InterMune Inc. said late Wednesday that it saw positive top-line results in its confirmatory Phase III trial of oritavancin in complicated skin/skin-structure infections caused by Gram-positive bacteria. It also gave guidance for its second-quarter sales and dropped its full-year estimates.

It was the latter bit of news that investors considered more, dropping InterMune's stock (NASDAQ:ITMN) $8.36 Thursday, or 33.3 percent, to close at $16.74.

Actimmune (interferon gamma-1b) is approved in the U.S. for chronic granulomatous disease and severe, malignant osteopetrosis. The company said it is expecting between $30 million and $33 million in Actimmune sales for the period ending June 30, and therefore lowered its year-end guidance from the $160 million to $180 million range to $135 million to $150 million.

It also lowered its total-revenue, full-year estimate, dropping it from $170 million to $195 million down to $145 million to $165 million. The company also dropped its previous estimate of about 3,300 patients being on Actimmune therapy as of the end of the first quarter to about 2,900. Sales of Actimmune in the first quarter were $37.9 million, compared to $17.7 million in the same period in 2002.

Scott Harkonen, CEO and president of Brisbane, Calif.-based InterMune, noted that $37.9 million first-quarter figure, using it as a basis to say in a prepared statement, "With positive data presented at [the American Thoracic Society] and growing physician awareness about the diagnosis of idiopathic pulmonary fibrosis, we remain optimistic about the future of interferon gamma-1b."

The presentation at the thoracic meeting focused on Actimmune in patients with idiopathic pulmonary fibrosis (IPF). The company reviewed a final primary data analysis from InterMune's Phase III trial evaluating interferon gamma-1b in patients with IPF, as well as exploratory analyses from a follow-up observation period and additional follow-up survival data in which a survival benefit continued to be observed in patients initially randomized to receive treatment with interferon gamma-1b (30 percent relative reduction in risk of death; p = 0.07). While a survival benefit was seen in the trial's primary analysis, it was less than anticipated, which sent InterMune's stock down nearly 20 percent in January. (See BioWorld Today, Jan. 8, 2003.)

The good news for Actimmune was the oritavancin data. The positive top-line results from the confirmatory Phase III trial in complicated skin/skin-structure infections caused by Gram-positive bacteria showed the drug achieved its primary efficacy endpoint, demonstrating that oritavancin was as effective as the comparator regimen of vancomycin followed by cephalexin, even when administered for about half the number of days.

Specifically, 1,267 patients were randomized to receive oritavancin once daily for three to seven days followed by oral placebo or vancomycin for three to seven days, followed by oral cephalexin for a total course of 10 to 14 days in both treatment arms. The primary efficacy endpoint of clinical cure of infection and the secondary measure of bacteriological eradication were met, demonstrating oritavancin was as effective as the comparator agents despite being administered for an average of only 5.3 days compared to 10.9 days for the vancomycin/cephalexin group. Also, oritavancin showed an improved safety profile with a 19.2 percent relative reduction in the overall incidence of adverse events vs. vancomycin/cephalexin (p<0.001).

InterMune said it would submit the data for presentation at an appropriate meeting.

However, it was the faltering Actimmune sales news that ruled the day, as Bear Stearns, RBC Capital Markets, Adams Harkness, Needham & Co. and Banc of America Securities all downgraded InterMune.