BioWorld International Correspondent

Arpida AG remains on track to file for marketing approval for the intravenous antibiotic iclaprim in the U.S. and Europe before the year-end, following positive topline data from a second pivotal trial of the compound in patients with complicated skin and skin structure infection (cSSSI).

In the ASSIST-2 trial, iclaprim, a diaminopyrimidine that inhibits the bacterial enzyme dihydrofolate reductase, attained the primary endpoint by demonstrating non-inferiority in comparison with linezolid, marketed as Zyvox by New York-based Pfizer Inc.

Iclaprim (n=251) achieved an overall clinical cure rate of 84.9 percent, vs. 87.2 percent for linezolid (n=243) in the intent-to-treat population of 494 patients enrolled in the study. Data derived from clinically evaluable patients yielded cure rates for 89.6 percent and 96.4 percent for iclaprim and linezolid, respectively.

In the ASSIST-1 study, reported late last year, iclaprim achieved an overall clinical cure rate of 85.5 percent vs. 91.9 percent for linezolid in the intent-to-treat population of 497 patients enrolled in that study. Among clinically evaluable patients, the cure rates were 93.8 percent and 99.1 percent for iclaprim and linezolid, respectively. (See BioWorld International, Dec. 6, 2006.)

Reinach, Switzerland-based Arpida, which originally licensed iclaprim from Basel, Switzerland-based F. Hoffmann-La Roche Ltd., retains global rights to manufacture and commercialize the compound, and it plans to market the product solo in the U.S.

"We believe there is a good marker out there, which is [Lexington, Mass.-based] Cubist Pharmaceuticals Inc., with their drug cubicin. The feasibility of marketing [iclaprim] is there, and there are precedents for this," Arpida CEO Khalid Islam said in a conference call.

Shareholders responded positively to the news, pushing up the company's share price to an historic high of CHF45.45 (US$37.80 ) during trading on the Swiss Stock Exchange in Zurich Monday. It closed the day at CHF41.05, a gain of more than 18 percent on its previous close of CHF34.75.

Analyst sentiment on the stock is mixed, however. Markus Metzger, at Vontobel AG in Cologne, Germany, has set a target price on the stock of CHF51. Frankfurt-based Deutsche Bank AG is even more bullish, with a target price of CHF70, according to several media reports.

"For me, it's an immediate takeover target actually, on the basis of the current valuation," Metzger told BioWorld International. The company currently is valued at about CHF780 million. He is forecasting peak sales of CHF800 million for intravenous and oral versions of iclaprim in the cSSSI indication, and another CHF400 million in lung infection, although he is attaching a low probability to iclaprim gaining approval in the latter indication at present.

Positive news on the oral version of iclaprim, which is in early clinical development, and in the pneumonia indication could further drive up the share price. "Wait for Arpida to outperform the market in the coming months," Metzger said.

Olav Zillian, analyst at Geneva-based Helvea SA is less convinced of Iclaprim's potential, however, and believes the stock to be overpriced at present. His price target is CHF32. "That's pretty stretched," he told BioWorld International. New York-based Goldman Sachs Group, Inc., is even less optimistic, with a reported price target of CHF27.

How the FDA interprets the statistical data from the two trials also could influence the label iclaprim obtains. Because the cure rates were so high in the ASSIST-1 study, it might lead to the conclusion that the patients were not suffering from severe infections. "The data would not be consistent," he said.

Zillian also cited the absence of a partnership and future potential problems with resistance to iclaprim among his concerns.

A Dutch in vitro study presented at a conference in 2003 indicated that isolates resistant to trimethoprim showed weakened susceptibility to iclaprim as well. His peak sales forecast in all indications is CHF280 million.