ET is reporting some sad news about Hollywood legend Merv Griffin -- who's being treated for a second bout of prostate cancer.

Sources now tell ET the prognosis isn't looking good, but his reps won't confirm or deny.

It was revealed in late July that the beloved TV icon was suffering from a recurrence of prostate cancer.

At that time Merv asked for his well-wishers, in lieu of sending him flowers, to donate to the Young Musicians Foundation, which he chairs.

Griffin is the creator and producer of the popular game shows "Jeopardy!" and "Wheel of Fortune."