Updated from 2:41 p.m. EDT

Shares of Immune Response ( IMNR) were among the worst-performing health-related stocks Monday, falling 30.5% after the company said that its auditor, Levitz, Zacks & Ciceric, expressed substantial doubt about the company's ability to continue as a going concern.

The biopharmaceutical company, which has seen its shares drop by about 65% during the past year, said it issued the press release because Nasdaq rules require Nasdaq-listed companies to publicly announce the information whenever a company receives a going-concern qualification in a 10-K filing. In the 10-K filing, issued March 25, the company said that it may not be able to generate sufficient product revenue to become profitable on a sustained basis, or at all, and said it does not expect to generate significant revenue before the end of 2008. It cited "operating and liquidity concerns due to our significant net losses and negative cash flows from operations" and said it needs more capital before the third quarter of 2005 in order to survive. Shares traded down 25 cents to 57 cents.

aaiPharma ( AAII) slumped 15.7% after the company said that it failed to make an April 1 interest payment, and reiterated its belief that it is "highly likely" that it would seek bankruptcy protection. If the company fails to make the missed interest payment within 30 days of April 1, holders of 25% of the outstanding amount of the notes or the trustee under the indenture may declare the outstanding amount of the notes immediately due and payable. In an attempt to restructure the debt, the company, it said, will continue to discuss the situation with a committee representing the holders of the notes. Shares traded down 11 cents to 59 cents.

Shares of Weider Nutrition International ( WNI) fell 7.6% after the company posted third-quarter earnings that fell below expectations. The maker of nutritional supplements posted earnings of $1.2 million, or 5 cents a share, on sales of $65.6 million. An analyst polled by Thomson First Call had been expecting earnings of 8 cents a share. A year ago Weider posted earnings of $2.6 million, or 10 cents a share, on sales of $67.5 million. Third-quarter sales were hurt by a decline in domestic private label sales and by weakness in its Haleko branded sales. Gross margins suffered because of volatile raw-material costs in its joint-care business, increased marketing spending related to new products and disappointing Haleko branded sales. Shares traded down 48 cents to $5.80.

Curis ( CRIS) rose 6% after the company disclosed a collaboration with Genentech ( DNA) involving the discovery and development of small molecule modulators that play an important role in cell proliferation. Under the terms of the deal, Genentech will pay Curis an upfront fee of $3 million and up to an additional $6 million over the next two years, which will be used to support research. The agreement also calls for Genentech to make cash payments to Curis if certain developmental, clinical and drug approval milestones are met. Total payments, excluding royalties, could reach as much as $140 million if two products are commercialized in two indications each, Curis said. Shares traded up 22 cents to $3.91.

Shares of Molina Healthcare ( MOH) fell 1.3% after the company said that it would sell 3 million shares in a follow-on stock offering. Of the 3 million shares, the company is selling 1 million shares while three selling shareholders are selling the rest. The company plans to use the proceeds from its portion of the sale for working capital and general corporate purposes. Shares of the managed care organization traded down 60 cents to $45.40.

Other health care movers included Elan ( ELN), up 28 cents to $3.66; Pfizer ( PFE), down 22 cents to $25.93; Merck ( MRK), up 19 cents to $32.50; Johnson & Johnson ( JNJ), up $1.13 to $67.98; Amgen ( AMGN), down 2 cents to $57.33; and Schering-Plough ( SGP), up 9 cents to $17.98.