Suffering-focused ethics is a family of views in normative ethics that assign primary moral importance to the alleviation of suffering. Negative utilitarianism is one example of a suffering-focused ethical view, though other views in this family also assign intrinsic value to things besides suffering, including positive hedonic states as well as non-hedonic states.
Aird, Michael (2020) Collection of evidence about views on longtermism, time discounting, population ethics, significance of suffering vs happiness, etc. among non-EAs, Effective Altruism Forum, May 10.
Many additional resources with some relevance to this topic.
Gloor, Lukas (2016) The case for suffering-focused ethics, Center on Long-Term Risk, August 26.