As I mentioned previously in Part 1, it was an incredibly busy week for the biotech sector. A PDUFA decision, as well as three FDA panel reviews/findings provided the impetus for some big moves; however, that was only part of the story.

Four other biotech companies released clinical-stage data that certainly moved the needle for shareholders. Here's a look at those four key stories.

No company stole the show more than Vertex Pharmaceuticals (NASDAQ:VRTX), which skyrocketed 62% on Friday after the combination of VX-661 and Kalydeco, its already FDA-approved cystic fibrosis treatment, delivered results far and above anyone's expectations in mid-stage trials. Of the four dosing levels being tested, the two highest doses delivered an FEV-1 improvement (a test that measures the amount of air a person can exhale within the first second) of 9% and 7.5%, respectively. By comparison, the placebo delivered just a 3% improvement in FEV-1. Considering that the treatment was well tolerated, Vertex may have found its next area of clinical dominance in cystic fibrosis.

This is also crucial, because Vertex's Incivek, an intravenous hepatitis-C treatment, is projected to face heavy competition from Gilead Sciences' (NASDAQ:GILD) oral hep-C treatment known as Sofosbuvir. Gilead's drug flew through all four late-stage trials, has been filed with the FDA as a new drug applicant, and could revolutionize hep-c treatments with fewer side effects. With multiple revenue sources, Vertex shareholders can definitely rest easier with VX661 and Kalydeco performing well in trials.

Acorda Therapeutics' (NASDAQ:ACOR) shares also soared this week by 28%, after the company reported positive mid-stage results for its post-stroke deficit drug, Ampyra. Results of the 83-person study demonstrated that Ampyra improved walking ability and increased functional independence in patients who'd had an ischemic stroke within six months of enrollment. More importantly, the side effects were predominantly minimal, meaning Acorda may soon have yet another drug to add to its pipeline of products.

Not wanting to be outdone, Alkermes (NASDAQ:ALKS) shares surged 25% on the week as well, following positive mid-stage results for its major depressive disorder drug, ALKS-5461. The oral ALKS-5461 met its primary endpoint of changing the baseline in depressive symptoms over the four-week period of the trial as defined by the Hamilton Depression Rating Scale. While the Street seems hopeful that this news should expedite ALKS-5461 into the next stage of development, I remain concerned that as an opioid-modulating drug, it could be construed in some way as addictive even though Alkermes labels it as a non-addictive drug. This is one case I'd stay away from until (if it makes it that far) the FDA panel has its say.

Finally, even big pharma Eli Lilly (NYSE:LLY) got in on the action, noting that two additional late-stage trials for dulaglutide, its GLP-1 diabetes drug hopeful, met their primary endpoints. In both studies, known as Award-2 and Award-4, dulaglutide matched insulin glargine in reducing hemoglobin A1C levels, which was the endpoint of the studies. Furthermore, it beat the differing placebos in terms of A1C reductions in both studies. Diabetes research is a huge market that only seems to be growing, so having additional strong late-stage results like this should help to strengthen the company's case for an eventual FDA approval.

Fool contributor Sean Williams has no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong, track every pick he makes under the screen name TrackUltraLong, and check him out on Twitter, where he goes by the handle @TMFUltraLong.

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