Therapeutic efficacy of combined administration of thymosin and oxaliplatin in elderly gastric ulcer patients and its effect on cellular immunity and matrix metalloproteinase

Purpose: To investigate the clinical efficacy of thymosin combined with oxaliplatin and tiggio in aged gastric cancer (GC) sufferers, as well as their impact on cellular immunity and matrix metalloproteinase. Methods: Elderly GC sufferers (n = 82) were divided into study and control groups by random allocation (41 patients/group). Control group was treated with oxaliplatin combined with tiggio, while the study group was treated with thymopeptide injection, in addition to oxaliplatin combined with tiggio. Each treatment course lasted 21 days, and the study involved three courses. Clinical effectiveness and toxicity in the two groups were determined and compared before and after treatment. Results: Total effectiveness in the study group (73.16 %) and disease remission (95.11 %) were superior to the corresponding values for control patients given oxaliplatin and tiggio (48.78 and 85.37 %, respectively, p ˂ 0.05). There were markedly lower incidences of nausea, vomiting and leukopenia in the study group than in control (p ˂ 0.05). Conclusion: The use of thymosin-oxaliplatin-tigeo triple therapy for aged GC sufferers has a definite clinical benefits and low toxic side effects.


INTRODUCTION
Gastric cancer, one of the malignant tumors of the digestive system kills about 700,000 people every year.Mortality from GC accounts for onethird of mortalities from all malignant tumors, and most of the affected are the elderly population (70 -80 years old) [1].There are no typical symptoms in the early stage of GC.Therefore, most patients are diagnosed at the middle and late stages of the disease, and so lose the best opportunity for surgical treatment.Thus, chemotherapy has become the key to comprehensive treatment of GC.Owning to deterioration of body function in the elderly and other factors, they are unable to cope with the toxic and side effects of chemotherapy, leading to further reduction in immune function and poor curative effects.Choosing the best chemotherapeutic regimen for reducing the incidents of toxicity and side effects has become the focus of clinical treatment for elderly patients with gastric cancer.Studies have shown that platinum-containing chemotherapy can significantly improve the clinical symptoms and prolong the survival time of patients with gastric cancer.
Tiggio is a new type of fluorouracil-based chemotherapy which has achieved good results in the treatment of GC [2].Thymosin, an immune potentiator, enhances the maturation and differentiation of T lymphocytes and also reduces the side effects of chemotherapy [3].Therefore, in this study, the impact of combination treatment with thymosin, oxaliplatin and tiggio on aged GC sufferers was investigated with respect to cellular immunity, matrix metalloproteinase and endocrine function of tumors.

EXPERIMENTAL Patients' clinical profiles
Elderly GC sufferers (n = 82) on admission at the Oncology Department of our hospital from August 2016 to August 2017 were selected.The criteria for inclusion were as follows: (1) those who satisfied the conditions for diagnosis of gastric cancer [4], and were confirmed by pathological, cytological and imaging examinations; (2) patients in TNM stages III to IV; (3) patients aged over 60 years, and with expected survival time over 3 months; (4) patients with at least one lesion measured according to RECIST [5]; (5)

Treatments
The patients in the control group were treated with oxaliplatin combined with tiggiol regimen.On the first day, oxaliplatin (130 mg/m 2 ) was slowly and intravenously dripped for 2 h once a day.From the first to the 14th day, tiggio capsules were orally taken after meals twice a day.The study group was treated with thymosin, in addition to the chemotherapy regimen in the control group.The treatment involved 80 mL of thymosin in 500 mL of 5 % glucose given intravenously, once a day.One treatment course was 21, and there were three courses of treatment.The two groups were not given any other anticancer drugs.During the treatment period, they were closely observed.In order to give symptomatic treatment for toxic and side effects, the heart, liver and kidney functions were determined regularly.

Therapeutic indices
Fasting venous blood was collected before and after treatment for both groups.Serum samples were obtained by centrifugation and kept in refrigerator below 20 ℃.

Efficacy
Curative effect was evaluated in line with the evaluation standard of solid tumor treatment effectiveness standard (RECIST), with the following criteria: (a) Complete remission (CR): complete disappearance of lesion sustained for at least 4 weeks; (b) Partial remission (PR): 50 % decrease in the sum of the maximum vertical diameter product, for a minimum period of 28 days; (c) Stability (SD): < 50 % decrease in the sum of the maximum vertical transverse diameter product of the tumor lesion, or less than 25 % increase in same, lasting for at least 4 weeks.Progression (PD): at least one lesion increased by > 25 %.Total effectiveness (ORR) and CBR were calculated as in Equations 1 and 2. ORR = {(CR + PR)/D}100 ………… (1) CBR = {(CR + PR + SD)/T}100 …… (2) where D and T are total number of disease remissions, and total effectiveness, respectively.

Statistical analysis
Measurement data are expressed as mean ± standard deviation (x ± s).Groups were compared using Student's t-test.Numeric data are expressed as numbers (percentage) i.e., n (%), and were analyzed using Chi square (χ²) test via SPSS16.0(IBM, USA).Values of p ˂ 0.05 were considered statistically significant.

Clinical efficacy of the treatments
As shown in Table 2, after treatment, the total effectiveness and disease remission in the study group were 73.16 and 95.11 %, respectively, and were superior to the corresponding values in control patients (48.78 and 85.37 %, respectively, p ˂ 0.05).

Cellular immune status
As shown in Table 3, before treatment, CD3+, CD4+, CD8+ and CD4+/CD8+ levels were comparable amongst patients in both groups (p ˃ 0.05).However, after treatment, these parameters were markedly increased, relative to pre-treatment levels, except CD8+ which was less than the corresponding pre-treatment level (p ˂ 0.05).There was markedly greater improvement in the thymosin-treated patients than in control patients (p ˂ 0.05).

Matrix metalloproteinase levels in the patients
Before treatment, MMP-2 and MMP-9 levels were comparable between both categories of patients (p ˃ 0.05).However, post-treatment MMP-2 and MMP-9 values were markedly reduced in both groups, but were significantly lower in the study group than in the control group (p ˂ 0.05).These results are displayed in Table 4.

Tumor endocrine indices
Before treatment, VEGFA, VEGFC and sVEGFR-1 levels were comparable in patients in both groups (p ˃ 0.05).After treatment, VEGFA and VEGFC in the study group were decreased markedly, relative to levels in control, while was significantly increased (p ˂ 0.05; Table 5).

Adverse reactions
As shown in Table 6, during the treatment period, there were no serious side effects such as liver, kidney dysfunction, diarrhea and peripheral nerve inflammation in the two groups.However, post-treatment incidents of nausea, vomiting, leukopenia and neutropenia in patients in the study group were markedly lesser in the thymosin-treated patients than in control patients (p ˂ 0.05).

DISCUSSION
Studies have shown that the occurrence of gastric cancer is closely related to diet, smoking, Helicobacter pylori infection and host genetic susceptibility [7,8].Effective inhibition of tumor development and prolongation of patient survival have become the focus of current research on gastric cancer.
Currently, the popular chemotherapeutic drugs include platinum, fluorouracil and purple shirts.Oxaliplatin is a broad-spectrum anticancer drug which rapidly binds to DNA in vivo and has high anti-tumor activity [9].Being a third-generation fluorouracil derivative composed of oltipraz, gemcitabine and tegafur, teggio has high bioavailability and long duration of action, and can be combined with oxaliplatin.This effectively improves the therapeutic effect against gastric cancer, but the combination of the two drugs affects the normal cells of the body while killing the tumor cells, a situation which further compromises the immunity of patients and reduces their quality of life [10].
Thymosin, an immune enhancer, regulates and enhances cellular immunity.In this study, the combination of thymosin and chemotherapy drugs for gastric cancer treatment achieved excellent curative effects.After treatment, the total effectiveness and disease remission in the study group were 73.16 and 95.11 %, respectively, and were significantly higher than corresponding values in the control group (78.78 and 85.37 %, respectively).In addition, incidents of nausea, vomiting, leukopenia and neutropenia in the study group were markedly reduced in the study group.
These results indicate that combination therapy with thymosin and oxaliplatin for gastric cancer patients can effectively reduce the infiltration of tumor cells and prevent the development of the disease [11].Post-treatment CD3+, CD4+ and CD8+ were markedly increased in the thymosin-treated patients, and their CD8+ levels were markedly decreased, relative to control patients.These findings confirm that the use of thymosin combined with oxaliplatin tiggiol significantly improves the cellular immunity of patients, and is significantly better than the use of oxaliplatin combined with tiggiol.These results suggest that thymosin acted like a multifunctional cytokine, inducing T lymphocyte differentiation and maturation, and enhancing the levels of various lymphokines and their receptors.Since T lymphocyte subsets play leading roles in immune function, the levels of T lymphocytes are optimized after thymosin treatment, thereby maintaining balance in immune response, and improving immunity [12,13].
Matrix metalloproteinases MMP-2 and MMP-9 are two important factors which can be effectively used to evaluate the degree of malignancy and tumors invasion.Related studies have shown that matrix metalloproteinases degrade and remodel extracellular matrices, thereby maintaining a balance in the basement membrane, and regulating tumor invasion and metastasis [14].The results of this study showed that the combination of thymosin with oxaliplatin in the study group significantly reduced the levels of MMP-2 and MMP-9, indicating that the combination is capable of enhancing immunity and reducing the invasive ability of the tumor, thereby improving patient survival.This may be attributed to the fact that tiggio up-regulates the expression of caspase-3 by inhibiting the expression of survivin, accelerating apoptosis of tumor cells, thereby achieving anti-tumor effects [15,16].
Tumor cells release large amounts of cytokines involved in tumor invasion and metastasis.Vascular endothelium is acted upon by VEGFA and VEGFC to induce endothelial cell proliferation, while VEGFR-1 antagonizes VEGFA and VEGFC, thereby reducing the invasive ability of tumor cells.Post-treatment levels of VEGFA and VEGFC in the thymosintreated patients were markedly decreased, while sVEGFR-1 was elevated.Thus, the combination chemotherapy can effectively reduce cell infiltration in gastric cancer patients and prevent the development of tumor cells.

CONCLUSION
Thymosin combined with oxaliplatin effectively enhances therapy in aged GC sufferers, and produces low toxic and side effects.The combination treatment also elevates immunity, reduces tumor invasion and metastasis, and improves tumor endocrine function.Thus, the combination treatment plan may be considered for application in clinical practice.

Table 3 :
Cellular immune levels of patients (mean ± SD)

Table 4 :
Matrix metalloproteinase levels before and after treatment between the two groups (x ± s)

Table 6 :
Toxic and side effects {n (%)} . Chen A, Li CN, Hsu PI, Lai KH, Lai KH, Tseng HH, Hsu PN, Lo GH, Lo CC, Lin CK, Hwang IR, et al.Risks of interleukin-1 genetic polymorphisms and Helicobacter pylori infection in the development of gastric cancer.Fu W, Lu X, Zhang L. Clinical efficacy and safety of tiglio combined with oxaliplatinin the treatment of advanced gastric cancer with liver metastases.Mod Oncol Med 2018; (4): 553-556.14.Wang HZ, Li Xia, Shan XF, Li YH, Wang JS.Effects of oxaliplatin combined with tigeol on the expression of related proteins in advanced gastric cancer tissues.