Just how big is the biosimilars business going to be in 5 years?

Thomson Reuters BioWorld took a deep dive into the subject and surfaced today with a detailed report outlining a bustling new global business with roughly 700 so-called follow-ons put in the clinic by 245 companies and institutions. Looking ahead to 2020, analysts say, you can anticipate that biosimilars will account for about $25 billion out of $100 billion in sales for off-patent biologics.

The EU was the first to outline a regulatory pathway for biosimilars, and it's been seeing the largest number of approvals. Drugmakers in India and Korea, meanwhile, have clearly outlined a big role for themselves in delivering less expensive biosimilars to the developing world, where people often find themselves unable to afford biologics at branded prices. And while the U.S. is just now opening the door to biosimilars, Thomson Reuters BioWorld concludes that dozens of meetings have occurred at the FDA with developers racing to penetrate the world's biggest drug market.

In some respects, the report echoes many earlier estimates for biosimilars, such as an expected 20% to 30% discount off the price. But it also offers a richly detailed look at how manufacturers plan to fight back, often quite effectively by offering similar discounts on their aging products. And the lead developers in the space, meanwhile, are working up some ambitious grassroots marketing campaigns aimed directly at physicians and payers as they go toe-to-toe with the originators.

"We're going to have to communicate," Richard Davies, Hospira's ($HSP) senior vice president and chief commercial officer, tells Thomson Reuters.

This battle is just about to begin in the U.S., but a number of big players ranging from the likes of Sandoz to Eli Lilly ($LLY) are preparing to throw their weight behind the first wave of biosimilars set to crash the market. -- John Carroll, editor-in-chief (email | Twitter)