One of the biggest movers heading into the middle of the week in the biotechnology space is Stemline Therapeutics, Inc. (NASDAQ:STML). The company just reported data from the final stage of a phase III trial of one of its lead development assets and – on the back of the news – has run to the tune of 30%.

The drug under investigation is a late stage asset called SL-401 and, with the now completed study, Stemline was trying to show that it could be used effectively to treat patients with a condition called blastic plasmacytoid dendritic cell neoplasm (BPDCN). For those new to this disease, it’s a rare disease of the bone marrow and blood that affects multiple organs, including the lymph nodes and the skin. It often presents as leukemia or evolves into acute leukemia.

Anyway, there’s basically no treatment on the market right now in this condition and the company was looking to get its asset on shelves in an attempt to fill the unmet need. And as per the latest data, it looks like there is a strong chance it’s going to be able to do exactly that. The primary endpoint of the study was based around complete response rate and overall response rate and – as per the data – a complete response rate of 54% (7/13) and overall response rate (ORR) of 77% (10/13) were recorded.

The trial was small, with an enrollment of only 13 patients, and so some will point to this as a potential stumbling block for the company when it goes in front of the agency in the US for regulatory approval.

This is a very rare condition, however, and since there are no options on the market right now (and given the fact that while there seem to be some degree of safety concerns, the alternative to side effects is death), it’s probably not enough to warrant the FDA turning the drug down outright.

As mentioned, the market s are trading up on Stemline in the wake of the news, suggesting wider sentiment believes that the latest data will be strong enough to underpin regulatory approval for the drug in this tough target market. At the open on Wednesday, Stemline will go for around $13.75, with premarket activity having added around an extra percentage point to the company’s market capitalization post-run.

Chances are, as the week matures, we will see a degree of further appreciation as the company outlines its plans for regulatory approval.

Another big mover this week is Mylan N.V. (NASDAQ:MYL) but, unfortunately for the company and its shareholders, it’s far from the positive move we’ve seen from Stemline. The company is wrapped up in what is turning out to be a pretty vast government probe in the US into potential price fixing. The investigation, which was brought by the attorneys general of 45 states and the District of Columbia, involves a total of 18 companies and covers a reported 15 individual drugs that are sold, developed or marketed by the companies in question and, if it plays out unfavorably for those accused, could prove to be a defining moment in the future of generic (and, indeed, branded) drugs in the US market.

So why is this impacting Mylan?

Well, Mylan is one of the companies that’s wrapped up in the probe and it’s – reportedly – one of the lead targets. This isn’t too surprising, given the size of the company (and it’s potential for control and collusion in this market) but, as yet, there’s been no confirmation or indication even that the company is concerned about the outcome.

That is, until this week.

The investigators have so far named only tow individuals (alongside the companies and drugs) as specific investigation targets. One of these individuals is Rajiv Malik, Mylan’s president and executive director. The company has released a statement outlining its stance on this individual highlighting and – as is to be expected – the stance is supportive of its helmsman. Here’s what was said:

“(the company) has deep faith in the integrity of its President, Rajiv Malik, and stands behind him fully. Mylan and Rajiv Malik both intend to defend this case vigorously, and we look forward to the opportunity to present a full defense.”

It doesn’t look like markets share this degree of confidence however – the company is down 7% on the news. That doesn’t seem like much but, when you consider that Mylan is a $20 billion company, it’s a significant discount.