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 look at four biotech stocks -- Curis (NASDAQ:CRIS), Amgen (NASDAQ:AMGN), and Novartis (NYSE:NVS) -- all of which could loom large in health care headlines this Monday morning.

The FDA lifts its clinical hold on Curis' CUDC-427 trial
Curis is up 12% this morning after the FDA lifted a clinical hold on enrollment in its early stage trial of CUDC-427, an experimental treatment for advanced solid tumors and lymphomas.

The hold was originally placed in November, after a patient with advanced breast cancer died from acute liver failure a month after stopping the drug. The trial started in the third quarter of 2013, and was being tested with a chemotherapy drug called capecitabine in patients with a type of advanced breast cancer.

This is a positive development for Curis, but investors should note that CUDC-427 is still in phase 1 trials, and that the company's main source of revenue is Erivedge, an approved treatment for advanced basal cell carcinoma. Erivedge is also in phase 2 trials for operable basal cell carcinoma. The drug is being marketed by Roche's (NASDAQOTH: RHHBY) Genentech and Chugai units, and Curis receives royalties from net sales and milestone payments.

Amgen provides new data for AMG 145
Over the weekend, Amgen released new data from several phase 3 studies of AMG 145, a closely followed cholesterol treatment.

AMG 145 belongs to a new class of drugs known as PCSK9 inhibitors, which attempt to lower LDL "bad" cholesterol levels by stopping the PCSK9 enzyme from binding to LDL receptors and throttling their ability to lower LDL levels. There is currently an intense race between AMG 145, Sanofi and Regeneron's alirocumab, and Pfizer's RN-316 to become the first approved PCSK9 treatment for high cholesterol.

Treatment with AMG 145 resulted in a statistically significant reduction of LDL cholesterol levels of between 37% to 39%, when compared to patients dosed with ezetimibe (Merck's Zetia) who cannot tolerate statins. When combined with statins, AMG 145 showed a 55% to 76% reduction in LDL levels when compared to a placebo.

Analysts believe that AMG 145 could generate peak sales of over $4 billion if approved. Investors are hoping that the drug can decrease Amgen's dependence on Enbrel, its blockbuster arthritis treatment which generated $4.5 billion in sales in fiscal 2013.

Novartis' phase 3 trial for LCZ696 concludes early on positive data
Last but not least, Novartis announced that it is closing its PARADIGM-HF phase 3 trial of LCZ696, a drug for chronic heart failure, due to the early strength of interim results. Novartis' announcement was based on a unanimous decision by a Data Monitoring Committee that the primary endpoint of the trial -- delaying cardiovascular death and reducing heart failure hospitalizations versus the cardiovascular drug enalapril -- had been met. The trial tested the drug on over 8,000 patients.

The early end of the phase 3 trial suggests that Novartis is ready to pursue marketing authorization for the drug in the U.S. and Europe. If approved, analysts believe that LCZ696 could generate peak sales of $1 billion, which could help offset the company's upcoming troubles with the U.S. patent expiration of Diovan in 2012 and the upcoming patent expiration of Gleevec in 2015. Together, Diovan and Gleevec -- Novartis' two top-selling drugs -- generated sales of $8.2 billion in fiscal 2013.

Investors should remember that Novartis suffered a blow on March 27 when an FDA advisory committee voted against the approval of RLX030 (serelaxin) as a treatment for acute heart failure. RLX030 was expected to generate peak sales of $1 billion or more if approved.  

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.