Biogen's ( BGEN) shares were trading down after the biotech company reiterated its full-year earnings and sales guidance but said that royalty revenue for 2003 could be at the low end of its estimated range. The company still expects 2003 revenue growth in the mid-teens and earnings of $1.72 to $1.85. Though royalty revenue will probably come in at the low side of the $145 million to $160 million range projected in April, Biogen said sales of the multiple sclerosis drug Avonex will be an offsetting factor. Biogen gets royalties on sales of Intron A, a hepatitis treatment marketed by Schering-Plough ( SGP). In May, Schering-Plough said Intron sales fell in the first quarter, mainly because of reductions in trade inventory levels. On average, analysts polled by Thomson First Call expect Biogen to earn $1.78 this year, with sales of $1.3 billion. Separately, Biogen and Icos ( ICOS) ended their collaboration on a prospective treatment for inflammations after determining that one of the compounds being studied didn't warrant additional trials. As a result of terminating the pact, Icos will see second-quarter revenue of about $21 million, equating to 34 cents a share, from upfront fees and forgiven loans that have previously been recorded as deferred revenue. Icos also said it has signed a biologics manufacturing agreement with Eli Lilly ( LLY). Shares of Biogen were dropping $1.44, or 3%, to $47.70 in recent Nasdaq trading. Icos was gaining $2.12 to $41.02. The Amex Biotech Index was posting a slim gain, and the Nasdaq Biotech Index was slightly lower.