A new era of immuno-oncology has arrived

After years of posting impressive clinical results and pushing analyst projections to greater and greater heights, a new class of cancer treatments has finally made its way onto the market, opening up what's expected to become a multibillion-dollar industry.

Leading the way are so-called checkpoint inhibitors, antibodies that unblind the immune system to previously unseen tumors, helping the body's own T cells vanquish cancerous growth. Merck ($MRK) won the first-ever FDA approval for such a treatment with its Keytruda, and Bristol-Myers Squibb ($BMY) followed closely on its heels with Opdivo.

Behind them are Roche ($RHHBY) and AstraZeneca ($AZN), at work on similar antibodies, and analysts expect the whole class of therapies to bring in roughly $35 billion a year at its peak. Melanoma is the group's first target, but each contender is carrying out combination studies designed to determine how well PD-1- and PD-L1-blocking therapies can work in tandem with other oncology treatments.

Outside the checkpoint club, Amgen ($AMGN) picked up a lightning-fast approval for its blinatumomab, an immunotherapy targeting blood cancer. The antibody, marketed as Blincyto, is a product of Amgen's bispecific T cell engager (BiTE) system, designed to direct the body's disease-fighting immune cells to attack cancerous growth. It works by connecting CD19, a protein commonly found on cancer cells, to CD3, which is expressed by the immune system's T cells, and Blincyto's approval marks the first nod for any CD19-targeting agent, a class that includes promising immunotherapies from Novartis ($NVS), Juno Therapeutics ($JUNO), Kite Pharma ($KITE) and others.

And the agency's pledge to hurry along new treatments that could change the standard of care has encouraged a host of developers at work on further-from-the-market treatments. For example, Pfizer ($PFE)--whose now-spoiled effort to buy AstraZeneca was driven in part by immuno-oncological envy--has spent big to shoulder into the space on its own terms, signing deals with Merck KGaA and iTeos Therapeutics that could top out at nearly $3 billion combined.

Smaller outfits are mapping out the promise of immuno-oncology, as well, including 2014 Fierce 15 winners Adaptimmune, Sutro Biopharma and Aduro BioTech; billionaire Patrick Soon-Shiong's NantWorks; and many more. -- Damian Garde