Figure 2.

Total and phospho-Rb staining in skin biopsies. (A) Skin biopsies were obtained pre-treatment (pre) and 2 h after the first dose on day 22 of continuous ADZ5438 dosing. Five-micrometer sections from formalin-fixed, paraffin-embedded samples were subjected to immunohistochemistry with the indicated antibodies. Results from patient 23 are shown (treated at the 40-mg dose level), demonstrating reduced Rb staining at the S249/T252 and S780 phospho-sites in the keratinocyte layers, suggestive of reduced cyclin-dependent kinase activity after treatment. Total Rb staining is maintained in the post-treatment sample. (B) Immunohistochemical data were quantified by scoring the nuclei of 100–200 keratinocytes as 0, 1+ or 2+. The percentage of positive nuclei was considered as 100 for each pre-treatment sample. Bars indicate the percent positive staining (1+, 2+) in each post-treatment sample, relative to the pre-treatment sample. The x-axis designations indicate the patient number and the dose of AZD5438 administered. In these samples, reductions in phospho-Rb staining were noted, while total Rb staining was maintained after treatment.