CRISPR was literally discovered in random bacteria, you can’t just not look at anything that has promising leads. Grant funded research requires you to apply for this money and preliminary data is given as reasoning for why the researcher should be funded for what they are interested in looking at, so this could have had very promising preliminary data for them to even get this far. Also not every treatment works for every single person, if CRISPR ever becomes a widespread treatment option it doesn’t guarantee that it works for every single person, immunotherapy has this very issue.

Source: Am a PhD candidate in a renowned cancer immunology lab