Hyperphagia in rare melanocortin-4 receptor pathway diseases: therapeutic options and assessing treatment response

Hyperphagia is a hallmark of both congenital and acquired rare melanocortin-4 receptor (MC4R) pathway diseases. Currently, the medical community has no standard treatment guidelines or approach to establishing treatment benefit. This narrative review discusses current understandings of the pathophysiology, burden, and treatment of hyperphagia and summarizes findings from a systematic literature review of validated instruments for assessing the response to hyperphagia treatment. Hyperphagia can result from dysfunction within, or damage impacting, hypothalamic pathways including the MC4R pathway, a key regulator of energy balance. The burden of hyperphagia is substantial, with negative effects experienced across physiologic, emotional, and social domains. Approaches for hyperphagia management include environmental control, lifestyle intervention, pharmacotherapy, neurocognitive approaches, and neurostimulation. There are varied approaches to determine treatment response; however, standard methodology has not been determined and largely relies on questionnaires. Studies of rare MC4R pathway diseases have improved understanding of the etiology of hyperphagia and established the need for indication-specific treatment. Targeted treatments are limited, and methods for determining treatment efficacy are varied. There is a need for consensus guidelines to establish a standard approach for the management of hyperphagia and related assessment of treatment response to improve patient morbidity.