Browsing by Author "Unutmaz, Derya"

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    Mechanisms of T-Cell Exhaustion in Pancreatic Cancer
    (MDPI, 2020-01-01) Saka, Didem; Gokalp, Muazzez; Piyade, Betul; Cevik, Nedim Can; Sever, Elif Arik; Unutmaz, Derya; Ceyhan, Guralp O.; Demir, Ihsan Ekin; Asimgil, Hande
    T-cell exhaustion is a phenomenon that represents the dysfunctional state of T cells in chronic infections and cancer and is closely associated with poor prognosis in many cancers. The endogenous T-cell immunity and genetically edited cell therapies (CAR-T) failed to prevent tumor immune evasion. The effector T-cell activity is perturbed by an imbalance between inhibitory and stimulatory signals causing a reprogramming in metabolism and the high levels of multiple inhibitory receptors like programmed cell death protein-1 (PD-1), cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), T cell immunoglobulin and mucin domain-containing protein 3 (TIM-3), and Lymphocyte-activation gene 3 (Lag-3). Despite the efforts to neutralize inhibitory receptors by a single agent or combinatorial immune checkpoint inhibitors to boost effector function, PDAC remains unresponsive to these therapies, suggesting that multiple molecular mechanisms play a role in stimulating the exhaustion state of tumor-infiltrating T cells. Recent studies utilizing transcriptomics, mass cytometry, and epigenomics revealed a critical role of Thymocyte selection-associated high mobility group box protein (TOX) genes and TOX-associated pathways, driving T-cell exhaustion in chronic infection and cancer. Here, we will review recently defined molecular, genetic, and cellular factors that drive T-cell exhaustion in PDAC. We will also discuss the effects of available immune checkpoint inhibitors and the latest clinical trials targeting various molecular factors mediating T-cell exhaustion in PDAC.
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    Targeting SARS-CoV-2 infection through CAR-T-like bispecific T cell engagers incorporating ACE2
    (WILEY, 2022-01-01) Dogan, Mikail; Kozhaya, Lina; Placek, Lindsey; Karabacak, Fatih; Yigit, Mesut; Unutmaz, Derya
    Objectives. Despite advances in antibody treatments and vaccines, COVID-19 caused by SARS-CoV-2 infection remains a major health problem resulting in excessive morbidity and mortality and the emergence of new variants has reduced the effectiveness of current vaccines. Methods. Here, as a proof-of-concept, we engineered primary CD8 T cells to express SARS-CoV-2 Spike protein-specific CARs, using the extracellular region of ACE2 and demonstrated their highly specific and potent cytotoxicity towards Spike-expressing target cells. To improve on this concept as a potential therapeutic, we developed a bispecific T cell engager combining ACE2 with an anti-CD3 scFv (ACE2-Bite) to target infected cells and the virus. Results. As in CAR-T cell approach, ACE2-Bite endowed cytotoxic cells to selectively kill Spike-expressing targets. Furthermore, ACE2-Bite neutralized the pseudoviruses of SARS-CoV, SARS-CoV-2 wild-type, and variants including Delta and Omicron, as a decoy protein. Remarkably, ACE2-Bite molecule showed a higher binding and neutralization affinity to Delta and Omicron variants compared to SARS-CoV-2 wild-type Spike proteins. Conclusion. In conclusion, these results suggest the potential of this approach as a variant-proof, therapeutic strategy for future SARS-CoV-2 variants, employing both humoral and cellular arms of the adaptive immune response.