With the SPDR S&P Biotech Index up 57% 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.

Overall there were seven key events that biotech-savvy investors should be aware of: two regulatory actions, four clinical updates, and the announcement of a collaboration.

Striking the gavel
Regulatory dealings this week brought wildly mixed reactions for Endocyte (NASDAQ: ECYT) and Geron (NASDAQ:GERN).

Endocyte shares skyrocketed 92% on Friday after receiving two pieces of positive news headlined by a favorable view of Vynfinti (the EU brand name for vintafolide) by the Committee for Medicinal Products for Human Use in Europe, or CHMP, for use in patients with platinum-resistant ovarian cancer. The CHMP issued a positive opinion for conditional marketing authorization of Vynfinti as well as its companion imaging components Folcepri and Neocepri. These three products will now move onto being reviewed by the European Commission for potential approval which would be a big positive for Endocyte as well as its ex-U.S. licensing partner Merck.

And just to add icing on the cake, Endocyte also reported that a phase 2b study known as TARGET involving the combination of vintafolide and docetaxel in the U.S. for non-small-cell lung cancer, or NSCLC, patients met its primary endpoint by reducing the risk of disease progression and death by 25% relative to taking docetaxel by itself. 

Geron, however, had a completely different experience with the Food and Drug Administration this week. On Thursday the company noted in a press release that those patients receiving a clinical benefit from experimental drug imetelstat may continue to receive it in an investigator-sponsored myelofibrosis trial being run by the Mayo Clinic, but that no new patients could be enrolled under a new partial clinical hold. This move is in addition to the full clinical hold that the FDA has exerted over Geron's internal studies of the drug until a review of the reversibility of liver abnormalities observed in studies can be ascertained. It doesn't look like things are going to get any easier for Geron over the next few weeks, but as I discussed earlier this week, all hope for imetelstat isn't lost.

It's all in the numbers
Clinical data from four separate companies this week was also just as mixed as the aforementioned regulatory events.

In the plus column, Amgen's (NASDAQ:AMGN) experimental homozygous familial hypercholesterolemia therapy, known as evolocumab, met its primary endpoint of a clinically meaningful and statistically significant reduction in LDL-cholesterol from baseline by week 12 in the first part of its phase 2/3 TESLA trial. Evolocumab is unique in that it could be administered far less frequently than the two currently FDA-approved treatments and appears to have a much more favorable safety profile. To add, because evolocumab is being tested on a number of additional indications, its price point may also be significantly lower than its competitors. All told, this could be shaping up to be a monster drug for Amgen.

Joining Amgen in the cheering section was Synta Pharmaceuticals (NASDAQ: SNTA) which announced positive interim results from its ENCHANT-1 study involving ganetespib that targets metastatic breast cancer at the European Breast Cancer Conference. The study was designed to measure ganetespib's efficacy across three trial cohorts which included HER2-positive (HER2+) and triple-negative breast cancer patients over a 12-week period. As of week three, six of seven HER2+ patients achieved a metabolic response with 18 of 31 TNBC patients demonstrating a metabolic response. At week six, when RECIST responses can first be established, two HER2+ patients demonstrated an objective response, or OR, with four stable disease while the TNBC cohort has 2 OR's, 11 stable disease, and 13 disease progressions. It also noted that one HER2+ patient had a complete OR and was still on the therapy after more than 10 months.

Things weren't so cut-and-dried for Intercept Pharmaceuticals (NASDAQ:ICPT) which on Monday attempted to drown investors in data including an earnings report, a positive phase 3 trial involving obeticholic acid, or OCA, as a treatment for biliary cirrhosis of the liver, and an updated adverse event profile within its 10-K annual filing on OCA for its nonalcoholic steatohepatitis, or NASH, study. The earnings report and phase 3 POISE trial delivered good news. Data from the POISE trial demonstrated a primary endpoint response of 47% and 46% across the two dosage groups for OCA compared to just 10% for the placebo.

The bigger news, though, was buried in its 10-K that 10 cardiovascular events had occurred in seven patients (2.5% of the patient population) across both treatment groups in its FLINT trial for NASH. However, the National Institute of Diabetes and Digestive and Kidney Diseases, or NIDKK, concluded that the number of cardiovascular events was not statistically different than the number of cardiovascular events in the placebo group. In only two patients did the NIDKK even allude that OCA was possibly related to their adverse event. Yet, what we saw this week is that given Intercept's huge run higher this year even the slightest imperfection could remove the luster from this stock quickly.

The news was even worse for Agenus (NASDAQ:AGEN) when partner GlaxoSmithKline announced that its phase 3 MAGE-A3 cancer immunotherapeutic trial involving Agenus QS-21 adjuvant didn't meet either of its first two co-primary endpoints in NSCLC. The good news is that Glaxo is continuing its study toward a third co-primary endpoint which is geared toward a specific group of patients that it believes will benefit most from the therapy. Data for this study isn't due out until sometime next year. Thankfully, Agenus has a deep pipeline and a number of ongoing studies, but this initial failure has to be unsettling for existing shareholders.

Double your pleasure, double your fun!
Finally, on Monday Five Prime Therapeutics (NASDAQ:FPRX) and Bristol-Myers Squibb decided to put their heads together and formed a collaborative alliance. Under the terms of the deal, Bristol-Myers will get access to Five Prime's immuno-oncology platform which puts Bristol-Myers in the driver's seat of what does and doesn't get developed and gives it the opportunity to retain full worldwide rights to these collaboratively developed therapies. In return, Five Prime gets a $20 million upfront payment from Bristol-Myers, is eligible to receive $9.5 million in researching funding over the term of their deal, and will get a $21 million common equity investment (nearly 5% of outstanding shares) from Bristol-Myers. All told it looks like a pretty inexpensive way for Bristol-Myers to further dip its toes into the immunotherapy market and for Five Prime to net some quick cash and a proven partner.

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.