Though speculators' eyes may be on bitcoin and other cryptocurrencies at the moment, arguably no group of stock-based equities has been stronger over the trailing year than marijuana stocks. If we look at some of the catalysts behind the pot industry, it's not hard to see why investors are seeing green.

Perhaps the biggest factor moving marijuana stocks is the public's rapidly changing opinion toward cannabis. National pollster Gallup, which has periodically taken polls on the public's opinion of legalizing weed, found that only 25% of its respondents supported such a measure in the mid-1990s. Comparatively, an all-time record high of 60% wanted to see weed legalized across the U.S. based on its most recent poll in Oct. 2016. The higher this favorability rating goes, presumably the more pressure that'll be put on lawmakers in Washington to elicit change in the federal law governing marijuana.

An outdoor commercial cannabis grow farm.

Image source: Getty Images.

We've also witnessed some mind-boggling sales growth from legal cannabis. Colorado wound up growing legal weed sales by more than 30% in 2016 to north of $1.3 billion, while North American legal marijuana sales are estimated to grow by 26% per year between 2016 and 2021 , according to cannabis research firm ArcView. If this estimate proves accurate, the North American legal marijuana market would be worth nearly $22 billion by 2021.

Then again, the glass ceiling on pot stocks remains firmly in place thanks to the federal government's Schedule I categorization of the drug. Schedule I means marijuana has no medical benefits, and it's wholly illegal, just like heroin and LSD. This scheduling keeps most marijuana-based businesses from obtaining basic banking services, and it also keeps them from taking corporate income-tax deductions since they're selling a federally illegal substance. Lastly, a Schedule I status makes it incredibly tough for researchers to get the OK to run clinical studies into the safety, benefits, and risks, of medical cannabis.

These two pot stocks were on fire last week

This bifurcation between legal U.S. states and the federal government has created a lot of volatility among marijuana stocks, with double-digit percentage moves becoming quite common. Last week, two marijuana stocks in the drug-development space moved decisively higher after announcing upcoming data releases. Let's take a quick look at these budding pot stocks and see whether these moves higher are justified.

A biotech lab researcher using a microscope.

Image source: Getty Images.

Cara Therapeutics

Few marijuana stocks have been more volatile of late than Cara Therapeutics (NASDAQ:CARA), which has seen its lead drug, CR845 -- a kappa opioid receptor agonist, which has nothing to do with cannabis -- succeed in some studies and fail in others. In particular, CR845 is being targeted at treating moderate to severe pruritus (itching) associated with chronic kidney disease and various forms of chronic pain. Pain is a much larger and profitable patient pool compared to pruritus, but it's pruritus where CR845 has been successful, whereas chronic pain has been disappointing.

In late June, Cara released highly anticipated phase 2b data for CR845 as a treatment for patients with osteoarthritis (OA) of the hip of knee. Of the three doses tested, the two lower doses did not produce statistically significant results, while the high dose (5 mg) reached statistical significance in one portion of the study -- OA of the hip. Cara's shares wound up losing more than half their value in two weeks following the news.

The silver lining here, though, is that Cara can choose to reload the study to solely focus on OA of the hip, or perhaps try a higher dose. It also has an exciting ongoing late-stage study (Clin3001) involving intravenous CR845 for the treatment of postoperative pain that was given the green light by the independent data monitoring committee at a planned interim analysis to continue. In other words, CR845 may still have legs in treating pain. And let's not forget that Cara also has CR701, a cannabinoid-receptor agonist that tethers it to marijuana stocks, in its back pocket.

This past week, Cara's shares bounced 9% after the company announced its intention to present data from its phase 2 OA trial at PAINWeek, being held the week of Sept. 5 through Sept. 9.  There's the possibility that this presentation could give clues as to what Cara plans to do next given its mixed OA trial results. While not sold on Cara Therapeutics, it could be only a phase 3 success in postoperative pain away from a much higher valuation.

A doctor holding a cannabis leaf between his hands.

Image source: Getty Images.

Corbus Pharmaceuticals

However, for the second week in a row Corbus Pharmaceuticals (NASDAQ:CRBP) was the top-performing marijuana stock. For the week, Corbus' stock wound up gaining nearly 12%, and is up 30% over the past two weeks.

The catalyst this past week looks to be an announcement from the company regarding a fireside chat on Sept. 5 to discuss dermatomyositis with expert physician and research Victoria Werth, M.D. Corbus has just one drug candidate in clinical trials, albeit this drug candidate, anabasum, is being targeted at four indications, of which dermatomyositis is one. Currently in midstage studies, Corbus' single-center trial is being conducted at the University of Pennsylvania School of Medicine and is being fully funded by a grant from a subdivision of the National Institutes of Health.

While this press release could be drumming up support for anabasum, investors would be wise to keep their expectations in check with little in the way of strong clinical data backing up the drug as of yet. For instance, even though anabasum produced a 75% reduction in the pulmonary exacerbation event rate in a midstage study in cystic fibrosis (CF), unquestionably the most profitable indication of the four being studied, it also failed to lead to an improvement in lung function for CF patients as measure by forced expiratory volume in the first second (FEV1). Food and Drug Administration-approved CF drugs are few and far between, but they have demonstrated FEV1 improvements in clinical studies, which casts doubt over anabasum's effectiveness.

The allure of anabasum in CF is that it would probably be a general use anti-inflammatory as opposed to a drug used to treat a specific CF mutation. The big question that remains unanswered is: Does it really work? For now, this writer would suggest investors stick to the sidelines and wait for concrete later-stage data on anabuasum's effectiveness.

Sean Williams has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.