Discussion
ACT is an important component of anti-tumor therapies. Although CIK cell immunotherapy has been confirmed to be effective in solid tumors, many patients still display no response to ACT. The mechanisms controlling which patients will respond to CIK cell immunotherapy are still unclear. Naïve T cells that develop in the thymus have long-term persistence over the human lifespan that could drive immune responses to new antigens. Expansion of immune cells is an essential part of ACT immunotherapies. It is likely that innate humoral and cellular immune deficiencies, including inherent T cell defects, will lead to T cell exhaustion and treatment failure. We showed that the patients who reached CR/PR after CIK therapy had higher absolute numbers of naïve CD4+and naïve CD8+ cells. Patients who achieved PR or CR by CIK therapy also had higher absolute numbers of naïve CD4+ and CD8+ T cells in heparinized peripheral blood.
Data from several preclinical immunotherapy studies suggest that the ability of T cells to engraft following adoptive transfer is related to their state of differentiation, and effector CD8+ T cells derived from naïve rather than memory subsets possess superior traits for ACT [8-11]. Naïve T cells present in the periphery since birth are highly proliferative, with long telomeres and high levels of telomerase activity [22-26]. Based on these studies, we investigated whether CIK cells amplified from patients with high naïve T cell numbers had more activity and cytotoxicity and found that the proliferation rate of CIK cells from patients with high absolute numbers of naïve T cells was significantly greater than in patients with low numbers of naïve T cells. Our findings showed that patients with high absolute numbers of naïve T cells could produce more CIK cells, indicating that naïve T cells play an important role in CIK immunotherapy.
A study of CAR T immunotherapy found that CAR T cells derived from a shorter duration of ex vivo culture could product less differentiated T cells, significantly enhanced effector function and enhanced immunological activity in vivo [27]. To understand whether naïve T cells were a critical factor that could affect the response to CIK immunotherapy, we checked the frequencies and absolute number of T cell phenotypic markers in CIK immunotherapy patients at days 5, 15 and 20. The frequency of effector-memory phenotype CD8+ T cells (IFN-γ+CD3+) was higher in patients with high vs low numbers of naïve T cells. The higher frequency of effector-memory phenotype CD8+ T cells (IFN-γ+CD3+) was associated with higher numbers of Ki67+CD3+CD56+cells in these patients. These findings indicated that CIK cells harvested from patients with high absolute numbers of naïve CD4+ and naïve CD8+ cells could produce more CIK cells and maintain sustained antitumor activity.
ACT is a major immunotherapy, as some clinical trials have demonstrated [28, 29]. CIK immunotherapy has potential benefits for several solid tumors including NSCLC; however, the factors that determine which patients will have a positive response to CIK immunotherapy are still unclear. In our study, in order to confirm that naïve T cells play an important role in CIK immunotherapy, we first analyzed the relationship between clinical response and naïve T cell content after CIK treatment. We found that the ORR was 13.2% (9 of 68), but the ORR in patients with high counts of naïve T cells patients was 35% (6 of 17) compared to 5.9% (3 of 51) in patients with low counts. Moreover, 2.9% of patients (2 of 68) showed CR and 10.3% (7 of 68) showed PR, but only one of the CR patients had a low naïve T cell count. In addition, 23.5% (16 of 68) of patients achieved SD and a DCR of 42.6% (29 of 68).
In summary, our results suggested that amplification of CIK cells from patients with high numbers of naïve T cells significantly enhanced effector function, enhanced proliferative capacity and improved anti-tumor efficacy in vivo . The patients with high absolute numbers of naïve T cells in circulating blood had a better response to ACT, which demonstrated the potential of using pretreatment biomarkers of response in ACT. The frequency of naïve T cells in circulating blood may serve as a biomarker to identify which patients will have a better response to CIK cell immunotherapy. Our study thus provides critical information to establish highly efficient CIK cell immunotherapy that may be applicable in various clinical settings.
Disclosure of potential conflicts of interest: All authors have declared that they have no conflicts of interest regarding this work.
Acknowledgments: This work was supported by a grant from the National Natural Science Foundation for Young Scholar of China (81402560),the National Natural Science Foundation of China (81572865 and 81472387), and the Guangdong Province Science and Technology Plan Project (2013B021800063).
References
[1] Rosenberg S A , Restifo N P . Adoptive cell transfer as personalized immunotherapy for human cancer. Science.2015;348:62-68.
[2] June C H , Riddell S R , Schumacher T N . Adoptive cellular therapy: A race to the finish line. Science translational medicine.2015;7:280ps7.
[3] De Witte MA, Kierkels GJ, Straetemans T, et al. Orchestrating an immune response against cancer with engineered immune cells expressing αβTCRs, CARs, and innate immune receptors: an immunological and regulatory challenge. Cancer Immunol Immunother.2015;64:893-902.
[4] Li JJ, Gu MF, Pan K, et al. Autologous Cytokine-induced Killer Cell Transfusion in Combination With Gemcitabine Plus Cisplatin Regimen Chemotherapy for Metastatic Nasopharyngeal Carcinoma. Journal of Immunotherapy.2012;35:189-195.
[5] Lee JH, Lee JH, Lim YS, et al., Adjuvant immunotherapy with autologous cytokine-induced killer cells for hepatocellular carcinoma. Gastroenterology. 2015 ;148(7):1383-1391.
[6] Xu L, Wang J, Kim Y, et al. A randomized controlled trial on patients with or without adjuvant autologous cytokine-induced killer cells after curative resection for hepatocellular carcinoma. OncoImmunology. 2016; 5: e1083671.
[7] Gattinoni L, Lugli E, Ji Y, et al. A human memory T cell subset with stem cell-like properties. Nature medicine.2011;17:1290-1297.
[8] Berger C, Jensen MC, Lansdorp PM, et al. Adoptive transfer of effector CD8+ T cells derived from central memory cells establishes persistent T cell memory in primates. Journal of Clinical Investigation.2008;118:294-305.
[9] Graef P, Buchholz VR, Stemberger C, et al. Serial Transfer of Single-Cell-Derived Immunocompetence Reveals Stemness of CD8+ Central Memory T Cells. Immunity.2014;41:116-126.
[10] Hinrichs CS, Borman ZA, Gattinoni L, et al. Human effector CD8+ T cells derived from naive rather than memory subsets possess superior traits for adoptive immunotherapy. Blood.2011;117:808-814.
[11] Joseph A. Fraietta, Simon F. Lacey, Elena J. Determinants of response and resistance to CD19 chimeric antigen receptor (CAR) T cell therapy of chronic lymphocytic leukemia. Nat Med. 2018;24:563-571.
[12] Tanel A, Fonseca SG, Yassine-Diab B, et al. Cellular and molecular mechanisms of memory T-cell survival. Expert Review of Vaccines. 2009;8:299-312.
[13] Gattinoni L, Klebanoff CA, Palmer DC, et al. Acquisition of full effector function in vitro paradoxically impairs the in vivo antitumor efficacy of adoptively transferred CD8+ T cells. Journal of Clinical Investigation.2005;115:1616-1626.
[14] Klebanoff CA, Gattinoni L, Restifo NP. Sorting through subsets: which T cell populations mediate highly effective adoptive immunotherapy? J Immunother. 2012;35:651-660.
[15] Lugli E, Dominguez MH, Gattinoni L,et al. Superior T memory stem cell persistence supports long-lived T cell memory. J Clin Invest. 2013;123:594-599.
[16] Klebanoff CA, Gattinoni L, Palmer DC, et al. Determinants of successful CD8(+) T cell adoptive immunotherapy for large established tumors in mice. Clin Cancer Res. 2011;17:5343-5352.
[17] Chapuis AG, Thompson JA, Margolin KA, et al. Transferred melanoma-specific CD8+ T cells persist, mediate tumor regression, and acquire central memory phenotype. Proc Natl Acad Sci. 2012;109:4592-4597.
[18] Powell DJ, Dudley ME, Robbins PF, et al. Transition of late-stage effector T cells to CD27+ CD28+ tumor-reactive effector memory T cells in humans after adoptive cell transfer therapy. Blood. 2005;105:241-250.
[19] Huang J, Khong HT, Dudley ME, et al. Survival, persistence, and progressive differentiation of adoptively transferred tumor-reactive T cells associated with tumor regression. J Immunother. 2005;28:258-267.
[20] Huang J, Kerstann KW, Ahmadzadeh M, et al. Modulation by IL-2 of CD70 and CD27 expression on CD8+ T cells: importance for the therapeutic effectiveness of cell transfer immunotherapy. J Immunol. 2006;176:7726-7735.
[21] Chen CL, Pan QZ, Weng DS, et al. Safety and activity of PD-1 blockade-activated DC-CIK cells in patients with advanced solid tumors. Oncoimmunology. 2018; 7: e1417721.
[22] Palmer DB. The effect of age on thymic function. Front Immunol. 2013; 4:316.
[23] Hale JS, Boursalian TE, Turk GL, et al. Thymic output in aged mice. Proc Natl Acad Sci USA. 2006; 103:8447–8452.
[24] Sallusto F, Geginat J, Lanzavecchia A. Central memory and effector memory T cell subsets: function, generation, and maintenance. Annu Rev Immunol. 2004;22: 745–763.
[25] Sallusto F, Lenig, D, Forster, R, et al. Two subsets of memory T lymphocytes with distinct homing potentials and effector functions. Nature.1999; 401:708–712.
[26] Okhrimenko A, Grün JR, Westendorf K, et al. Human memory T cells from the bone marrow are resting and maintain long-lasting systemic memory. Proc Natl Acad. Sci. 2014;111:9229–9234.
[27] Ghassemi S, Nunez-Cruz S, O’Connor RS, et al. Reducing Ex Vivo Culture Improves the Antileukemic Activity of Chimeric Antigen Receptor (CAR) T Cells. Cancer Immunol Res. 2018;6:1100-1109.
[28] Schmidt-Wolf, Negrin RS, Kiem HP, et al., Use of a SCID mouse/human lymphoma model to evaluate cytokine-induced killer cells with potent antitumor cell activity. J Exp Med. 1991;174(1):139-49.
[29] Schmeel LC, Schmeel FC, Coch C, et al., Cytokine-induced killer (CIK) cells in cancer immunotherapy: report of the international registry on CIK cells (IRCC). J Cancer Res Clin Oncol. 2015;141(5):839-49.