cites two most relevant papers, one of which is specifically about the strategy to replace the chemotherapeutically depleted T cells with in vitro expanded ones, post chemotherapy. It's certainly possible, though, not enough studies have been conducted, and will probably depend on which chemotherapeutic compound is administering (small molecules tend to have differential spectra of activities). Doxycycline, in mice in at least one study was shown to have no particular effect on immunotherapeutic effect. Gemcitabine, which does do some immunosuppression but doesn't activate BER - so it only affects a subset of immune cells, does potentiate immunotherapies.