** Shares of drug developer Fulcrum Therapeutics FULC.O jump 49.4% to $13.30 premarket

** Flucrum said on Sunday its experimental drug showed positive results in patients with sickle cell disease from an ongoing 20 dose cohort of an early-stage trial

** Sickle cell disease is an inherited blood disorder that affects the hemoglobin in red blood cells

** In a 12-patient study, the company is testing the safety and efficacy of its experimental drug, pociredir, an oral once-daily HbF inducer

** FULC says every patients in the study experienced a significant rise in fetal hemoglobin (HbF) levels after treatment

** Company plans to re-engage with the FDA in H1 2026

** RBC Capital Markets says it remains on the sidelines, awaiting further regulatory clarity around Fulcrum Therapeutics' development plans

** "We think it will be important to see... whether regulators will allow FULC to move directly into a pivotal trial or ask for an intermediate Phase II trial first" brokerage adds

** As of last close, stock was up 89.4% YTD

(Reporting by Siddhi Mahatole)

((siddhi.mahatole@thomsonreuters.com))