With August winding down, summer won't be around much longer. Several health-care stocks still had hot days this past week, though. Here are three of the hottest in the market.

Pharmaceutical phoenix
Like the mythicial phoenix, Progenics Pharmaceuticals (PGNX) could be rising from the ashes. Shares soared by 16% this week.

It was only a little over a year ago when Progenics and partner Salix Pharmaceuticals (NASDAQ: SLXP) received the news that the Food and Drug Administration wouldn't approve Relistor as a treatment of opioid-induced constipation in adult patients with chronic pain not caused by cancer. That rejection caused Progenics shares to immediately lose around half their value. The stock continued to fall over the next few months.

Progenics and Salix announced in June that an FDA advisory committee would again review Relistor's supplement New Drug Application, or sNDA, after Salix appealed the initial complete response letter received in 2012. Since June, Progenics shares have had an up-and-down ride. There wasn't any big news over the last week to propel the stock, but it's clearly on one of the up stretches of that ride.

Trial balloon
Shares of Astex Pharmaceuticals (NASDAQ: ASTX) went up like a hot-air balloon this week on positive clinical trial results. The stock climbed 11%. Astex announced top-line results on Wednesday from an ongoing phase 2 study of experimental drug SGI-110 in treating acute myeloid leukemia, or AML. These results indicated an overall complete remission rate of 25%. The market clearly liked what it heard, with Astex shares jumping as much as 26% in intraday trading before settling down a bit.

This has proved to be a good year for Astex so far. The stock is up a whopping 136% year to date. Continued sales strength for myelodysplastic syndromes drug Dacogen combined with solid progression in the pipeline have made Astex one of 2013's big winners.

Inside straight
Shareholders of Halozyme Therapeutics (HALO 1.14%) have seen their account balances go up in nearly a straight line since mid-August. This past week was no exception, with Halozyme shares climbing 11%.

These nice gains have been propelled in large part by insider purchases. Kathryn Falberg, a director with Halozyme, bought 100,000 shares in August. It's usually encouraging to outside investors to see insiders scooping up a large number of shares on the open market.

Halozyme has a few upcoming catalysts that hold the potential to make these insider purchases pay off in a short time frame. European approval for Roche's Herceptin using Halozyme's recombinant human hyaluronidase, or rHuPH20, is expected soon. Baxter (BAX -0.47%), Halozyme's partner on HyQvia, expects to submit additional data to the FDA later this year to address questions raised in the complete response letter it received in 2012.

Looking good
All three of these stocks have looked pretty good lately. If the FDA advisory committee gives a thumbs-up on Relistor, Progenics could see the biggest upside through the end of the year. That's not a given, though.

Astex has a solid pipeline and good revenue coming in from Dacogen. Company management says next year could be tougher, with anticipated lower Dacogen sales in the U.S. Over the long run, Astex should do well.

Multiple possible catalysts could send Halozyme even higher in the months ahead. I like that the small company has strong partnerships with several larger companies.

There's no guarantee that any of this week's humongous health-care stocks will continue to sizzle like they have recently. However, my view is that investors who aren't afraid of taking on risk should take a look at any or all of them. Hot stocks can sometimes get even hotter.