Evaluating complete response prediction rates in locally advanced rectal cancer with different radiomics segmentation approaches.

Purpose: Studies examining prediction of complete response (CR) in locally advanced rectum cancer (LARC) from pre/post chemoradiotherapy (CRT) magnetic resonance imaging (MRI) are performed mostly with segmentations of the tumor, whereas only in two studies segmentation included tumor and mesorectum. Additionally, pelvic extramesorectal region, which is included in the clinical target volume (CTV) of radiotherapy, may contain information. Therefore, we aimed to compare predictive rates of radiomics analysis with features extracted from segmentations of tumor, tumor+mesorectum, and CTV. Methods and materials: Ninety-three LARC patients who underwent CRT in our institution between 2012 and 2019 were retrospectively scanned. Patients were divided into CR and non-CR groups. Tumor, tumor+mesorectum and CTV were segmented on T2 preCRT MRI images. Extracted features were compared for best area under the curve (AUC) of CR prediction with 15 machine-learning models. Results: CR was observed in 25 patients (26.8%), of whom 13 had pathological, and 12 had clinical complete response. For tumor, tumor+mesorectum and CTV segmentations, the best AUC were 0.84, 0.81, 0.77 in the training set and 0.85, 0.83 and 0.72 in the test set, respectively; sensitivity and specificity for the test set were 76%, 90%, 76% and 71%, 67% and 62%, respectively. Conclusion: Although the highest AUC result is obtained from the tumor segmentation, the highest accuracy and sensitivity are detected with tumor+mesorectum segmentation and these findings align with previous studies, suggesting that the mesorectum contains valuable insights for CR. The lowest result is obtained with CTV segmentation. More studies with mesorectum and pelvic nodal regions included in segmentation are needed.

Weekly paclitaxel treatment in the first-line therapy of classic Kaposi sarcoma: A real-life study.

Kaposi sarcoma is an angioproliferative disease associated with human herpes virus 8 infection. Classic Kaposi sarcoma (CKS) usually develops in older age. Although CKS often does not require systemic therapy, systemic therapy can be administered in progressively symptomatic patients. In this real-life study, we purposed to determine effectiveness and safety of weekly paclitaxel therapy in the first-line treatment of CKS. In this cross-sectional retrospective study, we analyzed the clinical data of 44 patients with CKS who received first-line paclitaxel therapy between January 2000 and December 2020. Paclitaxel was administered by intravenous infusion 80 to 100 mg/weekly. The median age of the patients was 67 years (range, 39-86 years), and majority male (77.2%). All patients had cutaneous involvement in extremities. The median follow-up time from paclitaxel treatment was 39.1 (range, 3.7-173.5) months. The median progression free survival from start of therapy was 35.1 months (range, 2-144 months). Complete response, partial response and stable disease were observed in 7 (15.9%), 28 (63.7%) and 6 (13.6) patients, respectively. Objective control rate was 79.6%, and the median response time after the last dose of paclitaxel was 18.2 months. A total of 4 patients (9.1%) had grade 3 to 4 neutropenia, but it was not complicated by febrile neutropenia. Three patients (6.8%) experienced grade 3 to 4 peripheral neuropathy. No patient had grade 3 to 4 allergic reaction. There was no drug-related death. According to our results, paclitaxel is an effective therapy option with an acceptable safety profile for patients with advanced CKS.

Access to Radiation Therapy by Syrian Refugees Displaced to Turkey.

For over 10 years, the Syrian conflict has caused millions of people to leave their homeland, causing one of the biggest refugee crises in modern history. Considering its prevalence, cancer is an important care burden among Syrian refugees. Radiation therapy is one of the essential parts of cancer treatment, and radiation oncology departments must guarantee optimal cancer treatments even in such a challenging setting when patients are displaced forcefully from their homes. National and institutional measures are highlighted in this manuscript to provide suggestions for the delivery of care during refugee crises. There are two issues creating barriers to serving refugee populations: the loss of access to their original care records in Syria for those with a previous diagnosis of cancer referred for continuation of radiation therapy or reirradiation, and the effect of acute radiation therapy toxicity on treatment compliance.

Complete Response Evaluation of Locally Advanced Rectal Cancer to Neoadjuvant Chemoradiotherapy Using Textural Features Obtained from T2 Weighted Imaging and ADC Maps.

BACKGROUND: The prediction of pathological responses for locally advanced rectal cancer using magnetic resonance imaging (MRI) after neoadjuvant chemoradiotherapy (CRT) is a challenging task for radiologists, as residual tumor cells can be mistaken for fibrosis. Texture analysis of MR images has been proposed to understand the underlying pathology. OBJECTIVE: This study aimed to assess the responses of lesions to CRT in patients with locally advanced rectal cancer using the first-order textural features of MRI T2-weighted imaging (T2-WI) and apparent diffusion coefficient (ADC) maps. METHODS: Forty-four patients with locally advanced rectal cancer (median age: 57 years) who underwent MRI before and after CRT were enrolled in this retrospective study. The first-order textural parameters of tumors on T2-WI and ADC maps were extracted. The textural features of lesions in pathologic complete responders were compared to partial responders using Student's t- or Mann-Whitney U tests. A comparison of textural features before and after CRT for each group was performed using the Wilcoxon rank sum test. Receiver operating characteristic curves were calculated to detect the diagnostic performance of the ADC. RESULTS: Of the 44 patients evaluated, 22 (50%) were placed in a partial response group and 50% were placed in a complete response group. The ADC changes of the complete responders were statistically more significant than those of the partial responders (P = 0.002). Pathologic total response was predicted with an ADC cut-off of 1310 x 10-6 mm2/s, with a sensitivity of 72%, a specificity of 77%, and an accuracy of 78.1% after neoadjuvant CRT. The skewness of the T2-WI before and after neoadjuvant CRT showed a significant difference in the complete response group compared to the partial response group (P = 0.001 for complete responders vs. P = 0.482 for partial responders). Also, relative T2-WI signal intensity in the complete response group was statistically lower than that of the partial response group after neoadjuvant CRT (P = 0.006). CONCLUSION: As a result of the conversion of tumor cells to fibrosis, the skewness of the T2-WI before and after neoadjuvant CRT was statistically different in the complete response group compared to the partial response group, and the complete response group showed statistically lower relative T2-WI signal intensity than the partial response group after neoadjuvant CRT. Additionally, the ADC cut-off value of 1310 × 10-6 mm2/s could be used as a marker for a complete response along with absolute ADC value changes within this dataset.

Adjuvant Treatment of Gastric Cancer in the D2 Dissection Era: A Real-life Experience from a Multicenter Retrospective Cohort Study.

BACKGROUND: The role of radiotherapy in the adjuvant treatment of gastric cancer (GC) remains to be elucidated. This study aimed to assess the additional benefit of radiotherapy in the adjuvant treatment of GC. MATERIALS AND METHODS: In this retrospective cohort study, we included 230 gastric adenocarcinoma patients who underwent D2 dissection between January 2004 and December 2019. Patients without R0 resection, who underwent metastasectomy at surgery, and treated with the neoadjuvant treatment were excluded. The co-primary endpoints were overall survival (OS) and disease-free survival (DFS). The secondary endpoints were the locoregional and distant metastasis risk and adverse events (AEs) leading to treatment discontinuation. RESULTS: One hundred and sixty-six and 64 patients were included in the chemoradiotherapy (CRT) and chemotherapy (ChT) arms, respectively. The median OS was 135.8 months [interquartile range (IQR): 99.4-172.2] and 97 months (IQR: 59.7-134.3) in the CRT and the ChT arms, respectively. No statistical significance was observed between the arms in OS (p = 0.3). Locoregional or distant recurrence rates were similar in each group. AEs leading to treatment discontinuation were higher in the CRT arm than in the ChT arm (13.2 vs 9.3%), and the difference between the arms was not statistically significant (p = 0.4). CONCLUSION: In this real-life study, we established that there was no additional benefit of RT in GC patients who underwent D2 dissection. HOW TO CITE THIS ARTICLE: Yekedüz E, Dogan I, Birgi SD, et al. Adjuvant Treatment of Gastric Cancer in the D2 Dissection Era: A Real-life Experience from a Multicenter Retrospective Cohort Study. Euroasian J Hepato-Gastroenterol 2021;11(2):51-58.

Outcomes of thymoma after multimodal therapy and determinants of survival: A 16-year experience of a tertiary cancer center.

BACKGROUND: In this study, we aimed to evaluate the factors that contribute to survival outcomes in patients with thymoma treated with multimodal approaches. METHODS: A total of 203 patients (105 males, 98 females; median age: 49 years; range, 17 to 77 years) with Masaoka-Koga Stage II-IV thymoma between January 2002 and December 2018 were retrospectively analyzed. Data including diagnosis of myasthenia gravis, diagnosis of diabetes mellitus, disease stage, histological type of tumor, capsule invasion and surgical margin status, lymphadenectomy, adjuvant radiotherapy or chemotherapy, time from surgery to the first day of adjuvant treatment, length of hospital stay, and overall and disease-free survival rates were recorded. RESULTS: Of the patients, 91 had Stage II, 67 had Stage III, and 45 had Stage IV disease. A total of 123 patients (61%) had myasthenia gravis. Seventy-six patients received adjuvant radiotherapy and 48 patients received either neoadjuvant (n=35) or adjuvant (n=25) chemotherapy. Higher disease stage, presence of R1 resection, and treatment with chemotherapy were significant factors for decreased disease-free survival time. Older age, higher disease stage, longer postoperative hospital stay, chemotherapy, and disease recurrence were effective contributors to decreased overall survival time. Adjuvant radiotherapy had a statistically significant positive effect on overall survival only in patients with completely resected Stage IV disease (five-year overall survival: 94.7% vs. 79.1%, respectively; p=0.015). In the multivariate analysis, older age (hazard ratio: 4.26), higher disease stage (hazard ratio: 2.95), and longer hospitalization time (hazard ratio: 3.81) were significant prognostic factors for overall survival. Patients with local recurrence who underwent complete resection had a survival time comparable to non-recurrent patients (p=0.753). CONCLUSION: For patients with thymoma, higher disease stage, age ≥50 years, longer hospitalization, and need for chemotherapy are associated with worse survival rates. Adjuvant chemotherapy has a positive impact on Stage IV disease. Resection of recurrent lesions has a valuable impact on survival.

Does nutritional status affect treatment tolarability, response and survival in metastatic colorectal cancer patients? Results of a prospective multicenter study.

BACKGROUND: The efficacy and tolerability of modern cytotoxic chemotherapy regimens used in malnourished metastatic colorectal cancer (mCRC) patients is uncertain. The aim of this study was to investigate the effect of malnutrition on efficacy and tolerability of cytotoxic chemotherapy and overall survival in mCRC patients. METHODS: In this multicenter study, demographic, oncologic and nutritional data were collected prospectively from mCRC patients. Nutritional status of the patients were evaluated on the basis of NRI (Nutritional Risk Assessment), BMI (Body Mass Index) and WL (Weight Loss) before the first chemotherapy, after the first and second chemotherapy during 2 cycles of chemotherapy every 15 days. To determine the inter-treatment weight loss toxicity assessment was included to theese parameters after each chemotherapy. NRI calculation was performed as [1.51xserum albumin level (g/L)+41.7xcurrent weight/basic weight]. NRIs were examined in 3 categories as 'no malnutrition' (NRI >97.5), 'moderate malnutrition' (97.5 ≥NRI ≥83.5) or 'severe malnutrition' (NRI <83.5). Response to treatment and drug-induced toxicities were assessed based on Criteria in Solid Tumors (RECIST) 1.1 and National Cancer Institute CTCAE version 4.0 respectively. RESULTS: One-hundred and thirty-seven mCRC patients were prospectively included. Median age was 48 (range 18-83). Primary location was colon in 66% of patients and 84% of their primary source was left colon. Malnutrition was detected in 39% of the cases. Response rate to treatment was twenty four percent. While there was no significant relationship between chemotherapy response and moderate/severe malnutrition (p = 0.24), moderate/severe malnutrition was associated with multipl site of metastases, WHO PS (World Health Organization Performance Status) of 1, over the median value of CEA/CA 19-9 (carcinoembryonic antigen/carbohydate antigen 19-9) levels (p = 0.003, p = 0.03, p < 0.001, and p = 0.02; respectively). Hypoalbuminemia and moderate/severe malnutrition were associated with all types of toxicity (p < 0.001 and p < 0.001). Moderate/severe malnutrition was associated with thrombocytopenia, and diarrhea following chemotherapy predominately, (p = 0.02 and p = 0.04; respectively). In moderate/severe malnutrition group median overall survival was prominently shorter than those with no malnutrition [6.6 moths (95%CI, 5.6-7.6) vs 11.9 moths (95% CI, 11.1-12.7) respectively, p < 0.001]. CONCLUSIONS: Our study showed that moderate/severe malnutrition in mCRC patients was associated with decreased overall survival and increased chemotherapy toxicity.

Investigation of approaches for internal target volume definition using 4-dimensional computed tomography in stereotactic body radiotherapy of lung cancer.

The present study was undertaken to investigate the suitability of alternative internal target volume (ITV) delineation strategies based on maximum intensity projection (MIP), average intensity projection (AIP), 2 extreme phases and 4 phases images relative to the ITV10phase in stereotactic body radiation therapy (SBRT) for lung cancer. The 4-dimensional computed tomography (4DCT) data of 15 lung cancer patients treated with SBRT in our clinic were used. Five different ITVs were generated as follows: merging GTVs from 10 phases (ITV10Phase); merging GTVs from 2 extreme phases (0%, 50%) (ITV2Phase); merging GTVs from 4 phases (0%, 20%, 50%, and 70%) (ITV4Phase); delineating GTV on MIP (ITVMIP), and delineating GTV on AIP (ITVAIP). PTV10Phase, PTV2Phase, PTV4Phase, PTVMIP, and PTVAIP were generated by adding a 5-mm margin around the related ITV. Volumetric analyses were performed for 4 ITVs and PTVs relative to ITV10phase and PTV10phase. SBRT plans made for all PTVs were evaluated for dosimetric effect of alternative ITV delineation strategies. The mean percentage overlap volume (POV) for PTV2phase, PTV4phase, PTVMIP, and PTVAIP relative to PTV10phase were 84.2 ± 5.4%, 92.0 ± 2.9%, 82.2 ± 5.7%, and 73.8 ± 9.3%, for lower-lobe tumors, respectively. The mean POV for PTV2phase, PTV4phase, PTVMIP, and PTVAIP relative to PTV10phase were 93.2 ± 2.5%, 95.9 ± 1.0%, 87.5 ± 6.7%, and 83.3 ± 6.8% for upper-lobe, respectively. For lower-lobe tumors the mean differences in V20 and MLD for plans based on PTV2phase and PTV4phase were <0.5% and <10 cGy, compared with a plan based on PTV10phase. The use of PTV based on 4 respiratory phases and a 5-mm margin is a safe approach to reduce the workload of target delineation for tumors located in both lower and upper lobes.

Prognostic factors in medically inoperable early stage lung cancer patients treated with stereotactic ablative radiation therapy (SABR): Turkish Radiation Oncology Society Multicentric Study.

OBJECTIVE: We identified factors influencing outcomes in patients with medically inoperable early stage lung cancer (MIESLC) treated with stereotactic ablative radiation therapy (SABR) at 14 centers in Turkey. MATERIALS AND METHODS: We retrospectively analyzed 431 patients with stage I-II MIESLC treated with SABR from 2009 through 2017. Age; sex; performance score; imaging technique; tumor histology and size; disease stage radiation dose, fraction and biologically effective dose with an α/ß ratio of 10 (BED10 ); tumor location and treatment center were evaluated for associations with overall survival (OS), local control (LC) and toxicity. RESULTS: Median follow-up time was 27 months (range 1-115); median SABR dose was 54 Gy (range 30-70) given in a median three fractions (range 1-10); median BED10 was 151 Gy (range 48-180). Tumors were peripheral in 285 patients (66.1%), central in 69 (16%) and <1 cm from mediastinal structures in 77 (17.9%). Response was evaluated with PET/CT in most cases at a median 3 months after SABR. Response rates were: 48% complete, 36.7% partial, 7.9% stable and 7.4% progression. LC rates were 97.1% at 1 year, 92.6% at 2 years and 91.2% at 3 years; corresponding OS rates were 92.6%, 80.6% and 72.7%. On multivariate analysis, BED10 > 100 Gy (P = .011), adenocarcinoma (P = .025) and complete response on first evaluation (P = .007) predicted favorable LC. BED10 > 120 Gy (hazard ratio [HR] 1.9, 95% confidence interval [CI] 1.1-3.2, P = .019) and tumor size (<2 cm HR 1.9, 95% CI 1.3-3, P = .003) predicted favorable OS. No grade 4-5 acute side effects were observed; late effects were grade ≤3 pneumonitis (18 [4.2%]), chest wall pain (11 [2.5%]) and rib fracture (1 [0.2%]). CONCLUSION: SABR produced encouraging results, with satisfactory LC and OS and minimal toxicity. BED10 > 120 Gy was needed for better LC and OS for large, non-adenocarcinoma tumors.

Serum nectin-2 and nectin-4 are diagnostic in lung cancer: which is superior?

Nectins are immunoglobulin-like molecules that are involved in cell to cell adhesion by forming tight junctions and homophilic/heterophilic interactions. This study aimed to analyze serum nectin­2 and nectin­4 levels in lung cancer patients and to evaluate the prognostic, diagnostic and predictive strengths. Data from 74 lung cancer patients were retrospectively examined and enzyme-linked immunosorbent assays (ELISA) were used to measure serum nectin­2 and nectin­4 concentrations. A total number of 40 age and sex-adjusted healthy controls were also enrolled in the study. The median serum nectin­2 and nectin­4 levels of the patients were significantly higher than those of controls (p < 0.001); however, neither biomarker was found to be associated with clinicopathological parameters, (p > 0.05), and furthermore they were found not to be correlated with either overall survival or progression-free survival (p > 0.05). Even though both markers showed high diagnostic values, serum nectin­2 was found superior to both serum nectin­4 and serum nectin-2 + nectin­4 combinations in the diagnosis of lung cancer according to higher sensitivity, specificity and predictive values. Serum nectin­2 and nectin­4 might be used in lung cancer diagnosis but the diagnostic importance of nectin­2 is higher. The prognostic and predictive strengths in cancer are controversial. Furthermore, the interactions with tumor microenvironments and the potentials as therapeutic targets for malignancies have yet to be elucidated.

Detection of serum protein and circulating mRNA of cMET, HGF EGF and EGFR levels in lung cancer patients to guide individualized therapy.

BACKGROUND: Reseptor tyrosine kinases (cMET and EGFR) are important in lung cancer targeted therapy. We believe if we can use them as markers for clinicians to help decide the diagnosis of lung cancer. This parameter will be important in serum samples of patients with lung cancer diagnosis and treatment. The aim of this study is aimed to evaluate the clinical utility of serum protein and circulating mRNA of cMET and HGF in lung cancer patients. We also analyzed the correlation of mRNA expression with clinicopathologic parameters. METHODS: We performed enzyme-linked immunosorbent assay (ELISA) to measure and compare serum protein and circulating mRNA of cMET and HGF levels in peripheral blood from 60 lung cancer patients and 40 healthy control group. RESULTS: We found that both protein and gene expression levels of serum c-MET, HGF and EGFR were significantly higher in patients with lung cancer than control group. There was no association between HGF, cMET, EGF, EGFR (both protein and gene) expression levels with age, gender, smoking habit, COPD, pathological types or tumor size, stage, metastatic-non metastatic adenocarcinoma-squamous carcinoma, SCLC-NSCLC. As a result of ROC analysis, serum cMET (AUC: 0.892) and HGF protein (AUC: 0.784) were diagnosed in lung cancer patients (Fig. 1). The AUC values of serum EGF and EGFR proteins were calculated to be 0.631 and 0.692, respectively. CONCLUSION: To our knowledge this is the first study comparing the levels of protein and mRNA in the serum material of HGF, c-MET, EGF and EGFR parameters in lung cancer patients' blood samples. Further prospective studies with more participants for better understanding of mechanism and effect for HGF and c-MET inhibitors in lung cancer will help us to identify of these biomarkers role for guiding us to sellect individualized itargeted therapies.

Abscopal Effect of Radiotherapy in the Immunotherapy Era: Systematic Review of Reported Cases.

Mounting evidence suggests that radiation stimulates the immune system and this contributes to the abscopal effect, which is defined as "response at a distance from the irradiated volume." Though identified more than 50 years ago, the abscopal effect is revisited today. One rationale is that the abscopal effect is often observed with efficient immunotherapy. Here, we give an overview of the clinical data on the abscopal effect, generated by a combination of immunotherapy and radiotherapy (RT). Only papers that included RT in combination with immunotherapy were evaluated according to four main categories including RT parameters, sequencing of therapies, the definition of the abscopal effect, and patient selection. Twenty-four cases in 15 reports were reviewed. The results varied. Patient ages ranged from 24 to 74. RT dose (median total dose 18-58 Gy) varied. Biologically effective dose (BED) 10 was calculated to be a median 49.65 Gy (28-151 Gy). The time to a documented abscopal response ranged from less than a month to 12 months. The large variation concerning fractionation and sequencing of therapies indicates that these conflicting points need to be resolved, to generate for the abscopal effect to be clinically significant.

Serum leptin levels may have diagnostic and predictive roles in patients with pancreatic adenocarcinoma treated with gemcitabine-based chemotherapy.

PURPOSE: Leptin is a highly pleiotropic adipokine. Pancreatic adenocarcinoma (PA) and leptin relationship is important. Our aim was to investigate the serum levels of leptin in patients with PA, the relationship of leptin with tumor progression and known prognostic parameters and its diagnostic, predictive and prognostic role. METHODS: Thirty-three patients with PA were investigated. Serum samples were obtained on first admission before treatment and follow-up. Both serum leptin levels were determined using enzyme-linked immunosorbent assay (ELISA). Age, sex, and body mass index (BMI) matched to 20 healthy controls were included in the analysis. RESULTS: The median patient age at diagnosis was 59 years (range 32-84) and 20 (61%) patients were men. The tumor was located in the head of pancreas in 21 (63%) patients. The most common metastatic site was liver in 23 patients with metastasis (N=19; 83%). The median follow-up time was 26.0 weeks (range 1.0-184.0). At the end of the observation period, 32 patients (97%) had died. The baseline serum leptin levels were significantly higher in patients with PA than in the control group (p=0.02). Thirty-nine percent of 23 metastatic patients who received palliative gemcitabine-based chemotherapy (gCTx) were gCTx-responsive. Serum leptin levels were significantly higher in the gCTx-unresponsive patients compared with gCTx -responsive (median 5.32 vs 1.16 ng/mL, p=0.004). Conversely, serum leptin concentration was found to have no prognostic role on survival (p=0.20). CONCLUSION: Serum leptin levels may be a good diagnostic and predictive tool on the response to gCTx in PA patients.

Definitive radiotherapy in locally advanced non-small cell lung cancer: dose and fractionation.

Definitive radiotherapy plays a major role in the treatment of locally advanced non-small cell lung cancer (LA NSCLC). After the impact of RT dose for lung cancer was established, a number of trials were structured with the aim of better local control and overall survival by either dose escalation or shortening the total treatment time through conventional/altered fractionation, even in combination with chemotherapy (CT) and other targeted agents. In spite of the increased number of these studies, the optimal dose or fractionation still remains to be determined. Another aspect questioned is the incorporation of these higher doses and shorter treatment times with chemotherapy or targeted agents. This review summarises the results of significant trials on dose and altered fractionation in the treatment of LA-NSCLC with an emphasis on possible future perspectives.

Thirteen week rodent feeding study with grain from molecular stacked trait lepidopteran and coleopteran protected (DP-ØØ4114-3) maize.

The results from a subchronic feeding study conducted in Sprague­Dawley rats fed with diets containing grain from 4114 (OECD unique identifier: DP-ØØ4114-3) maize that was untreated (4114) or sprayed in field with glufosinate ammonium (4114GLU) in a design similar to previous studies are reported. The test material, 4114 maize, is a hybrid maize produced by transformation with a DNA construct encoding 4 different transgenic proteins for resistance to lepidopteran pests, coleopteran pests, and tolerance to the herbicidal active ingredient glufosinate ammonium. There were a total of 144 rats divided into 12 groups of 12 rats/sex/group. All experimental diets were formulated by Purina Mills, LLC (St. Louis, MO) in accordance with the standards of Purina Mills Labdiet® Certified Rodent LabDiet® 5002. The incorporation rate of maize grain in all diets was 32% (wt/wt). No biologically significant, treatment related differences in body weight, food consumption, clinical pathology parameters (hematology, blood chemistry, urinalysis, or organ weight) were observed in rats consuming the diets containing 4114 maize grain compared with rats fed conventional maize diets. A number of histologic observations were noted in this study but were background lesions and representative of what would be expected for rats of this age and strain. An independent panel of experts determined certain observations to be spontaneous and not related to the test diet. Accordingly, these results support the conclusion that 4114 maize grain is as safe and nutritious as conventional maize grain.

Two-generation reproductive and developmental toxicity assessment of dietary N-acetyl-L-aspartic acid in rats.

N-acetyl-l-aspartic acid (NAA) is a component of the mammalian central nervous system (CNS) that has also been identified in a number of foods. This paper reports the outcome of a reproductive toxicology study conducted with NAA in Sprague-Dawley rats. NAA was added to diets at target doses of 100, 250 and 500 mg/kg of body weight/day and administered for two consecutive generations. A carrier control group was administered diet with no added NAA and a comparative control group was given aspartate (ASP), the constituent amino acid of NAA, at a target dose of 500 mg/kg of body weight/day. The study evaluated OECD 416 reproductive performance variables and additional segments to assess potential developmental effects, neurobehavioural and ophthalmologic function, and the concentrations of NAA or ASP in brain and plasma. No biologically significant differences were observed in any reproductive response variables, neurobehavioural tests, ophthalmologic examinations, body weights, feed consumption, or organ weights. Further, no test substance related mortalities or adverse clinical, neurohistopathologic or histopathologic findings were observed. Under the conditions of this study, the highest target dose of NAA, 500 mg/kg of body weight/day, represents the no-observed-adverse-effect-level (NOAEL) for reproductive and systemic toxicity, and neurotoxicity for Sprague-Dawley rats.

Subchronic oral toxicity assessment of N-acetyl-L-aspartic acid in rats.

We investigated the systemic effects of subchronic dietary exposure to NAA in Sprague Dawley® rats. NAA was added to the diet at different concentrations to deliver target doses of 100, 250 and 500 mg/kg of body weight/day and was administered for 90 consecutive days. All rats (10/sex/group) survived until scheduled sacrifice. No diet-related differences in body weights, feed consumption and efficiency, clinical signs, or ophthalmologic findings were observed. No biologically significant differences or adverse effects were observed in functional observation battery (FOB) and motor activity evaluations, hematology, coagulation, clinical chemistry, urinalysis, organ weights, or gross pathology evaluations that were attributable to dietary exposure to NAA. Treatment-related increased incidence and degree of acinar cell hypertrophy in salivary glands was observed in both male and female rats in the high dose group. Because there was no evidence of injury or cytotoxicity to the salivary glands, this finding was not considered to be an adverse effect. Based on these results and the actual average doses consumed, the no-observed-adverse-effect-levels (NOAEL) for systemic toxicity from subchronic dietary exposure to NAA were 451.6 and 490.8 mg/kg of body weight/day for male and female Sprague Dawley® rats, respectively.

Mutagenicity studies with N-acetyl-L-aspartic acid.

Analytical studies have reported that N-acetyl-L-aspartic acid (NAA) is present at low concentrations in many foods. The current studies were conducted to assess the mutagenicity of NAA using standard OECD guideline in vitro bacterial and in vivo mammalian mutagenicity studies. For comparison and control data, mutagenicity studies were also conducted with its constituent amino acid L-aspartate (ASP) because NAA is metabolized to ASP. The combination of an in vitro method for assessing point mutations in bacteria and an in vivo method to assess clastogenicity in an animal model provided adequate evidence for mutagenicity hazard assessment of NAA. No evidence of mutagenicity was observed in either test system with either NAA or ASP. The results from the current studies demonstrate that the presence of NAA in foods is not likely to represent a risk for mutagenicity.

Analysis of immune response in young and aged mice vaccinated with corn-derived antigen against Escherichia coli heat-labile enterotoxin.

Enterotoxigenic strains of Escherichia coli produce a heat-labile holotoxin (LT), which causes diarrhea. We engineered corn seeds to produce LT-B, the nontoxic subunit of LT, to serve as a plant-derived vaccine to traveler's diarrhea and as an adjuvant for co-administered proteins. We previously demonstrated that a strong mucosal and systemic antibody response is elicited in young mice with oral administration of corn-derived LT-B. The present study examined systemic and mucosal antibody responses to LT-B in young and aged mice, and recall responses to oral administration and injection of LT-B in aged mice. Specific IgA and IgG antibodies were detectable during an 11-mo period, although the concentration of antigen-specific antibodies declined gradually. Booster by feeding or injection dramatically increased the concentration of specific IgA from that seen in young mice. Specific IgG levels were boosted to concentrations similar to those in young mice. This effect may be age-dependent and related to prior immunization exposure. Analysis of the antibody response of naïve aged mice against corn-derived LT-B demonstrated an age-related suppression in specific IgG production, but not specific IgA. These results may provide important information for edible vaccine strategies for young and aged individuals.