Lidia Giraudo

Effective Activity of Cytokine-Induced Killer Cells against Autologous Metastatic Melanoma Including Cells with Stemness Features

Purpose: We investigate the unknown tumor-killing activity of cytokine-induced killer (CIK) cells against autologous metastatic melanoma and the elusive subset of putative cancer stem cells (mCSC). Experimental Design: We developed a preclinical autologous model using same patient-generated CIK cells and tumor targets to consider the unique biology of each patient/tumor pairing. In primary tumor cell cultures, we visualized and immunophenotypically defined a putative mCSC subset using a novel gene transfer strategy that exploited their exclusive ability to activate the promoter of stemness gene Oct4. Results: The CIK cells from 10 patients with metastatic melanoma were successfully expanded (median, 23-fold; range, 11–117). Primary tumor cell cultures established and characterized from the same patients were used as autologous targets. Patient-derived CIK cells efficiently killed autologous metastatic melanoma [up to 71% specific killing (n = 26)]. CIK cells were active in vivo against autologous melanoma, resulting in delayed tumor growth, increased necrotic areas, and lymphocyte infiltration at tumor sites. The metastatic melanoma cultures presented an average of 11.5% ± 2.5% putative mCSCs, which was assessed by Oct4 promoter activity and stemness marker expression (Oct4, ABCG2, ALDH, MITF). Expression was confirmed on mCSC target molecules recognized by CIK cells (MIC A/B; ULBPs). CIK tumor killing activity against mCSCs was intense (up to 71%, n = 4) and comparable with results reported against differentiated metastatic melanoma cells (P = 0.8). Conclusions: For the first time, the intense killing activity of CIK cells against autologous metastatic melanoma, including mCSCs, has been shown. These findings move clinical investigation of a new immunotherapy for metastatic melanoma, including mCSCs, closer. Clin Cancer Res; 19(16); 4347–58. ©2013 AACR.

Cytokine-Induced Killer Cells Eradicate Bone and Soft-Tissue Sarcomas

Unresectable metastatic bone sarcoma and soft-tissue sarcomas (STS) are incurable due to the inability to eradicate chemoresistant cancer stem-like cells (sCSC) that are likely responsible for relapses and drug resistance. In this study, we investigated the preclinical activity of patient-derived cytokine-induced killer (CIK) cells against autologous bone sarcoma and STS, including against putative sCSCs. Tumor killing was evaluated both in vitro and within an immunodeficient mouse model of autologous sarcoma. To identify putative sCSCs, autologous bone sarcoma and STS cells were engineered with a CSC detector vector encoding eGFP under the control of the human promoter for OCT4, a stem cell gene activated in putative sCSCs. Using CIK cells expanded from 21 patients, we found that CIK cells efficiently killed allogeneic and autologous sarcoma cells in vitro. Intravenous infusion of CIK cells delayed autologous tumor growth in immunodeficient mice. Further in vivo analyses established that CIK cells could infiltrate tumors and that tumor growth inhibition occurred without an enrichment of sCSCs relative to control-treated animals. These results provide preclinical proof-of-concept for an effective strategy to attack autologous sarcomas, including putative sCSCs, supporting the clinical development of CIK cells as a novel class of immunotherapy for use in settings of untreatable metastatic disease.

Immunotherapy of cancer stem cells in solid tumors: initial findings and future prospective

Introduction: Conventional chemotherapies seemed to have reached a therapeutic plateau in the treatment of solid tumors and many metastatic diseases are still incurable. Events of chemo-resistance and relapses appear to be sustained by a subset of putative cancer stem cells (CSCs). New anticancer strategies need to face this new challenge exploring their efficacy against CSCs. Immunotherapy has raised enthusiasms in cancer therapy and its potential against CSCs is an intriguing field of research. Areas covered: In this work we reviewed the immunotherapy approaches directed against CSCs in solid tumors. We schematically divided adaptive immunotherapy strategies, mainly based on dendritic cell-vaccination, and strategies exploiting MHC-unrestricted effectors like natural killer cells, γδ T lymphocytes and cytokine-induced killer cells. Findings, strength and limitations of these models are discussed and compared highlighting their potential clinical relevance. Expert opinion: The important biologic role and clinical relevance of CSCs introduced a ‘noble target’ for immunotherapy and cancer treatments in general. Initial evidences suggest that CSCs may be susceptible to various types of immunotherapy attacks, overcoming their chemo-resistance. Investigation of important safety issues, based on shared features with ‘normal’ stem cells, along with intriguing synergisms with modulatory agents are open challenges for the next future and effective clinical translation.

Post-Transplant Cyclophosphamide and Tacrolimus–Mycophenolate Mofetil Combination Prevents Graft-versus-Host Disease in Allogeneic Peripheral Blood Hematopoietic Cell Transplantation from HLA-Matched Donors

Allogeneic hematopoietic cell transplant (HCT) remains the only curative therapy for many hematologic malignancies but it is limited by high nonrelapse mortality (NRM), primarily from unpredictable control of graft-versus-host disease (GVHD). Recently, post-transplant cyclophosphamide demonstrated improved GVHD control in allogeneic bone marrow HCT. Here we explore cyclophosphamide in allogeneic peripheral blood stem cell transplantation (alloPBSCT). Patients with high-risk hematologic malignancies received alloPBSCT from HLA-matched unrelated/related donors. GVHD prophylaxis included combination post-HCT cyclophosphamide 50 mg/kg (days +3 and +4) and tacrolimus/mofetil mycophenolate (T/MMF) (day +5 forward). The primary objective was the cumulative incidence of acute and chronic GVHD. Between March 2011 and May 2015, 35 consecutive patients received the proposed regimen. MMF was stopped in all patients at day +28; the median discontinuation of tacrolimus was day +113. Acute and chronic GVHD cumulative incidences were 17% and 7%, respectively, with no grade IV GVHD events, only 2 patients requiring chronic GVHD immunosuppression control, and no deaths from GVHD. Two-year NRM, overall survival, event-free survival, and chronic GVHD event-free survival rates were 3%, 77%, 54%, and 49%, respectively. The graft-versus-tumor effect was maintained as 5 of 15 patients (33%) who received HCT with evidence of disease experienced further disease response. A post-transplant cyclophosphamide + T/MMF combination strategy effectively prevented acute and chronic GVHD after alloPBSCT from HLA-matched donors and achieved an unprecedented low NRM without losing efficacy in disease control or impaired development of the graft-versus-tumor effect. This trial is registered at clinicaltrials.gov as NCT02300571.

Cytokine-Induced Killer Cells Kill Chemo-surviving Melanoma Cancer Stem Cells

Purpose: The MHC-unrestricted activity of cytokine-induced killer (CIK) cells against chemo-surviving melanoma cancer stem cells (mCSC) was explored, as CSCs are considered responsible for chemoresistance and relapses. Experimental Design: Putative mCSCs were visualized by engineering patient-derived melanoma cells (MC) with a lentiviral vector encoding eGFP under expression control by stemness gene promoter oct4. Their stemness potential was confirmed in vivo by limiting dilution assays. We explored the sensitivity of eGFP+ mCSCs to chemotherapy (CHT), BRAF inhibitor (BRAFi) or CIK cells, as single agents or in sequence, in vitro. First, we treated MCs in vitro with fotemustine or dabrafenib (BRAF-mutated cases); then, surviving MCs, enriched in mCSCs, were challenged with autologous CIK cells. CIK cell activity against chemoresistant mCSCs was confirmed in vivo in two distinct immunodeficient murine models. Results: We visualized eGFP+ mCSCs (14% ± 2.1%) in 11 MCs. The tumorigenic precursor rate in vivo was higher within eGFP+ MCs (1/42) compared with the eGFP− counterpart (1/4,870). In vitro mCSCs were relatively resistant to CHT and BRAFi, but killed by CIK cells (n = 11, 8/11 autologous), with specific lysis ranging from 95% [effector:tumor ratio (E:T), 40:1] to 20% (E:T 1:3). In vivo infusion of autologous CIK cells into mice bearing xenografts from three distinct melanomas demonstrated significant tumor responses involving CHT-spared eGFP+ mCSCs (P = 0.001). Sequential CHT–immunotherapy treatment retained antitumor activity (n = 12, P = 0.001) reducing mCSC rates (P = 0.01). Conclusions: These findings are the first demonstration that immunotherapy with CIK cells is active against autologous mCSCs surviving CHT or BRAFi. An experimental platform for mCSC study and rationale for CIK cells in melanoma clinical study is provided. Clin Cancer Res; 23(9); 2277–88. ©2016 AACR.

Cytokine-induced killer cells as immunotherapy for solid tumors: current evidence and perspectives

Cytokine-induced killer (CIK) cells are ex vivo expanded T lymphocytes endowed with potent MHC-independent antitumor activity. CIK cells are emerging as promising therapeutic approach in the field of cancer adoptive immunotherapy, with biologic features favoring their transferability into clinical applications. Aim of this review is to present the biologic characteristic of CIK cells, discussing the main preclinical findings and initial clinical applications in the field of solid tumors.

Adoptive immunotherapy against sarcomas.

Introduction: Conventional treatments reached an unsatisfactory therapeutic plateau in the treatment of advanced unresectable bone and soft tissue sarcomas that remain an unsolved medical need. Several evidences support the concept that adoptive immunotherapy may effectively integrate within the complex and multidisciplinary treatment of sarcomas. Areas covered: In this work we reviewed adoptive immunotherapy strategies that have been explored in sarcoma settings, with specific focus on issues related to their clinic transferability. We schematically divided approaches based on T lymphocytes specific for MHC-restricted tumor-associated antigens or relying on MHC-independent immune effectors such as natural killer (NK), cytokine-induced killer (CIK) or γδ T cells. Expert opinion: Preclinical findings and initial clinical reports showed the potentialities and drawbacks of different adoptive immunotherapy strategies. The expansion of tumor infiltrating lymphocytes is difficult to be reproduced outside melanoma. Genetically redirected T cells appear to be a promising option and initial reports are encouraging against patients with sarcomas. Adoptive immunotherapy with MHC-unrestricted effectors such as NK, CIK or γδ T cells has recently shown great preclinical potential in sarcoma setting and biologic features that may favor clinical transferability. Combination of different immunotherapy approaches and integration with conventional treatments appear to be key issues for successful designing of next clinical trials.

BRAF and MEK inhibitors increase PD1-positive melanoma cells leading to a potential lymphocyte-independent synergism with anti-PD1 antibody

Purpose: BRAF and MEK inhibitors (BRAF/MEKi) favor melanoma-infiltrating lymphocytes, providing the rationale for current combinatorial trials with anti–PD-1 antibody. A portion of melanoma cells may express PD-1, and anti–PD-1 antibody could have a direct antitumor effect. Here, we explore whether BRAF/MEKi modulate rates of PD-1+ melanoma cells, supporting an additional—lymphocyte-independent—basis for their therapeutic combination with anti–PD-1 antibody. Experimental Design: With data mining and flow cytometry, we assessed PD-1, PD-L1/2 expression on melanoma cell lines (CCLE, N = 61; validation cell lines, N = 7) and melanoma tumors (TCGA, N = 214). We explored in vitro how BRAF/MEKi affect rates of PD-1+, PD-L1/2+ melanoma cells, and characterized the proliferative and putative stemness features of PD-1+ melanoma cells. We tested the functional lymphocyte-independent effect of anti–PD-1 antibody alone and in combination with BRAF/MEKi in vitro and in an in vivo immunodeficient murine model. Results: PD-1 is consistently expressed on a small subset of melanoma cells, but PD-1+ cells increase to relevant rates during BRAF/MEKi treatment [7.3% (5.6–14.2) vs. 1.5% (0.7–3.2), P = 0.0156; N = 7], together with PD-L2+ melanoma cells [8.5% (0.0–63.0) vs. 1.5% (0.2–43.3), P = 0.0312; N = 7]. PD-1+ cells proliferate less than PD-1− cells (avg. 65% less; t = 7 days) and are preferentially endowed with stemness features. In vivo, the direct anti-melanoma activity of PD-1 blockage as monotherapy was negligible, but its association with BRAF/MEKi significantly delayed the development of drug resistance and tumor relapse. Conclusions: BRAF/MEKi increase the rates of PD-1+ melanoma cells that may sustain tumor relapse, providing a lymphocyte-independent rationale to explore combinatory strategies with anti–PD-1 antibody. Clin Cancer Res; 24(14); 3377–85. ©2018 AACR.

Cytokine Induced Killer cells effectively kill chemo-resistant melanoma cancer stem cells

Background Metastatic Melanoma (mMel) is considered refractory to conventional chemotherapies. New molecular targeted approaches, inhibiting mutated forms of the serinethreonine kinase B-RAF, significantly increased the response rate but patients almost invariably relapse and prognosis remains severe [1,2]. Open challenge is the characterization and targeting of cancer stem cells (CSCs), considered responsible for chemoresistance and disease relapse. Adoptive immunotherapy holds great promises for the treatment of mMel and research efforts are ongoing to explore its potential activity against melanoma CSCs (mCSCs). Cytokine Induced Killer (CIK) cells are a subset of ex vivo expanded T lymphocytes with mixed CD3CD56 phenotype and endowed with HLA-unrestricted tumor killing activity. We and others recently reported the preclinical activity of CIK cells against several solid tumors including mMel [3]. Aim of our research is to explore the preclinical activity of CIK cells against autologous mCSCs surviving treatments with chemo or molecular targeted therapies.

Ex Vivo-Activated MHC-Unrestricted Immune Effectors for Cancer Adoptive Immunotherapy

Adoptive immunotherapy is considered a promising strategy for the treatment of metastatic tumors and current research efforts are directed to define the optimal approach and facilitate the transferability from preclinical to clinical settings. Among several approaches it is possible to schematically distinguish strategies based on either MHC-restricted or MHC-unrestricted immune effectors. The first are mainly based on the infusion of tumor-specific T lymphocytes capable of recognizing determined MHC-restricted tumor associated antigens (TAA) through their T cell receptor. MHC-unrestricted approaches do not target specific tumor associated antigens and are mainly mediated by effectors of the innate immune system, like natural killer (NK) cells or NKT cells, first barrier against pathogens and tumorigenesis processes, or by ex vivo activated lymphocytes like cytokine-induced killer (CIK) cells. MHC-unrestricted effectors are usually more abundant than TAA-specific precursors and easier to expand. Furthermore their activity is not restricted to precise HLA-haplotypes, not limited to a single tumor histotype and could overcome downregulation of MHC molecules operated by tumor cells as immune escape mechanism. In this review we will discuss the main cancer immunotherapy strategies based on MHC-unrestricted immune effectors. The topic will be approached from the angle of ex vivo expansion protocols in clinical prospective, as well as potential approaches to favorably modulate their functions.