Work

Expansion of T Cells Targeting Multiple Antigens of CMV, EBV, and Adenovirus to Provide Broad Antiviral Specificity After Stem Cell Transplantation

Year: 2011

Type: article

Abstract: Hematopoietic Stem Cell Transplantation is the treatment of choice for many common malignancies. However, recipients are susceptible to viral infections after transplant. Antiviral drugs can be effective, but are toxic and can become drug-resistant. Another option is the administration of virus-specific donor-derived cytotoxic T lymphocytes (CTL). Using a chimeric adenovirus expressing the immunodominant CMV antigen pp65 (Ad5f35pp65) to modify antigen-presenting cells, we generated CTL specific for EBV, CMVpp65 and Adenovirus (Multivirus-specific CTL) from healthy donors. We have infused 26 patients with multivirus-specific CTL and have shown protection against all 3 viruses in vivo without significant toxicity. However, while all patients have been protected against EBV and Adenovirus, > 10% of patients developed CMV reactivation after CTL infusion, suggesting that targeting a single CMV antigen may not be entirely protective. After solid organ transplantation, IE-1-specific T cells were shown to be the most protective against CMV infection and after CMV vaccine, recipients have a stronger and more robust IE-1 response when compared to pp65. Therefore we sought to develop a GMP-compliant strategy to generate CTL targeting two CMV antigens (pp65 and IE-1) while not losing the breadth of specificity to EBV and adenovirus. CTL were generated by transducing monocytes (first stimulation) and then EBV-LCL with an Ad5f35-IE-1-I-pp65 vector at subsequent stimulations. Resultant T cells recognized CMV pp65 (mean:330; median:273; range:47-995) and IE-1 (mean:154; median:154; range:11-505), Adenovirus hexon (mean:189; median:153; range:30-465) and penton (mean:109; median:37 range:1-353), and EBV-LCL(mean:79; median: 55 range:9-301) as measured by IFN-γ ELISPOT and pentamer analysis. CTL were also able to lyse EBV, CMV, and adenovirus targets in cytotoxicity assays as well as HLA-matched CMV AD169-infected allogeneic fibroblasts. Importantly, the new multivirus-CTL recognize at least two antigens per virus, in addition to recognizing a breadth of epitopes within each antigen. In conclusion, we have developed a strategy to expand multivirus CTL targeting at least 2 antigens from EBV, CMV, and adenovirus thus increasing the breadth of the antiviral response and have begun the process of translating this to the clinic to improve immunity to CMV after transplantation.

Source: Transplantation and Cellular Therapy

DOI: 10.1016/j.bbmt.2010.12.182