Preconditioning chemotherapy with paclitaxel and cisplatin enhances the antitumor activity of cytokine induced-killer cells in a murine lung carcinoma model

Adoptive cell therapy involving the use of ex vivo generated cytokine-induced killer cells (CIKs) provides a promising approach to immunotherapy. However, the therapeutic activity of CIKs is limited by the immunosuppressive factors active in the host. It has become increasingly apparent that manipulation of the recipient immune system with the preconditioning regimen is essential to guarantee the antitumor effect of subsequent adoptive cell therapy. In our study, paclitaxel (PTX) and cisplatin (DDP) were used as preconditioning drugs combined with CIKs to illustrate the potential mechanisms underlying the synergic antitumor effect against Lewis lung cancer cells in vitro and in vivo. We found that 3LL cells displayed an increased sensitization to CIKs-induced lysis after treatment with PTX or DDP in vitro. Significant inhibition of tumor growth was observed in mice treated with combinatorial chemo-immunotherapy with respect to untreated or single regimen treated ones. Prior chemotherapy markedly enhanced the intratumoral accumulation of CD3⁺ T lymphocytes and the homing of CIKs to the spleen and tumor. Moreover, the frequencies of intratumoral and splenic regulatory T cells (Tregs) were significantly decreased after chemotherapy pretreatment. Our findings provide a new rationale for combining immunotherapy and chemotherapy to induce a synergistic antitumor response in patients with lung cancer.