Sarcomas are a heterogeneous group of mesenchymal neoplasms, many of which are associated with a high risk of metastasis and poor prognosis. Conventional chemotherapy and targeted therapies have varying effects across individuals and tumour subtypes. The current therapies frequently provide limited clinical benefit; hence, more effective treatments are urgently needed. Recent advances in immunotherapy, such as checkpoint inhibition or adoptive cell therapy (ACT), show potential in increasing efficacy by providing a more personalized treatment. Therapy with tumour-infiltrating lymphocytes (TILs) is an emerging field in immunotherapy. Here, we collected 190 sarcoma tumour specimens from patients without preoperative adjuvant treatment in order to isolate TILs. We compared different methods of TIL expansion and optimized a protocol specifically for efficacy in culturing TILs from sarcoma. The expanded TIL populations were characterized by flow cytometry analysis using CD3, CD4, CD8, CD14, CD19 and CD56 markers. The TIL populations were nonspecifically stimulated to establish TIL reactivity. Through an optimized expansion protocol, TILs were isolated and cultured from 54 of 92 primary sarcoma specimens. The isolated TILs varied in CD4+ and CD8+ T-cell compositions and retained their ability to release IFNγ upon stimulation. Our results suggest that certain sarcoma subtypes have the potential to yield a sufficient number of TILs for TIL therapy.
Sarcoma is a heterogeneous group of connective tissue cancers with over 60 subtypes. Curative treatment relies on surgical resection combined with radiation. In the event of metastasis, chemotherapy is used but generally only with palliative intent. Given the heterogeneity of sarcomas, targeted therapies are limited, which has contributed to the relatively stagnant survival rates seen in the past decades. Objective: Personalized treatments, such as adoptive cell therapy (ACT), may be promising for select sarcoma patients, specifically those with Undifferentiated Pleomorphic Sarcoma (UPS). To better understand ACT’s feasibility for UPS, we aim to investigate the intersection of tumor-infiltrating lymphocytes (TILs) and tumor cells by examining their cytokine output, whose role remains largely unstudied. Methods: Tissue samples from untreated sarcoma patients have been collected and viably preserved by our group. The samples were processed for in vitro expansion of tumor or TIL cell lines. Tumor cultures were validated with Whole Exome Sequencing (WES) to ensure tumor-specific variations were retained. TILs were isolated with tumor fragment (TF) processing and magnetic bead coated anti-CD3/CD28 Rapid Expansion Protocol (REP). After validating tumor cultures, both tumor and TIL-secreted cytokines were evaluated using Luminex assays. Results: Of the 11 primary UPS samples cultured, 10 generated viable cell cultures as defined by the presentation of stable growth beyond passage 5. A total of 3 cell lines were selected for further validation, and through WES, retained tumor specific variations beyond passage 5. On the other hand, the sarcoma-optimized TF and REP protocols expanded TILs from 7 of 8 UPS cases and yielded up to 6 x 10^7 cells. Although IL-2 is commonly used to facilitate TIL growth, it can also cause activation-induced cell death which is problematic for therapy. We demonstrated that an alternative γ-chain interleukin, IL-15, can support UPS TIL growth comparable to IL-2. Unbiased cytokine screening detected anti-tumoral CXCL9/IFN-γ and pro-tumoral IL-10/TGF-Beta as highly secreted by TIL cultures while some tumor cultures secreted relatively high concentrations of IL-6 and CCL2. Conclusion: We developed a robust in vitro pipeline to expand sarcoma tumor cultures and TILs for downstream characterization. Functional assays aimed at dissecting the consequences of tumor-mediated IL-6 secretion are underway. These include siRNA-induced knock downs of genes hypothesized to augment the cytokine profile of tumor cells. Future evaluation of TILs will identify their clinical efficacy via flow cytometry and intracellular cytokine staining. Understanding cytokine secretion from both the tumor and immune components of sarcoma will aid in elucidating interactions within the microenvironment that may be therapeutically relevant. Citation Format: Victoria Coward, Jacky Chen, Nalan Gokgoz, Kim Tsoi, Jay S. Wunder, Irene L. Andrulis. Investigating the undifferentiated pleomorphic sarcoma microenvironment through cytokine profiles of primary tumor and immune infiltrates [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 5609.
Introduction: Sarcoma is a heterogeneous group of connective tissue cancers with over 60 different subtypes. Curative treatment relies on surgical resection combined with radiation. In the event of metastasis, chemotherapy is commonly used but generally only with palliative intent. Given the heterogeneity of sarcomas, targeted therapies are limited and this has contributed to the relatively stagnant survival rates seen in the past decades. Objective: With poorly defined cancer antigens and genetic mutations, more personalized treatments, such as immunotherapy, and in particular adoptive cell transfer therapy (ACT), may be a more viable and promising option for select sarcoma patients than currently available palliative chemotherapy. As such, our study aims to create patient specific models to investigate the interactions between tumor-infiltrating lymphocytes (TILs) and autologous tumor cells. Methods: Over 250 tissue and blood samples from untreated sarcoma patients have been collected. The tissue samples are dissected and used for in vitro expansion of TILs or tumor cells. TIL cultures are characterized via flow cytometry and TIL responses are quantified using an IFNy ELISA. Tumor cultures are validated with RT-qPCR and dd-PCR to ensure tumor-specific mutations are retained. After characterizing and validating the cultures, autologous tumor cells and TILs are co-cultured to examine tumor-immune interactions. Outcomes of immune activity in the presence of tumor cells and tumorigenicity are evaluated to better understand the mechanisms that may be implicated in sarcoma immunotherapy. Results: At the end of a 3-week expansion period, of the 93 primary tumor samples cultured for TILs, only 7 did not yield any TIL growth; however, the final TIL yield varied between different patient samples, ranging from 0.005 - 83M cells. Both TIL cultures expanded from different samples of the same tumor and from tumors of different patients demonstrated variable cell proportions of CD4+ and CD8+ TILs. Some cultures also contained a proportion of CD56+ cells. ELISA documented TIL responses to stimulation in all collected cultures, indicating a viable and functional population. Of the 24 primary tumor samples cultured, 17 (8 of 10 undifferentiated pleomorphic sarcomas; 7 of 10 myxofibrosarcomas; 2 of 4 osteosarcomas) generated viable tumor cell cultures as defined by the presentation of stable growth beyond passage 5. Conclusion: Tumor cells and functional TILs can be isolated and expanded from most sarcomas; however, the methods must be optimized for each case. Further tumor culture validation by whole exome sequencing in combination with ddPCR is ongoing. A benchmark of an effective and clinically significant TIL yield will need to be better defined going forward. TILs are active in vitro and vary in population composition. Future experiments will focus on evaluating the killing capacity and tumor specificity of TILs. Citation Format: Alice Ko, Victoria Coward, Minji Lee, Kayley Xu, Nalan Gokgoz, Brendan Dickson, Jay Wunder, Irene L. Andrulis. Investigating tumor-immune interactions in adult sarcomas of the extremities [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3875.
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