With the SPDR S&P Biotech Index up 21% 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.

If you're currently holed up in your home on the East Coast because of winter storm Nemo, or mired under a West Coast rain storm, I have nothing but bright news for you this week as we'll be highlighted two FDA drug approvals, a positive mid-stage clinical result, a blockbuster deal in the multiple sclerosis sector, and the potential for another deal involving a large pharmaceutical company.

On the FDA approval front, Hyperion Therapeutics (NASDAQ: HPTX) sneaked a late-day approval of urea cycle disorder drug Ravicti in last Friday. The FDA had originally postponed the PDUFA date of Jan. 23 a full three months, as it was purportedly working with Hyperion on labeling and post-marketing requirements. It took the FDA only a week and a few days beyond its original PDUFA date to approve Ravicti. This is Hyperion's first FDA-approved drug, and it is expected to be commercially available by the end of April. Moreover, the patent allowance on the drug was extended all the way until 2032.

The biotech equivalent of Superman since the year began, Celgene (CELG), notched another victory on its belt when the FDA approved its multiple myeloma drug, Pomalyst, yesterday. Pomalyst is given as a secondary line of treatment following at least two other cancer therapies and was approved based on response rate alone, not on survival rate, which has yet to be verified. In trials, 29.2% of patients achieved a partial response or better, compared with just 7.4% for the control arm. Now, Pomalyst will go head-to-head with Onyx Pharmaceuticals' recently approved Kyprolis in a still relatively young blood cancer treatment market. 

Also on Friday, Oncolytics Biotech (ONCY -1.89%) reported stellar phase 2 results for its squamous cell carcinoma of the lung drug, Reolysin. The drug was tested on 20 evaluable patients in midstage trials that either previously had squamous cell carcinoma, or had it metastasize on them. Based on the results, 95% --19 of 20 -- showed tumor shrinkage, with the average reduction in size being about one-third. Secondary endpoints of the study, including progression-free survival, appear intriguing as well, with the data noting nine partial responses, nine with stable disease, and three with progressive disease.

Biogen Idec (BIIB -0.14%) made waves earlier this week, when it broke out its wallet to fork over $3.25 billion to Elan to gain full rights to multiple sclerosis wonder drug Tysabri. Currently, Biogen and Elan share revenue on Tysabri down the middle, but the $3.25 billion will allow Elan to focus on researching its next therapies while giving Biogen full rein over Tysabri sales going forward. All told, it's probably a better deal for Biogen over the long term, and unsurprisingly, the company received a timely upgrade from Citigroup early Friday morning to "buy" from "neutral," with a $187 price target.

Finally, Protalix BioTherapeutics' (PLX 2.61%) shares surged earlier in the week after confirming reports that it's hired Citigroup to help with its strategic review. Israeli-based website Calcalist also posted that Pfizer has shown interest in purchasing Protalix -- which would make sense, since they jointly developed Elelyso, an FDA-approved Gaucher disease drug -- but it won't pay the premium that Protalix is requesting. Understandably, with orphan drugs carrying such large price tags, Pfizer needs to be careful not to overpay for Protalix, especially if physicians and patients resist the hefty price tag.