(Bloomberg) — The burgeoning field of cancer immunotherapy is showing great promise with previously hard-to-treat forms of the disease. Now comes the next hurdle: figuring out which patients best respond to the drugs.
At stake is billions of dollars in potential revenue for companies including AstraZeneca P.L.C. (NYSE:AZN), Roche Holding A.G., Bristol-Myers Squibb Co. (NYSE:BMY) and Merck & Co. (NYSE:MRK) The drugmakers are racing to develop medications that harness the body’s own immune system to fight various forms of cancer.
The drugs show the most pronounced responses in patients whose tumors have high levels of a protein known as PD-L1. But each company is currently using its own, slightly different test of PD-L1 levels in patient trials, making it hard to compare one drug against the other.
See also: Cost to develop a drug more than doubles.
And none of the tests is good enough yet to rule out patients who won’t respond to the drugs, creating a conundrum about how to use them, according to experts at the annual American Society of Clinical Oncology meeting, which started Friday in Chicago and continues Monday.
The lack of a standard test for telling who should get the new drugs “is one of the big problems” in the immune therapy field, said Richard Pazdur, the top cancer drug official at the U.S. Food and Drug Administration.
Merck and Bristol-Myers are working with Dako, a division of Agilent Technologies Inc. (NYSE:A), on two different tests. Roche and AstraZeneca are collaborating with Ventana Medical Systems Inc., a division of Roche, on their separate diagnostics.
Roche, whose drug MPDL3280A doubled the survival rate of lung cancer patients in trial data presented in Chicago, rose 2.4 percent to 282.80 Swiss francs as of 10:09 a.m. in Zurich. Astra, whose PD-L1 inhibitor MEDI4736 reduced lung tumors in 27 percent of patients in an early-stage trial, climbed 1.9 percent in London.
Amid the successes with experimental medicines, the FDA is trying to push companies to work together on tests, though it has no authority to force them to, Pazdur said.
Devising reliable tests is crucial because the drugs are very expensive, with two of the first to hit the market — Opdivo from Bristol-Myers and Keytruda from Merck — costing about $150,000 a year. And because immune drugs are associated with side effects ranging from lung inflammation and hepatitis to rash and diarrhea, doctors don’t want to use them on patients who aren’t going to be helped.