UPDATE 2-US FDA warns of fetal risk of two transplant drugs

(Adds FDA, Novartis comments, detail from Roche)

WASHINGTON, May 16 (Reuters) - U.S. health officials issued an alert on Friday about the risk of first-trimester miscarriages and birth defects from Novartis AG (NOVN.VX) (NVS.N) and Roche Holding AG (ROG.VX) transplant drugs.

A strong warning about those risks was added to the labels of Roche's CellCept and Novartis' Myfortic in November.

The new alert was meant, in part, to grab the attention of doctors who prescribe the drugs for unapproved uses such as treating lupus, said Food and Drug Administration spokesman Christopher Kelly.

The FDA alert also was issued as a reminder to doctors who prescribe the immune-suppressing drugs for the approved use of preventing rejection of transplanted organs, Kelly said.

Roche spokesman Christopher Vancheri said the company had sent a letter to doctors when the "black box" warning, the strongest type for prescription drugs, was added last year.

The FDA's Kelly said some physicians who prescribe the drugs for unapproved uses may not have noticed the labeling change or the letter from manufacturers.

Reported birth defects included cleft lip and palate, and ear deformities, the FDA said.

Data from a U.S. pregnancy registry showed 15 miscarriages and four birth defects among 33 pregnancies with exposure to CellCept, Vancheri said. Data is reported voluntarily so the rates of problems cannot be precisely calculated.

Also, because many transplant patients take a combination of immune-supressing drugs, "it is not possible to determine whether causality or not can be attributed to CellCept," Vancheri added.

Novartis spokeswoman Amy Hunter said the company had not received any reports of birth defects associated with Myfortic, known generically as mycophenolic acid, at the time of the label change in November.

The drugmaker added the warning, however, at the FDA's request, she said. Myfortic is chemically similar to CellCept, known generically as mycophenolate mofetil.

In April, the FDA said it was investigating if CellCept and Myfortic may trigger a potentially fatal brain disorder called progressive multifocal leukoencephalopathy. That review is ongoing. (Reporting by Lisa Richwine; editing by Dave Zimmerman and Tim Dobbyn)