Clinical trial NCT03126370
Conditions: Hepatitis C HIV Coinfection
Sponsor: University of Colorado, Denver
Start date: 2018-01-08; Completion date: 2019-10-01
Enrollment: 10 participants; Allocation: NA; Intervention model: SINGLE_GROUP

Brief summary:
This study will evaluate the effect of ledipasvir/sofosbuvir (LDV/SOF) treatment on the pharmacokinetics (PK) and renal safety of tenofovir in the form of tenofovir alafenamide (TAF). Subjects living with human immunodeficiency virus (HIV) who are receiving tenofovir-based antiretroviral therapy (in the form of tenofovir disoproxil fumarate \[TDF\]), and are also taking a ritonavir- or cobicistat-boosted protease inhibitor will be invited to participate.

The study will consist of five visits: a screening visit, three abbreviated 4-hour pharmacokinetic visits, and one end-of-study follow-up visit.

Subjects will also be asked to use a Wisepill device, which will track medication adherence throughout the study.

Detailed description:

Arms: arm 1: Participants who are already taking tenofovir disoproxil fumarate 300 mg (in the form of Viread or Truvada) in combination with either a ritonavir- or cobicistat-boosted protease inhibitor for HIV treatment will continue to take their prescribed treatment for 12 weeks after enrollment.

Participants will be switched from tenofovir disoproxil fumarate to tenofovir alafenamide (TAF) 25 mg/emtricitabine (FTC) 200 mg (Descovy) with a boosted protease inhibitor for the next 12 weeks.

After taking TAF/FTC for 12 weeks, participants will then start taking ledipasvir 90mg/sofosbuvir 400mg (LDV/SOV, Harvoni) in combination with TAF/FTC and a boosted protease inhibitor for 4 weeks.

Participants will then return to taking TAF/FTC with a boosted protease inhibitor for the final 12 weeks of the study.
Interventions: intervention 1: TDF with a boosted protease inhibitor intervention 2: TAF with a boosted protease inhibitor intervention 3: TAF with a boosted protease inhibitor and LDV/SOF
Intervention descriptions: intervention 1: Participants who are already taking tenofovir disoproxil fumarate 300 mg (in the form of Viread or Truvada) in combination with either a ritonavir- or cobicistat-boosted protease inhibitor for HIV treatment will continue to take their prescribed treatment for 12 weeks after enrollment.

Other: Blood draws for tenofovir PK, renal function assessment intervention 2: Participants will be switched from tenofovir disoproxil fumarate to tenofovir alafenamide 25 mg/emtricitabine 200 mg with a boosted protease inhibitor.

Other: Blood draws for tenofovir PK, renal function assessment intervention 3: After taking tenofovir alafenamide/emtricitabine for 12 weeks, participants will then start taking ledipasvir 90 mg/sofosbuvir 400 mg (Harvoni) in combination with the tenofovir alafenamide 25 mg/emtricitabine 200 mg (Descovy) and a boosted protease inhibitor for 4 weeks. Subjects will then return to taking tenofovir alafenamide 25 mg/emtricitabine 200 mg (Descovy) and a boosted protease inhibitor for the final 12 weeks.

Other: Blood draws for tenofovir PK, renal function assessment

Protocol documents:
Prot_SAP_000.pdf: 
 
 
Effects of Ledipasvir/Sofosbuvir on the 
Pharmacokinetics and Renal Safety of 
Tenofovir Alafenamide (TAF) 
 
NCT03126370 
 
Protocol & Statistical Analysis Plan 
 
Version 03.29.2018


 
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Protocol #: 17-0490 
Project Title: 
Effects of ledipasvir/sofosbuvir treatment on the pharmacokinetics and 
renal safety of tenofovir alafenamide (TAF) 
 
 
 
Principal Investigator:  Jennifer J. Kiser, PharmD 
Version Number:  
3.0 
Version Date:  
03/29/2018 
 
 
 
 
 
  
 
 
I. 
Hypotheses and Specific Aims:   
Hypothesis:  
1. Tenofovir plasma concentrations will be lower, tenofovir diphosphate 
concentrations in peripheral blood mononuclear cells will be higher, and 
tenofovir diphosphate concentrations in red blood cells (measured as dried 
blood spots, DBS) will be lower with tenofovir alafenamide relative to tenofovir 
disoproxil fumarate.   
2. Tenofovir plasma and intracellular tenofovir diphosphate concentrations will 
increase when tenofovir alafenamide is co-administered with 
ledipasvir/sofosbuvir relative to TAF alone.  
3. Markers of renal function (e.g. CrCl, urinary retinol binding protein/creatinine 
ratio and urinary beta-2 microglobulin/creatinine ratio) will not change when 
tenofovir alafenamide is coadministered with ledipasvir/sofosbuvir.  
 
Primary Aims: 
1. Compare the area under the concentration time curve over the dosing interval 
(AUC0-24) of tenofovir in plasma when switched from tenofovir disoproxil 
fumarate (TDF) (Phase 1) to tenofovir alafenamide (TAF 25mg) (Phase 2), and 
compare the AUC0-24 of tenofovir in plasma given as TDF (Phase 1) to  
tenofovir in plasma in the form of TAF 25mg concomitantly with ledipasvir 
(LDV)/sofosbuvir (SOF) (Phase 3) 
2. Compare TFV-DP in PBMCs between TDF (Phase 1) and TAF 25mg (Phase 
2) and between TDF (Phase 1) and TAF 25mg plus LDV/SOF (Phase 3) 
 
Secondary Aims: 
1. Compare TFV-DP in DBS between TDF (Phase 1) and TAF 25mg (Phase 2) 
and between TDF (Phase 1) and TAF 25mg plus LDV/SOF (Phase 3) 
2. Compare CrCl, urinary retinol binding protein/creatinine ratio, urinary beta-2 
microglobulin/creatinine ratio between TDF (Phase 1) and TAF 25mg (Phase 
2) and between TDF (Phase 1) and TAF 25mg plus LDV/SOF (Phase 3) 
 
 
II. 
Background and Significance:  
 
Hepatitis C virus (HCV) infection is common among persons infected with HIV due to their shared 
routes of transmission.(1) On average, about 30% of individuals living with HIV are co-infected with 
HCV. HCV is associated with an increased liver-diseases-related morbidity and mortality in persons 
with HIV.(2) Thus, there is a great need to treat HCV in individuals co-infected with HIV.  
 
 
COMIRB Protocol 
COLORADO MULTIPLE INSTITUTIONAL REVIEW BOARD 
CAMPUS BOX F-490    TELEPHONE:  303-724-1055  Fax:  303-724-0990 
 
 


 
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Direct-acting antiviral agents (DAAs) have revolutionized the treatment of HCV, but drug 
interactions remain a substantial challenge.(3, 4)  Ledipasvir (LDV) is an inhibitor of the HCV NS5A 
enzyme. Sofosbuvir (SOF) is an inhibitor of the HCV NS5B polymerase enzyme. These drugs are 
co-formulated in a single tablet (Harvoni®, Gilead Sciences, Foster City, CA) for once daily 
administration. Just 12 weeks of LDV/SOF has achieved cure rates of >95% in HCV treatment 
naïve and treatment experienced patients including in patients coinfected with HIV.(5, 6) LDV/SOF 
is one of the preferred treatment options for HCV because it is highly efficacious, well tolerated, 
has a low pill burden, a short treatment duration of between 8 and 24 weeks, and a low potential for 
drug interactions with antiretroviral agents. The main concern with use of LDV/SOF in co-infected 
patients is that LDV/SOF can raise concentrations of the HIV drug tenofovir. Tenofovir disoproxil 
fumarate (TDF) is one of the most widely prescribed antiretroviral agents. It is a well-tolerated drug, 
but its use has been shown to be associated with renal toxicity including declines in glomerular 
filtration rate, proximal tubular damage, and acute kidney injury.(7-9) Studies suggest the renal 
toxicities from TDF are concentration-dependent (i.e., higher tenofovir concentrations are 
associated with a greater risk for renal toxicity).(10) LDV/SOF, when given concomitantly with TDF 
and a ritonavir-boosted protease inhibitor, has been shown to increase the tenofovir area under the 
concentration time curve (AUCtau) in healthy volunteers to levels that exceed the tenofovir levels 
for which there is established safety data (Figure 1).(11) When patients on antiretroviral regimens 
that include TDF and a booster are treated with LDV/SOF, they have a “double whammy” in terms 
of the increase in tenofovir exposures.  
 
Figure 1.  Tenofovir area under the concentration time curve (AUCtau) in plasma with 
various antiretroviral agents in the presence and absence of LDV/SOF in studies of healthy 
volunteers. The upper range of tenofovir exposures observed in healthy volunteers given 
the combination of LDV/SOF, tenofovir disoproxil fumarate, and a ritonavir-boosted 
protease inhibitor (either ritonavir-booted atazanavir or darunavir) exceeds tenofovir 
exposures with established safety data.   
 
 
 
EFV=efavirenz; RPV=rilpivirine; 
ATR=the fixed dose combination 
product of tenofovir disoproxil 
fumarate, emtricitabine, and  
efavirenz; CPA=the fixed dose 
combination product of tenofovir 
disoproxil fumarate, 
emtricitabine, and rilpivirine; 
FPV=fosamprenavir; 
SQV=ritonavir-boosted 
saquinavir; LPV/r=ritonavir-
boosted lopinavir; ATV=ritonavir-
boosted atazanavir 
DRV=ritonavir-boosted darunavir 
 
There is a new formulation of tenofovir called tenofovir alafenamide (TAF) which provides a lower 
risk of interactions and less renal toxicity. Because it circulates predominantly in pro-drug form, 
TAF maintains 90% lower circulating plasma tenofovir levels compared to TDF.(12, 13) TAF is also 
not a substrate for renal uptake transporters. Thus, TAF is thought to have a significantly reduced 
potential for renal toxicities.(12, 13)  TAF is a very reasonable alternative to TDF in individuals on 
ritonavir or cobicistat who require HCV treatment with LDV/SOF, but there are currently no data 
evaluating the pharmacokinetics and safety of the combination of LDV/SOF, TAF and a ritonavir or 
cobicistat-boosted protease inhibitor when dosed as 25mg of TAF. TAF was FDA approved in two 
different strengths, 10mg which is only available co-formulated with elvitegravir, cobicistat, 
emtricitabine and tenofovir alafenamide 10mg (Genvoya®, Gilead Sciences, Foster City, CA) and 
25mg which is co-formulated with emtricitabine and tenofovir alafenamide 25mg (Descovy®, 
Gilead Sciences, Foster City, CA). While favorable pharmacokinetic data are available on the 
interaction between elvitegravir, cobicistat, emtricitabine and tenofovir alafenamide 10mg with 


 
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LDV/SOF in healthy volunteers(14), there is an absence of data with ritonavir-boosted protease 
inhibitors and with the 25mg strength of TAF.  
 
 
There are several alternatives to LDV/SOF for HCV treatment (e.g., sofosbuvir plus the HCV NS5A 
inhibitor, velpatasvir (a combination referred to as SOF/VEL), or Zepatier® which contains elbasvir, 
a hepatitis C virus (HCV) NS5A inhibitor, and grazoprevir, an HCV NS3/4A protease inhibitor. All of 
these alternatives have drawbacks clinically. Additionally, simply avoiding the use of ritonavir or 
cobicistat with TDF as a component of antiretroviral therapy is not possible in all patients.(15, 16) 
Thus, patients may receive the combination of LDV/SOF, tenofovir, and ritonavir or cobicistat and 
data are desperately needed to determine the magnitude of the interaction between tenofovir and 
LDV/SOF and examine potential alternatives, such as TAF, that might be renal-sparing. The 
purpose of this study is to determine the magnitude of the interaction between tenofovir in the form 
of TAF and LDV/SOF and examine the effect of this interaction on renal function. 
 
Several renal biomarkers have routinely been used in clinical research, specifically in HIV infected 
patients to determine the presence or absence of proximal tubular dysfunction.(12-14) An increase 
in low molecular weight proteins such as urinary retinol binding protein and beta-2 microglobulin 
have been shown to be indicative of tubular dysfunction, with the urinary concentration being 
correlated with the severity of the tubular dysfunction.(12) Early studies in HIV infected individuals 
have shown that the presence of HIV alone increases the urinary concentrations of retinol binding 
protein and beta-2 microglobulin by 3-10 fold when compared to healthy controls(15) and that 
patients who have tenofovir-induced Fanconi syndrome tend to have very high levels of these 
markers.(16) Both retinol binding protein and beta-2 microglobulin have been used to assess renal 
proximal tubule injury in HIV infected individuals who are taking tenofovir, thus we have chosen to 
use these biomarkers to study the renal safety of tenofovir alafenamide and LDV/SOF. 
 
 
Good adherence to study medications is important in 
the context of a pharmacokinetic / drug interaction 
study. There are a variety of tools that can be used to 
assess adherence including pill counts, refill histories, 
digital ingestible sensor, and electronic monitoring. To 
monitor participants adherence in this study, we will 
use the Wisepill portable medication dispenser 
(Wisepill Technologies, Cape Town, South Africa) or 
directly observed therapy via video-streaming methods 
(e.g., FaceTime, Google Hangouts, TimeStamp). 
Wisepill transmits a cellular signal (real-time) when 
opened to a central management system (Wisepill 
Web Server). The dispenser is slightly larger than a 
cell phone and small enough to fit in a pocket. The 
battery lasts 4 months without charging. Participants 
will switch out 7-day medication cartridge once weekly 
- which takes seconds to perform.(17) We are using this device in an ongoing study of LDV/SOF in 
HIV/HCV coinfected persons who use drugs. Directly observed therapy via video-streaming 
methods may be used in place of the Wisepill device, approaches of which have also been used in 
multiple studies through the CAVP laboratory.  
 
III. 
Preliminary Studies/Progress Report:   
 
Analytical approaches to be used in this research: 
Tenofovir will be quantified in plasma using a validated LC-MS/MS method with a  dynamic range 
of 10ng/mL to 1500 ng/mL.(18) Intracellular tenofovir diphosphate (TFV-DP) will be measured in 


 
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peripheral blood mononuclear cells (PBMC) using a validated LC-MS/MS method with a dynamic 
range of 2.5 fmol/sample to 2000 fmol/sample.(19) 
 
Our group is well-versed in these techniques as shown in the following studies: 
We have been performing studies on the pharmacology of tenofovir for more than 10 years, (18, 
20-25) and recently identified a drug interaction between individuals taking TDF in combination with 
SOF/ribavirin.(26)  
 
As Figure 2 indicates, TFV-DP was increased 4-fold in dried blood spots (DBS) after 12 weeks of 
SOF and ribavirin (RBV) treatment. This interaction was also observed in peripheral blood 
mononuclear cells (PBMC), where TFV-DP concentrations at week 12 of SOF/RBV treatment were 
double those observed before (study entry) 
and 12 weeks following the completion of 
SOF/RBV treatment.(26) 
 
Clinical Considerations: 
We have established collaborations with 
study co-investigator Dr. Jose Castillo 
Mancilla who cares for HIV-positive patients 
in the Infectious Disease Group Practice 
(IDGP) Clinic at the University of Colorado 
Hospital. Dr. Castillo-Mancilla recently 
completed a large study in HIV-infected 
patients on TDF in the IDGP clinic, thus he 
has a research-relationship with potentially 
eligible participants.    
 
IV. 
Research Methods 
 
A. Outcome Measure(s):   
Primary Outcome: 
1. Area under the concentration-time curve over the dosing interval (AUC0-24) of 
tenofovir in plasma when switched from TDF (Phase 1) to TAF 25mg (Phase 2), 
and once on TAF 25mg, compare the AUC0-24 of tenofovir in plasma given as 
TDF (Phase 1) to TAF 25mg concomitantly with LDV/SOF (Phase 3) 
2. TFV-DP in PBMCs between TDF (Phase 1) and TAF 25mg (Phase 2) and 
between TDF (Phase 1) and TAF 25mg plus LDV/SOF (Phase 3) 
 
Secondary Outcomes: 
1. Compare TFV-DP in DBS between TDF (Phase 1) and TAF 25mg (Phase 2) and 
between TDF (Phase 1) and TAF 25mg plus LDV/SOF (Phase 3) 
2. Compare CrCl, urinary retinol binding protein/creatinine ratio, urinary beta-2 
microglobulin/creatinine ratio between TDF (Phase 1) and TAF 25mg (Phase 2) 
and between TDF (Phase 1) and TAF 25mg plus LDV/SOF (Phase 3) 
 
B. Description of Population to be Enrolled:   
This study will enroll HIV monoinfected individuals receiving TDF + a ritonavir or cobicistat 
boosted protease inhibitor (PI).  TAF 25mg/emtricitabine 200mg and LDV 90mg/SOF 400mg 
will be provided by the study. Study subjects will also be given a Wisepill device which is a 
pillbox that monitors adherence by tracking when the pillbox is opened. 
 
Inclusion criteria:  
1. Participants must be between 18-70 years of age  
2. Have been taking TDF and a ritonavir- or cobicistat-boosted PI, as part of standard 
care for treatment of HIV 


 
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Exclusion criteria:  
1. Glomerular filtration rate < 30 mL/min/1.73 m2  
2. Pregnant or planning pregnancy  
3. Breastfeeding 
4. Any laboratory value or uncontrolled medical conditions, including mental health, that, 
in the opinion of the investigators, would interfere with participant safety or protocol 
compliance such as but not limited to, heart disease, autoimmune disorders, low bone 
density, drug/alcohol addiction, and/or cancer 
5. Signs or symptoms of decompensated liver disease (i.e., ascites, history of esophageal 
variceal bleeding, hepatic encephalopathy)  
6. Hepatitis B virus infection 
7. Pathologic fracture or other risk factors of bone loss or osteoporosis 
8. Medications not recommended per the LDV/SOF or F/TAF 25mg prescribing 
information that at the discretion of the investigator may cause unwanted drug 
interactions (e.g., Pgp inducers such as tipranavir) 
9. Unwillingness or inability to comply with study procedures, including the wisepill device 
and clinic visits 
10. Chronic HCV infection (i.e., detectable HCV RNA)


 
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C. Study Design and Research Methods   
 


 
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Up to fifteen HIV monoinfected individuals already taking TDF + a ritonavir or cobicistat boosted PI 
will be invited to participate in this study. Participants from the University of Colorado Infectious 
Diseases Group Practice (IDGP) clinic and Denver Health will be targeted for enrollment. 
Participants may also be referred by other providers in the greater Denver-area.  
 
The study consists of five study visits: a screening visit, three abbreviated 5-hour pharmacokinetic 
visits, and one “off study” visit of Descovy (see schedule of events). The study visits will take place 
in the IDGP Clinic at University of Colorado Hospital or the University of Colorado Clinical & 
Translational Research Center (CTRC). Subjects will receive $75 for the baseline visit, $225 for 
each 5-hour intensive pharmacokinetic visit, and $75 for the end-of-study visit for a total of $825, 
and free F/TAF and LDV/SOF throughout the study. 
 
Real-Time Adherence Monitoring: Participants will be provided the Wisepill portable medication 
dispenser or counseled on video-streaming methods for directly observed therapy during Visit 1. In 
those receiving the Wisepill device, on a weekly basis, participants will fill the 7-day cartridges with 
their ritonavir or cobicistat-boosted protease inhibitor plus TDF (Phase 1), F/TAF (Phase 2), or 
F/TAF and LDV/SOF (Phase 3). Each Wisepill device contains a SIM card with 3G wireless 
capabilities that records and transmits the time and date of opening the medication dispenser. The 
SIM card gives each device a unique signal. Power failure with the Wisepill device is mitigated by 
a signaling subsystem which maintains data for later transmission if connectively is lost. In addition 
to recording device openings, the Wisepill signal reports the remaining battery power for the 
device and airtime left on the SIM card so there is typically advanced notice of potential 
problems.(17) For the video-streaming methods, participants that already own a smartphone will 
be shown how to install and use the video-streaming application of their choice (e.g., FaceTime, 
Google Hangouts, TimeStamp). For those who do not own a smartphone, the study team will 
provide one with the video-streaming methods pre-installed, and participants will be educated on 
the appropriate use of the device. Participants will then record or livestream ingestion of their 
medications daily for review by study personnel. Study personnel will then record the date and 
time of drug ingestion. 


 
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Visit 1 (Week 0): Screening Visit 
This visit will take place in either the IDGP clinic or the CTRC. During this visit, subject’s informed 
consent will be conducted, and subjects will have the opportunity to sign the informed consent. 
Following informed consent subjects will have their blood drawn for safety and eligibility specifically 
obtaining a HIV 1-RNA, HCV-RNA, CBC and CMP. Vitals will be collected. Women of childbearing 
potential will have a urine pregnancy test. Those that qualify for the study will receive a Wisepill 
device for tracking adherence, or be instructed on the use of video DOT methods. Participants that 
are initially started on the DOT video-streaming methods may be transitioned to the Wisepill device 
at a subsequent study visit. 
 
Visit 2 (Week 12, ±3 days): Phase 1 Measurements  
This visit will take place only after the participant has been taking TDF for 12 weeks. 
Measurements during this visit will include: an abbreviated PK visit (pre dose, 1 hour and 4 hour 
post dose samples will be obtained) as well as safety labs, renal biomarkers, HIV-1 RNA. A whole 
blood sample for DNA isolation will also be collected. Vitals will be collected. Women of 
childbearing potential will have a urine pregnancy test. Participants will be instructed on switching 
from TDF to F/TAF 25.   
 
Visit 3 (Week 24, ±3 days): Phase 2 Measurements 
Twelve weeks following the switch to F/TAF 25, subjects will undergo the Phase 2 measurements. 
This visit will take place after the participant has been taking F/TAF 25mg for 12 weeks. 
Measurements during this visit will include: an abbreviated PK visit (pre dose, 1 hour and 4 hour 
post dose samples will be obtained) as well as safety labs, renal biomarkers, HCV-RNA, and an 
HIV-1 RNA. Vitals will be collected. Women of childbearing potential will have a urine pregnancy 
test. 4 weeks of LDV/SOF will be provided and instructions regarding when to initiate taking 
LDV/SOF   
 
Visit 4 (Week 28, ±3 days): Phase 3 Measurements 
After taking LDV/SOF for 4 weeks, subjects will undergo the Phase 3 measurements which will 
include: an abbreviated PK visit (pre dose, 1 hour and 4 hour post dose samples will be obtained) 
as well as safety labs, renal biomarkers, and an HIV-1 RNA. Vitals will be collected. 
 
Visit 5 (Week 40, ±3 days): Off-Study 12 weeks after completion of LDV/SOF 
This visit will take place in either the IDGP clinic or the CTRC and will assess how the patient is 
doing following completion of LDV/SOF. At this visit, safety labs will be obtained evaluating HIV-1 
RNA, CBC, CMP, TFV in plasma, TFV-DP in PBMC’s and RBCs and renal safety markers.  
 


 
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Schedule of Events (SOC = standard of care) 
 
 
Visit 1: 
Screening 
Visit 2:  
TDF for 12 weeks 
“Phase 1” 
Visit 3:  
F/TAF for 12 weeks 
“ Phase 2” 
Visit 4:  
F/TAF + LDV/SOF 
for 4 weeks 
“Phase 3” 
Visit 5:  
12 weeks after 
completion of 
LDV/SOF 
“Off Study” 
Visit Type 
Research 
Research 
Research 
Research 
Research 
Informed Consent 
X 
 
 
 
 
Standardized Breakfast 
 
X 
X 
X 
 
Observed Dosing 
 
X 
X 
X 
 
Vitals 
X 
X 
X 
X 
 
PK blood draws at pre dose, 
1 and 4 hours post-dosea 
 
X 
X 
X 
 
Single convenience PK blood 
drawb 
 
 
 
 
X 
hDNA 
 
X 
 
 
 
HIV -1 RNA 
X 
X 
X 
X 
X 
HCV RNA 
X 
 
X 
 
 
CBC 
X 
X 
X 
X 
X 
CMP 
X 
X 
X 
X 
X 
Urinalysis 
(protein: Cr ratio) 
 
X 
X 
X 
X 
Urinary Beta 2-microglobulin: 
Cr ratio) 
 
X 
X 
X 
X 
Urinary retinol binding 
protein/creat ratio 
 
X 
X 
X 
X 
Pregnancy Test (in women of 
childbearing potential) 
X 
X 
X 
 
 
aIncludes SCr for CrCl estimate bTFV in plasma and TFV-DP in PBMCs and DBS will be measured from blood PK samples 


 
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D. Description, Risks and Justification of Procedures and Data Collection Tools: 
 
Description of risks:  
We are collecting blood, urine, genetic, and clinical information from participants through this study 
as well as switching their HIV regimen from TDF to TAF 25mg and using LDV/SOF in HCV 
seronegative individuals. The potential risks associated with study participation are and are 
outlined below:  
1) Blood will be collected from an arm vein. Risks of blood draws include pain when the 
needle or lancet pierces the skin, bruising, and/or infection. We are collecting 24 mL of 
blood at each of the abbreviated pharmacokinetic visits for a total of 72 mL of blood. The 
blood volumes are well below the maximal volumes set for blood donations and clinical 
research of 450 to 550 mL in 8 weeks.  
2) Privacy risk: As with participation in any clinical trial, privacy cannot be guaranteed. This 
study will collect clinical information from patients with HIV infection. The video DOT 
methods may also pose a risk as video sessions may not be encrypted and could be 
decoded and viewed by third parties, in addition to telephone numbers. 
3) Switching from TDF to TAF 25mg. The risks of switching therapy are minimal due to TAF 
25mg having lower renal adverse events. The risk include potential virologic failure (e.g. 
increases in the HIV-1 RNA) or potential adverse reaction to TAF 25mg that was not 
experienced with TDF including: hypersensitivity, gastrointestinal issues or renal failure. 
4) Renal toxicity and adverse events with TDF or TAF 25mg. TDF specifically has been 
shown to cause renal toxicity including declines in glomerular filtration rate, proximal 
tubular damage, and acute kidney injury. The FDA labeling information for TDF and TAF 
25mg list this as a potential risk. Other adverse events from TDF or TAF include: nausea 
(13%), diarrhea (21%), fatigue (14%), and increase in total cholesterol (> 10%).  
5) There are risks associated with Hepatitis C treatment in an HCV seronegative individual. 
These include development of virologic resistance if participants were to become infected 
while taking the medication. This could make future Hepatitis C therapies less effective. 
6) The risks of taking ledipasvir/sofosbuvir include adverse events of the medication such as: 
fatigue (13-18%), headache (11-17%), nausea (6-9%), diarrhea (3-7%), trouble sleeping 
(3-6%) and bilirubin elevations (less than 3%).  
7) Pregnancy. The risk of taking ledipasvir/sofosbuvir, TDF and TAF 25mg while pregnant are 
unknown, thus measures will be taken to not enroll pregnant women and also educate 
subjects on the importance of not becoming pregnant while on study. 
8) Genetic information. This study will collect DNA samples to explore relationships between 
genetic variability in enzymes and transporters that may affect the pharmacokinetics of the 
study drugs being examined in the study. There is a risk that a third party could access this 
information and use it to discriminate against subjects. 
 
Minimizing risks:  
1) Blood draws will be performed by certified and experienced phlebotomists.  
2) Informed Consent: The study will be reviewed and approved by the IRB prior to initiation of 
enrollment. Written documentation of informed consent approval will be present prior to 
initiation of any study related procedures. A consent form will be provided to participants in 
the clinic. Ample time will be allotted for the consenting process, which will take place in a 
private room. Subjects will be encouraged to ask questions and take as much time as 
needed to reach a decision. Subjects will be given a copy of the signed consent document.  
3) Participants will be assigned a unique study identification number (SID). This number will 
be used on case report forms and samples rather than patient identifiers. The link between 
the SID and patient name and any documents (consent form, demographic form, W9, etc.) 
with identifying information will be stored in a locked cabinet in Dr. Kiser’s locked office in 
the Skaggs School of Pharmacy building room 4102.  


 
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4) Video DOT: every effort will be made to protect subjects’ information. Videos will be viewed 
on a password-protected phone, and only the participant’s SID will be programmed into the 
phone. Live-streamed videos will be observed in a private location, and any recorded 
videos sent via text will be erased following appropriate documentation of the date and 
time of drug ingestion.  
5) Participants will be managed by their primary infectious disease doctor and monitored for 
either virologic failure or adverse events that may result from switching from TDF to TAF 
25mg. 
6) For patients taking either TDF or TAF 25mg with a ritonavir or cobicistat-boosted protease 
inhibitor, urine parameters will be assessed every 4 weeks and the tenofovir dose altered 
as indicated for reductions in renal function. Individuals at higher risk for renal toxicity 
(glomerular filtration rate < 30 mL/min/1.73 m2) are excluded from study. Subjects will also 
be discontinued if glomerular filtration rate declines to less than 30 mL/min/1.73 m2. We 
will also follow the Division of AIDS toxicity tables and Grade 3 or higher for Scr (> 1.8 to 
<3.5 x ULN OR Increase of 1.5 to < 2.0 x above baseline) and CrCl (<60 to 30 ml/min or 
ml/min/1.73 m2 OR > 30 to < 50% decrease from baseline) will be reported to Dr. Castillo-
Mancilla within 24 hours for management.  If any other adverse events arise, they will be 
managed per standard of care.  
7) Subjects will be counseled on the importance of reducing the risk of acquiring HCV while 
enrolled in the study (i.e., safe sex practices, use of clean needles, etc.). The importance of 
adherence to Hepatitis C treatment will be stressed to participants to minimize the risk of 
developing viral resistance. Adherence will also be monitored using the Wisepill device.  
8) Adverse events will be monitored as below (Toxicity Management section)   
9) Pregnant women will be excluded from the study and pregnancy tests will be done at 
screening as well as Visits 2 and 3.  
10) Genetic information: the subject will be asked for explicit consent within the ICF to collect a 
genetic sample, and may request for their sample to be withdrawn and destroyed after 
collection. Collected genetic samples will be de-identified and labeled with the subject’s 
SID. Genetic analyses with the subject’s sample will not be included in the patient’s 
medical record and will be kept either in a locked file cabinet or secured server that is only 
available to study personnel.  
 
Toxicity Management  
 
This study is collecting blood and clinical information. Any side effects observed in the course of 
the study will be reported to Dr. Castillo-Mancilla, and managed as per standard of care and the 
toxicity management plan described below:  
 
1. Assessing adverse events. Each subject will be evaluated for clinical and laboratory 
adverse events at each study visit. Dr. Kiser and her study staff will review laboratory 
results daily, and our University hospital clinical laboratory alerts study personnel 
immediately for grossly abnormal clinical laboratory results. All adverse events will be 
graded using the DAIDS tables. The chronicity of the event will be documented as: single 
occurrence, intermittent, or persistent. The date of adverse event onset, cessation, and 
report will also be documented. The relationship to study medication(s) will be documented 
as yes, no, or cannot be ruled out. The action taken will be documented as well (e.g., none, 
study drugs held, study drugs discontinued, additional laboratory tests required, and/or 
medications prescribed to manage the adverse effects). 
2. Adverse event attribution scale. All serious adverse events will be graded as to their 
expectedness and their outcome (i.e., not-related, possibly-related, probably-related, or 
definitely-related to the study protocol). 
3. Reporting adverse events. Any grade 3 or higher clinical adverse events and abnormal 
laboratory results will be reported to Dr. Castillo-Mancilla within 24 hours of the event. 
Adverse events grades ≤2 will be managed by Dr. Castillo-Mancilla. Any adverse event 
that is reported to the PI or her designated research associates by the subject or medical 


 
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staff caring for the subject that is (1) unexpected and related to study drug or study 
treatment or (2) required hospitalization or prolonged hospitalization, caused disability, 
death, a congenital anomaly or birth defect, or was considered life-threatening will be 
documented and reported immediately to the Colorado Multiple Institutional Review Board, 
the University of Colorado Clinical Translational Research Center, and Gilead Sciences.  
 
Individual study stopping criteria  
The study interventions that would differ from standard of care include additional clinic visits, blood 
draws and providing LDV/SOF to individuals without HCV infection. Thus, side effect management 
is at the discretion of the infectious disease provider (e.g. Dr. Castillo-Mancilla). The following 
criteria have been developed to indicate when an individual subject would need to discontinue 
study medications and study participation. 
1. Individual Study Stopping Criteria for all subjects: 
a. Non-adherence with study activities at the discretion of the Investigator   
b. Pregnancy 
c. Decrease of glomerular filtration rate by ≥50%, if glomerular filtration rate is ≤ 60 
mL/min/1.73m2 at time of enrollment 
d. Adverse event for which study team deems HCV treatment or study participation to 
no longer be in subject’s best interests 
e. Threatening to clinic or study personnel 
 
Study Stopping Criteria.  
The rate of serious adverse events in the Phase 3 LDV/SOF trials was 4-6% and in TAF was 3-4%. 
If greater than 10% or 2 patients in a row (whichever is smaller) experience a serious adverse 
event deemed possibly or probably related to LDV/SOF, TAF 25mg treatment or study 
participation, the study will be stopped and the study team will review all safety and laboratory data 
and consider making changes to the study vs. discontinuing the study permanently. 
 
    
E. Potential Scientific Problems:   
We would like complete data for 10 subjects for this study. We plan to recruit the study 
from the University of Colorado IDGP clinic. If after the first 6 months we have not recruited 
5 subjects, we will enlist the assistance of other local HIV providers/clinics (e.g., Denver 
Health, Apex family medicine, Kaiser, Rose Medical Center). 
 
F. Data Analysis Plan:   
 
Analysis Plan. For the primary analysis, Phase 1 will be compared to both Phase 2 and 3. 
Given two comparisons of interest (tenofovir in plasma and TFV-DP in PBMCs), the 
primary comparisons will be performed using a significance level of 0.025. We will enroll 15 
individuals with the goal of having complete data on 10 HIV monoinfected subjects. Given 
the small sample size for primary objectives, we will utilize a Wilcoxon signed-rank non-
parametric test to detect differences in outcomes between phases.  R (http://www.r-
project.org/), GraphPad Prism (La Jolla, CA) and SAS (SAS Institute Inc., Cary NC) 
software will be used for analysis. All power calculations were performed in PASS, NCSS 
software, Kaysville UT. 
 
AIM-1.  AIM-1 is to compare the AUC levels of tenofovir in plasma between Phase 1 and 
Phase 2 and between Phase 1 and Phase 3. Sample size parameters for Phase 1 were 
estimated from AUC0-24 levels of tenofovir in plasma from patients on a TDF + 
lopinavir/ritonavir regimen for a minimum of 4 weeks on study. (25) For these 15 
participants, a geometric mean of 4108 ng*hr/mL was observed with a corresponding loge 
transformed mean (SD) = 8.321 (0.320) used for sample size calculations. 
 


 
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Aim-1 Power: Phase 1 to Phase 2. When patients switch to TAF 25mg during Phase 2, we 
expect 90% lower AUC0-24 levels of tenofovir compared to Phase 1. (12, 13) Conservatively 
doubling the standard deviation from Phase 1 data and using a sample size of 10, we are 
fully powered to detect a 90% decrease in AUC0-24 levels with a significance level of 0.025 
using a two-sided Wilcoxon test assuming that the actual distribution is normal. Powering 
off a lower than expected decrease in AUC0-24 levels, a sample size of 10 achieves ≥ 80% 
power to detect a 50% decrease in AUC0-24 with a significance level of 0.025 using the 
same two-sided Wilcoxon test above.  
 
Aim-1 Power: Phase 1 to Phase 3. During Phase 3, patients who have been on 12 weeks 
of F/TAF 25mg + a ritonavir or cobicistat boosted protease inhibitor (Phase 2) will continue 
on this regimen while LDV/SOF treatment is added. From Phase 2 to Phase 3, we expect a 
27% increase in AUC0-24 levels of tenofovir compared to Phase 2. This results in an overall 
expected decrease in AUC0-24 levels from Phase 1 to Phase 3 of 87% (90% decrease x 
27% increase). With a sample size of 10, a significance level of 0.025 and conservatively 
doubling the standard deviation from Phase 1 data, we are fully powered to detect an 87% 
decrease in AUC0-24 levels using a two-sided Wilcoxon test assuming that the actual 
distribution is normal. Using the same two-sided Wilcoxon test above but powering off a 
lower than expected decrease, a sample size of 10 achieves ≥80% power to detect a 49% 
decrease in AUC0-24 levels from Phase 1 to Phase 3. 
 
AIM-2.  AIM-2 is to compare the TFV-DP in PBMCs between Phase 1 and Phase 2 and 
between Phase 1 and Phase 3. Sample size parameters for TFV-DP in PBMCs for Phase 
1 were estimated from 11 subjects on TDF with a ritonavir-containing antiretroviral regimen 
from Cohort 1 of ACTG 5327. For these individuals, a geometric mean of 74 fmol/million 
cells was observed with corresponding loge transformed mean (SD) = 4.305 (0.529) used 
for sample size calculations. 
 
Aim-2 Power: Phase 1 to Phase 2. Preliminary data for 10 individuals on a TAF 25mg with 
cobicistat regimen was used to estimate levels of TFV-DP in PBMCs for Phase 2.(27) The 
geometric mean for these individuals was 517 fmol/million cells resulting in a difference in 
TFV-DP between Phase 1 and Phase 2 of 1.94 (0.637) on the loge scale, where the 
estimated standard deviation conservatively assumes no correlation of subjects between 
phases. Assuming a two-sided Wilcoxon test with a sample size of 10 and a significance 
level of 0.025, we are fully powered to detect a difference of 443 in geometric means 
between Phase 1 and Phase 2. The power estimate is robust to increased variability, as 
we have greater than 99% power when the standard deviation is doubled in the power 
calculation.  
 
Aim-2 Power: Phase 1 to Phase 3. In Phase 3, LDV/SOF treatment is added to patients 
taking F/TAF 25mg + a ritonavir or cobicistat boosted protease inhibitor. Data on the 
interaction between F/TAF 25mg and cobicistat with LDV/SOF shows an increase in TFV-
DP in PBMCs in healthy volunteers.(14) As we are ≥99% powered under conservative 
estimates from phase 1 to phase 2, we expect to be fully powered from Phase 1 to Phase 
3 due to the larger detectable difference resulting from the addition of LDV/SOF. 
 
Secondary Objectives. Secondary analyses include: 1) compare TFV-DP in DBS 
between Phase 1 and Phase 2 and between Phase 1 and Phase 3; 2) compare CrCL, 
urinary retinol binding protein/creat ratio, urinary beta-2 microglobulin urine per ratio CRT 
between Phases 1 and 2 and between Phases 1 and 3; 3) compare AUC0-24 of tenofovir in 
plasma between Phase 2 and Phase 3; and 4) compare TFV-DP in PBMCs between 
Phase 2 and Phase 3. Friedman’s test and non-parametric methods will be employed. As 
secondary objectives are considered hypothesis generating, p-values will be reported 
unadjusted for multiple comparisons. The percentage of patients achieving SVR will be 
provided.   


 
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G. Summarize Knowledge to be Gained:   
LDV/SOF is the preferred treatment for HCV because it is highly efficacious,   well 
tolerated, has a low pill burden, and a short treatment duration of between 8 and 24 weeks. 
It is a highly desirable treatment option for HIV infected individuals because of its low 
potential for drug interactions with antiretroviral agents. However, the increase in tenofovir 
exposures observed in drug interaction studies in healthy volunteers is a significant 
concern and there is minimal guidance on the appropriate management of patients on 
tenofovir-based antiretroviral therapy initiating LDV/SOF. Through this study, we will 
determine the magnitude of the interaction between tenofovir administered in the form of 
TAF 25mg and LDV/SOF in HIV monoinfected patients and examine the effect of this 
interaction on renal function. 
 
 
 
 
 
 
 
 


 
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