Although depression is frequent among patients with advanced cancer. The objective of this study was to evaluate the impact of cognitive therapy on depressive patient. The participant (n=1) enrolled in the study was asked to complete daily and weekly mood assessments. Intervention time-series analyses conducted on daily mood data showed statistically significant improvement of depression symptoms, more importantly anhedonia, and associated features (i.e., anxiety, fatigue). These improvements were also found to be clinically significant at post-treatment.