Wacker B et al. (2007) Correlation between development of rash and efficacy in patients treated with the epidermal growth factor receptor tyrosine kinase inhibitor erlotinib in two large phase III studies. Clin Cancer Res 13: 3913–3921

Patients treated with EGFR inhibitors frequently develop a rash. Previous studies have suggested a positive association between outcome and rash development. A study by Wacker et al. has examined the correlation between the clinical efficacy of EGFR inhibitors and the development of rash using data from two phase III studies.

The BR.21 study included 444 erlotinib-treated and 229 control patients with non-small-cell lung cancer. Patients with grade 1 rash survived 144% longer than patients who did not develop rash (hazard ratio [HR] 0.41; P <0.001), while patients who developed a rash of grade ≥2 survived 245% longer than did patients with no rash (HR 0.29; P<0.001). Progression-free survival also correlated with the occurrence and severity of rash (HR 0.51, P < 0.001 for grade 1 rash; HR 0.35, P < 0.001 for grade 2 rash). In the erlotinib-treated group, disease control rate increased with the development and severity of rash (P <0.001 for both grade 1 and 2 rash versus grade 0). The PA.3 study included 254 patients with pancreatic cancer treated with erlotinib plus gemcitabine and 245 patients who received only gemcitabine (control group). In comparison with controls, only patients with grade ≥2 rash had improved overall survival (HR = 0.47; P <0.001), progression-free survival (HR = 0.43; P <0.001), and disease control (P = 0.002).

The authors conclude that development of rash should be considered an indicator of a positive clinical outcome in erlotinib-treated patients.