MATTHEW PERRONE AP Business Writer WASHINGTON (AP) — The Food and Drug Administration said Tuesday an HIV drug from Pfizer appears safe for expanded use in patients who have not already taken other drugs to combat the virus. However, the FDA said Pfizer studies paint a mixed picture of its drug's effectiveness. A 48-week study comparing Selzentry to Bristol-Myers Squibb's Sustiva failed to meet the goal of showing Pfizer's drug was at least as effective at suppressing HIV. When Pfizer reanalyzed the results using a different test to screen patients, the study met its goal. Selzentry is currently approved as a secondary option for HIV patients who are not responding to other antiviral drugs. The company is asking the FDA to approve the drug as a first-choice treatment. FDA scientists appeared to favor the new use in briefing documents posted online Tuesday. The review noted "no new safety signals were identified in association" with the drug. Selzentry carries a boxed warning about potential liver toxicity, but FDA reviewers said reports of such events were low in company trials. On Thursday, the FDA will ask a panel of outside viral experts to vote on whether the drug appears safe and effective. The agency usually follows the group's advice, though it is not required to. Selzentry is part of a recently developed class of treatments that block HIV from entering white blood cells through a pathway present in some patients. While more than 1 million people in the U.S. are HIV positive, only a subset of that group respond to Pfizer's pill. The drug works by blocking the so-called CCR5 receptor. Selzentry had sales of $46 million last year, according to Pfizer. In briefing documents posted online, the New York-based company said "there is a continuing medical need for a range of safe and well tolerated" anti-HIV drugs. HIV attacks the body's immune system, eventually causing AIDS.