* Cel-Sci Corp., of Alexandria, Va., changed the terms of its publicly held warrants. Holders of outstanding warrants were given the opportunity to buy one share of common stock and one Series A warrant for $6 and five warrants until Feb. 6. Originally, Series A warrant-holders were allowed to purchase one additional share of the company's stock for $18 anytime before Feb. 7, 2000.

* Isis Pharmaceuticals Inc., of Carlsbad, Calif., said its Phase III trial of ISIS 2922 (fomivirsen) resulted in statistically significant efficacy data, and more complete results will be presented in February at an AIDS conference. Fomivirsen, an antisense drug and Isis's lead product, was studied as a single-agent therapy and a combination therapy for the treatment of cytomegalovirus (CMV) retinitis in AIDS patients. The drug is being developed in a collaboration with CIBA Vision, of Atlanta, the eye care unit of Novartis AG, of Basel, Switzerland.

* Cypress Bioscience Inc., of San Diego, said results from its pivotal Phase III study of the Prosorba column for rheumatoid arthritis showed statistically significant safety and efficacy results. Prosorba, already on the market for treatment of idiopathic thrombocytopenic purpura (an immune-mediated bleeding disorder), is a disposable filter that uses protein A to remove circulating immune complexes, such as antibodies and antigens, that are believed to be responsible for autoimmune diseases. More data from the Phase III trial for arthritis will be presented at an upcoming scientific meeting.

* Genzyme Corp., of Cambridge, Mass., said its genetic diagnostic business unit has acquired certain assets of Prenatal Diagnostic Center Inc., a privately held laboratory in Lexington, Mass. The lab processes amniotic fluid, peripheral blood and tissue samples for chromosome analysis, biochemical and DNA assays, and maternal serum samples for birth defect screening. The purchase is part of Genzyme's strategy to expand into the genetic testing market.

* Gilead Sciences Inc., of Foster City, Calif., said a Phase I/II study of its nucleotide analogue, PMPA, showed oral administration as a monotherapy for HIV substantially decreased RNA levels of the virus at each of three dose levels, and was well tolerated. PMPA is an acronym for (R)-9-(2-phosphonylmetho-xypropyl) adenine. Data from the trial will be presented at the 5th Conference on Retroviruses and Opportunistic Infections, in Chicago.

* Immunomedics Inc., of Morris Plains, N.J., said its board of directors has adopted a standard shareholders' rights plan to guard against unwanted takeovers. The company said the move is not in response to any specific acquisition attempt.