-1 antibody reverses the YAP-mediated T-cell suppression. Moreover, nuclear enrichment of YAP in clinical melanoma samples correlates with increased PD-L1 expression. Our findings show that YAP directly mediates evasion of cytotoxic T-cell immune responses in BRAFi-resistant melanoma cells by upregulating PD-L1, and targeting of YAP-mediated immune evasion may improve prognosis of melanoma patients. Cancer Immunol Res; 6(3); 255–66. ©2018 AACR.

Detection of activating and acquired resistant mutation in plasma from EGFR-mutated NSCLC patients by peptide nucleic acid (PNA) clamping-assisted fluorescence melting curve analysis

This study was designed to prospectively examine whether peptide nucleic acid clamping-assisted fluorescence melting curve analysis (PANAMutyper™) is feasible for the detection of activating and acquired resistant epidermal growth factor receptor (EGFR) mutation in plasma. Patients with non-small cell lung cancer harboring activating EGFR mutations who were scheduled to undergo EGFR-tyrosine kinase inhibitors (EGFR-TKIs) were enrolled between September 2011 and March 2015. A total of 102 patients with EGFR-mutated lung cancer were enrolled, 53 had available plasma samples at disease progression, and 28 underwent serial plasma sampling during EGFR-TKI treatment. EGFR-TKI-sensitizing and T790M mutations were detected in the plasma of 68.6% (70/102) at baseline and 30.2% (16/53) at disease progression, respectively. The concordance rates for matched tissue and plasma samples were 80.4% and 90.2% for E19del and L858R mutations at baseline and 56.3% for T790M mutation at disease progression. The sustained presence of plasma EGFR mutations four weeks after EGFR-TKI predicted a poor objective response rate (30.0% vs. 87.5%, P = 0.025), as well as worse progression-free survival (hazard ratio [HR], 4.381) and overall survival (HR, 5.475). Longitudinal analysis could detect T790M mutations earlier than disease progression based on imaging study (median time from appearance of T790M in plasma samples to progression at imaging scan, 103 days). In conclusion, PANAMutyper™ is reliable for detecting activating and acquired resistant EGFR mutation in plasma, and predicts responses to EGFR-TKI via longitudinal monitoring of EGFR mutation during treatment.This study was designed to prospectively examine whether peptide nucleic acid clamping-assisted fluorescence melting curve analysis (PANAMutyper™) is feasible for the detection of activating and acquired resistant epidermal growth factor receptor (EGFR) mutation in plasma. Patients with non-small cell lung cancer harboring activating EGFR mutations who were scheduled to undergo EGFR-tyrosine kinase inhibitors (EGFR-TKIs) were enrolled between September 2011 and March 2015. A total of 102 patients with EGFR-mutated lung cancer were enrolled, 53 had available plasma samples at disease progression, and 28 underwent serial plasma sampling during EGFR-TKI treatment. EGFR-TKI-sensitizing and T790M mutations were detected in the plasma of 68.6% (70/102) at baseline and 30.2% (16/53) at disease progression, respectively. The concordance rates for matched tissue and plasma samples were 80.4% and 90.2% for E19del and L858R mutations at baseline and 56.3% for T790M mutation at disease progression. The sustained presence of plasma EGFR mutations four weeks after EGFR-TKI predicted a poor objective response rate (30.0% vs. 87.5%, P = 0.025), as well as worse progression-free survival (hazard ratio [HR], 4.381) and overall survival (HR, 5.475). Longitudinal analysis could detect T790M mutations earlier than disease progression based on imaging study (median time from appearance of T790M in plasma samples to progression at imaging scan, 103 days). In conclusion, PANAMutyper™ is reliable for detecting activating and acquired resistant EGFR mutation in plasma, and predicts responses to EGFR-TKI via longitudinal monitoring of EGFR mutation during treatment.

Role of adjuvant chemotherapy in locally advanced rectal cancer with ypT0-3N0 after preoperative chemoradiation therapy and surgery

BackgroundWe aimed to explore the clinical benefit of adjuvant chemotherapy (AC) with fluoropyrimidine in patients with ypT0-3N0 rectal cancer after preoperative chemoradiation therapy (CRT) followed by total mesorectal excision (TME).MethodsPatients with ypT0-3N0 rectal cancer after preoperative CRT and TME were included using prospectively collected tumor registry cohort between January 2001 and December 2013. Patients were categorized into two groups according to the receipt of AC. Disease-free survival (DFS) and overall survival (OS) were compared between the adjuvant and observation groups. To control for potential confounding factors, we also calculated propensity scores and performed propensity score-matched analysis for DFS and OS.ResultsOf the 339 evaluated patients, 87 patients (25.7%) did not receive AC. There were no differences in DFS (hazard ratio [HR], 0.921; 95% confidence interval [CI], 0.562–1.507; P = 0.742) and OS (HR, 0.835; 95% CI, 0.423–1.648; P = 0.603) between the adjuvant and observation groups. After propensity score matching, DFS (HR, 1.129; 95% CI, 0.626–2.035; P = 0.688) and OS (HR, 1.200; 95% CI, 0.539–2.669; P = 0.655) did not differ between the adjuvant and observation groups. Advanced T stage and positive resection margin were independently associated with inferior DFS and OS on multivariate analysis.ConclusionsAC did not improve DFS and OS for patients with ypT0-3N0 rectal cancer after preoperative CRT followed by TME in this cohort study. The confirmative role of AC in locally advanced rectal cancer should be evaluated in prospective randomized trials with a larger sample size.

Incidence of Febrile Neutropenia in Korean Female Breast Cancer Patients Receiving Preoperative or Postoperative Doxorubicin/Cyclophosphamide Followed by Docetaxel Chemotherapy

Purpose Doxorubicin/cyclophosphamide followed by docetaxel chemotherapy (AC-D) is an intermediate risk factor (incidence of 10%–20%) for febrile neutropenia (FN) in breast cancer. However, the reported incidence of FN while using this regimen was obtained mostly from Western breast cancer patients, with little data available from Asian patients. This study aimed to assess the incidence of FN in Korean breast cancer patients and to describe clinical variables related to FN. Methods From September 2010 to February 2013, data from the Yonsei Cancer Center registry of breast cancer patients who received neoadjuvant or adjuvant chemotherapy with four cycles of AC-D (60 mg/m2 doxorubicin, 600 mg/m2 cyclophosphamide every 3 weeks for four cycles followed by 75 mg/m2 or 100 mg/m2 docetaxel every 3 weeks for four cycles) were analyzed. The incidence of FN, FN associated complications, dose reduction/delays, and relative dose intensity (RDI) were investigated. Results Among the 254 patients reported to the registry, the FN incidence after AC-D chemotherapy was 29.5% (75/254), consisting of 25.2% (64/254) events during AC and 4.7% (12/254) during docetaxel chemotherapy. Dose reductions, delays, and RDI less than 85.0% during AC were observed in 16.5% (42/254), 19.5% (47/254), and 11.0% (28/254) of patients, respectively. Patients with FN events frequently experienced dose reduction/delays, which eventually led to a decreased RDI. Conclusion The incidence of FN during AC-D neoadjuvant or adjuvant chemotherapy was higher than expected in Korean breast cancer patients. Whether these patients should be classified as a high-risk group for FN warrants future prospective studies.

Effect of combined anti-PD-1 and temozolomide therapy in glioblastoma

ABSTRACT Background: Although programmed death-1 (PD-1) blockade is effective in treating several types of cancer, the efficacy of this agent in glioblastoma (GBM) is largely unknown. Methods: We evaluated therapeutic effects of anti-PD-1, temozolomide (TMZ), and their combination in an orthotopic murine GBM model. The phenotype, number, and composition of lymphocytes were evaluated using flow cytometry. Transcriptional profiles of tumor tissues were analyzed using microarrays. Generation of antitumor immunological memory was investigated upon rechallenge. Results: Combined treatment with anti-PD-1 and TMZ yielded synergistic antitumor efficacy in the presence of donor-originated PD-1+CD8+ T cells in vitro, necessitating in vivo validation. Whereas TMZ did not rescue GBM-implanted mice, anti-PD-1 completely eradicated GBM in 44.4% of mice, and combination of anti-PD-1 and TMZ in all mice. Anti-PD-1 significantly increased the number of tumor-infiltrating lymhpocytes (TILs), and reduced frequencies of exhausted T cells and regulatory T cells. However, combining TMZ with anti-PD-1 significantly decreased the number of TILs, which was also observed with TMZ treatment alone. A transcriptome analysis of tumor tissues revealed that anti-PD-1 monotherapy perturbed immune-related genes, distinctly with combined therapy. Upon rechallenge, tumor growth was not observed in mice cured by anti-PD-1 monotherapy, whereas tumors regrew in the combination group. Furthermore, an analysis of peripheral blood revealed that antitumor memory T cells were generated in mice cured by anti-PD-1 monotherapy, not in the combination group. Conclusion: PD-1 blockade induces long-term therapeutic response, and combination with TMZ further enhances antitumor efficacy. However, immunological memory is provoked by anti-PD-1 monotherapy, not by combined therapy.

Prognoses and Clinical Outcomes of Primary and Recurrent Uveal Melanoma

Purpose Uveal melanoma has a very poor prognosis despite successful local primary tumor treatment. In this study, we investigated prognostic factors that more accurately reflected the likelihood of recurrence and survival and delineated a prognostic model that could effectively identify different risk groups based on initial clinical parameters. Materials and Methods Prognostic factors associated with distant recurrence, recurrence-free survival (RFS), progression-free survival, and overall survival from distant recurrence to death (OS2) were analyzed in 226 patients with stage I-III uveal melanoma who underwent primary local therapy. Results Forty-nine patients (21.7%) had distant recurrences, which occurred most frequently in the liver (87.7%). In a multivariate analysis, local radiotherapy improved RFS among patients with multiple recurrence risk factors relative to excision (not reached vs. 19.0 months, p=0.004). Patients with BRCA1-associated protein-1 (BAP1)‒negative primary tumors showed a longer RFS duration after primary treatments, while those with BAP1-negative metastatic tissues had a shorter OS2 compared to those with BAP1-positive tumors, both not statistically insignificance (RFS: not reached vs. 82.0 months, p=0.258; OS2: 15.7 vs. 24.4 months, p=0.216). Male sex (hazard ratio [HR], 3.79; p=0.012), a short RFS (HR, 4.89; p=0.014), and a largest metastatic tumor linear diameter ≥ 45 mm (HR, 5.48; p=0.017) were found to correlate with worse post-recurrence survival. Conclusion Risk factors could be used to classify uveal melanoma cases and subsequently direct individual treatment strategies. Furthermore, metastasectomy appears to contribute to improved survival outcomes.