**5. Conclusion, perspective, and future directions**

Taken together, in this chapter, we discussed the important roles that epigenetic enzymes play in a variety of cancers. We also summarized several popular methods currently used for screening small molecule inhibitors of epigenetic enzymes. As shown in **Table 1**, we provided a list of representative small molecule inhibitors of HMT that are either FDA approved, or at preclinical or different stages of clinical trials. Notably, compared to the well-developed HDAC small molecule inhibitors, the development of small molecule inhibitors for HMTs is a rising and cutting-edge drug development area. We can envision that in the next 5~10 years, intense attention will continuously be drawn to the discovery of HMTs small molecule inhibitors. We have no doubt that many HMTs small molecule inhibitors will be shifted into clinical trials, more will be approved by FDA, and most likely, more members of HMTs will be targeted for cancer treatment. Additionally, it is very possible that novel HTS methods will emerge, which will further accelerate the discovery of anti-HMTs drugs. Moreover, it is viable that the clinical indications of HMTs small molecule inhibitors could be further expanded to other diseases beyond cancer. In summary, the development of new classes of anti-HMTs drugs will offer brand new and exciting opportunities for diseases treatment.
