Exhibit 99.1 Rhythm Pharmaceuticals Reports Fourth Quarter 2023 Financial Results and Business Update -- Fourth quarter 2023 net revenue from global sales of IMCIVREE (setmelanotide) of $24.2 million -- -- Enrollment completed in 120-patient, pivotal cohort of Phase 3 setmelanotide trial in hypothalamic obesity; top-line data on track for 1H2025 -- -- Announced Phase 3 development plans for setmelanotide in hypothalamic obesity in Japan -- -- Spain and Italy authorities approve reimbursement for IMCIVREE to ...