A scientist works in a lab at Thousand Oaks-based Amgen. (Courtesy photo)

The U.S. Food and Drug Administration today approved its first-ever biosimilar, a drug known as Zarxio that mimics Amgen’s chemotherapy drug Neupogen, placing the Thousand Oaks-based biotech giant under peaked pressure to bring new treatments to market.

In contrast to the abundance of American consumers’ pill medication options, biologic drugs had until now been protected from competition. Zarxio, the first biopharmaceutical copycat approved in the U.S., was brought to market by Novartis’ generics unit, Sandoz, and will pave the way for lower-cost alternatives to existing treatments.

The FDA had previously preempted biosimilar competition while it decided how to treat reproductions of biologic drugs, which are produced from living cells or tissue and thus impossible to truly replicate.

Amgen’s Neupogen brought in $5.8 billion of the firm’s $18.1 billion in product sales for 2013, the year in which the company’s patent on it expired. Last year, it accounted for only $1.2 billion of that total.

Meanwhile, Amgen’s competitors are already seeking approval for alternatives to at least three other drugs in the company’s portfolio. Sandoz has submitted applications for knockoffs of Neulasta and Enbrel, while Lake Forest-based Hospira has applied for a biosimilar to Epogen.