3 results on '"Vardeu A"'
Search Results
2. 624 IFNγ secreted by tebentafusp (IMCgp100)-redirected T cells inhibits expression of melanin synthesis pathway genes in healthy melanocytes
- Author
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Jane Houghton, Laura Collins, Koustubh Ranade, Adel Benlahrech, Gabrielle S. Le Provost, Camille Britton-Rivet, Jane Harper, David Depoil, and Mariantonella Vardeu
- Subjects
Granzyme B production ,business.industry ,Melanoma ,medicine.medical_treatment ,T cell ,Vitiligo ,Melanocyte ,medicine.disease ,Melanin ,medicine.anatomical_structure ,Cytokine ,Antigen ,Cancer research ,medicine ,business - Abstract
Background Tebentafusp (IMCgp100) is a bispecific T cell redirector comprised of an affinity-enhanced TCR recognising melanocyte lineage antigen gp100 and a T cell engaging anti-CD3 scFv domain. Tebentafusp has shown activity as monotherapy in advanced cutaneous and uveal melanoma (Middleton et al., ASCO 2019), and we have previously reported that over half of uveal melanoma patients treated with tebentafusp display melanocyte-related adverse events (MRAE). These include vitiligo/skin hypopigmentation, leukotrichia, and hyperpigmentation and, collectively, are associated with better overall survival in uveal patients receiving tebentafusp (Orloff et al, AACR 2020). In this study, we dissected the mechanisms by which tebentafusp may induce MRAE and highlight the potential clinical significance. Methods In vitro studies were conducted to assess the direct and indirect effects of tebentafusp on epidermal melanocytes from healthy donors. Expression of gp100 and the gp100:HLA*02:01 target complex by melanocytes were quantified at the mRNA level and on the cell surface by confocal microscopy, respectively. Melanocytes co-cultured with PBMC and increasing concentrations of tebentafusp were assessed for their susceptibility to lysis and/or ability to stimulate cytokine production. These readouts were compared to gp100-positive and negative melanoma cancer cell lines. Melanin production by melanocytes was quantified and the melanin synthesis pathway interrogated at the mRNA and protein level following exposure to secretomes from tebentafusp-redirected PBMC against melanoma cancer cells. Results Healthy melanocytes expressed 2 to 3-fold lower levels of gp100 peptide-HLA complexes on their surface compared to gp100-positive melanoma cell lines. In the presence of tebentafusp, this lower target expression translated into 3–6 fold lower levels of IFNγ and more than 100 fold lower granzyme B production by redirected T cells and these melanocytes were resistant to direct tebentafusp-induced killing (EC50 for melanocytes greater than 1nM vs EC50 melanoma cell lines of 23–50 pM). Supernatants from T cells activated in response to melanoma cancer cells by tebentafusp downregulated the melanin content of healthy melanocytes (20–30% reduction). Western blotting revealed 30–40% inhibition of two key components of the melanin synthesis pathway; the tyrosinase-related protein (TRP)-1 and TRP-2. This inhibition was reversed by blocking IFNγ in supernatants from activated T cells. Conclusions MRAEs, especially vitiligo, associated with response to tebentafusp, may be explained, at least in part, by the downregulation of melanin biosynthesis pathway genes by IFNγ secreted by tebentafusp-activated T cells. Ethics Approval The study was approved by the South Central - Oxford A Research Ethics Committee (UK), REC reference 13/SC/0226 References Middleton, et al., Relationship between clinical efficacy and AEs of IMCgp100, a novel bispecific TCR–anti-CD3, in patients with advanced melanoma. Journal of Clinical Oncology. 2019. Orloff, et al., Vitiligo and other clinical melanocyte-related adverse events following tebentafusp (IMCgp100) exposure in patients with uveal melanoma. AACR (American Association for Cancer Research), 2020.
- Published
- 2020
3. Intravenous administration of viral vectors expressing prostate cancer antigens enhances the magnitude and functionality of CD8+ T cell responses.
- Author
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Vardeu A, Davis C, McDonald I, Stahlberg G, Thapa B, Piotrowska K, Marshall MA, Evans T, Wheeler V, Sebastian S, and Anderson K
- Subjects
- Male, Humans, Mice, Animals, Mice, Inbred C57BL, CD8-Positive T-Lymphocytes, Vaccinia virus, Administration, Intravenous, Antigens, Neoplasm, Oxidoreductases, Prostate-Specific Antigen, Prostatic Neoplasms genetics, Prostatic Neoplasms therapy
- Abstract
Background: The use of immunotherapeutic vaccination in prostate cancer is a promising approach that likely requires the induction of functional, cytotoxic T cells . The experimental approach described here uses a well-studied adenovirus-poxvirus heterologous prime-boost regimen, in which the vectors encode a combination of prostate cancer antigens, with the booster dose delivered by either the intravenous or intramuscular (IM) route. This prime-boost regimen was investigated for antigen-specific CD8+ T cell induction., Methods: The coding sequences for four antigens expressed in prostate cancer, 5T4, PSA, PAP, and STEAP1, were inserted into replication-incompetent chimpanzee adenovirus Oxford 1 (ChAdOx1) and into replication-deficient modified vaccinia Ankara (MVA). In four strains of mice, ChAdOx1 prime was delivered intramuscularly, with an MVA boost delivered by either IM or intravenous routes. Immune responses were measured in splenocytes using ELISpot, multiparameter flow cytometry, and a targeted in vivo killing assay., Results: The prime-boost regimen was highly immunogenic, with intravenous administration of the boost resulting in a sixfold increase in the magnitude of antigen-specific T cells induced and increased in vivo killing relative to the intramuscular boosting route. Prostate-specific antigen (PSA)-specific responses were dominant in all mouse strains studied (C57BL/6, BALBc, CD-1 and HLA-A2 transgenic)., Conclusion: This quadrivalent immunotherapeutic approach using four antigens expressed in prostate cancer induced high magnitude, functional CD8+ T cells in murine models. The data suggest that comparing the intravenous versus intramuscular boosting routes is worthy of investigation in humans., Competing Interests: Competing interests: All authors are employees of Vaccitech, a public company engaged in biomedical research., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)
- Published
- 2022
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