BackgroundGefitinib was the first epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) approved for the treatment of advanced non-small cell lung cancer (NSCLC). Few treatment options are available for NSCLC patients who have responded to gefitinib treatment and demonstrated tumor progression. The present study was conducted to evaluate the efficacy and toxicity of the 2nd EGFR-TKI administration.MethodsWe retrospectively analyzed 11 patients who had obtained a partial response (PR) or stable disease (SD) with gefitinib treatment and were re-treated with EGFR-TKI after failure of the initial gefitinib treatment.ResultsThree patients (27%) were treated with gefitinib as the 2nd EGFR-TKI, and 8 patients (73%) received erlotinib. Only one patient (9%) showed PR, 7 (64%) achieved SD, and 3 (27%) had progressive disease. The disease control rate was 73% (95% CI, 43% - 91%) and the median progression-free survival was 3.4 months (95% CI, 2 - 5.2). The median overall survival from the beginning of the 2nd EGFR-TKI and from diagnosis were 7.3 months (95% CI, 2.7 - 13) and 36.7 months (95% CI, 23.6 - 43.9), respectively. No statistical differences in PFS or OS were observed between gefitinib and erlotinib as the 2nd EGFR-TKI (PFS, P = 0.23 and OS, P = 0.052). The toxicities associated with the 2nd EGFR-TKI were generally acceptable and comparable to those observed for the initial gefitinib therapy.ConclusionsOur results indicate that a 2nd EGFR-TKI treatment can be an effective treatment option for gefitinib responders.

Two new isoflavone glycosides, the 8-C-apiosyl(1•¨6) glucosides of daidzein and genistein,

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Antitumor immunity is augmented by cytotoxic lymphodepletion therapies. Adoptively transferred naive and effector T cells proliferate extensively and show enhanced antitumor effects in lymphopenic recipients. Although the impact of lymphodepletion on transferred donor T cells has been well evaluated, its influence on recipient T cells is largely unknown. The current study demonstrates that both regulatory T cells (Tregs) and effector CD8+ T cells from lymphopenic recipients play critical roles in the development of antitumor immunity after lymphodepletion. Cyclophosphamide (CPA) treatment depleted lymphocytes more efficiently than other cytotoxic agents; however, the percentage of CD4+CD25+ Foxp3+ Tregs was significantly increased in CPA-treated lymphopenic mice. Depletion of these chemoresistant Tregs following CPA treatment and transfer of naive CD4+ T cells augmented the antitumor immunity and significantly suppressed tumor progression. Further analyses revealed that recipient CD8+ T cells were responsible for this augmentation. Using Rag2−/− mice or depletion of recipient CD8+ T cells after CPA treatment abrogated the augmentation of antitumor effects in CPA-treated reconstituted mice. The transfer of donor CD4+ T cells enhanced the proliferation of CD8+ T cells and the priming of tumor-specific CD8+ T cells originating from the lymphopenic recipients. These results highlight the importance of the recipient cells surviving cytotoxic regimens in cancer immunotherapies.

Accumulating evidence suggests that cancer cells possess a small subpopulation that survives during potentially lethal stresses, including chemotherapy, radiation treatment, and molecular-targeting therapy. CD133 is a putative marker that distinguishes a minor subpopulation from normal differentiated tumor cells in many cancers. Although it is necessary to eradicate all cancer cells to obtain a cure, effective treatment to eliminate the CD133(+) treatment-tolerant cells has not been elucidated. In this study, we demonstrated that a CD133(+) subpopulation in murine melanoma is immunogenic and that effector T cells specific for the CD133(+) melanoma cells mediated potent antitumor reactivity, curing the mice of the parental melanoma. CD133(+) melanoma antigens preferentially induced type 17 T helper (Th17) cells and Th1 cells but not Th2 cells. CD133(+) melanoma cell-specific CD4(+) T-cell treatment eradicated not only CD133(+) tumor cells but also CD133(-) tumor cells while inducing long-lasting accumulation of lymphocytes and dendritic cells with upregulated MHC class II in tumor tissues. Further, the treatment prevented regulatory T-cell induction. These results indicate that T-cell immunotherapy is a promising treatment option to eradicate CD133(+) drug-tolerant cells to obtain a cure for cancer.

The adoptive transfer of effector T cells combined with lymphodepletion has demonstrated promising antitumor effects in mice and humans, although the availability of tumor-specific T cells is limited. We and others have also demonstrated that the transfer of polyclonal naïve T cells induces tumor-specific effector T cells and enhances antitumor immunity after lymphodepletion. Because tumors have been demonstrated to induce immunosuppressive networks and regulate the function of T cells, obtaining a sufficient number of fully functional naïve T cells that are able to differentiate into tumor-specific effector T cells remains difficult. To establish culture methods to obtain a large number of polyclonal T cells that are capable of differentiating into tumor-specific effector T cells, naïve T cells were activated with anti-CD3 mAbs in vitro. These cells were stimulated with IL-2 and IL-7 for the CD8 subset or with IL-7 and IL-23 for the CD4 subset. Transfer of these hyperexpanded T cells after lymphodepletion showed significant antitumor efficacy, and tumor-specific effector T cells were primed from these expanded T cells in tumor-bearing hosts. Moreover, these ex vivo—expanded T cells maintained T cell receptor diversity and showed long-term persistence of memory against specific tumors. Further analyses revealed that combination therapy consisting of vaccination with dendritic cells that were co-cultured with irradiated whole tumor cells and the transfer of ex vivo—expanded T cells significantly enhanced antitumor immunity. These results indicate that the transfer of ex vivo—expanded polyclonal T cells can be combined with other immunotherapies and augment antitumor effects.

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