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Previous Volume 359:539-541 July 31, 2008 Number 5 Next

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To the Editor: Glioblastoma is a malignant brain tumor with overall survival rates of less than 3.3% at 5 years.¹ Few effective treatments are available. The durability of a radiographically defined response to treatment is limited, and median survival is less than 2 years.

We are conducting a phase 1 trial of autologous dendritic-cell vaccination as adjunctive therapy in glioma, a study that has been approved by the institutional review board at the University of California, Los Angeles. All patients are treated with surgery, standard radiotherapy, and temozolomide, followed by vaccination with dendritic cells that are pulsed with an autologous tumor lysate. To date, we have enrolled 14 patients with newly diagnosed glioblastoma (World Health Organization grade IV).

Here we describe Patient 4-908 with glioblastoma who was enrolled in the trial and in whom a robust CD8+ T-cell response to the pp65 immunodominant epitope of human cytomegalovirus (CMV) began immediately after one injection of the vaccine (Figure 1A and 1B). We found that after vaccination, 4.4% of the patient's CD8+ T cells were specific for pp65. The vaccination was not associated with any systemic symptoms. Local lymphadenopathy was observed at the time of the expansion of the human CMV–specific T cells.²

View larger version (25K): [in this window] [in a new window]   Figure 1. Induction of Immune Responses Specific for Human Cytomegalovirus (CMV) after Vaccination with Dendritic Cells Pulsed with Autologous Tumor Lysate. In Panel A, histograms show human CMV–specific CD8+ T cells (CD4–, CD13–, and CD19–, CD3+CD8+ CMV pp65+) before treatment, after the first and second dendritic-cell vaccinations, and at 6 months after vaccination. The percentages shown are those of all CD3+CD8+ T cells. In Panel B, combined tetramer and intracellular cytokine staining of peripheral-blood mononuclear cells (PBMCs) from Patient 4-908 is shown before treatment and after two vaccinations with dendritic cells. PBMCs were restimulated for 6 hours, with and without the immunodominant human CMV peptide, in the presence of Brefeldin A, followed by surface-antibody labeling, fixation and permeabilization, and labeling of intracellular interferon-. In a clockwise fashion, the percentages in each gate reflect the frequency of CD3+CD8+ T cells that were positive for CMV pp65 and negative for interferon-, positive for both CMV and interferon-, and negative for CMV but positive for interferon- . In Panel C, serum cytokine levels are shown during the initial dendritic-cell vaccination regimen once every 2 weeks, in which 50 µl of serum was tested for the presence of cytokines related to type 1 helper T cells (interleukin-2, tumor necrosis factor [TNF-], and interferon-) and type 2 helper T cells (interleukin-4, -6, and -10) by cytometric bead array at the indicated times.

 
The patient's tumor appeared to be infected with CMV. Immunohistochemical staining of tumor tissue showed focal expression of human CMV pp65 in the tumor but not in a tumor from Patient 2-261 with an HLA-A0201–positive glioblastoma, in whom a CMV-specific immune response did not occur after vaccination. In Patient 4-908, serum cytokine measurements revealed increased levels of tumor necrosis factor after one dendritic-cell vaccination, a response that peaked 2 weeks after the second vaccination (Figure 1C).

An association has been discovered between human CMV and malignant gliomas.^3,4,5 We found that a CMV-specific CD8+ T-cell response was induced in a patient with glioblastoma after therapeutic vaccination with dendritic cells pulsed with an autologous tumor lysate. Our results suggest that the presence of human CMV in glial cells could serve as an immunotherapeutic target in glioblastoma. The relative ease of eliciting an immune response against viral antigens contrasts with the difficulty of immunization against "self" tumor antigens. This case highlights the potential for targeted vaccination strategies with the use of dendritic cells as an adjunct to standard treatments for glioblastoma, although multicenter, randomized studies will be necessary to demonstrate clinical efficacy.

Robert M. Prins, Ph.D.
Timothy F. Cloughesy, M.D.
Linda M. Liau, M.D., Ph.D.
University of California, Los Angeles
Los Angeles, CA 90095
rprins{at}mednet.ucla.edu

Drs. Prins and Liau report receiving research support from Northwest Biotherapeutics. No other potential conflict of interest relevant to this letter was reported.

References

1. Deorah S, Lynch CF, Sibenaller ZA, Ryken TC. Trends in brain cancer incidence and survival in the United States: Surveillance, Epidemiology, and End Results Program, 1973 to 2001. Neurosurg Focus 2006;20:E1-E1. [Medline]
2. Liau LM, Prins RM, Kiertscher SM, et al. Dendritic cell vaccination in glioblastoma patients induces systemic and intracranial T-cell responses modulated by the local central nervous system tumor microenvironment. Clin Cancer Res 2005;11:5515-5525. [Free Full Text]
3. Cobbs CS, Harkins L, Samanta M, et al. Human cytomegalovirus infection and expression in human malignant glioma. Cancer Res 2002;62:3347-3350. [Free Full Text]
4. Ho KL, Gottlieb C, Zarbo RJ. Cytomegalovirus infection of cerebral astrocytoma in an AIDS patient. Clin Neuropathol 1991;10:127-133. [ISI][Medline]
5. Mitchell DA, Xie W, Schmittling R, et al. Sensitive detection of human cytomegalovirus in tumors and peripheral blood of patients diagnosed with glioblastoma. Neuro Oncol 2008;10:10-18. [Free Full Text]

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This article has been cited by other articles:

• Meyer, M. A., Wen, P. Y., Kesari, S. (2008). Malignant Gliomas in Adults. NEJM 359: 1850-1850 [Full Text]