NEW YORK ( The Deal) -- As the saying goes, to every thing there is a season. And this is the season for biotechnology initial public offerings.OncoMed Pharmaceuticals is a perfect case in point. The Redwood City, Calif.-based company's shares began trading at $17 on Thursday under the ticker symbol OMED and ended the day at $27.01, up $10.01 and 59% on the day. That's in line with the two most successful recent IPOs for biotech companies, bluebird bio (BLUE) and Epizyme ( EPZM), which ended their first trading days up around 60% and 50%, respectively. If OncoMed is lucky, it will follow in the footsteps of those two companies. Bluebird ended trading Thursday at $34.67, double its $17 starting price. Epizyme, which started trading May 31 at $15, has nearly tripled its value, ending Thursday at $42.72. OncoMed priced at $17 a share on Wednesday, with a plan to sell 4.8 million shares of stock to the public. That was an increase from its original estimated price range of $14 to $16 a share. In addition, the company granted the underwriters a 30-day option to purchase an additional 720,000 shares. The company is developing antibodies and other protein-based drugs to target cancer stem cells, or CSCs. The drugs work in biologic pathways critical for the survival of what are called tumor-initiating cells. Those cells are responsible for the characteristic speedy growth rate and tricky differentiating properties of tumors -- exactly what makes cancer cells so hard to kill. OncoMed isolates and monitors those cells using specific surface markers and flow cytometry to find and develop targets associated with key biologic pathways in stem cell biology and cancer. The company began operating in 2004 and is backed by venture capitalists including U.S. Venture Partners and Latterel Venture Partners. It has two major collaboration agreements, with Bayer Schering Pharma ( BAYRY) and GlaxoSmithKline ( GSK). The Glaxo deal, which could be worth about $730 million, is to develop novel product candidates targeting CSCs via Notch pathway signaling modulation. OncoMed's Anti-Notch2/3 is now in a Phase 1B/2 trial in nonsmall cell lung cancer and pancreatic cancer and Anti-Notch1 is in Phase 1 for multiple tumor types.