Regex replace in Spyder with case conversion

Question

I would like to convert a string from camelCase to snake_case using regex. I could do this using python through the terminal or a text editor I am more familiar with, but I would like to know if this is possible in the built-in search and replace of Spyder. I am able to catch the groups, using

Pattern:      ([a-z])([A-Z])
Replace with: \1\2

, but not to convert the case like I read here.