1. 13 th Conference on Retroviruses and Opportunistic Infections February 5-9, 2006 Denver, Colorado Poster No. 781 The Safety of Tenofovir DF for the Treatment of HIV Infection: The First 4 Years M Nelson, 1 D Cooper, 2 R Schooley, 3 C Katlama, 4 J Montaner, 5 S Curtis, 6 L Hsu, 6 B Lu, 6 S Smith, 6 J Rooney, 6 and the Viread Global Expanded Access Program 1 Chelsea and Westminster Hospital, London, UK; 2 University of New South Wales, Sydney, Australia; 3 University of California, San Diego, CA, USA; 4 Pitié-Salpêtrière, Paris, France; 5 University of British Columbia, Vancouver, Canada; 6 Gilead Sciences, Inc., Foster City, CA, USA and Cambridge, UK

2. Nelson M, et al. 13 th CROI, 2006; #781. Introduction Tenofovir disoproxil fumarate (TDF; Viread) is a once daily nucleotide reverse transcriptase inhibitor indicated in combination with other antiretroviral agents for the treatment of HIV-1 infection. TDF was approved in the US in 2001 and in Europe in 2002. Cumulative patient exposure to TDF since first marketing approval is estimated to be 455,392 patient-years of treatment. TDF is administered as a single 300 mg tablet (Viread). The most common adverse events that occurred in patients receiving TDF with other antiretroviral agents in clinical trials were mild to moderate gastrointestinal events, such as diarrhea, vomiting, and nausea. Laboratory abnormalities observed in these studies occurred with similar frequency in the TDF and placebo treated groups. The safety of TDF for the treatment of HIV infection in clinical practice has not been fully characterized. Nephrotoxicity, including renal insufficiency and Fanconi’s syndrome, have been reported to occur infrequently but the incidence, risk factors, and time to resolution remain uncertain.

3. Nelson M, et al. 13 th CROI, 2006; #781. Objective Evaluate the safety profile of TDF for the treatment of HIV infection, as observed in the Viread Global EAP and via spontaneous safety reports submitted to Gilead Drug Safety and Public Health Department through the first 4 years following commercial availability.

4. Nelson M, et al. 13 th CROI, 2006; #781. Methods Viread EAP: Prior to commercial availability, a global expanded access program (EAP) was initiated in March 2001 for HIV-1 infected patients who failed prior HAART and had limited treatment options. To be eligible to participate, patients must have met the following criteria prior to dosing: age ≥ 18 years, confirmed laboratory diagnosis of HIV-1 infection, unable to construct a viable treatment regimen without Viread, had no hematologic, renal, or hepatic dysfunction, not pregnant or breast feeding and agreed to use effective barrier contraceptive method while receiving Viread. Initial study entry criteria included limitations on CD4 counts or HIV RNA at study entry. These specific criteria (CD4 and HIV RNA) were removed shortly after the start of enrollment in all countries.

5. Nelson M, et al. 13 th CROI, 2006; #781. Methods (cont’d) –At total of 10,343 patients were enrolled in the EAP: 654 (Australia), 348 (Belgium), 1,761 (Canada), 1857 (France), 411 (Germany), 12 (Ireland), 553 (Italy), 256 (Netherlands), 58 (Portugal), 576 (Spain), 819 (United Kingdom), and 3,038 (United States). –Data is available on all patients in the Viread EAP for serious adverse events (SAEs). SAEs were tabulated, and SAEs of clinical importance were characterized. Serum creatinines were collected in over 1,600 patients in the Viread EAP. Risk factors for development of graded creatinine abnormalities were determined using mulitvariate logistic regression models. Post marketing safety data: Adverse drug reactions (ADRs), both serious and non-serious received through spontaneous reporting up to April 30, 2005 have been collected and analyzed. Reporting rates for individual serious ADRs (SADRs) have been calculated. Based upon an estimated 455,392 patient-years of exposure to TDF (estimated from sales data).

6. Nelson M, et al. 13 th CROI, 2006; #781. Methods (cont’d) Although reporting rates do not represent the true incidence of SADRs (as post marketing SADRs tend to be underreported and are subject to various reporting biases), the pattern of SADRs reporting in the post-marketing database was compared with the pattern of SAEs reported in the EAP. For patients with renal ADRs the renal events were grouped into relevant categories (renal failure, renal tubulopathy, etc.), and the time to event onset and resolution were calculated. Concomitant risk factors for renal disease were tabulated. For patients with renal ADRs where serum creatinine values were provided, time to onset, median maximal serum creatinine, and time to resolution of serum creatinine were determined.

7. Nelson M, et al. 13 th CROI, 2006; #781. EU & Australia (n = 5,544) Canada (n = 1,761) US (n = 3,038) All EAP (n = 10,343) Age (available data) n = 5,395n = 1,734n = 2,846n = 9,975 Median 41444342 Sex (%) n = 5,452n = 1,744n = 2,855n = 10,051 Male 80899085 Female 20111015 Baseline HIV RNA (log 10 copies/mL) n = 5,269n = 1,469n = 707 a n = 6,738 Median 4.324.384.994.34 Range 1.69, 7.601.69, 6.680.90, 6.921.69, 7.60 Baseline CD4 Count (cells/mm 3 ) n = 5,345n = 1,611n = 846 a n = 6,956 Median 23421090230 Range 0, 1,8500, 2,0600, 1,0160, 2,060 Time on Tenofovir DF (weeks) n = 1,311n = 296n = 1,631N = 3,238 Median 22.622.012.016.1 Summary of Demographic and Baseline Disease Characteristics for the Viread EAP

8. Nelson M, et al. 13 th CROI, 2006; #781. EU & Australia (n = 5,544) Canada (n = 1,761) US (n = 3,038) All EAP (n = 10,343) Person-years of Exposure to TDF 2,5059727483,700 Prior ART (%) n = 4,713n = 1,761n = 3,035n = 9,509 PI 92728486 NNRTI 82607776 NRTI 99818692 PI + NNRTI + NRTI 76537572 ART at Baseline (%) n = 5,385n = 1,511n = 2,633n = 9,529 Lopinavir/ritonavir 54474651 Lamivudine 47564548 Didanosine 34322832 Abacavir 312730 Stavudine 15213121 a. The collection of Baseline HIV RNA and CD4 were no longer required by the protocol shortly after the initiation of the EAP in the US. Summary of Demographic and Baseline Disease Characteristics for the Viread EAP (cont’d)

9. Nelson M, et al. 13 th CROI, 2006; #781. SAEs from EAP a,b and Most Common SARDs from Post Marketing Safety Database c (Excluding SAEs listed in Specific SAE Categories of Interest and Serious Renal Adverse Event Categories) EAP (n = 10,343) (3,700 person years) PM Safety Database (455,392 person years) # of patients (%)Incidence Per 100,000 person years Reporting Rate Per 100,000 person years d Anemia220.25940.9 Asthenia10< 0.12701.3 Diarrhea200.25410.9 Drug Interaction0002.0 Fever420.41,1352.4 Infection Bacterial260.37030.6 Lymphoma like Reaction260.37030.2 Multi-organ Failure4< 0.11081.3

10. Nelson M, et al. 13 th CROI, 2006; #781. A U C ( h g/ mL a.Repeated by  0.1% of patients. b.SAEs were reported by 631 patients (6%) in the EAP, and 211 patients (2%) had related SAEs. c.  1.3 per 100,000 person years. d.Reporting rates do not represent the true incidence of SADRs as PM events tend to be underreported and are subject to various reporting biases. EAP (n = 10,343) (3,700 person years) PM Safety Database (455,392 person years) # of patients (%)Incidence Per 100,000 person years Reporting Rate Per 100,000 person years d Nausea110.12971.8 Rash10< 0.12701.8 Vomiting200.25411.3 Pneumonia660.61,7840.6 Weight Decrease5< 0.113522 SAEs from EAP a,b and Most Common SARDs from Post Marketing Safety Database c (Excluding SAEs listed in Specific SAE Categories of Interest and Serious Renal Adverse Event Categories) (cont’d)

11. Nelson M, et al. 13 th CROI, 2006; #781. Specific SAE Categories of Interest a CL/F (mL/min ) EAP (n = 10,343) (3,700 person years) PM Safety Database (455,392 person years) # of patients(%)Incidence per 100,000 person years Reporting Rate per 100,000 person years c Bone Abnormalities120.13241.1 Lactic Acidosis130.13514.2 Mitochondrial Toxicity1< 0.1271.5 Neuropathy6< 0.11620.7 Pancreatitis480.5 b 1,2975.5 a.Adverse events sometimes associated with ARV use. Each category includes multiple related SAE terms b.Incidence of pancreatitis was 0.7% in patients taking didanosine and 0.3% in patients not taking didanoise (p <0.001) c.See footnote d, SAEs from EAP a,b and Most Common SADRs from Post Marketing Safety Database c.

12. Nelson M, et al. 13 th CROI, 2006; #781. Serious Renal Adverse Event Categories a EAP (n = 10,343) (3,700 person years) PM Safety Database (455,392 person years) # of patients (%)Incidence per 100,000 person years Reporting Rate per 100,000 person years d Any Renal SAE b 560.51,51443.3 c Renal Failure320.386524.2 Renal Other110.12974.0 Serum Creatinine Inc. / Inc BUN 10< 0.12705.1 Fanconi / Tubular / Hypophos / Glyco 7< 0.118922.4 Nephrogenic DI1< 0.1272.2 Nephritis0002.4 Proteinuria0002.2 a.Each category includes multiple related SAE terms. b.Patients can have > 1 event. c.Reporting rate for non-serious renal events was 61.5 events per 100,000 person years. d.See footnote d, SAEs from EAP a,b and Most Common SADRs from Post Marketing Safety Database c.

13. Nelson M, et al. 13 th CROI, 2006; #781. Viread EAP: Abnormalities in Serum Creatinine a Patients with elevation in Serum Creatinine Baseline (n = 2,821)On Study (n = 1,699) Serum Creatinine Graden (%) Grade 1 (  0.5 mg/dL from BL) 0 (0)32 (1.9) Grade 2 (2.0 – 3.0 mg/dL)2 (0.1)5 (0.3) Grade 3 (3.1 – 6.0 mg/dL)0 (0)3 (0.2) Grade 4 (> 6.0 mg/dL)3 (0.1)2 (0.1) a.Patients in Viread EAP with available serum creatinine data.

14. Nelson M, et al. 13 th CROI, 2006; #781. Viread EAP: Risk Factors for Unconfirmed ≥ Grade 1 Serum Creatinine Increase – Multivariant Analysis Odds Ratio (95% CI)p-value Age1.05 (1.01, 1.09)0.021 Baseline CD4 – Ordinal Categories0.46 (0.30, 0.73)< 0.001 Baseline Weight0.94 (0.90, 0.97)< 0.001 Nephrotoxic Medications Taken at Baseline2.40 (1.08, 5.34)0.032 All patients with a baseline and followup serum creatinine, and relevant information on risk factors available (n = 911). Other risk factors evaluated in the model but did not reach significance were: – Abacavir taken at baseline, didanosine taken at baseline, LPV/r taken at baseline, lamivudine taken at baseline, stavudine taken at baseline, baseline creatinine, baseline HIV RNA - ordinal categories, CDC classification, coinfection with HBV, days since HIV diagnosis, diabetes at baseline, gender, hypertension at baseline, ACE inhibitors at baseline, and nephrotoxic antibiotics at baseline.

15. Nelson M, et al. 13 th CROI, 2006; #781. Viread EAP: Risk Factors for Unconfirmed ≥ Grade 2 Serum Creatinine Increase – Multivariant Analysis Odds Ratio (95% CI)p-value Baseline Creatinine17.4 (1.64, 184.1)< 0.018 Baseline Weight0.88 (0.82, 0.95)0.001 All patients with a baseline and followup serum creatinine, and relevant information on risk factors available (n = 911). Other risk factors evaluated in the model but did not reach significance were: –Abacavir taken at baseline, didanosine taken at baseline, LPV/r taken at baseline, lamivudine taken at baseline, stavudine taken at baseline, age, baseline CD4-ordinal categories, baseline HIV RNA ordinal categories, CDC classification, coinfection with HBV, days since HIV diagnosis, diabetes at baseline, gender, hypertension at baseline, nephrotoxic medications taken at baseline, ACE inhibitors at baseline, and nephrotoxic antibiotics at baseline.

16. Nelson M, et al. 13 th CROI, 2006; #781. Post Marketing Safety Database: For all post marketing renal events with creatinine data, the median maximum serum creatinine was 2.3 mg/dL (IQR 4.1). For post marketing serious renal events with creatinine data, the median maximum serum creatinine was 2.7 mg/dL (IQR 4.4).

17. Nelson M, et al. 13 th CROI, 2006; #781. Post Marketing Serious Renal Events – Time to Onset a Time to OnsetPercent of TotalPercent of Available Missing32 Available68 ≤ 30 days17 1 – 3 months11 > 3 to 6 months15 > 6 to 12 months17 > 1 to 12 months27 > 2 to 3 years11 > 3 to 4 years2 TOTAL100 a.All serious renal events with TDF start date and event onset data available. Reporting rate 29.2 events per 100,000 person-years. Median time to onset for all post marketing serious renal adverse events was 282 days (IQR 443 days).

18. Nelson M, et al. 13 th CROI, 2006; #781. Post Marketing Renal Events: Median Time to Resolution of Serum Creatinine a Days to Resolution (95% CI) Resolution to Grade 0 b (≤ 2.0 mg/dL) 86 (67 – 145) Resolution to ≤ Grade 1 c (≤ 2.0 mg/dL) 52 (29 – 95) Resolution to ≤ Grade 2 d (≤ 3.0 mg/dL) 29 (24 – 45) a.KM analysis of renal spontaneous reports with serum creatinine data available, time to resolution from TDF stop data. b.Includes maximum grades 1, 2, 3, and 4. c.Includes maximum grades, 2, 3, and 4. d.Includes maximum grades 3 and 4.

19. Nelson M, et al. 13 th CROI, 2006; #781. Possible Concomitant Risk Factors for Renal/Urinary Events Reported Between 1 November 2004 and 30 April 2005 a Concomitant Risk Factors for Renal Dysfunction b % of cases with medical history TOTAL Cases with information on medical history c 100% TOTAL Cases with one or more potential alternative cause of renal events84% Sepsis / Serious infection26% History of renal disease / baseline renal impairment24% Late stage HIV22% Concurrent nephrotoxic drug d 19% Hypertension16% Other e 16% Dehydration (e.g. due to vomiting / diarrhea)11% Diabetes9% Intercurrent lactic acidosis / pancreatitis / liver failure7% a.Spontaneous and serious, related clinical trial adverse event reports. b.Each case may involve more than one alternative cause. c.Reporting rate of 86 per 100,000 person years. d.Restricted to drugs well known for causing renal toxicity. e.Rhabdomyolysis, drug / alcohol abuse, liver disease, chemotherapy, hx low phosphate.

20. Nelson M, et al. 13 th CROI, 2006; #781. Conclusions The most common SAEs reported in the Viread EAP were pneumonia (0.6%), pancreatitis (0.5%), fever (0.4%), bacterial infection (0.3%), and lymphoma (0.3%). No individual SAE was reported in > 1% of patients. The incidence of all serious renal SAEs was 0.5% amongst 10,343 patients in the Viread EAP. The most common SADR categories reported in post-marketing safety surveillance were renal, pancreatitis, lactic acidosis, and fever. The pattern of renal events is similar in the post-marketing safety database and the Viread EAP database. Possible risk factors for renal events reported in the postmarketing safety database include concomitant nephrotoxic medications, late stage HIV, past history of renal disease, and sepsis. For all post marketing renal events with creatinine data, the median maximal serum creatinine was 2.3 mg/dL, and the median time to resolution to ≤ Grade 2 serum creatinine was 29 days.

21. Nelson M, et al. 13 th CROI, 2006; #781. Conclusions (cont’d) In multivariate analysis of data from Viread EAP, risk factors for increase in serum creatinine included low CD4 cell count, older age, low baseline weight, higher baseline serum creatinine, and concomitant nephrotoxic medications, but coadministration of Kaletra was not a risk factor. Bone fractures, neuropathy, and mitochondrial toxicity were reported infrequently in both the Viread EAP (≤ 0.1%) and in the postmarketing safety database. The safety profile of tenofovir DF observed in the Viread EAP confirms and extends the safety profile observed in the tenofovir DF clinical trials program. No new major unexpected toxicities have been observed in the post marketing safety surveillance program through 4 years observation.

22. Nelson M, et al. 13 th CROI, 2006; #781. Acknowledgments Gilead Sciences, Inc., would like to thank the large number of patients, physicians, and their research personnel who have participated in the Viread EAP and the CROs that assisted in the conduct of these studies: Parexel International; Ingenix Pharmaceutical Services, Inc.; and Charles River Labaratories. Additional members of the Viread Global Expanded Access Program include B Gazzard (UK), H Gallais (France), A Lazzarin (Italy), A Adam (Germany), B Clotet (Spain), R Colebunders (Belgium), J Lange (The Netherlands), MJ Aguas (Portugal), F Mulcahy (Ireland), S Follansbee (USA), J Elder (Charles River Laboratories), M Wulfsohn, L Metzler, A Cheng, and N Bischofberger (Gilead Sciences).