Drug companies and a contract research organization are urging the FDA to sharpen its recommendations on how to reveal to blood cancer patients whether they’re taking placebos or the real thing in clinical trials.

The agency in August issued draft guidance suggesting that blood cancer patients be told if they’re taking experimental drugs or placebos if their disease comes back or worsens. It also said sponsors should alert patients and researchers if they’re worried meds are causing bad reactions.

In comments, major drug companies asked the FDA to clearly state how it wants sponsors to “un-blind” the information.