This week, the ratings of five biotechnology stocks on Portfolio Grader are down. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

EPIRUS Biopharmaceuticals, Inc. (EPRS) is on the decline this week, earning a D (“sell”) after receiving a C (“hold”) last week. To get an in-depth look at EPRS, get Portfolio Grader’s complete analysis of EPRS stock.

This week, Trius Therapeutics, Inc. (TSRX) drops from a C to a D rating. 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. For more information, get Portfolio Grader’s complete analysis of TSRX stock.

The rating of Prosensa Holding NV (RNA) declines this week from a C to a D. To get an in-depth look at RNA, get Portfolio Grader’s complete analysis of RNA stock.

Onconova Therapeutics Inc. (ONTX) ratings are on the decline this week as the company earns an F (“strong sell”). Last week, it received a D (“sell”). The stock gets F’s in Equity, Cash Flow and Sales Growth. For more information, get Portfolio Grader’s complete analysis of ONTX stock.

Ambit Biosciences Corp. (AMBI) earns an F this week, falling from last week’s grade of D. The stock gets F’s in Earnings Momentum, Earnings Revisions and Equity. Cash Flow and Sales Growth also get F’s. To get an in-depth look at AMBI, get Portfolio Grader’s complete analysis of AMBI 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.