Methods for predicting response to arginine deprivation therapy based on plasma arginine levels in cancer patients

A method of in vitro identifying the arginine threshold in biological samples of cancer subjects to predict whether the subjects respond to arginine deprivation therapy, comprising:

• providing a biological sample, the biological sample taken from a subject prior to be administrated an arginine deprivation agent;
• determining an arginine concentration, measuring the arginine concentration in the biological sample;
• calculating an overall survival, the overall survival statistics are assessed after the subjects undergo the arginine deprivation therapy;
• calculating an arginine cut-off point, inputting the arginine concentration and the overall survival of the subjects into the statistical method of maximally selected log-rank statistics to determine the arginine cut-off point;
• and
• calculating an arginine threshold, based on the arginine cut-off point to be the highest arginine value and gradually decrease the value of arginine and calculate the corresponding p-value for each arginine value, continuing this process until the p-value for the nth arginine value is higher than 0.05, then the (n−1)th arginine value is the arginine threshold,
• wherein, when the arginine concentration of the subjects is greater than or equal to the arginine threshold, it means that the cancer subject responds well to the arginine deprivation therapy.