With the SPDR S&P Biotech Index up 64% over the trailing-12-month period, it's evident that investment dollars are willingly flowing into the biotech sector. Keeping that in mind, let's have a look at some of the rulings, studies, and companies that made waves in the sector last week.

As you might imagine, the annual J.P. Morgan Healthcare Conference this week made it practically impossible to jam-pack this week's most important stories into a single article. Instead, I'll be focusing on nine important news events, separated over two articles, which include five clinical updates, three Food and Drug Administration actions, and the announcement of a new collaborative pact.

Before we get into part one here which will cover five important clinical updates, I encourage you to review some of the most intriguing presentations of the J.P. Morgan Healthcare Conference, which include:

Walk the walk
Perhaps no clinical presentation raised more eyebrows than that of Sarepta Therapeutics (NASDAQ:SRPT), which reported the follow-up 120-week results from its ongoing mid-stage study of Duchenne muscular dystrophy, or DMD, treatment eteplirsen on Wednesday. According to its press release and presentation at the J.P. Morgan Healthcare Conference, walking stabilization continued to be apparent with the eteplirsen intent-to-treat group losing just 13.9 meters in the six-minute walk test, or 6MWT, since the baseline more than two years prior -- that's less than 5%! Even the placebo group has stabilized since being switched over to eteplirsen at Week 24 and has lost just 9 meters in the 6MWT since Week 36 through Week 120. Although Sarepta will still need to run a confirmatory phase 3 study, this data continues to point toward the effectiveness of eteplirsen in treating exon-51-based DMD which accounts for 13% of all cases.

Talk the talk
On the flipside in the DMD space, Prosensa (NASDAQ: RNA) also saw its shares rocket higher on the week, but this was merely because of commentary made by the company that its DMD drug, drisapersen, which failed miserably in a phase 3 trial, may still offer a clinical benefit. According to Prosensa, a closer examination of the data suggests that earlier patient treatment, and longer treatment duration, could delay disease progression. Prosensa intends to consult with clinical experts and regulators to determine the next step for drisapersen. I wouldn't get too excited, though, with GlaxoSmithKline backing out of its drug development pact with Prosensa and little more than word-of-mouth evidence supporting drisapersen's future development.

Forward, march!
The data was a bit mixed after the bell on Thursday for clinical-stage biopharmaceutical company ArQule (NASDAQ:ARQL) after it reported results for tivantinib in two separate studies. In its METIV-HCC hepatocellular carcinoma trial, the data monitoring committee gave the company a go-ahead to proceed to phase 3 trials after recommending the company lower its dosing to 120 mg from 240 mg. With regard to its ATTENTION trial for metastatic non-squamous non-small-cell lung cancer in Japan, the combination of tivantinib with erlotinib provided a benefit of 1.7 months in median overall survival (12.9 months versus 11.2 months) compared to the erlotinib-only arm, but this benefit is not considered statistically significant. In other words, ArQule's liver cancer trial is moving forward, and the safety profile of tivantinib could be vastly improved, with a lower dosage in liver cancer while its NSCLC future remains uncertain at best.

Not so fast ...
Following last week's 545% romp higher, Intercept Pharmaceuticals (NASDAQ:ICPT) shares cooled this week, losing more than $200 per share at one point, after new data for its nonalcoholic steathohepatitis drug, obeticholic acid, or OCA, concluded that cholesterol levels in patients, specifically the bad type of cholesterol, had risen during treatment and would require further investigation. Furthermore, Intercept's CEO, Mark Pruzanski, noted that it may need the help of a larger pharmaceutical partner to bring OCA to market. These clouds of uncertainty definitely took the sails out of Intercept's huge gains but still leaves the company with a better than $220 gain per share in just the past seven sessions.

Early stage success
Finally, late in the week, clinical-stage anti-cancer stem cell drug developer OncoMed Pharmaceuticals (NASDAQ:OMED) reported positive early results for its lead drug demcizumab and OMP-59R5 as possible treatments for advanced pancreatic cancer at the 2014 Gastrointestinal Cancers Symposium. In both studies, which combined either demcizumab or OMP-59R5 with Eli Lilly's Gemzar and Celgene's Abraxane, the combination of drugs was well tolerated. In the demcizumab trial, a RECIST partial response was noted in three out of six patients with stable disease exhibited by two others, for a clinical benefit rate of 83%. In the OMP-59R5 trial, this combination produced six RECIST partial responses as well as three stable disease patients. Both studies will be moving to phase 2 trials later this year. 

In Part 2 of "This Week in Biotech" we'll take a closer look at the three FDA actions and lone collaboration which set the stage for some of this week's biggest moves.