Keep in mind, though, that Humira's sales won't evaporate overnight. The drug's international sales declined significantly after biosimilars hit the market, but still topped $1 billion in the first quarter of 2020. More importantly, AbbVie has other arrows in its quiver that will help offset future sales declines for Humira, notable among them new immunology drugs Rinvoq and Skyrizi, and cancer drugs Imbruvica and Venclexta.