Comparison of perioperative and histopathologic outcomes among neoadjuvant treatment strategies for locoregional gastric cancer.

BACKGROUND AND OBJECTIVES: Neoadjuvant chemotherapy (NAC) and chemoradiation (NCRT) have demonstrated improved survival for gastric cancer. However, the optimal neoadjuvant treatment remains unclear. We sought to evaluate perioperative and histopathologic outcomes among neoadjuvant treatments for locoregional gastric cancer. METHODS: The National Cancer Database queried patients who received NAC or NCRT followed by resection for T2-T4 and/or node-positive gastric cancer (2006-2018). Logistic and Poisson regression assessed perioperative (30-day readmission, 30- and 90-day mortality, length of stay [LOS]) and histopathologic outcomes (pathologic complete response [PCR], margin status, and negative pathologic lymph nodes [ypN0]). Kaplan-Meier methods and Cox regression assessed overall survival (OS). RESULTS: Of 9831 patients, 4221 (42.9%) received NAC and 5610 (57.1%) NCRT. There were no differences in perioperative outcomes, apart from patients treated with NCRT exhibiting increased LOS (incidence rate ratio 1.09, 95% confidence interval [CI] 1.03-1.16). Patients who received NCRT were more likely to achieve PCR, margin-negative resection, and ypN0 (all p < 0.05). Median OS was 36.8 months for NAC and 33.6 months for NCRT (p < 0.001). NCRT independently predicted worse OS (vs. NAC, hazard ratio 1.10, 95% CI 1.03-1.18). CONCLUSION: NCRT was associated with better histologic tumor response although NAC was associated with improved OS. Better understanding prognostication through histologic assessment following neoadjuvant therapy is needed.

The inaccuracies of gastric adenocarcinoma clinical staging and its predictive factors.

INTRODUCTION: Accurate clinical staging (CS) of gastric adenocarcinoma is important to guide treatment planning. Our objectives were to (1) assess clinical to pathologic stage migration patterns for patients with gastric adenocarcinoma, (2) identify factors associated with inaccurate CS, and (3) evaluate the association of understaging with survival. METHODS: The National Cancer Database was queried for patients who underwent upfront resection for stage I-III gastric adenocarcinoma. Multivariable logistic regression was used to detect factors associated with inaccurate understaging. Kaplan-Meier analyses and cox proportional hazards regression were performed to assess overall survival (OS) for patients with inaccurate CS. RESULTS: Of 14 425 analyzed patients, 5781 (40.1%) patients were inaccurately staged. Factors associated with understaging included treatment at a Comprehensive Community Cancer Program, presence of lymphovascular invasion, moderate to poor differentiation, large tumor size, and T2 disease. Based on overall CS, median OS was 51.0 months for accurately staged patients and 29.5 months for understaged patients (<0.001). CONCLUSION: Clinical T-category, large tumor size, and worse histologic features lead to inaccurate CS for gastric adenocarcinoma, impacting OS. Improvements to staging parameters and diagnostic modalities focusing on these factors may improve prognostication.

Characterization of human T lymphocytes engineered to express interleukin-15 and herpes simplex virus-thymidine kinase.

INTRODUCTION: Preclinical studies have demonstrated that tumor-reactive T cells expressing the interleukin (IL)-15 transgene had enhanced activity. Gene therapy strategies using IL-15 should include a safety mechanism in anticipation of possible adverse effects because IL-15 overexpression has been implicated in autoimmune disorders and may be involved in the pathogenesis of some leukemias. We developed a retroviral vector carrying both IL-15 and the herpes simplex virus-thymidine kinase (HSV-TK) suicide gene and characterized its application in the transduction of human T lymphocytes. METHODS: A retroviral vector carrying IL-15 and HSV-TK genes was optimized for the transduction of human T lymphocytes. IL-15 production was measured by enzyme-linked immunosorbent assay. Thymidine incorporation and cell viability assays were used to assess the efficacy of the HSV-TK suicide gene. Genetically modified tumor-infiltrating lymphocytes (TILs) were assayed for survival after withdrawal from exogenous IL-2. The activity and specificity of retrovirally transduced TILs were assessed using tumor coculture assays. RESULTS: Human T cells transduced with the IL-15 HSV-TK vector exhibited thymidine uptake in the absence of exogenous cytokine support and survived in culture for up to 80 d without IL-2. IL-15 HSV-TK-transduced T cells were efficiently killed by ganciclovir at concentrations as low as 0.1 µM. TILs transduced with the IL-15 HSV-TK vector retained specific recognition of HLA-A2+, MART1+ melanomas, even after withdrawal of IL-2. CONCLUSIONS: Human T lymphocytes genetically modified with the IL-15 HSV-TK retroviral vector retained the ability to recognize tumor antigen while gaining the ability to secrete IL-15 and prolong their own survival. IL-15 HSV-TK-transduced T cells expressed HSV-TK and could be efficiently eliminated by ganciclovir.

T-cell receptor gene therapy of established tumors in a murine melanoma model.

Adoptive cell transfer therapy using tumor-infiltrating lymphocytes for patients with metastatic melanoma has demonstrated significant objective response rates. One major limitation of these current therapies is the frequent inability to isolate tumor-reactive lymphocytes for treatment. Genetic engineering of peripheral blood lymphocytes with retroviral vectors encoding tumor antigen-specific T-cell receptors (TCRs) bypasses this restriction. To evaluate the efficacy of TCR gene therapy, a murine treatment model was developed. A retroviral vector was constructed encoding the pmel-1 TCR genes targeting the B16 melanoma antigen, gp100. Transduction of C57BL/6 lymphocytes resulted in efficient pmel-1 TCR expression. Lymphocytes transduced with this retrovirus specifically recognized gp100-pulsed target cells as measured by interferon-gamma secretion assays. Upon transfer into B16 tumor-bearing mice, the genetically engineered lymphocytes significantly slowed tumor development. The effectiveness of tumor treatment was directly correlated with the number of TCR-engineered T cells administered. These results demonstrated that TCR gene therapy targeting a native tumor antigen significantly delayed the growth of established tumors. When C57BL/6 lymphocytes were added to antigen-reactive pmel-1 T cells, a reduction in the ability of pmel-1 T cell to treat B16 melanomas was seen, suggesting that untransduced cells may be deleterious to TCR gene therapy. This model may be a powerful tool for evaluating future TCR gene transfer-based strategies.