Shares of Genomic Health ( GHDX) were among the worst-performing health-related stocks Monday, slumping 17% after Piper Jaffray downgraded the stock to market perform from outperform. The firm also cut its price target on the stock to $14.50 from $18.50. Piper Jaffray cited increased regulatory risk concerning the company's only product, a breast cancer test called Oncotype DX, for the downgrade. Until the regulatory status of the test is cleared up, the firm said, an overhang on the stock could last for some six to 10 months. In late January, the Food and Drug Administration sent a letter to Genomic inviting the company to meet with regulators to discuss the regulatory status of the test and discuss ways in which the company could fulfill any FDA premarket review requirements that might apply. Shares recently were trading down $2.53 to $12.07. Oscient Pharmaceuticals ( OSCI) fell 8% Monday, even though the drugmaker posted better-than-expected fourth-quarter results. The company reported a loss of $17.1 million, or 22 cents a share, on revenue of $9.5 million. Analysts polled by Thomson First Call expected a loss of 29 cents a share and revenue of $9.1 million. A year earlier, the company recorded a loss of $32.3 million, or 43 cents a share, on revenue of $2.7 million. The company said its most recent results were fueled by strong sales of Factive tablets and Testim testosterone gel. Shares recently traded at $2, down 18 cents. Shares of Medicines Co. ( MDCO) fell 2% after the drug developer announced the resignation of its chief financial officer. The company said Steve Koehler, who had served as CFO for four years, will step down on March 17 to take a position with a pharmaceutical company. Koehler will be replaced by Glenn Sblendorio, who most recently served as chief financial officer at Eyetech Pharmaceuticals, which was acquired in November by OSI Pharmaceuticals ( OSIP). Medicines Co. shares were trading down 49 cents to $19.62.