The Bridge Clinic: Optimizing Injectable PrEP Delivery for Transgender and Non-Binary People - Project Summary/Abstract Transgender and nonbinary (TNB) people are disproportionately affected by HIV, with increasing numbers of new diagnoses from 2015-2019. Pre-exposure prophylaxis (PrEP) has great potential to reduce new HIV infections, but has yet to improve HIV disparities among TNB populations. With the recent FDA approval of long-acting injectable cabotegravir (CAB-LA) for PrEP, there is a critical opportunity to leverage this scientific advance to increase PrEP use in TNB populations. In prior work, we piloted a flexible, low- threshold, trans-affirming PrEP clinic (Bridge Clinic) which achieved higher PrEP uptake and reached TNB individuals at higher risk for HIV acquisition than those receiving PrEP in gender affirming primary care clinics. Key components of the Bridge Clinic model include a nurse-led PrEP clinic with flexible hours; PrEP support provided by a trans peer navigator; text-messaging support via PrEPmate, a CDC-endorsed evidence based intervention; transportation support; and a TNB community-led PrEP awareness campaign. In this proposal, we will use Rapid-Cycle Research (RCR) methods to enhance the Bridge Clinic to incorporate CAB-LA delivery, refine this model through iterative adaptations, and assess key implementation outcomes. We will also evaluate for any drug interactions between gender affirming hormones and CAB-LA, an important question to address for the TNB community. In aim 1, we will conduct a series of nominal groups with English- and Spanish-speaking TNB people and semi-structured interviews with their providers to explore patient- and provider-identified barriers and facilitators to CAB-LA delivery in the TNB community. We will also elicit feedback on our implementation strategies to guide the enhancement of our protocol and engagement approaches to incorporate CAB-LA. In aim 2, we will implement the CAB-LA Enhanced Bridge Clinic model in an open cohort of 200 TNB individuals over a 3-year period, with mid-course adaptations guided by the RCR process. Using the RE-AIM framework, we will assess the reach, effectiveness, adoption, implementation, and maintenance of the Enhanced Bridge Clinic model via surveys and interviews with providers, staff, and patients, and medical record data review. In aim 3, we will enroll a subset of participants receiving injectable PrEP at the Bridge Clinic into two pharmacokinetic substudies to evaluate the bidirectional effects of gender affirming hormone therapy and cabotegravir plasma concentrations in TNB individuals. Our work across aims will be guided by a Stakeholder Advisory Board comprised of local and national community activists, leaders, health professionals, and staff serving the TNB community who will meet quarterly to provide input on study design and implementation, prioritization of adaptations, and ensuring the Bridge Clinic model is generalizable to other practice settings. Upon study completion, we will have optimized and evaluated a novel PrEP delivery model to increase uptake and persistence to long-acting injectable PrEP in TNB people, and assessed for drug interactions between gender affirming hormones and CAB-LA in a real-world cohort of TNB individuals.