Circumstantially sufficient

FDA convened last week's meeting of its Cardiovascular and Renal Drugs Advisory Committee after the three companies that market phosphate binders to treat hyperphosphatemia in dialysis patients asked for guidance on extending the labels of the products to advanced chronic kidney disease patients not yet on dialysis. But if the companies were hoping for clarity, what they got instead was a mixed message that sounded a bit like "do as I do, not as I say."

The committee rejected the sponsors' contention that there is sufficient evidence to consider reduction in phosphate levels a validated surrogate marker of clinical benefit. On the other hand, the panel felt that there were enough data of other sorts - epidemiological and observational - and a sufficiently strong biological rationale to allow the label extension...