Evaluation Of The Neuroprotective Effect Of Cinobufacini Against Oxaliplatin-induced Neurotoxicity. A Study In Gastrointestinal Cancer Patients And Animal Model

Purpose:Oxaliplatin-based chemotherapy is widely used for the management of gastrointestinal cancers.One of the major dose-limiting adverse effects of oxaliplatin is neurotoxicity which may be troublesome for many patients and can even affect treatment efficacy.Till now,there are no effective drugs to treat oxaliplatin-induced peripheral neuropathy(oxaipn)and the exact mechanisms underlying its pathogenesis are not known.Cinobufacini also named as huachansu is a traditional Chinese medicine which can enhance chemotherapy effect and can reduce the side effects of chemotherapy.Huachansu has proved also to be a safe drug with no major dose limiting toxicities.Moreover,it contains cinobufagin which has been found to be effective in cancer pain based on pre-clinical studies and also our clinical observation.So we assumed that huachansu could possibly play a role in neuropathic pain relief.However,there are no past studies up to now which have assessed the specific influence of cinobufacini on oxaipn.To verify our speculation that huachansu could be useful in the management of oxaipn,we initiated this study to first evaluate the preventive effect of cinobufacini on oxaipn and secondly we investigated a possible mechanism of the action for the neuroprotective effect of huachansu in an animal model of oxaliplatin-induced peripheral neuropathy.Methods:Our study was divided into two parts:a clinical study and animal study using a rat model of oxaliplatin-induced peripheral neuropathy.1.clinical study:it was a prospective randomized controlled study performed on histopathologically proven gastric and colorectal cancer patients at the Liaoning Cancer Hospital.A number(n)of 15 patients were eligible for this clinical trial and there were 8 males and 7females,with median age of 61 years.The patients were randomly divided into an experimental group(n=6)and a control group(n=9).Peripherally inserted central venous catheters(PICC)were placed on every patients.The site of insertion of the PICC whether on the left or right side of the patient were as follows:(total left=7,total right=8);experimental group(left=3,right=3):control group(left=4,right=5).The patients were treated with XELOX chemotherapy regimen(i.e,.intravenous drip of oxaliplatin 130 mg/m~2 over 2 hours on day(D)1and capecitabine 1000 mg/m~2 twice orally from D1-D14)which was of 6 cycles duration where each cycle was repeated every 21 days.In the experimental group,intravenous cinobufacini mixed with 5%glucose injection 500 ml once a day from D1–7 and oxaliplatin-based chemotherapy were administered to the patients.In the control group,only XELOX chemotherapy was used.After 6 cycles of treatment,the bilateral sural nerve conduction velocities in meter/seconds(m/s)were measured and the results were expressed as mean(M)±standard deviation(SD).The differences in the degree of nerve injury between the two groups was quantitatively analysed using the independent t-test.2.Rat model of oxaliplatin-induced neuropathy:The experiment was performed with 42 male Sprague Dawley rats,weighing about 180-200g.The animals were randomly divided into three groups(14 rats in each group)and the drugs were administered intraperitoneally(i.p)as follows:oxaliplatin+cinobufacini group(oxaliplatin at 4 ml/kg on D1-2 for 4 cycles and cinobufacini at 5 ml/kg on D1-3,7 for 4 cycles);oxaliplatin group(oxaliplatin at 4 ml/kg on D1-2 for 4 cycles and 5%glucose solution at 5ml/kg on D1-3,7 for 4 cycles);control group(5%glucose solution only on D1-3,7 for 4 cycles at same doses as in the oxaliplatin+cinobufacini group).The experiment lasted 4 weeks.Neurotoxicity was assessed by measuring the level of reduced glutathione(GSH)in each of the samples of sciatic nerve dissected from the rats.The Solarbio GSH assay kit and spectrophotometry were used during the experiment.The results for GSH values in microgram/milliliter(?g/ml)were reported as M±SD.One-way Analysis of Variance(ANOVA)and the Fisher's Least Significant Difference(LSD)post-hoc analysis were performed as statistical tests.All data in our study were analysed using SPSS version 19.0 and Statistical significance was set at p<0.05.Results:1.Clinical study:The results for our findings in the clinical study were:right sural nerve after treatment(M±SD in experimental group=45.37±3.14 m/s,M±SD in control group=42.96±5.25 m/s,p=0.334)and left sural nerve after treatment(M±SD in experimental group=48.40±4.06 m/s,M±SD in control group=42.74±5.14 m/s,p=0.042)The nerve conduction velocity test firstly showed that mean nerve conduction velocity for the right sural nerve after 6 cycles of treatment in the experimental group was higher than that of the control group but the difference between the two groups was not statistically significant.(p>0.05)The mean nerve conduction velocity in the left sural nerve after 6 cycles of treatment was higher in the experimental group compared to the control group.There was a statistically significant difference between the two groups for the left sural nerve.(p<0.05)2.Rat model of oxaliplatin-induced neuropathy:.The mean GSH values in the dissected sciatic nerves of the rats for each group were as shown:oxaliplatin+cinobufacini group(n=14,M±SD=233.35±26.25?g/ml);oxaliplatin group(n=14,M±SD=185.21±24.53?g/ml);control group(n=14,M±SD=324.96±28.61?g/ml).The differences in mean GSH values among the three groups with the one way ANOVA test were statistically significant.(p=0.002).The results for group comparisons with Fisher's LSD post-hoc test were as follows oxaliplatin+cinobufacini v/s control(P=0.019);oxaliplatin+cinobufacini v/s oxaliplatin(p=0.207);oxaliplatin v/s control(P=0.001).The mean GSH value of oxaliplatin+cinobufacini group was higher than the oxaliplatin group but the difference was not statistically significant.(p>0.05).Conclusion:To our knowledge,there were no previous studies which have been carried out to assess the efficacy of cinobufacini in preventing neurotoxicity associated with oxaliplatin.1.Based on the results of our clinical study,it was demonstrated that injection of cinobufacini can relieve oxaliplatin-induced neurotoxicity.2.The results of the rat model of oxaliplatin-induced chemotherapy showed that the regulation and increase of GSH level in nerve cells may be one of the mechanisms for the neuroprotective effect of cinobufacini.However,further research are needed to substantiate our results.