There was a paper published last year by this group where they did a study of Cancer patients (and a bigger study in mice) receiving a particular kind of Chemo,

There was a paper published last year by this group where they did a study of Cancer patients (and a bigger study in mice) receiving a particular kind of Chemo, and their immune systems post therapy were basically 'rebooted'. The protocol in that work was a periodic 2 day water fast in 6 cycles timed with the Chemotherapy adminstration. They then did a very small pilot study and saw the reversal of immunosenescence in people who did the cyclic fasting without Chemotherapy. It was a reasonable effect, but the human studies were smallish and probably could use more reproduction.