ASK-PrEP is a two-arm randomized controlled trial (RCT), with a Stepped Care approach, to determine the optimal (considering effectiveness and cost-effectiveness) intervention, or combined interventions for advancement along the PrEP Care Continuum, and reductions in substance use among HIV-negative trans women (TW) and men who have sex with me (MSM), with a substance use disorder (SUD; N=250). After screening, informed consent, and baseline assessment, participants will be randomized (3:1) into one of two arms: ASK-PrEP Stepped Care or Standard of Care (SOC) control. At 3-month follow-up assessments, responders will be maintained in ASK-PrEP for an additional 3 months; non-responders will be stepped up and re-randomized (1:1) to either ASK-PrEP+CM or CM alone. Thus, non-responders will receive added attention to their SUD via CM; i.e., non-responders will either: a) receive CM in addition to a continued focus on PrEP adherence and other behavioral health issues (ASK-PrEP+CM), or b) shift the primary attention to their SUD (CM alone). Participants may choose to initiate daily oral PrEP (Truvada or Descovy) or long-acting injectable Cabotegravir. The 3-month step criteria are based on: 1) PrEP initiation and adherence; 2) substance use; and 3) HIV sexual risk behaviors if the participant has not initiated PrEP. The study uses repeated assessments at baseline and at 3-, 6-, 9-, and 12-months post-enrollment, via an "intent-to-treat" design, where all assessments are administered to participants regardless of their engagement or retention. All intervention content is tailored to TW/MSM with a SUD.

ASK-PrEP is a PrEP navigation intervention with text-messaging support. The navigation component is based on mechanisms of the Reasoned Action Approach (RAA), and the text-messaging support component is based on Social Support Theory (SST). In Session 1, the PrEP navigator uses the Needs and Barriers Assessment (NBA) to identify needs and barriers to PrEP care, including substance use and behavioral health needs; adherence goal(s); and methods to achieve adherence. PrEP (Truvada, Descovy, Cabotegravir) and clinic options are discussed. Per current state-of-the-field recommendations, participants are guided to receive same-day PrEP linkage to their chosen clinic, with the goal of PrEP initiation within the first week of enrollment. In Sessions 2-5, PrEP navigators use the information from the NBA to help the participant overcome barriers to PrEP adherence, and work with participants to address their SUD and need for additional auxiliary services. A shorter version of the NBA (NBA-Lite) is administered at the beginning of Sessions 2-5 as a check-in, and to assess progress through the PrEP Care Continuum; client-centered treatment plans are reviewed and revised as needed. In the ASK-PrEP sessions, client-centered dialogical strategies premised on RAA: 1) identify barriers to PrEP, including substance use; 2) identify participants' readiness to address their SUD and link into other auxiliary needed services; and 3) increase participants' skills and self-efficacy in working with PrEP providers and other social service and treatment facilities. Using a client-centered approach, the PrEP navigator works to link participants into SUD treatment and other ancillary behavioral health and support services, according to their unique barriers, with the ultimate goal of PrEP initiation, adherence, and persistence; services may include mental healthcare, counseling for intimate partner violence, food insecurity, housing instability, hormone therapy. Discussions of PrEP adherence, reductions in substance use and/or substance use treatment, and other behavioral health concerns are discussed throughout the 5 sessions. A key feature of the study is the tailoring of PrEP navigation and text-messaging support to TW/MSM with a SUD.

The text-messaging support component of ASK-PrEP is based in SST. One PrEP support text message is transmitted weekly on Wednesday afternoon between 3:00 - 6:00, participants may choose to have the text messages delivered via cell phone or email. To maintain interest and enthusiasm for the intervention, participants receive TW- or MSM-specific messages, and never receive the same message twice.

Contingency Management is based on behavioral economics. Non-responders are stepped and re-randomized to CM, either in concert with ASK-PrEP, or alone. At the first CM session, a RA provides a 15-minute orientation to the CM procedures, which includes an explanation of the progressive contingency schedule. Thereafter, participants meet with the RA thrice weekly to provide a urine sample. Participants receive a voucher-based escalating reinforcement schedule. Successive urine samples that are nonreactive for the metabolites of their identified SUD will escalate their voucher point value. Each three consecutive nonreactive urine samples will receive bonus voucher points. A reactive urine sample will place the participant at the initial voucher point value; however, a rapid reset procedure allows participants to return to their place in the escalating schedule following three consecutive nonreactive urine samples. Voucher points can be redeemed at any time during the study for goods or services that promote a pro-social and healthy lifestyle.

Participants stepped and re-randomized into ASK-PrEP+CM receive the same ASK-PrEP and CM interventions (described above), but in concert to increase intensity and address both SUD and PrEP initiation, adherence and persistence.

The Standard of Care (SOC) arm provides PrEP education, information, and referrals. Those randomized to the SOC arm will receive an approximate 20-30-minute educational session on PrEP, and will be given a PrEP pamphlet and list of clinics that provide PrEP in Los Angeles County (LAC). The same educational session will be repeated following the 3-month follow-up assessment visit.