While the overall market muddled through the past five days, some stocks were on fire. Here are three health-care stocks experiencing humongous gains over the past week.

Jumping over Jakafi
Incyte (INCY -0.89%) takes the top spot on our humongous health-care stocks list. Shares jumped 30% for the week after the company announced good news from a clinical study of Jakafi in treating pancreatic cancer.

Results from the mid-stage study showed a six-month survival rate of 42% for patients taking Jakafi along with the chemotherapy capecitabine. For the group of patients taking placebo with the chemotherapy, the six-month survival rate was only 11%. Incyte also reported that Jakafi was generally well tolerated during the study.

Novartis (NVS 1.93%) also emerges as a potential winner with the latest results. The Swiss drugmaker markets Jakafi outside the U.S. under the brand name Jakavi as a treatment for myelofibrosis. Incyte maintains U.S. rights for the drug.

Rising expectations
Unlike Incyte, Pacific Biosciences of California (PACB 6.16%) didn't have any big news to announce this week. It didn't need any, though. Shares still climbed more than 23%.

The good news for PacBio came a couple of weeks ago with its second-quarter results. While not exactly awe-inspiring, the numbers convinced some analysts that the biotech had turned the corner. In its upgrade of the stock from "underweight" to "neutral," Piper Jaffray noted "increased stability" for Pacific Biosciences.

Since those second-quarter figures were announced, PacBio's shares have steadily risen. The company, which sells genetic sequencing systems, had a very rough 2012 -- losing nearly 80% of its value at one point. This year has been much better, with shares more than doubling so far in 2013.

Putting it well
There wasn't any real news this week for Astex Pharmaceuticals (NASDAQ: ASTX), either. But that didn't stop shares from moving up by 18%.

Astex reported good second-quarter performance on Aug. 1 with better-than-expected sales of Dacogen, which treats anemia in patients with myelodysplastic syndromes. The stock responded positively, but those results weren't enough to sustain positive momentum for the stock. Within a week, shares were at or below previous levels.

At this point, it's not really clear why Astex experienced such a good week. However, at least one person is betting big that the stock continues to perform relatively well. On Tuesday, an unknown trader sold 5,000 put options for Astex stock expiring in September with a strike price of $5. If Astex drops to $5 per share or below by Sept. 20, this person would have to buy half a million shares.

Looking ahead
It's quite possible that these three stocks might not enjoy humongous performance for too much longer. Astex warned that 2014 could present a more challenging environment with lower expected sales of Dacogen. My colleague Sean Williams suspects that PacBio's stock might have surged too much considering its business realities. Incyte could easily drift back down some as well. The pancreatic cancer study results were great, but there's still phase 3 to get past.

Overall, I like Incyte the most of this week's top performers. Jakafi is already racking up solid sales and shows excellent potential for expanding beyond its currently approved indication. I also think there's a decent chance that a larger player could have Incyte on its acquisition radar screen at some point. There could be plenty of ups and downs along the way, but this biotech could be one for investors to keep on their radar screens as well.