Ladies and gentlemen, thank you for standing by and welcome to the Gilead Sciences First Quarter 2008 Earnings Conference Call. At this time, all participants are in a listen-only mode. Later, we will conduct a question-and-answer session. As a reminder, this conference call is being recorded today, April 16, 2008. I will now like to turn the call over to Susan Hubbard, Vice President of Investor Relations. Please go ahead. Susan Hubbard - Investor Relations: Welcome to Gilead's first quarter 2008 earnings conference call. We're pleased, you could join us today. We issued a press release this afternoon, providing results for the first quarter ended March 31, 2008. This press release is also available on our website, at www.gilead.com. Joining me on today's call to discuss our results, are John Martin, President and Chief Executive Officer; John Milligan, Chief Operating Officer and Chief Financial Officer; Kevin Young, Executive Vice President of Commercial Operations; Norbert Bischofberger, Executive Vice President of Research and Development, and Chief Scientific Officer; and Matt Howe, Vice President of Finance. John Martin will take you through the corporate highlights through the quarter. John Milligan will review the first quarter 2008 financial results. Norbert Bischofberger will discuss our research and development programs, and Kevin Young will summarize our commercial milestones and provide more color on the market dynamics surrounding our various franchises. We will then allow time at the end of this call, to answer your questions. Before I turn the call over to John Martin for the corporate update, I would first like to remind you that we will be making statements relating to future events, expectations, trends, objectives and financial results that constitute forward-looking statements, within the meaning of the Private Securities Act of 1995. These statements are based on certain assumptions and are subject to a number of risks and uncertainties that could cause our actual results to differ materially from those expressed in any forward-looking statements. I refer to you our Form 10-K for the year ended December 31, 2007, subsequent press releases and other publicly filed SEC disclosure documents, for a detailed description of the risk factors affecting our business. In addition, please note that we undertake no obligation to update or revise these forward-looking statements. We will also be making certain references to financial measures that are on a non-GAAP basis. We provide a reconciliation between GAAP and non-GAAP numbers on our website. I will now turn the call over to John Martin. John C. Martin, PhD - President and Chief Executive Officer: Thank you Susan. Good afternoon everyone and thank you for joining us today. We are pleased to summarize for you, Gilead's accomplishments during the first quarter of 2008. I will start by reviewing our corporate milestones for the quarter and our thoughts on some emerging data that may affect the HIV treatment landscape. And then turn the call over to John Milligan, who will run through the financial results for the quarter. First, in February, our partner GlaxoSmithKline, announced that ambrisentan, with a trade name of Volibris in Europe, has received a positive opinion from the European Committee for Medicinal Products for Human Use, for the treatment of pulmonary arterial hypertension in patients classified as World Health Organizational Functional Class II and III, to improve the exercise capacity. GSK has stated that it expects approval by the European Commission in the coming weeks. Also we announced in March that we entered into an agreement with Goldman Sachs & Company to repurchase $500 million of common stock, under an accelerated share repurchase program. We also appointed Jay Toole to the position of Senior Vice President, Corporate Development. As many of you know, Jay is a PhD scientist and physician, who joined Gilead in 1990 and has played a leadership role in many of our key discovery and clinical research programs. Now, I would like to take a few minutes to talk about the evolving HIV landscape. First, providing a brief background on two important data sets on GSK's abacavir, that emerged during the first quarter, mainly the DAD, the ACTG 5202 study results. The DAD data were presented at the Conference on Retroviruses and Opportunistic Infections in February of this year and were subsequently published in The Lancet in April. The data collection on adverse events of anti-HIV drugs or DAD, is the name of a study that includes 11 cohorts of more than 33,000 HIV-infected patients in 21 countries, including many in Europe, Australia and the United States. It was established to follow HIV patients over the long term, to assess cardiovascular-related morbidity and mortality outcomes. The data showed that the use of abacavir is associated with a 90%, almost two-fold increase in the risk of myocardial infarction or MI. The second, ACTG 5202 is a U.S-based study, conducted by the AIDS Clinical Trial Group and sponsored by NIAID, comparing in part Truvada and Epzicom head-to-head. The study which commenced in late 2006, enrolled 1800 treatment-naïve patients who were randomized to receive one of four regimens, Truvada or Epzicom with either Sustiva or ambrisentan Letairis [ph]. The Data and Safety Monitoring Board of the Division Of AIDS met in early February and reviewed preliminary study data. The review indicated that Epzicom patients who had screening, have high viral loads of more than 100,000 copies, experienced significantly higher rates of biologic failure, and grade three and four adverse events. These data led the ACTG to recommend to investigators that patients with high viral loads of screening, nearly half of all patients be unblinded and counseled on what the DSMB findings could mean to them, and consider switching of a regimen containing Epzicom. The study is continuing in this modified fashion. I'm certain that there will be continued discussion about the importance and potential impact of these two data sets. But at this point, we believe it would be premature and inappropriate for us to speculate on any potential regulatory actions, either in the U.S or European Union, resulting from the study results. Gilead remains focused on our continue efforts to ensure physicians understand the profile of Truvada either as part of Atripla, or in combination with the protease inhibitor. I would like to make a brief update on the further progress made during the quarter to increase the diagnosis and treatment of HIV in the U.S, specifically in Virginia, the State House of Delegates passed and the Governor signed a bill, eliminating written informed consent and pretest counseling requirements inline with the CDC recommendations. This brings the number of states that have taken legislative steps to reduce the barriers to testing and guidelines to nine. Additionally, similar bills have been introduced in Maryland, Massachusetts and Nebraska. Before I turn the call over to John Milligan, I would like to say from my perspective, Gilead has never been stronger with more opportunities than ever before to continue to grow our existing marketed products, including the further roll out of Atripla throughout Europe, the anticipated introduction of aztreonam lysine for inhalation for cystic fibrosis, and Viread for HPV into market and the significant progress that we are making with our research and development programs. And with Jay Toole taking the lead in our business development activities, we will continue to look at products and programs that complement our existing business units. I am very proud of the more than the 3000 employees here at Gilead, and the efforts they make everyday to improve the lives of patients suffering from life-threatening diseases worldwide. Now to our financials. John? John F. Milligan, PhD - Chief Operating Officer and Chief Financial Officer: Thank you, John. The first quarter of 2008 was another very successful quarter. Total revenues, which include products sales and royalty, contract and other revenue for the first quarter of 2008 were $1.3 billion. First quarter product sales were $1.1 billion, a 30% increase compared to the first quarter of 2007 and our second consecutive quarter surpassing $1 billion in product sale. HIV product sales totaled $965 million for the first quarter of 2008, driven primarily by the continued strong uptake of Atripla in the United States, as well as the strong growth of Truvada in United States and Europe. Operating expenses were $350 million, an 18% increase over the first quarter of the prior year. This reflects our commitment to investing in our pipeline and our geographic expansion, while keeping the sharp focus on overall expense management. As we have noted in the past, we plan to continue to expand our operations in Europe and Kevin will speak to you in a few minutes, about the progress we are making in this regard. Our first quarter 2008 net income was $496 million or $0.51 per share on a fully diluted basis. Non-GAAP net income per share for the first quarter of 2008, excluding the impact of after-tax stock-based compensation expense was $0.54 per share on a fully diluted basis, a 16% increase over the first quarter of 2007 non-GAAP diluted net income per share of $0.46 per share, which also excluded the impact of after-tax stock-based compensation expenses. During the first quarter of 2008, we generated $557 million in operating cash flow and repurchased retired 16.5 million shares of our common stock at a cost of $816 million. Now turning to the specific results for the first quarter. Total revenues for the first quarter of 2008 were $1.3 billion, an increase of 22% from total revenue of $1.0 billion in the first quarter of 2007. This performance is driven by a $301 million increase in our product sales, partially offset by a $71 million decrease in our royalty contract and other revenues, compared to the first quarter of 2007. Product sales were a record $1.1 billion for the first quarter of 2008, marking four consecutive years of quarterly product sales growth. Product sales from the first quarter increased sequentially by 11%, as our HIV product sales continues to grow. In terms of the foreign exchange impact, $37 million of our product sales increase in the first quarter of 2008 was due to the favorable foreign currency exchange, when compared to the same period in 2007 and $9 million when compared to the fourth quarter of 2007. This favorable impact takes into account our hedging activities. Royalty, contracts, and other revenues increased from the fourth quarter of 2007 by 70%, due primarily to the increase in Tamiflu royalties. Now turning to more specifics on product sales. HIV product sales grew to $965 million for the first quarter of 2008, up 37% from $705 million in the first quarter of 2007 and up 12% sequentially from the fourth quarter of 2007. Atripla contributed $324 million to our first quarter HIV product sales, as demand for this product continue to increase in the U.S. Atripla sales accounted for 34% of our total HIV franchise sales in the first quarter of 2008. Efavirenz portion of Atripla, which is distributed back to BMS and reflected in the cost of goods sold line, was approximately $120 million or about 37% of Atripla sales in the first quarter of 2008. In addition to growth in retail demand, we also observed large non-retail purchases in the fourth quarter of 2008 via small number of essentially purchasing state AID Effort Council's [ph] warehousing capability. We believe such purchases could be driven by the grant cycles of federal AID out funds rather than being completely demand driven. And therefore contemporary orders in the current quarter, given the likely increase in inventory levels in those accounts exiting the first quarter. Truvada sales were $479 million for the first quarter of 2008, up 39% compared to the first quarter of 2007, of which approximately 6% was driven by the favorable foreign currency exchange impact when compared to the first quarter of 2007. Truvada sales for the first quarter of 2008, were up 7% sequentially from the fourth quarter of 2007, of which approximately 1% was driven by the favorable foreign currency exchange impact when compared to the fourth quarter of 2007. Truvada sales accounted for approximately half of our total HIV franchise sales in the first quarter of 2008. In the U.S, Truvada sales were $239 million for the first quarter of 2008, up 28% compared to the first quarter of 2007. Sequentially, U.S sales were up 14%, demonstrating Truvada's continued update as the NRTI backbone of choice when used in combination with protease inhibitors. The growth of Truvada sales was also driven by our January 2008 price increase in the U.S, as well as the higher than usual non-retail purchases state AID efforts councils, as I described earlier. In Europe Truvada sales for the first quarter of 2008 were $218 million, an increase of 50% compared to the first quarter of 2007, driven by strong sales volume growth and a favorable foreign exchange environment. Sequentially, Truvada sales in Europe increased 3%, mostly driven by the favorable foreign exchange. As we discussed in our year-end earnings call, in response to an increased level of parallel trade activity in the region, effective December 1, 2007, the company initiated supply management system in France to manage orders of Truvada and Viread to ensure adequate and appropriate supplies of those products, commensurate with the market demand in France. Based on the results today, we currently believe that the supply management system has accomplished what we had hoped and we expect that future sales in the region will better approximate demand. We will continue to monitor parallel trade activity to ensure continued effectiveness of our supply management system. Viread sales were a $153 million for the first quarter of 2008, down 5% in the same period in 2007, due primarily to lower sales volumes in the U.S and Europe, partially offset by a favorable foreign currency exchange impact. Viread sales for the first quarter of 2008, increased 3% compared to the fourth quarter of 2007, primarily due to favorable foreign currency exchange environment and higher pricing. Hepsera, for the treatment of chronic Hepatitis B, generated sales of $83 million in the first quarter of 2008, up 16% compared to the first quarter of 2007, of which approximately 7% was driven by the favorable foreign currency exchange impact. Hepsera sales for the first quarter of 2008 experienced an 8% increase sequentially, driven primarily by sales volume growth in the U.S and certain European markets. Sales of AmBisome were $71 million for the first quarter of 2008, an increase of 15% when compared to the first quarter of 2007, of which approximately 8% was driven by the driven favorable foreign currency exchange environment. AmBisome sales increased by 5% sequentially, due to primarily the increased sales volumes in certain European and international regions. Finally, Letairis sales were $20 million for the first quarter of 2008. Letairis is approved by the FDA for the treatment of pulmonary arterial hypertension in the United States in June 2007. We are very pleased with its ramp since launch. Our royalty contract and other revenues for the first quarter 2008, decreased by 38% compared to the same quarter of 2007 and increased by 70% over the fourth quarter of 2007, due primarily to the royalty revenues from Tamiflu sales made by Roche. The changes in Tamiflu sales in both comparative periods were due primarily to the fluctuations in sales related to the government pandemic planning initiatives worldwide. Royalties received from Roche and recognized in our revenues for the first quarter of 2008 were $93 million. These royalties, which are paid one quarter every year [ph], reflect a royalty rate of approximately of 22% as applied to Roche's sales of Tamiflu in the first quarter of 2007. As you may be aware, Roche's scheduled to report first quarter 2008 earnings tomorrow. Now turning to product gross margin. Non-GAAP product gross margin for the first quarter of 2008, which excludes stock-based compensation expense was approximately 79.1% compared to non-GAAP product gross margin of approximately 79.9% for the same quarter of 2007, was only 9.3% for the fourth quarter 2007. The lower product gross margin when compared to the same period of last year was primarily due to the higher proportion of Atripla sales, which carries efavirenz portion at zero gross margin, partially offset by a favorable overall product mix. Turning to expenses; non-GAAP R&D expenses, which excludes stock-based compensation expense for the first quarter 2008 were $138 million. This is an increase of 27%, from $109 million in the same period of last year, primarily as a result of increased clinical study expenses as well as higher head count related to the growth in our business. Compared to the fourth quarter of 2007, non-GAAP R&D expenses for the first quarter of 2008 decreased 18% from a $169 million, primarily driven by the higher license payments to Gilead's collaboration partners in fourth quarter of 2007 and partially offset by the increase of clinical study expenses in the first quarter of 2008, as well as higher head count. Non-GAAP SG&A expenses which excludes stock-based compensation expense for the first quarter of 2008 were $177 million, an increase of 33% compared to $133 million in the same period of last year due primarily to increased marketing, promotional and other expenses in support of our antiviral and cardiovascular programs as well as higher head count, especially in our cardiovascular business. The stronger yield also contributed to higher expenses in U.S dollar returns for our Euro-based operations. On a sequential basis, non-GAAP SG&A expenses for the first quarter of 2008 increased by 7% from $165 million in the fourth quarter of 2007, due primarily to higher head count and other expenses to support the growth in our business. In our first quarter 2008 revenues and pretax earnings, foreign currency exchange had a net favorable impact of $37 million and $20 million respectively, when compared to the same period of last year. When compared to the fourth quarter of 2007, the foreign currency exchange impact on our first quarter 2008 revenues was favorable by $9 million or the impact on our first quarter 2008 pretax earnings was not significant. These take into account the products sales and expenses generated from outside the United States, as well as our hedging activities. Our effective tax rate for the first quarter of 2008 was 28.0%. Our effective tax rate for the full year of 2007 was 28.9%. The lower effective tax rate in the first quarter of 2008 compared to full year 2007, was primarily driven by increased earnings in favorable tax jurisdictions. Next, I would like to turn to our operating cash flow performance for the quarter and finally, our net cash position at the end of the first quarter. In the first quarter of 2008, we generated $577 million in operating cash flow. Our balance sheet at March 31, 2008 shows cash, cash equivalents and marketable securities of $2.6 billion, a decrease of $133 million when compared to the balance of approximately $2.7 billion, at December 31, 2007. We also repurchased 16.5 million shares of our common stock at a cost of $816 million this quarter, under our $3 billion share repurchase program. This includes a $500 million of common stock that we repurchased on the accelerated share repurchase agreement that we entered into in March, with Goldman Sachs & Co. As of March 31, 2008, we had approximately $2.2 billion remaining under this share repurchase program, which will expire at the end of 2010. We continue to actively evaluate strategic ways to use our cash and investments, including continuing our efforts to pursue opportunities to in-license or acquire products to complement our own internal efforts. We are also committed to returning cash to our stockholders as is evidenced by the ongoing share repurchase program. Now, I would like to turn to our financial guidance for the full year 2008. You can locate all of our guidance for the 2008 year on Gilead's corporate website. The only metric that we will be updating for our guidance we provided to you in January is the effective tax rate for the full year 2008, which we now expect to be in the range of 28% to 29% compared to our previous guidance of 29% to 30%. The decrease in effective tax rate guidance is primarily related to increased revenues in favorable tax jurisdictions. For all other metrics we are reiterating our previous guidance. We are very pleased with a sequential quarter-over-quarter growth in our product revenues, particularly HIV franchise. As I discussed previously however, we saw larger than usual purchases of our HIV products by a small number of U.S. states which we believe may be related to their ADAD budgetary cycle, which could result in significant lower orders in the second quarter based on their current estimated inventory levels. In addition, the exact timing of anticipated pricing approvals and subsequent launches of Atripla in European countries is still uncertain, and will have an impact on our product revenues. And finally, foreign exchange rates remain extremely volatile due to macroeconomic factors and it's difficult to predict at this point, whether current rates are sustainable, and how future fluctuations in these foreign exchange rates could affect our revenues and expenses for the remainder of the year. Therefore, I am reiterating the guidance of $4.7 billion to $4.8 billion in the net product revenues for 2008. This is for direct product builds only and does not include royalty contracts or other revenues. As a remainder, expense guidance we are reiterating today will be non-GAAP, which excludes the impact of stock-based compensation expense. We are reiterating our full year non-GAAP gross margin guidance in the range of 77% to 79%. We are also reiterating our full year expense guidance of $610 million to $630 million for the non-GAAP R&D expenses, and $710 million to $730 million for non-GAAP SG&A expenses. And finally, regarding after-tax stock-based compensation expense, we are reiterating the 2008 fully diluted EPS impact to be in the range of $0.12 to $0.14 per share. In conclusion, our solid operating performance continues to be a validation of the significant efforts made by the more than 3000 Gilead employees, remain committed to driving performance to our shareholders by working to improve the lives of patients around the world. At this point, I'd like to turn the call over the Norbert, who will discus or research and development highlights for the quarter. Norbert? Norbert W. Bischofberger, PhD - Executive Vice President, Research and Development and Chief Scientific Officer: Thank you John. In the first quarter of this year, Gilead achieved several significant research and development milestones, further advancing our pipeline programs. As you know, we now a more robust pipeline of product candidates than ever before. So I'm going only to focus on those that have made significant advancements during the quarter. On the antiviral front starting with HIV, I am very pleased to provide you an update on our elvitegravir program. First, with FDA's consent we are nearing completion of the design of the Phase III program for elvitegravir. As we have previously communicated, we will be conducting two non-inferiority studies evaluating elvitegravir versus Merck's ratelgravir [ph]. Because of the clean safety profile of the highest dose of elvitegravir study in the Phase II trial, the FDA requested that we consider evaluating two doses of elvitegravir in the Phase III studies, a 150 and a higher dose 300 milligrams with the thought that the 300 milligram dose could provide greater efficacy for patients with more advanced disease. Based on recently obtained PK data demonstrating that the 300 milligram dose does not provide substantially higher exposure than the 150 milligram dose, we will no longer be required to evaluate the 300 milligram dose and the planned Phase III studies will only have two arms. The two studies will enroll patients in the U.S. and in Europe and the primary endpoint will be the proportion of patients that achieve and maintain HIV RNA less than 50 copies per mill at week 48. Due to the work we did to revolve the need to evaluate the 300 milligram dose, we now anticipate initiating these studies in the third quarter of this year. I am also very pleased for the first time to provide you with the details on our PK enhancer program. As you know elvitegravir requires that it be boosted with 100 milligrams ritonavir in order to be dosed once a day. Because of the benefit of simplified and convenient therapies to patients as exemplified by our own Atripla, it is our goal to also coformulate elvitegravir into a one pill, once daily complete regimen. The incorporation of ritonavir, however, presents a challenge, because of the requirement for specialized formulation. Though our strategy has been to develop a proprietary boosting agent, one which is devoid of HIV activity, can easily be manufactured and can be given at relatively low dose so that coformulation with elvitegravir and dose of Truvada is a possibility. We now have that candidate with GS-9350, which appears to fit all of these criteria. In fact, a pilot formulation study demonstrated that we can coformulate 9350 with elvitegravir and Truvada into one single pill. We have filed the IND and we are currently preparing to evaluate the safety, tolerability, and metabolic profile of GS-9350 in healthy volunteers. If the results are positive, we could then move the compound into HIV infected individuals, evaluating safety and efficacy as a boosting agent versus ritonavir. We look forward to keeping you posted on the progress we make with this compound. On the HCV front following submission of data to FDA, we have now resumed screening patients in the continuation of the Phase Ib Study of GS-9190, our novel HCV polymerase inhibitor. We will continue the evaluation of the 40 milligram dose, which based on a pilot QTC study in healthy volunteers, appear to have QTcF prolongations that were small and clinically manageable. We will now finish enrolling patients in the Phase Ib study to establish the safety and efficacy of the 40 milligram dose in a sufficient number of patients to allow us to go forward into Phase II studies. With regards to 9450, our caspase inhibitor in-licensed last year, the compound is currently being evaluated as a hepatoprotectant in an ongoing Phase Ia study in HCV infected individuals. We have recently added U.S. sites to this study which will accelerate the enrollment of patients, and we anticipate data from this trial by the end of the year. We believe that this molecule may also have utility in other diseases such as fatty liver disease or NASH. On the respiratory front, aztreonam lysine for inhalation was Gilead's unique drug formulation specifically designed to achieve high lung antibiotic concentrations with a short duration of administration. The U.S. NDA was filed on November 16, 2007 and we had PDUFA date of September 16 of this year. In order to make the product available to CF patients in need prior to its commercial availability, we opened up an expanded access program and now have more than 100 patients enrolled in the program. Ahead of schedule, we announced that we filed a marketing authorization application in the European Union on March 7, and we have since also filed in Canada where the submission was granted a priority review. We are preparing to conduct a head-to-head open label study versus TOBI in the EU to support registration and plan to initiate the study shortly. The study will not need to be completed in... completed in order to get an approval in the EU but it will support a conditional approval strategy. We will also be initiating in the second quarter of 2008 a study called the mild study that will evaluate the quality of life of aztreonam lysine for inhalation in patients whose lung function is risk less compromised than patient who were enrolled in our Phase III pivotal studies. Quality of life will be accessed by CFQ-R, a patient's reported outcome tool used to measure health-related quality of life for people with CF. If the outcome from this study is positive, aztreonam lysine would be the only inhaled antibiotic with demonstrated benefit in earlier diseased CF patients with pseudomonas infections. With regards to our cardiovascular franchise, the Phase III studies for darusentan and resistant hypertensions, our progress in terms of enrollment in both the DAR-311 and DAR-312 studies which were approximately 58% and 25% enrolled respectively. The darusentan data monitoring committee met recently and recommended that the studies be continued. We believe we are on track to complete enrollment and receive data from these studies in 2009. I am very pleased with the progress Gilead has made in the first quarter and look forward to informing you on further advancements of our pipeline candidates through the remainder of this year. With that... next, Kevin will review our commercial highlights for the quarter. Kevin? Kevin Young - Executive Vice President, Commercial Operations: Thank you, Norbert and good afternoon everyone. The first quarter of 2008 was an extraordinary quarter with multiple significant events occurring. I am referring to the results from the DAD data and the AC... ACTG 5202 study which John Martin previously discussed. The treatment communities' ongoing discussion and decisions around the potential impact of these data sets along with our anticipated new product launches will continue to make 2008 a very exciting year. However, we believe this data did not have any impact on product revenues for the first quarter. Before turning to our commercial performance for the quarter, I would like to remind you that the analysis of our HIV and HBV market share data in the U.S. and Europe, we rely on the most up-to-date third party data available to us in each market. This data lags our financial results by one quarter. I would first like to discuss the performance of our antiviral franchise which is comprised of our HIV and HBV marketed products. Our U.S. HIV franchise performance remained the best in the industry in Q4 of 2007, and the gap between Gilead and our closet competitors continued to widen. Atripla, built on its leadership position in the U.S., has approximately 28% of the estimated 538,000 patients treated with antiretrovirals or just over 150,000 patients were on Atripla therapy. Atripla, together with Truvada, when prescribed as an alternative therapy with protease inhibitors, continue to account for approximately 8 out of 10 treatment-naïve patients. In patients switching to Atripla from other therapies, over 50% were from non- Gilead-based regimens. Patients previously on Combivir continue to dominate switch patients compromising... comprising 29% of the total patients who switch to Atripla. Truvada continued to be the backbone of choice for antiviral therapy in the U.S. with an estimated 169,000 patients receiving Truvada. This represented an impressive 31% of all patients treated with antiretrovirals. Notably 68% of all U.S. patients or 365,000 received the tenofovir molecule during the fourth quarter of 2007 in one of its three forms, namely Atripla, Truvada or Viread, an increase from 64% from the third quarter of 2007. We continue to make excellent progress with our HIV products in Europe and believe that with the continued rollout of Atripla as well as further responses to the DAD data and the ACTG 5202 study, we will continue to build upon our strong position. As you know, we and our partner Bristol Myers-Squibb received European approval for Atripla in late December 2007. The launch is well underway in the UK, Germany and Austria. And just last week, I'm pleased to announce that we launched in Greece. In addition, pricing negotiations are progressing well with France, Italy, Portugal and Spain. And we believe we are on track to have those finalized before the end of the third quarter, with other European Union countries rolling out over the course of the year. The market opportunity in the big five countries continued to show robust growth, and it was estimated that as of the fourth quarter 2007, 256,000 patients were treated with antiretrovirals within these five markets. This represents a 9% year-over-year growth rate and is comparable to the rate of growth achieved in the U.S. Truvada has continued to build on a strong base throughout the EU and was the number one brand throughout the big five markets, while tenofovir was the leading molecule in France, Spain, Germany and the UK during the same period. We anticipate that we will achieve the same position in Italy, during the current quarter. Truvada plus Sustiva continued to extend their lead as the combination of choice for treatment of naïve patients, growing to 27% of treatment naïve patients, which is more than double the next closest regimen of Truvada plus Kaletra up 13%. An important potential driver to solidifying this regimen's first line position is that the British HIV Association was the first committee to react to the DAD data and the ACTG study, by recently publishing revised UK HIV treatment guidelines for consultation. If these guidelines are finalized at the end of the consultation period, on May, the 16th and remain unchanged, Truvada plus Sustiva will become the preferred regimen for patients in frontline use in the UK. Of all treatment initiations on to Truvada during the fourth quarter of 2007, 60% came from treatment naïve patients, whilst 40% have switched from other products. Of the patients that switched to Truvada, approximately half have been on a Combivir base regimen In the NRTI market, Truvada continued to outperform Kivexa, known in the U.S as Epzicom with a Truvada, versus Kivexa market share ratio of 2.3:1. This will be an important metric for us to watch, as we monitor the impact of the launch of Atripla, as well as the response to the DAD data and ACTG 5202 study. And finally on the HIV front, approximately 55% of all patients for initiated therapy began on a regimen that contains Truvada. Turning briefly to our hepatitis franchise. During the first quarter of 2008, in the United States Hepsera continued to be the leading antiviral agent for the treatment of chronic hepatitis B. As of the end of February 2008, Hepsera maintained its place as market leader, with a total prescription market share of approximately 44%. In the Gilead territories outside the U.S, Hepsera's market share remained relatively stable, despite strong competition. Turning to Viread for HPV; in late March, we were very pleased to have received our first approval of Viread for this indication in Turkey and we are currently awaiting reimbursement authorization prior to launching the product. With an estimated 350,000 chronically infected HPV patients, Turkey represents an important market and is a country in which we have established a direct Gilead presence. Also in March, the Committee for Medicinal Products for Human Use of the European Medicines Agency issued a positive opinion on the approval of Viread for HPV throughout the EU. And we currently anticipate approval in the second quarter. As we prepare for the anticipated European approval of Viread for HPV this quarter, we are excited about the timing of the European Association for the Study of the Liver Conference taking place next week in Milan, Italy. This event will pull together key thought leaders in HPV from throughout Europe and will allow us to showcase the attributes of our HPV portfolio, particularly Viread for HPV. There will be presentations from 10 Gilead sponsored abstracts, five of which are oral presentations. In reviewing our commercial readiness to support a successful launch of Viread for HPV in the EU, as well as potentially the U.S later this year, we are far along in our pre-launch preparations. And feel we are well positioned to support a successful rollout with our existing commercial infrastructure in both of these markets. Now turning to our cardiovascular franchise; and Letairis for the treatment of pulmonary arterial hypertension or PAH. In an effort to share additional details on the Letairis launch on the PAH market, we conducted a survey of approximately 100 prescribing physicians responsible for more than 10,000 PAH patients in late March of this year. We are in the process of refining a robust dataset in cooperation with a third party source that we hope to use in coming quarters. Until such time that we feel that data is reliable and indicative of market trends, we will continue to conduct our own market research for use on our earnings calls. We are very pleased with the recent performance of Letairis as well as the market dynamics, we have been seeing. During the first quarter, we have recorded $20 million of Letairis sales, which very much in line with our expectations at this point in the launch. We now have approximately 3600 physicians enrolled in our Letairis Education and Access Program, otherwise known as LEAP. Of these physicians, approximately 25% represent the main treatment providers for PAH. The remaining 75% are an important part of the referral base and their continued education is essential to our efforts to expand awareness and diagnosis of this disease. Letairis has an approximate 15% share of ERA-treated PAH patients, as of our March Gilead conducted survey. Importantly, in the PAH centers, which accounted for approximately 60% of all the Letairis patients, that share was approximately 20%. Letairis captured approximately 24% of newly diagnosed patients treated with an ERA during this period, according to our survey data Since the launch of Letairis, patients have come from three primary sources. Patients new to therapy, patients who have switched to Letairis from other PAH treatments, namely the sentan and PDE5 inhibitors and finally patients, who have had Letairis added to their existing therapy. Monotherapy currently comprises of approximately 60% of PAH-treated patients, with the use of combination therapy at approximately 40%. On the reimbursement front, access barriers have been minimal and manageable since the launch of Letairis, with comparable coverage to the sentan on most formal risk. Letairis is covered on virtually all of the top managed care plans as well as on virtually all state Medicaid plans. We are very encouraged with the physicians' feedback we've been receiving. As their experience grows, physicians are gaining additional comfort in expanding the number of patients to whom they prescribe Letairis. We believe, we are well positioned to build upon the early success of Letairis. And to further support the product, we'll be initiating our Athena 1 Phase IV program shortly. In this study, we will evaluate Letairis in patients who are poor responders to sildenafil monotherapy. Importantly, at the upcoming American Thoracic Society Meeting taking place in Toronto, on May of the 16th through May of the 21st, we will update different four studies of Gilead products, two for Letairis, one from our ARIES-E study and one from our ARIES 1 study. We will also have a poster presentation on aztreonam lysine for inhalation from the interim data from the open-label study, and one poster from our Phase I study in CF Patients of GS 9310, 9311, of phosphomycin, tobramycin antibiotic combination therapy. As Norbert mentioned earlier, we have a producer date of September, the 16th for aztreonam lysine with the FDA, and have already begun our launch preparedness. We believe, we are in excellent position to launch this product, without major additions to our existing sales force. In closing, I am pleased with the commercial progress we have made in the first quarter, and believe we have led a strong foundation for growth, of the remainder of 2008 and into 2009. I will now turn the call over to the operator to begin the question-and-answer portion of the call. Operator? Question And Answer