Rechallenge with Anti-EGFR Therapy

Conference Correspondent - ASCO 2014 - Colorectal and Head & Neck Cancer

On the first day of in-depth presentations on mCRC, the focus was on finding novel first- and second-line therapies to treat patients, as well as identifying incremental improvements in existing therapeutic approaches that could result in better clinical outcomes and more rapid evaluation of the safety and efficacy of current and emerging agents. A retrospective study of 104 patients with KRAS?wild-type mCRC who had progressed on cetuximab or panitumumab therapy investigated whether retreating the patients with an EGFR-tyrosine kinase inhibitor (TKI) would be effective (Liu X, et al. ASCO 2014. Abstract 3607). Retreatment was with cetuximab alone or cetuximab plus erlotinib. The median interval length between initial treatment and retreatment was 4.55 months, with a range of 0.46 months (short interval) to 58.7 months (long interval). Patients who had responded to initial anti?EGFR-TKI therapy were more likely to respond to retreatment than those who had not initially responded (74% vs 45%; P = .013), and patients who had or had not responded to initial EGFR-TKI therapy were more likely to respond to retreatment at a longer interval between treatment cycles (46% responded to retreatment at a short interval and 66% responded to retreatment at a long interval; P = .001). These data suggest that the clonal evolution rationale for not using the same EGFR-TKI in patients who progress on initial EGFR-TKI therapy may not hold true in all cases and that retreatment with the same agent may be effective in some patients. A commentary on these data included the notion that “maintaining survival and decreasing costs by 35% or more in mCRC is possible by using only proven therapies that have been tested in appropriate clinical studies rather than on the basis of theoretical considerations.”