For companies that are developing new and innovative treatments, few events can move the share price as much as the results of clinical trials. For clinical-stage biotechs, trial results are a huge indicator of potential future success. With this in mind, there are a variety of companies that are expecting key clinical trial results relatively soon. Now, biotech stocks aren't for the faint of heart -- each of these three companies is burning through cash, and so investors should exercise appropriate caution when considering 

Xoma Corporation (NASDAQ:XOMA) is expecting clinical trial results for its drug Gevokizumab. Gevokizumab is being developed in a variety of indications, however, the trial that they are expecting results for is in a phase 3 trial for Behcet's disease. The results for the phase 3 trial called EYEGUARD-B are expected before the end of June.

This trial is very important for Xoma, as its success would validate Gevokizumab's mechanism of action and also bring this flagship drug a step closer to commercialization. Gevokizumab is being tested in a variety of indications including non-infectious uveitis as well as pyoderma gangrenosum, for which the drug recently obtained Orphan Drug designation.

If approved by the FDA, Xoma's partner Servier would handle most of the marketing for the drug, which would provide revenue for Xoma essentially without cost (although Xoma has commercialization rights in the U.S. and Japan for all indications aside from cardiovascular disease and diabetes). With a net loss of $4.7 million reported for the first quarter of 2014 (and excluding the revaluation of warrant liabilities, that loss would have ballooned to $24.7), Xoma needs the money. The company's cash position ($94 million in cash and $60 million in operating cash flow burned over the past 12 months) highlights the importance of this drug getting to market.

GW Pharmaceuticals (NASDAQ:GWPH) is expecting results later this year from a phase 2a clinical trial for its drug GWP42003 in patients with ulcerative colitis. GW is also testing the drug for a schizophrenia indication in another 2a trial, with data expected in late 2015.

Sativex, which is GW Pharma's flagship drug, is approved in a variety of countries for MS Spasticity, and is is also expecting data from a phase 3 clinical trial for Sativex. This trial is very important to GW as it would provide the basis for a New Drug Application with the FDA and would help to get Sativex on the market in the U.S. Sativex is already approved in many countries for the treatment of MS Spacity (notably not the United States), so approval for Sativex would help to get the drug on the market with the potential to later expand Sativex's label within the United States. With a net loss of $8.7 million last quarter, GW needs more approvals and revenue -- and Sativex's phase 3 may be its best opportunity.

Opko Health (NASDAQ:OPK) is expecting clinical trial results for its drug Rayaldee for vitamin D insufficiency which is the subject of several phase 3 trials. Top-line data for the trials (which test the drug's efficacy in treating secondary hyperparathyroidism) are expected in mid-2014 with a potential NDA filed in early 2015.

Opko appears to be planning on launching Rayaldee by itself, and has been busy securing a supply chain for the drug. Opko needs sales to turn toward profitability, and given that the company burned through over $72 million in the trailing-12 months and has about $156 million in cash reserves, that turn is needed.

With this in mind, Opko's drug Rolapitant is on track for a mid-2014 NDA filing, so this drug should also help to bridge the gap in terms of Opko's operating losses.

Final thoughts
Each of the drugs mentioned in this article have the potential to substantially impact the future at each company. Investors should watch closely for hints of success in these trials, and should be able to adjust their investment strategies accordingly. It's also important to note that success in the lab doesn't necessarily translate to marketing success, so even if these drugs make it past the FDA, there will be additional challenges ahead.