PROJECT SUMMARY/ABSTRACT Daily and intermittent/2-1-1 pre-exposure prophylaxis (PrEP) options are promising to end the HIV epidemic among transgender (trans) women — including in the Philippines where the HIV case infections recently doubled (1560 cases in 2022 vs. 714 in 2019) within a short timeline in this population.1,107 Understanding end-user input and preferences of PrEP via behavioral economic approaches like conjoint study designs are vital to maximizing its effectiveness such as feasibility, acceptability, and sustainability across its care continuum. However, to our team’s knowledge, no conjoint design studies have been applied to examine trans women’s end-user preferences for PrEP, including the co-use of gender-affirming hormones. Moreover, the socio-ecological barriers/facilitators pertinent to influencing PrEP uptake across the personal, social, economic, and structural levels are underexamined among trans women. As such, along with this study’s Trans Stakeholder and Scientist Advisory Board, this proposal aims to inform and test a future behavioral economic-based intervention to support PrEP engagement among trans women, with the following aims: (1) To qualitatively explore and identify all preferred and accepted attributes and features of PrEP needed to inform a full-profile PrEP program choice- based conjoint survey study via in-depth interviews with 30 trans women and 15 key informants (i.e., HIV specialists, primary care providers, PrEP programmers/policymakers), and (2) To quantitatively test and determine optimal combinations of attributes predictive of Filipinx trans women’s acceptability and preferences about PrEP modalities via full-profile choice-based conjoint study design with 300 Filipinx trans women to enhance implementation outcomes (e.g., acceptability, feasibility) of future intervention, and examine socio- ecological factors that may influence the chosen optimized PrEP program preferences. Findings will provide pilot data insights to test the identified optimized PrEP program profile(s) via a future larger scale (R01) behavioral economic-structural strengthening intervention for Filipinx trans women to increase PrEP uptake and reduce HIV incidence in the Philippines.