(CNN) — The US Food and Drug Administration’s longtime oncology chief has filed to retire from the agency just weeks after he was chosen to lead the FDA’s drug division, according to four people familiar with his decision.

Dr. Richard Pazdur was named director of the Center for Drug Evaluation and Research on November 11, taking leadership of the FDA’s largest division after its former director, Dr. George Tidmarsh, abruptly resigned .

Pazdur’s decision was first reported by Stat News .

It represents a remarkable reversal from just weeks ago, when FDA Commissioner Dr. Marty Makary announced his appointment in a laudatory statement that described him as a “true regulatory innovator” and “an impressive forward-thinking scientist.”

Both Makary and and Dr. Vinay Prasad, chief of the

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