Isis Pharmaceuticals (NASDAQ: ISIP) reported encouraging resultsfrom Phase I/II clinical trials of ISIS 2922, its antisense oligonucleotidedrug for treating cytomegalovirus (CMV)-induced retinitis in AIDSpatients. The results were presented Thurday at the annual meeting ofthe Federation of American Societies for Experimental Biology inAnaheim, Calif.ISIS 2922 inhibits the production of proteins required for CMVreplication. The drug is designed to bind only to certain sites on aparticular messenger RNA of CMV. It is being developed forintravitreal use in collaboration with Eisai Co. Ltd, a Japanesepharmaceutical company that has assumed half the development costs.The companies will co-promote ISIS 2922 and share equally inmarketing when approved.CMV retinitis is an opportunistic viral infection that affects AIDSpatients and other immunosuppressed individuals. It may causepermanent damage to the retina and lead to blindness.The trial was conducted in 10 patients, male and female, with advancedCMV infection and advanced AIDS. All had failed to respond, orbecome intolerant to either or both of the standard treatments,ganciclovir or foscarnet. ISIS 2922 was administered by intravitrealinjection once a week for four weeks and every two weeks thereafter.Two patients received a low dose, three a middle dose, and five a highdose of the product. Progression of CMV retinitis was measured bystandard criteria for the disease.Isis' president and CEO, Stanley Crooke, said ISIS 2922 was welltolerated at all doses. He said some "ocular events" were observed butthey were not significant and may not have been associated with thedrug. Patients receiving the low dose did not respond, but two of thethree patients in the middle dose group and all in the high dose groupshowed positive clinical responses.Crooke said there have been no relapses in the treated eye among thepatients, who have been followed for periods ranging from four to 18weeks after trial. In two cases, however, patients developed CMVinfection in the untreated eye.Crooke said the company plans to begin Phase II/III trials this summer.He predicted that the drug, when approved, would be priced verycompetitively with ganciclovir or forscarnet.Crooke noted that clinical trials of ISIS 2922 as a systemic treatmentfor CMV pneumonia and gastroenteritis are also planned in the future.Eisai will not be involved in these trials and other partners are beingconsidered, he said. n

-- Philippa Maister

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