What is the best PrEP (Pre-Exposure Prophylaxis) regimen for a 19-year-old MSM (Men who have Sex with Men) with a history of difficulty adhering to daily oral medications and high-risk sexual behaviors?

Cabotegravir Long-Acting Injectable is the Best PrEP Option for This Patient

For this 19-year-old MSM patient with documented difficulty adhering to daily oral medications and high-risk sexual behaviors, cabotegravir long-acting injectable 600 mg/3 mL intramuscularly every month × 2 doses, then every 2 months is the most appropriate PrEP regimen.

Patient Risk Assessment

This patient has several high-risk factors that make him an excellent candidate for PrEP:

• MSM with 10 male sexual partners in the past month
• Engages in condomless receptive anal sex (one of the highest risk behaviors)
• Positive rectal chlamydia test (indicating ongoing STI risk)
• Previously discontinued oral PrEP due to adherence difficulties
• Self-reported difficulty remembering to take daily medications

Rationale for Injectable Cabotegravir

1. Adherence Considerations:

   • The patient has explicitly demonstrated poor adherence to daily oral medications, both with previous PrEP and current allergy medication
   • Injectable cabotegravir eliminates the need for daily pill-taking, addressing his primary barrier to successful PrEP 1, 2
   • The patient has demonstrated good adherence to physician appointments, suggesting he can reliably attend injection visits

2. Efficacy in MSM Population:

   • Cabotegravir injectable PrEP is highly effective in MSM populations with an evidence rating of AIa 2
   • The FDA has approved cabotegravir for PrEP in adults and adolescents weighing at least 35 kg who are at risk for HIV-1 acquisition 3

3. Dosing Schedule:

   • Initial dosing: 600 mg/3 mL intramuscularly every month × 2 doses
   • Maintenance: 600 mg/3 mL intramuscularly every 2 months 1, 3
   • This schedule aligns with the patient's demonstrated ability to keep medical appointments

Implementation Considerations

1. Pre-Initiation Assessment:

   • The patient has already completed appropriate baseline testing:
     • Negative HIV fourth-generation test
     • Undetectable HIV RNA test
     • STI screening (positive for rectal chlamydia)

2. Oral Lead-In Option:

   • An oral lead-in with cabotegravir can be considered to assess tolerability before the first injection 3
   • However, given the patient's documented difficulty with daily pills, a direct-to-injection approach may be reasonable, as studies have shown similar virologic outcomes with or without oral lead-in 3

3. Monitoring Requirements:

   • HIV testing should be performed at each visit before administering the injection 1
   • Quarterly STI screening is recommended given his high-risk behaviors 1, 2
   • Appropriate treatment for his rectal chlamydia infection should be provided

Alternative Options and Why They're Less Optimal

1. Emtricitabine/tenofovir disoproxil fumarate (TDF/FTC):

   • Despite being effective with an evidence rating of AIa 2, the patient has already failed this regimen due to adherence issues
   • Daily dosing requirement makes this incompatible with the patient's demonstrated adherence patterns

2. Emtricitabine/tenofovir alafenamide (TAF/FTC):

   • While TAF has a better renal and bone safety profile than TDF 2, it still requires daily dosing
   • The patient's primary barrier is adherence to daily medications, which would persist with this option

3. On-demand (2-1-1) PrEP:

   • While effective for MSM 4, this regimen requires even more complex adherence patterns and planning around sexual activity
   • Given the patient's difficulty with daily medications, the more complex dosing schedule would likely lead to failure

Risk Reduction Counseling

In addition to starting cabotegravir injectable PrEP:

• Provide condoms and counseling on consistent condom use
• Discuss STI prevention strategies given his positive rectal chlamydia test
• Schedule regular STI screening every 3 months
• Establish a plan for HIV testing before each injection

By choosing cabotegravir long-acting injectable, we address this patient's specific adherence barriers while providing highly effective HIV prevention for his high-risk sexual behaviors.