This week, the ratings of 11 biotechnology stocks on Portfolio Grader are down. 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. For more information, get Portfolio Grader’s complete analysis of CVM stock.

The rating of EPIRUS Biopharmaceuticals, Inc. (EPRS) slips from a C to a D. The stock also gets an F in Earnings Revisions. To get an in-depth look at EPRS, get Portfolio Grader’s complete analysis of EPRS stock.

Slipping from a C to a D rating, Ohr Pharmaceutical Inc (OHRP) takes a hit this week. Ohr Pharmaceutical develops pharmaceuticals for wound care and to treat cachexia. The stock gets F’s in Earnings Revisions and Equity. Shares of the stock have been changing hands at an unusually rapid pace, up 437.4% from the week prior. For more information, get Portfolio Grader’s complete analysis of OHRP stock.

Trius Therapeutics, Inc. (TSRX) is having a tough week. The company’s rating falls from a C to a D. Trius Therapeutics is a biopharmaceutical company. The stock receives F’s in Earnings Growth, Earnings Momentum and Equity. Cash Flow and Sales Growth also get F’s. To get an in-depth look at TSRX, get Portfolio Grader’s complete analysis of TSRX stock.

Vical Incorporated (VICL) experiences a ratings drop this week, going from last week’s 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. For more information, 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 gets F’s in Earnings Momentum, Earnings Revisions and Equity. Cash Flow and Sales Growth also get F’s. Shares of the stock have been changing hands at an unusually rapid pace, four times the rate of the week prior. To get an in-depth look at TENX, get Portfolio Grader’s complete analysis of TENX stock.

This week, Synergy Pharmaceuticals, Inc. (SGYP) drops from a D to an F rating. 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 April 1, 2015, 16.6% of outstanding Synergy Pharmaceuticals, Inc. shares were held short. For more information, get Portfolio Grader’s complete analysis of SGYP stock.

This week, Verastem, Inc.’s (VSTM) rating worsens to an F from the company’s D rating a week ago. 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 April 1, 2015, 10.7% of outstanding Verastem, Inc. shares were held short. To get an in-depth look at VSTM, get Portfolio Grader’s complete analysis of VSTM stock.

This is a rough week for Celldex Therapeutics, Inc. (CLDX). The company’s rating falls to D from the previous week’s C. 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 rates an F in Equity. As of April 1, 2015, 19.8% of outstanding Celldex Therapeutics, Inc. shares were held short. For more information, get Portfolio Grader’s complete analysis of CLDX stock.

The rating of Trevena, Inc. (TRVN) declines this week from a C to a D. The stock gets F’s in Equity and Cash Flow. To get an in-depth look at TRVN, get Portfolio Grader’s complete analysis of TRVN stock.

Akebia Therapeutics, Inc. (AKBA) earns a D this week, moving down from last week’s grade of C. The stock gets F’s in Equity and Cash Flow. For more information, get Portfolio Grader’s complete analysis of AKBA 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.