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 stocks that could make health care headlines this morning -- Xoma (NASDAQ:XOMA), Biogen Idec (NASDAQ:BIIB), Agenus (NASDAQ:AGEN), and GlaxoSmithKline (NYSE:GSK)

Xoma stops testing arthritis drug
Shares of Xoma (NASDAQ:XOMA) may be in for a rough ride this morning, after the company announced that it would not proceed with late-stage studies of gevokizumab as an arthritis treatment, after two mid-stage studies failed to show a significant benefit in patients. Gevokizumab is the company's lead drug candidate.

However, that doesn't mean that gevokizumab is finished -- Xoma (NASDAQ:XOMA) is still testing the drug as a potential treatment for a variety of other indications, including acne, autoimmune ear disease, and non-infective scleritus. Xoma (NASDAQ:XOMA) doesn't have any marketed products, and generates the majority of its revenue from various license, collaborative, and contract fees.

Biogen acquires the rights to Eisai's Alzheimer's drugs
Meanwhile, Biogen Idec (NASDAQ:BIIB) just acquired the rights to Eisai's (OTC:ESALY) experimental Alzheimer's treatments E2609 and BAN2401. Biogen (NASDAQ:BIIB) will pay Eisai (OTC:ESALY) an upfront payment and fixed milestone payments based on approval and commercialization. Biogen (NASDAQ:BIIB) and Eisai (OTC:ESALY) will share development expenses and co-promote the two drugs. The two companies will share the revenue and profits from the two drugs if they are approved. The agreement also grants Eisai (OTC:ESALY) an option to jointly develop and market two of Biogen's (NASDAQ:BIIB) experimental treatments for Alzheimer's disease.

This is an interesting change of pace for Biogen (NASDAQ:BIIB), which is primarily known for its multiple sclerosis (MS) drugs Avonex, Tysabri, and Tecfidera. Tecfidera, in particular, is expected to become a blockbuster drug with peak sales of $3.8 billion.

Eisai (OTC:ESALY), on the other hand, was the original manufacturer of Aricept, the world's best-selling Alzheimer's treatment before it went off patent in 2010. Aricept helped slow cognitive decline, but failed to address the root cause of the disease, which is commonly believed to be caused by the formation of beta amyloid "brain plaques."

The deal may face skepticism from investors who remember Johnson & Johnson/Pfizer/Elan's bapineuzumab and Eli Lilly's solanezumab, two monoclonal antibodies which were intended to clear away brain plaques but failed to produce any significant results. Eisai's (OTC:ESALY) E2609 is a BACE inhibitor, similar to Eli Lilly's failed Alzheimer's drug LY2886721, and BAN2401 is a monoclonal antibody like bapineuzumab and solanezumab.

Agenus reports fourth quarter earnings
Agenus (NASDAQ:AGEN) -- which focuses on various experimental treatments for diseases such as malaria, cancer, Alzheimer's disease, and genital herpes through partnerships with GSK (NYSE:GSK), Johnson & Johnson, and Pfizer -- just reported its fourth quarter and full year earnings.

Agenus (NASDAQ:AGEN), which doesn't have any marketed products, reported a net loss of $0.16 per share, or $5.8 million for the quarter, compared to a loss of $0.23 per share, or $5.6 million, in the prior year quarter. For the full year, Agenus (NASDAQ:AGEN) reported a net loss of $1.12 per share, or $33.2 million, compared to a loss of $0.51 per share, or $12.1 million, in the previous year. Agenus (NASDAQ:AGEN) finished fiscal 2013 with $27.4 million in cash, but it gained net proceeds of approximately $56 million from a public offering completed in the first quarter of 2014.

Agenus' (NASDAQ:AGEN) most promising product is its QS-21 Stimulon Adjuvant, which can boost the effectiveness of various vaccines. GSK (NYSE:GSK)is currently partnered with Agenus (NASDAQ:AGEN) for four indications in late-stage trials using QS-21 -- malaria, non-small cell lung cancer, melanoma, and shingles. Pfizer and Johnson & Johnson are partnered with Agenus (NASDAQ:AGEN) in an Alzheimer's indication which is currently in phase 2 trials. Shares of Agenus (NASDAQ:AGEN) are up nearly 90% over the past three months on optimism regarding its late-stage pipeline.

Agenus (NASDAQ:AGEN) and Ludwig Cancer Research also announced the advancement of three monoclonal antibody checkpoint modulators into preclinical development. These modulators -- two GITR agonists and a CTLA-4 antagonist -- target cell surface checkpoint proteins which can control immune responses, and represent another way for Agenus (NASDAQ:AGEN) to diversify its pipeline.

GSK's HIV drug GSK744 could be a game changer
Last but not least, GSK's (NYSE:GSK) experimental HIV drug GSK744 generated a lot of excitement at an AIDS conference yesterday. According to an Associated Press report, researchers reported that the injected drug, which crystallizes in the blood and is released over a longer period than traditional HIV drugs, achieved "100% protection" from HIV in two studies with monkeys.

This means that if the drug passes clinical trials and is approved, it could allow HIV to be prevented through periodic injections, rather than condoms, in a similar manner as birth control pills. A drug that is already known to reduce the chance of HIV spreading between sexual partners is Gilead Sciences' Truvada.

GSK744 is currently being developed by ViiV Healthcare, a joint venture between GSK (NYSE:GSK), Pfizer, and Shionogi. GSK owns 76.5% of the joint venture, while Pfizer and Shionogi respectively own 13.5% and 10%.

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.