Within the past several years, no chemotherapy has been sufficient to increase 
the overall survival of patients with chemorefractory colorectal cancer. TAS-102 
(Lonsurf) is an oral fluoropyrimidine that is formed by the combination of 2 
active drugs: trifluridine (a nucleoside analog) and tipiracil hydrochloride (a 
thymidine phosphorylase inhibitor). This drug extended the median overall 
survival by approximately 2 months compared with placebo in a randomized phase 
III trial composed of Asian and non-Asian patients with refractory (or 
intolerant) metastatic colorectal cancer. The clinical development of TAS-102 
began approximately a decade ago and included 2 pivotal randomized studies, 
which are discussed in this review. This drug has just been approved in Japan, 
and as soon as possible, it will be marketed in Western countries as well; it 
will therefore become the standard of care for this patient population. The 
optimal combination of TAS-102 with other agents, as well as the mechanism of 
resistance to this regimen should be defined in the near future.