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.

What: Shares of the developmental-stage cancer immunotherapy company Advaxis (NASDAQ:ADXS) fell by more than 10% today. Although there isn't a specific catalyst for this drop, it appears to reflect the growing doubts about the company after they were accused of fudging clinical trial results for an ongoing late-stage study and employing stock promoters over a year ago to artificially increase their share price.

Most importantly, Advaxis is said to have overstated the effectiveness of its experimental cancer therapy, ADXS-HPV, in reducing tumor size in patients with recurrent cervical cancer. Initially, the results of the study were reported in absolute (in millimeters) and not relative terms (% change in size), which makes it difficult to gauge the clinical benefit of the therapy.

Management has since updated its corporate presentation containing a graph illustrating the changes in tumor size on a percent basis. .   

So what: Advaxis has a long problematic operating history, pot-marked by several massive dilution events that wiped out early shareholders. The stock has seemingly found a second life, though, after the former CEO Thomas Moore stepped down and major players in immuno-oncology such as Merck took an interest in the company's bacteria-based (engineered Listeria monocytogenes) approach to cancer treatment. These recent allegations -- and the market's subsequent reaction -- nevertheless show that the stock will probably remain on the volatile side until the company is able to gain a regulatory approval for one of its clinical candidates. 

Now what: Advaxis is undoubtedly taking a novel approach to cancer treatment within the immuno-oncology space. Even so, the use of bacterial vectors to induce immune responses against tumors hasn't exactly produced stunning results so far. In a mid-stage study for ADXS-HPV, for instance, the treatment generated only a 6% response rate and overall survival appeared to be comparable to the use of chemotherapy alone.

Going forward, the company may have more luck with its platform in a combo setting, such as the planned study with Merck's PD-1 inhibitor Keytruda as a potential treatment for advanced prostate cancer. That said, you may want to wait until its bacterial-based therapy progresses further in clinical testing before jumping into this risky stock.