PMCH and obesity due to melanocortin 4 receptor deficiency: For example, at the hit-to-lead stage, it was almost impossible to separate the chemical feature, leading to high affinity at MCH-R1 from those leading to a strong inhibition of the hErg channel [23,24] and its associated cardiac toxicity, a feature unacceptable at this stage of discovery/development of new anti-obesity drug candidates.