With the SPDR S&P Biotech Index up 22% 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.

Gilead brings the brooms
Get out your brooms, because no company cleaned up this week when it comes to positive data more than Gilead Sciences (NASDAQ:GILD). On Wednesday, the U.S. Food and Drug Administration announced that it had approved oral Zydelig (formerly idelalisib) to treat three B-cell blood cancers, including relapsed chronic lymphocytic leukemia, follicular lymphoma, and small lymphocytic lymphoma. As noted in Gilead's press release, accelerated approval was granted for follicular lymphoma and small lymphocytic lymphoma based on overall response rate. In treating relapsed chronic lymphocytic leukemia patients, for example, Zydelig led to an 82% reduction in risk of disease progression or death when combined with Rituxan, compared with the control arm of just Rituxan alone.

Were that not enough, on Friday the Committee for Medicinal Products for Human Use in Europe (essentially Europe's equivalent of the FDA panel) took a positive view on Zydelig for the treatment of chronic lymphocytic leukemia and follicular lymphoma, potentially clearing the way for an eventual approval in Europe.

And, as icing on the cake, Gilead delivered its second-quarter earnings results on Wednesday and blew Wall Street's estimates out of the water with total revenue of $6.5 billion, compared with $2.8 billion last year, as sales of hepatitis C wonder drug Sovaldi jumped to $3.48 billion. If you aren't keeping a close eye on Gilead, you're doing yourself a disservice.

Feeling Sage
Following a successful IPO just over a week ago, Sage Therapeutics (NASDAQ:SAGE) saw its shareholders receive fantastic news this past Tuesday after the FDA granted fast-track designation for its lead drug, SAGE-547, which is aimed at treating super-refractory status epilepticus, a rare seizure condition for which there is no current therapy approved. Having fast-track designation gives Sage Therapeutics more interaction with the FDA and a potentially shorter review period, and it could give the drug accelerated approval, which is great considering there are no alternatives currently for these patients. Sage specifically notes that there are approximately 150,000 cases of status epilepticus in the U.S. each year.

On the investable side of the coin, investors may also want to take into account that Sage is still lugging around a $660 million valuation and has only one compound out of preclinical studies. While this is a welcome designation, Sage may still have a lot to prove to Wall Street to maintain its valuation.

Source: Thetaxhaven, Flickr.

Puma takes off
The puma may not be the quickest land animal, but you'd get quite the disagreement from biotech investors this week, after Puma Biotechnology (NASDAQ:PBYI) more than tripled at one point after it announced positive top-line results from its phase 3 study involving PB272, also known as neratinib, as an extended adjuvant treatment for breast cancer.

In the company's ExteNET study, which included more than 2,800 early stage HER2-positive breast cancer patients who had undergone surgery and a year of adjuvant treatment with Herceptin, the treatment group that received neratinib in their extended adjuvant treatment demonstrated a 33% improvement in disease-free survival versus the control group -- a statistically significant difference. The secondary endpoint, which was disease-free survival including ductal carcinoma in situ compared with the placebo, also produced a statistically significant 37% improvement in the neratinib arm. Puma plans to release the full results of its study in a future scientific meetings, but it is on course to apply for approval for neratinib in the first half of 2015.

Source: Daniel Paquet, Flickr.

Inovio hits the target
Cancer immunotherapy company Inovio Pharmaceuticals (NASDAQ:INO) hit the bull's-eye this week, much to the chagrin of shareholders, as it reported positive results from its phase 2 study involving VGX-3100 in women with cervical dysplasia associated with human papillomavirus types 16 or 18. As Inovio points out in its release: "Treatment with VGX-3100, Inovio's HPV16/18-specific immunotherapy, resulted in histopathological regression of CIN2/3 to CIN1 or no disease, meeting the study's primary endpoint. In addition, the trial demonstrated clearance of HPV in conjunction with regression of cervical lesions. Robust T-cell activity was detected in subjects who received VGX-3100 compared to those who received placebo."

By the numbers, Inovio's data showed that 49.5% of women saw their cervical intraepithelial neoplasia 2/3 (CIN2/3) regress into CIN1 or no disease, compared with just 30.6% of control arm patients. The treatment was generally well tolerated; however, redness at the site treatment was more pronounced in the VGX-3100 arm. There's a large opportunity for non-surgical cancer-fighting drugs to shine, and Inovio is certainly making its case that it belongs among the lead contenders.

TG's promising early double dose of good news
Finally, on Tuesday, clinical-stage biopharmaceutical company TG Therapeutics (NASDAQ:TGTX) announced preliminary results from its phase 1 studies involving the combination of TG-1101 and TGR-1202 for chronic lymphocytic leukemia, or CLL, and other aggressive lymphomas.

According to TG Therapeutics' data, four out of the first five evaluable patients with CLL, or small lymphocytic leukemia, achieved a partial response at their first assessment, while the final patient responded with a 44% nodal reduction. However, all five patients exhibited a reduction of 50% or greater in absolute lymphocyte count, with TG noting that the combo appeared to be safe and well tolerated by patients.

As I covered on Tuesday, TG's second study involving this combo in non-Hodgkin's lymphoma patients or patients with Richter's syndrome delivered stable disease or signs of improvement in 90% of evaluable patients.

This is a really positive early result for TG Therapeutics, but investors should also keep in mind that we're merely looking at phase 1 results that often tend to focus more on safety and interactions than on efficacy (even though we did receive some efficacy data here). I would probably hold off on calling this combo a success until we get a much larger patient pool to base a decision on.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.