Serena Pellegatta

Tumor-infiltrating lymphocyte (TIL)-therapy has received FDA approval for the treatment of advanced melanoma and shows potential for broader applications in solid tumors, including glioblastoma. In this study, tumor-reactive TILs (tr-TILs) are isolated and enriched for CD137 expression from cavitron ultrasonic aspirator (CUSA) emulsions of 161 adult patients diagnosed with diffuse gliomas. Tr-TILs are successfully expanded in 87 out of the 161 patients, reflecting an expansion rate of 54%. Notably, the presence of IDH1 mutation and the cumulative dose of steroids are identified as significant negative predictors of expansion efficacy. The expanded tr-TILs exhibit distinct phenotypic and molecular dysfunctional features yet show upregulated expression of progenitor/memory-like markers and polyclonal T-cell receptors. Importantly, these tr-TILs demonstrate specific antitumor reactivity against autologous tumor cells in both in vitro and in vivo xenograft models. These findings provide a compelling background for a personalized immunotherapeutic approach while tackling one of the most significant challenges in oncology.

Immunosuppressive myeloid cells, such as microglia and macrophages, play a key role in mediating resistance to immunotherapy in glioblastoma patients. Bulk RNA sequencing analysis revealed elevated expression of Klotho ( Kl ) in gliomas derived from irradiated glioma‐bearing mice. Klotho , which encodes an anti‐aging protein, was found to be upregulated in glioma‐associated microglia/macrophages (GAMs) exhibiting an M1 pro‐inflammatory phenotype. This upregulation appeared to enhance the antitumor efficacy of a combination of radiotherapy and dendritic cell (DC) immunotherapy. Furthermore, transcript levels of KL in tumor specimens and corresponding serum levels in glioblastoma patients undergoing DC immunotherapy were correlated with favorable prognostic outcomes and improved treatment responses. Given its expression in human M1‐like GAMs, serum KL levels can offer valuable insights into the immune microenvironment and hold clinical significance as a peripheral biomarker. These findings highlight the pivotal role of Klotho as a prognostic biomarker for predicting responses to immunotherapy, with potential applications for monitoring tumor progression or regression through changes in serum levels.

Tumor-infiltrating lymphocyte (TIL)-therapy has received FDA approval for the treatment of advanced melanoma and shows potential for broader applications in solid tumors, including glioblastoma. In this study, tumor-reactive TILs (tr-TILs) were isolated and enriched for CD137 expression from cavitron ultrasonic aspirator (CUSA) emulsions of 161 adult patients diagnosed with diffuse gliomas. tr-TILs were successfully expanded in 87 out of the 161 patients, reflecting an expansion rate of 54%. Notably, the presence of IDH1 mutation and the cumulative dose of steroids were identified as significant negative predictors of expansion efficacy. The expanded tr-TILs exhibited distinct phenotypic and molecular dysfunctional features yet showed upregulated expression of progenitor/memory-like markers and polyclonal T-cell receptors. Importantly, these tr-TILs demonstrated specific antitumor reactivity against autologous tumor cells in both in vitro and in vivo xenograft models. These findings provide a compelling background for a personalized immunotherapeutic approach while tackling one of the most significant challenges in oncology.

Fluorescein-mediated sonodynamic therapy (FL-SDT) is an extremely promising approach for glioma treatment, resulting from the combination of low-intensity focused ultrasound (FUS) with a sonosensitizer. In the present study, we evaluated the efficacy and immunomodulation of SDT with fluorescein as the sonosensitizer in immunocompetent GL261 glioma mice for the first time. In vitro studies demonstrated that the exposure of GL261 cells to FL-SDT induced immunogenic cell death and relevant upregulation of MHC class I, CD80 and CD86 expression. In vivo studies were then performed to treat GL261 glioma-bearing mice with FL-SDT, fluorescein alone, or FUS alone. Perturbation of the glioma-associated macrophage subset within the immune microenvironment was induced by all the treatments. Notably, a relevant depletion of myeloid-derived suppressor cells (MDSCs) and concomitant robust infiltration of CD8+ T cells were observed in the SDT-FL-treated mice, resulting in a significant radiological delay in glioma progression and a consequent improvement in survival. Tumor control and improved survival were also observed in mice treated with FL alone (median survival 41.5 days, p > 0.0001 compared to untreated mice), reflecting considerable modulation of the immune microenvironment. Interestingly, a high circulating lymphocyte-to-monocyte ratio and a very low proportion of MDSCs were predictive of better survival in FL- and FL-SDT-treated mice than in untreated and FUS-treated mice, in which elevated monocyte and MDSC frequencies correlated with worse survival. The immunostimulatory potential of FL-SDT treatment and the profound modulation of most immunosuppressive components within the microenvironment encouraged the exploration of the combination of FL-SDT with immunotherapeutic strategies.

Supplementary Figures and Legends

Supplementary Figures and Legends

Chimeric antigen receptor (CAR) tonic signaling, defined as spontaneous activation and release of proinflammatory cytokines by CAR-T cells, is considered a negative attribute because it leads to impaired antitumor effects. Here, we report that CAR tonic signaling is caused by the intrinsic instability of the mAb single-chain variable fragment (scFv) to promote self-aggregation and signaling via the CD3ζ chain incorporated into the CAR construct. This phenomenon was detected in a CAR encoding either CD28 or 4-1BB costimulatory endodomains. Instability of the scFv was caused by specific amino acids within the framework regions (FWR) that can be identified by computational modeling. Substitutions of the amino acids causing instability, or humanization of the FWRs, corrected tonic signaling of the CAR, without modifying antigen specificity, and enhanced the antitumor effects of CAR-T cells. Overall, we demonstrated that tonic signaling of CAR-T cells is determined by the molecular instability of the scFv and that computational analyses of the scFv can be implemented to correct the scFv instability in CAR-T cells with either CD28 or 4-1BB costimulation.

Chimeric antigen receptor (CAR) tonic signaling, defined as spontaneous activation and release of proinflammatory cytokines by CAR-T cells, is considered a negative attribute because it leads to impaired antitumor effects. Here, we report that CAR tonic signaling is caused by the intrinsic instability of the mAb single-chain variable fragment (scFv) to promote self-aggregation and signaling via the CD3ζ chain incorporated into the CAR construct. This phenomenon was detected in a CAR encoding either CD28 or 4-1BB costimulatory endodomains. Instability of the scFv was caused by specific amino acids within the framework regions (FWR) that can be identified by computational modeling. Substitutions of the amino acids causing instability, or humanization of the FWRs, corrected tonic signaling of the CAR, without modifying antigen specificity, and enhanced the antitumor effects of CAR-T cells. Overall, we demonstrated that tonic signaling of CAR-T cells is determined by the molecular instability of the scFv and that computational analyses of the scFv can be implemented to correct the scFv instability in CAR-T cells with either CD28 or 4-1BB costimulation.

The interpretation of the presence and function of immune infiltration in glioblastoma (GBM) is still debated. Over the years, GBM has been considered a cold tumor that is less infiltrated by effector cells and characterized by a high proportion of immunosuppressive innate immune cells, including GBM-associated microglia/macrophages (GAMs). In this context, the failure of checkpoint inhibitors, particularly in recurrent GBM (rGBM), caused us to look beyond the clinical results and consider the point of view of immune cells. The tumor microenvironment in rGBM can be particularly hostile, even when exposed to standard immunomodulatory therapies, and tumor-infiltrating lymphocytes (TILs), when present, are either dysfunctional or terminally exhausted. However, after checkpoint blockade therapy, it was possible to observe specific recruitment of adaptive immune cells and an efficient systemic immune response. In this review article, we attempt to address current knowledge regarding the tumor and immune microenvironment in rGBM. Furthermore, immunosuppression induced by GAMs and TIL dysfunction was revisited to account for genetic defects that can determine resistance to therapies and manipulate the immune microenvironment upon recurrence. Accordingly, we reevaluated the microenvironment of some of our rGBM patients treated with dendritic cell immunotherapy, with the goal of identifying predictive immune indicators of better treatment response.