A major issue identifying mechanisms of drug resistance is to explore different compounds on a monodrug basis. Clinically, the major reason for combining or administering sequentially an anthracycline and a taxane is the efficacy of each compound combined with a significant lack of cross-resistance. Administered as a combined schedule, this limits the possibility of identifying the mechanisms of resistance / sensitivity to each compound individually. Provided that a sequential regimen provides the same efficacy as a combined schedule, such an approach is justified ethically. Thus, for a patient given 2 and 3 drugs in concert, the potential may be they respond to one drug only, while having the toxicity of the other compounds. In case of non-responsiveness to a single compound, this may be exchanged for an alternative treatment option. This contrasts the possibilities provided in the adjuvant setting. In adjuvant therapy, there is no way by which we may assess the response to individual drugs; thus the different compounds have to administer in concert.