P1–341: Withdrawn

ratiowas 4:1, consistent with the ratio in the general population; that for avagacestat was 1:1.75. NMSC incidence rates among avagacestat-treated patients were higher than those from the claims database. Conclusions: This is the first clinical report characterizing NMSC in patients treated with a GSI. The NMSCs observed were readily identified and easily managed without recurrence. Increased NMSC incidence (especially SCC) and inversion of BCC:SCC ratio suggest that Notch inhibition oncogenically effects SCC. Further evaluation is warranted to understand potential oncogenic or suppressor effects of similar agents on skin cancer subtypes. The algorithms utilized in this study may help accurately identify and manage skin malignancies in studies using agents that affect epidermal differentiation.