TYPO3 Core

I'm trying to make a configuration like this to work for my own Extbase extension:
1) TCEMAIN.clearCacheCmd = cacheTag:tx_iantest

Testing it, it doesn't clear the pages cache with tags like tx_iantest_123.

Instead this one works for tags like tx_news_123:
2) TCEMAIN.clearCacheCmd = cacheTag:tx_news

Even if I placed both config 1 & 2 in the Page TSconfig of the page with news records, where the config number 2 works, the config number 1 doesn't seem to have effect. By example: it doesn't delete records LIKE 'tx_iantest' in cache_pages_tags while config number 2 does delete records LIKE 'tx_news'.