** Shares of drug developer Disc Medicine IRON.O fall 13% to $78.86

** FDA official Vinay Prasad is questioning the effectiveness of Disc Medicine's experimental drug, bitopertin, for treating a rare blood disorder, brokerage Truist Securities said in a note, quoting a report in STAT News

** IRON's bitopertin for porphyria is one of the nine products under FDA Commissioner's National Priority Voucher program announced in October

** Truist says "we note that Prasad does not oversee the FDA Division that would typically conduct the filing review, however, he is part of the committee that chooses which products to award the CNPV vouchers"

** Vinay Prasad was recently appointed as director at FDA's Center for Biologics Evaluation and Research

** Brokerage adds that the IRON stock "is trading as if accelerated approval is no longer viable"; however, the existing data still supports a pathway for accelerated approval

** "Even if the CNPV committee ultimately declines to grant approval by the end of January 2026, we think a traditional accelerated approval should still remain an option, implying a modest shift in launch timing to the late May - September window" Truist adds

** Including session's move, stock up ~28% YTD

(Reporting by Sahil Pandey and Siddhi Mahatole in Bengaluru)

((Sahil.Pandey@thomsonreuters.com))