Implementation and execution of nationwide molecular tumor boards (MTBs) in resource-limited settings: The “Molecular Thursdays” initiative.

e13895 Background: The increased access to broad next-generation sequencing (NGS) panels in routine oncology care has created a demand for education in molecular data interpretation and actionability ranking for clinical decision-making. Our lab has initiated the first open virtual MTB in Brazil, where access to broad NGS is largely restricted to pharma-sponsored patient support programs in certain tumor types, such as lung adenocarcinoma. The "Molecular Thursdays" bring together pathologists, geneticists, molecular biologists, and oncologists to discuss complex cancer cases from our healthcare network. Our objective is to describe the three-year experience building the program in a resource-limited setting for access to testing and targeted therapies. Methods: We retrospectively analyzed all cases presented at our MTB from 2022 to 2024 to describe overall organization, participation metrics, tumor types and indications, technologies and outcomes. Results: Over three years, 54 virtual sessions were conducted, with 3,161 total connections and an average of 60 participants per session. We found a slight reduction of participation over time, with average 64 connections per session in the first two years and 46 in 2024. Most participants were oncologists from the network (57%), but external physicians (27%) and other healthcare professionals (16%) also participated. Of 157 cases reviewed (3 per session), 78% involved metastatic cancers, 75% had in-house tissue broad NGS panels, 9% had liquid biopsy panels and 12% germline sequencing results. In more than 90% of the cases, the decision to discuss the genomic findings in the MTB came directly from the laboratory, while a direct request from the treating physician was exceptional (less than 5% of the cases). Discussions around therapeutic actionability of genomic findings occurred in 83% of the cases, and the remaining involved molecular pathology diagnostic dilemmas. The most common tumor types were lung adenocarcinomas (36%) and gastrointestinal cancers (23%), followed by rare tumors (primarily sarcomas, 13%), and breast cancer (7%). Regarding molecular alterations, variant pathogenicity of mutations was commonly discussed (64%), followed by actionability of gene fusions (24%), genomic signatures (9%), and gene amplifications (3%). Conclusions: The “Molecular Thursdays” are shaping the national precision oncology ecosystem. Establishing MTBs in resource-limited settings is challenging, requiring multidisciplinary collaboration to foster peer-to-peer discussions on genomic testing results. Our MTB serves as an educational platform, refining NGS utilization, facilitating optimal clinical decision-making and promoting community-wide knowledge sharing. Session recordings are available at: https://grupooncoclinicas.com/categoria-educacao-medica/videos .