Keep an Eye on BioMarin, Amgen, Merck, and AstraZeneca Today

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.

Good morning, fellow Foolish investors! Let's take a look at four stocks you should watch today -- BioMarin Pharmaceutical (BMRN 2.87%), Amgen (AMGN 0.60%), Merck (MRK -0.05%), and AstraZeneca (AZN 1.03%).

BioMarin gets halted ahead of an FDA advisory meeting
The first stock I'll talk about today is BioMarin Pharmaceutical, which is now halted ahead of an FDA advisory meeting today to review the company's application for Vimizim, an enzyme replacement therapy for patients with Morquio A syndrome, a rare lysosomal storage disorder.

Morquio A is a debilitating disease that renders the patient's body unable to process certain types of mucopolysaccharides -- resulting in a wide variety of symptoms, including heart, skeletal, and spinal problems. To date, there are no approved treatments for the disease, which means BioMarin's treatment would be a huge step forward if approved. A prior FDA review for Vimizim was mixed -- the treatment helped patients walk 22.5 meters farther than with a placebo, but made no noticeable difference in a three-minute stair-climb test.

BioMarin has four other approved products in its portfolio -- Naglazyme (MPS VI), Kuvan (PKU), Aldurazyme (MPS I), and Firdapse (Lambert-Eaton myasthenic syndrome). Of these drugs, Naglazyme is the most important, accounting for 47% of the company's revenue last quarter. However, sales of Naglazyme only rose 0.7% year over year last quarter. Kuvan, which accounts for 32% of BioMarin's top line, is its fastest-growing treatment, reporting 7.2% growth.

If approved, Vimizim is expected to generate peak sales of $500 million by 2020 -- not blockbuster levels, but also not a bad boost for a company that only generated $500.7 million in revenue in fiscal 2012.

Amgen and Merck provide updates regarding their melanoma treatments
We should also take a look at two new developments in skin cancer treatments from Amgen and Merck.

Yesterday, Amgen presented interim data from its phase 3 study of talimogene laherparepvec, its treatment for metastatic melanoma, or late-stage skin cancer. The drug is an oncolytic drug which kills cancer cells and helps the body's immune system recognize and destroy cancer cells.

Amgen's trial compared the drug against a granulocyte-macrophage colony-stimulating factor (GM-CSF) treatment, which stimulates white blood cell growth. The median overall survival rate in patients given talimogene laherparepvec was 23.3 months, compared to 19 months in the GM-CSF group. Amgen reported that the most frequent side effects of its drug were fatigue, chills, and fever. Serious adverse events occurred in 26% of patients given Amgen's drug, compared to 13% of GM-CSF patients. More detailed results from the trial are expected during the first half of 2014.

Meanwhile, Merck reported interim data from its phase 1b trial testing its new cancer drug, MK-3475, on advanced skin cancer. Merck stated that patients taking the therapy for one year exhibited an overall survival rate of 81% across all evaluated doses. However, median duration of response and median overall survival rates have not been reached yet.

MK-3475 is an anti-PD-1 immunotherapy antibody, a new type of treatment that targets the cellular immune switch for programmed death known as PD-1. Anti-PD-1 treatments are believed to be able to restore the immune system's ability to recognize and eliminate cancer cells. MK-3475 is also being tested as a treatment for lung cancer.

The announcements put Amgen and Merck on an eventual track to challenge Roche and Bristol-Myers Squibb in the market for melanoma treatments. Roche's Zelboraf was approved by the FDA in 2011 and the EU in 2012 for the treatment of late-stage melanoma. Bristol-Myers' Yervoy was approved in the U.S. and Europe in 2011 for the same indication. The market for these treatments is growing -- the number of metastatic melanoma cases is projected to increase 43% by 2015.

AstraZeneca's NDA for naloxegol is accepted
Last but not least, AstraZeneca reported that the FDA had accepted its new drug application (NDA) for naloxegol, a treatment for constipation caused by opioid painkillers. The acceptance was based on data from four phase 3 trials.

The acceptance of the NDA triggers a $70 million payment to Nektar Therapeutics (NKTR 4.41%), which provided the technology to develop the drug as part of a license agreement signed in 2009.

Naloxegol is a potential blockbuster drug that could hit annual peak sales of $1.5 billion, according to analysts at JPMorgan. That high figure is due to the projection that 40% to 50% of patients taking opioids for chronic pain develop constipation, representing a prospective market of 28 million to 35 million patients worldwide. Only 40% to 50% of that market have received satisfactory treatment using over-the-counter and prescription laxatives, according to Nektar.