Rechallenge Strategy in Cancer Therapy

Drug resistance is one of the most important factors limiting the success of systemic anticancer therapy in achieving cure or prolonged overall survival. In clinical practice, resistant disease describes cancer that is found to have progressed since the time of treatment initiation. The term “drug resistant” is often used synonymously with “progressive disease” when referring to a treated tumour. Stopping a treatment at the time of disease progression is the current dominant approach of clinical trial conduct; therefore, available data from clinical trials are routinely not able to provide any information that could challenge this concept of permanent drug resistance. However, drug rechallenge and treatment continuation beyond progression have emerged as potential strategies in the past decade, especially for molecularly targeted agents and immunotherapy. In this review we focussed on rechallenge strategies for chemotherapy, immune therapy and targeted therapy in the main types of cancer.