BETHESDA, Md. ( TheStreet) -- Human Genome Sciences ( HGSI) shares dropped Wednesday as investor concerns shifted from approval of its lupus drug Benlysta to the potential for a narrower-than-expected label and a slow commercial launch. Two downgrades Wednesday morning, one each from Citi and Bank of America/Merrill Lynch, reflected these new concerns and sent Human Genome shares down 7% to $23.98 in early trading. An advisory panel convened by the U.S. Food and Drug Administration voted 13-2 Tuesday night to recommend Benlysta's approval as the first new lupus therapy in 50 years. The large margin of victory represented in the vote count, however, belied the contentiousness of the panel's discussion over Benlysta's efficacy. Many of the panelists expressed concern that Benlysta provided only a marginal benefit for U.S. lupus patients and that some specific types of lupus patients -- African Americans or those with lupus that attacks the kidneys or the central nervous system -- were not helped by the drug at all. Despite recommending Benlysta's approval, the FDA panel expressed support for a label that potentially restricts the drug's use to a smaller segment of U.S. lupus patients than Wall Street had expected. "The label will likely have noticeable restrictions and thin efficacy is already drawing a mixed reception from rheumatologists. We are concerned about the long-term sales potential given (1) modest benefit, (2) poorer activity in U.S. pts than we originally expected, and (3) now more restricted label," wrote Citi biotech analyst Yaron Werber in note Wednesday in which he downgraded Human Genome to a hold from a buy. Werber cut his peak sales estimate for Benlysta to $1.6 billion from $2.6 billion and as a result his Human Genome price target dropped to $30 from $35. Similarly, Bank of America/Merrill Lynch downgraded Human Genome to underperform with a $24 price target. Investors are also concerned that FDA and Human Genome may not be able to resolve the outstanding issues needed to complete the Benlysta review in time to meet the Dec. 9 approval decision date. This increases the likelihood that Benlysta's approval could be delayed 1-3 months.