I was part of clinical research where I was working on the quality control of medical images from the beginning of the trial to the end of the study. Most of the trials are carefully planned and executed as there are many lives involved and billions of dollars spent in conducting the trial. However there are a few cases where the trial is abruptly terminated from any further doses delivered to the patients. There might be two reasons for this: a. more than an expected minimum number patients are showing adverse reactions to the drug or b. the patients do not show any response to the drug at all (which means the disease is progressing). This might due a lot of factors. Success in animal studies gives only a minimal insight for a ‘possibly’ similar reaction in humans but does not necessarily mean they work all times. The factors that contribute to failed clinical trials maybe: 1. selecting patients who exhibit variedly different stages of the disease. It is easier to assess the progress of a disease when all the patients selected for the trial show similar activity and therefore possibly similar response to the drug. 2. genetic characteristics of the population of a particular gene pool. Patients belonging to different geographical locations react differently to the same drug. This can be due to the inherent differences in their DNA and also how the environmental factors play a huge rule in shaping the immune system.