Apparently there’s a lot of them, not yet published. I guess the main issue is whether the state (Israel in this case) will snatch them before a Kafka’s friend’s grandchildren have the chance to auction them off. Excerpt:
The bulk of the collection remained divided among an apartment on Spinoza Street in central Tel Aviv and 10 safe-deposit boxes in Tel Aviv and Zurich. It is unclear how much of Brod’s estate is still housed in the Spinoza Street apartment, which is currently inhabited by Eva Hoffe and between 40 and 100 cats. Eva’s neighbors, as well as members of the international scholarly community, have expressed concern regarding the effects of these cats on their surroundings. More than once, municipal authorities have removed some of the animals from the premises, but the missing cats always seem to be replaced.
Read more here.