With the SPDR S&P Biotech Index up 43% 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.

It was a bit unusual this past week, with most of the data in the biotech sector trickling out under the radar with investors effectively taking the week the off. Still, there were five important events worth examining.

USPTO, FDA, and EMA -- oh, my!
Governing body actions were a big reason for applause this week, at least among the following three companies.

Small-cap biopharmaceutical company Immunomedics (IMMU), for example, gained 19% on the week after announcing that it had been granted two patents -- one for its antibody-drug SN-38 conjugates, and the other for the methods and compositions of labeling peptides and other molecules utilizing F-18 -- from the U.S. Patent and Trademark Office. The key point here is that Immunomedics' antibody-drug conjugate platform, which uses its proprietary technology to attach a toxin onto an antibody and deliver that toxin directly to a cancer cell, will be protected from competition. Furthermore, it frees Immunomedics up to forge partnerships if its two ongoing mid-stage clinical trials turn out favorably this year.

Small-cap Cell Therapeutics (CTIC) was a big beneficiary from the Food and Drug Administration this week, with the company on Thursday announcing that the partial clinical hold on experimental cancer drug tosedostat had been removed. The hold was initially put in place in June after a patient in one of Cell Therapeutics' trials had died. The removal allows CTI to continue its two mid-stage studies of the drug, which is an inhibitor of aminopeptidases, which are required for tumor cell growth. This is definitely a short-term victory for CTI shareholders, but I'm still not convinced that the company is a viable investment here given its shaky history of diluting shareholders.

Finally, crossing the pond to our friends over in Europe, NPS Pharmaceuticals (NASDAQ: NPSP) on Friday received an orphan drug designation for naptara, a "bioengineered replacement for endogenous parathyroid hormone as a treatment for hypoparathyroidism" from the European Medicines Agency. In addition to treating a rare disease which should give NPS significant pricing power, the orphan drug status protects NPS's drug from biosimilars for a period of 10 years and could reduce its fees for marketing approval. In other words, just chalk this up as another victory for NPS.

Clinically impressive
There wasn't much clinical data to sift through during this holiday shortened week (and with good reason... who releases clinical data between Christmas and New Year's?), but Amgen's (AMGN 2.35%) and UCB's joint mid-stage study evaluating romosozumab as a treatment in postmenopausal women with low bone mineral density that was released on Wednesday is certainly worth noting. The results, which were published in the New England Journal of Medicine, notes that patients treated with romosozumab for 12 months demonstrated increased bone mineral density at the lumbar spine, total hip, and femoral neck relative to the placebo. The study also points to increases in bone mineral density in exploratory analyses in the lumbar spine and hip when compared to currently approved treatments Fosamax and Forteo. I'll be curious how romosozumab fares in a larger phase 3 study, but for now I like what I'm seeing.

Sent packing
But, as usual, it wasn't a perfect week ... just ask shareholders of Sanofi (SNY 2.00%) which saw the company's multiple sclerosis drug, Lemtrada, get rejected by the Food and Drug Administration. As noted by my Foolish colleague and biotech guru Brian Orelli, Sanofi didn't blind the two drugs being tested -- Lemtrada and Pfizer and EMD Serono's Rebif -- in trials, which led to the possibility of patient biases. In other words, Sanofi is going to be required to run an addition trial with Lemtrada (a blinded one this time) if it has any home of getting this MS treatment approved. While I still believe an approval is likely, we're probably looking at another year before this winds up in front of the FDA again.