David Magnuson, Trevor Hawkins, Robertino Mera Adolescent Use of Truvada (FTC/TDF) for HIV Pre-Exposure Prophylaxis (PrEP) in the United States: (2012-2017) David Magnuson, Trevor Hawkins, Robertino Mera Gilead Sciences Inc., Foster City, CA USA

Disclosures All authors are employees and shareholders of Gilead Sciences, Inc. This study was funded by Gilead Sciences, Inc.

Introduction FTC/TDF has been approved for HIV Pre-exposure Prophylaxis (PrEP) in adults at high risk of sexually acquired HIV infection in the United States (US), European Union (EU) and at least 19 other countries In 2016, there were 37,782 new HIV diagnoses in the US 8,451 (21%) new HIV infections were in individuals aged 13 – 24 years 6,848 (81%) were in young gay/bisexual men1 There is limited data on the use of FTC/TDF for HIV PrEP in adolescents in the US ATN 113, a study of HIV PrEP in 79 MSM aged 15 – 17 years in the US, demonstrated good overall safety and acceptability but a high HIV incidence and poor retention in care CHAMPS PlusPills, a study of HIV PrEP adolescents aged 15 – 19 years (99 females, 49 males) in South Africa demonstrated PrEP was well tolerated but that PrEP usage and adherence diminished over time Challenges for PrEP update in adolescents in the US include stigma, the need for parental consent in some states, lack of insurance coverage, the potential disclosure of confidential information on the parents’ insurance bill and difficulties in adherence with a high rate of discontinuation compared to older adults Use in adolescents weighing at least 35 Kg was approved in the EU on 05 February 2018 and in the US on 15 May 2018 References: 1 – Division of HIV/AIDS Prevention, CDC, April 2018

Objectives To describe the real world use of FTC/TDF for HIV PrEP in adolescents (12 – 24 years) in the US over 6 years, from January 2012 to December 2017 To evaluate the differences in demographics, treating physicians for adolescents who prescribed FTC/TDF for HIV PrEP, and payment source

Study Design Data Source: National, electronic pharmacy claims data collected from at least 80% of all US retail pharmacies All data was de-identified, and included prescription refill data, medical claims and procedures, and individual demographics limited to age and sex, and provider specialty A validated algorithm identified FTC/TDF for HIV PrEP use by excluding FTC/TDF use for HIV treatment, post-exposure prophylaxis (PEP), and off-label chronic hepatitis B treatment1 Sensitivity 99.6% and Specificity 87.0% References: 1 – R Mera-Giler, et al. National HIV Prevention Conference, Dec 2015, Atlanta, GA

All Individuals Starting FTC/TDF for PrEP in US, 2012 – 2017 6-YearTotal: 177,223 25 and older: 149,893 (84.6%) 12 – 24 : 27,330 (15.4%) Proportion 12 – 24 years 17.0% 17.8% 15.1% 14.6% 13.8% 16.9%

Adolescents Starting FTC/TDF for PrEP in US, 2012 – 2017 6-YearTotal: 27,330 18 – 24: 24,740 (90.5%) 12 – 17: 2,590 (9.5%) Proportion 12 – 17 years 19.8% 21.6% 14.8% 12.3% 3.9% 3.9%

Comparison of Adolescent Males and Females Starting FTC/TDF for PrEP Proportion of Males and Females Numbers of Males and Females Age / Sex 12 13 14 15 16 17 18 19 20 21 22 23 24 M 32 56 93 209 598 1,298 1,776 2,367 3,231 4,296 5,069 F 64 186 352 502 516 542 664 723 771 827 923 1,045 1,152 Total 86 202 384 558 609 751 1,262 2,021 2,547 3,194 4,154 5,341 6,221

Common Prescribers of FTC/TDF for PrEP by Age Category 21% 13% 38% 2% 4% 22% 12% 39% 6% 14% 11% 18% 7% 38% 2% 24% 13% 16% For ages 12-17, pediatricians are the leading prescribers for FTC/TDF for PrEP; and females have a higher proportion by EM (22% vs. 15%) and males have a higher proportion by FP (11% vs. 25%) (p<0.0001) For both ages 18-24 and ≥25, FP and IM are the leading prescribers for FTC/TDF for PrEP; and females have a higher proportion by EM and males have a higher proportion by FP and IM (p<0.0001)

Payment Methods for FTC/TDF for PrEP by Age Category For ages 12-17, Medicaid accounted for 59% of payments for FTC/TDF for PrEP For both ages 18-24 and ≥25, commercial insurance became the primary payment method for FTC/TDF for PrEP

Limitations Claims data only indicates when a prescription was filled and not that the person took the medication Claims data does not contain dosing information (e.g., daily dosing or on- demand dosing) Claims data does not contain information on race/ethnicity, risk factors for HIV, or transgender status Claims data does not include data from closed health care systems (e.g. Kaiser), Veteran’s Administration, colleges/universities, and active duty military health care

Conclusions This retrospective analysis of FTC/TDF for PrEP usage in the US revealed that adolescents < 24 years accounted for 15.4% of FTC/TDF for PrEP usage, and adolescents < 18 years accounted for only 1.5% of FTC/TDF for PrEP usage For adolescents < 18 years, females accounted for 83.5% of usage. For older adolescents 18 – 24 years, FTC/TDF for PrEP is predominately used by males (84.2%) Pediatricians are the most common prescribers for adolescents < 18 years of age Recent approval in the US and the EU to expand the indication for FTC/TDF for HIV PrEP to include adolescents > 35 kg may improve access to PrEP for adolescents There remains an important unmet need to improve awareness and engagement in HIV prevention for adolescents and young adults at risk for HIV

Acknowledgments Thanks to all the young people and their health care providers who contributed data for this analysis