DNA mismatch repair deficiency and outcomes of patients with locally advanced gastric cancer treated with preoperative docetaxel, oxaliplatin, and S-1 plus surgery and postoperative S-1 or surgery plus postoperative S-1: a sub-analysis of the phase 3 PRODIGY trial.

BACKGROUND: The benefit of adjuvant chemotherapy for locally advanced gastric cancer (LAGC) patients with DNA mismatch repair (MMR) deficiency (D-MMR) is controversial due to concerns about its potential detrimental effect. The PRODIGY trial showed the survival benefit of adding preoperative docetaxel, oxaliplatin, and S-1 (DOS) to surgery plus postoperative S-1 for LAGC patients. In this sub-analysis, we evaluated the benefit of preoperative DOS according to MMR status. METHODS: Among patients enrolled in the PRODIGY trial treated with either preoperative DOS followed by surgery and postoperative S-1 (CSC arm), or surgery and postoperative S-1 (SC arm) at Asan Medical Center (n = 249), those in the full analysis set with available tissue to assess MMR status were included in the present analysis. RESULTS: A total of 231 patients (CSC arm, n = 108; SC arm, n = 123) were included (median age, 58 years [range, 27-75]), and 21 patients (CSC arm, n = 8 [7.4%]; SC arm, n = 13 [10.6%]) had D-MMR tumors. Progression-free survival and overall survival tended to be superior in the CSC arm than in the SC arm among D-MMR patients (HR 0.48 [95% CI 0.09-2.50]; log-rank P = 0.37 and HR 0.55 [95% CI 0.11-2.86]; log-rank P = 0.46, respectively), as well as among proficient MMR (P-MMR) patients (HR 0.68 [95% CI 0.46-1.03]; log-rank P = 0.07 and HR 0.75 [95% CI 0.49-1.14]; log-rank P = 0.17, respectively). CONCLUSION: Preoperative DOS followed by surgery and postoperative S-1 may be considered a treatment option for LAGC patients regardless of MMR status.

Insertion-deletion rate is a qualitative aspect of the tumor mutation burden associated with the clinical outcomes of gastric cancer patients treated with nivolumab.

BACKGROUND: We aimed to investigate the clinical implications of the tumor mutation burden (TMB) and insertion-deletion (indel) rate in gastric cancer patients treated with nivolumab. METHODS: A total of 105 patients with advanced gastric cancer who were treated with nivolumab as third or later line of therapy were included as the study population. The indel rate was defined as the proportion of indels making up the TMB. RESULTS: The median age was 58 (32-78 years), and 65 (61.9%) were men. Patients with TMB > 18.03/Mb showed superior progression-free survival (PFS) and overall survival (OS) compared to those with TMB ≤ 18.03/Mb. Patients with a high indel rate (> 40%) had a favorable PFS and OS compared to those with a lower indel rate (≤ 40%) (P = 0.009 and P = 0.007, respectively). The association between a high indel rate and favorable PFS and OS was prominent in a subgroup with TMB > 18.03/Mb (P < 0.001 and P = 0.007 for PFS and OS, respectively), but not in that with TMB ≤ 18.03/Mb. All five patients with deficient-MMR fell into the category of 'TMB > 18.03/Mb with an indel rate of > 40%. TMB ≥ 18.03/Mb with an indel rate of > 40% was independently associated with a favorable PFS (hazard ratio [HR] 0.07, P = 0.012) and OS (HR 0.09, P = 0.023). CONCLUSION: TMB and indel rate should be jointly considered to better predict survival outcomes of gastric cancer patients treated with nivolumab. Our findings deserve further investigation and validation in future studies.

Association between HER2 heterogeneity and clinical outcomes of HER2-positive gastric cancer patients treated with trastuzumab.

BACKGROUND: The GASTHER1 study showed that re-evaluation of HER2 status rescued 8% of HER2-positive gastric cancer (GC) patients with initially HER2-negative GC. Since rescued HER2 positivity represents HER2 heterogeneity, we aimed to investigate this in a larger cohort with longer follow-up duration. METHODS: Data of 153 HER2-positive advanced GC patients who received first-line trastuzumab-based chemotherapy were analyzed. Repeat endoscopic biopsy was performed in patients with initially HER2-negative GC. Survival outcomes were analyzed according to the immunohistochemistry (IHC) score (IHC 2+ /in situ hybridization [ISH] + vs IHC 3+), HER2 status (initially vs rescued HER2 positive), and H-score. RESULTS: IHC 2+ /ISH + patients showed worse progression-free survival (PFS) and overall survival (OS) than those with IHC 3+ (p < 0.05). Rescued HER2-positive patients showed worse PFS and OS than initially HER2-positive patients (p < 0.05). Although survival outcomes were comparable according to HER2 status in IHC 2+ /ISH + patients, initially HER2-positive patients showed more favorable PFS and OS than rescued HER2-positive patients (p < 0.05) among those with IHC 3+ . Among the subgroups determined by HER2 status and IHC score, the initially IHC 3+ subgroup had the highest H-score. The low H-score group (H-score ≤ 210) had significantly worse survival outcomes than the high H-score group (H-score > 210) (p < 0.05). An H-score of ≤ 210 was independently associated with shorter OS (HR = 1.54, 95% CI 1.02-2.31, p = 0.04). CONCLUSIONS: Rescued HER2-positive patients showed worse clinical outcomes than initially HER2-positive patients, especially those with IHC 3+ . This finding highlights the impact of HER2 heterogeneity, which can be quantified indirectly as an H-score.

Clinical implications of neutrophil-to-lymphocyte ratio and MDSC kinetics in gastric cancer patients treated with ramucirumab plus paclitaxel.

OBJECTIVE: We aimed to investigate the prognostic value of neutrophil-to-lymphocyte ratio (NLR) and myeloid-derived suppressor cells (MDSCs) in gastric cancer patients treated with second-line ramucirumab plus paclitaxel. METHODS: A total of 116 patients with advanced or metastatic gastric cancer who receive ramucirumab plus paclitaxel were prospectively enrolled. Fresh blood samples were collected before and after treatment, and flow cytometry was performed to assess the proportions of monocytic (mMDSCs) and granulocytic MDSCs (gMDSCs). RESULTS: Median age was 58 years and 71 (61.2%) patients were male. A baseline NLR≥2.94 was associated with significantly poorer progression-free survival (PFS) and overall survival (OS) vs. an NLR<2.94 (P=0.011 and P=0.002, respectively). In multivariate analysis, an NLR≥2.94 was independently associated with poorer PFS [hazard ratio (HR)=1.58; 95% confidence interval (95% CI): 1.01-2.49, P=0.046] and OS (HR=1.77; 95% CI: 1.04-3.04, P=0.036). While mMDSC counts did not significantly change following two cycles of therapy (P=0.530), gMDSC counts decreased significantly after two treatment cycles (P=0.025) but tended to increase in patients with progressive disease after two treatment cycles (P=0.098). A progressive increase in gMDSC counts (≥44%) was associated with a significantly shorter PFS and OSvs. a gMDSC count increase <44% (P=0.001 and P=0.003, respectively). CONCLUSIONS: The baseline NLR may help guide clinical decisions during ramucirumab plus paclitaxel therapy for gastric cancer. Our gMDSC kinetics data warrant further clinical validation and mechanistic investigation.

GASTric Cancer HER2 Re-Assessment Study 2 (GASTHER2): HER2 Re-assessment for Initially HER2-Negative Advanced Gastric Cancer Patients after Progression on First-Line Treatment.

PURPOSE: Heterogeneous human epidermal growth factor receptor 2 (HER2) overexpression in gastric cancer may lead to a misdiagnosis of HER2 status. Accurate assessment of HER2 status is essential for optimal treatment as novel HER2-directed agents are being investigated in various clinical settings. We evaluated the usefulness of HER2 re-assessment following progression on first-line treatment in initially HER2-negative advanced gastric cancer (AGC) patients. MATERIALS AND METHODS: We enrolled 177 patients with baseline HER2-negative AGC and performed HER2 re-assessment after progression on first-line treatment from February 2012 to June 2016 at Asan Medical Center, Seoul, Korea. The re-assessed HER2 status was analyzed with baseline HER2 status and clinical characteristics. RESULTS: The median age was 54 years (range, 24 to 80 years), and 123 patients (69.5%) were men. Seven patients (4.0%) were HER2-positive on the re-assessment. Patients with baseline HER2 negativity confirmed by a single test (n=100) had a higher HER2-positive re-assessment rate compared to those who had repeated baseline testing (n=77) (5.0% vs. 2.6%). Among the patients with single baseline HER2 testing, the rate was higher in patients with baseline HER2 immunohistochemistry (IHC) 1+ compared to those with IHC 0 (13.4% vs. 3.6%). CONCLUSION: Overall, 4.0% of patients with baseline HER2-negative AGC were HER2-positive on re-assessment, and the HER2-positive re-assessment rate was higher among patients who had a single test at baseline. HER2 re assessment may be considered for initially HER2-negative patients to determine their eligibility for HER2-directed therapy, particularly if their HER2 negativity was determined by a single test, especially if they had a single baseline HER2 IHC 1+ test.

New prognostic model for patients with advanced gastric cancer: Fluoropyrimidine/platinum doublet for first-line chemotherapy.

BACKGROUND: New prognostic factors have been reported in patients with metastatic or recurrent gastric cancer (MRGC), necessitating modifications to the previous prognostic model. AIM: To develop a new model, MRGC patients who received fluoropyrimidines/ platinum doublet chemotherapy between 2008 and 2015 were analyzed. METHODS: A total of 1883 patients was divided into a training set (n = 937) and an independent validation set (n = 946). RESULTS: Multivariate analysis showed that the following six factors were associated with poor overall survival (OS) in the training set: Eastern Cooperative Oncology Group performance score ≥ 2 and bone metastasis (2 points each), peritoneal metastasis, high alkaline phosphatase level, low albumin level, and high neutrophil-lymphocyte ratio (1 point each). A prognostic model was developed by stratifying patients into good (0-1 point), moderate (2-3 points), and poor (≥ 4 points) risk groups. In the validation set, the median OS of the three risk groups was 15.8, 10.1, and 5.7 mo, respectively, and those differences were significant (P < 0.001). CONCLUSION: We identified six factors readily measured in clinical practice that are predictive of poor prognosis in patients with MRGC. The new model is simpler than the old and more easily predicts OS.

Trends in Chemotherapy Patterns and Survival of Patients with Advanced Gastric Cancer over a 16-Year Period: Impact of Anti-HER2-Targeted Agent in the Real-World Setting.

PURPOSE: This study aimed to evaluate the survivals of patients with metastatic or recurrent gastric cancer (MRGC) over a period of 16 years and to investigate the recent changes in chemotherapy patterns. MATERIALS AND METHODS: A total of 5,384 patients who received chemotherapy for MRGC between 2000 and 2015 were analyzed. The analysis focused on a comparison of the first-line chemotherapy between four periods: 2000-2003 (period 1), 2004-2007 (period 2), 2008-2011 (period 3), and 2012-2015 (period 4). RESULTS: There were 880 patients (16%) in period 1, 1,573 (29%) in period 2, 1,435 (27%) in period 3, and 1,496 (28%) in period 4. Cytotoxic doublet-based therapy was the most commonly used (78%) first-line chemotherapy, and the combination of trastuzumab and doublet chemotherapy was provided to 288 patients. The overall survival (OS) rates at 12 and 24 months were steadily improved as follows: 39.2% and 14.6% in period 1, 43.5% and 17.6% in period 2, 50.3% and 20.6% in period 3, and 51.7% and 24.1% in period 4, respectively (p < 0.001). Among the patients who received the doublet-based chemotherapy, the median OS of those who received trastuzumab was 18.0 months (95% confidence interval [CI], 15.5 to 20.6), while that of those who received other doublet therapies was 11.2 months (95% CI, 10.8 to 11.6). CONCLUSION: The OS was improved over time with advancements in chemotherapy, particularly the introduction of the anti-HER2-targeted agent, which contributed to the increase in the number of long-term survivors and established the superiority of OS for the treatment of MRGC.