Updated from 2:57 p.m. EST

Shares of Aphton ( APHT) were among the worst-performing health-related stocks Tuesday, falling 45.7% after the biopharmaceutical company said that its pancreatic cancer drug, Insegia, did not meet its primary endpoint of improving overall survival rates in a phase III clinical trial.

"While Insegia did not meet the primary endpoint, we are encouraged by results we have observed in patients who achieved an antibody response, in this case approximately 70% of patients," the company said. The company believes the positive results seen by the 70% of patients who received a combination of Insegia and chemotherapy is important because it will help the company design future clinical trials that combine Insegia and chemotherapy. Shares traded down $1.43 to $1.70.

Salix Pharmaceuticals ( SLXP) fell 6.1% after the company posted in-line fourth-quarter results and forecast 2005 earnings that would match expectations. The drug developer posted fourth-quarter earnings of $3.6 million, or 9 cents a share, on sales of $28.9 million. Analysts polled by Thomson First Call were expecting earnings of 9 cents a share on sales of $28.4 million. Looking ahead, the company forecast 2005 earnings of at least 60 cents a share on sales of $150 million to $155 million. Analysts are expecting earnings of 60 cents a share on sales of $146.8 million. Shares traded down $1.09 to $16.76.

Shares of Altair Nanotechnologies ( ALTI) fell 15% after the company announced the sale of 5 million shares of stock at $4.05 apiece. After the deal closes, Altair expects net proceeds of about $19.2 million. The sale price represents an 18% discount to Monday's closing price of $4.95. Altair said it would use proceeds from the offering to fund working capital and general corporate needs. Shares of Altair have climbed more than 55% since the beginning of the year. Shares traded down 74 cents to $4.21.

Charles River Laboratories ( CRL) rose 8.7% after the company posted fourth-quarter results that beat expectations. Excluding items, the company earned $31.2 million, or 48 cents a share, on sales of $238.1 million. Analysts were expecting earnings of 47 cents a share on sales of $227 million. A year ago, the company earned $20.6 million, or 42 cents a share, on sales of $156 million. Looking ahead, Charles River forecast first-quarter earnings of 54 cents to 56 cents a share, in line with expectations, on sales growth of 57% to 60%. Analysts are looking for sales of $272.4 million, or sales growth of 58%. Shares traded up $4.06 to $51.

Shares of WellCare Health Plans ( WCG) fell 8.6% after the company posted solid fourth-quarter results but warned that first-quarter earnings would fall short of expectations. The company posted earnings of $17.7 million, or 46 cents a share, on sales of $397.3 million. Analysts were expecting earnings of 44 cents a share. Looking ahead, the company forecast first-quarter earnings of 23 cents to 25 cents a share on sales of $403 million to $408 million. Analysts had been expecting earnings of 32 cents a share. Shares traded down $3.28 to $34.67.

Other health care movers included Teva Pharmaceutical Industries ( TEVA), down $1.71 to $28.66; Pfizer ( PFE), down 26 cents to $25.22; Aastrom Biosciences ( ASTM), up 8 cents to $2.79; Merck ( MRK), down 6 cents to $29.35; Amgen ( AMGN), up 44 cents to $63.69; Johnson & Johnson ( JNJ), down 9 cents to $65.91; and Schering Plough ( SGP), down 18 cents to $19.25.