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Purpose of this study is to explore the preclinical efficacy of Chondroitin Sulfate Proteoglycan 4 (CSPG4)-specific CAR-engineered Cytokine-Induced Killer lymphocytes (CIK) to eradicate melanoma cells with defective HLA class I (HLA-I). The latter abnormality plays a major role in clinical resistance to Checkpoint Inhibitors (CI). CSPG4 was selected as the target because of its high expression on melanoma and its restricted distribution in normal tissues. Our approach is based on CAR.CIK redirected against CSPG4. CIK, ex vivo expanded T-NK lymphocytes endowed with intrinsic HLA-independent antitumor activity, were used as effectors. Experimental procedure. CAR.CIK were generated by retroviral transduction of patient derived PBMC with a vector encoding a 2nd generation CSPG4-CAR with 4-1BB co-stimulation. Surface HLA-I expression was evaluated by flow cytometry on melanoma cell lines (Mel), derived by surgical biopsies. These cells also served as targets for CSPG4 CAR.CIK. The activity of CSPG4 CAR.CIK was analyzed in vitro and in immunodeficient mice grafted with a patient-derived HLA-defective melanoma. Mice were treated intravenously with 3x106 CAR.CIK (5 cells infusions in total). Results. CAR.CIK were efficiently generated from 4 melanoma patients. Mean expression of CSPG4-CAR was 48±8%, the rate of ex vivo expansion (84 fold) and phenotypic characteristics (CD3+CD8+=71±13%, CD3+ CD56+=22.5±13%, NKG2D+= 68±32.3%) were comparable with unmodified controls. Membrane HLA-I molecules were detected in 23/24 Mel samples, with a variable membrane density per cell (median 21232, range 787-49871). Sample Mel17 did not express HLA-I because of a start lost mutation (p.Met1Ile) in β2microglobulin. CSPG4 was intensely expressed by all Mel (78±5%), with no correlation to HLA-I levels. CSPG4 CAR.CIK efficiently killed 10 Mel samples in vitro, including Mel17 (HLA-I negative) and 2 Mel with the lowest HLA-I density (Mel71, Mel72). Mean Mel-specific killing by CSPG4 CAR.CIK was significantly higher compared with unmodified CIK especially at low effector/target (E/T) ratios (85% vs 40% at E/T=1:1; 46% vs 9% at E/T=1:8, p Conclusions. We reported the activity of CSPG4 CAR.CIK against melanoma, including those with low or defective HLA-I expression. CIK may provide a valid platform for CAR-based strategies against melanoma and solid tumors in general. Our data provide the rationale to implement clinical studies exploring the proposed strategy in melanoma patients not responding or relapsing after immunotherapy with CI. Citation Format: Giulia Cattaneo, Lidia Giraudo, Loretta Gammaitoni, Ilenia Iaia, Fabrizio Carnevale-Schianca, Alberto Pisacane, Enrico Berrino, Caterina Marchiò, Luca Paruzzo, Andrea Michela Biolato, Chiara Donini, Marco Basiricò, Elisa Landoni, Soldano Ferrone, Valeria Leuci, Massimo Aglietta, Gianpietro Dotti, Dario Sangiolo. CSPG4-specific CAR.CIK lymphocyte-based immunotherapy to eliminate HLA class I-defective melanoma tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2812.

Cancers of Unknown Primary (CUPs), featuring metastatic dissemination in the absence of a primary tumor, anatomically or histologically recognizable through a standardized work-up, are a fatal disease and still a biological enigma. Here, we propose CUPs as a distinct, yet unrecognized, pathological entity originating from stem-like cells endowed with unique properties, irrespective of their different genetic backgrounds. These cells were isolated and long-term propagated in vitro in highly stringent conditions as ‘agnospheres', and serially transplanted in vivo, displaying an extremely high tumorigenic potential and reproducing the undifferentiated histology of the original tumors. Early after subcutaneous engraftment, agnospheres recapitulated the CUP clinical presentation, as they spontaneously and quickly disseminated, establishing widespread metastases and retracing the whole metastatic cascade. Agnospheres invariably displayed cell-autonomous proliferation and self-renewal, mostly relying on unrestrained activation of the MAP kinase/MYC axis. This feature conferred sensitivity to MEK inhibitors, which induced apoptosis in vitro and impaired in vivo growth and dissemination. We generated and validated a transcriptional signature that, applied to original tumors, predicts eligibility to MEK inhibition in 75% of CUP patients. Altogether, these findings shed light on CUP biology, unveiling an opportunity for a targeted therapeutic intervention and, concomitantly, provide a novel in vivo model, suitable for assessing molecular determinants of the metastatic cascade. Citation Format: Federica Verginelli, Alberto Pisacane, Gennaro Gambardella, Antonio D'Ambrosio, Ermes Candiello, Marco Ferrio, Mara Panero, Laura Casorzo, Silvia Benvenuti, Eliano Cascardi, Rebecca Senetta, Elena Geuna, Andrea Ballabio, Filippo Montemurro, Anna Sapino, Paolo M. Comoglio, Carla Boccaccio. Hypermetastatic stem-like cells from 'cancer of unknown primary' (CUP) model multi-organ dissemination and unveil liability to MEK inhibition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2871.

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. Cancer Res; 74(1); 119–29. ©2013 AACR.

Purpose: The goals of this study are i) to analyze the expression of human leukocyte antigen class I (HLA-I) antigen processing machinery (APM) components in surgically removed melanoma tumors, ii) to assess their modulation by Interferons (IFNs) and iii) to determine their value as predictive biomarkers of the clinical response to immunotherapy with checkpoint inhibitors (CI). Methods: The expression levels of HLA class I APM components [HLA-I (ABC) chains, beta(2)microglobulin (β2m), Calnexin, Calreticulin, ERp57, Tapasin, TAP1-2, LMP2, LMP7, LMP10] were evaluated by staining with mAbs and flow cytometry in melanoma cells isolated from surgical biopsies from 16 patients with advanced melanoma. In addition the modulation of these molecules by IFN-γ or IFN-α2 (IFNs) was evaluated. Results: The frequency of cells expressing HLA-I/β2m was >90% in 15/16 Mel tumors. In 1 case extracellular HLA-I/β2m molecules were not detected. The expression levels of extracellular HLA class I APM molecules were quite heterogeneous. Based on Mean Fluorescence Intensity (MFI) of HLA-I/β2m, Mel segregated into 2 groups with high (MFI >200, n=8) and low (MFI Conclusions: We report a wide heterogeneous distribution of HLA-I/β2m expression levels and deficits of APM components in Melanoma, partially restorable by IFNs. Our data support the possibility that defects in HLA expression, not responsive to IFN restoration, may predict low responsiveness to CI. We provide rationale to incorporate the evaluation of HLA-I/β2m and APM in clinical immunotherapy studies with CI. Citation Format: Lidia Giraudo, Loretta Gammaitoni, Bortolot Valentina, Ilenia Iaia, Giulia Cattaneo, Paolo Becco, Susanna Gallo, Alessandro Zaccagna, Alberto Pisacane, Luca Crotto, Soldano Ferrone, Massimo Aglietta, Fabrizio Carnevale Schianca, Dario Sangiolo. Expression and modulation by IFN of HLA class I APM components in melanoma: Potential biomarkers of clinical response to checkpoint inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 569.

Purpose of the study was to explore the activity of cytokine-induced killer (CIK) cells against autologous chemo-surviving melanoma cancer stem cells (mCSCs) in vivo. Elimination of mCSCs is an ambitious goal as considered responsible for chemo-resistance and relapses. CIK cells are ex vivo expanded T-NK lymphocytes with MHC-independent antitumor activity. We provided proof of concept that CIK cells can kill mCSCs in vitro (Gammaitoni et al. Clin Cancer Res 2013) and demonstration of their activity in vivo, within an autologous model, would be relevant in clinical perspective. Experimental procedures and results. In vivo activity of CIK cells against autologous mCSCs was explored in NOD/SCID mice bearing tumors generated by subcutaneous implantation of primary melanoma cells or alternatively surgically resected tumor samples (patient-derived xenografts, PDX). mCSCs were visualized by a lentiviral CSC-detector encoding eGFP under control of stem-gene promoter OCT4 (Gammaitoni et al. Clin Cancer Res 2013). Melanoma cells were engineered with the CSC-detector before implantation or alternatively, in PDX, after removal of residual tumors at the end of experimental treatments. In vivo chemotherapy (CHT) consisted of intravenous (i.v.) Fotemustine (600μg days 1;15). Immunotherapy consisted of i.v. CIK cells (1×107) every 5 days. Antitumor activity was evaluated assessing tumor proliferative index by Ki67 expression in residual tumors. Activity against mCSCs was evaluated assessing the rate of residual GFP+-mCSCs in residual tumors after treatments. In vivo infusion of CIK cells for 2 weeks determined significant tumor response (n = 6, p < 0.0001) that fully involved autologous eGFP+-mCSCs. On the contrary, CHT spared mCSCs that resulted significantly increased in residual tumors compared with mice treated with CIK cells (p = 0.001) or untreated controls (p = 0.001). CIK cells infused after a previous CHT treatment (n = 6) retained significant antitumor activity (p = 0.001) and were capable to revert the CHT-induced enrichment of eGFP+-mCSCs, compared to mice treated with CHT alone (p = 0.01). Similarly, in the PDX model, the infusion (n = 4) of autologous CIK cells exerted significant antitumor activity that involved eGFP+mCSCs (p = 0.009), confirmed by the absence of their increment in residual tumors (p = 0.3). In vitro CHT treatment of melanoma from 8 different patients significantly enriched eGFP+ mCSCs (2.2 ±0.2 fold, p = 0.0018) compared to untreated controls. Melanoma treated with CHT, enriched in eGFP+mCSCs, were efficiently killed by autologous CIK cells with mean killing values ranging from 94±2% (40:1 E/T) to 21%±4 (1:3 E/T). Conclusions. Our findings provide first demonstration that immunotherapy with CIK cells is active against autologous mCSCs, surviving chemotherapy, in vitro and in vivo. We provide an experimental platform to study mCSCs and rationale to design clinical studies with CIK cells against melanoma. Citation Format: Loretta Gammaitoni, Lidia Giraudo, Marco Macagno, Giulia Cattaneo, Valeria Leuci, Francesco Sassi, Alessandro Zaccagna, Alberto Pisacane, Valentina Coha, Fabrizio Carnevale-Schianca, Massimo Aglietta, Dario Sangiolo. Effective immunotherapy with cytokine-induced killer cells against autologous melanoma cancer stem cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2290.