Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

Let's take a closer look at four companies -- Myriad Genetics (NASDAQ:MYGN), Bayer (OTC:BAYR.Y), Amgen (NASDAQ:AMGN), and Synta Pharmaceuticals (NASDAQ: SNTA) -- that could make health care headlines this morning.

U.S. court denies Myriad Genetics' request to block Ambry's similar cancer test
Myriad Genetics is set to plunge this morning after a U.S. court denied its motion to block rival Ambry Genetics from selling a similar version of its cancer test. Myriad stated that its patents were valid, enforceable, and had been infringed upon, but the latest ruling means that Myriad will have to head to court against Ambry to prove it.

Myriad is best known for its BRCA1 and BRCA2 diagnostic tests, which identify genes that can cause breast and ovarian cancers. The Supreme Court previously invalidated several of Myriad's patents, which has left the door open for competitors such as Ambry and Quest Diagnostics (NYSE: DGX).

Myriad acquired Crescendo Bioscience last month for $270 million in cash, adding diagnostic tests for inflammatory and autoimmune diseases to its portfolio. The Crescendo acquisition was aimed at diversifying Myriad's portfolio beyond its BRACAnalysis tests.

Despite the looming threat of generic competition, Myriad's top line growth has remained robust. Revenue from the company's BRACAnalysis tests jumped 28% year over year last quarter to $141.2 million, accounting for 69% of Myriad's total revenue. Shares of Myriad have rallied more than 50% over the past 12 months.

Bayer and Amgen's Nexavar fails late stage liver cancer trial
Meanwhile, Bayer and Amgen subsidiary Onyx announced today that their oral cancer drug Nexavar failed to meet its main target during a phase 3 trial. Nexavar was being tested as an additional adjuvant treatment for liver cancer patients who had no traces of the disease after surgery, but the drug ultimately failed its goal of improving recurrence-free survival.

Nexavar is already approved as a treatment for advanced liver kidney cancer, liver cancer that cannot be surgically removed, and metastatic differentiated thyroid cancer. The additional adjuvant approval would have boosted sales of Nexavar, which is marketed in more than 100 countries. Nexavar is expected to generate peak sales of $1.46 billion by 2018, up from $1.02 billion in fiscal 2012.

Bayer and Onyx each fund half of the development costs worldwide, excluding Japan, where Bayer pays for all product development. The two companies co-promote the drug within the U.S. and split profits and losses equally. Bayer holds exclusive foreign marketing rights to Nexavar, but the two companies split profits in all international markets excluding Japan.

Synta reports fourth-quarter and full-year earnings
Last but not least, Synta just reported its fourth-quarter and full-year earnings. The company, which has no marketed products, reported no revenue for the full year.

Synta reported a fourth-quarter net loss of $24.2 million, or $0.31 per share, compared to a net loss of $18.1 million, or $0.29 per share, in the prior-year quarter. For the full year, Synta posted a net loss of $90.2 million, or $1.27 per share, compared to a net loss of $62.8 million, or $1.06 per share, for the previous year. For the full year, research and development expenses jumped 45.5% year over year to $71 million, while year-end cash and equivalents fell 9% year over year to $91.5 million.

Looking ahead, all eyes are on Synta's ganetespib, an experimental heat shock protein 90, or Hsp90,  inhibitor that is in various mid- to late-stage trials for non-small cell lung cancer, breast cancer, ovarian cancer, and acute myeloid leukemia. Synta has had a very rocky ride over the past 12 months -- shares have fallen nearly 50% due to doubts regarding the future of Hsp90 drugs.

Several other high-profile Hsp90 drugs from Infinity Pharmaceuticals, Exelixis, Biogen, and Mylan have notably been suspended or terminated. Synta's CEO also resigned earlier this month and the company currently lacks a permanent leader.

Despite these challenges, the FDA granted ganetespib a fast-track designation last September for non-small cell lung cancer. If approved, ThinkEquity analyst Mani Mohindru believes that the drug could generate peak sales of $450 million to $500 million and put the fledgling biotech on the map.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.