This week, the overall grades of 12 biotechnology stocks are lower, according to the Portfolio Grader database. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

CEL-SCI Corporation’s (CVM) rating falls to a D (“sell”) this week, down from C (“hold”) the week prior. CEL-SCI is developing new immune system based treatments for cancer and infectious diseases. In Portfolio Grader’s specific subcategories of Equity and Cash Flow, CVM also gets F’s. To get an in-depth look at CVM, get Portfolio Grader’s complete analysis of CVM stock.

EPIRUS Biopharmaceuticals, Inc. (EPRS) is having a tough week. The company’s rating falls from a C to a D. The stock also rates an F in Earnings Revisions. For more information, get Portfolio Grader’s complete analysis of EPRS stock.

This week, Ohr Pharmaceutical Inc’s (OHRP) rating worsens to a D from the company’s C rating a week ago. Ohr Pharmaceutical develops pharmaceuticals for wound care and to treat cachexia. The stock gets F’s in Earnings Revisions and Equity. To get an in-depth look at OHRP, get Portfolio Grader’s complete analysis of OHRP stock.

Trius Therapeutics, Inc. (TSRX) gets weaker ratings this week as last week’s C drops to a D. Trius Therapeutics is a biopharmaceutical company. The stock gets F’s in Earnings Growth, Earnings Momentum and Equity. Cash Flow and Sales Growth also get F’s. For more information, get Portfolio Grader’s complete analysis of TSRX stock.

The rating of Vical Incorporated (VICL) declines this week from a C to a D. Vical researches and develops biopharmaceutical products based on its patented DNA delivery technologies for the prevention and treatment of serious or life-threatening diseases. The stock gets F’s in Equity and Cash Flow. To get an in-depth look at VICL, get Portfolio Grader’s complete analysis of VICL stock.

Tenax Therapeutics, Inc.’s (TENX) rating falls this week to an F (“strong sell”), down from last week’s D (“sell”). The stock receives F’s in Earnings Momentum, Earnings Revisions and Equity. Cash Flow and Sales Growth also get F’s. For more information, get Portfolio Grader’s complete analysis of TENX stock.

Slipping from a C to a D rating, Adamas Pharmaceuticals, Inc. (ADMS) takes a hit this week. The stock gets F’s in Earnings Growth, Earnings Momentum and Earnings Revisions. Margin Growth and Sales Growth also get F’s. The stock has a trailing PE Ratio of 33.50. To get an in-depth look at ADMS, get Portfolio Grader’s complete analysis of ADMS stock.

The rating of Synergy Pharmaceuticals, Inc. (SGYP) declines this week from a D to an F. Synergy Pharmaceuticals is a biopharmaceutical company focused on the development of drugs to treat gastrointestinal disorders and diseases. The stock gets F’s in Equity and Cash Flow. As of May 6, 2015, 18.6% of outstanding Synergy Pharmaceuticals, Inc. shares were held short. Shares of the stock have been exchanging at an usually rapid pace, twice the rate of the week prior. For more information, get Portfolio Grader’s complete analysis of SGYP stock.

Lexicon Pharmaceuticals, Inc. (LXRX) is having a tough week. The company’s rating falls from a C to a D. Lexicon Pharmaceuticals researches treatments for diabetes and obesity, cardiovascular disease, psychiatric and neurological disorders, cancer, immune system disorders, and ophthalmic disease. The stock gets F’s in Equity and Cash Flow. To get an in-depth look at LXRX, get Portfolio Grader’s complete analysis of LXRX stock.

Verastem, Inc. (VSTM) earns an F this week, moving down from last week’s grade of D. Verastem is a biopharmaceutical company which is focused on discovering and developing novel drugs that selectively target cancer stem cells in breast and other cancers along with proprietary companion diagnostics. The stock gets F’s in Equity and Cash Flow. As of May 6, 2015, 10.1% of outstanding Verastem, Inc. shares were held short. For more information, get Portfolio Grader’s complete analysis of VSTM stock.

Celldex Therapeutics, Inc. (CLDX) gets weaker ratings this week as last week’s C drops to a D. Celldex Therapeutics is engaged in the discovery, development and commercialization of products that harness the human immune system to prevent and treat disease. The stock also gets an F in Equity. As of May 6, 2015, 16.2% of outstanding Celldex Therapeutics, Inc. shares were held short. To get an in-depth look at CLDX, get Portfolio Grader’s complete analysis of CLDX stock.

This week, Trevena, Inc.’s (TRVN) rating worsens to a D from the company’s C rating a week ago. The stock gets F’s in Equity and Cash Flow. For more information, get Portfolio Grader’s complete analysis of TRVN stock.

Louis Navellier’s proprietary Portfolio Grader stock ranking system assesses roughly 5,000 companies every week based on a number of fundamental and quantitative measures. Stocks are given a letter grade based on their results — with A being “strong buy,” and F being “strong sell.” Explore the tool here.