We loaded the mapping between COSMIC and DepMap IDs at point in the past and we don’t currently have a process to periodically update the mapping.
Some DepMap IDs might not have a corresponding COSMIC ID if they’re not in COSMIC’s collection, but it can also be the case that we don’t have the COSMIC ID because the line was added to our registration after the last time that we loaded the COSMIC ID → DepMap ID mappings.
We’re currently exploring how to better keep our registration system in sync with other resources, so you can expect that to improve in the future. However, in the mean time, if you want to check any lines, I’d recommend checking with Sanger’s Cell Line Passport or Cellosaurus because they also information about which lines correspond to different IDs and it’s possible that they have some COSMIC IDs that we’re missing.
On both sites you can look up a DepMap ID and get a page containing all the IDs associated with that line, which includes COSMIC.
For example: Cell Model Passports and Cellosaurus cell line CAL-72 (CVCL_1113)
We will eventually get our mapping updated as well, but I don’t have an estimate for when to expect that.