139 Background: Clinical pathways have emerged as a tool for payers to encourage provider adherence to evidence-based care. Avalere sought to understand how oncology pathway developers consider different types of evidence and physician input in designing pathways, and how the experiences of early programs may serve as an indicator for future implementation. Methods: Avalere conducted targeted white and grey literature searches to identify and analyze pathways used by oncology practice groups, provider networks, and major commercial payers. The research was augmented by informant interviews with representatives from leading organizations that have developed or implemented pathways. Results: Current pathways programs differ in their origins and objectives. Across these programs, Avalere identified findings in three key areas: Development: Developers consider efficacy of treatments first, followed by toxicity, and then cost. Many developers conduct an independent evidence review, while others leverage clinical practice guidelines. All developers solicit physician input on pathway design and updates; Use: Independent pathway developers partner with commercial insurers and large provider networks to design pathways with cost-saving components. Physicians are evaluated based on their adherence to the pathways, but are not held accountable for reporting or performance on NQF-endorsed quality measures; Impact: Cost savings in early programs are largely due to reduced toxicity-related medical costs, use of less expensive drugs, and lower total drug use. However, there is limited evidence on the impact of pathways on patient outcomes. Conclusions: There is variability across oncology pathway developers regarding their scope, granularity, and processes related to evaluating and incorporating evidence. If clinical programs demonstrate early cost reductions while improving patient outcomes, payers will likely attempt to expand pathways programs to new geographies and therapeutic areas. Existing practice patterns and previously implemented pathways programs will likely play heavily in determining which pathways are adopted in a given region, but national standardization is highly unlikely.